PCB circuit board is the basal electronic components in all electronic products. As the main support, it is equipped with all the devices composed the circuit. PCB role not only combines scattered element, but also ensure the rules of the circuit design,which is good to avoid the confusion and error artificial phenomenon caused by manual cables and wiring.
This paper has detailed description for 5 key design points of PCB in the design of power.
1, To have a reasonable direction
Such as input / output, AC / DC, strong / weak signal, high / low frequency, high pressure / low pressure. Their trend should be linear (or separation), and shall not interacting with each other. Its purpose is to prevent mutual interference.
The best direction is a straight line, but generally it is not easy to achieve.The most unfavorable trend is endless, but fortunately you can set isolation to bring improvement. Requirements of DC, small signal, low-voltage PCB design can be lower. Therefore, the “reasonable” is relative.
2, Choose a good ground: ground is often the most important
The small ground, I wonder how many engineers have done exposition about it,which shows its importance.Under normal circumstances,there is requirement of common point.
In reality, due to various constraints it is difficult to completely do it, but should try to follow. This problem is quite flexible in practice, everyone has their own set of solutions.The explanation for specific printed circuit board is easy to understand.
3, Rational arrangement of power supply filter / decoupling capacitors
In general,if you only just draw a number of power filtering or decoupling capacitors in schematic diagram , but can not point out where they should be connected. In fact, these capacitors are designed for switching devices or other components that need filtering or decoupling capacitors.The arrangement of these capacitors should be as close to these component parts.If they are too far, they do not work.Interestingly,when the arrangement of power filtering and decoupling capacitor is reasonable,the problem of ground is not obvious.
4, Lines have requirements,and the size of buried holes and vias is appropriate .
Lines,which have the condition to be made wide, are never made fine. High-pressure and high-frequency lines should be sleek,and should not have sharp angles and corner ,so should not use the right angles. Ground should be as wide as possible, it is best to use a large area of copper, which has great improvement for ground point. The size of PAD or thread holes is too small,or pad size and drilling size mismatch.The former is unfavorable for manual drilling,and the latter is unfavorable for CNC drilling .The pad is easy to drill into “c” shape, if redrilling, the pad easily be off.
Wire is too small, and a large area of the unwiring region is not set with copper, which is likely to cause corrosion uneven. That is when the unwiring region finish etching,fine wire is likely to corrode too far,or a non-broken off, or completely off. Therefore, the role of setting copper does not just increase ground area and immunity.
5, the solder joints of vias and wire density
Some problems at the beginning of the production of the circuit is not easy to be found. They tend to emerge in the late, for example, there are too many via line.If the plating process has any carelessness,the hidden trouble will appear. Therefore, the design should minimize the thread hole.
The density of Parallel lines is too large, it is easy to welding together.Therefore, the line density should be determined according to the level of welding process.If the solder joint is too small,it is not conducive to manual welding.Welding quality can only be resolved by reducing the efficiency,or it will leave hidden trouble.Therefore, to determine the minimum distance from the pad should consider the quality and efficiency of welding personnel.
If we can fully understand and master the above considerations of PCB design , it is possible to greatly improve the design efficiency and the pcb manufacturing quality. When in production correcting the existing errors, we will be able to save a lot of time and costs, and save rework time and material inputs.