Posts Tagged ‘pcb design’

Thursday, August 22nd, 2024

PCB design is an indispensable part of modern electronic product development. An efficient and reliable PCB design can ensure the normal operation of the circuit and meet the performance and manufacturability requirements of the product.

PCB design (Printed Circuit Board Design) refers to the design of circuit boards using electronic design automation software (EDA), designing the layout and circuit connections of printed circuit boards (PCBs). Circuit boards are an important part of electronic products. They can connect electronic components together and transmit signals through wires.

Is PCB design hard to learn?

PCB design is not difficult to learn. The key lies in mastering the relevant basic knowledge and practical experience.

PCB design mainly involves electronic circuit knowledge and software operation skills. For people with electronic circuit foundation, it is relatively easy to learn the use of PCB design software. It is important that learners should use their spare time to learn and practice at the same time. They can assist in learning by watching video tutorials. These resources can help understand the basic concepts and skills of circuit design and software operation.

In addition, the difficulty of PCB design lies mainly in the design of wiring rules, which is the most complex and critical part of PCB design. Beginners should pay attention to the design of conventional constraint rules, such as the size of vias, line width and line spacing, etc., which need to be mastered through practical operation and practice. Just reading materials is not enough. Practical operation and practice are the key to improving PCB design capabilities.

In general, although PCB design involves certain technical difficulties, it can be gradually mastered through systematic learning and practice.

What should I learn before PCB design?

Before PCB design, you need to learn the following key knowledge and skills:

1. Basic knowledge reserve: First of all, you need to understand various electronic components, such as resistors, capacitors, inductors, diodes, triodes, integrated circuits, etc. You also need to be familiar with common circuit topologies, such as amplifier circuits, filter circuits, oscillation circuits, and their functions and representation methods in circuits.

2. PCB design software: Be proficient in at least one PCB design software for schematic design, component layout, wiring, and generation of PCB production files, such as Altium Designer, EAGLE, PADS, OrCAD, etc.

3. Circuit board manufacturing process: Understand the manufacturing process of PCB circuit boards, including substrate material selection, circuit pattern transfer, etching, drilling, welding, assembly, etc.

4. Component packaging: Familiar with the packaging types and sizes of various components, such as DIP, SOP, QFP, BGA, etc., as well as their characteristics and usage scenarios.

5. Basic terms and concepts: Master some basic PCB terms, such as microstrip, stripline, differential line, via, solder mask, silk screen, structural diagram, etc.

6. Circuit function and signal flow: Understand the function and signal flow of the circuit, and be able to distinguish between digital circuits and analog circuits, as well as places with large and small currents.

By mastering the above knowledge and skills, you can better design and layout circuits, improve the performance and reliability of circuit boards,

Which software is used for PCB design?

1. Altium Designer is a powerful PCB design software that provides a wealth of tools and libraries to quickly create complex circuit board designs. This software has an intuitive interface and powerful simulation functions to help designers quickly verify the correctness of the design. It also supports multiple design file formats, which is convenient for collaboration with other design tools.

2. Cadence Allegro is a comprehensive circuit board design software with powerful layout and routing tools, as well as multiple simulation and verification tools to ensure the correctness of the design. It also supports multiple design file formats for team collaboration.

3. Mentor Graphics DesignX is also a powerful PCB design software that provides a variety of tools and libraries to help designers quickly create complex circuit board designs. It also has an intuitive interface and powerful simulation functions, and supports multiple design file formats.

4. PADS is a professional circuit board design software with powerful layout, routing, simulation and verification functions, which can quickly complete complex PCB design work. It also supports multiple design file formats, which is convenient for collaboration with other design tools.

These software are all commonly used PCB design tools with powerful layout, routing, simulation and verification functions, which can help designers quickly complete complex PCB design work.

What is the basic rule of PCB design?

The basic rules of PCB design involve many aspects, including layout, routing, power and ground design, signal integrity, etc.

1. Layout design:

Follow the design principle of placing in a straight line along the signal flow direction to avoid the signal from circling back and forth to reduce the impact of direct signal coupling.

