The reason and countermeasure of insufficient solder for crest solder joint

The lack of solder in the crest solder joint means that the solder joint is shriveled, the solder joint is incomplete with holes (blow holes, pinholes), the solder is not full in the cartridge holes and through holes, or the solder does not climb to the plate of the component surface.

1. PCB preheating and welding temperature is too high, so that the viscosity of the molten solder is too low. Preventive measures: the preheating temperature is 90-130 ℃, and the upper limit of preheating temperature is taken when there are more mounted components; Solder wave temperature is 250±5℃, welding time is 3~5s;
2. The aperture of the insertion hole is too large, and the solder flows out of the hole. Preventive measures: The aperture of the insertion hole is 0.15~0.4mm straight than the pin (the lower limit is taken for the thin lead, the upper limit is taken for the thick lead);
3. Insert the component fine lead large pad, the solder is pulled to the pad, so that the solder joint is shriveled. Preventive measures: the size of the pad and the diameter of the pin should match, which should be conducive to the formation of the meniscus solder joint.
4. Poor quality of metallized holes or flux resistance flowing into holes. Preventive measures: reflect to the printed board processing plant, improve the processing quality;
5. The crest height is not enough. Cannot make the printed board produce pressure on the solder wave, which is not conducive to tinning. Preventive measures: the peak height is generally controlled at 2/3 of the thickness of the printed board;
6. The printed board climbing Angle is small, is not conducive to flux exhaust. Preventive measures: The climbing Angle of the printed board is 3-7°.