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Effects of reflow number and Ag content on microstructure and shear strength of (Au-20Sn)-xAg/Cu joints |
LIU Wensheng, CHEN Baishan, MA Yunzhu, TANG Siwei, HUANG Yufeng |
State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China |
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Abstract Two pure Cu plates were bonded using (Au-20Sn)-xAg(x=0.5, 1, 2) as solder. The effects of reflow number and Ag content on the microstructure and shear strength of (Au-20Sn)-Ag/Cu solder joint were studied. The results show that IMC (intermetallic compound) in the joint line is composed of (Au,Ag,Cu)5Sn after one reflow. The CuAu layer appears after 50 reflows. Lastly, Cu3Au layer appears beside the Cu substrate after 100 reflows. The addition of Ag can suppress the growth speed of the IMC. When reflow number is one, the shear strength of solder joint increases with increasing Ag content. The shear strength of (Au-20Sn)-xAg/Cu (x=0, 0.5, 1, 2) are 92.14, 93.59 and 98.43 MPa, respectively. The shear strength decreases with increasing reflow number, and the decreasing rate decreases with increasing Ag content.
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Received: 26 April 2017
Published: 12 July 2019
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