Five requirements for reasonab
Reasonable layout of components is the basic premise of designing high quality PCB. The requirements of element layout mainly include installation, stress, heating, signal and aesthetics.
It refers to a series of basic requirements put forward in order to install the circuit board into the chassis, shell and slot smoothly, avoid space interference, short circuit and other accidents, and make the specified connector in the specified position on the chassis or shell.
The circuit board shall be able to withstand various external forces and vibrations during installation and operation. For this reason, the circuit board should have a reasonable shape, and the positions of various holes (screw holes, special-shaped holes) on the board should be arranged reasonably. Generally, the distance between the hole and the plate edge should be 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 special-shaped hole should also have enough bending strength. In particular, the connector that directly "extends" out of the equipment shell on the board should be fixed reasonably to ensure the reliability of long-term use.
For high-power and serious heating devices, in addition to ensuring the heat dissipation conditions, we should also pay attention to placing them in appropriate positions. Especially in the precise simulation system, we should pay more attention to the adverse effect of the temperature field produced by these devices on the fragile preamplifier circuit. Generally, the part with very high power should be made into a module separately, and some thermal isolation measures should be taken between the module and the signal processing circuit.
Signal interference is the most important factor to be considered in PCB layout design. Several basic aspects are: the weak signal circuit and strong signal circuit are separated or even isolated; the AC part is separated from the DC part; the high frequency part is separated from the low frequency part; attention is paid to the direction of the signal line; the layout of the ground wire; appropriate shielding and filtering measures are taken.
We should not only consider the orderly placement of components, but also consider the beautiful and smooth routing. For the image of the product, the former should be given priority when the performance requirements are not strict.
However, in high-performance occasions, if you have to use a double-sided board, and the circuit board is also packaged inside, usually invisible, you should give priority to the beauty of the wiring.
Through the above five points, I believe that many friends have clearly placed the original need to pay attention to where.