Fabrication And Thermo-mechanical Properties Of SiCp/6061Al Electronic Packaging Material By Powder Metallurgy

Silicon carbide（SiC）-particle dispersed Al-matrix composites with high ceramic content have drawn great attentions as potential candidates for an extensively application prospect in advanced electronic packaging,due to their excellent physical and mechanical properties such as low density,high ratio strength,high thermal conductivity（TC）and low thermal expansion coefficient（CTE）.In this paper,SiCp/6061Al composites with SiC volume fraction of 40-65 vol.%were prepared by powder metallurgy.The effect of preparation process parameters,SiC particle size,particle size distribution and volume fraction on the microstructure,thermal properties and mechanical properties of SiCp/6061Al composites were investigated.The F500-50 vol.%SiCp/6061Al composite was fabricated by high velocity compaction and constant pressure sintering.The effect of compaction height and sintering temperature on the density of composites was studied.When the compaction height,sintering temperature and holding time are 60 cm,700℃and 2 h,respectively,the thermal conductivity of the composite is 179 W/（m·K）,and the average thermal expansion coefficient is 13×10^-6/K.XRD diffraction results show that the composite is mainly composed of Al,SiC and precipitation phase of Si,no Al₄C₃ formation at the interface.Further increase the compaction height or sintering temperature will cause internal crack in SiC or severe interface reaction in composite.F500-50 vol.%SiCp/6061Al composites were prepared by spark plasma sintering.The effect of sintering pressure,sintering temperature and holding time on the microstructure,thermal properties and mechanical properties of the composites were investigated.The results show that the sintering temperature,pressure,and holding time must be properly matched to allow the Al matrix to completely fill the SiC gap without the matrix seepaging out of the die.The composites with 50 vol.%SiC particle sintered at 520℃under a pressure of 50 MPa for 8 min exhibits completely dense structure.SiC particles are evenly distributed in the matrix,and the SiC-Al interface is well-bonded.Relative density,thermal conductivity,average thermal expansion coefficient and bending strength of composite are 99.83%,189 W/（m·K）,11.9×10^-6/K and 649 MPa,respectively.The influence of SiC particle size,grain gradation and volume fraction on the structure,thermal and mechanical properties of SiCp/6061Al composite material was studied.The results show that with the decrease of SiC particle size,the thermal conductivity of composites gradually decreases,and bending strengths gradually increases.Among them,the relative density,thermal conductivity,average thermal expansion coefficient,and bending strengths of F220-50 vol.%SiCp/6061Al composites were 99.29%,233.6 W/（m·K）,10.3×10^-6/K,350.8 MPa,respectively.The60 vol.%SiCp/6061Al composites with bimodal SiC particles,which the volume ratio of F220 to F500 is 3:1,the relative density,thermal conductivity,average thermal expansion coefficient and bending strength of composites are 99.19%,9.77×10^-6/K,227.5 W/（m·K）,364.7 MPa,respectively.With increasing the volume fraction to 65%,the SiCp/6061Al composite sintered at 580℃under a pressure of 80 MPa exhibits the relative density,thermal conductivity,average coefficient of thermal expansion and bending strength of composite are 99.2%,229.8 W/（m·K）,8.71×10^-6/K,351 MPa,respectively,which showed good performance and could meet the requirements of packaging materials.