Do you know how to prevent ESD in PCB layout?

PCB proofing refers to the trial production of printed circuit boards before mass production. It is mainly used for electronic engineers to design circuits and complete the process of drawing PCBs before conducting small batch trial production to circuit board factories, which is PCB proofing. The following is an introduction to what preparations need to be done before PCB proofing.

There are simple PCB boards and some complex ones. It goes without saying that it is easy to proof a simple PCB board, but if it is a complex circuit board, you need to be cautious. If you do not use relevant testing tools during the PCB proofing process, in case something goes wrong, It will be too late when the PCB board is ready. Therefore, sufficient preparations must be made before proofing.

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Preparations required before PCB proofing

1. Physical border production

The closed physical frame is a basic platform for future component layout and PCB proofing. We must pay attention to accuracy. Furthermore, it is best to use arcs at the corners, which not only avoids scratches by sharp corners, but also reduces stress. .

2. Introduce components and networks, and layout the components

When introducing components and networks into the drawn borders during PCB proofing, be sure to follow the prompts carefully, including the packaging form of components and component network issues. Because of the control prompts, problems are less likely to occur. The layout of components and wiring during PCB prototyping have a great impact on the product’s life, stability, and electromagnetic compatibility, and should be paid special attention to. Generally speaking, there should be the following principles: placement order and attention to heat dissipation.

3. PCB design, wiring and adjustment

When designing and wiring PCB, it is best to pay attention to the processing parameter requirements, or go to a trustworthy PCB proofing manufacturer, and the defective rate will be greatly reduced. After completing the PCB design and wiring, all you need to do is to make some adjustments to the text, individual components, and wiring, and apply copper (this work should not be done too early, otherwise it will affect the speed and cause trouble to the PCB design and wiring). The same is for Convenient for production, debugging and maintenance.

4. Check and verify the network

Sometimes due to misoperation or negligence, the network relationship of the drawn PCB board is different from the schematic diagram. In this case, inspection and verification are necessary. Therefore, after drawing, you should check it first before proceeding with follow-up work.

Materials required for PCBA proofing
Before starting the PCBA prototyping process, you must prepare some necessary materials and tools. The following are the materials and tools required for proofing:
– PCB board (bare board)
– Components
-Steel mesh
– SMT machine
– Welding machine
-Soldering iron
All these materials and tools must be of high quality to ensure the quality of the PCBA.

Steps of PCBA prototyping process

The following are the detailed steps of the PCBA proofing process:

First: Plan the PCB board and generate Gerber files. The Gerber file is then sent to the PCB manufacturer to produce the bare board.
Step 2: Purchase all required components. All components must meet design specifications and must be reliable.
Step 3: Paste the components onto the PCB board through the steel mesh.
Step 4: Use the placement machine to accurately place all components on the PCB board. During this process, be sure to pay attention to whether all components are correctly attached. Also check whether all components are in the correct position and whether there are any unusual errors.
Step 5: Use equipment for welding. Solder component pins manually by using a soldering iron.
Step 6: Hot dip solder or wave solder the components through the welding machine.
Step 7: Conduct electrical testing. Domit or other electrical testing tools can be used to test and ensure the PCBA is functioning correctly.
Step 8: Conduct functional testing. Run the PCBA to ensure it functions as expected.

Precautions for PCBA prototyping process

In order to ensure the success of the PCBA prototyping process, here are some things to pay attention to:
– Choose high-quality PCB boards and components to ensure product quality.
– Precisely plan the layout of the circuit board.
– Ensure that the fitting process of components on the PCB board is completed accurately.
– Make sure to use high-quality placement machines and welding machines for the fitting and welding process of components.
– Make sure the PCBA orientation is accurate and in good contact.
– Before performing electrical testing, confirm that components are installed correctly and require functional testing.
In short, PCBA prototyping is a very important step in circuit board manufacturing. The quality of proofing affects the quality of the entire product. Ensure that PCBA proofing is carried out according to the correct process to provide guarantee for product quality.

