Reliability of Adhesive Attachments on Thick Film Hybrid Substrate

In this paper, the reliability of adhesive flip chip (FC) attachments on thick film hybrid (TFH) substrate was examined. Stud bumped test chips were attached on to the ceramic TFH substrates using anisotropically conductive film (ACF) and non-conductive film (NCF). The reliability of the assemblies was assessed with thermal cycling and constant temperature/humidity testing. Based on the results, both the tested adhesives are well suited for FC attachments on TFH, although the NCF was substantially more susceptible to the bonding pressure than the ACF. The ACF adhesive samples were noticed to outlast NCF ones with all used bonding pressures. Differences in reliability were due to NCF´s low glass transition temperature (T_g) and higher coefficient of thermal expansion (CTE) values, which caused faster relaxation of the contact force, particularly in the temperature cycling test.