Posts Tagged ‘pcb design’

Friday, December 13th, 2024

How to make two sided pcb Altium? Be familiar with the interface and basic operations of Altium Designer, accurately design the circuit schematic diagram, reasonably plan the PCB layout, make full use of the double-sided space, conduct fine wiring, ensure signal integrity, and correctly set the rules and parameters to meet production requirements.

What is a double-sided PCB?

Double-Sided PCB refers to a printed circuit board with conductive copper layers on both sides, and the circuit between the two sides is connected through through holes (small holes). This design enables double-sided PCBs to implement more complex circuit layouts in limited space without significantly increasing the board size.

Double-sided PCBs are widely used in various application scenarios that require complex circuit layouts and high-density assembly, such as computers, communication equipment, industrial control, and consumer electronics.

Because it can achieve more complex circuit designs in a limited space, double-sided PCB is particularly suitable for applications that require higher-function electronic equipment, such as smart home equipment, computer hardware, medical equipment, etc.

How to make two sided pcb in Altium?

Here are the general steps for making a double-sided PCB in Altium:

Create a project: In Altium Designer, select “File” > “New” > “Project” to create a new PCB project.

Draw a schematic: Select “File” > “New” > “Schematic” to create a new schematic file. Add the required components to the schematic and connect them using wires.

Add package library: If you need to use a custom package library, you need to add it to the project. Select Design > Add/Remove Library and select the desired footprint library.

Generate PCB: After the schematic is drawn, select “Design” > “Update PCB Document” to import the components and connection information in the schematic into the PCB.

Layout components: In PCB, components are laid out according to design requirements. You can use Altium’s automatic layout tools or manual layout.

Routing: Use Altium’s routing tools to route the connections between components. You can choose automatic routing or manual routing.

Add silkscreens and logos: Add silkscreens and logos to the PCB to easily identify components and connections.

Check and Validate: Use Altium’s Design Rule Checker tool to check that your PCB design meets requirements. Electrical rule checks, wiring rule checks, etc. can be performed.

Generate manufacturing files: After the PCB design is completed, select “File” > “Fabrication Outputs” to generate manufacturing files, such as Gerber files, drilling files, etc.

How to make two-sided PCB?

After designing the layout of the double-sided PCB in the PCB design software according to the circuit schematic diagram, the production process begins.

The complete process of making double-sided PCB:

Preparation materials: Choose a copper-clad laminate covered with copper foil of a specific thickness (such as 18μm, 35μm, etc.) on both sides, and determine the copper foil specifications according to circuit requirements.

Drilling: According to the drilling documents, use a CNC drilling machine to drill high-precision holes to ensure the connection paths for the circuits on each layer.

Copper immersion: Place the drilled PCB board in a copper immersion liquid to deposit a thin copper layer on the hole wall, laying the foundation for subsequent copper electroplating and ensuring the reliability of electrical connections.

Copper electroplating: Use the PCB board as the cathode to energize the copper ion plating solution, thicken the copper layer to the design standard, and enhance the electrical conductivity and mechanical properties.

Exposure and development: The Gerber file is made into a film. After applying photoresist to the copper-clad board, the film pattern is printed on the board through exposure equipment, and then the unexposed photoresist is dissolved with a developer to initially present the circuit pattern.

Etching: Use ferric chloride or acidic etching solution to dissolve the copper foil that is not protected by the photoresist, and form precise lines on both sides of the copper-clad board. Then use a film stripping solution to remove the remaining photoresist.

Make the solder mask layer: Use screen printing to apply solder mask ink of the selected color on the circuits on both sides of the board, and use screen printing to print white character ink on the corresponding positions of the cured solder mask layer to mark component information to facilitate assembly and debugging.

Drying treatment: Drying fixes the character ink to avoid fading and blurring.

Surface treatment: Dip tin or spray to coat the pad with tin layer to improve solderability, suitable for products with regular soldering requirements.

Can you put components on both sides of a PCB?

Components can be placed on both sides of the PCB. Both sides of the PCB double-sided panel can be wired and components placed, which can reduce the difficulty of wiring and is suitable for the design of complex circuits.

In a double-board design, larger and denser components such as QFP and BGA are usually placed on the top layer of the board, while plug-in components can only be placed on the top layer. Smaller components and components are placed on the other side (bottom layer) of the plug-in components. Chip components with a small number of pins and loose arrangement.

How do you flip a PCB in Altium?

Use the shortcut key: Press the “V” key and then the “B” key to quickly flip the PCB view to the bottom layer. This method is like turning the PCB board over visually, making it easier to view the underlying component layout, wiring, etc.

Operation through the menu: Select the “View” menu, find the “Flip Board” option in the drop-down menu, and click it to flip the PCB view between the top and bottom layers. This method is relatively intuitive and suitable for users who are not familiar with shortcut keys.

How do you flip a component to the bottom in Altium?

Menu operation: Hold down the “Ctrl” key and use the left mouse button to click the components that need to be flipped one by one to select them all. Then follow the menu operation steps for flipping a single component, that is, select “Edit” – “Move” – ”Flip Selection”, so that multiple selected components can be flipped to the bottom together.

Shortcut key operation: First select multiple components, the selection method is the same as above, also hold down the “Ctrl” key and click the components. Then press the “L” key to flip these selected components to the bottom layer at the same time.

How do I mirror graphics in Altium?

In the schematic editing environment, select the component that needs to be mirrored. You can select it by left-clicking the component with the mouse. Then select the “Edit” menu and click on the “Mirror” option. Or use the shortcut key “Ctrl + M” to mirror the component in the horizontal direction. Properties such as the pin connections of the component will not change, only the graphic appearance will be mirrored.

In the PCB editing environment, select the component to be mirrored by clicking it directly with the left mouse button. Select the “Move” submenu under the “Edit” menu and click on the “Mirror Selection” option. The component will be mirrored with the axis perpendicular to the PCB board plane as the axis of symmetry. This is useful when adjusting component layout, especially when you need to flip the component from top to bottom and mirror it at the same time, etc.

In addition, for some regularly shaped components (such as rectangular components), you can also select the component and hold down the “L” key to achieve the effect of flipping and mirroring the component between layers.

How do I rotate a whole PCB in Altium?

Use keyboard shortcuts to rotate in the PCB Editor:

Select the entire PCB (you can select the entire PCB through the “Edit” menu – “Select” – “All”). Press “Space” to rotate the PCB counterclockwise in 90° increments. This is a faster way to rotate, making it easier to adjust the direction of the PCB during the layout and routing process to better fit the workspace or meet specific layout ideas.

Rotate via menu options:

Also select the entire PCB first. Select the “Edit” menu – “Move” – ”Rotate Selection”. In the pop-up dialog box, you can set the rotation angle. The PCB can be rotated accurately according to the design requirements, such as inputting any angle such as 45°, 60°, etc., and then clicking the “OK” button to complete the rotation operation. This method is relatively more flexible and can meet the rotation needs of non-integer multiples of 90°.

During the design process, pay attention to key points, be familiar with the operation of the software, accurately design the circuit schematic, reasonably plan the PCB layout, conduct fine wiring, set correct rules and parameters, and conduct strict inspection and optimization. Only in this way can the quality and reliability of PCB design be ensured and meet the needs of practical applications.

How to create a new PCB in Altium?

Creating a new PCB in Altium mainly includes the following steps:

1. Create a new PCB file

To create a new file: Open the Altium software, select the “File” menu, and then click the “New” option. In the pop-up submenu, select “PCB”, so that a new blank PCB file is created. You can also use the shortcut key “Ctrl + N”, and then select “PCB Document” in the pop-up “New Document” dialog box to create it.

2. Set PCB parameters

Unit setting: Select “Document Option” in the “Design” menu. In the pop-up dialog box, you can select the unit of the PCB. Generally, there are two units to choose from: imperial (mil) and metric (mm).

Grid setting: Also in the “Document Options” dialog box, switch to the “Grids” tab. You can set the Visible Grid and Snap Grid. The visible grid is used as a visual reference during the design process to help users align components and wiring.

Define the board frame: You can use the “Line” tool or the “Keep – Out” tool in the “Place” menu to draw the border of the PCB. If you use the “Line” tool, you need to manually draw a closed polygon to represent the shape of the PCB; the area drawn with the “Keep – Out” tool indicates the range where wiring is prohibited, and can also be used as the boundary of the PCB.

Precisely set the size: Select “Board Shape” in the “Design” menu, and then select “Redefine Board Shape”. At this time, the mouse cursor will become a cross shape. Use the mouse to click on the previously drawn board frame lines, and the software will automatically redefine the shape and size of the PCB based on these lines.

3. Add component library

Open the component library panel: In the “Libraries” panel on the right, if it is not displayed, you can open it through the “Workspace Panels” option in the “View” menu, and then select “Libraries”.

Add library files: In the component library panel, click the “Libraries” button, and in the pop-up “Available Libraries” dialog box, select the “Install” option. Then find the required component library file in the file browser (usually *.IntLib or *.SchLib and *.PcbLib files), select and click “Open” to add the component library to the software.

4. Place components

Find components: After the component library is added, you can find the components that need to be placed on the PCB in the component library panel. You can quickly locate the component by entering the component name, model or package type in the search box.

Place components: After finding the required component, double-click the component name or click the component name and select the “Place” option. The mouse cursor will change to the shape of the component. Move the mouse to the appropriate position in the PCB editing area and click the left mouse button to place the component. During the placement process, you can rotate the component by pressing the space bar to adjust the direction of the component.

5. Component layout

Manual layout: After placing the component, you need to layout the component. When manually laying out, you can adjust the position of the component based on factors such as the electrical connection relationship between components, signal flow, and the mechanical structure of the PCB.

Automatic layout (optional): Altium also provides an automatic layout function. Select the “Component Placement” option in the “Tools” menu, and then select “Auto Place”. However, the result of automatic layout may not be ideal, and manual adjustments are usually required based on the automatic layout to achieve the best layout effect.

