Effect of hybrid filler ratio and filler particle size on thermal conductivity and oil bleed of polydimethylsiloxane/Al_2O_3/ZnO liquid thermal filler for microelectronics packaging applications

摘要

A high thermal conducting, electrically insulating, and non-oil bleed liquid thermal gap filler containing aluminum oxide (Al_2O_(310 μm）) and zinc oxide (ZnO_(0.6 μm)) in polydimethylsiloxane (PDMS) has been fabricated. An effective method of mixing 93 wt% filler in 7 wt% PDMS was achieved without surface modification. It was found that the thermal conductivity, hardness, dielectric constant, and dielectric loss tangent values increased with the variation of filler ratio. The S5 hybrid composite exhibits the highest thermal conductivity of 3.38 W/m K, which was 21.1 times higher than that of pure PDMS. The corresponding dielectric constant and dielectric loss were 7.968 and 0.03076 at 1 MHz. TGA results revealed that the variation of Al_2O_3/ZnO filler ratio improved the maximum decomposition temperature of the composite. Furthermore, no oil bleed was observed for the entire composites after 1 month. Thus, fillers with different particle sizes provide more significant filler packing density in the matrix and lower thermal resistance between adjacent conductive filler, resulting in high thermal conductivity composites.