Refers to a series of basic requirements for the installation of the board into the chassis, the enclosure, and the slot in a specific application without causing interference such as space interference or short circuit, and placing the specified connector in a specified position on the chassis or the casing. Claim. I won't go into details here.
The board should be able to withstand the various external forces and vibrations encountered during installation and operation. For this reason, the circuit board should have a reasonable shape, and the positions of various holes (screw holes, shaped holes) on the board should be reasonably arranged. Generally, the distance between the hole and the edge of the plate is at least greater than the diameter of the hole. At the same time, it should be noted that the weakest section of the plate caused by the shaped hole should also have sufficient bending strength. The connectors that directly "stretch" out the device casing on the board must be reasonably fixed to ensure the reliability of long-term use.
3. Being heated
For high-power, severely heated devices, besides ensuring heat dissipation conditions, be careful to place them in the proper position. Especially in precision analog systems, special attention should be paid to the adverse effects of the temperature field generated by these devices on the fragile preamplifier circuit. Generally, the part with very large power should be made into a single module and take certain thermal isolation measures from the signal processing circuit.
Signal interference The most important factor to consider in PCB layout design. The most basic aspects are: weak signal circuit and strong signal circuit are separated or even isolated; AC part is separated from DC part; high frequency part is separated from low frequency part; pay attention to the direction of signal line; ground line arrangement; proper shielding and filtering And other measures. These are a lot of arguments that have been repeatedly emphasized and will not be repeated here.
Not only must we consider the neat and orderly placement of components, but also consider the graceful and smooth routing. Since the average layman sometimes emphasizes the former, to evaluate the advantages and disadvantages of the circuit design one-sidedly, for the image of the product, the former should be given priority when the performance requirements are not critical. However, in high-performance applications, if you have to use a double-panel, and the board is also packaged inside, you can't usually see it, you should give priority to the aesthetics of the trace. The next section will discuss the "aesthetics" of wiring.