펨토초 레이저를 이용한 OLED용 Shadow MaskInvar 합금의 어블레이션

Abstract

Femtosecond laser ablation of the Invar alloy and hole drilling for a shadow mask are studied. We used a regenerative amplified Ti-sapphire laser with a 1kHz repetition rate, 184fs pulse duration and 785nm wavelength. Femtosecond laser pulse was irradiated on the Invar alloy with air blowing at the condition of various laser peak power. An ablation characteristic of the Invar alloy was appeared non-linear at 125J/cm2 of energy fluence. For the application to a shadow mask, the hole drilling of the Invar alloy with the cross section of a trapezoidal shape was investigated. The ablated micro-holes were characterized using an atomic force microscopy(AFM). The optimal condition of hole pattern for a shadow mask was 4㎛ z-axis feed rate, 0.2mm/s circular velocity, 26.4J laser peak power. With the optimal processing condition, the fine circular hole shape without burr and thermal damage was achieved. Using the femtoseocnd laser system, it demonstrates excellent tool for the Invar alloy micro-hole drilling without heat effects and poor edge.