In PCB proofing, what are the design requirements for PCB printed circuit boards? Let's take a look:
1. Accurate
This is the most basic and important requirement for printed board design. Accurately realize the connection relationship of the electrical schematic diagram to avoid errors of "short circuit" and "open circuit". General products have to go through more than two rounds of trial production and modification, and the CAD software with strong functions has the inspection function, which can ensure the correctness of the
electrical connection.
2. Reliable
Correctly connected circuit boards do not necessarily have good reliability. For example, unreasonable selection of boards, incorrect board thickness and installation, and improper layout and wiring of components may cause the PCB to not work reliably.
3. Reasonable
A printed board assembly, from manufacturing, inspection, assembly, debugging to complete machine assembly, debugging, until use and maintenance, is closely related to the rationality of the printed board; if the shape of the board is not well selecte, it is difficult to process, and the lead hole is too small Difficulties in assembly and difficulty in leaving no pilot height may lead to increased costs and extended working hours. It requires the designer's sense of responsibility and rigorous style, as well as the experience of continuous summarization and improvement in practice.
4. Economy
If the board is selecte at a low price, the size of the board should be as small as possible, direct soldering wires are used for connection, and the cheapest surface technology is used, the manufacturing price will drop. However, these cheap options may cause poor manufacturability and reliability, and increase manufacturing costs and maintenance costs.
solution:
(1) There must be a reasonable direction: such as input/output, AC/DC, strong/weak signal, high frequency/low frequency, high voltage/low voltage, etc., their direction should be linear (or separated), and must not blend with each other. Its purpose is to prevent mutual interference.
(2) Choose a good grounding point: For example, the multiple ground wires of the forward amplifier should be merged and then connected to the main line ground, etc.
(3) Reasonably arrange the power filter/decoupling capacitors: Generally, only a few power filter/decoupling capacitors are drawn 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/decoupling, and these capacitors should be arranged as close as possible to these components.
(4) Pay attention to the lines: if possible, the wide lines should never be thin; the high-voltage and high-frequency lines should be smooth, without sharp chamfers, and corners should not be at right angles. The ground wire should be as wide as possible, and it is best to use a large area of copper.
(5) Although some problems occurred in the post-production, they were brought about by the PCB design. They are: too many wire holes, and a little careless copper sinking process will bury hidden dangers. Therefore, the design should minimize the number of holes. The density of parallel lines in the same direction is too high, and it is easy to connect together when welding. Therefore, the linear density should be determined according to the level of the welding process.
