Fabrication And Properties Of AlSiC Composite Used For Electronic Packaging

With the microelectronic devices developing in a high-performance, lightweight,miniaturization direction, the requirement on electrical packaging material are more and morestringent. AlSiC composite has advantages of cheap raw materials, high thermal conductivityand adjustable thermal expansion coefficient, and gets a more and more extensive applicationin electrical packaging field. AlSiC composite is prepared with ɑ-SiC, aluminium alloymatrix, pore-forming material, binder etc.and prepared by combination of compressionmolding for SiC preform and vacuum pressure infiltration. The microstructure, phase analysis,thermal conductivity and thermal expansion coefficient of AlSiC composite are carried out bySEM, XRD, laser thermal conductance instrument and thermal expansion instrument.The porosity of porous SiC preform was determined by using mass-volume method,Archimedes method and mercury intrusion method, the measured results and Al alloy volumefraction in AlSiC composite were compared. The results prove that the porosity measured bymass-volume method has a excellent agreement with Al alloy volume fraction in AlSiCcomposite. Therefore the mass volume method is a simple and practical method of porositymeasuring; the porosity measured by Archimedes method is relatively smaller; the porositymeasured by mercury intrusion method is relatively larger; Then the effects of thepore-forming agents content on the porosity of SiC porous preform were investigated. Theresults show that the porosity rose unobviously with the content of pore-forming agents whencontent of pore-forming agents was less than5%; and that the porosity rose linearly in generalwhen content of pore-forming agents more than5%. And the porosity tended to40%when thepore-making agents content was14%, which can fully meets subsequent aluminuminfiltration requirements.Detailed microstructure and phase analysis were carried out. The results showed that thecomposite fabricated by above-mentioned methods was free of porosity, and the SiC particleswere distributed uniformly and high interfacial bonding strength was achieved. Moreover, theinterfacial reaction was well controlled so that some harm phases, especially Al4C3fragility,were absent from interfacial reaction products. The coefficient of thermal expansion of aluminum silicon carbide prepared with6061aluminum alloy was7.00×10-6℃-1, the thermalconductivity was155.1W/m.K, and the density was3.1g/cm3. The aluminum silicon carbidecomposite exhibits excellent properties and can fully meet high-end electronic packagingmaterials requirements.The effects of several factors such as matrix metal, binder amount, coarse and fineparticle proportion on thermal conductivity of the composite was investigated. The resultsshowed that the thermal conductivity of the composite taking pure aluminum as matrix washigher than that of taking6061alloy as matrix. The higher the binder amount, the lower thethermal conductivity of the composite. The thermal conductivity of AlSiC compositeincreased with the increase in the coarse SiC particle proportion.The effects of several factors such as pore former amount, binder amount, coarse andfine particle proportion on thermal expansion coefficient of the composite were investigated.The results showed that the higher the pore former amount, the higher the thermal expansioncoefficient. And the higher the binder amount, the lower the thermal expansion coefficient ofthe composite. The thermal expansion coefficient of AlSiC composite increased with theincrease in the coarse SiC particle proportion.