PCB design requirements

1. Correct This is the most basic and important requirement for the PCB design. The connection between the electrical schematics is accurately implemented, and simple and fatal errors such as “short circuit” and “breaking” are avoided. This basic requirement is not easy to do in the manual design and PCB design using simple CAD software. Generally, more products have to undergo two or more trial modifications. The more powerful CAD software has the inspection function, which can ensure the electrical connection. The correctness.

2. Reliable This is the higher level requirement in PCB design. The connection of the correct circuit board may not be reliable, for example, the unreasonable selection of the plate, the incorrect plate thickness and mounting and fixing, improper layout and wiring of the components may cause the PCB to fail to work reliably, and the early failure may not even work properly. Another example is that multi-layer boards are much easier to design than single and double-sided boards, but they are not as reliable as single and dual boards in terms of reliability. From the perspective of reliability, the simpler the structure, the smaller the use, the fewer the number of board layers, and the higher the reliability.

3, reasonable This is a deeper layer in the PCB design, more difficult to meet the requirements. A printed board assembly, from the manufacture, inspection, assembly, debugging of the printed board to the assembly and debugging of the whole machine, to the use and maintenance, are all closely related to the reasonableness of the printed board, such as the difficulty in selecting the board shape and processing difficulties. The lead hole is too small to assemble, it is difficult to leave the pilot point, the connection of the board is not properly maintained and difficult to repair. Every difficulty may lead to increased costs and longer working hours. Every cause of difficulty is caused by the designer's mistake. There is no absolute rational design, only a constant rationalization process. It requires the designer's responsibility and rigorous style of work, as well as the experience of breaking down and improving in practice.

4. Economy This is a goal that is not difficult to reach and difficult to achieve but must be achieved. Saying "is not difficult", low prices for board selection, board size as small as possible, straight soldered wires for connection, cheapest coating for surface coating, lowest-cost processing plant, etc., will reduce the manufacturing cost of printed boards. But don't forget that these cheap choices may cause procedural problems, deteriorate reliability, increase manufacturing costs and maintenance costs, and do not necessarily separate the overall economy. Therefore, it is said that it is not easy. "Must" is the principle of market competition. Competition is ruthless. An advanced technology and high-tech products may be premature due to economic reasons.

No device installation size
P123
Printed circuit
1 Printed conductor width Printed conductor Average resistance No. Test conditions Resistance (W/m)
1 Normal condition 0.306
2 Temperature 40°C, Relative Temperature 95, 48h 0.326
3 Temperature -60°C, 10h 0.196
4 Temperature 50°C, 10h 0.341
5 Temperature 100°C, 2h 0.385
Note: The wire is 1.5mm wide and 50um thick.
Maximum permissible operating current for conductors Width (mm) 1 1.5 2 2.5 3 3.5 4
Wire area (mm2) 0.005 0.075 0.1 0.125 0.15 0.175 0.2
Conductor current (A) 1 1.5 2 2.5 3 3.5 4



Source: Network