Impact of nano-diamond composites on low-temperature co-fired ceramic interposer for wide bandgap power electronic module packages

Abstract

A 2.5D package with interposer is proposed for wide bandgap (WBG) power modules. Low temperature co-fired ceramic (LTCC) is used for the interposer because its coefficient of thermal expansion (CTE) is closely matched to those of WBG devices as well as its flexibility to have complex structures and through-hole vias built on it. Furthermore, its thermal performance can be enhanced through the addition of through-hole thermal vias. Nano-composite of nano-diamond and silver paste was used as via filled materials in these LTCC interposers. It was found that such interposers with bigger trench vias yielded smaller thermal impedance values while those with circular vias yielded larger thermal impedance values. Scanning acoustic microscopy (SAM) revealed large number of voids in samples with circular vias. As such, besides via filled materials, interposer pattern design, and via dimensions are also crucial in these interposers. Thermal simulations were performed for these interposers and different thermal materials were used and compared.