6. Wiring

Set wiring rules: Before wiring, you need to set wiring rules. Select the “Rules” option in the “Design” menu. In the pop-up “PCB Rules and Constraints Editor” dialog box, you can set various routing rules such as line width, routing spacing, and via size.

Start routing: Select the “Interactive Routing” option in the “Route” menu, or use the shortcut key “Ctrl + W”, and the mouse cursor will become a cross shape. Click a component pin as the starting point for routing, and then move the mouse to the target pin. The software will automatically generate routing according to the set routing rules. During the routing process, you can switch the routing mode by pressing the “Shift + Space” key combination, such as 45° routing, 90° routing, etc.

7. Design Verification

Electrical Rule Check (ERC): Select the “Design Rule Check” option in the “Tools” menu. In the pop-up “Design Rule Check” dialog box, set the items and parameters to be checked, and then click the “Run DRC” button. The software will check whether the PCB design complies with the previously set routing rules, such as whether there are short circuits, open circuits, insufficient spacing, etc., and generate a check report.

3D view check (optional): Altium also provides a 3D view function, which can help users check the PCB design more intuitively. Select the “Switch to 3D” option in the “View” menu, and the software will display the PCB design in 3D.

Through the above steps, you can create a new PCB in Altium. In the actual design process, you may need to repeatedly adjust and optimize each step according to the specific design requirements and complexity to obtain a high-quality PCB design.

What is the difference between a schematic and a PCB?

The main differences between a schematic and a PCB are in terms of definition, purpose, content, and form of expression.

1. Definition and purpose

Schematic: A schematic is also called a circuit diagram or electrical schematic. It uses graphic symbols to represent circuit components and their connections. The schematic mainly describes the working principle of an electronic device and does not involve a specific physical layout.

PCB: A PCB diagram is a printed circuit board diagram, which is a mapping drawing of a circuit board, detailing the routing, component location, size, and connection method of the circuit board. PCB diagram is the direct basis for the actual production of circuit boards. It is mainly used to guide the manufacturing and assembly process of PCB boards to ensure that components are placed correctly and lines are connected accurately.

2. Content and form of expression

Schematic diagram: The schematic diagram represents components and connection lines in a symbolic form, clearly showing the working principle and logical relationship of the circuit. It does not involve specific physical layout and size, so it is relatively flexible and easy to modify and optimize.

PCB diagram: The PCB diagram shows the actual layout and electrical connection of components, including copper foil lines, pads and vias. PCB diagram is the basis of circuit board manufacturing, involving specific physical layout and connection methods. Once determined, the modification is more complicated.

How to make a PCB from schematic?

Making a PCB from a schematic can be divided into the following steps:

Drawing a schematic diagram: Use circuit design software (such as Altium Designer, Eagle, etc.) to draw a circuit schematic diagram, including the connection relationship of each electronic component.

Design PCB: According to the component layout and connection relationship in the schematic diagram, PCB layout design is performed in the PCB design software, including component placement, wiring, etc.

Generate Gerber files: Export the designed PCB files as Gerber files, which is a standard PCB manufacturing file format that contains information about each layer of the PCB, such as copper foil layer, silk screen layer, solder mask layer, etc.

Make PCB: Send the generated Gerber files to the PCB manufacturer or use PCB manufacturing equipment for production. The PCB manufacturer will make the actual PCB circuit board according to the Gerber file.

Solder components: Solder the electronic components to the manufactured PCB circuit board to complete the circuit assembly.

Test and debug: Test and debug the assembled circuit board to ensure that the circuit functions normally.

Can Altium open Gerber files?

Altium Designer can open Gerber files. The specific steps are as follows:

Open Altium Designer software, select “File” in the menu bar, then select “New”, and then click “Cam document” in its drop-down submenu to create a new CAM file.

In the newly created CAM file, select the “Import” sub-item of the “File” menu item, and then select “Gerber” to start importing Gerber files.

Select the Gerber file to be opened in the pop-up window, click “Open”, and then click the “OK” button in the pop-up “Import Gerber” window, and the Gerber file can be successfully opened.

How do I convert PCB to schematic in Altium?

To convert PCB to schematic in Altium, first open the PCB file and export the network table through the “Design” menu (select the appropriate format such as Protel format). Then create a new schematic file and import the previously exported network table through the “Design” menu. Then manually adjust the component layout to make it more reasonable, and finally check whether the connection relationship is correct and improve the schematic, add annotations and logos, etc.

How do you place components from schematic in Altium?

In Altium Designer, first make sure that the required component library has been added. If not, you can add it by opening it in the “Workspace Panels” under the “Libraries” panel menu. Click the “Libraries” button, select “Install) in the “Available Libraries” dialog box that pops up, and find the component library file (such as *.SchLib) and add it.

In the “Libraries” panel, enter keywords such as component name, model or package type in the search box to find the components to be placed. You can also expand the corresponding library folder in the library list and browse to find the components.

After finding the component, there are two ways to place it. One is to double-click the component name directly, and the mouse cursor will change to the shape of the component; the other is to click the component name and select the “Place” option.

Move the mouse to the schematic editing area and click the left mouse button to place the component in the appropriate position. During the placement process, you can press the space bar to rotate the component and adjust its direction. Repeat this operation and place all the required components one by one into the schematic according to the schematic design.

How to make a PCB board step by step?

PCB manufacturing: After receiving the file, the PCB manufacturer manufactures it according to the file information. The manufacturing process includes multiple process steps such as inner layer pattern production, lamination, outer layer pattern production, drilling, electroplating, solder mask coating and silk screen characters.

Component assembly: After the PCB is manufactured, the components are assembled by manual welding or automated equipment, and the electronic components are installed on the PCB board according to the requirements of the BOM and schematic diagram to complete the production of the PCB board.

Functional test: Use test equipment to perform functional tests on the assembled PCB board to check whether the circuit can work normally and whether it meets the design requirements.

Performance debugging: For some complex circuits, performance debugging may be required, such as adjusting component parameters, optimizing signal processing, etc., to improve the performance and stability of the circuit.

In short, throughout the design process, continuous adjustments and optimizations are required to ensure the performance, reliability and manufacturability of the PCB. At the same time, Altium Designer also provides many other functions and tools to help you better complete PCB design tasks.

What Are PCB Designs Called?

PCB designs are often referred to by different names depending on the context or the stage of the design process. Let’s explore the most common terms:

1. PCB Layout

This is probably the most frequently used term. When someone mentions a PCB layout, they’re talking about the physical arrangement of components and the routing of electrical connections (also called traces) on the board.

Think of it like designing the floor plan of a house. The layout ensures that everything fits within the available space and that all the rooms (or in this case, components) are connected in the right way.

2. Circuit Board Design

Sometimes, you’ll hear people refer to the process as circuit board design. This term emphasizes the broader design aspect, from planning the circuit to placing components and routing connections. It’s a more general term that covers everything from the initial schematic to the final layout.

3. PCB Schematic

While the schematic is technically just one part of the design process, some people refer to the entire design as the schematic. This is more common among those who focus on the circuit’s logic rather than its physical structure.

4. Gerber Files

Once the design is complete, it’s converted into a set of files called Gerber files. These files contain all the information needed to manufacture the PCB. Sometimes, people use the term Gerber files to refer to the finished design, even though it’s technically just the output.

5. EDA (Electronic Design Automation) File

In professional environments, PCB designs are often called EDA files. These are the files created by design software like Altium Designer, KiCad, or Eagle. They contain all the details of the design, including the schematic, layout, and design rules.

What Is the Difference Between a PCB Design and a Schematic Design?

Many people use the terms PCB design and schematic design interchangeably, but they serve different purposes in the design process.

Schematic Design

Represents the electrical connections between components.
Focuses on the logic and functionality of the circuit.
Uses symbols to represent components like resistors, capacitors, and transistors.
Helps engineers understand how the circuit works.

PCB Design

Translates the schematic into a physical layout.
Focuses on the placement of components and routing of traces.
Considers factors like board size, layer count, and thermal performance.
Ensures the circuit can be manufactured and assembled.

In summary, the schematic shows what the circuit does, while the PCB design shows how it does it physically.

PCB Schematics Elements

A schematic is the starting point for any PCB design. It provides a clear visual representation of the circuit’s functionality. Here are the key elements of a schematic:

1. Component Symbols

Each component in the circuit is represented by a symbol. For example, a resistor is usually shown as a zigzag line, while a capacitor is two parallel lines.

2. Nets (Connections)

Lines connecting the symbols represent electrical connections, known as nets. These nets define how components interact with each other.

3. Reference Designators

Lines connecting the symbols represent electrical connections, known as nets. These nets define how components interact with each other.

4. Values and Ratings

The schematic also shows the values and ratings of components, such as the resistance of a resistor or the capacitance of a capacitor.

5. Power and Ground Symbols

Every circuit needs power and ground connections. These are represented by standard symbols, ensuring the circuit has a common reference point for voltage.

Common Terms in PCB Design

1. Silkscreen Layer

The silkscreen layer contains text, logos, and symbols printed on the surface of the PCB to help identify components and guide assembly. It can also include part numbers, component values, and polarity markings.

2. Via

A via is a hole in the PCB that allows electrical connections between different layers. Vias are often used in multi-layer PCBs to route signals between the top and bottom layers or inner layers.

3. Copper Pour

A copper pour is a large, solid region of copper that is poured over areas like ground or power planes. It helps reduce noise, increase current-carrying capacity, and improve thermal dissipation.

4. Trace Width

Trace width refers to the thickness of the copper traces used to connect components. The width of a trace must be designed to carry the required amount of current without overheating.

5. Drill Hole

A drill hole is a hole that is made in the PCB to accommodate components with leads or for vias. The size and placement of drill holes are critical to the assembly process.

6. Solder Mask

The solder mask is a protective layer applied over the PCB to prevent solder from bridging between pads. It also helps prevent oxidation of the copper traces and improves the board’s overall durability.

