Investigation on bondability and reliability of UV-curable adhesive joints for stable mechanical properties in photonic device packaging

Abstract

The demand for volume deployment of photonic components has increased, and with it the need to effectively manufacture in a reproducible and cost effective way. Therefore, it is important to keep the assembly process consistent and stable. A simple shear test setup was used in this study to determine the shear force that can be used as an instant indicator to the process stability of fiber arrays assembly. The shear test was then used to study the effect of curing conditions, surface roughness, and reliability test on the adhesion of the adhesive joints of single channel fiber arrays. In general, shear force increases with the curing conditions. However, thermal-induced residue stress during improper controlled curing process might lead to loss in ductility and reliability of the joints. Results showed that rough bonding surface for the coverlid can provide better wettability and enhances the shear strength. However, it might result in incomplete polymerization due to transmission loss of UV radiation during assembly process that was caused by the uneven surface. Furthermore, rough surface can affect the flow of adhesive that could result in incomplete-fills. Adhesives at the surrounding of V-grooves and edges of the joints were attacked by moisture at elevated temperature. This paper also discussed in details the possible failure mechanism of adhesive joints after temperature and humidity test.