Ambient Low Temperature Cu Bonding Technique(3/3)

This project will develop Cu and Cu(Sn) pastes that can be sintered for Cu-Cu direct joints at low temperature in ambient. The essence of the project combines the knowledge of inorganic Cu and organic polymer. Cu and Cu(Sn) pastes can be applied to 3D IC interconnects, direct bonding copper for high-power device and flexible print circuit board. The principle of the idea is to sinter Cu nanoparticle by reducing organic acid. With the addition of Sn nanoparticles, a paste of these metallic particles can be fabricated. Preliminary research results indicated that the pastes can be sintered at 200 oC at ambient pressure. This project aims to lower the sintering temperature and optimize the parameters. The pastes will be applied on copper, ceramics, and flexible polymer substrates. The pastes will be applied to Cu wires in micron size. Electrical, mechanical, microstructure and sintering mechanism of the pastes will be investigated in-depth. Finally, the microstructure of the sintering processes will be studied by using FIB, TEM, EBSD and X-ray tomography, and the sintering model will be proposed.