SMTA International Conference Proceedings


FLIP-CHIP UNDERFILL AND FLUX RESIDUE INTERACTION IN A Pb-FREE PROCESS

Authors: Brian Toleno, Ph.D. et al.
Company: Henkel Loctite Electronics
Date Published: 9/26/2004   Conference: SMTA International


Abstract: Worldwide, electronics manufacturers are investigating new Pb-free alloys and their affects on the reflow process this is an important first step in developing robust Pb-free processes. Once the processes are well developed it is important to determine how these changes will affect the various materials sets in electronic assemblies.

The leading Pb free alloy candidates are the different SnAgCu formulations (often-abbreviated SAC) recommended by NEMI [1] in the United States and IRTI in the EU [2]. The Sn/Ag/Cu eutectic system has a melting point of 217oC, significantly higher than the 183oC melting point of eutectic Sn/Pb alloy. These new alloys increase the peak reflow temperature from 220oC up to 240 or 260oC, a factor that affects material performance. This study deals with one aspect of Pb free processing for array assemblies: underfill/flux adhesion.

Key Words: Pb-Free, Underfill, flux residue.



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