Evaluation of Detachable Ga-Based Solder Contacts for Thermoelectric Materials

Kurzfassung

Low electrical and thermal contact resistances are a prerequisite for highly efficient thermoelectric generators. Likewise, certain measurement setups for characterization of thermoelectric materials rely on good-quality contacts between sample and setup. Detachable contacts are an interesting alternative to permanent contacting solutions due to ease of handling and nondestructive disassembly of valuable samples. Therefore, the applicability of gallium-based liquid metal solder as detachable contact material was studied, particularly with regard to compatibility of the solder with state-of-the-art thermoelectric materials CoSb3, Mg2Si, and FeSi2. Tungsten, nickel, chromium, and titanium were tested as protective coatings between the thermoelectric material and liquid metal solder. Electrical measurements showed that some materials form excellent and stable contacts with the solder for a limited temperature range. At higher temperatures, application of a protective layer was found to be necessary for all investigated materials. Tungsten and nickel showed promising results as protective layer.