Reliability assessment of hybrid encapsulants: Fluorinated network polymeric materials and silicones

Abstract

Hybrid encapsulation materials for Navy systems consist of silicones and silicone-dispersions. Utilizing test structures, a micro-thin film AU-AI2O3 moisture sensor and Auger/SIMS analysis, the mositure penetration kinetics for silicon was determined and compared with fluorinated network polymeric materials. Reliability data relating MTF of interdigitated hybrids to moisture levels on the substrate surface has been determined for the new class of polymeric coatings under consideration. The polymeric materials have been synthesized from fluorinated percursors to produce network molecules of epoxies and polyurethanes. It was determined that the kinetics activation energy remained constant for silicones and silicone-dispersions at relative humidity levels from 20% to 95%. The actual activation enegy varied from 1.3 eV at 20% to 0.97 eV at 95%. Significant improvement in moisture penetration resistance was observed with fluorinated network polymeric coatings. Additional test structures were utilized to study the migrative resistance shorts induced by bias, moisture and ionic contamination migration through the silicones and polymers. Finally, hybrid circuits consisting of operational amplifiers, were coated with the present synthesized polymeric materials and silicone-dispersions. Results from temperature-cycling and moisture tests will be presented and compared to results obtained from silicone coated hybrids.