Interface energy-driven indium whisker growth on ceramic substrates

The mechanism behind spontaneous growth of metal whiskers is essential to develop lead-free whisker mitigation strategy for the sake of long-term reliability of electronics, and has been sought for several decades. However, a consensus about it still lacks, and a host of factors influencing the phenomenon have been investigated, but the role of interface energy has not been paid adequate attention. In this study, the whisker growth propensities of ball-milled Ti2InC/In and non-MAX phase TiC/In and SiC/In are comparatively studied in the terms of the wettability, thermal behavior and crystal structures. The wetting angles of indium with Ti2InC, TiC, and SiC (144.4 degrees, 155.7 degrees, and 142.2 degrees, respectively) are large and quite close, indicating the poor wettability between liquid indium and the three ceramics. The thermal behaviors of all the three systems have obvious changes after ball milling. The number density of indium whiskers on ball-milled Ti2InC is significantly greater than those on the TiC and SiC substrates, which is explained based on interface energy and the crystal structure difference of the ceramic substrates.

Automated summary

The study compared the growth tendencies of metal whiskers, showing that wettability, thermal behavior, and crystal structure play important roles in whisker growth. Interface energy and the crystal structure difference of the ceramic substrates may be key factors influencing whisker growth.