Humidity Threshold Variations for Dendrite Growth on Hybrid Substrates

The investigation of black-box failures, which occurred during operational temperature cycling, revealed that the failures were caused by a dendritic like growth of gold between metallization paths on hybrid micro-circuit substrates. The hybrids had successfully passed the level B screening tests required by MIL-STD-883. Subsequent investigation revealed that tests to determine the presence of water vapor in the hybrid packages could not consistently detect parts which contained dendrites. This fact led to the initiation of a series of tests designed to determine and quantify the levels of moisture and/or contamination required to promote the growth of dendrites.