7. Pad

Pads are small copper areas on the PCB where components are mounted or soldered. Pads can be through-hole or surface-mount, depending on the type of component.

8. Bill of Materials (BOM)

The BOM is a comprehensive list of all the components required for the assembly of a PCB. It includes details like part numbers, quantities, and specifications for each component.

9. Impedance Control

Impedance control is the process of ensuring that the impedance of the PCB traces matches the requirements of the signals that will travel through them. This is important for high-speed and RF circuits.

10. Stack-up

Stack-up refers to the arrangement of layers in a multi-layer PCB. It defines how the copper, dielectric, and other materials are stacked to create the board.

11. Daisy-Chaining

Daisy-chaining is a method of connecting multiple components or pins in a series, often used in signal or power distribution systems within the PCB design.

12. Overcurrent Protection

Overcurrent protection refers to circuits designed to prevent excessive current from flowing through the PCB traces, often by using fuses or resistors that limit the current flow.

13. Design for Manufacturability (DFM)

DFM refers to designing the PCB in a way that makes it easier and more cost-effective to manufacture. This includes factors like trace width, pad size, and component placement.

14. Routing

Routing is the process of designing the electrical paths that connect the components on a PCB. Proper routing ensures that signals are carried efficiently with minimal interference.

15. Thermal Via

Thermal vias are specially designed vias used to transfer heat away from high-heat components to other parts of the PCB or a heat sink.

16. Electromagnetic Interference (EMI) Shielding

EMI shielding involves using design techniques, such as grounding and the use of shielding components, to protect sensitive parts of the PCB from electromagnetic interference.

17. Differential Pair

A differential pair is a set of two traces that carry complementary signals, often used in high-speed designs like USB or Ethernet to minimize noise and improve signal integrity.

18. Power Distribution Network (PDN)

The PDN refers to the system of traces and planes that deliver power to various components on the PCB. Proper PDN design is crucial to ensure reliable power delivery and minimize voltage drops.

19. Electrical Rule Check (ERC)

ERC is a process that checks the schematic design for electrical issues like unconnected nets, incorrect component connections, or incorrect power supply connections.

20. Multi-layer PCB

A multi-layer PCB contains more than two layers of conductive material and is used for more complex designs that require high-density circuits, especially in smaller devices.

21. Surface-Mount Technology (SMT)

SMT is a method for mounting components directly onto the surface of the PCB, rather than inserting them through holes. This allows for smaller, more compact designs.

22. Through-Hole Technology

Through-hole technology involves inserting component leads through holes in the PCB and soldering them on the opposite side. It’s commonly used for components that require strong mechanical bonds.

23. Hot Air Soldering

A method of soldering components onto the PCB using hot air, often used in reflow soldering processes for surface-mount components.

24. Trace Routing

Trace routing is the process of laying out the paths that the electrical signals will take through the PCB. Good trace routing ensures efficient and reliable signal transmission.

25. Tenting

Tenting refers to the process of covering the vias with a layer of solder mask, leaving the pad open. It helps prevent solder from flowing into vias during soldering.

PCB Design vs. PCB Layout

Although often used interchangeably, PCB design and PCB layout have different meanings:

PCB Design: Refers to the entire process, from schematic creation to generating manufacturing files.

PCB Layout: Specifically focuses on the physical arrangement of components and routing of traces on the board.

In simple terms, PCB layout is a part of the overall PCB design process.

PCB Design Process

Designing a PCB is a multi-step process that requires careful planning and attention to detail.

1. Schematic Capture

The process starts with creating a schematic diagram that defines the circuit’s functionality and connections.

2. Component Selection

Next, components are selected based on the circuit requirements. Factors like size, power rating, and cost are considered.

3. PCB Layout

Components are placed on the board, and traces are routed to connect them. This step requires balancing electrical performance with physical constraints.

4. Design Rules Check (DRC)

The layout is checked for errors or violations of design rules to ensure it meets manufacturing standards.

5. Gerber File Generation

Once the design is complete, Gerber files are generated. These files are used by manufacturers to produce the PCB.

6. Fabrication and Assembly

The PCB is fabricated, and components are assembled to create the final product.

FAQs

Q: What software is used for PCB design?

A: Popular software includes Altium Designer, Eagle, KiCad, and OrCAD.

Q: How many layers can a PCB have?

A: PCBs can have anywhere from one to 16 or more layers, depending on complexity.

Q: Why is trace width important?

A: Trace width affects the current-carrying capacity and signal integrity of the circuit.

Q: What is a multilayer PCB?

A: A multilayer PCB has multiple layers of copper separated by insulating material, allowing for more complex designs.

Q: How long does it take to design a PCB?

A: The time varies based on complexity. Simple designs may take a few days, while complex designs can take weeks.

What is PCB trace/line spacing?

PCB trace/line spacing refers to the minimum distance between two lines on the PCB board. This distance is usually used to avoid electrical interference and ensure the reliability of the circuit. The size of the line spacing will affect the crosstalk, electromagnetic compatibility and heat dissipation performance of the circuit.

PCB trace width and spacing Design Guide

The basic concept and importance of line spacing is that it directly affects the performance and reliability of the circuit. The size of the line spacing needs to ensure that the electrical coupling and interference between the circuits are minimized to ensure the normal operation of the circuit.

What are the rules for PCB trace spacing?

The basic rule for PCB trace spacing is that the distance from the center of the line to the center of the line should be greater than or equal to 3 times the line width (3W rule) to ensure that crosstalk between lines is reduced.

‌3W rule‌: In order to minimize the interference between lines, the distance from the center of the line to the center of the line should be greater than or equal to 3 times the line width (3W rule), which can reduce 70% of the electric field interference. If you need to achieve a higher interference reduction effect, you can use 10 times the line width (10W rule), which can reduce 95% of the interference.

‌Electrical safety spacing‌: According to the production capacity of the PCB manufacturer, the spacing between the wires and between the wires and the pads shall not be less than 4mil. Usually, the conventional spacing is set to about 10mil to ensure production quality and electrical safety.

‌Special signal lines‌: For signal lines that need to control impedance, such as RF signals, important single-ended signals, and differential signals, the line width and line spacing should be determined according to the stacking calculation to ensure stable signal transmission.

‌Other considerations‌: In PCB design, it is also necessary to pay attention to the signal lines to avoid using right angles and sharp angles. Using arcs or 135° obtuse angles can reduce reflections and standing waves.

What is the minimum line spacing in PCB?

The minimum line spacing in PCB is usually 4mil. ‌ This spacing is to avoid electrical interference and ensure the reliability of the circuit. The specific line spacing requirements depend on factors such as design specifications, application environment, and manufacturing process. ‌

In some high-precision applications, a smaller spacing may be required, but in general, the spacing should not be less than 4mil. The common spacing in conventional design is 10mil, which can ensure better production efficiency and circuit stability. ‌

What is the minimum line width for a PCB?

The minimum line width of a PCB is usually 6mil (about 0.153mm). This is because in high-density and high-precision PCB design, the line width needs to reach this value to ensure production quality and reliability. ‌

The minimum line width may vary under different design requirements. The minimum line width that can be supported may reach 3.5mil (about 0.09mm) or less, but in most common designs, the line width will be greater than this value to ensure production yield and reliability. ‌ In high-density and high-precision PCB design, the line width may be thinner. ‌

When designing a PCB, the choice of line width needs to consider the needs of signal transmission. Generally speaking, the larger the line width, the better the factory production and the higher the yield. The line width in conventional design is usually 10mil (about 0.254mm), which can meet most application scenarios. In high-speed signal transmission, the line width needs to be greater than 10mil to reduce signal loss and synchronization problems.

What is the minimum hole spacing for PCB?

The minimum hole spacing of PCB is generally 0.1mm to 0.15mm. This range is applicable to standard 6-layer PCB circuit boards, but the specific value may vary depending on the manufacturing process and design requirements.

Under different manufacturing processes, the specific value of the minimum hole spacing is different. The minimum aperture of mechanical drilling is 0.15mm, while the minimum aperture of laser drilling can reach 0.075mm. In addition, the spacing from the pad to the outline is generally 0.2mm, and the single side of the pad cannot be less than 4mil (about 0.1mm), preferably greater than 6mil (about 0.15mm). For non-metallic holes and slots, the minimum spacing is not less than 1.6mm, and the slot hole is not less than 2.0mm from the edge of the board of the outline.

Factors that affect the minimum hole spacing of PCB include manufacturing process, design requirements and drilling detection. The advancement of manufacturing process has continuously improved the accuracy of PCB boards, and the minimum hole diameter and spacing have been continuously reduced. For example, the accuracy of modern PCB boards has developed to a minimum hole diameter of 0.08 mm and a minimum hole spacing of 0.1 mm or even higher. In addition, drilling detection is also an important link to ensure the quality of PCBs, including through holes, part holes, slot holes and special-shaped holes, which all need to be strictly inspected.

Why is PCB trace spacing design so important?

PCB trace spacing design is very important because it is directly related to the reliability, performance and safety of the circuit board. By reasonably designing the trace spacing, electrical interference can be avoided, signal transmission quality can be guaranteed, and the thermal stability and reliability of the circuit board can be improved, thereby ensuring the normal operation and long-term stable operation of the circuit board.

First, the design of trace spacing can prevent electrical interference. When two traces are parallel and close to each other, parasitic capacitance and inductance will be generated between them, resulting in signal interference and attenuation. Increasing the trace spacing can reduce this coupling effect, thereby ensuring stable signal transmission.

Second, appropriate trace spacing helps to improve the thermal stability of the circuit board. Components and traces with large working current will generate heat when working. If the traces are too dense, heat is easy to accumulate, resulting in local temperature rise, which may cause failure.

In addition, the design of trace spacing also needs to consider the requirements of production process. Smaller line width and line spacing have higher requirements for production process, which may increase production difficulty and cost.

What will happen if the PCB trace spacing is insufficient?

