Preparation And Properties Of SiC/Cu Composites With High Volume Fraction Of Silicon Carbide

With the increasing development of semiconductor technology,in order to solve the heat dissipation problem of chips and protect the normal operation of electrical components,it becomes more and more important to find more suitable electronic packaging materials.Because SiC ceramics have good properties such as high strength,high thermal conductivity and low thermal expansion coefficient,SiC has a broad application prospect as a metal-based electronic packaging material formed by reinforcement phase and metal.The thermal conductivity of Cu can reach 400W/(m·K),but its thermal expansion coefficient is 17×10^-6K^-1,which does not match the chip.Therefore,SiC is usually added to reduce the thermal expansion coefficient of the composites to meet the performance requirements.In this experiment,porous SiC ceramics were prepared by aerobic sintering,and high volume fraction SiC reinforced Cu matrix composites were prepared by pressureless infiltration process.The wetting angle between SiC and Cu is more than 140°.The premise of adopting pressureless infiltration method is to improve the wettability between SiC and Cu.In this study,W coating was prepared by sol-gel method and hydrogen reduction method to modify the surface of porous SiC ceramics.The effects of SiC particle size and W coating distribution on the bending strength,thermal conductivity,electrical conductivity and thermal expansion coefficient of the composites were studied.The results are as follows:(1)The SiC green body was prepared by dry pressing method using SiC powder as raw material and phenolic resin as binder.The porous SiC ceramics can be obtained by aerobic sintering at 1350?.The bending strength of porous SiC ceramics with particle size of 10?m is about 30MPa and the porosity is about 40%.(2)The W coating was prepared by sol-gel method,and the solid content of ammonium metatungstate sol was controlled by changing the heating time,and the solids content of 20%,30%,40%and 50% solid content were prepared respectively.The porous SiC was immersed in the sol,then fully dried at 80? and calcined at 600? for 3h,and then reduced by hydrogen reduction at 500? and 800? for 3h,respectively.The W coating with a particle size of about 1?m was prepared.(3)Porous SiC ceramics with particle size of 10?m,50?m and 150?m were used to prepare metal W coating with solid content of 50%.High volume fraction SiC reinforced Cu matrix composites were prepared by pressureless infiltration method,and their thermal conductivity increased from 35.4W/(m·K)to 45.9W/(m·K).The bending strength decreased from 200MPa to 30MPa.The thermal conductivity of the composites increases with the increase of SiC particle size,while the bending strength decreases.(4)The porous SiC ceramic with particle size of 50?m was prepared with 20%,30%,40% and 50% solid content sol respectively,and the W coating with weight gain of 4.0wt.%,7.0wt.%,11.0wt.%and 15.0wt.%was obtained respectively.High volume fraction SiC reinforced Cu matrix composites were prepared after pressureless infiltration.The electrical conductivity and bending strength of the composites decreased with the increase of sol content,the electrical conductivity decreased from 2.8×10⁶S/m to 1.3×10⁶S/m,the bending strength decreased from87MPa to 65MPa,and the thermal expansion coefficient of the composites increased from10.36×10^-6K^-1 to 11.01×10^-6K^-1.