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The sintering of Low Temperature Co-fired Ceramics prepared from alumoborosilicate
glass- and Al2O3 powders of similar small particle size was studied by dilatometry, heating microscopy,
microstructure analysis, glass- and effective viscosity measurements. The steric effect of
Al3O3 inclusions was studied using a gnon-reactiveh model composite. With increasing Al3O3 volume
fraction (Φ ≤ 0.45), sintering decelerates and its final stage shifts to higher temperature. The
attainable shrinkage is reduced as Al2O3 particle clusters bearing residual pores become more frequent.
The kinetics of sintering could be described formally superposing the weighed contributions
of differentially sized and randomly composed glass-crystal particle clusters and assuming a sintering
rate controlled by the effective matrix viscosity, which increases with Φ and with progressive
wetting of Al2O3 particles during densification. The "reactive" model composite shows significant
dissolution of Al2O3 into the glass, which has two opposed effects on sintering: reducing Φ and increasing
glass viscosity. For the present case (Φ = 0.25), the latter effect dominates and sintering is
retarded by Al2O3 dissolution. Crystallization of wollastonite starts after full densification. Dissolution
of Al2O3 was found to promote the subsequent growth of anorthite.
Sintering of LTCC
(2008)
Low Temperature Co-fired Ceramic materials (LTCC) have attracted growing interest in recent years since they are promising candidates for highly integrated ceramic packaging. This paper surveys materials concepts of related glass ceramic composites (GCC) and discusses unsolved problems and challenges. The densification of GCC based on "viscous sintering" may be affected by steric effects and partial dissolution of dispersed crystal particles, crystallization and phase boundary reactions.