The filtering, protection and isolation devices of the interface circuit should be placed close to the interface to achieve effective protection, filtering and isolation effects.

For high-speed signals or high-current signals, multi-layer board design should be considered to control the signal loop area.

2. Wiring rules:

Control the length of the trace, especially for important signal lines, such as clock signals, the trace length should be shortened as much as possible to reduce unnecessary interference.

Avoid forming self-loop traces to reduce radiation interference.

Follow the principle of minimum ground loop, design the signal line and its loop to form the smallest possible loop area to reduce external radiation and external interference.

3. Power and ground design:

The power plane should be retracted a certain distance relative to its return ground plane to effectively suppress edge radiation problems.

Avoid overlapping of different power layers in space to reduce interference between different power supplies.

4. Drawing:

When drawing the board frame, a specific line width should be used to ensure that the error between the board frame size and the assembly size is within the allowable range.

Set a reasonable origin to ensure that the coordinates of the SMT original are within the first quadrant.

Set a prohibited area, especially prohibiting routing and placing components within a certain range around the mounting hole.

Following these basic rules can ensure the effectiveness and reliability of PCB design, while improving product performance and user experience.

How long does it take to design a PCB board?

It takes about 1-2 days to design a PCB board, and the specific time depends on multiple factors, including the number of layers of the PCB, design complexity, etc.

‌Number of layers and complexity‌: The more layers the PCB has, the more complicated the design process is, and more time and delicate work are required to ensure the correctness and performance of the circuit.

‌Design stage‌: PCB design includes multiple steps such as design layout, schematic drawing, and PCB design conversion.

The time to design a PCB board is a comprehensive estimate involving multiple stages and factors.

What is the proper PCB layout?

Proper PCB layout involves many aspects, including structural requirements, heat dissipation considerations, component spacing, routing rules, etc. ‌

‌Structural requirements‌: First, the PCB layout must meet the structural requirements, including the location arrangement of structural components such as power sockets and DVI interfaces.

‌Heat dissipation considerations‌: The distribution of heat sinks should be even to ensure good ventilation of the air path. Avoid heat sinks blocking the air path to avoid affecting the heat dissipation effect‌.

‌Component spacing‌: Capacitors, ICs, etc. should be kept away from thermal components to avoid being affected by heat.

‌Routing rules‌: The design of the current loop should consider the convenience of threading, and the lead hole spacing should not be too far or too close. The layout of input/output and AC/socket should meet the consistency of the length of the two lines, leaving a certain space margin, and pay attention to the position of the plug wire buckle and the convenience of plugging and unplugging‌.

‌Special component layout‌: For high-frequency components and components with high potential difference, the distance between them should be increased to avoid electrical interference and damage.

Wiring design parameters‌: including the line width of the copper trace, the minimum gap between the copper foil traces, the minimum distance between the copper foil traces and the edge of the PCB board, etc. ‌ .

In summary, the correct PCB layout is a process that comprehensively considers the structure, heat dissipation, component spacing, routing rules and wiring design parameters, aiming to optimize the performance and reliability of the circuit board.

Conclusion:

Designing a PCB board is a complex and meticulous process involving multiple steps and considerations. Systematically complete the design process of a PCB board. Each step requires careful operation and multiple checks to ensure the quality and reliability of the final product. ‌ BEST Technology’s PCB designers have many years of design experience and are far ahead in the industry design. We can meet any PCB design you need.

What is the glass transition temperature and Its Significance?

The glass transition temperature (Tg) refers to the temperature corresponding to the transition from the glass state to the high elastic state. The glass transition is an inherent property of amorphous polymer materials and a macroscopic manifestation of the transformation of the polymer motion form. It directly affects the performance and process performance of the material. Therefore, it has long been the main content of polymer physics research.

The glass transition temperature is of great significance to the application of polymers. Above this temperature, polymers show elasticity; below this temperature, polymers show brittleness. This characteristic must be considered when used as plastics, rubber, synthetic fibers, etc.

The glass transition temperature of mainstream FR-4 boards is approximately between 130-140℃. In the PCB manufacturing process, the temperature needs to be strictly controlled to avoid exceeding the glass transition temperature to ensure the quality of the product.

