Cohesive Zone Modeling

Interface Parameter

Adhesion strength calculations rely on the definition of critical energy release rates and peak traction values. An interface parameter provides the mathematical framework to describe how micro-cracks coalesce into a macroscopic fracture. During thermal cycling simulations, the model tracks the degradation of bonding stiffness as the assembly undergoes strain.

These inputs are typically derived from double cantilever beam tests or lap shear measurements conducted on specific laminate combinations.

Delamination Prediction

Reliability assessments of high density interconnects benefit from the ability to pinpoint where pad cratering or interfacial shearing might occur. Accurate delamination prediction results from the successful integration of plastic deformation and cohesive failure modes. If the traction levels remain below the threshold, the bonded surfaces stay intact.

Once the damage variable reaches unity, the model removes the load carrying capacity of the element to signify a physical break.