Reliability Testing of Fluorinated Polymeric Materials (FNP) for Hybrid Encapsulation

A new class of polymeric materials synthesized from fluorinated percursors to produce network molecules of epoxies and polyurethanes has been analyzed as a hybrid encapsulation material. The fluorinated resin (C-3) synthesized at NRL consists of approximately 50% fluorine by weight, is a liquid at room temperature and can be readily cured to the solid state. For encapsulation, the surface of the hybrids or devices was primed first with a fluoroacrylate barrier film and the C-3 resin with a cycloaliphatic diamine curing agent was used for encapsulation. Utilizing test structures, a micro-thin film (Au-Al2O3) moisture sensors and Auger/SIMS analysis, the moisture penetration kinetics for the fluorinated network polymeric materials (FNP) has been determined. It was determined that the activation energy for moisture penetration remained constant from 20 to 95% relative humidity. The measured activation energy varied from 1.9 eV at 20% RH to 2.0 eV at 95% RH. Interdigitated test structures were utilized in order to study the migrative resistive short (MGRS) phenomenon in the hybrids encapsulated with the FNP material. The results shox that for a surface ionic contamination level of 1014 Na+/cm2 on the encapsulant surface, relative humidity of 95% and temperature cycle of +100°C to (¿10°C) migrative resistance shorts were not observed after 100 cycles of total duration of 4 hours per cycle. A similar test with silicone materials resulted in MGRS formation after eight cyclet. Additional tests were conducted for Cl-, S= and K+.