PCB wiring principles are as follows
(1) input and output conductors should be used to avoid adjacent parallel. The best line between the line, in order to avoid feedback coupling.
(2) The minimum width of the printed wire is mainly determined by the adhesion strength between the conductor and the insulating substrate and the current value flowing through them. When the thickness of the copper foil is 0.05mm and the width is 1 ~ 15mm. Through the 2A current, the temperature is not higher than 3 ℃, so the wire width of 1.5mm (60mil) to meet the requirements. For integrated circuits, especially digital circuits, usually choose 0.02 ~ 0.3mm (0.8 ~ 12mil) wire width. Of course, as long as allowed, or as far as possible with wide lines. Especially the power cord and ground. The minimum spacing of the wires is mainly determined by the worst case insulation resistance and breakdown voltage. For integrated circuits, especially digital circuits, as long as the process allows, can make the pitch as small as 5 ~ 8mm.
(3) printed wire bend generally take a circular arc, and the right angle or angle in the high-frequency circuit will affect the electrical performance. In addition, try to avoid using a large area of copper foil, otherwise. Long time heat, easy to occur copper foil expansion and shedding phenomenon. It is necessary to use a large area of copper foil, it is best to use a grid-like. This will help eliminate the copper foil and the substrate between the heat generated by the volatile gas.
(4) pad: pad center hole than the device lead diameter slightly larger. The pad is too easy to form a weld. The outer diameter D of the pad is generally not less than (d + 1.2) mm, where d is the lead diameter. For high-density digital circuits, the minimum diameter of the pad is desirable (d + 1.0) mm