Abstract
The differences of the mechanical properties of underfill influenced in operating on several temperatures and strain rate level was investigated. As to the moisture and the creep effect on underfill was also studied to fit some suit model by experimental data.It was observed that the fracture stress is higher at a faster strain rate or at a low temperature level, but the fracture strain is on the opposite.The coefficient of moisture diffusion is not always keeping in a constant on the whole progress but is relative to concentration. The creep model is also found by a hyperbolic sine type power law.