What problems can occur in the ceramic PCB etching process?

August 15th, 2024

Ceramic PCB etching is a process that removes copper from a ceramic PCB by chemical methods to leave only the required copper traces on the board. This allows the creation of conductive paths between the components on the ceramic PCB that make up the circuit. Etching is a key step in ceramic PCB manufacturing, which can make ceramic PCB manufacturing efficient and up to standard.

During the ceramic PCB etching process, the chemical etchant solution dissolves the unwanted copper on the ceramic PCB laminate, while the resist (usually a polymer film) protects the copper traces from being etched away. After the etching is completed, only the desired copper circuit pattern remains on the ceramic PCB.

What are the reasons for uneven etching?

The reasons for uneven etching mainly include insufficient etching solution concentration, ‌high or low temperature, ‌long or short time, ‌incomplete film stripping on the substrate surface, ‌residual film, ‌uneven thickness of copper plating on the board surface when copper is plated on the entire board, etc. ‌

Uneven etching is one of the problems often encountered in the ceramic PCB etching process, ‌and its reasons are diverse and complex. ‌First of all, the problem of etching solution is an important factor leading to uneven etching. ‌If the concentration of the etching solution is insufficient, or the temperature is too high or too low, or the etching time is too long or too short, uneven etching may occur. ‌These problems can be solved by adjusting the concentration of the etching solution, controlling the etching temperature within an appropriate range, and ensuring that the etching time is within a reasonable range.

In addition, improper surface treatment of the substrate is also one of the reasons for uneven etching. ‌If the film on the substrate surface is not completely removed, there is residual film, or the thickness of the copper plating layer on the board surface is uneven when the copper is plated on the entire board, the uniformity of etching will be affected. ‌Similarly, if the ink is stained on the transmission roller of the etching machine when the board surface is corrected or repaired with ink, uneven etching may also occur.

How to avoid uneven etching?

Optimize the design of the etching tank: ensure the uniform distribution of the etching solution in the etching tank, design a reasonable liquid flow path, and improve the fluidity and uniformity of the etching solution.

Control the etching time: Reasonably control the etching time, avoid too long or too short etching time, and ensure uniform etching.

Stabilize the concentration of etching solution: Regularly monitor and adjust the concentration of etching solution to ensure the chemical composition of etching solution is stable.

How does the residue problem affect the etching quality?

Impact on etching uniformity: The presence of residues and impurities may have a serious impact on the success of the etching process, especially at the micro-nano scale, these residues and impurities may affect the uniformity of etching, resulting in a decrease in etching quality. ‌

Affect the uniformity and stability of etching solution: Residues and impurities may affect the uniformity and stability of etching solution, thereby affecting the quality of etching process. Factors such as etching solution concentration, pressure strength, temperature, speed and environment are all key factors affecting etching quality, and the presence of residues may interfere with the normal function of these factors, resulting in a decrease in etching quality. ‌

Affect the etching performance and quality of metal materials: The type and microstructure of metal materials have a significant impact on the etching process and quality. Alloy materials containing different elements will form micro-corrosion cells during the corrosion process, affecting the dissolution rate and uniformity of the metal corrosion process. The presence of residues may aggravate this effect, resulting in a decrease in etching quality. ‌

Requires additional cleaning and processing steps: In order to remove the residue, additional cleaning and processing steps may be required, which may increase production costs and time. ‌In addition, if the residue is difficult to remove or detect, it may also affect the quality and performance of the final product.

How to avoid the problem of residue?

Use pure etching solution: Select high-purity etching solution to ensure the purity and chemical activity of the etching solution.

Increase cleaning steps: Use a multi-step cleaning process to completely remove the etching solution and etching products to ensure that the surface is clean and residue-free.

Optimize process control: Strictly control parameters such as temperature, time, and concentration during the etching process to ensure stable etching effects.

What problems will over-etching cause?

Over-etching of ceramic PCBs will cause a series of problems, including excessive circuit etching, local corrosion, galvanic corrosion, etc.

Excessive circuit etching: When the circuit design is too detailed and the copper foil used is thick, it may cause excessive circuit etching, resulting in abnormal copper foil peeling strength, thus affecting the normal function of the circuit.

Local corrosion: includes filiform corrosion, crevice corrosion, and pitting corrosion. These types of corrosion are usually caused by chemical reactions between oxygen, moisture in the air and copper, or by corrosion in these crevices due to residual materials, hardware, or areas under components on the PCB.

Galvanic corrosion: When two different metals are coupled in a corrosive electrolyte, galvanic corrosion, also known as bimetallic corrosion, occurs.

In summary, excessive etching of ceramic PCBs may not only cause abnormal circuit function, but also cause a variety of corrosion problems, thus affecting the overall performance and life of the circuit board.

How to avoid excessive etching?

Reasonably control the etching time: According to the specific process requirements, reasonably control the etching time to ensure that the etching depth is moderate.

Adjust the etching solution concentration: According to the etching requirements, adjust the etching solution concentration to control the etching rate.

Optimize process parameters: During the etching process, strictly control process parameters such as temperature and pressure to avoid excessive etching.

How does graphic distortion affect the etching effect?

The main causes of graphic distortion include poor photoresist graphics, uneven distribution of etching solution, and improper etching process control.

Poor photoresist pattern: During the photolithography process, the photoresist pattern is unclear and uneven, which will cause the circuit pattern to be distorted after etching.

Uneven distribution of etching liquid: The uneven distribution of etching liquid in the etching tank will lead to different etching rates in different areas, resulting in inconsistent line width and shape, and pattern distortion.

Improper control of etching process: Improper control of process parameters such as temperature, time, and concentration during etching will lead to unstable etching rate and pattern distortion.

How to avoid image distortion?

Improve the quality of photoresist patterns: Use high-quality photoresist to ensure clear and uniform photolithography patterns and improve pattern accuracy.

Optimize etching tank design: Design a reasonable etching tank to ensure uniform distribution of etching liquid in the tank and reduce pattern distortion.

Strictly control process parameters: During the etching process, strictly control process parameters such as temperature, time, and concentration to reduce pattern distortion.

There are many common problems in the etching process of ceramic PCBs. These problems can be effectively solved by reasonably controlling the etching time, adjusting the etching liquid concentration, and using high-precision equipment. As a professional ceramic circuit board manufacturer, BEST Technology has 18 years of experience in ceramic PCB production. It can provide high-quality products and comprehensive technical support to ensure the success of the project and the reliable operation of the equipment.

Posted in best pcb, bestpcb, Ceramic PCB | No Comments »

How to Make SMT? What is SMT Process?

August 15th, 2024

What is the SMT?

Surface Mount Technology (SMT) is a production technique used to attach electronic components directly onto the surface of a printed circuit board (PCB). This method enables automated manufacturing to handle most of the assembly process needed to create a functioning board. Components attached in this way are known as surface-mount devices (SMDs). Unlike traditional methods, SMT does not involve inserting components through holes in the board. Instead, components are soldered directly onto the surface using reflow soldering.

Originally known as Planar Mounting, SMT was pioneered by IBM in the 1960s for small-scale computer production, replacing the earlier Through-Hole Technology. However, SMT didn’t gain widespread use until 1986, when surface-mounted components achieved 10% market penetration. By 1990, SMDs had become a dominant feature in most high-tech circuit card assemblies (CCAs).

What is the process of SMT manufacturing?

The SMT manufacturing process can be divided into three main stages: solder paste printing, component placement, and reflow soldering. Due to the complexity of the process, each stage is further broken down as follows:

1. Component and PCB Preparation

This initial stage involves selecting surface-mount components (SMCs) and designing the PCB. The board typically features flat copper pads plated with silver, tin-lead, or gold, which are called solder pads. These pads do not have holes and are used to support the pins of components like chips and transistors.

Another crucial element is the stencil, which is aligned with the solder pads to define the placement of solder paste during the next stage. The PCB and all materials involved must be thoroughly inspected to ensure there are no defects before proceeding with production.

2. Solder Paste Printing

Solder paste printing is a critical phase in SMT production. A stencil and squeegee are used to apply solder paste at an angle of 45° to 60°. The solder paste itself is a combination of powdered metal solder and flux, which temporarily holds components in place and cleans the soldering surfaces of impurities.

The paste is applied to the solder pads, connecting the SMCs to the PCB once melted in the reflow oven. It’s essential that the correct amount of paste is applied to each pad, as improper application can prevent proper connections from forming during reflow.

3. Component Placement

In this stage, pick-and-place machines accurately position components on the PCB. The machines use vacuum or gripper nozzles to remove each component from its packaging and place it onto the board. These machines are fast and precise, capable of placing up to 80,000 components per hour.

Precision is key here, as any misplaced components could lead to costly rework once soldered.

4. Reflow Soldering

After components are placed, the PCB is moved into the reflow oven for soldering. The board passes through several temperature-controlled zones:

Preheat Zone

The temperature is gradually increased to between 140℃ and 160℃ at a rate of 1.0℃-2.0℃ per second to ensure the board and components heat evenly.

Soak Zone

The PCB is maintained at this temperature for 60 to 90 seconds to stabilize the heat across the entire board.

Reflow Zone

The temperature is then raised to 210℃-230℃ to melt the solder paste, bonding the components to the PCB. The molten solder’s surface tension keeps the components in place during this process.

Cooling Zone

In the final zone, the solder is rapidly cooled to solidify the connections and prevent any soldering defects.

For double-sided boards, this process may need to be repeated, either using solder paste or adhesive to secure components.

5. Cleaning and Inspection

Once the soldering process is complete, the PCB is cleaned and inspected for any defects. This is done using magnifying lenses, Automated Optical Inspection (AOI), flying probe testers, X-ray inspection, and other tools to ensure accuracy. Any flaws are repaired before the finished product is packaged and stored.

What are the basics of SMT?

SMT simplifies assembly by reducing the need for drilled holes and using smaller components. Unlike traditional through-hole components, SMT parts are placed on the surface of the PCB, making the design more compact.

