Fabrication of nanoporous-nanotwinned Cu by dealloying and its application for high-power device packaging

Due to the demanding operating conditions of high-power devices, efficient heat dissipation during packaging is essential. In this study, nanoporous Cu (NP-Cu) with high thermal conductivity (293.3 W/(mK)) was fabricated through co-electroplating Cu-Zn followed by dealloying. Analysis by transmission electron microscopy shows that the NP-Cu consists of nanocrystalline grains with a grain size of 50 nm, 15 % porosity, and its pore size was about 40 nm. The NP-Cu grains also contains nanotwins with a twin spacing of 5 nm. The results showed that using NP-Cu as an interlayer increased the bonding fractions and enabled successful bonding at lower temperatures and pressures. The NP-Cu possessed low yield strength, allowing it more adaptable to various levels of surface roughness and facilitating the bonding. Highly < 111 > -oriented NT-Cu was also applied to enhance bonding. The high-conformity combination of NP-Cu and NT-Cu created a bonding structure with both high thermal conductivity and good reliability, making it a potential thermal interface material (TIM) for high-power device packaging. • NP-Cu with high thermal conductivity was fabricated by co-electroplating and dealloying. • NP-Cu grains also contained nanotwins with a twin spacing of 5 nm. • NP-Cu increased bonding fractions and enabled low-temperature-pressure bonding. • NP-Cu possessed low yield strength, allowing it more adaptable to surface roughness.