Thermodynamics-aided alloy design and evaluation of Pb-free solder, Sn-Bi-In-Zn system
- Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Materials Science and Engineering
- Korea Research Inst. of Standards and Science, Taejon (Korea, Republic of). Materials Evaluation Center
Lead-tin (Pb-Sn) solder alloys have been widely used in the modern electronics industry because of their low melting points, good wettability, good time-dependent deformation characteristics, good corrosion resistance and reasonable electrical conductivity. However, due to increasing environmental and health concerns over the use of lead, alternative lead-free solder alloy systems are strongly needed. To design Pb-free solder alloys which are drop-in replacements for 63Sn-37Pb (compositions are all in weight percent, otherwise specified), thermodynamic studies on the Sn-Bi-In-Zn quaternary system were carried out in terms of phase equilibria. Based on the results of phase equilibria calculations, several specific alloy compositions were selected and analyzed using differential scanning calorimetry (DSC) measurements. DSC results were compared with thermodynamically calculated phase transition and melting temperatures. Liquidus temperatures were slightly higher than 200 C, however, solidus temperatures were lower, in the range of 130--180 C. Microstructures of as-cast and heat-treated alloys were examined through scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. Wetting tests were also performed at 240 C to investigate the interfacial reaction between the Cu substrate and solder alloys. The Cu{sub 5}Zn{sub 8} intermetallic phase was found at the interface instead of the Cu{sub 6}Sn{sub 5} or Cu{sub 3}Sn in phases that are normally observed in Sn-base solder alloys.
- OSTI ID:
- 483612
- Journal Information:
- Acta Materialia, Vol. 45, Issue 3; Other Information: PBD: Mar 1997
- Country of Publication:
- United States
- Language:
- English
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