Effects of green density difference on camber development during the cofiring of a bi-layer glass-based dielectric laminate

Effects of green density difference on camber and stress development during the cofiring of a bi-layer glass-based dielectric laminate have been investigated. A larger shrinkage rate is observed for the tape with a lower green density, toward which camber develops during cofiring. The sintering mismatch stress, which is calculated from the camber development during cofiring, is much less than those of sintering potentials. Similar data are also obtained for the stress calculated using the linear shrinkage rate difference from the dilatometric measurements. The above results account for the absence of defects, such as de-densification, de-bonding and channel cracks in the cofired multilayer laminates.

► This paper deals with camber and stress development of a multilayer low-temperature cofired ceramics, which is one of key factors in manufacturing high-quality, high-yield ceramic modules and devices.
► Camber and stress development during cofiring of LTCC result from densification rate different between different materials or the same material with different packing density.
► Sintering mismatch stress generated during cofiring is calculated using the experimental data of camber rate and linear strain rate difference based upon the viscous analogy for the constitutive equations of a porous sintering compact. Both results are consistent.