The current transparent conductive film market is dominated by expensive and fragile Indium-tin oxide electrodes, also known as ITO. However, ITO is made from the rare metal Indium. It results in a high-cost and brittle technology. There is a huge demand for alternative technologies to the ITO transparent electrode. New materials like carbon nanotubes, silver nanowires are still in the research stage and expensive as well. Another alternative could be a metallic mesh with metal wires less than 5 μm in diameter to be invisible but still electro-conductive. We propose our Selective Surface Activation Induced by Laser (SSAIL) technology which utilises laser writing and electroless copper plating. SSAIL technology allows forming electrically conductive circuit tracks on various dielectric surfaces. SSAIL consists of four main steps: 1) laser surface excitation and modification; 2) chemical activation in a catalytic solution; 3) rinsing; 4) electroless autocatalytic deposition of copper [1; 2]. The method technology can be applied on transparent dielectric materials – glass, fused silica or transparent polymers like Polyethylene terephthalate (PET) (Fig 1 a). In this study, we present metal mesh formation on transparent and flexible PET. Results of the experiment disclose deposited electrode properties (dimension (width, thickness) and adhesion to substrate) dependence on laser modification and chemical treatment steps. Finally, bending tests are performed to check the mechanical resistance of the metal mesh structure. Originally, the picosecond laser is used for the initial step; however, the picosecond ranged pulse duration provides undesired thermal effects, thus limiting the formation of very narrow structures.

[1] K. Ratautas, A. Jagminienė, I Stankevičienė, E. Norkus, G. Račiukaitis, Laser-assisted selective copper deposition on commercial PA6 by catalytic electroless plating – process and activation mechanism, Appl. Surf. Sci., 470, 405-410, (2019)
[2] K. Ratautas, A. Jagminienė, I. Stankevičienė, M. Sadauskas, E. Norkus, G. Račiukaitis, Evaluation and Optimisation of the SSAIL Method for Laser-Assisted Selective Electroless Copper Deposition on Dielectrics, Results Phys., 16, 102943, (2020)