Patterning of aluminium metallised PET film using high repetition rate fibre laser

We propose a method for rapid laser isolation of a 12 µm-thick aluminium (Al) metallised polyethylene terephthalate (PET) film. The laser patterning system employed a cost-effective, nanosecond-pulsed master- oscillator power amplifier (MOPA) fibre laser. A dynamic focusing configuration was adopted as a replacement of conventional telecentric lens setup for beam focusing and beam delivery. The ablation process caused thermal removal of Al, and effects of processing parameters on ablated channels’ width, depth, edge quality and electrical isolation were investigated. It was found that a higher deposited laser energy caused kerf width to increase. The chance of electrical isolation also increased with it at a cost of risk to damage surrounding electrode and substrate layers. Based on the findings, a processing recipe was established. Channels with a minimum width of 42 µm could be produced at a scan speed of 900 mm/s without visible collateral damage inflicted to the PET film. Finally, the process was modelled using finite element method and validated against the experimental data.