Sinter bonding of inkjet-printed Ag die-attach as an alternative to Ag paste

Abstract

The application of inkjet printing technology to electronic packaging has spurred intense interest since inkjet printing promises superior precision in dispensing of interconnects in a digital and non-contact manner at relatively high speed. Correspondingly, in this study, the advantages and challenges of employing inkjet printing as a means for dispensing die-attach materials for advanced electronic packaging applications are discussed. Recently Ag sinter paste has emerged as an attractive substitute for solders, especially for high-temperature applications. As an alternative to Ag paste, the feasibility of employing an inkjet-printable Ag ink as a novel die-attach material was investigated. Inkjet-printable Ag inks contain a lower amount of Ag in comparison to Ag pastes, enabling a jetting process due to a lower viscosity. Ag particle size and its configuration in an ink are also different from a paste. Consequently, the sinter bonding of the printed Ag die-attach at different temperatures (up to 400 °C) and pressures (up to 20 MPa) was studied. It was revealed that a consistent and crack-free bond-line was produced by inkjet printing. The mechanical properties of the assemblies were subsequently assessed by shear strength analysis.