PCB circuit board is the basic electronic components of all electronic circuit design, PCB circuit board design is also a small partner must understand. The role of PCB is not only the combination of scattered components, but also to ensure the regularity of circuit design, and very good to avoid the chaos and error caused by artificial wiring and wiring.
Such as input/output, AC/DC, strong/weak signal, high/low frequency, high/low voltage, etc. They should move in a linear (or separate) direction and not blend with each other. The aim is to prevent mutual interference. The best trend is to press straight line, but come true not easily commonly, the most unfavorable trend is annular, fortunately, it is OK to set isolation to bring improvement. For DC, small-signal, low voltage PCB design requirements can be lower. So “reasonable” is relative.
I do not know how many engineers and technicians have done many discussions on the small docking point, which shows its importance. Under normal circumstances the requirement is in total point ground, be like: after the many ground lines of forwarding amplifier should confluence, connect again with the mainline ground to wait a moment. In reality, it is difficult to do completely because of various restrictions, but we should try our best to follow. This problem is quite flexible in practice, everyone has their own set of solutions, if you can explain the specific board is easy to understand.
Only a number of power filter/decoupling capacitors are usually drawn in the schematic diagram, without indicating where they should be connected. These capacitors are intended for switching devices (gates) or other components that need filtering/decoupling. They should be placed as close to these components as possible. Too far away from these components is useless. Interestingly, when the power filter/decoupling capacitors are properly arranged, the problem of the junction point becomes less obvious.
If it is possible to make a wide line, it will never be fine. High voltage and high-frequency lines should be circular slippery, no sharp chamfering, turning should not use right angles. The ground wire should be as wide as possible, preferably using a large area of copper, this docking site problem has a considerable improvement. The size of the pad or hole is too small, or the size of the pad and hole are not matched properly. The former is unfavorable to manual drilling, while the latter is unfavorable to numerical control drilling. Easy to drill the pads into “C” shape, heavy to drill off the pads. The wire is too thin, and the large area of the unwired area is not set up copper, easy to cause uneven corrosion. That is, when the wiring area after corrosion, thin wire is likely to be too much corrosion or seems to be broken, or completely broken. Therefore, the role of setting copper coating is not only to increase the ground area and anti-interference.
Some problems in the early stage of circuit production are not easy to be found, they tend to emerge in the later stage, such as too many wire holes, copper sinking process slightly careless will bury hidden dangers. Therefore, the design should be as far as possible to reduce the line hole. Lines running in the same direction are so dense that they can easily join together when welded. Therefore, the linear density should be determined according to the level of the welding process. The welding joint distance is too small, is not conducive to manual welding, can only reduce the efficiency to solve the welding quality. Otherwise, it will leave a hidden danger. Therefore, the determination of the minimum distance of solder joints should take into account the quality and efficiency of welding personnel.
If you can fully understand and master the above PCB design matters needing attention, it will be able to greatly improve the design efficiency and product quality. Correcting errors during production will save a lot of time and cost, as well as rework time and material input.
Now PCB design time is getting shorter and shorter, smaller and smaller board space, more and more high device density, extremely strict layout rules and large size of components designers
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