Low Temperature Bonding of Cu Metal through Sintering of AgNanoparticles for High Temperature Electronic Application

摘要

Lead-based solders bring pollution to the environment and result in health threat to humans. The preparationand application of metallic nanoparticles provide a potential method to develop Pb-free bonding materials. In this article,bonding of Ag-coated Cu bulks was realized through low temperature sintering by directly using the chemically-reducedAg nanoparticle paste and baked nanoparticle powders at 60 °C, respectively. The results indicate that the capillary flowof paste caused a ring-like deposit on substrate coating, while this phenomenon disappeared when using the powders.Increasing bonding temperature facilitated the sintering, and shear strengths of 20 MPa and 84 MPa was obtained atbonding temperature of 250 °C for 30 min under 20 MPa when using the Ag paste and powders, respectively. High jointstrength value of bonded region using paste is due to the high effective bonding pressure and small effective bonded area.Finally, for the extensive application in packaging industry especially for high temperature electronics, challenges such asthe improvement of screen and stencil printing ability of paste, avoiding bonding pressure and lowering the cost werepointed out based on our and other researcher's achievements. Cu nanoparticle or Cu-containing nanoparticle mixturepastes are promising but the problems of oxidation and bonding stability must be resolved urgently.