Recent advances in the synthesis of copper-based nanoparticles for metalemetal bonding processes
Yoshio Kobayashi Yusuke Yasuda Toshiaki Morita This review introduces our study on the development of Cu-based nanoparticles suitable as fillers in the metal-metal bonding process. Colloid solutions of various nanoparticles such as cuprous iodide, cupric oxide (CuO), CuO mixed with silver oxide (Ag2O/CuO), cuprous-oxide (Cu2O), metallic Cu, plolypyrrole-coated metallic Cu, and metallic Cu containing metallic Ag (Ag/Cu) were prepared by liquid phase processes such as reduction and a salt-base reaction. Metal-metal bonding properties of their powders were evaluated by sandwiching the particle powder between metallic discs, annealing them at a pressure of 1.2 MPa, and measuring the shear strength required for separating the bonded discs. Various particles (above-mentioned), various metallic discs (Cu, Ag, and Ni), various bonding temperatures (250-400 C), and different atmospheres in bonding (H2 and N2) were examined to find nanoparticle filler suitable for metal-metal bond...