Nucleation Control and Thermal Aging Resistance of Near-Eutectic Sn-Ag-Cu-X Solder Joints by Alloy Design
- First Online:
- 239 Downloads
Elemental (X) additions to Sn-3.5Ag-0.95Cu (SAC3595) solder were developed with minimal (<0.25 wt.%) concentration to avoid pro-eutectic Ag3Sn blades by reducing undercooling (ΔT) and to eliminate thermal-aging-induced embrittlement. Calorimetry and microstructure results on simple Cu/Cu joints identified 0.21Zn, 0.10Mn, and 0.05Al as sufficient to reduce undercooling below that for SAC3595 and to eliminate Ag3Sn blades. A 211°C melting onset for the X = Mn alloys also suggested the discovery of a new quaternary eutectic. Shear testing and microstructure analysis of larger joints showed that 0.05Al and 0.21Zn additions resulted in reduced as-soldered strength (30 MPa), like Sn-0.95Cu, but all joints showed ductile failure at about 30 MPa after 1000 h at 150°C.
KeywordsPb-free solder (Zn, Mn, Al) additions undercooling Ag3Sn blades shear strength thermal aging
Unable to display preview. Download preview PDF.
- 6.D. Swenson, J. Mater. Sci. Mater. Electron. 18, 39–54 (2007).Google Scholar
- 9.W. Liu, P. Bachorik, and N.-C. Lee, Proc. 58th Electron. Comp. Tech. Conf. (IEEE, 2008), pp. 627–635.Google Scholar
- 10.S.K. Kang, M.G. Cho, P. Lauro, and D.-Y. Shih, J. Mater. Res. 22, 557 (2007).Google Scholar
- 12.J.K. Walleser (M.S. thesis, Mat. Sci. & Eng. Dept., Iowa State University, 2008)Google Scholar
- 14.A. Ohno and T. Motegi, J. Jpn Inst. Metals 37, 777 (1973).Google Scholar
- 15.Materials Preparation Center, A.L., US DOE Basic Energy Sciences, Ames, IA, USA. Available from: www.mpc.ameslab.gov.
- 17.I.E. Anderson, J.L. Harringa, and J.K. Walleser, Proc. 4th Int. Braz. Solder Conf. (ASM Int./AWS, 2009), pp. 68–73, ISBN: 978-0-87171-751-1.Google Scholar
- 23.I. De Sousa, D.W. Henderson, L. Patry, S.K. Kang, and D-Y. Shih, Proc. 56th Electron. Comp. Tech. Conf. (IEEE, 2006), pp. 1454–1461, ISBN: 1-4244-0152-6.Google Scholar