Residual stresses in semiconductor laser packaging

The segregation of Au along the crack surface in laser-welded Au-coated Invar for semiconductor laser packaging is investigated experimentally by scanning electron microscope (SEM) mapping, energy dispersive spectrometer (EDS) line profiles, and Auger electron spectroscopy (AES). The results show that the Au accumulates at the crack interface and the concentration of the Au accumulation increases as the bulk Au thickness increases. This indicates that the primary causes of cracks in laser-welded Au-coated materials is the segregation of Au in the final stage of solidification. A finite-element-method (FEM) has been carried out on the analysis of residual stresses in laser packaging. A satisfactory agreement between the experimental results and FEM predictions suggests that the high tensile residual stresses generated by solidification is the possible cause for the cracks