Investigation of interactions between ultrafast laser beams and screen-printed silver nanopaste films

Authors：Shih Feng Tseng; Chia Ho Liao

Source：Applied Surface Science, 2019, 144696.

DOI：10.1016/j.apsusc.2019.144696

• Ultrafast laser
• Silver (Ag) nanopaste films
• Strain sensor
• Single pulse ablation
• Sheet resistance

This study aims to investigate the interaction between ultrafast laser beams and screen-printed silver (Ag) nanopaste films for strain sensors. After single pulse ablation of Ag nanopaste films with a thickness of 4.58 μm, the ablation threshold was approximately 0.2 J/cm2. By increasing single pulse laser fluences from 0.78 J/cm2 to 1.87 J/cm2, the laser-ablated line widths and depths of Ag nanopaste films were ranging from 22 ± 0.1 μm and 4 ± 0.09 μm to 44.8 ± 1.4 μm and 4.2 ± 0.05 μm, respectively. The sheet resistance of laser-processed Ag nanopaste films was measured by a four-point probe instrument. When the single pulse laser fluences set from 4.7 mJ/cm2 to 1.97 J/cm2, the measured sheet resistances near the laser-ablated line edge of 0.5 mm were 59.52 ± 0.76 mΩ/sq and 115.83 ± 6.11 mΩ/sq, respectively. The optimal ultrafast laser processing parameters consisting of the areal laser fluence of 47.4 J/cm2, the laser pulse repetition rate of 300 kHz, the scanning speed of galvanometers of 500 mm/s, and the overlapping rate of laser spots of 96.1% were used to pattern strain sensors with transversal and longitudinal electrode structures on Ag film/glass substrates.