Liquid Metal Embrittlement of Copper Wires

Intermittent opens in hand-assembled electronic components have a number of expected causes. In this case the failure mechanism that was identified is of concern in certain industries, but is unexpected in the electronics business. Solder in solder pots and in flow solder systems is expected to become contaminated with the various metals and other materials that the solder contacts during use. In the analysis presented here, the solder was determined to be contaminated with mercury. This contaminated solder caused wires tinned in the solder to fracture due to liquid-metal embrittlement. Liquid-metal embrittlement (LME) is the reduction in metal ductility caused by contact with liquid metal.