Analysis of Phosphorus Flame Retardant Induced Leakage Currents in IC Packages Using SQUID Microscopy

A superconducting quantum interference device (SQUID) was used to assess leakage currents between adjacent leads of an encapsulated semiconductor device. An electrically conductive path was observed in the package interior. Red phosphorus, used as flame retardant in the mold compound, was identified as the cause of the leakage current path. This paper discusses the principle of SQUID, how it was used to verify and locate the sites of the failure, and the root cause of this new leakage current failure mechanism