Direct-write fabrication of Pb(Nb,Zr,Ti)O(3 d)evices: Influence of paste rheology on print morphology and component properties

Lead niobium zirconate titanate (PNZT) pastes with tailored rheological pro perties have been developed for direct-write fabrication of thick-film capa citor elements in highly integrated, multifunctional electroceramic devices . Such pastes exhibited pseudoplastic behavior with a low shear apparent vi scosity of roughly 1 x 10(6) cP. On aging, the degree of shear thinning and the low shear apparent viscosity decreased. Pastes prepared from as-receiv ed powders attained printable, steady-state viscosities of similar to2 x 10 (5) cP after 50 days of aging. In contrast, pastes prepared from dispersant -coated powders showed no measurable rheological changes after 1 day of agi ng. Square elements were patterned on dense alumina substrates or Teflon sh eets. Leveling behavior as a function of time for single line prints, and t he resulting surface topographies of dried PNZT films were measured by lase r profilometry. PNZT layers sintered at varying temperatures between 950 de grees and 1050 degreesC for 5 h in either air or a lead-rich atmosphere yie lded porous microstructures as revealed by scanning electron microscopy (SE M). Such layers exhibited dielectric constants (K) of 1400-1570 at 1 kHz wi th dissipation factors (D) of less than 4.1%.