Reliability assessment of high density fine pitch lead-free flip chip package

Abstract

It is now possible to build high performance integrated circuit (IC) due to the recent advancement in the chip fabrication process. To meet the high performance IC, the chip's input/output (I/O) counts have to increase and this resulted in fine pitch and large IC. In addition, there is a drive towards using environmental-friendly material. The lead free solder, fine pitch, large die and organic substrate are features commonly found in the high performance IC package. However, these features pose a significance challenge to the package reliability in terms of moisture sensitivity test and temperature cycling performance. The concern arises due to the compatibility issues involving the underfill, flux, passivation material and the under-bump metallization (UBM). However, material compatability is only part of the reasons. Others include Pb free solder, large die, fine pitch, organic substrate which are not addressed in This work. The objectives of this work are optimizing of the assembly process and identifying suitable material set for a reliable high-density fine pitch lead free flip chip organic package.