How should PCB design layout

On the premise of satisfying the circuit performance, the layout of components should also be considered in order, beautiful and convenient for testing. The mechanical size of the board and the position of the socket should also be carefully considered.

  

Reasonable component layout is the basic premise of designing high quality PCB chart. Requirements for component layout include installation, force, heating, signal and appearance.

  

1. Install

Refers to a series of basic requirements put forward for the smooth installation of the circuit board into the chassis, housing and slots in specific application situations, without space interference, short circuit and other accidents, and for the designated connector to be placed in the specified position on the chassis or housing.

 

2. Stress 

The circuit board shall be able to withstand all kinds of external forces and vibration during installation and work. Therefore, the circuit board should have a reasonable shape, and the positions of various holes (screw holes, special holes) on the board should be reasonably arranged. In general, 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 abnormal holes should also have enough bending strength. The connectors directly "protruding" from the equipment shell on the board should be fixed reasonably in particular to ensure the reliability of long-term use.

 

3. Heat 

For high-power devices with severe heat, in addition to ensuring heat dissipation conditions, attention should be paid to the proper location. Especially in sophisticated analog systems, the adverse effect of the temperature field generated by these devices on the fragile preamplifier circuit should be paid special attention. In general, the very high power part should be made into a single module, and some thermal isolation measures should be taken between it and the signal processing circuit.


4. The signal

Signal interference is the most important factor to be considered in PCB layout design. Several basic aspects are: weak signal circuit and strong signal circuit separated or even isolated; The ac part is separated from the dc part; The high frequency part is separated from the low frequency part; Note the direction of the signal line; Layout of ground wire; Appropriate shielding, filtering and other measures. These are things that have been repeated in a great deal of literature, and they will not be repeated here.

 

5. Beautiful

Not only to consider the orderly placement of components, but also to consider the beautiful smooth line. Because the general layman sometimes emphasizes the former, in order to one-sided evaluation of the advantages and disadvantages of circuit design, in order to the image of the product, when the performance requirements are not harsh to give priority to the former. However, in the case of high performance, if you have to use a double panel, and the circuit board is also encapsulated in the inside, usually invisible, should give priority to emphasize the aesthetic line.