Facilely Synthesized Ag Nanoparticles Coated Cu Microparticle Interconnect Material for Bonding Bare Cu in the Air at Low Temperature

The accelerated application research of winde bandgap (WBG) power electronic devices intensively stimulates the interconnect materials to catch the capability of serving at high temperatures aligned with low-temperature sintering characteristics. Especially, it is urgently needed the interconnect materials to make the goal of anti-oxidation, anti-migration, and low porosity after sintering. Herein, a novel micro/nano-hybrid structure particles are fabricated by a mild one-step method, which structure is Ag nanoparticles coated Cu microparticle (Cu MP@Ag NPs) with the average size of Ag NPs and Cu MPs being 150 nm and 1.28 μm. Not only do the Cu MP@Ag NPs accomplish anti-oxidation properties at 200 °C for 30 min, but also achieve low-temperature bonding on bare Cu in the air atmosphere, and apart from that, Ag-Cu alloy is formed between Cu MPs and Ag NPs with the increase of sintering temperature. In comparison with Ag NPs paste and Cu MPs paste, Cu MP@Ag NPs paste swallows up the lowest porosity and highest shear strength results at 300 °C sintering, which ascribe to the exquisite micro/nano-hybrid structure particles and the formation of Ag-Cu alloy. The existence of Ag NPs makes the Cu MP@Ag NPs paste possess low-temperature sintering properties and decreases the porosity of the sintering layer by improving the staking density. Besides, the formation of Ag-Cu alloy for one reason is attributed to the formed metallic bonds between Ag NPs and Cu MPs in the synthesis process, and for another reason, it is caused by the greatly increased coarsening driving force by the size difference of the micro/nano-hybrid particles. Furthermore, the fracture mode of the joint using Cu MP@Ag NPs changes to ductile fracture from brittle fracture with the increase of sintering temperatures. This work demonstrates the facilely synthesized stunning micro/nano-hybrid structure particles (Cu MP@Ag NPs) achieve excellent sintering results and possess the potential application in WBG power electronic devices.