Low temperature sintering-bonding through in-situ formation of Ag nanoparticles using micro-scaled Ag₂O composite paste

In order to reduce the cost of using Ag nanoparticle paste as bonding materials in electronic packaging,microscaled Ag₂O powders were mixed with triethylene glycol (TEG) to form a paste to replace the Ag particle paste.The reaction mechanism of in-situ formation of Ag nanoparticles,the sintering characteristics of micro-Ag₂O paste at low temperature,and the bonding of Ag-coated Cu bulks using this paste were investigated.The results reveal that the Ag₂O particles in the paste were more easily transformed into Ag nanoparticles than micro-Ag₂O itself,and with increasing the sintering temperature,more Ag nanoparticles formed and grew larger by sintering,accompanied with some gaseous products which could escape easily.The effect of sintering-bonding time on the strength of joints fabricated at 250℃ under a pressure of 2 MPa was analyzed.The average shear strength of the joints increased with sintering-bonding time and reached about 24 MPa when the sintering-bonding time was 5 min.And the microstructure of the fractured surface and the cross-section of typical joints made at 250℃ under 2 MPa were also examined.