5 Problems that Need Attention in Circuit Board Processing

1. First, there must be a reasonable direction.

Such as input/output, AC/DC, strong/weak signal, high frequency/low frequency, high voltage/low voltage, etc... Their directions should be linear or separate, and they cannot merge with each other. Its purpose is to prevent mutual interference. The best trend is a straight line, but it is usually not easy to achieve. The most unfavorable trend is a circle. Fortunately, isolation can be improved. For DC, small signal, low voltage PCB design requirements can be lower. So "reasonable" is relative.

2. Second, choose a good ground point: The ground point is usually the most important.

    Many engineers and technicians have discussed this small ground point, which shows its importance. Under normal circumstances, a common ground is required, such as: multiple ground wires of the forward amplifier should be combined and then connected to the main ground, etc.... In fact, due to various restrictions, it is difficult to achieve this completely, but we should do our best. This question is quite flexible in practice. Everyone has their own set of solutions. It is easy to understand if it can be explained for a specific circuit board.

3. The power filter/decoupling capacitor should also be arranged appropriately.

Generally, only multiple power supply filters/decoupling capacitors are shown in the schematic, but they are not pointed out where they should be connected. In fact, these capacitors are provided for switching devices or other components that require filtering/decoupling. These capacitors should be placed as close as possible to these components, but if they are too far apart, they will not work. Interestingly, when the power supply filter/decoupling capacitors are arranged properly, the grounding point problem suddenly becomes less obvious.

4. Moreover, the wire must be delicate, the diameter of the circuit and the size of the buried via must be appropriate.

It is recommended to make the wide wire as wide as possible. High-voltage and high-frequency cables should be smooth, without sharp chamfers, and corners should not be at right angles. The grounding wire should be as wide as possible, and it is best to use a large area of copper coating, which can greatly improve the grounding point problem. The size of the pad or via is too small, or pad size and drill size are incorrect. The former is not conducive to manual drilling, while the latter is not conducive to CNC drilling. It is easy to drill the pad into a "c" shape, and if it is more serious, you'll lose the pad. The wire is too thin, and there is no copper in a large area without wiring, which is easy to cause uneven corrosion. That is, when the non-wiring area is corroded, the thin wires may be excessively corroded, or appear to be broken or completely broken. Therefore, the role of copper coating is not only to increase the area of ground wire and anti-interference.

5. Finally, note the number of holes, solder joints, and line density.

Although some problems occur in post-production, they are caused by PCB design. These problems are: there are too many vias, and a slight mistake in the copper sinking process will bury hidden dangers. So, the design should minimize the line holes. The density of parallel lines in the same direction is too large, and it is easy to join together when welding. Therefore, the line density should be determined according to the level of the welding process. The distance between the solder joints is very small, which is not conducive to manual soldering. We can only solve welding quality by reducing work efficiency. Otherwise it will leave hidden dangers. So, the minimum distance of solder joints should be determined by comprehensive consideration of the quality and work efficiency of the welding personnel.