Conference Agenda

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Program for LiM 2021
Micro: Ablation, Drilling and Cutting 2
Wednesday, 23/June/2021:
11:15am - 12:30pm

Session Chair: Lisa Ackermann, Institute of Photonic Technologies (LPT), Germany
Location: Room 3
ICM Ground Floor 125

11:15am - 11:30am

Polymer film processing with a high-power industrial femtosecond laser

Chandra Sekher Reddy Nathala, Victor Matylitsky, Herman Chui

MKS Spectra-Physics

Polymer materials are increasingly important for medical device, flat panel display and microelectronics applications. Due to the high thermal sensitivity of polymers, femtosecond laser processing can minimize heat deposition, and high powers are needed to achieve fast processing. In our work, we present ablation thresholds and cutting speeds for two common polymer materials, polyethylene terephthalate (PET) and polyimide, processed with a 100 W femtosecond laser with single and burst pulses and at infrared and green wavelengths. Cutting speeds were determined for both single-pass and multi-pass strategies. In addition to determining the ablation thresholds and the maximum cutting speed, the processed samples were analyzed for kerf width and heat affected zone (HAZ). The effect of burst mode operation and spot size on cutting speed, kerf width and HAZ were determined. With optimized parameters, high speed, high quality cutting of PET and polyimide films was demonstrated with a high-power femtosecond laser.

11:30am - 11:45am

Roll-to-roll laser processing of flexible devices

Maurice Clair, Christian Scholz, Mandy Gebhardt

3D-Micromac AG, Germany

In the manufacturing of flexible thin-film devices precision, throughput, and machining quality on ever-smaller structures are playing an important role.

The presentation will give a brief overview of different case studies where roll-to-roll (R2R) laser processing achieve new dimensions in terms of precision, quality and process efficiency.

An example application is the ablation of thin-film layers for medical sensors. In this case, the on-the-fly laser ablation takes place by using an excimer laser and mask projection. The layout of the products is adaptable by various projection masks. The high-repetition rate of the excimer laser allows the production of up to 150 sensors per second. Furthermore, thin-film annealing and cutting of metal substrates with ns lasers as well as thin-film patterning and cutting of polymer substrates with ultrashort pulse laser in a R2R process will be discussed.

11:45am - 12:00pm

Combining LPBF and ultrafast laser processing to produce parts with deep microstructures

Manuel Henn, Matthias Buser, Volkher Onuseit, Rudolf Weber, Thomas Graf

Institut für Strahlwerkzeuge IFSW, Germany

Laser Powder Bed Fusion (LPBF) is limited in the achievable accuracy, surface quality and structure size due to its inherent melting process. The achievable structure sizes are mainly dependent on the focal diameter and the grain size of the powder. Smaller structures, especially deep and narrow slits with a width below 100 µm, are still a major challenge.

Combining continuous wave and ultrashort pulsed lasers in the same optical system enables consecutive additive and subtractive processes. This results in a quasi-simultaneous manufacturing process, where the emerging part can be precisely machined with ultrafast laser ablation after each additively added layer.

In the talk the system technology used for the superposition of the lasers as well as the results of the combined additive and subtractive processes for the fabrication of deep and narrow slits in stainless steel parts will be shown.

12:00pm - 12:15pm

Towards in situ monitoring and feedback control of femtosecond laser-induced nanogratings formation in dielectrics

Olivier Bernard1, Andrea Kraxner2, Assim Boukhayma2,3, Ata Golparvar2, Yves Bellouard1, Christian Enz2

1Galatea Lab, École polytechnique fédérale de Lausanne, Rue de la Maladière 71b, CH-2002 Neuchâtel, Switzerland; 2Integrated Circuits Laboratory, École polytechnique fédérale de Lausanne, Rue de la Maladière 71b, CH-2002 Neuchâtel, Switzerland; 3Senbiosys SA, Rue de la Maladière 71c, CH-2000 Neuchâtel, Switzerland

Tightly focused non-ablative femtosecond laser pulses induce a variety of structural modifications in the bulk of dielectrics. Among those, sub-wavelength nanogratings are particularly interesting as a means not only to locally enhance the material etching selectively (and thus, enabling bulk 3D-micro-fabrication), but also for encoding rich information in high-density permanent data storage media. Femtosecond laser-based processes are subject to perturbations, affecting the repeatability and accuracy of the results. To increase the performance of these processes, we explore a feedback method based on direct monitoring of the laser-affected zone (LAZ) using a probe beam. Specifically, we report on the use of weak signals resulting from the interaction of a femtosecond laser probe-beam with the nanogratings index-modulation as objective functions in feedback loop algorithms.