Multimodal particle distribution in 3D-SiC/Al-Si-Mg interpenetrating composite fabricated by pressureless infiltration

Mechanical failure of components used in microelectronic systems is attributed to thermal stress involving temperature fluctuations, which can be eliminated by matching the coefficient of thermal expansion (CTE) of the component parts. Low CTE and high thermal conductivity (TC) 3D-SiC/Al-Si-Mg interpenetrating composites (IPCs) with monomodal or multimodal SiC distribution were fabricated by pressurelessly infiltrating Al-15Si-10Mg into high loading 3D-SiC preforms made from either a single SiC particle size or mixed SiC particles with different sizes of F220, F800 and F1000 mesh, respectively. The effect of monomodal and multimodal SiC distribution on the TC, CTE and bending strength (BS) of the IPCs were carefully studied. In general, 3D-SiC/Al-Si-Mg IPCs with optimized multimodal SiC distribution show better comprehensive properties than 3D-SiC/Al-Si-Mg IPCs with monomodal SiC distribution. The highest TC of 233.22 W/(m degrees C) and BS of 283 MPa as well as lower CTE of 6.32 x 10(-6) C-1 were obtained with the bimodal 3D-SiCF220/800/Al-Si-Mg IPC having a total 73% volume fraction of F220 and F800 SiC. The use of finer F1000 SiC particles in the high loading 3D-SiC preforms could lead to finer SiC particles agglomeration and not well filling in the free space left by coarse SiC network, which result in the microstructural non-uniformity, excessive Mg2Si and retained pores in the prepared IPCs causing the weakening of strength and TC of the IPCs. A significant reduction in CTE of 5.68 x 10(-6) degrees C-1 was achieved on trimodal 3D-SiCF220/800/1000/Al-Si-Mg IPC having a total 79% SiC volume fraction. Moreover, a new model to predict the CTE of IPC based on its 3D interpenetrating network characteristics is proposed which fits well with the experimental CTE data of the IPCs.