Enhancements on Underfill Materials' Thermal Conductivity by Insulation Coating Layer Control of Conductive Particles

Abstract

In this study, an alumina coated silver core/shell structure particles were prepared through a sol-gel approach. Various techniques were used to characterize the as-prepared products, including field emission scanning electron microscopy (FE-SEM), field emission transition electron microscopy(FE-TEM), energy-dispersive X-ray spectroscopy (EDS) and thermal transient method. FE-SEM images showed a morphology of alumina coated Ag(ACA) particle and FE-TEM images showed a cross- section of synthesized alumina shell. EDS mapping confirmed that the synthesized shell was composed of Al and O. The thickness of the alumina shell satisfying high insulation resistivity and thermal conductivity was 23.5 nm. The electrical resistance and thermal conductivity of underfill using this alumina coated Ag (ACA) particle was 1.6E12 Omega-cm and 1.9 Wm(-1)K(-1). When alumina coated Ag (ACA) particle and alumina were mixed to increase the thermal conductivity, it could be possible to achieve 2.34 Wm(-1)K(-1).