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The patch components of the pcb can be placed on both sides, but the discrete components are generally placed on one side. Because the welding foot of the discrete component should pass the wave soldering, that is to say: the other side of the PCB board should pass from the solder pool, if the other side is also installed with discrete components, the discrete components should pass from the solder pool. The components should be stained with solder, and the high temperature is easy to damage the components
Generally speaking, there are very few single-sided circuit boards, if the circuit board has only one side of the line, it is a single panel, and on the contrary, it is a double panel or multi-layer board
Among the components, generally only some capacitors and inductors can be attached on both sides, and other components are only one side with pins, which in turn cannot be attached to the board.