Effect of boron nitride (hBN) filler on thermal properties of underfill epoxy

In nano-domains, particles of different sizes and surface morphologies affect the properties of materials and its matrix environment uniquely compared to larger size particles. Reducing particle size increases the surface area in contact with the surrounding matrix material such as epoxy resin, along with higher drag and viscosity. Hence, nanoparticles can be exploited to enhance and alter the properties of materials distinctively. Hexagonal boron nitride (hBN) particles of various sizes (1.5μm, 500nm and 70nm) were employed in the fabrication of underfills to investigate the effect of particle size (and surface to volume ratio) on its thermal properties. Filler loadings of 1% to 5% volume fractions were used to prepare underfills using EPONTM Resin 826 and Epikure 3140. The experimental results exhibited that thermal properties of underfills is altered depending upon filler content and particle size. Thermal conductivity of 0.3W/mK was obtained at 5% volume fraction of 70nm hBN filler loading. Furthermore, the influence of filler size and loading on the glass transition temperature (Tg) of the adhesive were studied.