This study aims to develop a bimodal nano-silver paste with improved mechanical property and reliability. Silicon carbide (SiC) particles coated with Ag were introduced in nano-silver paste to improve bonding strength between SiC and Ag particles and enhance high-temperature stability of bimodal nano-silver paste. The effect of sintering parameters such as sintering temperature, sintering time and the proportion of SiC particles on mechanical property and reliability of sintered bimodal nano-silver structure were investigated.
Sandwich structures consist of dummy chips and copper substrates with nickel and silver coating bonded by nano-silver paste were designed for shear testing. Shear strength testing was conducted to study the influence of SiC particles proportions on the mechanical property of sintered nano-silver joints. The reliability of the bimodal nano-silver paste was evaluated experimentally by means of shear test for samples subjected to thermal aging test at 150°C and humidity and temperature testing at 85°C and 85 per cent RH, respectively.
Shear strength was enhanced obviously with the increase of sintering temperature and sintering time. The maximum shear strength was achieved for nano-silver paste sintered at 260°C for 10 min. There was a negative correlation between the proportion of SiC particles and shear strength. After thermal aging testing and humidity and temperature testing for 240 h, the shear strength decreased a little. High-temperature stability and high-hydrothermal stability were improved by the addition of SiC particles.
Submicron-scale SiC particles coated with Ag were used as alternative materials to replace part of nano-silver particles to prepare bimodal nano-silver paste due to its high thermal conductivity and excellent mechanical property.
This work was financially supported by the National Natural Science Foundation of China (No. U1537104), the Key R&D Development Program from the Ministry of Science and Technology of China with the contract number 2017YFB0406000 and Shanghai Municipal Education Commission (Shanghai University High Education Peak Discipline Program). The authors also thank for the financial support from the Swedish Foundation for Strategic Research (SSF) with the contract number GMT14-0045 and from the Production Area of Advance at Chalmers University of Technology, Sweden.
Zhang, Q., Zehri, A., Liu, J., Ke, W., Huang, S., Latorre, M.G., Wang, N., Lu, X., Zhou, C., Xia, W., Wu, Y., Ye, L. and Liu, J. (2019), "Mechanical property and reliability of bimodal nano-silver paste with Ag-coated SiC particles", Soldering & Surface Mount Technology, Vol. 31 No. 4, pp. 193-202. https://doi.org/10.1108/SSMT-05-2018-0014
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