The effect of temperature cycling on fiber-solder-ferrule joints in laser module packaging

Abstract

The thermally-induced fiber alignment shifts of fibersolder-ferrule (FSF) joints in laser module packaging have been studied experimentally and numerically. Direct measurements of the metallographic photos with and without temperature cycling, fiber displacement shifts of up to a 0.8 pm were found after undergoing 500 temperature cycles. Experimental results show that the fiber shifts increase as the temperature cycle number and the initial fiber eccentric offset increase. The major cause of fiber shift may come from the plastic solder yielding introduced by the thermal stress variation and the redistribution of the residual stresses during temperature cycling. A finite-element method (FEM) analysis was performed to evaluate the variation of thermal stresses, the distribution of residual stresses, and fiber shifts of the FSF joints. Experimental measurements were in reasonable agreement with the numerical calculations. Both results indicate that the initial offset introduced in the fiber soldering process is a key parameter in causing the thermally-induced fiber shift of FSF joints in laser module packaging. The fiber hft, and hence fiber alignment shift under temperature cycling tests can be reduced si@icantly if the fiber can be located close to the center of the ferrule.

Investigation of Coupling Efficiency by Plastic Deformation of Tube Packaging for Thin-Film-Based Passive Optical Components

“…Furthermore, mechanical properties of the solder joint are assumed to be temperature-dependent. As in Chen [9], Young's modulus, yield stress, CTE, and Poisson ratio for PbSn solder can be respectively formulated in Equations ( 5) -( 8…”