Investigation of effect of temperature and strain rate on mechanical properties of underfill material by use of microtensile specimens

In this paper. a testing methodology was developed for microtensile specimens. With the methodology. the effect of testing conditions on the mechanical properties of an underfill material was investigated at various strain rates from 10(-5) to 10(-1)/s over a wide temperature range from -40 to 240 degreesC. It was found that the testing conditions and. in particular. the testing temperature affect the measured properties greatly, The relationship between the testing temperature and the mechanical properties exhibits a nonlinear characteristic and shows three trends. In particular. the mechanical properties were found to have a sharp change around the glass transition temperature (T-g). In contrast. the mechanical properties were found to have an approximately linear relationship with the logarithmic strain rate. The fracture surfaces of the tested specimens were analyzed by scanning electron microscope (SEM) and the fracture features were employed to explain the experimental observations. (C) 2002 Elsevier Science Ltd. All rights reserved.