Insufficient PCB trace spacing will lead to problems such as signal attenuation, signal delay, crosstalk interference and layout difficulties. These problems will affect the performance and stability of the circuit and may even cause circuit function failure.

First, signal attenuation is a major problem of insufficient spacing. Signals will be attenuated during transmission. Too small spacing will increase the possibility of signal attenuation, resulting in signal distortion and increased noise, especially in high-frequency signals and fast signal transmission.

Second, signal delay is also a problem caused by insufficient spacing. It takes time for signals to propagate in the circuit. Too small spacing will extend the path of signal propagation, thereby increasing signal delay and affecting the real-time performance of the system.

In addition, crosstalk interference is another important issue. Insufficient spacing will increase the electromagnetic interaction between signal lines, leading to crosstalk interference, thereby introducing errors or interference and affecting the stability of the circuit.

Finally, layout difficulties are also a practical problem caused by insufficient spacing. When laying out the PCB, too small spacing will increase the complexity of the layout, making it difficult for designers to reasonably arrange the signal path, the distribution of power and ground lines, and the layout of components.

Does trace spacing affect PCB production cost?

The setting of trace spacing is directly related to the difficulty and cost of PCB production process. Although smaller line width and spacing can improve the performance of the circuit, it will increase the difficulty and cost of production.

The setting principles of trace spacing include:

The default values of line width and spacing are usually 6mil, but they can be adjusted according to design requirements. The minimum line width recommended value is 10mil, and the maximum line width can be set to 200mil.

The setting of trace spacing needs to take into account electrical safety and signal integrity. It is usually required that the line center spacing is not less than 3 times the line width to ensure that the electric field does not interfere with each other.

In the design of high-speed signal lines, using larger spacing can further reduce crosstalk and improve the stability of the circuit, but it will also increase costs.

Factors that affect the cost of PCB production also include:

‌Number of wiring layers‌: The more layers, the higher the price.

‌Via size‌: Vias smaller than 0.25mm usually require additional fees, and back drilling will increase the cost by about 10%~20%.

‌Plate selection‌: Unconventional materials such as high-frequency plates and halogen-free plates will increase procurement cycles and production costs.

In summary, the setting of trace spacing has a significant impact on the cost of PCB production. Reasonable settings can control costs while ensuring performance.

In short, PCB line width and spacing are very important parameters in electronic circuit design. They directly affect the performance, reliability and manufacturing feasibility of the circuit board. When designing a circuit board, it is necessary to reasonably select line width and spacing according to the requirements of the circuit and the actual situation.

What is a regulator PCB?

Regulator PCB (Printed Circuit Board) is a printed circuit board that integrates regulator-related circuit components. It is centered on regulator components (such as voltage, current or power regulators), supplemented by other circuit components such as capacitors, resistors, and inductors to work together.

Through specific working principles, such as linear regulators adjust the degree of conduction, switching regulators use high-frequency switching actions and related modulation methods to achieve voltage regulation, current detection and control to achieve current regulation, and power regulation based on voltage and current regulation.

At the same time, it has output stability, can maintain output stability when the input voltage fluctuates and the load changes, and has multiple protection functions such as overvoltage, overcurrent, and overheating. It has the characteristics of flexible design of circuit structure and parameters according to needs, high integration to reduce volume, and easy installation and use.

What are the three types of regulators?

There are three main types of regulators: contact regulators, transistor regulators, and integrated circuit regulators. ‌

Contact regulators are an earlier type of regulator, which are characterized by slow contact vibration frequency, mechanical inertia and electromagnetic inertia, resulting in low voltage regulation accuracy, easy sparking of contacts, large radio interference, poor reliability, and short life. They have now been eliminated.

Transistor regulators emerged with the development of semiconductor technology. Their advantages include high switching frequency of transistors, no sparking, high regulation accuracy, light weight, small size, long life, high reliability, and low radio wave interference. This type of regulator is now widely used in a variety of mid- and low-end models.

In addition to the advantages of transistor regulators, integrated circuit regulators also have the characteristics of ultra-small size. They are usually installed inside the generator (built-in regulators), reducing external wiring and improving cooling effects. This type of regulator is widely used in a variety of car models.

What is an apex regulator pcb?

Apex regulator is an electronic device that regulates the voltage, current or power of a power supply to meet the needs of a specific electronic device or system. And the Apex regulator PCB is the product of combining the Apex regulator with the printed circuit board (PCB) technology.

PCB is a substrate that carries electronic components and provides electrical connections. It is made of insulating material, usually glass fiber reinforced epoxy, covered with a conductive copper foil pattern. Electronic components are mounted on the PCB by soldering or other connection methods to form a complete electronic circuit.

Apex regulator PCB integrates the Apex regulator onto the PCB, achieving a more compact and efficient power regulation solution. This integrated design not only reduces the space occupied, but also improves the reliability and stability of the circuit.

What is the function of the apex regulator pcb?

Receive input voltage: The PCB receives the input voltage from the power supply, which may vary due to a variety of factors. This input voltage is usually higher or lower than the level required by the system components.

Regulate voltage: The voltage regulator on the PCB adjusts the input voltage to match the required output level. If the input voltage is too low, the regulator increases it to the appropriate level.

Stabilizes output voltage: Once the voltage is regulated, the PCB distributes it to the various components of the electronic system. A feedback control system continuously monitors the output voltage to ensure it remains stable, and makes real-time adjustments as needed to offset any fluctuations in the input voltage.

Ensures lifespan: By maintaining a stable voltage supply, the apex regulator PCB helps protect sensitive components from damage caused by voltage surges or voltage drops.

How does a apex regulator circuit work?

The working principle of an APEX regulator PCB is to convert analog signals into digital signals through an ADC conversion circuit so that electronic devices and computers can understand and process them. ‌ This process involves converting analog signals from our real world into digital signals, allowing electronic devices to recognize and process these signals‌.

Specifically, the ADC conversion circuit in the APEX regulator PCB is responsible for converting the input analog signal into a digital signal. The ADC (Analog-to-Digital Converter) circuit is responsible for converting continuously changing analog voltage or current signals into discrete digital signals that can be processed and analyzed by electronic devices.

ADC circuits usually consist of three main parts: sampling, quantization, and encoding. These steps convert analog signals into binary codes that computers can process.

What are the applications for apex regulator pcb?

Apex regulator PCB is mainly used in automation industry, industrial robots, medical inspection, precision testing instruments and other fields. ‌ These application fields have high requirements for accuracy, efficiency and stability, making Apex regulator PCB an ideal choice.

In the automation industry, Apex regulator PCB is widely used in various automation equipment, such as servo system-controlled CNC trademark printing machines, CNC pipe bending machines, etc. These equipment require high-precision speed control and stable output. Apex regulator PCB can provide precise control and reliable performance to meet the needs of automated production.

In the field of industrial robots, Apex regulator PCB is used to control various actions of the robot to ensure its precise operation in complex environments. Its high torque output and stable accuracy enable the robot to perform well in various industrial applications, improving production efficiency and product quality.

Medical inspection and precision testing instruments also require regulators with high accuracy and stability. The application of Apex regulator PCB in these fields can provide precise control signals to ensure the accuracy and reliability of test results.

Conclusion:

As an indispensable part of electronic equipment, Apex regulator PCB plays an irreplaceable role in ensuring stable operation of equipment and improving equipment performance. With the continuous development of technology, it will continue to develop in the direction of miniaturization, integration, high efficiency, intelligence, etc., and continue to play an important role.

Is the circuit board DC or AC?

Circuit boards can transmit both direct current and alternating current. In modern electronic products, we use alternating current for power supply, so most circuit boards are also designed to transmit alternating current. Of course, in some special application scenarios, some circuit boards also need to transmit direct current. Whether transmitting direct current or alternating current, the circuit board needs to meet the requirements of the transmitted current.

What is the PCB in AC?

The alternating current in PCB refers to the current whose direction changes periodically, that is, alternating current (AC). The application of alternating current in PCB is mainly reflected in power conversion and power transmission. PCB power supply usually converts AC into stable direct current (DC) output to meet the demand of electronic equipment for stable power supply. PCB power supply converts AC into the required DC through components such as transformers, rectifiers, filters and voltage regulators, and provides stable power output.

How to calculate the bandwidth of AC in PCB traces

The calculation of AC PCB trace width can be performed by the following formula: W = (I / J) * K, where W represents the trace width, I represents the current, J represents the current density, and K represents a coefficient related to materials and processes. ‌This formula shows that the trace width is related to the current, current density, and material properties‌.

AC in PCB Design Guide

Current Carrying Capacity: The width of a trace directly affects its ability to handle current without exceeding temperature limits or causing excessive voltage drop.
‌Impedance Control: In high-frequency applications, maintaining controlled impedance is critical for signal integrity. Trace width, trace spacing, and dielectric properties affect the characteristic impedance of the transmission line.
‌Heat Dissipation: Adequate trace width helps to effectively dissipate heat, preventing thermal issues such as trace delamination or solder joint failure.
‌Voltage Drop: Narrower traces exhibit higher resistance, resulting in increased voltage drop along the length of the trace. By adjusting the trace width, the voltage drop can be minimized.
‌Manufacturability: The PCB manufacturing process imposes restrictions on the minimum trace width, and designers must balance performance requirements with manufacturability constraints. ‌2.
‌Minimum Trace Width: Most manufacturers have a minimum trace width of 6mil or 0.152mm, and typically use traces of 0.254-0.3mm.
‌Material and Process Deviations: Due to the possibility of material and process deviations in the actual PCB manufacturing process, a certain margin needs to be left when calculating the line width.
‌Signal Integrity Simulation‌: Perform signal integrity simulations to ensure impedance is controlled and signal degradation due to reflections, crosstalk, or transmission line effects is minimized‌

AC in PCB wiring

The current trend is that the power supply voltage is getting lower and lower (especially for highly integrated digital devices), the space occupied is getting smaller and smaller, the weight is getting lighter and lighter, and the efficiency is getting higher and higher, which requires the precise design of the power supply circuit starting from the PCB.

