Microscopic cross solders on printed wiring board assemblies

During the 10-III-82 period, the Western Electric Montgomery Works began experiencing microscopic cross solders (microshorts) on numerous data set printed wiring board assemblies (circuit packs). The microshorts were generally observed on fine line circuit packs (.010" lines and spaces) after the machine soldering operation. Three conveyorized in-line assembly/soldering processes which were involved with the problem are identical, although a higher percentage of the microshorts seemed to be occurring on the circuit packs being soldered on the assembly/soldering line number two.