First, PCB layout design should follow the principle:
First of all, to consider the size of the PCB. When the PCB size is too large, the printed lines are long, the impedance increases, the anti-noise ability drops and the cost increases; too small, the heat dissipation is not good, and the adjacent lines are susceptible to interference. After determining the size of the printed circuit board, determine the position of the special component. Finally, according to the function unit of the circuit, all components of the circuit are laid out.
Observe the following guidelines when determining the location of special components:
1, as far as possible to shorten the connection between high-frequency components, try to reduce their distribution parameters and the electromagnetic interference between each other. Easily disturbed components can not be too close to each other, input and output components should be as far as possible.
2, some components or wires may have a high potential difference between them, should increase the distance between them, so as to avoid accidental short-circuit discharge. With high voltage components should be as far as possible in the commissioning when the hand difficult to touch the place.
3, the weight of more than 15g components, should be fixed with a bracket, and then welding. Those big and heavy, a lot of heat of the components, should not be installed on the printed board, but should be installed in the machine bottom plate, and should consider the heat dissipation problem. Thermal components shall be kept away from the heating elements.
4, for the potentiometer, adjustable inductance coil, variable capacitor, micro-switch, such as the layout of adjustable elements should consider the structural requirements of the whole machine. If the adjustment in the machine, should be placed on the printed board to facilitate the adjustment of the place, if the machine outside the adjustment, the position and adjust the knob in the chassis panel position.
5. The position of the PCB locating hole and the fixing bracket should be left out.