| About this Abstract |
| Meeting |
2024 AWS Professional Program
|
| Symposium
|
2024 AWS Professional Program
|
| Presentation Title |
Microstructural Coarsening Kinetics and Mechanical Property Changes in Long-term Aged Sn-Pb-Sb Solder Joints |
| Author(s) |
Donald F. Susan, Rebecca Wheeling, Shelley Williams, Jeier Yang, Celedonio Jaramillo |
| On-Site Speaker (Planned) |
Donald F. Susan |
| Abstract Scope |
Tin-lead-antimony (50Sn-47Pb-3Sb wt.%) soldered assemblies were tested approximately 30 years after initial production and found to have lower strength. The microstructure of this solder alloy exhibits a ternary eutectic structure with Sn-rich, Pb-rich, and SnSb phases. Accelerated aging was performed to evaluate solder microstructural changes and gather mechanical property data to correlate to the naturally aged solder joints. Isothermal holds were performed at room temperature, 55, 70, 100, and 135°C with hold times ranging from 0.1 to 365 days. The coarsening kinetics of the Pb-rich phase were determined through optical microscopy and image analysis methods established in previous studies on binary Sn-Pb solder. Accelerated aging at 70-100°C for 100-200 days produced microstructures similar to the naturally aged 30-year-old solder joints. Compression testing and Vickers microhardness showed notable decreases within the first 20-30 days after soldering, although the microstructure and properties continue to change slowly over long periods of time, thereby extrapolating fairly well to the 30-year aged condition. However, aging at the highest temperature of 135°C produced anomalous behavior suggesting other aging mechanisms are active and therefore this aging temperature should not be used. Overall, the combined microstructural and mechanical property methods used in this study confirmed that the observed reduction in strength of ~30-year old solder joints can be accounted for by solder metallurgical aging, i.e. microstructural coarsening.
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| Proceedings Inclusion? |
Undecided |