The basic elements of SMT include:

PCBs: The base for components, designed with specific pads for each part.
Solder Paste: A mixture of metal solder particles and flux, used to create a bond between components and the board.
SMT Components: Small electronic parts, such as resistors, capacitors, and ICs, that attach to the PCB.

The transition from through-hole technology to SMT has improved manufacturing speed and performance in electronics.

How do I prepare for SMT?

As the core step of electronic product manufacturing, PCBA’s preparation before assembly directly affects the quality and reliability of the final product. The following is a detailed analysis from multiple dimensions:

1. Component inspection

Before assembly, all electronic components must undergo strict screening and inspection. This includes checking that the component type, package, number of pins, etc. are consistent with the BOM (Bill of Materials), as well as performing the necessary electrical performance tests.

2. Take ESD measures

Static damage to electronic components is invisible, but the consequences are serious. Therefore, when distributing materials and testing IQC, warehouse personnel should wear anti-static gloves, reliably ground the instrument, and lay anti-static rubber MATS on the work surface. During the assembly process, the operator should also wear anti-static clothes, anti-static bracelets and other protective equipment to ensure that the workbench and equipment are well grounded.

3. Cleanliness requirements

The work workshop and workbench must be kept clean to prevent contaminants such as dust and impurities from entering the circuit board, affecting the accuracy and quality of the patch. Clean the work surface and workshop floor regularly. Smoking, eating and drinking are strictly prohibited in the work area.

4. Temperature and humidity control

Appropriate temperature and humidity should be maintained in the workshop to reduce static electricity generation and the impact on electronic components. It is usually recommended that the temperature be controlled at 23±3^oC and the humidity be controlled at 45% to 70%RH. This environment helps to ensure the quality of welding and the stability of electronic components.

5. PCB appearance check

Before assembly, the PCB board should be visually inspected to confirm whether it is complete, whether the surface coated solder resistance layer is intact, and whether there are obvious short circuits and defects. Use a multimeter to check whether there is a short circuit between the power supply and the ground terminal on the printed board, and ensure that the printed board is fine.

6. Check the software and hardware

When the PCBA needs to be upgraded, the motherboards produced in different time periods should not be mixed together to avoid mixing problems. Before assembly, check whether the final use of the software is in accordance with customer requirements to ensure that the software and hardware are compatible and correct.

7. Welding process selection

According to the layout of the circuit board and the characteristics of the components, select the appropriate welding process (such as wave soldering, reflow welding, hot blast furnace welding, etc.). Each welding method has specific requirements for the placement, orientation and spacing of components that need to be planned in advance.

8. Manually prepare the post-welding plug-in components

For some components that cannot be automatically welded (such as large connectors, heat sinks, etc.), manual plug-in assembly is required. This requires the operator to have a wealth of experience and skilled skills to ensure the accuracy and robustness of the plug-in.

9. Perform ESD operations

During operation, use an ESD workbench and an ESD container to hold components and semi-finished products. All welding equipment should be grounded, the electric soldering iron must be anti-static type, and tested before use.

10 Cleaning and protective treatment

After the assembly is complete, the product needs to be cleaned to remove the residue and contaminants generated during the welding process. At the same time, appropriate protective treatment of the product, such as spraying three anti-paint, etc., to improve the product’s moisture, dust and corrosion resistance.

Which solder paste is used in SMT?

The type of solder paste used in SMT assembly process depends on several factors, such as the materials of the components and the PCB, as well as the operating conditions of the finished product. Generally, there are mainly include high temperature solder paste, ‌ medium temperature solder paste and low temperature solder paste. ‌

High temperature solder pastes are commonly used in applications where higher temperatures are required for welding. ‌ has a higher melting point and ‌ is suitable for welding electronic components with specific temperature requirements. ‌
Medium temperature solder paste and low temperature solder paste are suitable for medium and low temperature welding respectively, ‌ select the appropriate solder paste type according to the specific welding needs. ‌

In addition, ‌ solder paste can also be classified according to the flux activity level, ‌ including “R” (‌ inactive) ‌, ‌ “RMA” class (‌ moderate activity) ‌, ‌ “RA” class (‌ completely reactive) ‌ and “SRA” class ‌ (‌ super activity). ‌ Different types of activity levels are suitable for different application scenarios, ‌ for example, ‌ “R” grade is usually used for welding aerospace, ‌ avionics products, ‌ and “RA” grade is suitable for consumer electronics products. ‌ This classification allows users to choose the right solder paste according to the specific application needs and cleaning process requirements. ‌

What temperature should a soldering iron be for SMT?

The right temperature for soldering in SMT can vary depending on the solder paste and components you’re using. Typically, the soldering iron should be set between 250°C and 300°C. Using a lower temperature might not properly melt the solder, while a higher temperature could damage components or the PCB.

Of course, different types of PCB requires different temperature. For example, ceramic PCBs has fragile surface, so a lower temperature is good.

What are the disadvantages of SMT?

Small volume (due to the limitation of components)
Fragility
High soldering requirements
Easily damaged or dropped
Challenging to inspect
Complex process and inspection
High equipment investment

How to solder SMT at home?

Soldering SMT components at home can be tricky, but with the right tools and techniques, it’s doable. Here’s a quick guide:

Tools: You’ll need a fine-tip soldering iron, tweezers, solder paste, and flux. You may also want a magnifying glass or microscope for better visibility.
Apply Solder Paste: Use a small amount of solder paste on the pads of the PCB where you want to place your components.
Place Components: With tweezers, carefully place the components onto the solder paste. Make sure they are properly aligned with the pads.
Reflow the Solder: If you have a reflow oven, you can use it to heat the board. Alternatively, a hot air rework station can also work.
Inspect: Once the solder has cooled, check the connections. If necessary, reheat or add more solder to fix any weak joints.

Best Technology is a one-stop PCB & PCB assembly manufacturer founded in 2006, with 5 assembly lines. If you have needs for PCB and PCBA fabrication, we can be your reliable supplier from prototypes to bulk production. In addition, we have SMT factory in Vietnam, if you don’t want to make smt in Shenzhen, then we can support you in Vietnam. Welcome to contact us if you have such PCB and PCBA projects.

Tags: PCBA, SMT, smt process
Posted in Uncategorized | No Comments »

What is a 3.3 k Resistor? 3.3 k ohm Resistor Color Code

August 15th, 2024

Resistors are a key part of any circuit board design. They help regulate current, manage voltage, and protect other components. One type that often appears in various projects is the 3.3 k ohm resistor. Whether you’re building a simple circuit or tackling a complex project, understanding the value and role of a 3.3 k ohm resistor can save you time and effort.

In this article, we’ll dive into what a 3.3 k ohm resistor is, how to identify it using the color code, and the differences between the 4-band, 5-band, and 6-band codes. Additionally, we’ll explain how to read an SMD resistor code, and explore the advantages of using this particular resistor in your projects.

What is a 3.3 k Ohm Resistor?

A 3.3 k ohm resistor is a fixed resistor that has a resistance value of 3,300 ohms. In electronic circuits, resistors limit current flow, divide voltages, and protect sensitive components from damage. The ‘k’ in the resistor’s name stands for kilo, meaning 1,000. Therefore, a 3.3 k ohm resistor has a resistance of 3,300 ohms. These resistors are widely used in both analog and digital circuits, making them a versatile choice for electronics enthusiasts.

3.3 k Ohm Resistor Color Code

The color code of a 3.3 k ohm resistor is a standardized way to easily identify the resistor’s value. You may notice a series of colored bands on the resistor’s body. Each of these bands represents a number, and when combined, they give you the resistance value.

For a 3.3 k ohm resistor, the color bands would typically be:

Orange (3)
Orange (3)
Red (×100 multiplier)
Gold or Silver (tolerance)

3.3 k Ohm Resistor Color Bands

Resistors typically have between 4 and 6 color bands. These bands convey different pieces of information such as resistance value, tolerance, and sometimes even temperature coefficient. The bands are read from left to right. Let’s break down a 4-band 3.3 k ohm resistor:

First Band: The first band indicates the first digit of the resistor value. In this case, orange represents the number 3.
Second Band: The second band represents the second digit, which is again 3.
Third Band: The third band is the multiplier, which in this case is red, meaning ×100.
Fourth Band: The fourth band is either gold (±5%) or silver (±10%) to represent tolerance.

How To Read the 3.3k Ohm Resistor Color Code?

Reading the 3.3k ohm resistor color code is straightforward once you understand how the color bands correspond to numerical values. Here is a resistor color band chart:

Color	Value	Multiplier	Tolerance
Black	0	×1	N/A
Brown	1	×10	±1%
Red	2	×100	±2%
Orange	3	×1,000	N/A
Yellow	4	×10,000	N/A
Green	5	×100,000	±0.5%
Blue	6	×1,000,000	±0.25%
Violet	7	×10,000,000	±0.1%
Gray	8	×100,000,000	±0.05%
White	9	×1,000,000,000	N/A
Gold	N/A	×0.1	±5%
Silver	N/A	×0.01	±10%
None	N/A	N/A	±20%

Step 1: Identify the number of bands

Resistors typically come with 4, 5, or 6 color bands. So, the first thing is to count how many color bands are on the resistor. For a 3.3k ohm resistor, the color bands are used to indicate the value of the resistance and the tolerance.

4-Band Resistor: Two significant digits, a multiplier, and a tolerance band.
5-Band Resistor: Three significant digits, a multiplier, and a tolerance band.
6-Band Resistor: Three significant digits, a multiplier, a tolerance band, and a temperature coefficient band.

Step 2: Read the digits according to the color band chart

For resistors with 4, 5, or 6 bands, the first two or three bands represent the significant digits of the resistance value. For a 3.3k ohm resistor, these digits are “3” and “3,” corresponding to the color orange.

For 5- and 6-Band Resistors, the first three color bands represent the significant digits. So, in a 5- or 6-band resistor, you would still have orange (3) and orange (3), with an additional third digit, typically black (0), in this case.

Step 3: Apply the Multiplier

The next band is the multiplier, which tells you what to multiply the significant digits by. For a 3.3k ohm resistor, the multiplier is red, indicating ×100.

