Abstract
Constrained densification during cofiring of LTCC multi-layers results in localized tensile stresses, which can generate defects (crack, delamination or voids) in the final products. The mismatch stresses can be predicted if the densification kinetics and constitutive parameters of the sintering constitutes are known. In this work, sinter-forging experiments were performed on cylindrical powder compacts of the widely used LTCC material DuPont 951 A at temperatures of 700 - 760oC and under 0 - 30N. The instantaneous axial and radial strains were measured simultaneously during isothermal sintering. The unaxial viscosity was analyzed as functions of density and temperature. The viscosity increased exponentially with density and decreased with increasing temperature, which agreed well with theoretical prediction. The intrinsic sintering stress was also calculated as a function of density and compared with theoretical models.
