Thin film based passive optical components assembled with a stainless steel tube via soldering is investigated under a packaging procedure. Finite element analysis is utilized to simulate the packaging procedure in the present study. Mismatch of the coefficient of thermal expansion among various components could induce residual stress over the assembly structure. Coupled thermal-elastoplastic analysis is adopted to predict the plastic deformation of the structure under the solidification process of solder joints. This post-solder-deformation could deteriorate the associated coupling efficiency due to the mis-alignment of the optical fibers. Temperature-dependent mechanical properties of the solder joint are employed in the simulations. Both two-dimensional plane strain and three-dimensional solid models are implemented into the analysis for comparisons. In order to improve the fiber alignment, and thus the coupling efficiency, a three-point bending device is externally loaded on the structure. Unloading procedure is subsequently performed to evaluate the ultimate deformed shape of the structure. Measurements of the insertion loss will be conducted using a power meter in the near future, while a correlation between the coupling efficiency and the fiber alignment can then be expected.