高体分比SiCp/Al复合材料的近净成形技术

Near Net-Shape Forming of High Volume Fraction SiCp/Al Composites

高体积分数SiCp／Al复合材料具有优异的热物理性能，且密度较低，是非常理想的电子封装材料。但是由于其本身高的脆性和硬度，使得该材料很难通过二次机械加工成所需要的形状，严重制约了该材料的应用：采用粉末注射成形-无压熔渗工艺成功实现了高体积分数SiCp／Al复合材料的近净成形：采用该工艺所制备的复合材料的致密度高于99％，可实现热膨胀系数在（5—7）×10^-6K^-1范围内进行调节，材料的热导率高于185W／（m·K），抗弯强度高于370MPa，气密性可达10^-11Pa·m^3·s^-1，各项指标均叮以满足电子封装对材料的性能要求，另外为了实现SiCp／Al复合材料与其他材料的封接，项目成功开发了一种Al—Si—Cu系焊料，封接后器件的各项性能指标尤其是气密性也均能满足使用要求。

High volume fraction SiCp/Al composite is a perfect electronic packaging material because of its excellent thermal-physical properties and lower density. However, this material has not been widely used in the field of packaging because it is hard to be machined into complex-shape due to its greater hardness and brittleness. In this paper, the preparation of SiC preforms by ceramic injection molding （CIM） , pressureless infiltration of SiC preforms by Al alloys and some other basic questions have all been studied to found a CIM-pressure infiltration new technology, and in the end, the net-shape preparation of high volume fraction SiCp/Al composites have been successfully realized. The relative density of prepared SiCp/Al composite is high than 99% , CTE can be regulated in（5 - 7）× 10^-6 K^-1 according to actual needs, thermal conductivity is higher than 190 W/（ m ·K） , bending strength is higher than 370MPa and gas impermeability value is near 10^-11Pa·m^3·s^-1. These thermal-physical and mechanical properties can better match the requirement of electronic： packaging technology on the materials. Furthermore, in order to seal SiCp / Al composites, a kind of Al - Si - Cn system solder has been successfully developed, the sealing performance of the device can also meet the requirements.