For 4-Band Resistor, the third band is the multiplier. For 3.3k ohms, the third band is red, so you multiply the significant digits (33) by 100, giving you 3,300 ohms. And 5- and 6-Band Resistors, the fourth band is the multiplier. In this case, the multiplier is brown (×10), so the calculation would still result in 3,300 ohms.

Step 4: Check the tolerance

The final band in 4- and 5-band resistors represents the tolerance, which indicates how much the actual resistance value can vary from the stated value. For a 3.3k ohm resistor, this band could be either gold (±5%) or silver (±10%).

Gold Band: Indicates that the actual resistance can vary by ±5%.
Silver Band: Indicates that the actual resistance can vary by ±10%.

For example, if the tolerance is ±5%, the actual resistance of a 3.3k ohm resistor could be anywhere between 3,135 ohms and 3,465 ohms.

Step 5: Read the temperature coefficient (if present)

For 6-band resistors, the sixth band represents the temperature coefficient. This tells you how much the resistance changes with temperature, usually measured in parts per million per degree Celsius (ppm/°C). This is particularly important in high-precision circuits where temperature changes could significantly affect the performance of the resistor.

4-Band vs. 5-Band vs. 6-Band 3.3k Ohm Resistor Color Code

The number of bands on a resistor depends on its precision and tolerance. Here’s how the 3.3 k ohm resistor color code varies across different band systems:

Number of Bands	1^st Band	2^nd Band	3^rd Band	Multiplier	Tolerance	Temperature Coefficient
4-Band	Orange (3)	Orange (3)	Red (×100)	Red (×100)	Gold (±5%)	N/A
5-Band	Orange (3)	Orange (3)	Black (0)	Brown (×10)	Gold (±5%)	N/A
6-Band	Orange (3)	Orange (3)	Black (0)	Brown (×10)	Gold (±5%)	Brown (100 ppm/°C)

What is the Code for a 3.3 k SMD Resistor?

SMD (Surface Mount Device) resistors are small and lack the space for color bands. Instead, they use numbers to indicate their value. For a 3.3 k ohm SMD resistor, you will often see the code “332.” This code translates to 33 × 100, giving you 3,300 ohms.

What is the Color Code of a 333 k Resistor?

A 333 k ohm resistor has a resistance value of 333,000 ohms. The color code for this resistor would be:

Orange (3)
Orange (3)
Orange (×1,000 multiplier)
Gold or Silver (tolerance)

Advantages of a 3.3k Ohm Resistor

A 3.3k ohm resistor is commonly used in circuits requiring precise voltage regulation. Its resistance value is particularly suited for voltage dividers, where the ratio of the resistor values determines the output voltage. Here are some advantages of using 3.3k ohm resistor:

1. Precision in Voltage Regulation

2. Ideal for Current Limiting in LED Circuits

3. Commonly Used in Analog Signal Processing

4. Flexibility in Design and Configuration

5. Power Efficiency

6. Compatibility with Digital and Analog Devices

7. Stability and Durability

8. Cost-Effectiveness

What is the Tolerance of a 3.3k Ohm Resistor?

Tolerance refers to how much a resistor’s actual resistance value can vary from its labeled value. Common tolerance levels are ±5% (gold band) and ±10% (silver band). For example, a 3.3 k ohm resistor with a 5% tolerance could have a real resistance value between 3,135 ohms and 3,465 ohms.

Is k the Same as Ohm?

No, ‘k’ and ‘ohm’ are not the same. ‘Ohm’ (Ω) is the unit of resistance, while ‘k’ is a prefix meaning 1,000. So, when we say 3.3 k ohms, it means 3,300 ohms.

FAQs

1. How can I quickly identify a 3.3 k ohm resistor?

Look for the orange, orange, red color bands on the resistor body.

2. What is the role of a 3.3 k ohm resistor in a circuit?

It helps manage current, divide voltage, and protect other components from excess current.

3. Can I use a 3.3 k ohm resistor in high-frequency circuits?

Yes, its stable performance makes it suitable for both high and low-frequency circuits.

4. How do I check if a 3.3 k ohm resistor is working?

You can measure the resistance using a multimeter.

5. Why is a 3.3 k ohm resistor often used in audio circuits?

It offers a good balance of resistance, which is ideal for filtering and reducing noise in audio signals.

Tags: 3.3 k ohm Resistor Color Code, 3.3 k resistor
Posted in best pcb, bestpcb, FAQ | No Comments »

hdi printed circuit board,hdi pcb manufacturer

August 14th, 2024

What is hdi pcb?

HDI stands for High Density Interconnect, which refers to high-density interconnect technology. HDI circuit board is a high-end printed circuit board with very high circuit density and complexity, which can achieve high-speed signal transmission and reliability design. The main features of HDI circuit board are multi-layer circuit, thin plate, small aperture, dense wiring and fine circuit. It is widely used in mobile phones, computers, network communications, automotive electronics and other fields. Bestpcb is a professional HDI manufacturer with 18 years of HDI manufacturing experience.

What are the advantages of hdi pcb

Higher line density: HDI PCB can support more circuit tracks, arrange more electronic components in a limited space, and achieve high-density interconnection.
Smaller device spacing: The micro-hole technology of HDI PCB allows smaller spacing between components, which is suitable for compact design.
Improve signal integrity: The advanced stacking layer structure is adopted to provide better signal transmission quality and reduce signal interference.
Improve reliability: The manufacturing process of HDI PCB improves the mechanical strength of the board, making it more durable and suitable for demanding application environments.
Improve circuit integration: More line connections and component arrangements are achieved in a limited circuit board space to meet the needs of modern products that are thin and compact.
Enhance signal transmission efficiency: The use of advanced wires and connection methods can increase the operating speed of electronic devices and reduce energy consumption.
Support more complex system design: High-density connection capabilities provide support for complex system design and give full play to the performance of electronic devices. ‌
Promote innovation in the electronics industry: The application of HDI technology has promoted the innovation and development of the electronics industry, making electronic equipment more intelligent and efficient. ‌
Smaller size: It can complete a large number of circuit connections in a smaller space, meeting the needs of electronic products for lightness and portability. ‌
Higher signal transmission speed: The high-density line design allows signals to be transmitted quickly in a short time, improving the system operation speed and response speed.

Why does HDI PCB need via filling and plating?

‌Via filling plating plays a vital role in ‌HDI PCB manufacturing, with the main purpose of improving ‌electrical performance, connection reliability, operating frequency, and avoiding electromagnetic interference. This technology fills the blind holes of HDI PCB with conductive materials through the electroplating process to form a conductive path, which improves the performance and reliability of electronic equipment.

Improve electrical performance: Via filling plating can improve the electrical performance of HDI PCB, especially in high-frequency circuit board design, which is crucial for improving connection reliability, operating frequency and avoiding electromagnetic interference.
Via plugging and electrical interconnection in one step: Via filling plating technology combines via plugging and electrical interconnection, avoiding the defects caused by resin via filling, and also avoiding the CTE difference caused by other materials via filling.
Improve efficiency: Compared with resin via filling or other materials via filling, via filling plating has a simpler process and higher efficiency.
Process flow and technical challenges of via filling plating
Process flow: including steps such as tank preparation, setting of electroplating process control parameters, and analysis of potion addition.
Technical challenges: including positioning accuracy issues and electroplating quality issues, which need to be solved by strictly controlling parameters such as electroplating time and current density.

Application scenarios of hole filling electroplating

First-order HDI: Suitable for electronic devices with less complex circuits.
Second-order and above blind hole electroplating copper filling: Suitable for more complex electronic devices, such as mobile phones, laptops, etc.
Comparison between hole filling electroplating and full-board electroplating
Full-board electroplating: Although it can provide a uniform surface copper thickness distribution, it may encounter the problem of residual dry film on the board surface or in the hole during pre-treatment, resulting in some areas unable to be plated with copper. In addition, the etching process after full-board electroplating may cause quality defects such as side etching and fine lines.
Hole filling electroplating: Compared with full-board electroplating, hole filling electroplating is more accurate in filling blind holes, avoiding the problems that may be encountered in full-board electroplating, while simplifying the process and improving efficiency.

Materials of HDI PCB

The materials of HDI PCB mainly include coated copper foil (RCC), prepreg, copper foil, etc.

Resin-coated copper foil (RCC): This is a material that coats a special resin film layer on electroplated copper foil, used for HDI insulation layer. The characteristics of RCC include no glass dielectric layer, easy laser and plasma micro-hole forming, extremely high peel strength and good toughness, suitable for micro-narrow line etching. Laser drilling is performed on RCC, and the aperture shape formed is an inverted trapezoid, and the general aperture size is 0.076-0.10 mm. The use of RCC makes HDI PCB more widely used in small portable products, such as mobile phones, digital cameras, laptops, etc.

Prepreg and copper foil: These are basic materials in HDI PCB manufacturing, there are no special requirements, and they are suitable for different types of HDI PCB structures. The inner layer circuits are generally 1 ounce copper thick, while the outer layer circuits are plated with half an ounce of base copper to 1 ounce of finished copper thickness. The thickness of the board is usually thinner to meet the miniaturization requirements of HDI PCB.

Other materials: In addition to the main materials mentioned above, the manufacture of HDI PCBs may also involve other materials, such as FR4, PI (polyimide), BT, etc. These materials are selected according to specific application requirements. For example, FR4 has good electrical and mechanical properties and is suitable for most general applications; PI has higher heat resistance and chemical corrosion resistance, and is suitable for high temperature, high humidity and strong acid and alkali environments, but it is more expensive and difficult to process; BT combines good electrical properties, mechanical properties and thermal stability, and is suitable for application scenarios that require higher heat resistance.

