Bonding of power device to ceramic substrate using Sn-coated Cu micro paste for high-temperature applications

[Display omitted] •We prepare Sn-coated Cu particles of different diameters as a micro paste.•We use the paste to bond a dummy chip and a DBC substrate.•The bonding is carried out via transient liquid-phase sintering (TLPS) technology.•The paste affords a high shear strength value of ~40 MPa.•Our approach is suitable for power electronics packaging and allied applications. Cu paste has been considered as a promising substitute for Ag paste for high-temperature-endurable chip-bonding applications, particularly for power electronics packaging, because it is cheaper than Ag. However, the primary disadvantage of using Cu paste is its possible oxidation during the handling and bonding process. In this context, to overcome the oxidation problem of the Cu sinter paste and to exploit the advantages of transient liquid-phase sintering (TLPS) bonding technology, we prepare Sn-coated Cu micro paste in this study, and we evaluate its feasibility as a die-attach material for power electronics packaging. We first prepare various Sn-coated Cu powders under various plating conditions, and we successfully perform TLPS bonding with Sn-coated Cu paste at a relatively low bonding temperature and a short bonding time. During the TLPS bonding, Sn is completely consumed, and the resulting bonded joint is composed of the Cu–Sn intermetallic compounds and remnant Cu particles. The TLPS-bonded joints exhibit relatively high shear strength values of ~40 MPa, and all fractures mainly occur at the chip-side interfaces irrespective of the Cu particle size. We believe that our findings can contribute to the use of Sn-coated Cu paste as an alternative bonding technology for power electronics applications.