Wafer level packages (WLPs) using anisotropic conductive adhesives (ACAs) solution for flip-chip interconnections

In this study, wafer level packages (WLPs) using anisotropic conductive adhesives (ACAs) solution for flip-chip interconnections have been newly developed and the effects of process parameters on the wafer level package performance were investigated. At first, the effect of coating process parameters such as blade gap and temperature were investigated for uniform thickness coating without voids and bubbles on a Au bumped wafer. After solvent drying and the subsequent singulation of a B-stage ACA solution coated wafer, singulated chips were flip-chip assembled on organic substrates using a thermo-compression bonding method. The reliabilities of flip chip assemblies using WLP were evaluated in terms of high temperature/humidity, and pressure cooker test and compared with those of conventional anisotropic conductive film (ACF) package. In high temperature/humidity reliability test, there was no difference of flip chip reliabilities between two types of flip chip assemblies. Furthermore, in pressure cooker test (PCT), WLP using ACAs solution showed better reliability than conventional ACF package.