Quality Assessment

In striving to produce higher yields and fault‐free printed wiring assemblies, the PWB processor usually finds solder shorting or bridging to be one of the most difficult faults to eliminate. Finding himself faced with a high incidence of solder bridging, he usually attacks the problem by examining his own process parameters. Fluxing, preheating, solder composition and temperature, conveyor speeds, etc., are all assessed and adjusted so that the problem is minimised as much as possible. But still it appears, though at a lower level of incidence (l‐3%). With nothing else in his arsenal of weapons to attack this persistent problem, the process engineer is left somewhat helpless, wondering what further he can do to aid his course.