Fatigue Life of Sn3.0Ag0.5Cu Solder Alloy Under Combined Cyclic Shear and Constant Tensile/Compressive Loads
| Autor: | Bernard Glasauer, Ian Bernander, Travis F. Dale, Yuvraj Singh, Peng Su, Carol A. Handwerker, Ganesh Subbarayan |
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| Rok vydání: | 2020 |
| Předmět: |
010302 applied physics
Materials science Fatigue testing 02 engineering and technology Cyclic shear 021001 nanoscience & nanotechnology 01 natural sciences Computer Science Applications Electronic Optical and Magnetic Materials Stress (mechanics) Mechanics of Materials 0103 physical sciences Ultimate tensile strength Electrical and Electronic Engineering Composite material 0210 nano-technology Constant (mathematics) Solder alloy |
| Zdroj: | Journal of Electronic Packaging. 142 |
| ISSN: | 1528-9044 1043-7398 |
| DOI: | 10.1115/1.4048109 |
| Popis: | Solder joints in electronic assemblies experience damage due to cyclic thermomechanical loading that eventually leads to fatigue fracture and electrical failure. While solder joints in smaller, die-sized area-array packages largely experience shear fatigue due to thermal expansion mismatch between the component and the substrate, larger area-array packages experience a combination of cyclic shear and axial tensile/compressive loads due to flexure of the substrate. Additionally, on larger processor packages, the attachment of heatsinks further exacerbates the imposed axial loads, as does package warpage. With the increase in size of packages due to 2.5D heterogeneous integration, the above additional axial loads can be significant. Thus, there exists a critical need to understand the impact on fatigue life of solder joints with superposed compressive/tensile loads on the cyclic shear loads. In this paper, we describe a carefully constructed multi-axial microprecision mechanical tester as well as fatigue test results on Sn3.0Ag0.5Cu (SAC305) solder joints subjected to controlled cyclic shear and constant compressive/tensile loads. The tester design allows one to apply cyclic shear loads up to 200 N while maintaining a constant axial load of up to 38 N in tension or compression. The tester is capable of maintaining the axial load to within a tolerance of ±0.5 N during the entirety of fatigue experiment. Carefully constructed test specimens of Sn3.0Ag0.5Cu solder joints were isothermally fatigued under systematically increased compressive and tensile loads imposed on the test specimen subject to repeated loading (R = 0) under lap-shear. In general, the imposition of the superposed compressive load increases the fatigue life of the solder joint compared to application of pure cyclic shear, while the imposition of the superposed tensile load decreases the fatigue life. At larger compressive loads, friction between fractured surfaces is responsible for significant energy dissipation during the cyclic load–unload cycles. |
| Databáze: | OpenAIRE |
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