大功率IGBT散热基板熔融超高热等静压制备技术

High-power IGBT heat sink substrate melting ultra-high heat isostatic pressing preparation technology

铝碳化硅复合材料因其高热导率、低热膨胀率等特性被广泛应用于大功率集成电路封装材料中。本文以压力浸渗法及热等静压法原理为基础,提出一种制备大功率IGBT铝碳化硅散热基板的新型工艺。该工艺创新点在于:(1)无需制备碳化硅预制块,直接灌装碳化硅干粉,碳化硅体积分数可稳定为66%~68%;(2)基板6个外表面均覆盖铝质金属,可实施机械及化学镀镍加工;(3)超高热等静压与真空压铸工艺相结合,渗铝时保压压强达100 MPa左右,可使铝液更好地渗透到碳化硅粉料中,显著减少了气孔、气泡等缺陷,性能更佳。根据检测结果,利用该新工艺,制备的散热基板热导率高达220 W/m·K左右,热膨胀系数为6.5×10^-6~7.5×10^-6/K,其它各项指标均符合使用要求。

Aluminum SiC composites were widely used in high-power integrated circuit packaging materials due to their high thermal conductivity and low thermal expansion rate.Based on the principle of pressure infiltration and hot isostatic pressing,a new process for preparing high-power IGBT aluminum silicon carbide heat-dissipating substrate was proposed.The innovation of this process are:(1)There is no need to prepare silicon carbide preforms,and direct filling of silicon carbide dry powder,the volume fraction of silicon carbide can be stabilized at66%-68%;(2)The outer surfaces of the substrate are covered with aluminum metal,which can be mechanically and chemically plated or nickel processing;(3)Ultra-high heat isostatic pressing combined with vacuum die-casting process,the azeotropic pressure is about 100 MPa,which can make the aluminum liquid penetrate into the silicon carbide powder better,significantly reducing defects such as pores and bubbles,and therefore gains better performance.According to the test results,the thermal conductivity of the prepared heat dissipation substrate can be as high as 220 W/m·K and the thermal expansion coefficient is 6.5×10^-6-7.5×10^-6/K.The other indexes also meet the requirements.