Metallic Powders for Composite Inks: Formulation, Application, and Characterization

In this study, the suitability of four metal powders and one alloy powder for use in composite inks was investigated on the basis of the contribution by each metallic powder to the formulation, printability, hardness, rheology, conductivity and thermal properties of the inks. The effects of the binder chemistry, the composition of the inks and the application conditions on the rheological, electrical, thermal properties of the inks were investigated. The results show controlled film deposition could be achieved by using a screen printing technique. The relationship between the viscosities of the inks with an increase in temperature depends on themetal powder used in formulation and on the polymeric binder chosen. Those inks that were based on the poly(vinylpyrrolidine)-co-stypre (PVS-co-S) have shown an increase in viscosity as the flow temperature was increased above 60 oC. The resistance properties of these inks depend on the temperature at which the inks were dried. This can allow for a control on the flow of electrons in the ink prints and a balance between print hardnessand electrical properties to be achieved. Of the three substrates that were used in the studies, the inks applied onto the tinplated steel and onto the PET substrate showed signs of inkdelamination, after drying. However, no such delamination was encountered from the inks that were applied onto the paperboard substrate.

Keywords: Metal powder; ink; conductivity; hardness; rheology; analysis.