Is higher glass transition temperature better?

In PCB manufacturing, the higher the glass transition temperature (Tg), the better. ‌

The glass transition temperature is an important performance indicator of polymer materials, which determines the changes in the physical and chemical properties of the material at a specific temperature. When the temperature of the polymer is lower than its glass transition temperature, the material exhibits hard and brittle characteristics, similar to the glass state; when the temperature is higher than the glass transition temperature, the material becomes soft and exhibits elasticity similar to rubber or leather. This state change has a direct impact on the performance during PCB manufacturing and use.

1. ‌ Temperature deformation resistance ‌:

The higher the Tg value, the stronger the material’s temperature deformation resistance. This means that in a high temperature environment, such as during SMT welding, the PCB substrate is not easy to deform, thereby maintaining dimensional stability, which is crucial to ensure the reliability and long-term use of the circuit board.

2. ‌ Electrical performance and mechanical strength: ‌

The high or low Tg value directly affects the electrical performance and mechanical strength of the PCB. High Tg materials can maintain good physical and chemical stability at high temperatures, thereby maintaining the electrical properties and mechanical strength of the circuit board, which is crucial to improving the quality and reliability of the product.

3. Safety:

PCB materials with high Tg values are not easy to soften or melt at high temperatures, thereby improving the safety and durability of the circuit board and reducing the risk of short circuits or other damage caused by high temperatures.

In summary, choosing PCB materials with higher Tg values is one of the key factors to ensure that the circuit board maintains stable performance and safety in complex manufacturing and use environments.

What is glass transition temperature vs melting temperature?

In PCB manufacturing, glass transition temperature and melting temperature are two different physical properties that describe the state changes of materials under different conditions. ‌

The glass transition temperature (Tg) mainly involves amorphous materials or amorphous regions in partially crystalline materials. At this temperature, the physical state of the material changes from glass to highly elastic.

The melting temperature (melting point) mainly involves the melting process of crystalline materials. For crystalline polymers, the melting point marks the temperature at which the molecular chain begins to move, that is, the material changes from solid to liquid. The melting point is related to the crystallinity and lattice structure of the material and is a physical property unique to crystalline materials.

In short, the glass transition temperature mainly affects the amorphous region in amorphous or partially crystalline materials, while the melting temperature mainly affects crystalline materials and involves the melting process of the entire crystal. These two temperatures reflect the different physical state changes of different materials when heated.

How do you determine the glass transition temperature?

Expansion method, thermomechanical method, differential scanning calorimetry (DSC), DTA method, dynamic mechanical property analysis (DMA) method, nuclear magnetic resonance method (NMR).

Differential scanning calorimetry (DSC) is the most traditional and commonly used measurement method. It measures the relationship between the power difference (heat flow rate) and temperature between the sample and the reference material, and then obtains the glass transition temperature of the material;

Dynamic mechanical analysis (DMA) is the most sensitive method. It measures the sinusoidal alternating stress of constant amplitude applied to the sample, observes the change of strain with temperature or time, and calculates the mechanical parameters to characterize the elastomer;

Thermomechanical analysis (TMA): Use a probe with good sensitivity to measure the expansion coefficient of the material, and measure the glass transition temperature of the material based on this change.

What is the difference between TM and Tg?

In the PCB industry, TM and Tg are two different parameters, representing two different physical properties.

Tm: melting point; m is the melting point of crystalline polymers, that is, the temperature at which crystalline polymers melt. It is the highest use temperature of crystalline polymers when used in plastics and fibers, and it is also their heat resistance temperature and the lowest temperature for molding processing.

What is the Tg of polyurethane?

The glass transition temperature (Tg) of polyurethane is not a fixed value, but a physical quantity determined by the type of resin.

‌There are many types of polyurethane, including polyether, polyester, polyimide, polyurea, etc. Each type of polyurethane has its own specific glass transition temperature.

Shape memory polyurethane has a small volume expansion rate at temperatures below Tg, but increases at temperatures above Tg, which shows the characteristics of its glass transition temperature. Therefore, to determine the glass transition temperature of a specific polyurethane, its specific chemical structure and application field need to be considered.

