Effect of adding Ce on interfacial reactions between Sn-3.0Ag-0.5Cu solder and Cu substrate

Abstract

The formation and the growth of Cu-Sn intermetallic compound (IMC) layer at the interface between Sn-3.0Ag-0.5Cu-xCe solder and Cu substrate during soldering and aging were studied. The results show that Cu₆Sn₅ IMC is observed at the interface between solder and Cu substrate in all conditions. After aging for 120 h, the Cu₃Sn IMC is then obtained. With increasing aging time, the scalloped Cu₆Sn₅ structure changes to a plate structure. The Cu₃Sn film always forms with a relatively planar interface. By adding a small amount of the rare earth element Ce (only 0.1%, mass fraction) into the Sn-3.0Ag-0.5Cu solder alloy, the growth rate of the Cu-Sn IMC at the interface of solder alloy system is decreased. When the time exponent is approximately 0.5, the growth of the IMC layer is mainly controlled by a diffusion over the studied time range.

Keywords

intermetallic compound / interface / Sn-3.0Ag-0.5Cu solder / rare earth element

References

[1] KimK. S., HuhS. H., SuganumaK.. Effects of fourth alloying additive on microstructures and tensile properties of Sn-Ag-Cu alloy and joints with Cu [J]. Microelectronics Reliability, 2003, 43(2): 259-267

[2] ChenW. T., LeeS. W., YipM. C.. Mechanical properties and intermetallic compound formation at the Sn/Ni and Sn-0.7wt%/Ni joints [J]. Journal of Electronic Materials, 2003, 32(11): 1284-1289

[3] YuD. Q., WangL.. The growth and roughness evolution of intermetallic compounds of Sn-Ag-Cu/Cu interface during soldering reaction [J]. Journal of Alloys and Compounds, 2008, 458(4/2): 542-547

[4] GhoshG.. Interfacial microstructure and the kinetics of interfacial reaction in diffusion couples between Sn-Pb solder and Cu/Ni/Pd metallization [J]. Acta Materialia, 2000, 48(14): 3719-3738

[5] LiX.-y., YanY.-c., ShiY.-wu.. Influence of IMC on the interface failure of Sn-Ag-Cu/Cu solder joint [J]. Journal of Mechanical Strength, 2005, 27(5): 666-671

[6] YuD. Q., WuC. M. L., LawC. M. T., WangL., LaiJ. K. L.. Intermetallic compounds growth between Sn-3.5Ag lead-free solder and Cu substrate by dipping method [J]. Journal of Alloys and Compounds, 2005, 392(1/2): 192-199

[7] YoonJ. W., KimS. W., JungS. B.. Interfacial reaction and mechanical properties of eutectic Sn-0.7Cu/Ni BGA solder joints during isothermal long-term aging [J]. Journal of Alloys and Compounds, 2005, 391(1/2): 82-89

[8] MaX., QianY. Y., YoshidaF.. Effect of La on the Cu-Sn intermetallic compound (IMC) growth and solder joint reliability [J]. Journal of Alloys and Compounds, 2002, 334(1/2): 224-227

[9] WuaC. M. L.. Properties of lead-free solder alloys with rare earth element additions [J]. Materials Science and Engineering Report, 2004, 44: 1-44

[10] YoonJ. W., JungS. B.. Investigation of interfacial reactions between Sn-5Bi solder and Cu substrate [J]. Journal of Alloys and Compounds, 2003, 359(1/2): 202-208

[11] YoonJ. W., LeeY. H., KimD. G., KangH. B., SuhS. J., YangC. W., LeeC. B., JungJ. W., YooC. S., JungS. B.. Intermetallic compound layer growth at the interface between Sn-Cu-Ni solder and Cu substrate [J]. Journal of Alloys and Compounds, 2004, 381(1/2): 151-157

[12] HiroshiN., JinY. P., TadashiT.. Interfacial reaction between Su-0.7Cu(-Ni) solder and Cu substrate [J]. Journal of Electronic Materials, 2006, 35(5): 1127-1132

[13] PakashK. H., SitharanT.. Interface reaction between copper and molten Sn-Pn solders [J]. Acta Materialia, 2001, 49(13): 2481-2489

[14] LiB., ShiY.-w., LeiY.-ping.. Effect of rare element addition on the microstructure of Sn-Ag-Cu solder joint [J]. Journal of Electronic Materials, 2006, 34(3): 217-224

[15] TuX. N., ThompsonR. D.. Kinetics of interfacial reaction in bimetallic Cu-Sn thin films [J]. Acta Metallurgica Materialia, 1982, 30(5): 947-952

[16] LawC. M. T., WuC. M. L., YuD. Q.. Microstructure, solderability, and growth of intermetallic compounds of Sn-Ag-Cu-Re lead-free solder alloys [J]. Journal of Electronic Materials, 2006, 35(1): 89-93

[17] BoS.-b., ChenY., LüX.-chun.. Thermodynamics calculation and preliminary of the Sn-Ag-Cu-Ce Lead-free solder [J]. Transactions of the China Welding Institution, 2005, 26(5): 20-22

[18] BoS.-b., ChenY., LüX.-chun.. The calculation and application of activity interaction parameter in the Lead-free solder [J]. Transactions of the China Welding Institution, 2005, 26(4): 45-47