Factors influencing rheological characteristics of silver thick film paste and its correlation to multilayer ceramic processing

The rheological properties of silver thick film paste are influenced by the particle size, morphology of silver particles and by the nature of the filler. Rheological properties in-turn influence the multilayer processing parameters and properties. Silver particles, synthesised with gum Arabic (Ag/GA) as the dispersant resulted in agglomerated particles with irregular morphology. Ag/GA-based thick film paste exhibited thixotropic characteristics. Silver powder synthesised with polyvinyl alcohol (Ag/PVA) as the dispersant resulted in well-dispersed, spherical, free-flowing powder with narrow particle size distribution and exhibited pseudoplastic behaviour. The rheological characteristics of Ag/GA-based thick film paste are not influenced by the filler addition. Influence of filler addition is distinctly noted in the rheological characteristics of Ag/PVA-based thick film paste. The homogeneous mixing of Ag/PVA particles with filler and reproducible rheological characteristics of the corresponding thick film paste resulted in excellent printability with good edge-definition and repeatable properties.