The connector manufacturer submitted two connectors
that exhibited solderability problems These connectors were 50-pin
D-connectors used by the military (Figure 1
). The terminals were made of a bronze (copper-tin alloy) base material with a nickel electroplate. After the terminals were electroplated, they were stored and shipped. Once received, they were tinned in a 60-40 (60% tin, 40% lead) solder bath, steam aged, and solderability tested using MIL-STD-202, Method 208.
The MIL-STD-202, Method 208, solderability test requires dipping the components in a rosin (R) flux and then tinning them with a 60-40 tin-lead solder. After the tinning process, the terminals were inspected for any appearance of nonwetting. The terminals of the connectors were exhibiting areas of nonwetting and, therefore, failing the solderability test.