Packaging of low cost electronic multichip module-laminate (MCM-L) assemblies for hermetic-equivalent performance in high reliability avionics applications

This paper discusses the results of comparative reliability testing of electronic MultiChip Modules (MCMs) fabricated with laminate substrates (MCM-L) and protected with various bare-die coatings. The demonstration MCMs included flip-chip and wire-bond design versions of the digital portion of a Global Positioning System (GPS) Receiver MCM and an analog MCM far use in general aviation applications. Standard encapsulants and new inorganic coatings, Dow Corning´s ChipSeal^(R) hermetic coating materials, were evaluated using environmental stress exposures for high reliability avionics applications. Full wafer probe testing was performed before and after the Supplemental ChipSeal ^(R) processing and flip-chip processing steps. ChipSeal^(R) and flip-chip processing steps were shown to cause no device yield degradation on the five different semiconductor wafer lots tested. Environmental test results demonstrated that low cost MCM-L units with bare die packaging can be designed for very robust, high reliability applications such as military and commercial avionics