Laser processes and equipment

Laser processes

More examples of laser processes at Production Engineering YouTube channel

Laser ablation and thin film removal

Laser ablation is the process of removing material from a solid surface by irradiating it with a laser beam. Usually, laser ablation refers to removing material with a short pulsed laser. The name laser ablation is used generally when talking about laser-material interaction, vaporization, micromachining, or thin film removal. Laser thin film removal is one of the most studied fields in the Department of Production Engineering. Materials, such as Ag, ATO, Au, Cu, ITO, Mo, TCO, ZnO, GICS, TiN, and dielectric films, are in focus. Substrates can be for example glass, PET, or PI.

Picosecond fiberlaser used in these tests
LD-10 laser workstation used in these tests

For more information, please contact: Assi Hansen

Laser thin film removal of ITO layer

Glass-glass laser welding

Wafer bonding has increasingly become a key technology for materials integration in various areas of MEMS, microfluidic devices, biomedicals, optoelectronics, hermetic sealing and encapsulation. Glass has a lot of potential in these applications due to its excellent optical, mechanical, electrical and chemical properties. A number of glass-glass direct bonding techniques, including low temperature and high temperature bonding, have been extensively studied and developed. One of the promising bonding techniques is laser welding which allows low heat input, small and selective bonding geometries, low influence on pre-processed wafers, enclosed components and different material combinations.

Picosecond fiberlaser used in these tests
LD-10 laser workstation used in these tests

For more information, please contact: Assi Hansen

Glass-glass laser welded chip

Laser welded chip after cutout

Laser scribing

Traditionally, diamond saw dicing has been used for device separation. However, the kerf width is limited by the thickness and fragility of the dicing blade. In addition, substrate materials can be brittle and fracture easily. Laser scribing is a process for making a groove or line to weaken the structure so that it can be mechanically broken. Scribing brittle materials can be for example photovoltaics, glass, or sapphire.

Picosecond fiberlaser used in these tests
LD-10 laser workstation used in these tests

For more information, please contact: Assi Hansen

Laser scribing of glass

Silicon-glass welding

The excellent mechanical strength of silicon combined with the electrical insulation, chemical durability, and optical transparency of glass makes the silicon-glass couple the most employed material combination in the assembly of sensors and micro system components as well as in the assembly of micro fluidic parts with biological components for biological assays. Laser radiation is transmitted through the glass part and absorbed onto the silicon surface joining the parts together. The main advantages of this technology in comparison to the widely used anodic bonding process are: low heat input, small and selective bonding geometries, low influence on pre-processed wafers and enclosed components.

Picosecond fiberlaser used in Silicon-glass welding
LD-10 laser workstation used in Silicon-glass welding
Fast linear axis workstation used in Silicon-glass welding

For more information, please contact: Assi Hansen

Si-glass laser welded grid

Si-glass laser welded chips

Laser sintering of nanoparticles

Laser sintering of nanoparticle ink is used e.g. in printed electronics. Laser is utilized for heating ink material to the sintering temperature. In laser sintering energy of beam evaporates ink additives and agglomerate nanoparticles into e.g. conducting line. Laser sintering is a selective sintering method, which offers fast process and reliable sintering result.

Laser workstation used for sintering of nanoparticles

For more information, please contact: Tero Kumpulainen

Lasersintered trace, width 200µm

Lasersintered traces on Kapton

Laser drilling

Laser drilling enables manufacturing of holes from small to large with high speed. Laser drilling can be made holes that have large depth to diameter ratio. There are several methods to implement drilling, such as helical drilling, percussion, single pulse, trepanning and micro machining.

Green/IR 15 W pulse laser used for this process.

For more information, please contact: Tero Kumpulainen

Laserdrilled holes on brass

Percussion drilled 300µm holes

Laser cutting

Lasers can be used to carry out various different cutting tasks. Depending on the power, wavelenght and beam interaction time, laser can cut virtually any material. Department of Production Engineering is focusing mainly on microscale cutting processes using solid state lasers.

Laser cutting with high brigthness lasers has many advantages compared to mechanical cutting processes like speed, accuracy, quality, just to name a few.

Fiber laser module used for cutting of thin metal foils.

For more information, please contact: Jorma Vihinen

Lasercut shapes in 0,2mm steel

Laser cutting

Laser marking

Laser marking is a method that can be used for various different materials. Used marking processes vary based on the material to be marked: Controlled surface layer removal of anidozed aluminium, annealing colors of stainless steel or titanium, engraving of steel, foaming or color changing of plastics, just to name a few.

