Thermally Conductive Adhesives for Microelectronics - Barriers of Heat Transport

Thermally conductive adhesives consist of the polymer base material matrix and the conducting filler dispersed randomly. It is commonly believed, that similarly as in the case of electrically conductive adhesive, with content of filler above the percolation threshold, the heat conduction depends mainly on the filler material bulk thermal conductivity. In fact, the heat transport inside an adhesive formulation is strongly constricted by the existing thermal contact resistance between filler particles. Additionally, the heat transport is limited by a bond resistance. The adhesive bond resistance in comparison to the total resistance of the thermally conductive adhesive joint becomes an important factor especially in case of microelectronic packaging where the adhesive layer thickness can be of the order of micrometers.