Safety distance includes electrical clearance (spatial distance), creepage distance (surface distance) and insulation penetration distance…

Electrical clearance: the shortest distance between two adjacent conductors or one conductor and the adjacent motor housing surface measured along the air.
Creepage distance: the shortest distance between two adjacent conductors or one conductor and the adjacent motor housing surface measured along the insulation surface.

Determination of electrical clearance:

The distance can be determined according to the measured working voltage and insulation level

The electrical clearance size requirements of the primary side line are shown in Table 3 and Table 4

The electrical clearance size requirements of the secondary side line are shown in Table 5

But usually: Primary side AC part: L-N ≥ 2.5mm before the fuse, L.N PE (earth) ≥ 2.5mm, no requirements are made after the fuse is installed, but a certain distance should be maintained as much as possible to avoid short circuit damage to the power supply.

Primary side AC to DC part ≥2.0mm

Primary side DC ground to earth ≥2.5mm (primary side floating ground to earth)

Primary side to secondary side ≥4.0mm, components connected between primary and secondary sides

Secondary side gap ≥0.5mm

Secondary side ground to earth ≥1.0mm

Note: Before determining whether it meets the requirements, the internal parts should be applied with a force of 10N and the outer shell with a force of 30N to reduce the distance so that the space distance still meets the requirements under the worst case.

Determination of creepage distance:

Based on the working voltage and insulation level, the creepage distance can be determined by looking up Table 6

But usually: (1), primary side AC part: L-N ≥2.5mm before the fuse, L.N earth ≥2.5mm, no requirement is required after the fuse, but try to keep a certain distance to avoid short circuit damage to the power supply.

(2) Primary side AC to DC part ≥2.0mm

(3) Primary side DC ground to ground ≥4.0mm such as primary side ground to earth

(4) Primary side to secondary side ≥6.4mm, such as optocoupler, Y capacitor and other components, the foot spacing ≤6.4mm needs to be slotted.

(5) Secondary side parts ≥0.5mm

(6) Secondary side ground to earth ≥2.0mm or more

(7) Transformer two-stage ≥8.0mm or more

Insulation penetration distance:

It should meet the following requirements according to the working voltage and insulation application:

For working voltage not exceeding 50V (71V AC peak or DC value), there is no thickness requirement;
The minimum thickness of additional insulation should be 0.4mm;
When the reinforced insulation is not subjected to any mechanical stress that may cause deformation or performance degradation of the insulating material at normal temperature, the minimum thickness of the reinforced insulation should be 0.4mm. If the insulation provided is used in the protective casing of the equipment and will not be bumped or scratched during maintenance by the operator, and any of the following conditions apply, the above requirements do not apply to thin insulating materials regardless of their thickness;
For additional insulation, at least two layers of material are used, each of which can pass the dielectric strength test for additional insulation; or:
For additional insulation composed of three layers of material, any combination of two layers of material can pass the dielectric strength test for additional insulation; or:
For reinforced insulation, at least two layers of material are used, each of which can pass the dielectric strength test for reinforced insulation; or:
For reinforced insulation composed of three layers of insulating material, any combination of two layers of material can pass the dielectric strength test for reinforced insulation.

Points to note about wiring process:

Flat components such as capacitors must be flat without glue.

If the distance between two conductors can be shortened by applying a force of 10N, which is less than the safety distance requirement, glue can be used to fix the part to ensure its electrical clearance.

When laying PVC film inside some shell equipment, attention should be paid to ensuring the safety distance (pay attention to the processing technology).

When fixing the parts with glue, be careful not to leave foreign matter such as glue wire on the PCB board.

When processing parts, insulation damage should not be caused.

Requirements for flame-proof materials:

Heat shrink tubing V-1 or VTM-2 or above; PVC tubing V-1 or VTM-2 or above

Teflon tubing V-1 or VTM-2 or above; plastic materials such as silicone sheets, insulating tape V-1 or VTM-2 or above

PCB board 94V-1 or above

Regarding insulation level

(1) Working insulation: insulation required for normal operation of equipment

(2) Basic insulation: insulation that provides basic protection against electric shock

(3) Supplementary insulation: independent insulation applied in addition to basic insulation to protect against electric shock in case of basic insulation failure

(4) Double insulation: insulation consisting of basic insulation plus supplementary insulation

(5) Reinforced insulation: a single insulation structure that provides the same level of protection against electric shock as double insulation under the conditions specified in this standard

The applicable situations of various insulation are as follows:

A. Operational insulation

a. Between parts with different voltages

b. Between ELV circuits (or SELV circuits) and grounded conductive parts.

B. Basic insulation

a. Between parts with dangerous voltages and grounded conductive parts;

b. Between SELV circuits with dangerous voltages and grounding-dependent;

c. Between the primary power conductor and the grounded shield or the core of the main power transformer;

d. As part of double insulation.

C. Supplementary insulation.

a. Generally speaking, between accessible conductive parts and parts that may carry dangerous voltages after basic insulation is damaged, such as:

Ⅰ. Between the surface of handles, knobs, handles or similar objects and their ungrounded axis.

Ⅱ. Between the metal casing of the second category equipment and the outer skin of the power cord passing through this casing.

Ⅲ. Between the ELV circuit and the ungrounded metal casing.

b. As part of double insulation

D. Double insulation

Double insulation Reinforced insulation

Generally speaking, between the primary circuit and

a. between accessible ungrounded conductive parts, or

b. between floating SELV circuits, or

c. between TNV circuits

Double insulation = basic insulation + supplementary insulation

Note: ELV circuit: extra low voltage circuit

Under normal working conditions, the AC peak value between conductors or between any conductors does not exceed 42.4V or the DC value does not exceed 60V.

SELV circuit: safety extra low voltage circuit.

A properly designed and protected secondary circuit so that under normal conditions or single fault conditions, the voltage between any two accessible parts, and between any accessible parts and the protective grounding terminal of the equipment (only for Class I equipment) will not exceed the safety value.

TNV: communication network voltage circuit

Under normal working conditions, the circuit carrying communication signals

Difference between direct current and alternating current

‌The main differences between DC and AC include direction and polarity, voltage change, current loss, transformer use, and application scenarios.

‌Direction and polarity:

DC: The direction of the current remains unchanged, and the electrons flow from the positive electrode to the negative electrode.

AC: The direction of the current changes periodically, and the electrons flow back and forth between the positive and negative electrodes. ‌
‌Voltage change:

DC: The voltage remains constant and does not change over time.

AC: The voltage magnitude and direction change periodically over time. For example, the mains is an AC with a sine waveform.

‌Current loss:

DC: Fault losses are relatively small.

AC: There is capacitive current, and there is capacitive current in the transmission line. ‌
‌Transformer use:

DC: The voltage cannot be changed using a transformer.

AC: The voltage can be changed using a transformer, which is suitable for boosting voltage to reduce losses during long-distance transportation.

‌Application scenarios:

DC: Suitable for low-voltage electrical appliances and occasions that require stable current.
‌Alternating current‌: Suitable for household and industrial use, using transformers to change voltage to suit different needs.‌

FAQ About AC in PCB

FAQ About AC in PCB

Q: The relationship between PCB current and line width. Is the current divided into AC or DC?
A: The relationship between PCB current and line width is not divided into AC or DC. In terms of the nature of the lines on the PCB, the lines are all made of copper materials, and both AC and DC can pass. However, how much current can pass depends on the cross-sectional area of the line on your PCB. That is, line width x thickness of the copper foil of the line. If the cross-sectional area of the line is small, only small current signals can pass, and if the cross-sectional area is large, large current signals can pass. This signal can be AC or DC.
Not just 1mm, any line width can pass DC or AC signals.

Q: There is a packaged device, and there are 2 pins in the device that need to be connected to the live wire and neutral wire of 220V AC respectively. So how to deal with this power line when drawing the PCB? Are there any size requirements for pads, wires, etc.? Are there any protective measures required? Is it not possible to directly add pads to connect to the pin pads of the device?
A: It is best to mill a groove between the neutral wire and the live wire, and choose the thickness of the wire according to the current. When the current is large, you can put a tin layer on the wire, and the pad should be slightly larger.

Q: The grounding of the PCB circuit board design is also the negative pole. What is the difference between the grounding here and the AC grounding?

A: The concept of the circuit board ground is somewhat different from that of the power supply system. The power supply system refers to the earth, that is, the terminal with the same potential as the earth.

The ground in the circuit board is just a common terminal of a potential, which can be positive or negative, depending on the needs of the designer. It’s just that everyone is used to and assumes that the negative pole is the common terminal, that is, the ground. The circuit board ground is not necessarily connected to the earth.

But it must be connected to the earth when EMI filtering is required.

Q: Should all GNDs on the PCB board be connected? There is a terminal (screw type) with two terminals marked as V1+ and V1- on the PCB schematic. Should V1- be connected to the power supply ground? But I used a multimeter to measure why V3- is not connected to other GNDs on the board?

So how do you connect the ground and 10V of the power supply to the V1+ and V1- ends of the terminal?

A: Not all ground wires on the board are connected together. The ground wires are divided into analog ground and digital ground, just like the ground wire in DC and the ground wire in AC cannot be connected together. That is to say, there is a ground wire that is specifically used for power supply, and there is a ground wire that is specifically used for signals (shielding signal interference). These two ground wires cannot be connected together.
In addition, you mentioned V1+ and V1-, and V1- should not be considered a ground wire. Generally, the signal represented by this method is a differential signal, that is, the V1 signal is differentially divided into V1+ and V1-, which can reduce external interference and transmit farther. Finally, V1+ and V1- are integrated into the V1 signal.
You need to figure out whether the V1+ and V1- of the terminal are used for power supply. If they are used for power supply, then V1+ is the positive pole. V1- is the negative pole. Since you didn’t show us the picture, you can’t just connect it randomly. The circuit board needs to connect not only power but also signals, depending on how your board is made.