Classification of HDI circuit boards

HDI circuit boards are mainly divided into first-order, second-order, third-order, high-order (including fourth-order and above) and Anylayer HDI. ‌

First-order HDI circuit boards mainly include single-sided or double-sided micro-hole processes, and the circuit layer has only one layer. ‌This type of HDI circuit board is suitable for applications with high requirements on cost and space, such as consumer electronics. ‌
Second-order HDI circuit boards contain two circuit layers, which are more complex but also more powerful than first-order HDI circuit boards. They can handle higher signal frequencies and are suitable for applications that require high performance, such as high-end communication equipment and computer hardware. ‌
Third-order HDI circuit boards contain three circuit layers. They are the most complex type at present. They can handle the highest signal frequency and the maximum data transmission rate. They are usually used in applications that require the highest performance, such as aerospace and military equipment. ‌
High-order HDI (including fourth-order and above) The applications of third-order or fourth-order HDI in electronic terminal products are more, while those above fourth-order are mostly converted to Anylayer structure. ‌
Anylayer HDI refers to HDI of any order/any layer. Compared with PCB boards with traditional lamination processes, HDI can reduce costs to a lower level when the stacking density exceeds eight layers. It also has higher electrical performance and signal accuracy, and significantly improves the performance of electromagnetic waves and radio frequency interference, electrostatic discharge and heat conduction in interconnection and relay transmission.

HDI PCB Process Flow

The process flow standards of HDI PCB mainly involve the application and processing technology of high-density interconnection technology (High Density Interconnection Technology, HDI for short), including first-order, second-order and third-order processes. Specifically, the HDI PCB process flow includes the following key steps and characteristics:

First-order process (1+N+1): This is a basic high-density interconnection technology that manufactures multi-layer boards through build-up and micro-blind via technology.

Second-order process (2+N+2): Further development on the basic technology, adding more layers and complexity.

Third-order process (3+N+3): Represents the highest stage of HDI technology, with extremely high layers and interconnection density

Differences between HDI PCB and ordinary PCBs

Differences in circuit design:
HDI PCB adopts a more sophisticated circuit design, with smaller line width and spacing, and smaller aperture, which can integrate more electronic components and realize more complex circuit functions. ‌
The blind, buried and stacked hole designs of HDI PCB greatly improve the utilization rate and signal transmission performance of the circuit board.
Differences in manufacturing process:
The manufacturing process of HDI PCB is more complicated, requiring high-precision processes such as laser drilling technology, hole filling electroplating technology and photolithography technology.
The manufacturing cost of HDI PCB is relatively high, but the performance and reliability are also higher. ‌
Differences in application:
Due to its high density and high performance, HDI PCB is widely used in high-end electronic products, such as smartphones, tablets, high-end communication equipment, etc.
Ordinary PCB is mainly used in low-end electronic products and general electronic equipment.
Characteristics and application scenarios of HDI PCB:
HDI PCB has high-density wiring, multi-layer structure, high-precision manufacturing process and excellent electrical performance, which can meet the extremely high requirements of high-end electronic products for size, weight, performance and reliability.
HDI PCB is widely used in smart phones, tablet computers, high-end communication equipment and other fields, promoting the continuous development and upgrading of electronic products.

Application of HDI PCB

HDI PCB (High Density Interconnection Printed Circuit Board) is widely used in multiple industries, including medical equipment, mobile phones, laptops, automotive electronics, computer industry, and future 5G technology fields

Medical equipment: The application of HDI PCB in medical equipment, such as sphygmomanometers and ultrasonic imaging systems, achieves accurate measurement of blood pressure and high-definition imaging of the internal structure of the body, providing patients with timely and accurate diagnosis and treatment information. ‌
Mobile phone industry: With the increasingly miniaturized design of mobile phones, HDI PCB is widely used in transceiver modules, motherboards, SIM card interfaces, fingerprint recognition modules and other parts of mobile phones due to its high density, high quality and high reliability. ‌
Computer industry: In the computer industry, the application of HDI PCB improves the performance of computers, especially in the fields of high-speed algorithms and multimedia applications, and adapts to the miniaturization trend of computer equipment2. ‌
Automotive electronics: HDI PCB has broad application prospects in the field of automotive electronics. In addition to the dominant mobile phone market, it also involves multiple fields such as automobiles, modules and artificial intelligence, demonstrating its key role in complex electronic systems. ‌
Future development trends: With the advent of 5G technology, the demand for HDI PCB will continue to increase, requiring higher speeds and frequencies while adapting to smaller and thinner device designs. Research new micro HDI PCB boards to adapt to future development trends. ‌

Tags: HDI circuit boards, HDI PCB, PCB
Posted in best pcb, bestpcb, FR4 PCB, HDI PCB | No Comments »

A Comprehensive Introduction to Ceramic Circuit Board

August 14th, 2024

Ceramic circuit board has almost completely integrated into our daily life, and it is filled with all kinds of electronic products we use every day. However, the production of ceramic circuit board is not so simple. The ceramic material itself is brittle, and it is easy to break in the process of through-hole, which easily leads to the scrapping of the whole board. However, this problem can’t stop the development of ceramic circuit board, and its position in the electronic industry is becoming more and more important. So do you know how ceramic circuit board was born?

History of ceramic circuit board

The history of ceramic circuit boards can be traced back to the early 1950s. At that time, with the appearance of transistors, single-sided ceramic circuit boards were developed centering on the United States. The main manufacturing method in this period is the direct etching of copper foil as the mainstream. From 1953 to 1955, Japan made paper-based phenolic copper foil substrates from imported copper foil for the first time, and it was widely used in radios and other aspects. Subsequently, the emergence of professional circuit board manufacturers in Japan made the manufacturing technology of single panel progress rapidly, and ceramic circuit boards also entered the development stage. ‌

In the development process of ceramic circuit board, it has experienced the transformation from single panel to double panel. Compared with single panel, double panel has wiring on both sides, and leads on both sides are connected through guide holes, which is suitable for more complex circuits. There is more flexibility in the design of double-panel circuits, because the wiring can be carried out on both sides and staggered with each other, which increases the complexity of circuit design but also improves the performance and function of the circuit. ‌

What are the problems faced by traditional pcb circuit boards? ‌

With the increasing variety of electronic products, it is necessary to use the circuit board in assembly, but the first problem that has to be faced is the heat dissipation of the circuit board. With the continuous expansion of the application scope of VLSI and the development trend of SMT, the design of organic laminated PCB is facing the challenge of heat dissipation, which is because the thermal conductivity of most ordinary PCBs is low. However, the thermal conductivity of ceramics is 90 times that of epoxy glass fiber, and it has excellent conduction cooling effect. Moreover, components on ceramic PCB usually have a lower junction temperature than ordinary PCB.

Secondly, there is another problem that needs to be faced, which is the CTE compatibility challenge. SMT technology, which became popular in the first half of 1980s, is affecting the whole electronic assembly industry. Because SMT technology directly welds electronic components on both sides of PCB, compared with THT (through hole technology), SMT technology has lower cost, higher reliability and easier automation, which can reduce the circuit size by five-sixths. Some reliable packages, such as LCC (leadless chip carrier), are very compatible with SMT requirements, but they usually cannot withstand the challenges brought by thermal cycling. Therefore, LCC is questioned from package reliability to on-board interconnection, because the CTE (coefficient of thermal expansion) incompatibility between LCC and PCB materials leads to welding failure. Therefore, ceramic PCB came into being. Ceramic PCB can provide the best solution to overcome thermal cycle failure, because they share compatible CTE with leadless ceramic chip carriers, and have higher thermal conductivity, higher stability and inertness.

Characteristics of ceramic circuit board

Compared with the traditional pcb based on phenolic resin (FR-4), glass fiber cloth (GPP), polytetrafluoroethylene (PTFE), epoxy glass fiber and polyimide, ceramic circuit board has superior thermal conductivity, high mechanical strength and durability, excellent electrical insulation and high dielectric strength.

With the development of multi-function, miniaturization, speediness and large-scale electronic equipment, stricter requirements are put forward for the durability, thermal conductivity, dielectric constant and electrical insulation of ceramic PCB. It can be predicted that the demand for ceramic PCB with aluminum nitride, alumina and glass ceramics as substrate materials will be increasing, and the market for ceramic circuit boards will be wider and wider.

What are the types of ceramic circuit boards?

At present, the common types of ceramic circuit boards are HTCC, LTCC, DBC, DPC, AMB, TFC (thin film ceramic board) and TPC (thick film ceramic board).

1. HTCC is an early developed technology. However, due to the high sintering temperature (1300~1600℃), the selection of electrode materials is limited, and the manufacturing cost is relatively expensive, which makes the development of HTCC slow.

2. Although LTCC reduces the co-firing temperature to about 850℃, it has the disadvantage that dimensional accuracy and product strength are not easy to control.

3. DBC combines Al2O3 with Cu plate by high temperature heating. Its technical bottleneck is that it is not easy to solve the problem of micro-pores between Al2O3 and Cu plate, which makes the mass production energy and yield of this product greatly challenged.

4. DPC technology is to deposit Cu on Al2O3 substrate by direct copper plating technology. Its technology combines material and thin film technology, and its products are the most commonly used ceramic heat dissipation substrate in recent years. However, its ability of material control and process technology integration is high, which makes the technical threshold for entering DPC industry and stable production relatively high. DBC&DPC is a professional technology that has only been developed and matured in recent years in China and can be mass-produced.

5. AMB ceramic copper clad laminate adopts AMB active brazing process, and the bonding force of copper layer is higher than DPC, which is above 18n/mm and as high as 21 N/mm.. AMB ceramic copper clad laminate usually has high bonding force, and the copper is usually thick, ranging from 100 μ m to 800 μ m, and it is rarely used for wiring or punching. Even if there are wires, it is very simple and the spacing is relatively wide.

6. TFC thin-film ceramic substrate generally adopts sputtering process to directly deposit metal layer on the surface of ceramic substrate. If photolithography, development, etching and other processes are assisted, the metal layer can also be patterned and prepared into lines. Because the deposition speed of sputtering coating is low (generally less than 1um/h), the thickness of the metal layer on the surface of TFC substrate is small (generally less than 1um), and ceramic substrates with high graphic accuracy (line width/line spacing less than 10um) can be prepared. It is mainly used for packaging small current devices in the field of laser and optical communication.