What is Tg for epoxy?

The Tg value of PCB epoxy resin is usually between 130℃ and 170℃. ‌

The Tg value (glass transition temperature) of PCB (printed circuit board) epoxy resin is an important performance indicator, which reflects the change in the physical state of the material when heated. According to different application requirements, the Tg value of PCB epoxy resin can be divided into several grades:

‌TG130‌: The temperature resistance of this type of board is about 140℃. Common Tg value boards of this type are Shengyi S1141 and Jiantao KB-6164F.

TG150: A medium Tg board with a temperature range of 150°C to 170°C. Common boards with this type of Tg include Shengyi S1141 150 and Jiantao KB-6165F.

TG170: A high Tg board with a temperature range of over 170°C. Common boards with this type of Tg include Shengyi S1170 and Jiantao KB-6167F.

Selecting the right Tg value is critical to ensuring the performance and reliability of the PCB. Although boards with high Tg values are relatively expensive, their superior temperature resistance is indispensable in applications that require higher temperatures, such as aerospace. In addition to Tg values, other factors should be considered when selecting PCB boards, such as thermal decomposition temperature (Td), which is another important indicator for evaluating the stability of boards at high temperatures.

Conclusion:

High Tg represents high heat resistance. Electronic products represented by computers are developing towards high functionality and high multi-layer, which requires higher heat resistance of PCB substrate materials as an important guarantee. BEST Technology focuses on manufacturing high-performance PCB circuit boards and is far ahead in the industry. It has professional production equipment and 18 years of design experience, and has high quality requirements for products.

PCB Line Width and Flow Current Comparison Table Chart

PCB Line Width and Flow Current Comparison Table Chart
Line width (mm)	Current (A)	Line width (mm)	Current (A)	Line width (mm)	Current (A)
0.15	0.2	0.15	0.5	0.15	0.7
0.2	0.55	0.2	0.7	0.2	0.9
0.3	0.8	0.3	1.1	0.3	1.3
0.4	1.1	0.1	1.35	0.4	1.7
0.5	1.35	0.5	1.7	0.5	2.0
0.6	1.6	0.6	1.9	0.6	2.3
0.8	2.0	0.8	2.4	0.8	2.8
1.0	2.3	1.0	2.6	1.0	3.2
1.2	2.7	1.2	3.0	1.2	3.6
1.5	3.2	1.5	3.5	1.5	4.2
2.0	4.0	2.0	4.3	2.0	5.1
2.5	4.5	2.5	5.1	2.5	6.0
Copper thickness 1OZ (0.035mm)		Copper thickness 1.5OZ (0.05mm)		Copper thickness 2OZ (0.7mm)

From the chart as above:

35um copper thickness and 0.4mm line width, the current is 1.1A;

50um copper thickness and 0.4mm line width, the current is 1.35A;

70um copper thickness and 0.4mm line width, the current is 1.7A.

Best Technology PCB Line Width and Flow Current Calculator

When using copper foil as a conductor for large currents, the width of the copper foil should be selected by reducing the current-carrying capacity values from the reference table by 50%. However, there are other methods to address this. In some power circuits, due to PCB constraints, the current-carrying paths are designed as long pads, and solder is added on top of them to form a thick current path. Besides adding tin to the copper foil to increase the current capacity, you can also consider using multiple PCB layers to increase the current. For instance, placing the same circuit on both the top and bottom layers or using short jumper wires can also help increase the current capacity.

How Wide Should the Trace be If Current is 1A?

1. Due to the limited thickness of the copper foil on the copper-clad board, the current-carrying capacity of the copper foil needs to be considered for strip-shaped copper foil that needs to carry a large current. Taking the typical thickness of 0.03mm as an example, if the copper foil is used as a strip-shaped conductor with a width of W (mm) and a length of L (mm), its resistance is 0.0005 L / W ohms. Additionally, the current-carrying capacity of the copper foil is related to the types of components installed on the PCB, their quantity, and the heat dissipation conditions. Under safe conditions, the current-carrying capacity can generally be calculated using the empirical formula: 0.15 W (A).

