Pulsed Fiber Lasers Types and Applications

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2 Pulsed Fiber Lasers Types and Applications IPU - KØbenhavn 13 th March 2012 Dr Jack Gabzdyl Product Line Manager Pulsed Lasers jack.gabzdyl@spilasers.com

3 Today s Presentation Introduction to SPI Introduction to pulsed fiber lasers Marking Micro-machining Case studies Conclusion

4 SPI Lasers Company Overview Specialists in fiber laser technology. Development of highly effective laser solutions. Fiber lasers for industrial macro, micro-machining, marking and medical applications. Internal R&D and production of optical fiber and key components.

5 SPI s Product Portfolio redpower OEM for macro and kw beam source development project. redenergy G4 for marking and pulsed micro-machining 10W-70W redpower R4 for micro-machining up to 500W redenergy Green for micro-machining and specialized marking 8W

6 SPI Markets and Applications SPI s fiber laser applications can be found in a wide range of industries including some of the following: Automotive 2D/3D Cutting Plastic welding Sub 2mm Metal Cutting Night & Day Marking Welding Electronics Medical Battery Technology Chip resistors IC Marking Night and Day Marking Marking Plastic Marking Metal Engraving Drilling Semi-conductor marking Stent Cutting Plastic Welding Precision Cutting Metallic Marking Fine Wire Welding Precision Welding Medical Devices Medical / dermatology / dental Solar Thin Film Processing Thin Film Patterning Solar Scribing Ceramic Marking Silicon Cutting Ceramic Scribing Micro-manufacturing Micro-machining Precision Cutting

7 Nanosecond Lasers Predominantly solid state 1micron sources Rod - Nd:YAG, YVO 4 Disk Yb+:YAG Fiber - Yb+

8 Benefits of ns Fiber Lasers Highly efficient Air cooled Compact Monolithic design No associated cooling issues No need for alignment No maintenance requirement Fit & Forget Technology!

9 Flexible Tool Diverse Applications Images and samples courtesy of: Miyachi Unitek, Electrox, LMCo & Orotig

10 Processing Applications Laser materials processing is governed by: Peak pulse power - which is typically required to overcome processing thresholds. (kw) Pulse energy - which governs the amount of thermal energy available to effect any material processing. (mj) Pulse duration - which impacts the beam material interaction time. (ns) Power Density which reflects the intensity of the laser energy on the substrate. (J/cm 2 ) Beam Quality Energy distribution within the beam (M 2 ) It is a combination of all of these parameters that needs to be considered.

11 Power Typical Pulsed Outputs Increasing pulse frequency results in decreased peak power..but constant Av Power Full pulse length constant typical of a q-switch 20kHz 40kHz 60kHz 80kHz Time

12 Power DM Seed pulse characteristics By decreasing pulse length can optimise peak power at higher rep rates 80kHz 60kHz 40kHz 20kHz

13 Power DM Seed pulse characteristics But each pulse length can operate at any frequency giving greater pulse flexibility. Power/kHz Pulse Length

14 Voltage (V) SM Pulse Characteristics pulsed laser waveforms of SM laser E E E E E E E-07 Time (s) Each trace is a different wave form at PRF0 35kHz, wfm 11 37kHz, wfm 12 39kHz, wfm 13 44kHz, wfm 14 48kHz, wfm 15 51kHz, wfm 16 55kHz, wfm 17 60kHz, wfm 18 63kHz, wfm 19 68kHz, wfm 20 72kHz, wfm 21 80kHz, wfm 22 90kHz, wfm kHz, wfm kHz, wfm kHz, wfm kHz, wfm kHz, wfm 28

15 PulseTune - Waveforms The ability to shorten pulses gives the ability to tune the ratio between pulse energy and peak power These hammers were both made at the same frequency with the same average power at the same marking speed. So what s different????? Left long pulse low peak power incomplete removal of colour anodise Right shorter pulse higher pulse energy complete removal bright white mark

16 Tailored Beam Quality & Pulse Energy The right tool for every job! Series SM RM/HS HM M 2 <1.3 <2 ~3.2 Power 10W / 20W 10W / 12W / 20W 25W / 30W / 40W Key attribute Fine feature Multi purpose Wider lines <25micron 35-80micron >60micron Application Scribing (P1) Fine marking General marking and micro-machining Wide marks deep engrave area/logo

17 Ceramic Drilling Comparison SM HS HM M2 <1.3 M2 <2 M2 <3.4 SM hole is 15% smaller than HS

18 Ceramic scribing comparison Snap and break holes in ceramic SM HS HM M2 <1.3 M2 <2 M2 <3.4 SM hole is 30% deeper than HS

19 Applications- Marking Marking metallics Complex mechanism and material interactions Highly material dependent Black anneal Stainless steel Anodised Aluminium Copper Pipe Colour Marking

20 Aluminium dark marking On clear anodised material conventional mark is to engrave Using short pulses and high khz can create a dark mark Control of parameters can give good contrast control

21 Paint on metal clean pass Removal of paint from aluminium water bottle WF0 pass to remove paint leaves slight residue and rough surface finish WF3 pass at higher speed to clean and give smooth bright finish

22 Applications- Marking (2) Marking non-metallics Complex mechanism and material interactions Highly material dependent Colour change Animal Tag IC Package Key Pad

23 Avoiding Hot Spots Some plastics will just burn Use Fill and eliminate overlap Go Fast using less power per pulse Outline dark and light fill.

