Evaluation of thermally conductive adhesives for bonding heat sinks to electronic packages

Two thermally conductive adhesives have been evaluated and found suitable to cover a wide spectrum of heat sink bonding applications. The first adhesive was selected to enhance thermal performance of plastic quad flat packs. In an evolutionary manner, its use was extended to metal, ceramic and low coefficient of thermal expansion (CTE) plastic packages. An empirical fatigue model was developed and coupled with thermal measurements to support bonding to ceramic. The first adhesive offers a lower cost manufacturing process. A second adhesive, that is low in modulus of elasticity was selected to accommodate the severe CTE mismatch between silicon and aluminum. It provides a stable mechanical bond and thermal path in applications where the CTE mismatch is large. Thus, both adhesives and associated processes are used to cover a wide spectrum of heat sink bonding to electronic components