7. TPC thick film ceramics is a method of forming conductive lines and electrodes by screen printing, directly depositing slurry on the substrate and sintering at high temperature. This method is suitable for most ceramic substrates. After high temperature sintering, the material will form a firmly adhered film on the ceramic circuit board, and after repeated for many times, it will form a circuit with multi-layer interconnection structure containing resistance or capacitance. The advantage of this technology is that the process is simple, but the disadvantages are obvious: the conductors are gold paste and silver paste, limited by the size of conductive paste and screen, the minimum wire width of the product is difficult to be less than 100μm, and it is impossible to make three-dimensional graphics, so it is not suitable for the production of fine circuit boards.

Where is the ceramic circuit board used?

1. LED lighting

2. Power electronics

3. Aerospace

4. Automotive Electronics

5. Medical equipment

6. high frequency communication

7. chemical equipment

8. industrial electronics

Ceramic circuit boards are widely used in all walks of life because of their unique properties, especially in the electronic circuit industry.

Since its birth, ceramic circuit boards have been widely used. With the development of electronic industry, in order to adapt to the application of special industries, the types of ceramic circuit boards have become more and more diverse. As a professional manufacturer of ceramic circuit boards, BEST Technology is committed to providing high-quality products and comprehensive technical support. For different types of ceramic circuit boards, BEST Technology also has professional equipment and personnel to produce them. Choose a powerful manufacturer of ceramic circuit boards, and you will have no worries.

Tags: ceramic circuit board
Posted in best pcb, bestpcb, Ceramic PCB | No Comments »

A Short Guide to Soldering Wire Material

August 14th, 2024

Soldering wire material refers to the specific metals or alloys used to create the solder wire. This wire is essential in joining metal parts, primarily in electronics. The material is designed to melt at a specific temperature, bonding components together securely once it cools. Different materials offer various properties, making them suitable for specific applications.

A Short Guide to Soldering Wire Material

Types of Soldering Wire Material

Tin-Lead Solder (Sn-Pb)
Lead-Free Solder
Silver Solder
Copper Solder
Bismuth Solder
Aluminum Solder
Rosin-Core Solder
Acid-Core Solder

Solder Properties

1. Melting point

One of the most significant properties of solder is its melting point. The melting point of solder must be lower than that of the materials being joined. Traditional tin-lead solder melts at around 183°C (361°F), while lead-free solder, often composed of tin with copper or silver, melts at a slightly higher temperature, typically between 217°C (423°F) and 221°C (430°F).

2. Electrical conductivity

The composition of the solder, particularly the percentage of tin, plays a significant role in its ability to conduct electricity efficiently. Tin-based solders offer high conductivity, ensuring that the electrical connections remain stable and reliable.

3. Thermal conductivity

Besides electrical conductivity, solder also has good thermal conductivity. It helps prevent overheating and potential damage to the electronic components being joined.

4. Mechanical strength

Solder joints need to be hard enough to withstand physical stress, vibrations, and thermal expansion without breaking or weakening. The alloy composition, especially the amount of tin and any additional metals like silver, contributes to the overall strength of the solder.

5. Corrosion resistance

Solder alloys are often designed to resist oxidation and corrosion, with lead and tin providing good resistance. However, lead-free solders may require additional coatings or treatments to ensure long-term corrosion resistance, especially in harsh environments.

6. Wettability

Wettability refers to the ability of the molten solder to flow and adhere to the surfaces being joined. Good wettability ensures that the solder spreads evenly, creating a solid and uniform joint. A solder with poor wettability might result in weak or incomplete joints, leading to unreliable connections.

7. Flow characteristics

The flow characteristics of solder describe how easily it melts, flows, and fills the gaps between the components being soldered. Solder with good flow characteristics ensures that the joint is completely filled, minimizing the risk of voids or weak spots.

8. Ductility

A ductile solder can absorb some of these forces, reducing the risk of cracks or fractures in the joint. Tin-based solders are generally quite ductile, making them suitable for a wide range of applications, including those requiring some flexibility in the joint.

Is Soldering Wire Made of Lead?

Traditional soldering wire was commonly made with a mixture of tin and lead. However, due to the toxic nature of lead, many industries have switched to lead-free alternatives. Lead-based solder is still available but is used less frequently, especially in consumer electronics, where regulations have pushed for safer alternatives.

What is the Best Metal Wire for Soldering?

The best metal wire for soldering depends on the specific application. For general electronics work, a lead-free tin-copper wire is often the best choice due to its balance of performance and safety. For more specialized tasks, such as soldering sensitive components, a tin-silver or tin-copper-silver alloy might be preferred for its lower melting point and superior electrical conductivity.

What is Solder Used For?

Solder is used to create secure, conductive connections between metal components. It is most commonly used in electronics to connect wires and components to circuit boards. Solder can also be used in plumbing, jewelry making, and other applications where a strong, conductive bond between metals is required. Here are some common applications:

Electronics assembly
Plumbing
Jewelry making
Stained glass
Automotive repair
Aerospace and military applications
Electrical wiring

What is Lead-Free Solder Made of?

Lead-free solder is primarily composed of tin (Sn), which acts as the base metal, combined with other metals such as copper (Cu), silver (Ag), or bismuth (Bi) to enhance specific properties. The exact composition of lead-free solder varies depending on the intended application, but some of the most common alloys include:

1. Tin-Copper (Sn-Cu)

One of the most basic and cost-effective lead-free solder compositions, tin-copper solder typically contains about 99.3% tin and 0.7% copper. This alloy is widely used for general-purpose soldering in electronics and plumbing due to its relatively low melting point (around 227°C or 441°F) and good mechanical strength.

2. Tin-Silver-Copper (Sn-Ag-Cu or SAC)

Often referred to as SAC solder, this alloy is a popular choice in electronics manufacturing. It usually consists of 96.5% tin, 3% silver, and 0.5% copper. SAC alloys offer excellent mechanical properties, including high tensile strength and good thermal fatigue resistance, making them ideal for soldering in environments where components are subject to repeated thermal cycling. The melting point of SAC solder is around 217°C to 221°C (423°F to 430°F).

3. Tin-Bismuth (Sn-Bi)

Tin-bismuth solder is another common lead-free alloy, typically containing about 42% tin and 58% bismuth. This alloy has a lower melting point (around 138°C or 280°F) compared to other lead-free solders, making it suitable for soldering heat-sensitive components. It is also used in applications where low-temperature soldering is necessary, such as in surface-mount technology (SMT).

4. Tin-Silver (Sn-Ag)

Tin-silver solder, typically composed of 96.5% tin and 3.5% silver, is known for its high electrical and thermal conductivity. It has a melting point of around 221°C (430°F) and is often used in applications where reliability and durability are critical, such as in medical devices, aerospace, and high-performance electronics.

5. Tin-Zinc (Sn-Zn)

Tin-zinc solder is often used for aluminum soldering due to its ability to create strong bonds with aluminum surfaces. This alloy usually contains about 91% tin and 9% zinc, with a melting point of approximately 199°C (390°F). It’s less common in electronics but is valuable in specific industrial applications.

Is Solder Toxic?

Lead-based solder can be toxic, particularly if ingested or inhaled as fumes during the soldering process. Lead-free solder is less toxic but still requires proper ventilation and handling. It’s important to work in a well-ventilated area and to wash hands after handling solder to minimize any potential risks.

How Do I Choose the Right Solder Wire?

First, choose the right diameter. Generally speaking, the smaller the diameter of the solder wire is used for small electronic parts welding, and the larger the diameter of the solder wire is used for large parts welding. Welding wires with a diameter of 0.8mm or 1.0mm are usually selected, which are easier to control and easier to weld.

Secondly, pay attention to the tin content of the solder wire. The higher the tin content of the solder wire is more smooth when welding, the quality is more stable, but the price is relatively high. For some conventional small electronic parts welding, you can choose a solder wire with a tin content of 60% to 63%.

Also consider the conditions of welding work. If you work outdoors or in a high temperature environment or the component can withstand higher temperatures, you can choose a solder wire with a higher melting point, and if you work in a low temperature environment or the component can withstand lower temperatures, you need to choose a solder wire with a lower melting point. In addition, factors such as quality stability and corrosion resistance should be considered.

The last thing to choose is a reliable brand. The quality of brands varies greatly, and some brands of solder wire may have problems such as solder wire oxidation and lead not smooth, which can easily lead to poor welding and inconvenient use. Therefore, it is recommended to choose well-known brands or brands with reputation. At the same time, pay attention to the packaging and label when purchasing to ensure the authenticity and ease of management of the product.

There is not to blindly pursue cheap goods, it is best to use the electronic scale to weigh the weight, if possible, you can use the detector to detect the tin content, so that you can avoid the loss caused by false information.

What Type of Solder Must Never Be Used to Solder Wires?

When it comes to soldering wires, choosing the right type of solder is essential for creating strong, reliable connections. However, there is a specific type of solder that should never be used to solder wires: acid-core solder.

Acid-core solder contains an acid-based flux, which is highly effective at cleaning metal surfaces and removing oxidation. This aggressive cleaning action makes acid-core solder suitable for certain types of metalwork, such as plumbing, where it is used to solder copper pipes and fittings. However, the corrosive nature of the acid flux makes it unsuitable for electrical and electronic applications, including soldering wires.

Posted in best pcb, bestpcb, FAQ | No Comments »

What is the thickness of copper used in PCB manufacturing?

August 14th, 2024

PCB copper thickness is generally divided into 1OZ (35um), 2OZ (70um), 3OZ (105um), of course, there are thicker ones. The copper thickness depends on what kind of board you are making. For example, 2OZ is enough for switching power supplies with high current, and 1OZ is enough for general signals.
Generally, double-sided boards are 1oz
Multi-layer boards are generally 1/2oz 1/3oz for the inner layer and 1oz 1/2oz 1/3oz for the outer layer

0.5 oz copper thickness About 0.685 mm.
1 ounce is about 1.37 mm, so 1.37÷2=0.685,
0.5 oz copper thickness in mm About 0.685 mm

1 oz copper thickness: This is the most common and basic copper thickness standard, also known as standard copper thickness. 1 oz copper thickness refers to the weight of 1 ounce (about 35.3 grams) of copper foil per square foot of board area, and the corresponding copper foil thickness is about 1.4 mils (0.035mm). This copper thickness is suitable for most common circuit board designs and applications.

