High thermal conductive underfill materials for flip-chip application

Hexagonal boron nitride (h-BN) was applied as a thermally conductive filler to increase the thermal conductivity of underfills. This paper is focusing on the relationship between the filler morphology and its effects on the thermal conductivity. In this study, two kinds of h-BN fillers with different morphologies were applied to generate an efficient thermal transfer path through the filler and epoxy resin interfaces. The microstructure, the dynamic mechanical properties and thermal conductivity for the h-BN filled underfills were characterized. The h-BN greatly increased the thermal conductivity of the underfill and their moduli were well controlled in a low level which can be greatly helpful to reduce thermal stress in flip-chip application.