Creep Properties Assessment by Shear Punch Creep Test and IMC Morphology of Aged Pb-Free Solder Joint/UBM
Abstract
:1. Introduction
2. Experimental Section and Preparation of Test Specimens
2.1. Materials and Preparation of Test Specimens
2.2. Experimental Method and Conditions
3. Result and Discussion
3.1. SPCT Displacement-Time Curve
3.2. Power-Law Relationship
3.3. Monkman-Grant Relationship
3.4. Observation of IMC Behavior
4. Conclusions
- Based on the results of the SEM micro images, the thickness of the IMC increased, and the shape of the IMC morphologies changed from round to needle-like with an increase of the aging time. After isothermal aging (200 and 600 h), the IMC (Cu, Ni)6Sn5 phases and the micro voids were found on the solder joint/Cu substrate interface. This means that the brittleness of the solder increased, thus causing the deterioration of mechanical properties.
- The power-law relationship indicated that the stress exponent (n) and creep properties of solder joints decreased with the increase of aging time, and that the values (n) of Sn-4Ag-0.5Cu solder joints are higher than those of Sn-37Pb solder joints. It can thus be confirmed that the creep properties of Sn-4Ag-0.5Cu solder joints are better than those of conventional Sn-37Pb solder joints.
- The Monkman-Grant relationship shows that the exponent value (m) solder joints are close to 1. It can thus be confirmed that the SPCT method is a reliable method, which can be used to evaluate the creep properties of solder joints.
- Based on our results, the obtained mechanical properties of Pb-free Sn-4Ag-0.5Cu solder joints are greater than those of Sn-37Pb solder joints for all isothermal aging time conditions (0, 200, 600 h). In addition, the melting point temperature of Sn-4Ag-0.5Cu solder joints is similar to that of conventional Sn-37Pb solder joints. Therefore, it is possible to use Pb-free Sn-4Ag-0.5Cu solder joints in electrical applications, rather than Sn-37Pb solder joints.
Author Contributions
Funding
Conflicts of Interest
References
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Solder Joint | Chemical Composition (wt. %) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Sn | Pb | Sb | Cu | Bi | Zn | Fe | Al | As | Cd | Ag | Ni | |
Sn-37Pb | 62–64 | Bal- | 0.10 | 0.03 | 0.03 | 0.002 | 0.02 | 0.002 | 0.03 | 0.002 | 0.002 | 0.01 |
Sn-4Ag-0.5Cu | Bal- | 0.05 | 0.10 | 0.50 | 0.03 | 0.002 | 0.02 | 0.002 | 0.03 | 0.002 | 4.00 | 0.01 |
Material | SPCT Method | ||||
---|---|---|---|---|---|
Solder Joint | Melting Point Temp (°C) | Reflow Condition | SPCT Temp (°C) | Aging Time (h) and Temp (°C) | |
Reflow Temp (°C) | Reflow Time (s) | ||||
Sn-37Pb | 183 | 200 (±5) | 30 | 30 | 0, 200, 600 (At 150 °C) |
Sn-4Ag-0.5Cu | 223 | 240 (±5) |
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Hai, S.; Yu, H.-S. Creep Properties Assessment by Shear Punch Creep Test and IMC Morphology of Aged Pb-Free Solder Joint/UBM. Metals 2019, 9, 209. https://doi.org/10.3390/met9020209
Hai S, Yu H-S. Creep Properties Assessment by Shear Punch Creep Test and IMC Morphology of Aged Pb-Free Solder Joint/UBM. Metals. 2019; 9(2):209. https://doi.org/10.3390/met9020209
Chicago/Turabian StyleHai, Sophal, and Hyo-Sun Yu. 2019. "Creep Properties Assessment by Shear Punch Creep Test and IMC Morphology of Aged Pb-Free Solder Joint/UBM" Metals 9, no. 2: 209. https://doi.org/10.3390/met9020209