C4NP technology: Present and future

Abstract

Pb-free C4NP implementation for 200um pitch flip chip started at IBM in June, 2007. Since then, 150 um pitch has been qualified as well. For high end servers which require higher level of reliability, IBM is currently qualifying C4NP for Pb solders transfer. As technology demands finer pitch, the C4NP technology, fill and transfer processes, has demonstrated great flexibility and extendibility to meet a wide range of applications. Mold changes for increased volume for fine-pitch micro-bump applications have been developed which include RIE processes for better depth/width aspect ratios, and to achieve better uniformity in cavity volume. With these improvements, C4NP is well suited for the 3D applications, including 50 =m pitch and below bumping applications.