Electrophotographic Printing of RFID Antenna Coils on Cofired and Postfired Ceramics

Abstract

Digitally printed electronics are a major field of activity in research and industrial applications nowadays, especially in thick-film technology. Within the last decade great progress has been made in print electronics toward the goal of supplementing or replacing the established screen printing technology. The advantage of digital printing is its capability for rapid production without any layout-specific tools (i.e., screens). This highly flexible production method is especially applicable for prototyping and small series productions. Electrophotography, commonly known as laser printing, has been considered very rarely as a method for digital printing of electronic circuits. It is a completely solvent-free method with high speeds and a high potential for precision. At Helmut Schmidt University, electrophotography is being developed as an alternative method to print silver lines as a basis for a conductive layout. Following the publication of the first set of conductive silver lines to be printed, this paper covers the development from initial conductivity to a functional circuit element. Deficits in toner transfer to tape are examined and a more effective transfer method is established. Furthermore, the used silver toner is improved, and its performance is tested regarding the desired application. Silver lines are printed on green tape and sintered in a cofiring process, as well as on ceramic using a postfiring process. After reaching a certain level of quality, a set of functional RFID antenna coils is printed that proves the capability of the process to create a conductive layout.