Reliability study of an epoxy-bonded laser-to-fiber assembly

A procedure-has been established to evaluate the reliability of different designs for an epoxy-bonded laser-to-fiber assembly. The procedure includes: (1) epoxy characterization to select right materials and curing schedules, (2) bonding strength test to define failure criteria at interfaces, and (3) finite element modeling to choose the designs with acceptable stresses at interfaces. An epoxy material has proven to have excellent thermal stability. The bonding shear strength for epoxy-to-steel adhesion was measured to be 20 Mpa. With this criterion, a finite element model has been developed and verified for a reference case using an existing product with known reliability. The model was then used for a parametric study that identified epoxy thickness and Young's modulus as critical parameters for reliable connections. The procedure can reduce R&D costs to quickly explore different design concepts with minimum experimental evaluation.