Cu-Cu joint formation by sintering of self-reducible Cu nanoparticle paste assisted by MOD under air condition

As the electronics industry develops, semiconductor devices increasingly tend to be used in high temperature application. Higher working temperature also puts forward new requirement for die-attach materials, copper nanoparticles (Cu NPs) have shown great promise as a die-attach material due to its excellent thermal and electrical conductivities. However, Cu NPs are easily oxidized. In this article, we introduce a self-reducible Cu NPs paste compose of Cu-based MOD, reducing solvent and commercial Cu NPs (100 nm), and the sintered joints can achieve high shear strength in air. The copper produced by the decomposition of self-reducible MOD helps sintering between copper nanoparticles and has a certain effect of inhibiting oxidation. The influence of MOD content on shear strength and sintered layer structure was explored. Finally, reliable Cu-Cu joints with a shear strength of 20.47 MPa was achieved with 250 degrees C bonding for 15 min in air. This novel Cu NPs paste is promised to be used as a bonding material for electronic packaging and provides a new method for copper sintering in air.