Press-fit technology has been expected as one of mounting power modules on a printed circuit board (PCB). Since the power modules conduct a high current, resistances of contact portion and a pin itself are important to maintain stable temperature of the power modules and PCB. Also, an offset displacement of the pin and through of PCB should to be considered. Basic behavior of contact resistance and interface reaction were studied. A mixture layer between pin and through hole plating was formed by press-in process, and this process caused to remove an oxide film in order to obtain low contact resistance. Dispite the formation of the mixture layer, contact was not bonded metallically, therefore the function of the contact force is important. To apply pressfit technology to power modules, there are factors to reduce contact force which are the displacement by geometric tolerance and thermal cycle load between the pin and the through-hole of PCB. We solved the problem by designing constriction portion for the body part of press-fit pin, and clarified by thermal cycle test on power modules.
