Investigation of corrosion minimization in integrated circuit assemblies
Studies have shown that a major contributor to commercial-off-the-shelf (COTS) integrated circuits (ICs) package failures in harsh environmental conditions used for high reliability applications is the encapsulating material. In specific, the corrosion mechanism resulting from chloride ions residing within the encapsulating material, acting in conjunction with moisture and an electrical bias, to cause failures. This work serves to investigate the reduction of corrosion propagation, which leads to failures at the gold/aluminum bond pad interface on the IC. The project entailed the use various newly-formulated encapsulating compounds with reduced levels of chloride content, while maintaining consistent levels of bromides and sodium. It is the intent of this work to identify the maximum chloride ionic content allowable that results in no corrosion or very slow propagation of corrosion at the IC bond pad. While the corrosion mechanism is well understood in, this work is unique because the maximum threshold of allowable chlorides is under investigation. This study was completed to advance industry knowledge concerning the use of COTS components as direct replacements of hermetic parts used in extreme conditions.