Thermoplastic adhesives for microwave assembly component mounting

Silver-loaded epoxy is the conventional component attach material used in microwave hybrid assemblies. Conductive thermoplastic adhesives offer several significant advantages over epoxies for component attach including much shorter bond time and faster rework. The suitability of a silver-loaded thermoplastic adhesive for component attach is the focus of this paper. A design of experiments was conducted to identify processing conditions that maximize thermal conductivity, minimize electrical resistivity, and obtain adequate die shear strength. The loss of a transmission line on a Teflon based circuit board mounted with the thermoplastic adhesive was measured before and after temperature cycling. The thermoplastic adhesive was shown to be a promising candidate for component and circuit attach.