Laser markings can be done with various different CW and pulsed lasers, depending on the process needed. Common advantages to all laser marking processes are for example speed, accuracy, flexibility and versatility.

20W Fiber laser used for marking
Scanner workstation used for marking

For more information, please contact: Tero Kumpulainen

Datamatrix on stainless steel

Lasermarking by paint removal

Laser transmission welding of plastics

Laser transmission welding of plastics is accurate welding technique, which enables hidden joints with a minimum of influence to the components. In the welding process the laser beam travels through the optically transparent upper joining partner and absorbs to the lower joining partner. Through the heat conduction the materials melt from the welding area and as they are cooled down, the durable joint is formed. Laser welding of plastics is adjustable for both mass production and small series of plastic parts.

20W Fiber laser used for this process
300W Diode laser used for this process
Laser transmission welding of plastic microfluidic chip (video)

For more information, please contact: Jussi Halme

Laser welding of microfluidic chip

Components of microfluidic chip

Laser cladding

The laser cladding technique can produce high quality coatings, with minimal dilution, distortion and good surface quality. The deposited material can be transferred to the substrate by several methods: powder injection, pre-placed powder on the substrate or by wire feeding. The laser cladding by coaxial powder feeding has been demonstrated to be the most effective method.

6kW HPDL used for this process
Axially symmetric diode laser used for this process

For more information, please contact: Henri Pajukoski

Laser cladding with Nd-YAG laser

Laser cladding samples

Laser hardening

Laser hardening is a surface hardening process, it suits best to steels and cast iron with a carbon content of more than 0.2%. Laser transformation hardening is a relatively straightforward process and involves rapid heating of the steel surface to the austenite region, which is then followed by self-quenching to form a martensitic case of high hardness. Laser hardening allows hardening of local well-defined areas, high-intensity local heating and very high self-cooling rates.

Laser hardening is most effective when either relatively small areas of a large component need to be hardened or features of the workpiece are too fine for traditional hardening methods.

4kw LPSS laser can be used for surface hardening
6kw HPDL suits very well for surface hardening

For more information, please contact: Jyrki Latokartano

Hardening of inner surfaces

20mm laser hardening tracks

Laser welding of metals

Laser welding is separated usually to two different processes, namely heat conduction welding and deep penetration welding. Both welding methods generate a nice narrow seam.

Heat condution welding is a process that can be used to joint thin -wall parts, usually thicknesses of 1mm and less. Penetration depth is small and the weld width is always greater than weld depth. Heat conduction welding seam has very high visual quality and requires usually no finishing. Process can be done with a pulsed and CW lasers and does not usually require high brigthness.

Deep penetration welding requires high density continuous laser beam, which forms a keyhole to enable deep penetration into material. Deep penetration laser welds are usually very narrow and deep. Well controlled and effective energy coupling into material enables good seam quality and high processing speed.

TTE lasers for deep penetration welding: 4kw LPSS laser
Possible lasers for heat conduction welding: 6kw HPDL, 300w HPDL, 150w pulsed LPSS

For more information, please contact: Jyrki Latokartano

Laser welding with Nd-YAG laser

Laser brazing

In brazing, two metal edges are joined by melting a different metal placed between them, typically introduced as a wire. Mostly used filler materials for brazing are copper based alloys (CuSi3). Brazing is one of the fastest growing applications for diode lasers.

Axially symmetric diode laser used for this process

For more information, please contact: Henri Pajukoski

Laser brazing sample

More examples of laser processes and equipment at Production Engineering YouTube channel

Laser equipment

Corelase X-LASE is a picosecond pulsed fiberlaser for microprocessing. High repetition rate of the laser allows high beam movement speeds. The laser suits well for accurate removing of thin layers as well as silicon-glass and glass-glass joining. The laser is typically connected to the LD-10 workstation. Back to Top

Specifications:	Wavelength: 1064 nm (24 W) Repetition rate: 1-4 MHz Pulse length: 10-30 ps Pulse energy: 6 µJ max Beam quality: <1,5 M²
Focusing optics:	Beam diameter: 2 - 30 µm depending on the optics

