超高导热金刚石铜复合材料在GaN器件中的应用

Application of Ultrahigh Thermal Conductivity Diamond Copper Composite Materials on the GaN Device

金刚石铜具有高导热率和低膨胀系数,可用于大功率芯片的散热热沉。未做处理的金刚石表面非常光滑,不易附着其他金属,由于金刚石性质非常稳定,不容易被强酸和强碱进行表面处理。采用JG-01金刚石铜粗化处理液对金刚石进行粗化处理,而对铜无损伤,提升了金刚石表面结合力。金刚石铜镀层对金锡(AuSn)和锡铅(PbSn)焊料的润湿性满足GJB548B-2005要求。GaN功率放大器芯片采用金刚石铜热沉比铜钼铜热沉结温可以降低12℃。金刚石铜载板镀层润湿性良好,焊接后芯片底部的空洞率不大于3%,热沉焊接后空洞率不大于5%,满足高功率芯片散热要求。按照产品环境适应要求,对GaN功率放大器做了高低温冲击和机械振动两种环境筛选实验,最终满足可靠性考核要求。

Diamond copper has a high thermal conductivity and low expansion coefficient, which can be used in the cooling heat sink of high power chips. The surface of the un-plated diamond is very smooth and can not be attached to other metals. Diamond is not easy to be surface treated by strong acid and strong alkali due to its stable properties. Diamond was coarsened with the JG-01 diamond copper coarsening treatment solution. The copper was not damaged, and the surface adhesion of the diamond was enhanced. The wettability of diamond copper coatings to gold tin （AuSn） and lead tin （PbSn） solders satisfied the requirements of GJB548B-2005. The junction temperature of the GaN power amplifier chips using diamond copper as the heat sink can be reduced by 12 ~C than that using Cu/Mo/Cu as the heat sink. Due to the nice wettability of the diamond copper carrier coating, the hole rate of the chip bottom after welding was less than or equal to 3%, and the hole rate of the heat sink after welding was less than or equal to 5%, which satisfied the cooling requirements of high power chips. According to environment adaptation requirements of the product, the high-low temperature shock and mechanical vibration envi- ronment screening experiments of the GaN power amplifier were carried out, satisfying the requirements of reliability assesement.