5 golden rules of PCB design

- Sep 15, 2018-

PCB circuit board is the basic electronic component of all electronic circuit design.The function of PCB is not only to combine the scattered components, but also to guarantee the regularity of circuit design, which avoids the chaos and error caused by manual wiring and wiring.

This paper introduces five key points of PCB in power supply design.

1. Reasonable trend

Input/output, ac/dc, strong/weak signal, high/low frequency, high/low pressure, etc.Their movements should be linear (or separate) and not blend with each other.The aim is to prevent mutual interference.

The best alignment is a straight line, but generally not easy to achieve, the most unfavorable alignment is circular, fortunately isolation can be set to bring improvement.For dc, small signal, low voltage PCB design requirements can be lower.So "reasonable" is relative.

Choose a good pickup location: the pickup location is often the most important

Its importance can be seen by the number of engineers and technicians who have written about it.In general, common ground is required, such as: forward amplifier of multiple ground lines should be joined before connecting to the main line, and so on.

In reality, it is difficult to fully do because of various restrictions, but you should try to follow them.In practice, the problem is quite flexible. Everyone has his own set of solutions, which is easy to understand if the solution is specific to the circuit board.

3. Reasonably arrange power filter/decoupling capacitance

In general, only a few power filter/decoupling capacitors are shown in the schematic diagram, but it is not indicated where they should be connected.In fact, these capacitors are set for switching devices (gate circuits) or other components that need to be filtered/decoupled, and these capacitors should be arranged as close as possible to these components as far away from them as possible.Interestingly, when the power filter/decoupling capacitance is properly disposed, the problem of the connection location is less obvious.

4. It is required that the bore hole size is appropriate for the line diameter

If you can make wide lines, never thin them.High pressure and high frequency line should slide, no sharp chamfer, no right Angle.The ground should be as wide as possible, preferably with a large area of copper coating, which is a considerable improvement in the docking site.The size of the weld pad or overwire hole is too small, or the size of the weld pad and drill hole are not suitable.The former is disadvantageous to artificial drilling and the latter to numerical control drilling.It is easy to drill the pad into "c" shape, then drill off the pad.

The wire is too thin, and the large area of the unwired area is not set with copper, easy to cause corrosion uneven.That is, when the corrosion of the unwired area is finished, the thin wire is likely to be overcorroded, or not broken, or completely broken.Therefore, the function of setting copper coating is not only to increase ground area and anti-interference.

5. Number of solder joints and wire density through holes

Some problems are not easy to be discovered in the early stage of circuit making, and they often emerge in the later stage. For example, if there are too many holes in the wire, the copper sinking process can be hidden by any carelessness.Therefore, in the design should be minimized through holes.

Parallel lines are so dense that they can easily be joined together.Therefore, the line density should be determined according to the level of the welding process.The distance of welding spot is too small, which is not good for manual welding.Otherwise there will be hidden dangers.Therefore, the determination of the minimum distance of welding spot should take into account the quality and efficiency of welding personnel.

If you can fully understand and master the points for attention in PCB design, you can greatly improve the design efficiency and product quality.It will save a lot of time and cost, rework time and material input to correct errors in production.