Study on Bonding of AMB Substrate for Power Semiconductors Using Lotus-type Porous Copper

초록

The increasing environmental concerns have brought electric vehicles (EVs) into the spotlight as the next-generation automobiles. EVs rely on electric motors powered by batteries, with power semiconductors playing a critical role in energy conversion during operation. However, power semiconductors generate significant heat during operation, leading to cracks and reduced durability. To address this, this study proposes the application of lotus-type porous copper to the Active Metal Brazing (AMB) substrate, which is responsible for thermal management and electrical insulation in power semiconductor modules. The conventional AMB substrate, composed of copper (Cu) and alumina (Al₂O₃), suffers from thermal stress due to differences in their coefficients of thermal expansion (CTE). To mitigate this, lotus-type porous copper with a lower elastic modulus and higher flexibility than dense copper was employed. Three types of lotus-type porous copper specimens with different porosities (37%, 42%, 47%) were prepared and bonded to Al₂O₃ substrates. The bonding strength was evaluated, and microstructural analyses were performed. Furthermore, thermal shock tests were conducted to assess the durability of the joints under repeated thermal cycling conditions. The results demonstrate the potential of porous copper structures in enhancing the reliability of AMB substrates for power semiconductor applications. Key Words: Lotus-type porous copper, Al₂O₃, Brazing, Active Metal, Power module