The objective of the research is to determine the effects of suspension formulation and rheology on the microstructural uniformity of tape-cast ceramic sheets. The two-dimensional component geometry and simple forming technique will facilitate modeling of the tape-casting process. Alumina-based suspensions will be formulated that contain a bimodal molecular weight (MW) distribution of polymethyl methacrylate, with either broad or narrow polydispersity. The effects of polymer MW and distribution on suspension rheology, particle packing, and the relative ratio of free to adsorbed polymer in the tapes will be investigated. The microscopic distribution of ceramic particles and polymeric constituents as a function of direction will be probed by themogravimetric analysis and scanning electron microscopy as well as by measuring the macroscopic dimensional changes these layers experience during storage, lamination, and densification. Ultimately, processes will be designed which lead to improvements in the microstructural uniformity of tape-cast layers. This knowledge will afford greater dimensional control during multilayer ceramic fabrication which impacts a critical technology--multichip electronic packaging. Tape-casting is a critical process for forming the ceramic substrates for ceramic printed wiring boards and the uniformity of the sheet determines the attainable wiring density.
