Lin Yixuan,Qi Xiaoquan,Niu Guoqiang,Sun Qin,Ji Hongjun,Li Mingyu,Li Yufeng
Si 3 N 4 is a promising material for heat dissipation substrate due to its excellent thermal conductivity and mechanical properties. However, its application is limited by the difficulties in surface metallization. In this work, surface metallization of Si 3 N 4 ceramic substrate is realized by thick film method for the first time. Conductive silver paste containing Bi 2 O 3 -B 2 O 3 -ZnO glass frit as glass binder was prepared, and high-performance silver thick films were formed on Si 3 N 4 ceramic surface. The mechanical and electrical properties of silver films were significantly promoted with increasing sintering temperature, and silver films with high shear strength of 23.35 MPa and low resistivity of 3.41 μΩ·cm were obtained when sintered at 600 °C. In the meanwhile, the silver films exist high reliability under thermal cycles. The bonding between the silver thick film and Si 3 N 4 ceramic substrate was considerably enhanced as a result of interfacial reaction, forming Bi 2 Si 2 O 5 phase at the interface during sintering process. The formation mechanism was discussed and it is of great significance for the interfacial design in future studies. The results suggest that thick film method is a promising technology for obtaining high-quality surface metallization for Si 3 N 4 ceramic substrate. Graphical abstract
The effect of low I/Ag ratios on the performance of silver thick films containing micro-sized silver particles treated with surface iodination has been investigated. The film with I/Ag ratio of 1:100 exhibited high electrical conductivity and densification, while that of 2:100 presented better adhesion. The conductivity and densification of the film reached the highest at 550 °C. Optimal conductivity of the film with I/Ag ratio of 1:100 and 2:100 was 11.45 and 15.85 mΩ/sq., respectively. In addition, the film adhesion was enhanced by heating. Different trends observed in electrical conductivity and adhesion as functions of temperature is primarily attributed to shrinkage of modified particles. This work suggested that the I/Ag ratio plays a vital effect on the performance of the silver thick film.
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