Influence of lamination parameters on LTCC shrinkage under unconstrained sintering

LTCC (Low-Temperature Cofired Ceramic) has attracted considerable interest as a material for sensors and microfluidic circuits, for which dimensional accuracy is essential. The irregular shrinkage behaviour of LTCC tapes must be taken into account when designing devices. Furthermore the shrinkage observed in practice can be different than that given by the manufacturers. This study analyses and models with Design of Experiments the shrinkage of DuPont GreenTapeTM 951AX LTCC foils. Unlike most past studies, which concentrated on firing conditions or paste compositions, only the influence of the most obvious lamination parameters is characterised in this paper. A linear model is proposed and the relative importance of the parameters discussed. The most important (lamination pressure and temperature) play a non-negligible role (up to 1% of linear dimension) on shrinkage for a given firing profile. As expected, the more pre-densification the LTCC receives during lamination, the less it shrinks during firing.