Effect of thermal cycling on the growth of intermetallic compounds at the Sn-Zn-Bi-In-P lead-free solder/Cu interface
| Autor: | Jusheng Ma, Guohai Chen, Xiaoyan Li |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Materials science
Scanning electron microscope Metallurgy Intermetallic Temperature cycling Condensed Matter Physics Thermal diffusivity Electronic Optical and Magnetic Materials Electron diffraction Transmission electron microscopy Soldering Materials Chemistry Electrical and Electronic Engineering Eutectic system |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 1543-186X 0361-5235 |
| DOI: | 10.1007/s11664-006-0170-5 |
| Popis: | The low-temperature Sn-9Zn-1.5Bi-0.5In-0.01P lead-free solder alloy is used to investigate the intermetallic compounds (IMCs) formed between solder and Cu substrates during thermal cycling. Metallographic observation, scanning electron microscopy, transmission electron microscopy, and electron diffraction analysis are used to study the IMCs. The γ-Cu5Zn8 IMC is found at the Sn-9Zn-1.5Bi-0.5In-0.01P/Cu interface. The IMC grows slowly during thermal cycling. The fatigue life of the Sn-9Zn-1.5Bi-0.5In-0.01P solder joint is longer than that of Pb-Sn eutectic solder joint because the IMC thickness of the latter is much greater than that of the former. Thermodynamic and diffusivity calculations can explain the formation of γ-Cu5Zn8 instead of Cu-Sn IMCs. The growth of IMC layer is caused by the diffusion of Cu and Zn elements. The diffusion coefficient of Zn in the Cu5Zn8 layer is determined to be 1.10×10−12 cm2/sec. A Zn-rich layer is found at the interface, which can prevent the formation of the more brittle Cu-Sn IMCs, slow down the growth of the IMC layer, and consequently enhance the fatigue life of the solder joint. |
| Databáze: | OpenAIRE |
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