Printing Method for Long Flight Distance by Laser-Induced Forward Transfer

In this study, a new laser-induced forward transfer (LIFT) method that makes it possible to eject high-viscosity inks with the pressure of the ring-shaped vapor bubble (bubble ring) is presented. The flight distance should be [greater than or equal to]500 [micro]m to increase the throughput in case of industrial applications. However, in case of a long gap, the ink is scattered; therefore, good printing quality could not be obtained. We succeeded in printing high-quality droplets even for long flight distances of 500 [micro]m or more. The laser beam was shaped by the beam size and wavefront converters and then transformed into an annular beam. The experiment was conducted when the gap between the donor and receiver substrates was in the range of 200-2000 [micro]m. The landing droplet was microscopically observed to form an almost perfect circle. Our proposed system can be used in various practical applications, including QR code printing. Keywords: LIFT, bubble ring, wavefront converter, droplet, flight distance, viscosity