Pcb assembly reflow soldering process requires that the pads of both chip components should be independent pads. When the pad is connected to a large-area ground wire, the cross-laying method and the 45 ° -laying method should be preferred; the wire drawn from the large-area ground wire or the power line should be longer than 0.5mm and wider than 0.4mm; The wire connected to the pad should be led out from the center of the long side of the pad to avoid a certain angle. See figure (a)
The wires between the SMD pads and the lead wires from the pads are shown in Figure (b). The picture shows the connection diagram of the pad and the printed wire
The trend and shape of the printed wire
(1) The printed wire of the circuit board in PCB assembly should be very short, so if you can do the shortest, do not go complicated, follow the rules: simple and short rather than complicate and long. It is very helpful for the quality control of the PCB circuit board in the later period.
(2) The direction of the printed wires must not have sharp bends and acute angles, and the angle of the printed wires must not be less than 90 °. This is because it is difficult to corrode small inner corners when making the board. At the outer corner that is too sharp, the copper foil is easily peeled off or warped. The best form of turning is a gentle transition, that is, the inside and outside corners are the best radians.
(3) When the wires pass between the two gaskets without conecting with them, they should be kept at the maximum and equal distance; similarly, the distance between the wires should be uniform and equal, and be kept at the maximum.
(4) When connecting wires between PCB pads, when the center distance between pads is less than the outer diameter D of the pad, the width of the wire can be the same as the diameter of the pad; When it is greater than D, the width of the wire should be reduced. When there are more than 3 pads on the pad, the distance between the wires should be greater than 2D.
(5) Copper foil should be reserved as much as possible for ordinary grounding wires.
(6) In order to increase the peeling strength of the gasket, a production line with no conductive effect can be provided.
When many customers make products for the first time, he didn’t know very much. When they came, they asked you if this is Shenzhen FASTPCBA Electronics Co., Ltd.? I have pictures on this board. And always say that you can follow my PCB circuit board and do exactly the same as in my photos, but PCB design is a very complicated knowledge, such as pads, wires, and laying.
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