2 oz copper thickness: 2 oz copper thickness refers to the weight of 2 ounces (about 70.6 grams) of copper foil per square foot of board area, and the corresponding copper foil thickness is about 2.8 mils (0.071mm). This copper thickness is suitable for some applications that require higher current carrying capacity, such as power electronic devices and high-power LEDs.

3 oz copper thickness: 3 oz copper thickness refers to the weight of 3 ounces (about 105.9 grams) of copper foil per square foot of board area, and the corresponding copper foil thickness is about 4.2 mils (0.107mm). This copper thickness is suitable for some special applications that require higher current carrying capacity, such as high-power amplifiers and high-power power supplies.

PCB copper foil thickness standard

Common international PCB thicknesses are: 35um, 50um, and 70um.
The copper foil (copper cladding) thickness of general single-sided and double-sided PCBs is about 35um (1.4mil), and the other specifications are 50um and 70um.
The surface thickness of multilayer boards is generally 35um=1oz (1.4mil), and the inner layer is 17.5um (0.7mil).

The relationship between the line width, copper thickness and current passing through the PCB board

1 foot = 12 inches
1 inch = 1000 mil
1mil = 25.4um
1mil = 1000uin mil is sometimes called inch
1um = 40uin (some companies call microinches “microinches”, which are actually microinches)
1OZ = 28.35 grams per square foot = 35 microns

PCB copper thickness current comparison table

Copper foil width Copper foil thickness
70um 50um 35um
2.50mm 6.00A 5.10A 4.50A
2.00mm 5.10A 4.30A 4.00A
1.50mm 4.20A 3.50A 3.20A
1.20mm 3.60A 3.00A 2.70A
1.00mm 3.20A 2.60A 2.30A
0.80mm 2.80A 2.40A 2.00A
0.60mm 2.30A 1.90A 1.60A
0.50mm 2.00A 1.70A 1.35A
0.40mm 1.70A 1.35A 1.10A
0.30mm 1.30A 1.10A 0.80A
0.20mm 0.90A 0.70A 0.55A
0.15mm 0.70A 0.50A 0.20A

PCB copper content

The copper content of PCB copper foil is generally 90% and 88%.

Copper foil is made of copper and a certain proportion of other metals. There are two common specifications of copper foil, namely 90% and 88% copper content. The size of these two specifications of copper foil is 16*16cm, which is widely used in various occasions where copper foil is needed, including PCB manufacturing. In PCB manufacturing, copper foil is the basic material of the circuit board, and its thickness and copper content have an important influence on the electrical performance and durability of the circuit board. The thickness of copper foil is usually expressed in OZ (ounces). The standard PCB copper thickness range is 1/4OZ-6OZ. The specific thickness includes 1OZ, 2OZ, 3OZ, 4OZ, 5OZ, 6OZ, which correspond to different copper thickness sizes, such as 35um, 70um, 105um, 140um, 175um, 210um. In practical applications, the commonly used copper thicknesses are 1OZ, 2OZ, 3OZ, 4OZ, etc. These copper thicknesses can meet the needs of most electronic products.

Why is the copper foil on the surface of PCB copper+plating?

The copper foil on the surface of the PCB adopts the copper+plating method, mainly because this treatment method can provide better conductivity and protection circuit. ‌Copper foil is the conductor of PCB, and its basic material is copper, while plating (plating) is a layer of metal added on the basis of copper foil by electroplating or other methods, usually tin, gold or other alloys, to provide additional protection and enhance electrical performance. ‌The reasons and advantages of this treatment method are as follows: ‌

Conductivity: Copper has good conductivity and is an ideal medium for the flow of electrons. ‌In PCB, copper foil is used as a conductive layer to connect various electronic components and ensure smooth transmission of current. ‌
Protective circuit: By adding plating, such as tin or gold, to the copper foil, additional protection can be provided to prevent the copper foil from being oxidized or corroded, thereby protecting the long-term stability and reliability of the circuit board. ‌
Enhanced electrical performance: Plating not only prevents copper foil from being oxidized, but also enhances electrical performance by selecting appropriate plating materials, such as using gold plating to improve the corrosion resistance and conductivity of the circuit board. ‌
Cost considerations: Although gold is an expensive metal, the use of gold plating in certain key signal lines or high-density interconnection areas can significantly improve the performance and reliability of the circuit board, especially in reducing signal loss and interference in high-frequency signal transmission.

Tags: copper thickness, PCB
Posted in best pcb, bestpcb, PCB News | No Comments »

What is SMT Process in PCB Manufacturing? – Best Technology

August 14th, 2024

SMT process is one of the most commonly used processes in PCBA or box build assembly products. It also called surface mount process. It is reliable connection between electronic components and printed circuit boards can be realized through the precise mounting and welding technology of the SMT machine.

What is an SMT Process?

The SMT process is a method used to mount electronic components directly onto the surface of a printed circuit board (PCB). Unlike traditional through-hole technology, where components are placed in drilled holes, SMT components are placed on the board’s surface.

SMT enables the creation of smaller devices without compromising performance. By eliminating the need for drilled holes, it also speeds up production, reducing costs and improving efficiency.

What is SMT Process in PCB Manufacturing? - Best Technology

What is the Purpose of SMT?

The primary purpose of SMT is to streamline the manufacturing process while enhancing the functionality and reliability of electronic devices. SMT allows manufacturers to produce smaller, more complex circuits that are essential for today’s technology-driven world. From smartphones to medical devices, SMT plays a critical role in the development of products that we rely on daily.

Moreover, SMT offers flexibility in design, allowing engineers to create intricate circuits that would be impossible with traditional methods. The process also supports higher levels of automation, reducing the risk of human error and ensuring consistent quality across large production runs. In essence, SMT is about improving efficiency, quality, and innovation in electronics manufacturing.

Terms Related to SMT

Solder Paste

A mixture of powdered solder and flux used to bond SMT components to the PCB. It’s applied to the board using a stencil and is essential for creating strong, reliable connections.

Pick and Place Machine

An automated machine that picks up components and places them onto the PCB with high precision. This machine is vital in ensuring that components are positioned accurately before soldering.

Reflow Oven

After the components are placed on the PCB, the board is passed through a reflow oven. The heat melts the solder paste, securing the components in place.

Stencil

A metal or plastic template used to apply solder paste to specific areas of the PCB. The stencil ensures that the paste is only applied where needed, preventing defects.

Flux

A chemical agent that cleans the surfaces of the components and the PCB, ensuring a strong bond during the soldering process.

PCB

The bare board without any components on its surface. The board that serves as the foundation for electronic components. It has conductive pathways that connect the components and allow them to function together.

PCBA

When a PCB is surface-mounted or through-hole-mounted with components, we call this semi-finished product a PCBA. It can further assemble with other PCBAs and an enclosure to become a complete product or box-build we call it.

SMD

Surface mount device, it is an electronic component for SMT manufacturing. Compared with PTH components for PTH assembly, SMDs have a much smaller weight and size about 1/10 of a PTH component of the same function.

How Many Steps are in the SMT Process?

The SMT process involves several detailed steps, each essential for ensuring the quality and reliability of the final electronic product. Below is a comprehensive look at these steps:

Step 1: Components Incoming Inspection

Before the assembly begins, all components undergo an incoming inspection. This step is crucial to ensure that all parts meet the required specifications. It helps in identifying any defects or discrepancies in the components, which could affect the final product’s quality.

Step 2: PCB Quality Control

The next step is to inspect the PCB itself. This involves checking for any manufacturing defects, such as scratches, misalignments, or irregularities in the copper layers. Ensuring the PCB is flawless is vital because any defect can lead to failure in the final assembly.

Step 3: Stencil Preparation

Stencil preparation is critical for the accurate application of solder paste. The stencil must be aligned correctly with the PCB to ensure the solder paste is applied precisely to the pads where components will be placed. This accuracy is key to avoiding soldering defects.

Step 4: Solder Paste Applying

Solder paste is applied to the PCB through the stencil. The paste contains tiny balls of solder mixed with flux, and it’s applied to the areas where components will be soldered. Proper application of the solder paste is essential for creating reliable solder joints.

Step 5: SPI (Solder Paste Inspection)

After applying the solder paste, it’s inspected using SPI (Solder Paste Inspection) equipment. This step checks the volume, height, and position of the solder paste on the PCB. Any deviations from the ideal paste deposit can lead to defects, so this inspection helps ensure consistency and quality.

Step 6: Pick and Place Components

The pick and place machine automatically places components onto the PCB. Misplaced components can lead to electrical failures, so this step is critical for the overall success of the process.

Step 7: Reflow Soldering

Once the components are placed, the PCB is passed through a reflow oven. The heat in the oven melts the solder paste, creating a solid electrical connection between the components and the PCB. The reflow process must be carefully controlled to avoid overheating or insufficient soldering.

Step 8: AOI (Automated Optical Inspection)

After reflow soldering, the board undergoes AOI. This inspection process uses cameras to check for soldering defects, such as bridges, misaligned components, or insufficient solder. AOI helps catch defects early, reducing the chances of failures in the final product.

Step 9: X-RAY (Only for BGA or Fine-Pitch Components)

For boards with Ball Grid Array (BGA) or fine-pitch components, an X-ray inspection is performed. This step allows for the inspection of solder joints that are hidden beneath the components, ensuring that they are properly formed and free of defects.

Step 10: FAI (First Article Inspection)

The first board produced in a batch undergoes FAI, where it is thoroughly inspected to ensure that all processes and setups are correct. This step serves as a final check before full production begins, helping to confirm that everything is in order.