2. The calculation method is as follows: First, calculate the cross-sectional area of the track. Most PCBs have a copper foil thickness of 35μm (if unsure, you can ask the PCB manufacturer). Multiply this by the trace width to get the cross-sectional area, making sure to convert to square millimeters. There’s an empirical value for current density, which is 15-25 amperes per square millimeter. Multiply this by the cross-sectional area to get the current capacity.

3. I = K T^0.44 A^0.75, where K is a correction factor (0.024 for internal copper traces, 0.048 for external copper traces), T is the maximum temperature rise in degrees Celsius (copper’s melting point is 1060°C), A is the copper cross-sectional area in square mils (not square millimeters, so be mindful of the conversion), and I is the allowable maximum current in amperes (amps). Typically, 10 mil = 0.010 inches = 0.254 mm, which can carry 1A. Therefore, 250 mil = 6.35 mm can carry 8.3A.

4. The calculation of PCB current-carrying capacity has long lacked authoritative technical methods and formulas. Experienced CAD engineers can make accurate judgments based on personal experience. However, for CAD novices, this can be quite a challenge.

5. PCB current-carrying capacity depends on the following factors: trace width, trace thickness (copper foil thickness), and allowable temperature rise. As we all know, the wider the PCB trace, the greater the current-carrying capacity. Under the same conditions, a 10mil trace can carry 1A, but can a 50mil trace carry 5A? The answer is, of course, no.

Current-Carrying Capacity of External PCB Traces (1mil = 0.0254mm)

Line length – current carrying data chart (unit: A)

Line width (mil)	Line length 5cm	Line length 10cm	Line length 15cm	Line length 20cm	Line length 25cm	Line length 30cm	Line length 35cm	Line length 40cm
4	0.403	0.201.	0.134	0.101	0.081	0.067	0.058	0.050
6	0.604	0.302	0.201	0.151	0.121	0.101	0.086	0.075
8	0.753	0.403	0.268	0.201	0.161	0.134	0.115	0.101
10	0.886	0.503	0.336	0.252	0.201	0.168	0.144	0.126
12	1.011	0.604	0.403	0.302	0.242	0.201	0.173	0.151
16	1.245	0.805	0.537	0.403	0.322	0.268	0.230	0.201
20	1.464	1.007	0.671	0.503	0.403	0.336	0.288	0.252
30	1.964	1.510	1.007	0.755	0.604	0.503	0.431	0.378
40	2.419	2.013	1.342	1.007	0.805	0.671	0.575	0.501
50	2.844	2.517	1.678	1.258	1.007	0.839	0.719	0.629
60	3.246	3.020	2.013	1.510	1.208	1.007	0.862	0.755
80	3.999	3.999	2.684	2.013	1.611	1.342	1.150	1.007
100	4.701	4.701	3.356	2.517	2.013	1.678	1.438	1.258
120	5.365	5.365	4.027	3.020	2.413	2.013	1.726	1.510
160	6.610	6.610	5.369	4.027	3.221	2.684	2.301	2.013
200	7.770	7.770	6.711	5.033	4.027	3.355	2.876	2.517
240	8.868	8.868	8.053	6.040	4.832	4.027	3.451	3.020
280	9.917	9.917	9.395	7.047	5.637	4.698	4.027	3.523
320	10.925	10.925	10.738	8.053	6.443	5.369	4.602	4.027
360	11.899	11.899	11.899	9.060	7.248	6.040	5.177	4.530
400	12.844	12.844	12.844	10.067	8.053	6.711	5.752	5.033

For low-frequency, low-current PCB designs, the general trace width is around 10 mil, and for more compact designs, 6 mil may be used. The key factor in determining PCB trace width is the current: higher currents require wider traces, while lower currents can use narrower traces. The operating frequency also plays a role in determining the width.

Ideally, the width of the PCB power trace should be at least 40 mil, with a minimum of 25 mil when conditions allow. Always opt for the widest trace possible to accommodate the current.
Consider the actual current flow. Typically, a 10 mil trace can carry a maximum of 1A, so adjust the width according to the current requirements.
The ground trace should be wider than the V+ trace and should surround the V+ trace to reduce interference and power ripple.
When converted to millimeters, the positive power trace should be no less than 0.6mm wide, while the negative power trace should be wider than the positive trace and surround it.

