Micromachining of Invar with 784 Beams Using 1.3 ps Laser Source at 515 nm.

Petr Hauschwitz,Bohumil Stoklasa,Jan Brajer,Martin Duda,Hana Turčičová,Michael Písařík,Jiří Kuchařík,Antonio Lucianetti,Danijela Rostohar,Tomáš Mocek

doi:10.3390/ma13132962

Abstract

To fulfil the requirements for high-resolution organic light-emitting diode (OLED) displays, precise and high-quality micrometer-scale patterns have to be fabricated inside metal shadow masks. Invar has been selected for this application due to its unique properties, especially a low coefficient of thermal expansion. In this study, a novel cost-efficient method of multi-beam micromachining of invar will be introduced. The combination of a Meopta beam splitting, focusing and monitoring module with a galvanometer scanner and HiLASE high-energy pulse laser system emitting ultrashort pulses at 515 nm allows drilling and cutting of invar foil with 784 beams at once with high precision and almost no thermal effects and heat-affected zone, thus significantly improving the throughput and efficiency.

Highlights

Invar is a Fe–Ni class alloy with unique properties such as excellent strength, impact toughness, processability and a low coefficient of thermal expansion [1]
Invar (FeNi36) foils provided by Goodfellow GmbH (Friedberg, Germany) with a thickness of 20 μm and dimensions of 50 × 50 mm were used as received (Ra~0.07 μm)
Perla laser system from HiLASE (Dolni Brezany, Czech Republic), equipped with second harmonic generation module emitting at wavelength of 515 nm, with pulse duration of 1.3 ps, beam quality factor

Summary

Introduction

Invar is a Fe–Ni class alloy with unique properties such as excellent strength, impact toughness, processability and a low coefficient of thermal expansion [1]. Those properties are making invar very attractive for various industrial applications including bi-metal applications, storage tanks of liquified natural gas, and shadow masks for production of organic light-emitting diodes (OLED) [2]. Chemical etching is nowadays a common microfabrication method for production of OLED shadow mask [2]. It is a complicated multi-step process generally composed of coating, cleaning, exposure and an etching process with no control over the taper angle. It is difficult to fabricate a pattern smaller than the material thickness due to isotropic manner of chemical etching and reach the high resolution required for future virtual reality displays [5,6]

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Conclusion