Trumpf Maschinen AG Taper-free laser cutting of micromechanical components CTI Micro and Nano Event Janko AUERSWALD Head of Application Center Basel, June 30, 2016
Outline 1) Motivation 2) Taper angle optimization with conventional USP laser processes (Results CTI project PICOFAB) 3) Impact on TRUMPF Maschinen AG Baar 2
Properties of lasers Photon oscillation in phase Directed light propagation Narrow wavelength range ( monochromatic ) Traditional laser: too hot for micro-fabrication!!!
Advantages of ultra-short pulse (USP) lasers Cold machining: no heat-affected zone High edge and ablation surface quality No deformation or cracks USP laser Hot laser http://www.industrial-lasers.com/articles/print/volume-29/issue-5/features/femtosecond-laser-processing-of-metal-and-plastics-in-the-medical-device-industry.html
Why ultra-short pulses? Pico- and Femtoseconds Short pulses (ms, ns) Ultra-short pulses (ps, fs) Liquid phase, burr Heat-affected zone HAZ Limited precision High quality High precision C. Momma, B.N. Chichkov, S. Nolte, F. von Alvensleben, A. Tünnermann, H. Welling, B. Wellegehausen, Short-pulse laser ablation of solid targets, Opt. Commun. 129, 134 (1996) 5
USP: All materials possible Metals Ceramics Glasses Sapphire Diamond Polymers Composites Biological tissue,
Motivation Requirements of CH target market watch industry High quality of edges Low roughness Shape tolerances of a few micrometers Large material and design variety Source: http://static.piaget.com/pub/media/cache/img_piaget/photorect/21897/900/16x9/v11.jpg 7
Motivation Requirements of CH target market medical industry Biocompatible materials (stainless steel, Nitinol, titanium, ceramics) Clean edges Shape tolerances somewhat relaxed (10 microns or more) Corrosion-resistant even markings with good contrast 8
Outline 1) Motivation 2) Taper angle optimization with conventional USP laser processes (Results CTI project PICOFAB) 3) Impact on TRUMPF Maschinen AG Baar 9
Project partners PICOFAB CSEM Alpnach Berner FH Burgdorf, Group Prof. Neuenschwander TRUMPF Maschinen AG, Baar 10
Results CSEM TruMicro 5350 UV (343nm), scanner cutting (hatch and equidistances) Roughness values: R a : arithmethic average R q : quadratic average (rms), more sensitive to scratches Achieved results: Material Ra [nm] Rq [nm] Taper [ ] Silicon 150-200 200 > 86 Si3N4 250 300 > 87 Sapphire 80-150 100-200 > 85 11
CSEM: TruMicro 5350 (343 nm), scanner f = 103 mm Escapement wheel in ceramics, silicon and sapphire 12
Silicon surface post-treatment Improvement of surface roughness Proprietary process at CSEM, patented 13
TRUMPF: TruMicro 5250, 515 nm Fixed optics cutting with wobbling scanner Achieved results: Material Ra [nm] Rq [nm] Taper [ ] Silicon 170 220 > 88 Si 3 N 4 250 330 > 88 Sapphire 330 400 > 87 14
Resultate WP1 Multifunction demonstrator in Si 3 N 4 15
TruMicro 5250, 515 nm Multifunction demonstrator in silicon 16
TruMicro 5250, 515 nm Multifunction demonstrator in sapphire 17
Results BFH: TimeBandwidth Fuego, 1064 nm Scanner with cross hatch Burst Mode: no improvement of cutting quality Achieved results: Material Ra [nm] Rq [nm] Taper [ ] Silizcon 380 460 > 88 Si 3 N 4 320 400 > 87 Sapphire - - - 18
Results BFH TimeBandwidth Fuego, 1064 nm Silicon Silicon Nitride Great theoretical contribution to Understanding the process taper angle formation Finding the optimal fluence (Neuenschwander-model) 19
Summary CTI project PICOFAB Conventional USP cutting without trepanation Ultra-hard and brittle materials Ceramics, silicon, sapphire Taper of 88 achievable with TruMicro, fix optics and wobbling Rougness Ra of 0.3 µm or better achievable Some trepanning tests made in CTI project, but no satisfying results. Therefore, R&D activities at TRUMPF go on. 20
