Transmission Electron Microscopy Characterization of Ni(V) Metallization Stressed Under High Current Density in Flip Chip Solder Joints
Resource
Journal of electronic materials, 39(12), 2528-2535
Journal
Journal of electronic materials
Journal Volume
39
Journal Issue
12
Pages
2528-2535
Date Issued
2010
Date
2010
Author(s)
Abstract
The Ni(V) under bump metallization (UBM) in flip chip solder joints is known to be consumed in a two-stage process during current stressing. The Ni(V) UBM transforms first to the "consumed Ni(V)" state. Then, this consumed Ni(V) transforms to a so-called porous structure. In this study, the details of the consumed Ni(V) and the porous structure were analyzed by transmission electron microscopy. Bright-field images showed that the consumed Ni(V) was a continuous layer without columnar structures and that the porous structure had many voids in the matrix. The compositional analyses showed that V atoms were immobile and trapped in the original Ni(V) layer. Cu and Sn atoms diffused into the original Ni(V) layer, and Ni atoms diffused outward. Selected-area diffraction patterns and high-resolution transmission electron microscopy of the porous structure showed that it was composed of an amorphous matrix with fine crystalline Cu 6Sn 5 and VSn 2 phases. © 2010 TMS.
Type
journal article
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