Low-stress creep deformation in two opto-electronic glass-epoxy joints: Part I – adhesive creep data

Abstract This two-part paper presents measurements and modelling of creep deformation at relatively low stress of two epoxy adhesives used in opto-electronic applications, one having a relatively high modulus and the other a low modulus. Part I describes the bulk tensile creep tests at various temperatures (75–95 °C) and stress levels representative of those in opto-electronic devices. A novel laser-based method of non-contact creep strain measurement was used to eliminate errors associated with adhesive specimen contact. The high modulus epoxy, tested at stress levels between 5 and 20 MPa, displayed non-linear behavior at high stress levels but was linear over the range of interest. The low modulus adhesive, tested between 0.25 and 0.5 MPa, was linearly viscoelastic over the full range of tested stress levels. Part II assesses the accuracy of finite element models to predict the creep deformation in two different glass-epoxy joints designed to represent stress states in some opto-electronic applications.