The PCB board is the basic electronic component of all electronic circuit design, and as the main support, it carries all the components that make up the circuit. The role of the PCB is not only to combine the scattered components, but also to ensure the regularity of the circuit design, and to avoid the confusion and error caused by the manual cable and wiring.
This paper gives a detailed introduction to the five key design points of the PCB circuit board.
1. Have a reasonable orientation
Such as input / output, AC / DC, strong / weak signals, high frequency / low frequency, high voltage / low voltage. Their orientation should be linear (or separate) and should not be intertwined. Its purpose is to prevent mutual interference.
The best orientation is in a straight line, but it is generally difficult to achieve. The most unfavorable orientation is the ring, fortunately, set isolation can to improve. For DC, small signal, low voltage PCB design requirements can be lower. So "reasonable" is relative.
2. Choose a good grounding point
The grounding point is often the most important A little grounding point doesn't know how many engineers and technicians have discussed it, which shows its importance. In general, it is required to share the grounding point. For example, multiple ground wires of the forward amplifier should be connected and then connected to the main line.
In reality, it is difficult to do it completely because of various restrictions, but you should try to follow it. This problem is quite flexible in practice. Everyone has their own set of solutions.
3. Reasonably arrange power supply filter and decoupling capacitor
Generally, only drawn some power supply filtering and decoupling capacitors in the schematic diagram, but it is not indicated where they should be connected. In fact, these capacitors are set for switching devices or other components that require filtering or decoupling. These capacitors should be placed as close as possible to these components, and it would be ineffective if they are too far apart. Interestingly, the grounding point problem is less noticeable when the power supply filtering and decoupling capacitors are properly arranged.
4. The line diameter is required, the buried hole and through hole should be appropriate size
Have condition to do wide lines never make it thin, high-voltage and high-frequency lines should be smooth, no sharp chamfers, and turning corners should not use right angles. The ground wire should be as wide as possible, and it is best to use a large area of copper, which has a considerable improvement on the grounding point problem. The wire is too thin, and the large area of the unwiring area is not provided with copper, which is likely to cause uneven corrosion. That is, when the unwiring area is corroded, the thin wire is likely to corrode too much, or it may be broken or completely broken. Therefore, the role of setting copper is not only to increase the ground area and anti-interference.
The buried hole and through hole should be appropriate size. If the pad or hole size is too small, is not good for drilling, if the pad size is not properly matched to the hole size, it is easy to drill the pad into a "c" shape and then drill the pad.
5. The number of vias solder joints and line density
Some problems are not easy to find in the early stage of circuit production, they tend to emerge in the later stage. For example, there are too many vias, and the copper plating process will cause hidden dangers. Therefore, the design should minimize the number of vias.
Straight lines in the same direction are too dense, and it is easy to form a piece when welding. Therefore, the linear density should be determined by the level of the welding process. The distance between the solder joints is too small, which is not conducive to manual soldering, and can only solve the welding quality by reducing the work efficiency.
Otherwise it will leave hidden dangers. Therefore, the determination of the minimum distance of the solder joint should take into account the quality and work efficiency of the welding personnel.
If you can fully understand and master the above PCB board design considerations, you can greatly improve the design efficiency and product quality. Correcting existing errors during production will save a lot of time and cost, and save rework time and material investment.
