The origin of dimensional anisotropy and tape movement is studied using rheological techniques and in situ stress measurements. Rheological properties of tape casting suspensions are characterized to probe their relaxation behavior. Stress measurements based on a laser interferometry technique are carried out on tape-cast layers of varying thickness and composition. Our goal is to develop a fundamental understanding of property evolution during drying of these complex colloidal systems.

The structure and chemistry of metal-polymer interfaces are being studied using TEM, RBS, x-ray photoelectron spectroscopy, secondary ion mass spectrometry, and a number of other methods. The system being studied is Cu-polyimide because of its interest to the semiconductor packaging industry. We are interested in how the metal atoms bond to the components of the polyimide, what the nature of the interdiffusion of the metal and polyimide is, and the strength of the bonding across the metal-polymer interface. These processes can be studied on an atomic scale with the techniques used, and general characteristics of these interfaces can be developed.

The techniques of in situ TEM deformation and hot-stage microscopy are being used to study the interaction of dislocations with grain boundaries, the operation of grain boundary dislocation sources, and the interaction of mobile grain boundaries with obstacles such as precipi- tates. These studies are being undertaken to provide an understanding of the physical processes controlling grain boundary cavitation, grain boundary sliding, grain boundary dislocation interactions, and grain nucleation at precipitates.