Research on nano-thermocompression bonding process using nanoporous copper as bonding layer

Low temperature bonding technology has been a research hotspot in recent years due to its success of avoiding impurities interdiffusion, minimizing thermal stresses between heterogeneous materials, minimizing voids and other defects, and reducing the cost. In this work, a novel low temperature thermocompression bonding technology using nanoporous Cu (NPC) was proposed and the influences of different bonding temperatures, pressures and durations upon the bonding qualities were studied. The possible mechanisms of nano-thermocompression bonding were discussed and analyzed. Bonding under the pressure of 0.5MPa for 120min at 250°C resulted in excellent bonding qualities without any interface and voids in the bonded sample examined by means of scanning electron microscopy (SEM) and scanning acoustic microscope (SAM), which shows much potential of this approach in microelectronics manufacturing, 3D packaging and integration of multi-function devices and provides another new way of fabricating direct bonding copper (DBC) ceramic substrate.