Laser Printing of Conductive Silver Lines

Digital printing of functional electronic devices is a major field of research and developments nowadays. Among others, progress is made to replace or supplement thick-film screen-printing technology by inkjet printing.Inkjet printing is already a very developed technology to print passive elements of thick-film electronics. In addition to inkjet, a new approach of printing functional elements is launched at the Institute of Automation Technology of the Helmut Schmidt University / University of the Federal Armed Forces Hamburg (HSU). Electrophotography is a very promising way to print conductive and non-conductive thick-film elements. It offers a completely solvent-free method with high printing speed and a high potential regarding precision.At HSU, a prototype printer is used to print conductor lines on LTCC tape. The corresponding toner is based on conductive silver powder. The approach aims for achieving a complete, conductive layout after firing. The parameters of the printer and its construction are optimized, to gain necessary thickness of lines without losing their sharpness. Several silver toners are utilized and compared. As a result, conductive silver lines are successfully printed and improved in density and thickness.