WEB Ceramic Interconnect Technologies for High Temperature Thermoelectric ModulesThursday (24.09.2020) 15:00 - 15:15 F: Functional Materials, Surfaces, and Devices 1 Part of:
The challenge in expanding the range for thermoelectric power generation to temperatures above 300 °C is not only an issue of thermoelectric materials but also
for interconnect technology on the hot side of modules. Replacing toxic bismuth telluride by much more environmentally friendlier Half-Heusler alloys results in a
remarkable increase of exploitable temperatures of up to 800°C. In order to make optimum use of the properties of these materials, low-resistance and temperature-stable current collectors as well as dielectric substrates are required as separators. A commonly applied solution involves direct copper bonded alumina substrates (DCB) consisting of a copper sheet bonded on a ceramic substrate made of aluminium oxide. Beside the advantage of high temperature stability, notably of the ceramic component, this solution lacks on thermal cyclability, critical thermomechanical stresses and cost targets to be met for commercially marketable modules. Within the scope of this work new concepts for hot side interconnects are presented. When ceramic supported metallizations are applied it is necessary to achieve a maximum exploitation of the expensive ceramic material. This can be realized by module concepts with segmented hot side designs, which also minimizes thermomechanical stresses. Efficient metallization (thick film and active metal brazing) and dicing technologies allow a localized usage of the ceramic material by covering the active material only. The use of metal supported hot side interconnects is possible by using inexpensive steel substrates. Customized glass-ceramic materials have been developed, which can be applied to steel substrates by screen printing as layers with thicknesses below 50μm. After firing the layers have a thermal stability up to 600°C. Commercial metallisation pastes based on copper and silver are used for producing metallization layers on top of the glass ceramics. These concepts have been transferred to an automated production process for a new generation of cost efficient thermoelectric modules.