Study On Interfacial Control And Properties Of The Al₂O₃/Al Composite

With the rapid development of electronic information technology and semiconductor technology,integrated electronic circuits put forward higher performance requirements on the packaging technology.Therefore,it also attracted the researchers continue to develop low cost,simple process,low density,high thermal conductivity,low coefficient of thermal expansion electronic packaging materials.In this study,the three-dimensional network alumina ceramic were used to enhance the aluminum metal,using the the surface activation layer to improve the bonding of interface,in order to obtain high strength and stiffness,high abrasion resistance,small coefficient of thermal expansion,good thermal conductivity and electrical conductivity electronic packaging materials continuous structure in space.The alumina was prepared by organic foam impregnation method.Next,the silica coating on the surface were prepared by dip-coating method,and the nickel coating were getted by chemical vapor deposition method.Then,the matrix aluminum was filled in the mesh of the three-dimensional Al2O3 reinforcements by vacuum lost foam casting method,and the three-dimensional Al₂O₃/Al composites were obtained.Through the controlment of the coating preparation process to obtain different thickness coating,studied the effects of coating type and thickness on the bulk density,porosity,bending strength,electrical conductivity,coefficient of thermal expansion and thermal conductivity of the composites.Research results indicates that:?1?By the controlling of dipping times in dip-coating and holding time in chemical vapor deposition method,3.44²1.25?m SiO₂ coating and 2.06¹1.92?m Ni coating were obtained.?2?Compared to uncoated interface,coated interface with 9.23²1.25?m SiO₂ and 4.65¹1.92?m Ni both can significantly improve the wettability between alumina and aluminum,acquring interfaces without cracks,porosity and other defects in the Al₂O₃/Al composite materials.?3?The increase in coating thickness give rise to reducing of the porosity,and cause the appearing of maximum value in bending strength of the composite material.When the thickness of SiO₂ coating is 13.92?m and Ni coating is 7.86?m,the flexural strength of composites reaches crest value 110.65 MPa and 102.39 MPa respectively.?4?The higher the volume fraction of the reinforcement,the stronger the constrained capacity to matrix,the lower the coefficient of thermal expansion.The introduction of 27.08% reinforced phase alumina ceramic,the coefficient of thermal expansion of composite decreases from 23×10-6/? to 11.04×10-6/?,achieving a good match with the semiconductor material.The larger the thickness of the coating,the more obvious the improvement effect on the interface,the lower the coefficient of thermal expansion.?5?The thermal conductivity of the composites increases with the increase of the coating thickness.The thermal conductivity of the composites reaches 133.6W?m-1?K-1 with 21.25?m SiO₂ coating,and 141.6W?m-1?K-1 with 11.92?m Ni coating.The Al₂O₃/Al composite has good thermal conductivity.