How good is aluminum at conducting heat?

Aluminum has relatively good thermal conductivity, but its thermal conductivity is not as good as copper. The thermal conductivity of aluminum is about 237 W/m·K, while the thermal conductivity of copper is about 385 W/m·K, which means that under the same conditions, copper can transfer heat more efficiently.

What is the thermal conductivity of aluminum?

The reason why aluminum has good thermal conductivity is that its thermal conductivity is high, and aluminum has a high specific heat capacity. Specific heat capacity refers to the amount of heat that needs to be absorbed or released by a unit mass of a substance to increase or decrease the temperature by 1K. Aluminum’s high specific heat capacity makes it more efficient in absorbing and releasing heat, which is crucial for applications that need to dissipate heat quickly.

What is thermal conductivity?

Thermal conductivity is a physical quantity that represents the ability of a material to conduct heat. The higher the thermal conductivity, the less heat is lost within the material. Thermal conductivity is defined as the amount of heat directly conducted through a material per unit cross-section and length per unit temperature difference and per unit time, and is expressed in Watts per meter Kelvin (W/m-K).

What is the thermal heat conductivity of aluminium?

The thermal conductivity of aluminium is 237W/mK. Thermal conductivity (k) is a measure of the ability of heat to flow through a material.

Thermal conductivity (k) is a measure of the ability of a material to conduct heat, and represents the amount of heat flow through a unit area per unit temperature gradient per unit time. Aluminium, as a common metal material, has a high thermal conductivity and is suitable for applications that require good thermal conductivity.

What is the thermal conductivity of aluminium at high temperatures?

The thermal conductivity of aluminium changes as the temperature increases. Generally speaking, as a metal gets hotter, its thermal conductivity decreases slightly. For aluminium, the thermal conductivity decreases as the temperature increases, but it still retains significant thermal conductivity.

As temperatures approach 500°C, the thermal conductivity of aluminum drops to about 160 W/m·K. This drop occurs because increasing temperatures cause increased atomic vibrations within the metal, which interferes with the flow of heat. Despite this drop in thermal conductivity, aluminum still performs well in high-temperature applications, such as engines or high-performance electronics.

What is the weight constant of aluminum?

The weight constant of aluminum is 2.7 g/cm³. Aluminum is a metallic element with a silvery-white appearance and is a lightweight metal.

The density of aluminum can also be expressed as 2.7×10³ kg/m³, which means that there are 2.7×10³ kg per cubic meter of aluminum. 34 In addition, the density of aluminum can also be expressed as 2700 kg/m³, which is another common unit conversion method.

What is the K value of aluminum?

The “K” value is a shorthand term that is often used to refer to the thermal conductivity of a material. The thermal conductivity K value of aluminum is 237 W/mK. Aluminum is a common metal material with a thermal conductivity of 237W/mK in the solid state.

Thermal conductivity (thermal conductivity coefficient) is a physical property of a material that indicates the ability of heat to be conducted through a unit area and temperature gradient in a unit time. The greater the thermal conductivity, the better the thermal conductivity of the material. Aluminum, as an excellent thermal conductive material, is widely used in many applications.

What would a high value of K mean thermal conductivity?

A high K value means that the thermal conductivity of the material is high, that is, the material has a strong ability to conduct heat. Thermal conductivity (K value) is an important parameter to measure the rate and ability of a material to conduct heat. Materials with high K values can conduct heat more efficiently and have better thermal conductivity.

Specifically, thermal conductivity (K value) is defined as the amount of heat directly conducted by a material of unit cross-section and length under unit temperature difference and unit time. The metric unit is watt/meter Kelvin (W/m·K). If the K value of a material is 1, it means that when the temperature difference between the opposite surfaces is 1 degree, 1 cubic meter of the material will conduct heat at a rate of 1 watt.

Materials with high K values have significant advantages in thermal management. First, they can quickly transfer heat from the heat source to the heat sink, effectively reducing the operating temperature of electronic components, extending the life of the device, and improving system reliability. Second, materials with high K values can significantly reduce the thermal resistance between thermal interfaces and improve the efficiency of heat transfer, especially for high power density devices. Finally, in harsh working environments, materials with high K values can significantly enhance thermal management capabilities, prevent local overheating, and ensure stable system operation.

Is a higher or lower k value better?

Generally speaking, for applications that require effective conduction or heat dissipation, the higher the K value, the better. If the material has a higher K value, it can transfer heat away from hot spots faster, helping to prevent overheating.

In the electronics industry, components can get very hot, so people use materials with high thermal conductivity to make heat sinks. These materials can draw heat away from delicate parts, helping to prevent component damage or failure.

However, in some cases, the lower the thermal conductivity, the better. In insulating materials, you want a lower K value so that heat can’t pass through easily. In these cases, materials such as plastic or fiberglass, which have much lower thermal conductivity than aluminum, are preferred.

Conclusion:

With the continuous advancement of science and technology, the understanding and application of aluminum’s thermal conductivity will continue to expand and deepen. New processing technologies may further optimize aluminum’s thermal conductivity, allowing it to play a unique role in more emerging fields, such as new energy development and high-speed rail transportation.

How to convert Cadence17.2’s .brd file to HyperLynx9.4.1’s .hyp file

How to convert Cadence17.2’s .brd file to HyperLynx9.4.1’s .hyp file?Recently, I used Hyperlynx to simulate the signal integrity of PCBs, and I needed to convert various PCB formats into .hyp formats. In the process, I found that the PCB drawn by AD can be directly exported in .hyp format, which is very convenient, but the PCB drawn by Cadence cannot be directly exported. I need to use the built-in PCB converter of Hyperlynx to convert the .brd file of Cadence, as shown below:

But the conversion has always failed. I checked the .ERR file and found a line like this: ERROR: Cadance Allegro utility:extracta, so it is a problem with extracta.exe.

The specific solution is to add the system variable CDSROOT, and the value is D:\Cadence\Cadence_SPB_17.2-2016\tools\bin (the location of your extracta.exe). After confirming, restart the computer and the problem is solved.

Tutorial on converting Cadence17.2’s .brd file to HyperLynx9.4.1’s .hyp file

Tutorial on converting Cadence17.2’s .brd file to HyperLynx9.4.1’s .hyp file?Open the PCB file in Allegro, select ODB++inside in file–>export, select Export as ODBV6, click 1, and then click Accept….

HyperLynx’s built-in conversion function can directly convert Allegro’s .brd file for use, but for some reason the following error always occurs. I didn’t find a solution online, so I had to find another way.

Another way to import PCB into HyperLynx is to convert the file to ODB++inside format. This method requires the installation of the ODB++inside plug-in in advance.

After installing the plug-in, you can convert the .brd file.
First open the PCB file in Allegro, select ODB++inside in file–>export, the following figure appears, select Export as ODBV6, click 1, and then click Accept.

Wait for the conversion to succeed.

This file is the converted file
Open HyperLynx9.4.1, select open ODB++ in file, select the odbjob_v6 folder, and click select folder.

Wait to open.

Click ok. .

What is a .hyp file?

.hyp file is a file used to record key information such as boundary conditions, material properties, solver settings, etc. of the analysis. ‌ This file is usually associated with HyperWorks analysis software and is the basis for numerical calculation and analysis.

The specific uses of .hyp files include:

‌Geometry model file‌: represents the geometry of the product or structure.
‌Mesh file‌: shows the process of dividing the model into finite elements.
‌Simulation setting file‌: records the key setting information of the analysis.
‌Result file‌: contains the calculated engineering quantities such as strain, stress, displacement, etc.
‌Post-processing file‌: used to visualize and analyze results in tools such as HyperView.
‌Report document‌: usually in PDF or Word format, recording detailed results and conclusions of the analysis‌1.
In terms of use, for example, in PCB tool software, .hyp files can be created and edited through the BroadSim function, including setting line characteristics, editing stacking information, etc., to simulate and analyze circuit boards‌2. In addition, the Hype software also supports exporting to .hyp format files for further analysis and processing.

What are the holes in a PCB called?

What are the holes on PCB called? What are the holes in the circuit? The holes on PCB can be roughly divided into 3 types, screw holes (mounting holes), conductive holes (vias), and plug-in holes.

Screw holes: Screw holes are used for fixing.

Conductive holes: Conductive holes (also called vias) are used for conducting electricity just like circuits.

Plug-in holes: Plug-in holes are of course used to plug in various parts, such as diodes, transistors, capacitors, inductors, etc.

What is a through hole

What is a through hole? Through holes, also known as perforations, are holes in a PCB that go all the way through the board. Their main purpose is to provide electrical connections for component pins while allowing soldering on both sides of the board.

1.A via is a special through hole whose wall is metallized to achieve electrical connection between different layers on a circuit board. This type of hole is usually used to connect component pins to internal circuits, or to achieve electrical connection between different layers in a multi-layer PCB. Vias need to be metallized during the PCB manufacturing process, which usually includes drilling, desmearing, chemical copper plating, and electroplating.

2.Non-conducting holes are the opposite of through holes. Their hole walls are not metallized, so they do not have electrical connection functions. These holes are mainly used for mechanical fixation, heat dissipation or identification purposes. Non-conducting holes are relatively simple in the PCB manufacturing process, and only drilling operations are required.

What is a blind via?

A blind via is a hole that extends from one side of a PCB to a certain internal layer without penetrating the entire board. The emergence of blind vias is mainly due to the development of HDI technology, which provides circuit designers with greater flexibility and more compact layout. Blind vias are usually used to connect surface mount components (SMD) to internal circuit layers, or to connect circuits between different internal layers.

What are buried vias?

Buried vias are holes located inside the PCB that do not penetrate any side of the board. They are completely hidden inside the board and are used to connect circuits between different internal layers. Buried vias are especially useful in HDI boards because they can reduce the overall thickness of the board while maintaining electrical connections between internal circuits.

What is a microvia?

