Laser direct Cu patterning utilizing a commercially available low-cost 3D printer

Abstract

This study evaluated an inexpensive 3D printer (below 1000 USD) as a cost effective laser direct writing machine. This printer was applied to patterning copper (Cu) electrodes along with characterizing laser modules, such as the power stability of the laser, scan speed, pattern width against laser power, and position precision of the pattern. The laser power, controlled by a pulse width modulation signal, fluctuated by approximately 7 % and decreased by 2.1 % during the measurement period. After multiple laser scanning, the positional stability according to the thickness of the patterned Cu line showed a difference of up to 3.5 μm at the center of the line pattern. Depending on the laser power, line defects appearing at the center of the Cu patterns were observed at the focal length of the laser and disappeared at longer or shorter focal lengths. As the laser power was increased from 6.3 % to 100 %, the width of the patterned Cu lines increased from 22 to 246 μm. This appears to be due to the light scattering of the Cu crystals that form early when the laser is incident. A 143 nm thick 1 cm2 Cu pattern exhibited a resistance of 2.6 × 10−5 Ω·cm. Because this method uses a 3D printer that can control the z-height during laser processing, a Cu pattern-actuated LED on a three-dimensional glass surface was demonstrated using a set of experimental conditions based on the results.