1. Connect the pads to the through holes. In principle, the wires between the mounting pads and the via holes should be soldered. Lack of solder mask will lead to welding defects such as less tin in solder joints, cold welding, short circuits, unsoldered joints, and tombstones.

2. The solder mask design between the pads and the solder mask pattern specifications should conform to the design of the solder terminal distribution of the specific components: if a window-type solder resist is used between the pads, the solder resist will cause the solder between the pads during soldering. In case of short circuit, the pads are designed to have independent solder resists between the pins, so there will be no short circuit between the pads during welding.

3. The size of the solder mask pattern of the components is inappropriate. The design of the solder mask pattern that is too large will “shield” each other, resulting in no solder mask, and the spacing between components is too small.

4. There are via holes under the components without solder mask, and there are no solder mask via holes under the components. The solder on the via holes after wave soldering may affect the reliability of IC welding, and may also cause short circuit of components, etc. defect.