Outline 1) Motivation 2) Taper angle optimization with conventional USP laser processes (Results CTI project PICOFAB) 3) Impact on TRUMPF Maschinen AG Baar R&D Trepanning optics tests for the new TruLaser Cell 2000 No beam inclination Static beam inclination Dynamic trepanation cutting TOP Cleave optics configuration for transparent materials 21
TruMicro 5050 with Scanlab precsys optics 1-beam reducer, 2-circular polarizer, 3-SCANLAB precsys, 5-axis sub system, 4-sample fixation, 5-x-y-z-stage, 6-mirror 22
Some test equipment characteristics Laser: Trumpf TruMicro 5050 λ = 1030 nm τ p = 6 ps E p,max = 250 μj M 2 = 1.2 Optics: precsys Beam inclination: -7.5 bis 7.5 5-axes galvo-system Quelle: http://www.ch.trumpf.com/de/produkte/lasertechnik/produkte/festkoerperlaser/kurz-und-ultrakurzpulslaser/trumicro-serie-5000.html (30.10.2015) 23
No beam inclination Finding good base parameters for optimal edge profile 24
Influence of laser process parameters on taper angle Pulse energy, defocus, (cutting speed pulse overlap, repetition rate) 25
Influence of laser process parameters on taper angle Brass cutting, 0.2 mm thickness Pulse energy increase better taper angle Defocus worse taper angle Straight edges of good quality < 1 taper: 33 µj pulse energy, 0 mm defocus, 0.2 mm/s cutting speed and 400 khz repetition rate Base parameter for the following tests with static beam inclination 26
Static beam inclination Would allow cutting of 0 taper edges with sharp angles 27
Cutting with static beam inclination No trepanation, just static beam inclination - Would allow sharp angles without radius of trepanation - 33 µj pulse energy, 0 mm defocus, 0.2 mm/s cutting speed, 400 khz repetition rate 28
Mittelwert [ ] Mittelwert [ ] Mittelwert [ ] Mittelwert [ ] Results static beam inclination Beam inclination vs. achieved taper angle: linear correlation -1 Base parameters Basisparametersatz: Mittelwert Taperwinkel 1 Lower pulse energy Pulsenergie 16 J: Mittelwert Taperwinkel -2 0-3 -1-2 -4-3 -5-4 -6-5 -6-7 -7-8 -8-9 0 1 2 3 4 5 6 7 8 Anstellwinkel [ ] Higher pulse energy Pulsenergie 90 J: Mittelwert Taperwinkel 1 0-1 -2-3 -4-5 -6-7 -8-9 5 4 3 2 1 0-1 -2-3 -4 0 1 2 3 4 5 6 7 8 Anstellwinkel [ ] Grosser Defokus Defokus 1mm: Mittelwert Taperwinkel -9 0 1 2 3 4 5 6 7 8 Anstellwinkel [ ] -5 0 1 2 3 4 5 6 7 8 Anstellwinkel [ ] 29
Dynamic trepanation cutting Compensated taper angle in all directions, but trepanning radius 30
TruMicro 5050 with precsys optics: Dynamic trepanation cutting Completely compensated taper angle, trepanning radius ca. 70 µm Brass 0.2 mm, ca. 10 min per piece, there is still potential for lower cutting time 31
TruMicro 5070 with trepanning optics SLH 200 Steinmeyer Low-cost trepanning optics Prism for beam shift Wedge for beam inclination 32
TruMicro 5070 with Steinmeyer trepanning optics SLH 200 Durnico 0.2 mm, ca. 10 min cutting time; trepanning radius a bit too large 33
Transparent materials TOP Cleave Optics Taper of 0 possible Material modification by beam shaping Separation along the material modification by: Inner stress (e.g. chemically hardened glass) Thermal stress Mechanical stress Chemical etching 34
TOP Cleave Optik 35
TruLaser Cell 2000 for future markets and trends Complete turn-key solution USP laser, optics, machine Application support and service Flexibility Interchangeable optics Future upgrades laser & optics possible High precision 36
Summary and outlook Parameter optimization for conventional USP processes results already in taper angles of 2 in brittle materials and <1 for metals Trepanning optics allow for tapers of 0 for cutting TOP Cleave optics lead to taper of 0 in transparent materials Beam inclination using axes kinematics? 37
Thank you for your kind attention! Questions??? 38