EFFECT OF ELECTROLESS Ni-P PLATING ON THE BONDING STRENGTH OF Bi-Te-BASED THERMOELECTRIC MODULES.

In the present study, electroless Ni-P plating was applied to Bi-Te-based thermoelectric materials as a barrier layer and the effect of the Ni-P plating on the bonding strength of the thermoelectric module was investigated. The bonding strength of the n- and p-type modules increased after being subjected to the electroless Ni-P plating treatment. In the case of the thermoelectric module that was not subjected to electroless Ni-P plating, Sn and Te were interdiffused and formed a brittle Sn-Te-based metallic compound. The shearing mostly occurred on the bonding interface where such an intermetallic compound was formed. On the other hands, it was found from the FE-EPMA analysis of the bonding interface of thermoelectric module subjected to electroless Ni-P plating that the electroless Ni-P plating acted as an anti-diffusion layer, preventing the interdiffusion of Sn and Te. Therefore, by forming such an anti-diffusion layer on the surface of the Bi-Te based thermoelectric element, the bonding strength of the thermoelectric module could be increased. [ABSTRACT FROM AUTHOR]