Mechanical Behavior and Constitutive Model Characterization of Optically Clear Adhesive in Flexible Devices

Abstract

Optically clear adhesive (OCA) has been widely used in flexible devices, where wavy stripes that cause troublesome long-term reliability problems often occur. The complex mechanical behavior of OCA should be studied, as it is related to the aforementioned problems. Therefore, it is necessary to establish reasonable mechanical constitutive models for deformation and stress control. In this work, hyperelastic and viscoelastic mechanical tests were carried out systematically and relative constitutive models of OCA material were established. We found that temperature has a great influence on OCA’s mechanical properties. The stress and modulus both decreased rapidly as the temperature increased. In the static viscoelasticity test, the initial stress at 85 °C was only 12.6 kPa, 57.4% lower than the initial stress at 30 °C. However, in the dynamic test, the storage modulus monotonically decreased from 1666.3 MPa to 0.6628 MPa as the temperature rose, and the decline rate reached the maximum near the glass transition temperature (Tg = 0 °C). The test data and constitutive models can be used as design references in the manufacturing process, as well as for product reliability evaluation.

Effect of Temperature and Humidity on Mechanical Properties and Constitutive Modeling of Pressure- Sensitive Adhesives

“…The Mooney-Rivlin and Neo-Hookean models, displaying more linear fitting curves, diverge significantly from the experimental findings. Consistent with the findings of previous research by Zhang 18 , it is observed that the Mooney-Rivlin and Neo-Hookean models approximate linear responses and are suitable for describing small to moderate deformations. On the contrary, the third-order Ogden model offers heightened flexibility and affords superior fitting accuracy, thereby adeptly representing the substantial deformations encountered in PSAs.…”

“…The elastic potential in these models is typically expressed through the strain invariants or the principal stretches 15 . Prominent examples of such models include Neo-Hookean, Mooney-Rivlin, Yeoh, and Ogden models, which are extensively employed in the field [16][17][18] .…”

Effect of temperature and humidity on mechanical properties and constitutive modeling of pressure-sensitive adhesives

“…For the calibration of the viscoelastic model of PSAs, one effective method involves conducting dynamic mechanical analysis tests. These tests generate master curves that depict the storage and loss moduli of the PSAs, crucial for calibrating the Prony series 18 . An alternative method is to use relaxation or creep test data, obtained under various strain rates and temperatures, for Prony series calibration.…”

Experimental study on the constitutive model of optically clear adhesive films under rapid loading

“…[24][25][26][27] These characteristic behaviors of OCA are difficult to describe with the conventional elastic and hyperelastic models, and they are rarely mentioned in existing studies. To simplify and facilitate stress analysis of structures containing OCA, there is already a lot of literature adopting isotropic linear-elastic models [28][29][30][31] or incompressible hyperelastic models [11][12][13][32][33][34] for OCA, whereas few studies have systematically investigated its inherent loading rate dependence, anisotropy and certain compressibility under rapid loading.…”