Regensburg 2019 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 29: Microstructure and Phase Transformations

MM 29.11: Vortrag

Mittwoch, 3. April 2019, 17:45–18:00, H46

Impact of an Effective Triple-line Energy on the Reactive Wetting of Micro-solder on Miniaturized Cu/Ni Tracks — •Samuel Griffiths and Guido Schmitz — Institute for Materials Science, Stuttgart University, Germany

Micro-solder technologies are ubiquitous in modern electronics industries. Although these industries have driven vast practical advancements in solder technologies, little is understood about the impact of miniaturization on the reflow behaviour of solder on metal conductive tracks.

This work quantifies and analyzes the reflow behavior of Sn-based micro-solder on micro-structured Cu and Ni capillary tracks for various track widths, where solder-reflow experiments have been conducted at 350 °C in a reducing flux environment. We show evidence of an effective triple-line energy (~700 mJ/m) which impacts on the steady state system pressure and quantitatively link the triple-line energy to the solder contact angles. The steady state angle at the solder front is compared with a traditional sessile drop wetting angle measurement and, a systematic deviation is observed and discussed.

A scaling-down of the capillary track size down to a few micrometer leads to the interesting case where the track dimensions approach the size of individual substrate grains, thus requiring a modified model for describing the reflow behavior. Electron microscopic imaging and chemical analysis as well as theoretical modelling based on surface, interface and triple-line energy minimization are applied to support our conclusions.