Suggestion for stardard pcb design

- Jul 06, 2017-

1, to have a reasonable direction: such as input / output, AC / DC, strong / weak signal, high frequency / low frequency, high pressure / low pressure, etc., their direction should be linear (or separation), not blending each other. Its purpose is to prevent mutual interference. The best direction is to follow the line, but generally difficult to achieve, the most unfavorable direction is the ring, but fortunately can be set to bring the improvement. For DC, small signal, low voltage PCB design requirements can be lower. So "reasonable" is relative.

    2, choose a good grounding: a small grounding I do not know how many engineering and technical personnel to do it on how much discussion, which shows its importance. Under normal circumstances require a total of points, such as: forward amplifier of the ground should be merged and then connected with the trunk and so on. In reality, it is difficult to do so because of various restrictions, but should try to follow. This problem 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 rational arrangement of power supply filter / decoupling capacitors: generally only in the schematic diagram to draw a number of power supply filter / decoupling capacitors, but did not indicate where they should be connected. In fact, these capacitors are for switching devices (gate) or other components need to filter / decoupling set, the layout of these capacitors should be close to these components, too far away from no effect. Interestingly, when the power supply filter / decoupling capacitor layout is reasonable, the grounding point of the problem becomes less obvious.

    4, lines have to pay attention: the conditions do wide line never do fine; high pressure and high frequency line should be slippery, not a sharp chamfer, the corner should not be used at right angles. Ground wire should be as wide as possible, it is best to use a large area of copper, which docking point of the problem has a considerable improvement.

    5, although some problems occur in the post-production, but it is PCB design to bring them: they are too many lines, Shen copper process will be buried in a little carelessness. Therefore, the design should be minimized through the hole. Parallel to the parallel line density is too large, easy to connect into a piece of welding. Therefore, the linear density should be determined according to the level of the welding process. The distance between the solder joints is too small, is not conducive to manual welding, only to reduce the efficiency to solve the welding quality. Otherwise it will leave hidden trouble. Therefore, the determination of the minimum distance of the solder joint should take into account the quality and efficiency of the welding personnel. The size of the pad or wire hole is too small, or the pad size is not properly matched to the borehole size. The former is detrimental to manual drilling, which is detrimental to CNC drilling. Easy to drill into a "c" shape, while the drill is drilled off the pad. Wire is too small, and a large area of the non-wiring area and not set copper, easily lead to uneven corrosion. That is, when the non-wiring area after corrosion, fine wire is likely to corrosion too far, or broken off, or completely broken. Therefore, the effect of setting copper is not only to increase the ground area and anti-jamming.

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