Eolite Boreas is a nanosecond pulsed fiberlaser which can be used for micromachining. Basic wavelength of the laser is 1030 nm and it can be modulated to 515nm and 343nm. Basic wavelength (1030nm) allows the highest pulse energies and is hence suitable for efficient machining. Wavelength of 515nm is very suitable for machining of copper and brass. The shortest wavelength (343nm) suits well for example for polymer machining. Back to Top

Specifications:	Wavelength: 1030 nm (30 W), 515 nm (15 W), 343 nm (7 W) 10-200 kHz, 7-15 ns 350 µJ (1030 nm, 10 kHz) 180 µJ (515 nm, 10 kHz) 80 µJ (343 nm, 10 kHz) Beam quality: <1,5 M²
Focusing optics:	Scanner Beam diameter 10 – 70 µm depending on the optics and the wavelength

SPI 20W module SPI 20W Compact Fiber Laser module is a continuous wave (CW) fiber laser. The laser power can be modulated up to 50 kHz. It can be used e.g. for marking, polymer welding and sintering.
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Specifications:	Wavelength: 1090 nm) Power: 20 W Beam quality: <1,1 M²
Focusing optics:	Scanner Beam diameter 20 – 70 µm depending on the optics Camera in the optical axis

Cavitar CaviPro 500W is an axially-symmetric direct diode laser. Diodes are placed at the periphery leaving an opening of 20mm through the laser. This space can be used for material delivery, analysis ect. This enables easy axial feeding of powder and wire in cladding and brazing processes. Back to Top

Specifications:	Wavelength: 940 nm Power: 500 W
Focusing optics:	Beam diameter: 500 – 800 µm depending on the optics

Laserline LDM-400 Laserline LDM 400/300 is a 19" rack mountable diode laser module. The laser beam is delivered to the focusing optics with optical fiber. Applications for the laser are among others polymer welding, sintering, brazing and small scale cladding. Back to Top

Specifications:	Wavelength: 940 nm Power: 300 W Beam quality: 40 mmmrad Fiber beam delivery (400µm)
Focusing optics:	Optics f100 ja f200 Pyrometer On axis camera Scanner

Liekki OE-500 Liekki (now nLight) OE500 is so called optical machine. Laserline LDM pumps energy to the fiber laser. The laser is suitable for thin foil cutting and welding. Marking applications are also possible. Back to Top

Specifications:	Wavelength: 1070 nm Power: 100 W Beam quality <1,3 M² Fiber beam delivery (20µm)
Focusing optics:	Optics f50 and f100 Scanner

Lasag KLS246-502 is a lamp pumped pulsed Nd-YAG laser. It is well suited to precision machining. With cutting optics it is possible to cut sheets from thin foils up to 3 mm thick sheets. The laser is also suitable for drilling. The energy flow to a workpiece is well controlled and hence the temperature of the workpiece can be held at low level. Back to Top

Specifications:	Wavelength: 1064 nm Power: 250 W (ave. power), 6 kW (max pulse power) Repetition rate: 0.1-1000 Hz Pulse length: 0.1-20 ms Pulse energy: max 50 J Adjustable beam specifications Pilotlaser
Focusing optics:	Beam diameter 0.050 - 1 mm depending on the optics and mirrors Camera on optical axis

HL 4006D Trumpf HL4006D is a CW lamp pumped Nd:YAG-laser. It is suited for many kind of traditional laser processes such as cutting, welding, hardening and cladding. The beam is delivered by optical fiber which improves the flexibility of the laser. Back to Top

Specifications:	Wavelength: 1064 nm Power: 4 kW Beam quality: 25 mmmrad Pilotlaser
Focusing optics:	Welding axis (camera on optical axis) Cutting optics Bi-focal Lineoptics Integrating mirrors(10x10mm, 10x20mm) Coating nozzle

Rofin DL060H2 is a CW direct diode laser. The laser is well suited for cladding and hardening of large areas. Pyrometer enables accurate control of hardening temperature and it reacts quickly to changes in workpiece surface profile. Specially designed cladding nozzle enables cladding productivity up to 6 kg/h. Back to Top

Specifications:	Wavelength: 810 nm (3 kW), 940 nm (3 kW) Continous wave (CW) Laserhead: 380 x 220 x 220 mm, 15 kg Pyrometer
Focusing optics:	Beam size 1,5 x 5 mm, focal length 113 mm Beam size 3 x 10 mm, focal length 250 mm Beam size 6 x 15 mm, focal length 350 mm Beam size 8 x 20 mm, focal length 430 mm Cladding nozzle (IWS)