Low-temperature solid state bonding method based on surface Cu–Ni alloying microcones

A low-temperature solid state bonding method based on surface Cu–Ni alloying microcones for potential application in 3D integration is introduced. Surface Cu–Ni alloying microcones were fabricated by electroless deposition and bonded with Sn–3.0Ag–0.5Cu (wt.%) solder at 190 °C (solid state) in ambient air. Microscopic observation showed that Cu–Ni microcones inserted into the soft solder effectively and a thin intermetallic compound layer formed along the bonding interface. The bonding joint strength was measured and the result showed that it was higher than that of reflow soldering.