MC3121 Cable-to-Header Bond-Failure Study

摘要

MC3121 detonators employ a film adhesive to join polyimideclad electrical cables to ceramic detonator headers. The film adhesive, a modified acrylic, provides support for the cable-to-heat weld junctures and also acts as a dielectric medium between the junctures. Following a successful development bonding program, gross bonding failures were suddenly observed in the fabrication of the environmental/qualification lot. The affected assemblies exhibited a significantly reduced peel strength and a failure mode that was exclusively interfacial at the polyimide-adhesive interface. Normally, a mixed failure mode is observed showing some degree of polyimide delamination from the cable. This nonbonding condition was determined to arise from surface contamination on the polyimide-clade electrical cables and was eliminated by plasma cleaning techniques. A grit-blasted polyimide surface was found to be less desirable than an untreated surface, as it acts as a contaminant sponge. (ERA citation 07:005340)