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°, 155.7°, and 142.2°, 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 are 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.

Wetting of solid copper with liquid indium in a superhigh vacuum and a gas medium and calculation of their interphase energies depending on the temperature

In the article, using the experimental data obtained in recent years on the contact angles and surface energies of solid copper and liquid indium, their interfacial energies are calculated at different temperatures. Knowledge of the interfacial characteristics is dictated by the need to obtain new materials that can operate under extreme conditions. For these and some other purposes in modern engineering and technology, they began, for example, to use high-vacuum brazing of high-temperature metal products using low-temperature metals and alloys. An important role in such processes is played by the interfacial energy at the solid-melt interface, which determines the contact angle: the lower the interfacial energy, the smaller the contact angle, and the smaller the contact angle, the better the processes of soldering, welding and liquid-phase sintering, etc. etc. Unfortunately, until now there is no direct method for measuring the interfacial energy. Therefore, the calculation of this value is an urgent task.