Good solder joints should be in the equipment life cycle, its mechanical and electrical performance does not fail. Its appearance as follows:
(1) a complete and smooth and bright surface;
(2) the appropriate amount of solder and solder completely cover the welding parts of the pad and lead, the component height is moderate;
(3) good wetting; welding edge should be thinner, solder and pad surface wetting angle of 300 or less as well, the maximum does not exceed 600.
SMT processing appearance inspection content:
(1) whether the components missing;
(2) whether the wrong parts;
(3) whether the short circuit;
(4) whether the free solder; Weld causes are relatively complex.
One, Weld the judge
1. Use on-line tester special equipment for inspection.
2, visual or AOI test. When the solder joints found too little solder infiltration bad, or solder joints in the middle of a broken seam, or solder surface convex spherical, or solder and SMD is not blinded, etc., it is necessary to pay attention, even if the slight phenomenon will cause hidden dangers, Should immediately determine whether there is a batch Weld problem. Judgment is: to see if more PCB on the same location of the solder joints are problems, such as the problem is only a separate PCB, solder paste may be scratching, pin deformation and other reasons, such as in many PCB on the same location There are problems, this time is likely to be bad components or pad problems caused.