Step 11: Function Testing

The final step in the SMT process is function testing. This involves testing the completed PCB to ensure it functions as intended. Function testing is essential to verify that the board meets the required specifications and operates correctly in its intended application.

SMT Process Flow Chart

A flow chart is a visual representation of the SMT process, showing each step in sequence. This chart is essential for understanding how the process works and identifying potential areas for improvement. Here’s a basic flow chart of the SMT process:

How Do I Prepare for SMT?

Preparing for the SMT process requires careful planning and attention to detail. Here are some tips to help you get ready:

Design for Manufacturability (DFM)
Material selection
Stencil
Equipment calibration
Quality control
Training

Best Technology – Your Turn-key PCB & PCBA Supplier

At Best Technology, we offer a range of value-added services, including IC programming, functional testing, conformal coating, thermal aging, and box-build assembly, ensuring you receive fully assembled and ready-to-use electronic products.

Additionally, you can reduce fabrication costs without compromising on function or quality. If needed, Best Technology can source alternative components with equivalent functions and certifications to replace more expensive parts as well.

Tags: smt process, surface mount process
Posted in best pcb, bestpcb, FAQ, PCBA, SMT Technology | No Comments »

TDA7294 Amplifier Board: A Comprehensive Introduction

August 13th, 2024

The TDA7294 amplifier board is a functional and widely used audio amplifier. It is based on the TDA7294 integrated circuit (IC), a high-power, low-distortion audio amplifier IC developed by STMicroelectronics. This IC is designed to deliver high-quality audio output with minimal distortion, making it a popular choice for DIY audio enthusiasts and professionals alike.

What is TDA7294 IC Amplifier Board?

The TDA7294 IC is capable of delivering up to 100 watts of power in a single-ended or bridged configuration, making it suitable for a wide range of audio applications, from home audio systems to professional audio equipment. The amplifier board typically includes the TDA7294 IC along with supporting components such as capacitors, resistors, and heatsinks, all mounted on a printed circuit board (PCB). This board is designed to simplify the process of building a powerful and reliable audio amplifier by providing a pre-configured layout that ensures optimal performance.

TDA7294 Amplifier Board: A Comprehensive Introduction

Features of TDA7294 Amplifier Board

The TDA7294 amplifier board provides several key features that make it a popular choice for high-quality audio amplification.

High Output Power
Low Distortion
Built-in Protection Circuits
Thermal Management
Low Noise and High Signal-to-Noise Ratio (SNR)
Ease of Integration
Flexible Configuration
Improved Reliability
Compact Size

TDA7294 Amplifier Circuit Diagram

The circuit diagram of the TDA7294 amplifier is a crucial element for anyone looking to build or understand this amplifier. The diagram typically includes the TDA7294 IC at the core, surrounded by components that shape the audio signal and manage power delivery. Key components include capacitors for signal coupling and power supply smoothing, resistors for setting gain and biasing, and inductors or filters for noise reduction.

The TDA7294 IC itself has several pins that serve specific functions in the circuit. For instance, the input pin receives the audio signal, while the output pin sends the amplified signal to the speakers. Power supply pins connect to the positive and negative voltage rails, and other pins might be used for muting, standby, or feedback purposes.

When assembling the circuit, careful attention must be paid to the placement of components and routing of traces on the PCB to minimize noise and maximize performance. The layout of the circuit diagram ensures that the amplifier delivers clean, high-fidelity sound with minimal distortion, which is a key selling point for the TDA7294.

TDA7294 Specification

Symbol	Parameter	Test condition	Min. value	Typical value	Max. value	Unit
Vs	Power Supply		±10		±40	V
lq	Current Consumption		20	30	60	mA
Vos	Input Offset Voltage				500	mV
los	Input Offset Current				±100	nA
Po	Continuous Power Output	VS = ± 35V, RL = 8Ω; VS = ± 31V, RL = 6Ω; VS = ± 27V, RL = 4Ω;	60	70		W
d	THD	PO = 5W; f = 1kHz PO = 0.1 to 50W; f = 20Hz to 20kHz		0.005	0.01	%
d	THD	VS = ±27V, RL = 4W: PO = 5W; f = 1kHz PO = 0.1 to 50W; f = 20Hz to 20kHz		0.01	0.01	%
SR	Switching rate		7	10		V/us
Gv	Open Loop Voltage Gain			80		dB
Gv	Closed Loop Voltage Gain		24	30	40	dB
fL, fH	Frequency Response (-3dB)	Po=1W	20Hz to 20kHz
Ri	Input Resistance		100			KΩ

TDA7294 Pinout

The TDA7294 IC comes with a specific pinout configuration that plays a crucial role in its operation. The chip has 15 pins, each with a designated function:

Pin 1 (IN+): Non-inverting input

Pin 2 (SVR): Supply voltage rejection

Pin 3 (IN-): Inverting input

Pin 4 (MUTE): Mute function

Pin 5 (ST-BY): Standby function

Pin 6 (VCC+): Positive supply voltage

Pin 7 (OUT): Output

Pin 8 (GND): Ground

Pin 9 (BOOTSTRAP): Bootstrap capacitor

Pin 10 (NC): Not connected

Pin 11 (VCC-): Negative supply voltage

Pin 12 (DIAG): Diagnostics pin

Pin 13 (BOOTSTRAP): Bootstrap capacitor

Pin 14 (GND): Ground

Pin 15 (OUT): Output

TDA7294 Datasheet

The TDA7294 datasheet is a critical resource for anyone working with this IC. It provides detailed information about the IC’s electrical characteristics, pin configurations, thermal properties, and recommended operating conditions. The datasheet also includes typical application circuits, which can serve as a starting point for designing your own amplifier.

In addition to technical specifications, the datasheet often includes practical advice on PCB layout, component selection, and thermal management. Following these guidelines can help you achieve the best possible performance from your TDA7294 amplifier board.

How Many Watts is a TDA7294 Output?

The TDA7294 IC is capable of delivering up to 100 watts of output power when configured in a single-ended or bridged amplifier circuit. The actual output power depends on several factors, including the supply voltage, load impedance, and heat dissipation. In a typical configuration with a supply voltage of ±35V and an 8-ohm load, the TDA7294 can deliver around 70 watts of continuous power.

For higher power output, the IC can be used in a bridged configuration, where two TDA7294 ICs are combined to drive a single load. In this setup, the output power can reach up to 150 watts, making it suitable for driving larger speakers or subwoofers.

It’s important to note that the power rating of the TDA7294 should be matched to the speakers and other components in your audio system. Overloading the IC by driving it at maximum power for extended periods can lead to overheating and potential damage, so proper thermal management is essential.

What is the Equivalent of TDA7294?

When looking for an equivalent to the TDA7294, there are a few other audio amplifier ICs that offer similar performance characteristics. Some of the commonly considered alternatives include:

LM3886

This is another high-power audio amplifier IC that delivers up to 68 watts of output power. It’s known for its low distortion and high fidelity, making it a popular choice for DIY audio projects.

TDA7293

This IC is very similar to the TDA7294, with slightly different electrical characteristics. It can be used as a drop-in replacement in many circuits, offering similar power output and performance.

TDA2030

While not as powerful as the TDA7294, this IC is a good alternative for lower-power applications. It delivers up to 20 watts of output power and is widely used in small audio amplifier projects.

Each of these alternatives has its strengths and weaknesses, so the best choice depends on the specific requirements of your project. For instance, if you need higher output power, the LM3886 might be a better option, while the TDA2030 is more suitable for compact, low-power designs.

What is the Maximum Voltage for TDA7294 IC?

The maximum supply voltage for the TDA7294 IC is ±50V. However, for optimal performance and reliability, it’s recommended to operate the IC at a lower voltage, typically around ±35V to ±40V. Operating at the maximum voltage can increase the risk of overheating and may require additional cooling measures, such as larger heatsinks or active cooling.

The voltage rating is crucial for ensuring the longevity and performance of the amplifier. Exceeding the maximum voltage can cause the IC to fail, leading to permanent damage. Therefore, it’s important to choose a power supply that matches the recommended voltage range for the TDA7294.

In addition to the supply voltage, the IC’s thermal management is also important. Ensuring adequate cooling through heatsinks or ventilation can prevent overheating and ensure stable operation, especially when driving the amplifier at high power levels.

What is TDA in an Amplifier?

The TDA prefix in TDA7294 refers to the series of audio amplifier ICs developed by STMicroelectronics. These ICs are designed to provide high-quality audio amplification with minimal distortion and noise. The TDA series includes a range of ICs with varying power output capabilities, making them suitable for different audio applications, from small portable speakers to large home audio systems.

In an amplifier, the TDA IC is responsible for amplifying the audio signal from a low-level input to a high-level output that can drive speakers. The IC’s internal circuitry is optimized for audio performance, ensuring that the amplified signal remains clear and distortion-free.

The TDA series is widely regarded for its reliability and performance, making it a popular choice for both commercial and DIY audio projects. Whether you’re building a simple audio amplifier or a more complex audio system, the TDA7294 and its counterparts offer a solid foundation for high-quality sound.

FAQs

1. Can the TDA7294 be used in a car audio system?

Yes, the TDA7294 can be used in car audio systems, but you need to ensure that the power supply provides the correct voltage and current. Car audio systems typically operate at 12V, so a step-up converter might be needed to reach the required supply voltage.

2. How do I connect multiple TDA7294 ICs for higher power output?

You can connect multiple TDA7294 ICs in a bridged configuration to increase the power output. This involves using two ICs to drive a single load, effectively doubling the output power.

3. What is the typical distortion level of the TDA7294?

The TDA7294 has a low distortion level, typically around 0.005% at 1kHz, making it suitable for high-fidelity audio applications.

4. Is the TDA7294 suitable for subwoofers?

Yes, the TDA7294 is suitable for driving subwoofers, especially in a bridged configuration where it can deliver high power output with low distortion.

5. Can I use the TDA7294 with a passive cooling system?

While the TDA7294 can be used with a passive cooling system, it’s important to ensure that the heatsink is large enough to dissipate the heat generated during operation. For higher power levels, active cooling may be necessary to prevent overheating.

