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For several years, an approach to use fine-pitch flip chip package (<150um) with copper pillar/ micro-bump is for the realization of 2.5D/3D packages of higher density and performance enhancement. Generally, flux is widely used to clean the surfaces to be soldered for good wetting and form reliable joints. The upcoming concerns about fluxes are clean-ability for fine-pitch package, voiding and compatibility with underfill materials. There is a tradeoff between flux characteristics and soldering performance.
At the upcoming 13th International Wafer Level Packaging Conference (IWLPC), SHENMAO Technology Inc. will present a paper on a formulated no clean flux for fine-pitch flip chip package of copper pillar/micro-bump interconnect. This paper will discuss in details about the applicability of a new no clean flux in fine-pitch flip chip interconnect from the point of view of flux formulations, including flux activity for wetting performance, rheological characterization for the study of behaviors during reflow process and the evaluation of compatibility with underfill.
Authored by Hsiang-Chuan Chen, Ya-Ching Chuang, Chia-Hao Chang, and Watson Tseng, the paper will be presented during the Interactive Presentations session on October 18, 10:00 am to 1:30 pm.