Thermoelectric conversion module and production method therefor
A production method for a thermoelectric conversion module having a thermoelectric conversion element and an electrode, which are metallurgically bonded together via a porous metal layer. The porous metal layer is made of nickel or silver and has a density ratio of 50 to 90%.
1. A production method for a thermoelectric conversion module having a thermoelectric conversion element with an end surface and having an electrode, the production method comprising:
preparing a paste in which nickel powder particles are dispersed, the nickel powder particles having an average particle diameter of 0.1 to 10 μm;
applying the paste to the end surface of the thermoelectric conversion element;
abutting the end surface, to which the paste is applied, to the electrode so as to connect the thermoelectric conversion element and the electrode;
heating the paste between the thermoelectric conversion element and the electrode in an inert gas atmosphere, a reducing gas atmosphere, or a vacuum atmosphere, so as to remove the paste except for the nickel powder particles and cause the nickel powder particles to remain;
sintering the remaining nickel powder particles so as to form a porous nickel layer; and
diffusion bonding the porous nickel layer to the end surface of the thermoelectric conversion element and to the electrode so as to metallurgically bond them,
wherein the sintering and the diffusion bonding are simultaneously performed at a temperature of 650 to 850° C.
2. The production method for the thermoelectric conversion module according to claim 1 , wherein the nickel powder particles are dispersed in the paste at 30 to 50 volume %.
3. The production method for the thermoelectric conversion module according to claim 1 , wherein the paste has a viscosity of 10 to 100 Pa·s.
4. The production method for the thermoelectric conversion module according to claim 1 , wherein the paste has a shear strength of not less than 0.1 N/cm 2 .
5. The production method for the thermoelectric conversion module according to claim 1 , wherein the end surface of the thermoelectric conversion element is covered with a metal, and the paste is applied to the end surface covered with the metal.
6. The production method for the thermoelectric conversion module according to claim 1 , wherein the porous nickel layer has a density ratio of 50 to 90%.
7. The production method for the thermoelectric conversion module according to claim 1 , wherein the porous nickel layer has a thickness of 10 to 100 μm.
8. The production method for the thermoelectric conversion module according to claim 1 , wherein the sintering and the diffusion bonding are performed without applying pressure, or are performed by applying pressure of not more than 1 Mpa.