Characterization and Modeling of Thin Film Interface Strength Considering Mode Mixity

Interfacial delamination is a common cause of failure in microelectronic packages. Characterization and prediction of interface behavior in manufacturing, testing and application conditions is demanded in order to reduce development times and costs of IC packages. In the design processes of microelectronics, possible interface delamination is evaluated by the critical energy release rate to detach the materials. This critical energy release rate can be obtained experimentally using various approaches. However, its measurement is complicated due to the fact that adhesion strength is not only temperature and moisture dependent but also stress state (mode mixity [1]) dependent. This paper describes our efforts on interface characterization as a function of mode dependency. A new test setup is designed and built. It allows transferring two separated loads on a single specimen. The test methodology that is developed in this paper is also able to evaluate the interfacial fracture toughness as function of temperature and moisture. The crack length, necessary for calculation of the energy release rate is measured by means of an optical microscope. Finite element simulation is used to interpret the experimental results and thus to establish the critical energy release rates and mode mixities.