Hyperelastic Property Measurements of Heat-Cured Silicone Adhesives by Cyclic Uniaxial Tensile Test

Abstract

Most of the commonly used linear elastic properties of silicone adhesives cannot precisely represent their material behavior, knowledge of which is crucial to the reliability study of electronic devices. For this reason, in this paper a widely used silicone adhesive, namely Loctite 5404, is chosen for measuring hyperelastic properties via cyclic uniaxial tensile tests. A special sample preparation procedure is developed to avoid the formation of detrimental air bubbles in the samples. Two maximum strain levels, 20% and 40%, are used in the tests. Each test includes five cyclic loadings to produce a stable stress–strain loop. Three orders of magnitude of strain rate changes are studied, and the stress–strain response of the material is found to be strain rate dependent. The measured stress–strain data are imported into Abaqus finite-element software to calibrate the material coefficients of hyperelastic material models (Mooney–Rivlin, Yeoh, Ogden, and van der Waals models). This is the first time that the hyperelastic properties of the studied silicone adhesive are presented. The determined material coefficients can be used directly in finite-element analyses and thus in reliability studies of electronic devices.