Microvia refers to a hole with a smaller diameter, usually at the micron level. The emergence of microvia technology enables PCB designers to achieve more complex circuit layouts in a smaller space. Microvias are often used in high-density, high-reliability electronic devices such as mobile phones and tablets. The manufacture of microvias requires high-precision drilling equipment and technology to ensure the accuracy and reliability of the holes.

What are Mounting holes？

What are Mounting holes?Locking holes are auxiliary holes used in the PCB manufacturing and assembly process to accurately locate and fix the circuit board. They are usually located at the edge or specific position of the PCB to ensure that the circuit board can be accurately aligned and fixed during manufacturing, testing and assembly. The locating holes do not participate in the connection of the circuit, but are essential to ensure the quality and performance of the circuit board.

What are Mounting holes？

What are thermal vias?

Thermal vias are holes designed specifically for heat dissipation, usually large and can run through the entire PCB or multiple layers. Their role is to reduce heat buildup on the circuit board by increasing surface area and air flow, thereby improving the stability and reliability of the device. Thermal vias are particularly important in high-performance, high-power electronic devices.

FAQ About board electronics with holes

How to solve the contradiction between manual routing and automatic routing of high-speed signals?

Most of the current powerful routing software’s automatic routing tools have set constraints to control the routing method and the number of vias. The routing engine capabilities and constraint setting items of various EDA companies are sometimes very different. For example, whether there are enough constraints to control the winding method of the serpentine, whether the routing spacing of the differential pair can be controlled, etc. This will affect whether the routing method generated by automatic routing can meet the designer’s ideas. In addition, the difficulty of manually adjusting the routing is also related to the capabilities of the routing engine. For example, the pushing ability of the routing, the pushing ability of the via, and even the pushing ability of the routing pair copper. Therefore, choosing a routing tool with strong routing engine capabilities is the solution.

Will adding test points affect the quality of high-speed signals?

As for whether it will affect the signal quality, it depends on the method of adding test points and how fast the signal is. Basically, the additional test points (not using the existing vias (via or DIP pins) as test points) may be added to the line or a small section of wire may be pulled out from the line. The former is equivalent to adding a very small capacitor to the line, while the latter is an additional branch. Both of these situations will have some impact on high-speed signals, and the extent of the impact is related to the frequency speed of the signal and the edge rate of the signal. The magnitude of the impact can be learned through simulation. In principle, the smaller the test point, the better (of course, it must meet the requirements of the test equipment) and the shorter the branch, the better.

Can you introduce some foreign technical books and data on high-speed PCB design?

Now the application of high-speed digital circuits includes communication networks and calculators and other related fields. In the communication network, the operating frequency of PCB boards has reached around GHz, and the number of layers is as many as 40 layers as far as I know. Due to the advancement of chips, the operating frequency of calculator-related applications, whether it is a general PC or server, has reached 400MHz (such as Rambus) or above. In response to the demand for high-speed and high-density routing, the demand for blind/buried vias, mircrovias and build-up process technology is gradually increasing. These design requirements can be mass-produced by manufacturers.

Does the design of rigid-flexible boards require special design software and specifications? Where can I undertake the processing of such circuit boards in China?

Can I use general PCB design software to design flexible printed circuits (Flexible Printed Circuit). The Gerber format is also used for FPC manufacturers to produce. Since the manufacturing process is different from that of general PCBs, each manufacturer will have its own restrictions on line width, line spacing, and aperture (via) based on their manufacturing capabilities. In addition, some copper foil can be laid at the turning point of the flexible circuit board for reinforcement. As for the manufacturer, you can search for “FPC” as a keyword on the Internet and you should be able to find it.

If the size of the circuit board is fixed, if the design needs to accommodate more functions, it is often necessary to increase the routing density of the PCB, but this may lead to increased mutual interference between the routings, and at the same time, the impedance cannot be reduced if the routing is too thin. Please introduce the techniques in the design of high-speed (>100MHz) high-density PCBs?

When designing high-speed and high-density PCBs, crosstalk interference does need to be paid special attention to because it has a great impact on timing and signal integrity. Here are a few things to note:

Control the continuity and matching of the characteristic impedance of the trace.

The size of the trace spacing. The spacing commonly seen is twice the line width. Through simulation, you can know the impact of trace spacing on timing and signal integrity and find the tolerable spacing. The results of different chip signals may be different.

Choose an appropriate termination method.

Avoid the same routing direction of the upper and lower adjacent layers, or even have traces overlapped up and down, because this kind of crosstalk is greater than the case of adjacent traces on the same layer.

Use blind/buried vias to increase the trace area. However, the production cost of the PCB board will increase. It is indeed difficult to achieve complete parallelism and equal length in actual implementation, but it should be done as much as possible.

In addition, differential termination and common mode termination can be reserved to mitigate the impact on timing and signal integrity.

The RF part, IF part, and even the low-frequency circuit part of the outdoor unit are often deployed on the same PCB. What are the material requirements for such PCB? How to prevent interference between RF, IF, and even low-frequency circuits?

Hybrid circuit design is a big problem. It is difficult to have a perfect solution.

Generally, RF circuits are laid out and wired as an independent single board in the system, and there will even be a special shielding cavity. Moreover, RF circuits are generally single-sided or double-sided boards, and the circuits are relatively simple. All of these are to reduce the impact on the distributed parameters of RF circuits and improve the consistency of RF systems. Compared with general FR4 materials, RF circuit boards tend to use high-Q substrates. The dielectric constant of this material is relatively small, the distributed capacitance of the transmission line is small, the impedance is high, and the signal transmission delay is small. In hybrid circuit design, although RF and digital circuits are made on the same PCB, they are generally divided into RF circuit area and digital circuit area, and laid out and wired separately. Shielding is used between ground vias and shielding boxes.

‌What is a high frequency pcb communication circuits

High frequency pcb communication circuits to a circuit board with an operating frequency in the high frequency band (usually greater than 300MHz or a wavelength less than 1 meter), which is mainly used to transmit high-frequency signals and data. ‌ This type of circuit board is widely used in radio frequency (RF) and microwave fields, such as communication equipment, radar systems, satellite communications, and high-speed data transmission systems.

What is a high frequency pcb communication circuits

The characteristics of high-frequency circuits include challenges such as transmission line effects, signal integrity issues, and electromagnetic interference (EMI). Due to the short wavelength of high-frequency signals, traditional low-frequency circuit design methods are no longer applicable, and special design and processing methods are required to ensure the performance and stability of the circuit.

High-frequency circuit boards are produced on microwave substrate copper-clad boards using ordinary rigid circuit board manufacturing methods or special processing methods. They need to have high-quality electrical properties and chemical stability to meet the requirements of high-frequency signal transmission.

Definition of high frequency pcb communication circuits

High-frequency circuit board, as a special circuit board, is mainly suitable for occasions with high electromagnetic frequency, especially in the fields of high frequency (frequency greater than 300MHz or wavelength less than 1 meter) and microwave (frequency greater than 3GHz or wavelength less than 0.1 meter).

It is a circuit board made on a microwave substrate copper-clad board by adopting some manufacturing processes or special processing methods of ordinary rigid circuit boards. Generally speaking, when the frequency of the circuit board reaches above 1GHz, it can be defined as a high-frequency board.

With the rapid development of science and technology, more and more equipment designs have begun to involve microwave frequency bands (>1GHz) and even expanded to the millimeter wave field (such as 77GHz), especially in popular applications such as 77GHz millimeter wave antennas on vehicles.

This trend not only promotes the continuous increase in frequency, but also puts higher requirements on the substrate of the circuit board.

For example, the substrate material needs to have excellent electrical properties, stable chemical properties, and as the frequency of the power signal increases, the loss on the substrate must be extremely small. Therefore, the importance of high-frequency boards is becoming more and more prominent.

Advantages of high frequency pcb communication circuits

The main advantages of high frequency pcb communication circuits include efficient data transmission, strong anti-interference ability, high-frequency bandwidth and high reliability. ‌

high frequency pcb communication circuits can achieve efficient data transmission. High-frequency signals have a short cycle and can transmit more information per unit time, so they have the advantage of large-capacity transmission. In addition, high-frequency signals can achieve fast signal processing and are suitable for application scenarios that require high-speed data transmission and high real-time requirements.
high frequency pcb communication circuits have strong anti-interference capabilities. Due to the short wavelength of high-frequency signals, they can better avoid external interference and attenuation and have strong anti-interference capabilities. This makes high-frequency signals have advantages in fields such as wireless communications and radar systems, and can achieve stable signal transmission and reception. ‌
high frequency pcb communication circuits also have the advantage of high-frequency bandwidth. High-frequency signals correspond to a larger frequency range and can provide higher bandwidth than low-frequency signals. This means that more data can be transmitted, thereby supporting higher data rates and richer media content. ‌
High reliability of high frequency pcb communication circuits is also one of its advantages. The use of high-quality materials and manufacturing processes can effectively resist external interference and oxidation corrosion, ensure stable performance in high temperature environments, and thus extend the service life of the circuit board.

Classification of high frequency pcb communication circuits

Classification by material:

Organic materials: including phenolic resin, glass fiber/epoxy resin, Polyimide, BT/Epoxy (bismaleimide triazine/epoxy resin), etc.
Inorganic materials: mainly including aluminum, copper-invar-copper, ceramic, etc. These materials are mainly selected for their excellent heat dissipation function.

Classification by the hardness of the finished product:

Rigid PCB: has a solid structure and stable performance.
Flexible PCB: has flexibility and bendability, suitable for occasions requiring flexible wiring.
Rigid-Flex PCB: It combines the characteristics of rigid and flexible boards, and has higher design flexibility and wide application.

Classification by structure:

Single-sided board: A circuit board with a conductive layer on only one side.
Double-sided board: Both sides are coated with conductive layers, separated by insulating materials in the middle.
Multilayer board: It is composed of multiple conductive layers and insulating layers, and has higher circuit integration and reliability.

