Properties Of β-SiC_p/Al Electronic Packaging Material Fabricated By Pressureless Infiltration

Silicon carbide reinforced aluminum composites have great potential applications inelectronic packaging because of its high thermal conductivity(TC), high strength, lowcoefficient of thermal expansion(CTE) and low density. The widely used method forfabricating SiC_p/Al composites is pressure infiltration which needs expensive equipments andcomplex process. And the pressureless infiltration processing has the advantage of simpleoperation and low cost. Silicon carbide particle reinforced aluminum composites werefabricated by pressureless infiltration technology in air. And the microstructure and elementdistribution of composites were observed and analyzed. Discussed the principle of thewettability and the mechanism of pressureless infiltration. The TC and CTE in differentprocess of composites were determined. The effects of Mg and Si on infiltration process werestudied. The influence of SiC volume fraction and particle size on thermo-physical propertiesof composite was investigated as well.The results show that the key to compoundβ-SiC_p/Al composites by pressurelessinfiltration is alteration in wettability of theβ-SiC_p/Al interfacial. Oxidation of SiCp play animportant role in interface wettability changing ofβ-SiC_p/Al. It was found that appropriateamount of magnesium added to the aluminum alloy,which involved in reaction with SiO₂ andform MgAl₂O₄. The interfacial reactions enhance the wettability and promote the spontaneousinfiltration process. The harmful interface reactions of forming Al₄C₃ were suppressed on theexperiment conditions by the content of silicon. Microstructural observation on the compositeindicates that the particles in the composites were quite uniform,and the structure were verydense. The results show that increasing the temperature can improve the infiltration rate.The volume fraction of composites was 55%⁷0%,and the range of TC is 140¹70W·m^-1·K^-1,CTE is 6.6⁹.7×10^-6K^-1. With the increasing of SiC volume fraction, the values of thermal conductivity and coefficient of thermal expansion of the composite decrease. Whenthe SiC volume fraction approaches 65 percent,the decrease of thermal conductivity slowsdown. When the SiC volume fraction approaches 68 percent,coefficient of thermal expansionrapidly decreases. When the volume fraction of composites is fixed,interfacial area weregrowth with the increase in size of sic particle,which increase the TC and lower the CTE.