Constitutive modeling of solder alloys for drop-impact applications. (December 2016)

• Record Type: Journal Article
• Authors: Wong, E.H.; Chrisp, J.; Selvanayagam, C.S.; Seah, S.K.W.
• Is Part Of: Microelectronics and reliability. Volume 67(2016)
• Page Start: 135
• Page End: 142
• Publication Date: 2016-12
• Subjects: Drop-impact -- Dynamic yield -- Viscoplastic -- Johnson-Cook -- Perzyna; Electronic apparatus and appliances -- Reliability -- Periodicals; Miniature electronic equipment -- Periodicals; Appareils électroniques -- Fiabilité -- Périodiques; Équipement électronique miniaturisé -- Périodiques; Electronic apparatus and appliances -- Reliability; Miniature electronic equipment; Periodicals; 621.3815
• DOI: 10.1016/j.microrel.2016.10.007
• Languages: English
• ISSNs: 0026-2714

Abstract

Abstract: The stress-strain data of four solder alloys - Sn37Pb, Sn1·0Ag0.1Cu, Sn3·5Ag, and Sn3·0Ag0.5Cu – at seven initial strain rates between 0.005 s − 1 to 300 s − 1 have been generated using a combination of mechanical and drop-weight compression tests. Assuming negligible inertia of the test specimen, the stress-strain-strain rate characteristics σ ( ε, ε ̇ ( ε )) of a solder alloy can be readily evaluated from the measured time history of the impact force in a drop-weight compression test. The stress-strain-strain rate characteristics are transformed to the condition of isostrain rate σ ( ε, ε ̇ iso ) while being curve-fitted to the Johnson-Cook and the Pernzya models. The former represents the dynamic-yield model and the latter the viscoplastic model. The quality of the extracted material constants for the Johnson-Cook model are validated by (i) reproducing the impact force-time characteristic of the Sn37Pb solder test specimen using finite element analysis and using the extracted material constants; and (ii) extracting the material constants for the Sn37Pb solder alloy using the inherent optimisation capability of commercial finite element code. Highlights: Technique for characterizing the dynamic stress-strain properties of metals Transformed σ ( ε, ε ̇ ( ε )) to isostrain rate condition σ ( ε, ε ̇ iso ) Extracted material constants for Johnson-Cook and Pernzy models for solder alloys Validated against material constants for Johnson-Cook model using FEA optimisation