On the optimal operational mode of a CNC-controlled laser machine for ablation of thin metal layers on flexible dielectric substrates

Abstract

Scalable and cost-effective microfabrication approaches are highly demanded for manufacturing of RF and millimeterwave circuits such as transmission structures for flexible electronic devices. Flexible electronics play a key role in wearable and wireless technologies applicable in personalized medicine, sensing, energy harvesting, and communication areas. Here we report the results of thin copper films patterns micromachining using nanosecond-pulsed laser on flexible dielectric substrates. Thin copper films were deposited by magnetron sputtering onto 100 μm thick polyimide films that were used as dielectric substrates. Then, patterns were created through film ablation using a CNC laser micromachining system with a 1064 nm ytterbium 8 ns pulse duration fiber laser to chisel away the superfluous material just as it have been done in sculputure for ages. Several regimes of laser micromachining were studied. The most important issue in the laser micromachining of the metal films on the flexible dielectric substrate is flexible substrate thermal damage due to overheating. Optimal regimes of laser micromachining were found that allow to prevent this. These regimes will be used in the future to fabricate flexible transmission lines for RF and millimeter-wave signals. The schematic and design of the transmission line are considered. Results of numerical simulations made by ANSYS HFSS are presented.