WAFER LEVEL PACKAGE USING PRE-APPLIED ANISOTROPIC CONDUCTIVE FILMS (ACFS) FOR FLIP-CHIP ASSEMBLY

摘要

In this study, wafer level flip chip packages using pre- applied ACFs (denoted as ACF-WLPs) were investigated. After ACF pre-lamination on an electroplated Au bumped wafer, and subsequent singulation, and singulated chips were flip-chip assembled on an organic substrate using a thermo-compression bonding method. Au plated bumps were well assembled on Ni/Au pads of organic substrates. The electrical, mechanical properties and the reliabilities of ACF-WLPs were evaluated and compared with conventional ACF flip chip assemblies using thermo- compression method. Contact resistance measurement was performed after under thermal cycling, high temperature/humidity, and pressure cooker test. ACF joints between electroplated Au bumps and substrate metal pads showed stable contact resistance of 5m? per a bump, strong bump adhesion, and similar reliability behaviors compared with conventional ACF flip chip joints using a thermo-compression bonding.