Study on the Hygrothermal Reliability of Underfill/Passivation Layer Interface Using the Silane Coupling Agent as Adhesion Promoter

Due to the low adhesion caused by moisture absorption, the delamination between the underfill and the passivation layer of the chip has been proved to be a critical problem to determine the packaging reliability. In this study, five different silane coupling agents were added to underfill and their reliability at the underfill and passivation layer interface was investigated under hygrothermal conditions. Shear tests at room temperature and high temperature were carried out to evaluate the interfacial adhesion. It was found that after hygrothermal aging, the adhesion of underfill without coupling agent was severely degraded for the passivated layer; however, after adding coupling agent, the coupling agent enhanced the hygrothermal reliability of the interface due to the formation of chemical bonds, especially the silane coupling agent with epoxy and amino groups. It showed good interfacial adhesion under both room temperature and high temperature conditions before and after hygrothermal aging.