Reliability study of fiber-coupled photodiode module for operation at 4 K.

The reliability of a photodiode module intended for operation at 4K was investigated. Flip-chip bonded photodiodes and an adhesively bonded optical fiber attachment structure were considered. Finite element simulations of the thermomechanical stress were used to evaluate the stresses in different design configurations. Results showed that issues with chip cracking in silicon were eliminated by proper selection of component materials. Photodiode modules survived thermal cycling to 77K and extended operation in 4K.