How Are Multilayer Boards Constructed?

The multi-layer board is composed of several single sided PCB for the outer layer and some double-sided PCBs for the inner layer.

l Single-Sided Boards

In the most basic PCB design, components are placed on one side of the board, and the wiring is on the other. This is called a single-sided board. Due to strict routing limitations (since traces cannot cross each other), single-sided boards are mostly used in simpler circuits.

l Double-Sided Boards

Double-sided boards have wiring on both sides. To connect the circuits on both sides, vias (small holes filled or coated with metal) are used. The larger area and ability to route traces through both sides make double-sided boards more suitable for complex circuits compared to single-sided boards.

l Multilayer Boards

To increase routing space, multilayer boards are created by combining multiple layers of single-sided or double-sided boards. For example, a four-layer or six-layer PCB might consist of a double-sided board as the core with single-sided boards on either side, all bonded together. Multilayer boards allow more complex designs, and while most modern PCBs use between 4 to 8 layers, designs with up to 100 layers are possible for advanced computing needs, though they are increasingly rare due to advances in other technologies.

The number of layers doesn’t always indicate the number of wiring layers—some layers may be added purely to adjust board thickness. Most motherboard designs consist of 4 to 8 layers, and while extremely complex multilayer boards were once used in supercomputers, they are now often replaced by clusters of standard machines.

Trace Width and Copper Pour Guidelines

When designing PCBs, a general rule is to use thicker traces for high-current areas (e.g., 50 mil or more) and thinner traces for low-current signals (e.g., 10 mil). In some electromechanical control systems, the instantaneous current through a trace can exceed 100A, in which case thin traces would fail.

An empirical rule of thumb is that 10A can safely pass through 1 square millimeter of trace cross-section. If the trace is too thin, it may burn out under high current. This phenomenon follows the energy equation: Q = I^2*t. For example, a trace designed for 10A can likely handle a sudden current spike of 100A for microseconds, but beyond that, other factors like stray inductance in the trace could generate strong counter-electromotive forces, potentially damaging other components. Longer and thinner traces have higher stray inductance, so their length must also be considered.

Copper Pouring on Vias and Pads

Most PCB design software offers options for how to connect vias or pads to copper planes, such as direct pour, orthogonal spokes, or 45-degree angled spokes. While many designers select based on aesthetics, these choices affect both current capacity and heat dissipation.

l Direct Pour: This method provides the strongest current-carrying capacity for pads or vias, making it ideal for high-power circuits. However, direct pours also enhance heat conduction, which, while beneficial for cooling components, can complicate soldering by rapidly dissipating heat, requiring higher soldering temperatures and larger soldering irons, which may reduce production efficiency.

l Orthogonal and 45-Degree Spokes: These methods reduce the contact area between the pad or via and the copper, slowing heat dissipation and making soldering easier. For low-power signal traces, orthogonal or 45-degree spokes are recommended, while direct pour is necessary for pads carrying high currents. The choice between orthogonal and 45-degree spokes is mainly aesthetic.

What is a High Speed Circuit PCB?

High-speed PCB is a circuit board that can support signal transmission. High-speed signals usually refer to signals with frequencies higher than 50MHz, such as high-speed digital signals, high-speed analog signals, etc. These fast transitions can introduce challenges like signal reflections, electromagnetic interference (EMI), and crosstalk, which can disrupt performance if not properly managed.

Additionally, these signals will be affected by board materials, layout, wiring and other factors during transmission. Therefore, a specially designed circuit board is required to ensure the integrity and reliability of the signal. Here is a 4 layers high speed PCB for Iradar device with 50ohm single-ended impedance control.

Features of High-Speed PCB

High frequency

Low permittivity and low loss factor

Multilayer design

Strict impedance control

High-precision manufacturing

Low noise characteristic

High density circuit layout (micro-vias)

High performance

What is Considered High-Speed PCB Design?

