Relationship between bonding conditions and strength for joints using a Au nanoporous sheet

Abstract

As the establishment of high-temperature lead-free solders and other interconnection technologies is an urgent priority in the electronics industry, a strong drive exists to find Pb-free alternatives for high-temperature bonding processes. We propose a no-solvent, no-flux solid-state bonding technique that uses a nanoporous sheet, a process we call nanoporous bonding (NPB). Nanoporous sheets can be made from binary alloys by selective dissolution of one element. In this study, Au nanoporous sheets were fabricated by dealloying a Au-Ag binary alloy with nitric acid. The effects of joining conditions on the shear strength of joints using this sheet were investigated. The joints bonded at 350 °C showed high shear strengths of above 20 MPa. It was found that joining using Au NPB was successfully achieved, and that NPB shows potential as a Pb-free interconnection material for high-temperature electronic applications.