Tags: TDA7294, tda7294 amplifier board
Posted in best pcb, bestpcb, FAQ, PCBA, SMT Technology | No Comments »

HASL Lead Free vs ENIG: Understanding Their Differences

August 13th, 2024

When it comes to PCB surface finishes, choosing the right one is essential for the longevity and performance of your circuit board. Among the many options available, two of the most popular are Hot Air Solder Leveling (HASL) and Electroless Nickel Immersion Gold (ENIG). These two methods offer distinct advantages depending on the application, and understanding their differences can help you select the best finish for your project.

HASL Lead Free vs ENIG: Understanding Their Differences

What Does HASL Stand For?

HASL stands for Hot Air Solder Leveling. It is a surface finish process used in PCB manufacturing. The term describes the method where solder is applied to the copper pads on a PCB and then leveled using hot air to ensure even coating. HASL is widely used because of its simplicity and effectiveness in providing a reliable solderable surface.

What Is HASL in PCB?

In PCB manufacturing, HASL is a surface finish applied to the exposed copper pads to protect them from oxidation and to provide a good surface for soldering components. The HASL process involves dipping the PCB into molten solder, typically composed of a lead-free alloy, and then using hot air to remove excess solder, ensuring a smooth and even layer. This finish is particularly valued for its excellent solderability and cost-effectiveness.

Characteristics of Hot Air Solder Leveling

Hot Air Solder Leveling is a widely used surface finish in PCB manufacturing due to its unique set of characteristics that make it suitable for various applications. Below are the key attributes that define HASL:

1. HASL provides one of the most solderable surfaces available for PCB assembly. The molten solder applied during the HASL process creates a coating that is highly receptive to soldering, making it easy to attach components.

2. Compared to other surface finishes like ENIG or OSP, HASL is generally more affordable.

3. The solder coating provided by HASL serves as a protective layer for the copper pads on the PCB. This layer helps prevent oxidation and corrosion.

4. Variability in coating thickness. The hot air leveling process can result in uneven distribution of solder, leading to variations in thickness across the PCB. While this might be a drawback for designs requiring fine-pitch components or precise tolerances, it is often acceptable in less demanding applications where slight variations are not critical.

5. Thermal resistance. The solder layer provided by HASL can withstand multiple thermal cycles during the PCB assembly process, such as during solder reflow.

6. The HASL process creates a strong bond between the solder and the underlying copper pads.

What Is the HASL Method?

The HASL coating process is a critical step in PCB manufacturing, designed to protect the exposed copper pads and good solderability during the assembly of electronic components. The process is under several steps, each carefully controlled to achieve a uniform and reliable coating. Here’s a detailed look at how HASL is applied to a PCB:

1. Pre-Cleaning the PCB

The HASL process begins with thoroughly cleaning the PCB to remove any contaminants such as oxidation, oils, or residues from previous manufacturing steps. This is typically done using a combination of chemical cleaning agents and mechanical scrubbing.

2. Flux Application

After cleaning, a layer of flux is applied to the PCB. Flux is a chemical agent that serves multiple purposes: it removes any remaining oxidation from the copper pads, improves the wetting of the solder, and helps the solder adhere more effectively to the copper. The type of flux used can vary, but it must be compatible with the solder alloy to ensure a reliable coating.

3. Solder Bath Dipping

The PCB is then dipped into a bath of molten solder. For lead-free HASL, the solder typically consists of a tin-silver-copper (SAC) alloy, which is heated to a temperature between 240°C and 260°C (464°F to 500°F). The molten solder covers the entire surface of the PCB, including the copper pads and through-holes, forming a protective layer.

4. Hot Air Leveling

Once the PCB is removed from the solder bath, it immediately undergoes the leveling process. The board is passed through a pair of hot air knives positioned on either side. These knives blow high-pressure, heated air across the surface of the PCB, removing any excess solder and ensuring a uniform layer remains on the pads.

5. Cooling

After leveling, the PCB is cooled to solidify the solder coating. This cooling is typically done using an air or water-based cooling system, depending on the specific requirements of the manufacturing process. Rapid cooling can sometimes introduce stresses into the solder layer, so the cooling rate must be carefully controlled to avoid defects like cracking or warping.

6. Post-Process Cleaning

In some cases, the PCB may undergo a final cleaning step to remove any flux residues or other contaminants that might remain after the HASL process. And then testing and inspection.

What Is the Difference Between HASL and ENIG Finish?

While both HASL and ENIG are popular PCB surface finishes, they differ significantly in their composition, application, and performance:

Characteristic	HASL	ENIG
Cost	Lower cost, suitable for budget-sensitive projects	Higher cost, but justifiable for high-reliability needs
Solderability	Excellent, but may vary with coating thickness	Consistent, even for fine-pitch components
Durability	Reasonable, but less effective in harsh environments	Superior, with excellent corrosion resistance
Thermal Performance	Good, but uneven surface might cause issues	Excellent, with consistent performance in high-heat scenarios
Best Suited For	General-purpose electronics, consumer products	High-reliability applications, aerospace, medical, and high-density PCBs
Surface Flatness	May have uneven surface, less ideal for fine-pitch components	Extremely flat surface, ideal for precise component placement
Environmental Impact	Lead-free HASL is environmentally safer, but traditional HASL uses lead which is harmful	Environmentally friendly, as it doesn’t use lead or other harmful materials
Shelf Life	Shorter shelf life due to potential oxidation over time	Longer shelf life due to gold’s resistance to oxidation
Reworkability	Easier to rework due to the nature of solder	More challenging to rework due to hard nickel layer

HAL vs. HASL

HAL (Hot Air Leveling) and HASL (Hot Air Solder Leveling) are terms often used interchangeably, but they can refer to slightly different processes. HAL is a broader term that encompasses any method of leveling solder using hot air. In contrast, HASL specifically refers to using solder to coat the PCB’s surface. Essentially, all HASL processes are HAL, but not all HAL processes are HASL.

What Is the Composition of HASL?

At present, the solder of lead-free solder alloy hot air leveling is mainly Sn-Cu-Ni+Ge (germanium) or Sn-Cu-Ni+Co (cobalt). The components of Sn-Cu-Ni+Ge (Germanium) in the OPA2544T are Sn, 0.7% Cu, 0.05% Ni and Ge with a nominal content of 65×10-6. Germanium can not only prevent the growth of oxides, but also prevent the solder joints on the PCB pad coating surface from yellowing and tarnishing during the HASL process and subsequent reflow welding and wave soldering processes. In addition, germanium can also inhibit the formation of slag in lead-free wave soldering.

The biggest problem in the lead-free HASL process is the problem of sinking copper in the tin tank during the use of the equipment.

The typical operating temperature range of the HASL process is 265 to 275 ° C, and this temperature range can be used for almost all actual manufactured laminates. At this temperature, even CEM1, there is no problem of delamination and degradation. However, the actual process temperature increases with the increase of copper composition in the tin tank. When the copper composition is 0.3% higher than the optimal value of 1.2%, then the welding temperature must be increased to 285 ° C, which is not the laminate can withstand. Although a copper-free solder alloy can be added to reduce the copper content in the tin tank, it is difficult to control the proportion.

The so-called “freeze-drying” method can also be used. When the tin lead eutectic solder (63Sn-37Pb) temperature drops to about 190℃, the melting tin copper intermetallic compound (Cri6Sn5) will be “freeze-dried”. In high-density lead solders, Cu6Sn5 floats on the surface of the molten solder and can be skimmed out using a slotted spoon. However, in lead-free solder, Ct16SIl5 is denser than lead-free solder, and CLJ6Sn5 will settle to the bottom of the tin tank. There is a mechanism to reduce the temperature to about 235 ° C (about 8 ° C higher than the melting point temperature), the tin tank shut down for at least two hours, preferably all night, at this time, most of the alloy is still in a molten state, you can design special tools, from the bottom of the tin tank out of the precipitation of Cr16Sn5, but it is still very difficult.

What Is the Minimum Pitch for HASL?

The minimum pitch for HASL refers to the smallest distance between two adjacent pads that can be reliably soldered using the HASL process. Due to the nature of the hot air leveling process, which can create uneven surfaces, HASL is generally not recommended for very fine-pitch components. The minimum pitch is typically around 0.65mm, but it can vary depending on the specific requirements and the quality of the HASL process used.

Does HASL Oxidize?

One of the main concerns with any PCB finish is oxidation, which can affect solderability and reliability. While HASL provides a protective solder layer that helps prevent oxidation, it is not entirely immune. Over time, especially in harsh environments, the solder can oxidize, leading to potential issues during assembly. However, proper storage and handling can minimize this risk, making HASL a reliable choice for many applications.

How Thick Is the HASL Coating?

The thickness of the HASL coating can vary depending on the process parameters and the type of solder used. Typically, the thickness ranges from 1 to 25 microns. This variability can be a drawback for applications requiring precise and consistent thickness, especially for fine-pitch components. However, for many general-purpose applications, the thickness provided by HASL is more than sufficient.

What Is the Black Pad Syndrome?

Black pad syndrome is a phenomenon associated with the ENIG finish, not HASL. It occurs when there is an issue with the nickel layer during the ENIG process, leading to poor solder joints and potential failures. The term “black pad” refers to the appearance of the affected nickel layer, which turns black due to oxidation and contamination. While this issue is unrelated to HASL, it’s important to note that HASL does not suffer from black pad syndrome, making it a more straightforward and reliable finish in this regard.

When choosing between lead-free HASL and ENIG surface finishes for your PCB, it’s important to consider the specific needs of your project. For reliable and high-quality PCB manufacturer, consider working with Best Technology, a leader in the field. With our expertise and advanced technology, we ensure that your PCBs meet the highest standards of quality and performance. Whether you choose HASL or ENIG, we have the experience and capability to deliver the best results for your project.

Tags: hasl, hasl pcb
Posted in best pcb, bestpcb, FAQ, FR4 PCB, PCB News, PCB Technology | No Comments »