High-speed PCB design focuses on managing the complexities that come with high-frequency signals and fast switching. Key considerations include:

– Signal Integrity: Ensuring signals travel without distortion or loss.

– Power Management: Distributing power effectively to minimize noise and voltage drops.

– Heat Handling: Managing heat from high-speed components to prevent overheating.

– Impedance Matching: Keeping impedance consistent to reduce signal reflections and loss.

– Differential Pair Routing: Reducing EMI and crosstalk by routing complementary signal pairs together.

This type of high speed pcb design requires a solid understanding of electromagnetic principles, advanced simulation tools, and precise manufacturing techniques. For those new to high-speed PCB design, Best Technology offers expert guidance and solutions.

What’s the Best Material for High-Speed PCB Design?

Choosing the right material for high speed pcb is vital for maintaining signal integrity and achieving optimal performance. The material impacts the board’s dielectric constant (Dk), loss tangent, and overall signal quality. Common materials include:

– FR4: Widely used but not ideal for very high frequencies due to higher loss tangent.

– Rogers (RO4000 series): Preferred for high-speed designs thanks to its low dielectric constant and loss tangent.

– Teflon: Excellent for high-frequency applications but more expensive and harder to process.

Selecting the appropriate material ensures the PCB can handle high-speed signals without compromising performance.

Where is the High-Speed PCB Commonly Used in?

High-speed circuit boards are widely used in signal transmission applications, the typical fields are including:

1. Communication equipment – such as 5G base stations, optical fiber communication equipment, etc.

2. Data center – like high-performance computing, storage servers, etc.

3. Consumer electronics in our daily life – high-end smartphones, tablets, gaming devices, etc.

4. Aerospace and military – high speed are always used in high-end devices. For example, radar, navigation systems and other equipment with high reliability requirements.

What is the 3H Rule in High Speed PCB Design?

The 3H rule is a guideline suggesting that signal traces should be spaced at least three times the height of the dielectric (3H) between the signal layer and the adjacent ground or reference layer. This helps minimize crosstalk and maintain signal integrity, particularly for high-speed digital signals with rise times of 1 ns or less. Key aspects include:

– Trace Spacing: Keeping traces apart by at least 3H reduces electromagnetic coupling and interference.

– Signal Integrity: Adequate spacing helps maintain clear signals in high-speed circuits.

– Effectiveness: This rule is especially beneficial for fast digital signals, reducing the risk of crosstalk and interference.

For instance, if the dielectric height between the signal layer and the reference layer is 0.2 mm, traces should be at least 0.6 mm apart to follow the 3H rule.

How to Design a High-Speed Board?

Designing a high-speed PCB involves several strategies to ensure effective signal transmission, power distribution, and minimal EMI. Here’s a step-by-step approach:

Component Placement and Layer Stack-Up

Place high-speed components to minimize signal paths and interference. Group related components to simplify routing. In addition, create a layer stack-up that supports controlled impedance and reduces signal loss. Use ground planes between layers for a return path for high-frequency currents.

Trace Routing and Impedance Control

Keep high-speed traces short and direct, avoiding right-angle bends. Use microstrip or stripline configurations for controlled impedance and minimal noise. For impedance control, calculate and ensure consistent impedance for traces. Use differential pair routing for high-speed signals to reduce EMI and crosstalk.

Power Distribution and EMI Mitigation

Use decoupling capacitors near high-speed components to filter noise and stabilize the power supply. Design a robust power distribution network to minimize impedance and ensure stable voltage. And employ proper grounding and shielding techniques. Route high-speed signals on inner layers between ground planes to reduce EMI and provide a consistent return path.

Simulation and Testing

Use signal integrity analysis tools like SI or PI to simulate the PCB layout, predicting signal behavior and identifying potential issues. Analyze aspects like eye diagrams to assess signal quality.

High-speed PCB design is a complex but rewarding endeavor that ensures your electronics perform efficiently in high-frequency environments. By understanding the fundamentals and applying the right techniques and materials, you can create robust, high-speed boards. Best Technology is here to assist you with expert advice and solutions for your high-speed PCB needs.