24 Semicon marking IC chips Creating a small readable data matrix Using WF0 25kHz can generate mark where each pulse represents a pixel Using WF3 at 250kHZ can generate sharper image with better definition contrast and readability Using SM laser ultra small matrix can be marked 1mm 20W SM 1mm matrix on Silicon

25 Micro-machining

26 Precision Thermal Effects Non Linear effects Pulsed Laser Metallic Processing Melt dominated (hot) Vapour dominated (cold) Optimal Precision??? Cost/W 100ns 10ns 1ns 100ps 10ps 1ps 100fs

27 Precision Thermal Effects Nanosecond Regime Non Linear effects Metallic Processing Melt dominated (hot) Vapour dominated (cold) Optimal Precision??? Cost/W 100ns 10ns 1ns 100ps 10ps 1ps 100fs

28 Laser Ablation - ns lasers Laser pulses Lens One of the issues with process optimization is the interaction of the material with the laser beam. Ejected molten material Recast layer Surface debris Plasma plume Damaged adjacent structure Shock wave Heat affected zone Microcracks Melt zone Heat transfer

29 Single slice formation Laser beam path Hatching step-over Formation of a hatching slice Distance between the centres of neighbouring craters The distance between the craters can be altered by changing the pulse frequency and the scanning speed.

30 Single Slice Formation border cuts laser spot hatching cuts border cut step-over hatching cut step-over controllable distance between border cuts and hatching cuts, possible overlapping

31 Micro-machining strategies Random Hatching Border Cuts Only Random Hatching Only and Border Cuts Material removal strategies have a direct effect on the surface topography and the edge definition.

32 Applications - Engraving Engraving Applications where removal of material is required Complex multi layer processing to achieve optimal results Data matrix Stamp Print Rolls Jewellery ACSYS GmbH LMCo

33 Deep Metallic Engraving 40W HM Capable of deep marking quality not a prime concern Requires short focal length lens and high beam expansion High repetition cleaning pass to improve finish 10mm

34 Deep Engraving - Steel 40W HM High removal 10mm 3 /min or High Quality 4mm 3 /min 13mm high font 0.8mm deep Complex strategy

35 Fast Deep Engraving using WF 0 High removal rate engraving Using just WF 0 Laser rep rate: 40 to 60 khz Hatch angle: rotate by 60 to 90 after every pass Optimise scanner delays to increase removal rate. Issues High heat affected zone Burr on top surface Rough bottom` Ø 3 mm 460 μm deep 18.7 seconds 10.4 mm 3 /min

36 High Quality Deep Engraving Slower, higher quality removal WF 0 high removal but rougher base and perimeter ridge WF 1 lower removal but smoother base, no ridge Use combination of WF 1 and WF 0 for engraving Begin with WF1 (152 khz, 85% P-P overlap) Avoids perimeter ridge Use 6 hatch angles and 2 cleaning hatches Continue with WF0 (60 khz, 90% P-P overlap) Higher removal rate Use 6 hatch angles and 2 cleaning hatches Periodic use of WF5 500kHz for polishing

37 High Quality Deep Engraving For each pass: hatch angles Using WF1 or WF0 Cleaning pass WF5, 500 khz 3 hatch angles Using WF1 or WF0 Deep engraving regime 10 passes WF1 10 passes WF0 (repeat) xnum 10 passes WF1 Cleaning pass WF5, 500 khz

38 Engraving micro ribs Stainless Steel Micro-machining of sharp features 20W pulsed fiber

39 Tooling for µ-injection moulding Freeform structuring of tooling steel Surface roughness Ra ~ 0.85µm Application: mould tool Material: Stavax Laser source: G3 SM 20W Waveform: 22 Pulse length: 90ns DPSS source equivalent Ra 1.02µm Moulded part 3D CAD model Laser milling of steel

40 Cutting with Pulsed Laser The high peak power and power density can achieve excellent results in scanner based multi pass fine cutting Images courtesy of Miyachi Unitek Copper Aluminium Stainless

41 Examples of Scanner Cutting ALN green ceramic 3mm thick cut with 40W HM laser using 6 passes at 50mm/s Brass sheet cut with 20W HS 0.8mm thick in 7min image courtesy of Orotig srl Silver disc 0.55mm thick cut with 20W in 13minutes image courtesy of Orotig srl

42 Cutting is best when kerf is wide All Cuts made at same speed Same number of passes Exact same time per groove All done in 113 seconds

43 Case Study Glassy Carbon Micro-machining

44 Engraving glassy carbon Micro-machining

45 NPL Micro probe

46 GC machining of micro probe

47 GC laser cleaning Before After

48 Embossed replicas on Glass Manufactured from fiber laser processed moulds

49 Summary Pulsed fiber lasers are much more than a marking source... Proven as industrially reliable Fit & Forget technology The flexibility allows their use in a broad range of micromachining applications As a relatively new technology it is still in the development cycle Further innovations will be coming soon...

50 What do you actually need??? COST? PRODUCTIVITY QUALITY

51 HS Summary SPI s PulseTune waveforms expand the application space for marking and materials processing The HS series offers 3-dimensions of pulse flexibility Beam quality PulseTune waveforms CW-1MHz operation