SOLDERABILITY OF PRINTED CIRCUITS,
Abstract:
A test was developed that utilizes a test fixture which, when pressed into a solder bath, permits solder to rise through three holes in the fixture and form meniscuses. A printed wiring board test specimen is placed on the test fixture and is held a measured distance above the holes and is contacted only by the solder meniscuses. Three circular spots of solder are produced on the printed wiring test board specimen. The spots are measured diagonally to the nearest hundredth of an inch using dividers. An average value of twelve such spots made on test boards is a measure of the board solderability. Solderability, in terms of this test, is defined as a function of solder spread distance. In order to evaluate the solderability of printed wiring boards encountered in a variety of manufacturing and storage environments, it was necessary to investigate natural and artificial aging. Natural aging tests under room temperature and humidity conditions were performed on copper clad, gold 50, 100 and 150 microinch platings, and solder-plated 500 microinch platings test boards. Copper clad, gold 50, 100 and 150 microinches, solder 500 microinches and tin 500 microinches plated test boards were artificially aged in hot air at 250 F. Author