Shearing fracture toughness enhancement for sintered silver with nickel coated multiwall carbon nanotubes additive

Abstract

Shearing fracture behaviors of nickel coated multiwall carbon nanotubes (Ni-MWCNTs) reinforced sintered silver were investigated based on end-notched flexure (ENF) test in this paper. By mechanical mixture of Ni-MWCNTs with sintered silver, an enhanced shearing fracture toughness is obtained at content of 0.5 wt% Ni-MWCNTs . Shearing fracture toughness of sintered silver with different contents of Ni-MWCNTs has been investigated. Upon adding the proper Ni-MWCNTs, the cracking path in sintered silver turns to be cohesive cracking easily, which leads to increase of shearing fracture toughness. The average critical energy release rate obtained at content of 0.5 wt% Ni-MWCNTs sintered silver has been increased by 67.98% and the maximum critical energy release rate was increased to 2.1 times that of average condition in sintered silver without additive. The enhancement mechanism and agglomeration effect of Ni-MWCNTs are discussed. The different microstructure characteristics of Ni-MWCNTs sintered silver are also presented. The fracture properties of sintered silver with different Ni-MWCNTs additive contents are discussed and clarified. The sintered method presented in this paper satisfies the requirements of low temperature and low pressure joining technique in electronics implications. This study presents a novel insight on improving the shearing fracture resistance by adding carbon-based nanomaterial for those die-attaching materials in electronic packaging of power devices.