Inkjet Printing of Multilayer Capacitors

Capacitors are widely used passive components. Taking account of micro hybrid circuits, printed capacitors are desirable. However, today's screen printing technology results in very low specific capacitance per area, thus SMD components are usually preferred. In order to achieve a higher specific capacitance, simple plate capacitors are stacked to form multilayer components. Maskless inkjet printing allows for realization of such structures. To keep the process simple, in-between sintering is avoided; the entire component is cofired in one final step. To define the geometry of the components, the general processability of the used material combination is first examined. Among other things, the extent to which the structures can be decreased in size without affecting their functionality is determined. In further experiments, the effects of thermal expansion and sinter shrinkage are analyzed. To create multilayer capacitors, a second step takes place in which the design is completed. Vias are embedded to bypass the dielectric layer or the opposing electrode. When increasing the height of the structure, the aspect ratio that can be achieved by the printing process is considered.