利用多物理场仿真软件COMSOL Multiphysics分别对不同厚度焊料以及不同厚度WCu次热沉封装的大功率半导体激光器巴条进行模拟。结果表明:无论是In焊料还是AuSn焊料,其最大热应力均产生于WCu次热沉与Cu热沉界面处;相同厚度In焊料和AuSn焊料封装的激光器管芯热应力分别为3.57 GPa和3.83 GPa,光谱峰值处波长分别为800.5 nm和798 nm;降低焊料的厚度,有利于减小激光器管芯内部的热应力和温度,但焊料厚度过薄,则可能会导致激光器管芯焊接不牢或焊料分布不均匀、焊料层内部出现空洞等现象,因此焊料厚度的选择应从整体进行考虑;随着WCu次热沉厚度的增加,激光器芯片受到的热应力变小,但管芯温度升高,WCu次热沉的最优厚度为380 μm。本研究结果为优化设计大功率半导体激光器巴条的封装提供了依据,对实际生产具有指导意义。

Semiconductor laser bars packaged with different thicknesses of solders and WCu submount are simulated using the multi-physical field simulation software of COMSOL Multiphysics. Results demonstrate that the maximum thermal stress of an In or AuSn solder occurs at the interface between the WCu submount and Cu heat sink. Thermal stresses of laser dies packaged using an In solder and an AuSn solder with the same thickness are 3.57 GPa and 3.83 GPa, respectively, and the corresponding wavelengths at the peak of spectrum are 800.5 nm and 798 nm, respectively. Reducing the solder's thickness is beneficial for reducing the thermal stress and temperature in the laser die. However, if the solder's thickness is too thin, it may cause weak welding of the laser core or uneven distribution of the solder, forming voids in the solder layer; hence, the selection of solder thickness should be considered as a whole. With increasing thickness of the WCu submount, the thermal stress of the laser die decreases; however, the temperature of the core rises. The optimal thickness of the WCu submount is 380 μm. This study provides a basis for optimizing the packaging of high-power semiconductor lasers and has guiding significance to practical production.