Low moisture polymer adhesive for hermetic packages

A novel snap curable organic die attach adhesive has been developed for hermetic packages. This thermoset die-attach paste is suitable for use on conventional dispensing equipment. This material can be cured in less than 60 s at 200°C and does not generate any appreciable weight loss during cure. The authors review the chemical and physical characteristics of the material along with its functional performance as a die-attach medium. The combination of a glass transition temperature around 260°C and high thermal stability up to 400°C provides significant performance enhancement over conventional epoxies. In addition, the material exhibits high adhesive strengths while imparting low stress on the die. Experimental results show that the moisture content in the cavity of a Au-Sn solder sealed ceramic package is less than 1000 ppm. The low moisture characteristic is found to be an inherent property of the material. Reliability tests such as thermal cycling and high temperature storage have shown that the low moisture level is still maintained after 1000 cycles or 1000 h at 150°C