Comparison of Silver Sources for Silver/Glass Compounds by Multi-Material 3D-Printing

Abstract

Inkjet printing of conductive silver lines on solid or flexible substrates for the fabrication of electronic components has been reported in a variety of ways over more than the last decade. Numerous publications highlight the importance of the silver source for the feasibility of the process as well as the resulting properties of the printed structures. In previous work [1] we reported the first experimental attempt to realize such conductive silver components inside a structure printed with a custom three dimensional powder printer. Aim of this study was to combine the functionality of directly printed functional elements with the geometrical flexibility of powder-based three-dimensional printing. While functionality in the printed glass/metallic compound is achieved in principle, an inhomogeneous microstructure with differentiated silver and glass areas is observed. In this article the silver source for the printing process is varied in order to achieve a homogeneous compound in desired areas. Three different metallic sources were used, namely a diluted screen-printing paste, a silver nitrate solution and silver particles formed by a previously reported polyol process. Ink were formulated from mentioned silver sources and printed with a glass powder. The fabricated samples are investigated in terms of their microstructure evolution and part functionality. The microstructure evolution is discussed in regard to the selected silver source. Additionally, the thermal treatment of the structures is optimized in order to ensure the optimum microstructure and part functionality. The reported experiments present the further development for a unique and novel method for fabricating glass/metal compounds by powder-based three-dimensional printing, allowing for the expansion of the process into novel applications.