Effects of epoxy and rubber addition on die attach films (DAFs) materials properties

The trend for package miniaturization brings new packaging techniques such as 3-D stacking including stacking dies, packages, or modules. In 3-D stacking, die stacking method is widely used compared with package or module stacking methods. Die stacking is usually performed using wire bonding, solder bump, or through silicon via(TSV). Among these methods, wire bonding with die attach films (DAFs) has been widely used because of lower cost and easier process than TSV. DAFs are polymer adhesives used for stacking dies. In this study, the properties of DAFs have been investigated by modifying material formulation such as multi-functional epoxy and acrylonitrile butadiene rubber (NBR). Thermo-mechanical properties such as CTE, modulus, and T_g of DAFs and the die shear strength at high temperature were improved as the multifunctional epoxy content increased. In case of rubber addition, thermo-mechanical properties such as CTE, modulus, and T_g of DAFs were deteriorated as the rubber content increased, while moisture absorption decreased as the rubber content increased. Consequently, effects of epoxy and rubber addition on the materials properties of DAFs were fundamentally studied. These results can be used to optimize the DAFs for 3-D stacking dies.