Classification by use:

Communication board: It is used in various communication equipment and systems.
Consumable electronic board: It is commonly found in consumer electronic products.
Military board: A circuit board that meets special requirements in the military field.
Computer board: A circuit board used in computer hardware.
Semiconductor board: A circuit board used in the manufacturing and testing process of semiconductors.
Electrical test board: A circuit board used in electronic testing and measurement equipment.

How to choose high-frequency circuit board high-speed board

When choosing PCB board, you must find a balance between meeting design requirements, mass production and cost. In short, the design requirements cover two aspects: electrical performance and structural reliability. Especially when designing ultra-high-speed PCB (frequency greater than GHz), the choice of board is particularly important. For example, the commonly used FR-4 material will have a significantly increased dielectric loss (Df, i.e., Dielectric Loss) at a frequency of several GHz, and may no longer be applicable.

Taking the 10Gb/S high-speed digital signal as an example, this signal can be regarded as the superposition of multiple sinusoidal wave signals of different frequencies. Therefore, the 10Gb/S signal contains multiple components of different frequencies: such as a 5GHz fundamental signal, a 3rd-order 15GHz signal, a 5th-order 25GHz signal, and a 7th-order 35GHz signal. In order to ensure the integrity of digital signals, maintain the steepness of the upper and lower edges of the signals, and be compatible with the low-loss, low-distortion transmission of RF microwaves (the high-frequency harmonic part of the digital signal reaches the microwave frequency band), the selection of materials for high-speed digital circuit PCBs has many similarities with the needs of RF microwave circuits.

In actual engineering operations, the selection of high-frequency boards seems simple, but the factors that need to be considered are quite complex. Through the introduction of this article, PCB design engineers or high-speed project leaders can have a deeper understanding of the characteristics and selection of boards. Understand the electrical properties, thermal properties, reliability and other characteristics of the board, and use the stacking design reasonably to create products with high reliability and excellent processability, and achieve the best balance of various factors.

Composition and key components of high frequency pcb communication circuits

High frequency pcb communication circuits are basically composed of passive components, active devices and passive networks. Passive components include resistors, capacitors and inductors, which mainly exhibit resistance characteristics at low frequencies, but also exhibit reactance characteristics at high frequencies. Active devices such as high-frequency triodes have the characteristics of high gain, high frequency response and low noise, and are widely used in television, radio communication, radar and other fields.

Application of high frequency pcb communication circuits

High frequency pcb communication circuits are widely used in long-distance communication systems, with a communication distance of up to thousands of kilometers, and are often used to maintain communication between aircraft and bases. It occupies a high-frequency band of 2~30MHz, uses skywave propagation, and can propagate over long distances. Modern airborne high-frequency communication systems usually use single-sideband communication systems, which can greatly compress the occupied frequency band and save transmission power. However, high-frequency communication is also susceptible to electrical interference such as ionospheric disturbances and lightning, generating radio background noise, and there is fading, and the signal is sometimes strong and sometimes weak.

Design Guidelines for High Frequency PCB Communication Circuits

Design Guidelines

High Frequency PCB Communication Circuits

How to avoid high-frequency interference?

The basic idea of avoiding high-frequency interference is to minimize the interference of the electromagnetic field of high-frequency signals, which is the so-called crosstalk. You can increase the distance between high-speed signals and analog signals, or add ground guard/shunt traces next to analog signals. Also pay attention to the noise interference of digital ground to analog ground.

How to solve the signal integrity problem in high-frequency communication PCB design?

Signal integrity is basically an impedance matching problem. The factors that affect impedance matching include the architecture and output impedance of the signal source, the characteristic impedance of the trace, the characteristics of the load end, and the topology of the trace. The solution is to rely on termination and adjust the topology of the trace.

How is the differential wiring method implemented?

There are two points to note when wiring differential pairs. One is that the length of the two lines should be as equal as possible, and the other is that the spacing between the two lines (this spacing is determined by the differential impedance) should remain unchanged, that is, they should be kept parallel. There are two parallel methods, one is that two lines run on the same routing layer (side-by-side), and the other is that two lines run on two adjacent layers (over-under). Generally, the former side-by-side (side by side, shoulder to shoulder) is more commonly used.

How to implement differential routing for clock signal lines with only one output end?

To use differential routing, it must be meaningful if both the signal source and the receiving end are differential signals. Therefore, differential routing cannot be used for clock signals with only one output end.

Can a matching resistor be added between the differential line pairs at the receiving end?

The matching resistor between the differential line pairs at the receiving end is usually added, and its value should be equal to the value of the differential impedance. This will improve the signal quality.

Why should the routing of differential pairs be close and parallel?

The routing method of differential pairs should be appropriately close and parallel. The so-called appropriate proximity is because this spacing will affect the value of differential impedance, which is an important parameter for designing differential pairs. Parallelism is also required because the consistency of differential impedance must be maintained. If the two lines are sometimes far away and sometimes close, the differential impedance will be inconsistent, which will affect the signal integrity and timing delay.

How to deal with some theoretical conflicts in actual wiring?

Basically, it is right to separate the analog/digital ground. It should be noted that the signal routing should try not to cross the split place (moat), and the return current path of the power supply and signal should not be too large.

The crystal oscillator is an analog positive feedback oscillation circuit. To have a stable oscillation signal, the loop gain and phase specifications must be met. The oscillation specification of this analog signal is easily interfered. Even if ground guard traces are added, it may not be possible to completely isolate the interference. Moreover, if it is too far away, the noise on the ground plane will also affect the positive feedback oscillation circuit. Therefore, the distance between the crystal oscillator and the chip must be as close as possible.

It is true that there are many conflicts between high-speed wiring and EMI requirements. But the basic principle is that the resistors, capacitors or ferrite beads added due to EMI cannot cause some electrical characteristics of the signal to not meet the specifications. Therefore, first use the techniques of arranging routing and PCB stacking to solve or reduce EMI problems, such as routing high-speed signals on the inner layer. Only then use resistors, capacitors or ferrite beads to reduce damage to the signal.

How to solve the contradiction between manual routing and automatic routing of high-speed signals?

Most of the current powerful routing software’s automatic routing tools have set constraints to control the winding method and the number of vias. The winding engine capabilities and constraint setting items of various EDA companies are sometimes very different. For example, whether there are enough constraints to control the winding method of the serpentine, whether the routing spacing of the differential pair can be controlled, etc. This will affect whether the routing method generated by automatic routing can meet the designer’s ideas. In addition, the difficulty of manually adjusting the routing is also related to the ability of the winding engine. For example, the pushing ability of the routing, the pushing ability of the via, and even the pushing ability of the routing to the copper plating, etc. Therefore, choosing a routing tool with a strong winding engine capability is the solution.

About test coupon.

The test coupon is used to measure the characteristic impedance of the produced PCB board with TDR (Time Domain Reflectometer) to see if it meets the design requirements. Generally, the impedance to be controlled is single line and differential pair. Therefore, the trace width and line spacing (when there is a differential pair) on the test coupon should be the same as the line to be controlled. The location of the ground point during measurement is important. In order to reduce the inductance of the ground lead, the grounding point of the TDR probe is usually very close to the probe tip, so the distance and method between the point where the signal is measured on the test coupon and the ground point should be consistent with the probe used.

In high-speed PCB design, the blank area of the signal layer can be copper-plated, and how should the copper of multiple signal layers be distributed in grounding and power supply?

Generally, the copper plating in the blank area is mostly grounded. However, when plating copper next to high-speed signal lines, pay attention to the distance between the copper plating and the signal line, because the copper plating will reduce the characteristic impedance of the trace a little. Also be careful not to affect the characteristic impedance of other layers, such as in the dual strip line structure.

Can the signal line on the power plane be calculated using the microstrip line model? Can the signal between the power and ground planes be calculated using the stripline model?

Yes, both the power plane and the ground plane must be considered as reference planes when calculating the characteristic impedance. For example, a four-layer board: top layer-power layer-ground layer-bottom layer. At this time, the model of the characteristic impedance of the top layer routing is a microstrip line model with the power plane as the reference plane.

Can the automatic generation of test points on high-density printed circuit boards by software generally meet the test requirements of mass production?

Whether the test points automatically generated by general software meet the test requirements depends on whether the specifications for adding test points meet the requirements of the test equipment. In addition, if the routing is too dense and the specifications for adding test points are strict, it may not be possible to automatically add test points to each line. Of course, the places to be tested need to be filled manually.

Will adding test points affect the quality of high-speed signals?

As for whether it will affect the signal quality, it depends on the way of adding test points and how fast the signal is. Basically, the additional test point (without using the existing via or DIP pin as the test point) may be added to the line or a short line may be pulled out from the line. The former is equivalent to adding a very small capacitor to the line, and the latter is an additional branch. Both situations will have some impact on the high-speed signal, and the degree of impact is related to the frequency speed of the signal and the edge rate of the signal. The magnitude of the impact can be known through simulation. In principle, the smaller the test point, the better (of course, it must meet the requirements of the test equipment) and the shorter the branch, the better.

How should the ground wires between the boards of a system be connected when several PCBs are connected to each other?

When the signals or power supplies between the PCB boards are in operation, for example, when the power supply or signal from board A is sent to board B, there will be an equal amount of current flowing back from the ground layer to board A (this is Kirchoff current law). The current on the ground layer will flow back to the impedance. Therefore, at each interface where the power supply or signal is connected to each other, the number of pins allocated to the ground layer should not be too small to reduce the impedance, so as to reduce the noise on the ground layer. In addition, the entire current loop can be analyzed, especially the part with larger current, and the connection method of the ground layer or ground wire can be adjusted to control the flow of current (for example, create low impedance at a certain place to let most of the current flow through this place) to reduce the impact on other more sensitive signals.

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‌What is a high frequency pcb communication circuits

Definition of high frequency pcb communication circuits

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How to choose high-frequency circuit board high-speed board

Composition and key components of high frequency pcb communication circuits

Application of high frequency pcb communication circuits

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