Modeling of growth rate and morphology mechanism of whisker and hillock on micro-bumps under temperature-pressure-humidity storage

A novel model was established to calculate growth rate of whisker and illustrate the morphology mechanism of whisker on fine-pitch Cu pillar micro-bumps under temperature-pressure-humidity storage. Growth of tin whisker and hillock underwent incubation period, quick growth and final steady growth. Theoretical steady-state average growth rate of whisker on micro-bumps calculated by our model were much more accurate than the previous models in order of magnitude. Besides, the diversification of morphologies of tin whisker and hillock were dependent on the synergetic effect of J(L), J(R), slide plane rotation, grain boundary migration and intermetallic compounds particles pinning. The findings are of great significance to the study of tin whisker and hillock on isolated Sn-based solders and provide insights into the reliability of advanced packaging. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

A novel model was established to calculate the growth rate of whisker on fine-pitch Cu pillar micro-bumps and illustrate its morphology mechanism. The calculated theoretical steady-state average growth rate of whisker on micro-bumps was more accurate than previous models. The diversification of whisker morphology was dependent on various factors. These findings are significantly important for improving the reliability of advanced packaging.