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Methods to shorten PCBA prototyping time

One method: collaborative design, early intervention
In the production process of electronic components, operations such as schematic diagram, PCB design, and pad mapping are interconnected and influence each other. Therefore, in order to shorten the prototyping time, designers need to intervene in the design and manufacturing process as early as possible and actively collaborate with various departments.
During the design process, some unreasonable designs may lead to repeated proofing, thereby prolonging development time. To avoid this situation, designers should communicate and coordinate with PCB design engineers and pad mapping engineers before the design starts, during the design, and finally at the end of the design. This helps teamwork, saves time and energy, and shortens proofing time.

The second method: full process management
In the entire PCBA prototyping process, full-process management is very important, and it is usually the responsibility of the engineer responsible for management. During the implementation process, managers should formulate and implement full-process management specifications according to the manual. Management practices should include raw materials, manufacturing process management and quality control.
From the perspective of raw materials, review the qualifications and production quality of raw material manufacturers, check whether raw materials meet quality requirements, and ensure the stability and reliability of raw materials. From the perspective of manufacturing process management, advanced, stable and efficient production processes must be strictly implemented. At the same time, we also need to adapt our organization to the complexity of our products and manufacturing processes. From the perspective of quality control, different manufacturing links need to be accurately monitored according to different stages to check the stability of the manufacturing process and ensure the quality of finished materials.

The third method: Choose a reliable PCB Service platform

Choosing a reliable, practical and efficient PCB Service platform is also the key to shortening PCBA prototyping time. A good PCB Service platform can save valuable time and money for electronic engineers and manufacturers, and assist users to create viable products at the appropriate time. Choose the PCB Service platform that suits you and customize it according to the company’s actual situation, which can shorten the proofing cycle and reduce production and manufacturing costs.
An efficient PCB Service platform, in addition to providing high-quality products and services, also needs to be convenient so that operators can easily handle various arrangements for PCBA proofing in their systems. This reduces errors in the production line and avoids re-making, further reducing costs and improving production efficiency.
In short, shortening PCBA prototyping time is a long-term, iterative, and complex process. The above three methods can all help you shorten PCBA prototyping time from different angles, and can complement each other in practice, while improving production efficiency, quality, and requested completion time. Let us always maintain a sense of innovation and keep moving forward in the continuous search for ways to improve production efficiency and quality.

Issues that should be paid attention to when using components for PCBA proofing

1. Limiting the output current can avoid the locking effect of CMOS circuits.

The lock-in effect means that there are parasitic PNP transistors and NPN transistors in the internal structure of the CMOS circuit, and they happen to form a parasitic PNPN thyristor structure. This interlocked positive feedback structure may be triggered by external factors (such as electrostatic discharge), and a current will flow through the PNP tube (or NPN tube), and then pass through another parasitic NPN tube (or PNP tube) to cause the current to flow. Amplified, and due to the positive feedback effect, the current becomes larger and larger and eventually burns out. It can be seen that limiting the current so that it cannot reach a level that maintains the locked state is one of the issues to be considered for CMOS devices when PCBA prototyping.
A common solution is to use a resistor to isolate each output from its cable, and use two high-speed switching diodes to clamp the cable to VDD (drain supply) and VSS (source supply). .

2. Use filter network

Long input cables are sometimes required between the CMOS circuit system and the mechanical contacts. This increases the possibility of electromagnetic interference and the use of a filter network should be considered. At the same time, long input lines are inevitably accompanied by large distributed capacitance and distributed inductance, which can easily cause LC self-oscillation, causing the diode protection network to burn out. The solution is to connect a resistor in series to the input end, and its resistance can be selected according to the formula R=VDD/1mA.

3. RC network

Where feasible, using an RC network consisting of a larger value resistor and a capacitor of at least 100pF for sensitive inputs of bipolar devices can reduce the effects of electrostatic discharge.

4. Avoid leaving the input pins of CMOS devices floating

During PCBA prototyping, it is necessary to prevent the input terminals of CMOS devices that have been soldered to the circuit board from being left floating. At the same time, it should be noted that all unused redundant input leads on the CMOS device are not allowed to be left floating. This is because once the input terminal is left floating, the input potential will be in an unstable state, which will not only destroy the normal logic relationship of the circuit, but also easily cause electrostatic breakdown, external noise interference and other phenomena. The redundant input terminals should be handled separately according to the function of the circuit.

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