The Effect of Residual Stress on Coupling Power Loss of VCSEL Modulus

In this article, the effect of residual stress on active region misalignment of laser light sources for vertical cavity surface emitting laser (VCSEL) modulus has been studied. The post-weld-shift variation of active region introduced from the residual stress distribution variation for different VCSEL solder joints, i.e. tin-silver (Sn/3.5Ag) and tin-lead (Sn/37Pb) solder joints, are simulated by employing the thermal-elastic-plastic finite element model of MARC package. The ball grid solidification in reflow process and the creep deformation in the acceleration aging were simulated and analyze. The time and temperature dependent material properties of solders are employed. Numerical results indicate that the post-weld-shift introduced from residual stress in the solidification process are significant, and are also the key reasons to reduce the coupling efficiency in VCSEL packaging. The non-sequential components models in commercial Zemax optical package were used to estimate the optical coupling power loss between the active region and the fiber tip in VSCEL modulus. The results show that the proposed post-weld-shift model is feasible to analyze and to improve the solder joint design in the VCSEL packaging.