Direct gravure printing (DGP) method for printing fine-line electrical circuits on ceramics

The tendency toward higher packing densities and higher frequencies for telecommunication devices based on ceramic technology requires smaller dimensions for electrical wiring. Electrical thick-film circuits for ceramic and LTCC-substrates have, up to now, been printed with screen printing, where the printing lines width limit is about 125 mum in mass production. In this paper, a silicone polymer direct gravure printing (Si-DGP) process has been developed to perform smaller dimensions, down to 20 mum lines width, for electrical circuitry. In the DGP process, the conductor paste is doctored to the grooves of the gravure and then it is pressed against the substrate. The paste is, thus, printed directly onto the substrate from the patterned gravure. The results showed that, using the DGP process, it was possible to print conductor lines down to 20 mum in width. It was also noted that a 100 % transfer of paste from the grooves of the gravure could be obtained with commercial pastes using the silicone polymer gravure. A dried thickness of up to 28 mum was measured for the narrowest lines. Also conductor lines printed by the Si-DGP method were embedded inside LTCC-module.