Dendritic growth observed on MIL-I-46058 “Y-Pattern” test board while applying 7 VDC.
SIR testing is performed to determine whether the materials used in an assembly are likely to produce unacceptable current leakage levels, or shorts due to metal migration between conductors. This metal migration is best described as a reverse plating of the copper or tin-lead conductors in the presence of ions, water, and an electrical potential.
What does this mean in terms of the final product? Metal migration between isolated conductors on a completed assembly may produce electrical shorts. In simple terms, shorts occur when the space between the conductors is bridged by dendrites formed by re-deposited metal ions. This occurrence spells FAILURE.
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