| In recent years,there is a big gap between domestic silver powder products and foreign ones in terms of morphology and structure,which leads to the fact that the high-quality conductive silver powder and silver paste required by domestic photovoltaic,electronic,aerospace and other fields have always been imported.At the same time,the conductive silver paste using silver powder sintering temperature is higher,about850℃,and the resistivity is larger,higher sintering temperature and greater resistivity will greatly affect the life and performance of electronic components.To solve the problem of high sintering temperature and high resistivity of silver powder for conductive silver paste.The shape and size of the silver powder directly affects the sintering temperature and conductivity of the conductive silver paste.For this reason,it is important to study the shape and size of conductive silver powders.Therefore,the development of silver powders with low sintering temperature and low resistivity is of great practical importance.The main results of this thesis are as follows.（1）Spherical,flake,lump,flower,hairline ball and needle shaped silver powders were prepared by the liquid phase reduction method using Ag NO3 as raw material and Fe SO4 as reducing agent.The additive citric acid is a key factor affecting the size and shape of the silver powders.The size of the spherical silver powder prepared without citric acid was about 3μm;the size of the flake silver powder prepared at a concentration of 0.015 mol/L was about 3.5μm;the size of the spherical silver powder prepared at a concentration of 0.06 mol/L was about 0.5μm.（2）Silver powders of different shapes,sizes,specific surface areas and composite shapes and sizes were selected for sintering and resistivity testing.For spherical silver powders,the resistivities of 0.6μm and 2μm silver powders at the optimum sintering temperature of 250°C were 1.92×10-6Ω·m and 2.46×10-7Ω·m,respectively;the resistivity of 1μm silver powder at the optimum sintering temperature of 150°C was16.5×10-7Ω·m;the resistivity of 3μm silver powder at the optimum sintering temperature of 550°C was 2.39×10-7Ω·m.-m.For silver flake powders,the resistivities of 0.5μm,1μm,2μm and 3μm silver powders at the optimum sintering temperature of 150°C were 11.53×10-7Ω·m,1.85×10-7Ω·m,1.61×10-7Ω·m and 4.77×10-6Ω·m,respectively.For bulk silver powders,the resistivities of 0.2μm and 2μm silver powders were 2.6×10-6Ω·m and 4.81×10-7Ω·m at an optimum sintering temperature of 250°C,respectively;the resistivity of 1μm silver powder was 1.35×10-6Ω·m at an optimum sintering temperature of 350°C.The resistivity of the 3μm fancy silver powder at an optimum sintering temperature of 350°C was 15.94×10-7Ω·m.The resistivity of the 3μm hairline spherical silver powder at an optimum sintering temperature of 350°C was 19.34×10-7Ω·m.In addition,for the composite silver powder,the resistivity gradually decreases with the increase of spherical proportion;For composite size silver powder,with 3μWith the increase of m ratio,the resistance first increases,then decreases,and then increases;For silver powder with different specific surface areas,the resistance first increases and then decreases with the increase of specific surface area. |
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