PCB circuit board drawing experience

- Mar 25, 2017-

PCB design requirements

This is the most basic and most important requirement for the design of the printed circuit board, which can realize the connection of the electrical schematic diagram and avoid two simple and fatal errors. The basic requirements to achieve in the design manual and simple CAD software design in PCB is not easy, the products have to go through more rounds of trial modifications, the powerful CAD software has a test function, can guarantee the correctness of the electrical connection.

This is a higher level of PCB design requirements. Connect the circuit board right may not be good reliability, such as material selection is not reasonable, the thickness of the plate and the fixed component layout is not correct, may lead to improper PCB not work reliably, early failure even cannot work correctly. Another example of multi board and single, double-sided board, compared to the design is much easier, but in terms of reliability is not as good as single, double-sided board. From the reliability point of view, the simpler the structure, the smaller the use of the surface, the less the number of boards, the higher the reliability.

This is a deeper level of PCB design, more difficult to meet the requirements. A printed circuit board, printed circuit board from the manufacturing, inspection, assembly, debugging, assembly, commissioning, maintenance until all with PCB design are closely linked, for example, the board shape well processing difficulties, so small lead assembly is difficult, the pilot did not leave highly difficult, improper choice of connection plate maintenance difficulty. Every difficulty can lead to increased costs and extended hours. Each of the causes of the difficulty stems from the designer's mistakes. There is no absolute rational design, only the process of rationalization. It requires the designer's sense of responsibility and rigorous style, as well as experience in the practice of summary and improvement.

It is not difficult to achieve, but not easy to achieve, but must achieve the goal. Say "not difficult", the board selection of low price, board size as small as possible, the connection with direct welding wire, surface coating with the cheapest, choose the lowest price processing factory, etc., printed board manufacturing prices will drop. But do not forget that these cheap choices may cause manufacturability, poor reliability, manufacturing costs, maintenance costs rise, the overall economy is not necessarily a branch, it is not easy". "Must" is the principle of market competition. Competition is relentless, an advanced principle, high-tech products may die due to economic reasons.

Two, PCB wiring principle

In the PCB design, wiring is an important step of product design, it can be said in front of the preparatory work is done for it, in the whole PCB, wiring design process maximum limit, the maximum workload, fine skills. PCB wiring has one side wiring, double side wiring and multilayer wiring. There are two kinds of methods: automatic wiring wiring and interactive wiring, in the automatic wiring before, to more stringent requirements for interactive pre wiring line, input and output lines should be avoided so as to avoid the interference of adjacent parallel. When necessary, the grounding wire should be isolated, and the wiring of the two adjacent layers should be perpendicular to each other.

Automatic routing rate, depends on good layout, wiring rules can be set in advance, including the number of bends, wire guide hole number, step number etc.. General exploration of the first cloth warp, quickly connected to the short circuit, and then the maze of wiring, the first cloth to the wiring of the global routing optimization, it can be broken down according to the needs of the cloth line. And try to re wiring, in order to improve the overall effect.

The PCB design of high density has been felt through holes do not adapt, it wasted a lot of valuable routing channel, in order to solve this problem, the blind and buried hole technology, it not only completed the conduction hole, but also many province wiring channel makes the wiring process more convenient. More smooth, more perfect, the design process of PCB plate is a complex and simple process, want to have a good grasp of it, also need a large number of electronic engineering design personnel to their own experience, in order to get the true meaning.

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