PICE card

[1]: Main chip: XCKU11P

[2]: 30A maximum current

[3]: Single pair differential line, 10G optical network

[4]: 14 layers PCB

If you need a custom industrial PCB design, please feel free to contact us.

Video decoder

[1]: Xlinx: XC7K325T, Hisilicon: HI3521DV100_VI

[2]: Single pair differential line, 10G optical network, memory of DDR4

[3]: 12 layers PCB

Why choose us?

We are a China based fabricator with over 17 years experience, what we provide not only including PCB design service, but also PCB fabricating, PCB duplicating and component sourcing and so on. Choose Best Technology you can enjoy:

Professional engineer evaluation

DFM analysis

One-time successully on prototyping

SI analysis of signal integrity

Electromagnetic compatibility (EMC) analysis

An ultra-high-speed camera rigid-flex circuit board

[1]: XCKU060 chip

[2]: 20A maximum current

[3]: Four DDR4 channels

[4]: 20 layers PCB

High Speed PCB Design Guidelines, PCB Camera Design Case

Camera PCB design considerations:

1. When the Camera adopts a connector: when the MIPI differential signal passes through the connector, the adjacent differential signal pairs must be isolated using GND pins; If it is not convenient to punch holes, the spacing between the difference pairs is at least 15mil.

2. If there is a reserved test point for the Camera connection seat, it should be close to the connection seat, and the Stub on the cable should be as short as possible.

3. Decoupling capacitors of AVDD/DOVDD/DVDD power supply need to be placed as close as possible to the Camera connection base.

4. The Camera layout needs to be far away from high-power radiation devices, such as GSM antennas.

5. CIF/MIPI and other signals, if there is a board to board connection through the connector, it is recommended that all signals be connected with a certain resistance value (between 2.2ohm and 10ohm, depending on the SI test), and reserve TVS devices.

Best Technology offers one-stop solutions for our values customers. And we provide free technical support for our customers. If you have similiar requirements, welcome to contact us at any time!

32X100G(QSFP28) large capacity convergence shunt

[1]: Marvell: 98CX8522

[2]: Single pair differential line, 25G optical network

[3]: 16 layers PCB

Differential Signal PCB Design, Fiber Optical SFP Module

How to design a SFP optical module PCB?

SFP optical module interface PCB design depends on many aspects, including interface signal processing, timing control, power management and so on.

1. Determine the interface standard: SFP optical module interface standards, such as SFP, SFP+, QSFP and so on, you need to choose the appropriate interface standard according to the specific needs.

2. Choose the chip solution: According to the interface standard, choose the appropriate chip solution, usually including constant voltage source, amplifier, comparator, clock generator, EEPROM, etc.

3. Signal processing: For receiving and sending signals, filtering, amplification and comparison are required to ensure signal quality and stability.

4. Timing control: The timing and frequency of the clock signal need to be accurately controlled to ensure the correctness and stability of data transmission.

5. Power management: SFP optical module interface requires multiple power supplies, including Vcc, VCC-TX, VCC-RX, etc. Reasonable power management is required to ensure the stability and reliability of the power supply.

6. PCB design: According to the above requirements, PCB design is carried out, considering signal isolation, layering layout, status separation, signal integrity and other factors.

Feel freely to send message us if you are interested in PCB design.

10G/100G large capacity convergence shunt

[1]: Marvell: 98DX8548

[2]: 21A maximum current

[3]: Single pair differential line, 10G and 25G optical networks

[4]: 10 layers PCB

Motherboard Network Adapter PCB Design Solution Example

What are the considerations before PCB design?

PCB design involves several steps and some considerations need to be noticed. If you are a designer, think about these points before starting the design.

Manufacturing: prototyping study or mass production.
What it will be used in?
What kind of production technology it will used?
Material?
How many layers you want?
Whether need to do impedance control?

Best Technology has more than 17 years in this industry, we have served for over 1200 customer all around the world. Our goal is to provide customer with best solutions and top notch quality products, and it is luckily that we did a good job. If you want to work with us or need a PCB manufacturer in Asia, contact us right now!

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