Thermal Shock and Joining Characteristics of Lotus-Type Porous Copper/Dissimilar Materials Depending on Pore Filling Ratio

초록

Lotus-type porous copper (LPC) is a metallic material characterized by elongated cylindrical pores, resulting in anisotropic thermal conductivity, excellent fluid permeability, superior ductility, and high energy absorption capability. To explore its industrial applicability, particularly in power module applications for electric vehicles, we investigated the potential of LPC joints. With the increasing use of wide band gap (WBG) semiconductors in electric vehicles, power modules are experiencing higher thermal loads, leading to thermal stress due to mismatched thermal expansion coefficients among stacked heterogeneous materials, which threatens module reliability. As automotive electronics demand high reliability even under extreme conditions, effective thermal stress mitigation and heat management technologies are essential. However, research on LPC joints under such conditions is still lacking. In this study, we evaluated the performance of LPC joints bonded to dissimilar materials under power module operating conditions to assess their ability to address current reliability issues. Comparative experiments were conducted between LPC joints and non-porous Cu joints, focusing first on the changes in joint properties, and subsequently on thermal shock testing to evaluate application potential. The influence of filler material infiltration into LPC pores on yield strength, ductility, and thermal conductivity was also systematically investigate