UV laser

Important links:

Laser calibration

Laser parameters

Laser calendar

ABSOLUTELY NO USAGE OF THE LASER WITHOUT INTRODUCTION!

Check the list “History of Repairs and Service” at the end of this page for current issues with the machine.
+++ New vacuum chucks installed, please read this before you use them! +++

Our group has access to a UV marking laser, that is owned by the FRIAS institute. It can be used to machine most MEMS materials up to a thickness of 1mm. The quality of the cut depends on the choice of material. Silicon and PDMS can both be cut with an accuracy in the 30 micron scale, depending on the thickness of the cut. The basic machine properties can be found here (in german): Laser properties. The system is equipped with an alignment system so that wafer substrates can be accurately processed.
An overview of what is possible with the laser and a good overview of the setup can be found in the Bachelor thesis of Uwe Gleißner (german) (Year 2009, archived on our server).

Test structures cut with the UV Laser: Silicon pillars (left) and lines in Kapton foil (right) [Bachelor thesis Uwe Gleißner 2009]

The quality of the cutting results depend strongly on the used laser parameters. A collection of parameters can be found here: Laser parameters. If you find parameters that work better or use a different material, please add them to the list.

How to use the machine

The laser system is operated in the MA lab on the 2nd floor. If you want to use the machine, you need the approval of both Prof. Korvink and Prof. Wallrabe. After that you can get the introduction to the machine by the responsible person. It is split into two parts, the basic introduction and the introduction into alignment and stitching. Each introduction takes about 1.5h. The introduction notes can be downloaded here:

Laser intructions	Alignment instructions	Stitching instructions

You can also download the TRUMPF software manual here.

Important Rules

Every time you use the machine, make an entry in the machine logbook

If you get an error message or experience unusual system behavior (e.g. low laser power), make a note in the logbook and inform the person responsible for the laser.

Every time you move the Z-stage, you hand must be on the emergency stop button. There is the possibility that the laser head crashes into the XY-stage and we don't even want to imagine what the result will be.

Don't leave the laser running if you don't use it. Even if the machine is not lasing, the pumping diodes are on and these have a limited lifetime! So no overnight lasing unless it is absolutely necessary.

Book your lasertime online over the googlemail calendar. You get the username and password when you get the introduction.

Known issues

The laser needs at least 30-40 minutes to warm up. After about 10-20 minutes it is possible to start lasing, however the machine doesn't have it's full power yet. In order to get to a defined state, you will need to cut for at least 10 minutes into a dummy substrate, just leaving the machine switched on won't do the trick!

The laser loses power over time. This can be checked by a reference cut into silicon: The following parameters should cut through a piece of 300 µm Si wafer:

100% Power	v = 10 mm/s	f = 20 kHz	5 lines, 125 µm wide, 16 repetitions

If laser power is low, the person responsible for the laser has to call the TRUMPF support. They will increase the current through the pumping diodes. If the pumping diodes fail, they have to be replaced (~€ 10.000). The maximum power that can be applied to the diodes is 26W each. Above that, other parts of the laser might be damaged. In this case, the TRUMPF support can still increase the power by optimizing the temperature of the diodes.

Important facts

Machine serial number: E0952A0010

TRUMPF support: 07422 515-570

Telephone number of the laser for dial up service: 0761-203-7146

Laser head number: 0N690-1094-01

As of 17.12.2012: 8150 operating hours

Wires for the DXF-step communication. Click to enlarge.
Light bulb for the laser illumination: 12V/20W 36° GU5.3 (ordered from www.spezilamp.de, order#101449)
Light bulb for the microscope illumination: 21V/150W GX5,3 (ordered from www.spezilamp.de, order#101043)
Security light bulb (orange light on top of the workstation, laser won't work if both lamps are broken): BA15D 5W 24V (ordered from www.conrad.de, order#585106 - 62)

How to measure the linewidth and accuracy of the laser

A laser cut can be measured most accurately with the Leica DM4000 Microscope. A tutorial on how to perform measurements with it can be found here.

How to calibrate the axes

Calibration page

Pics of the wiring inside the laser head

Exchange of the diode current driver module

Technical drawing of the vacuum chucks

Download SolidWorks files

History of repairs/Service

Note: This list is not complete! There were far more problems that required the assistance of the TRUMPF laser service. Here, just the most important ones are listed

Date	Type of error	Repair	Comments
01/2009	Laser not working	Laser head replaced (warranty)	–
2009	Safety lamps broken - machine down	Replace safety lamps (top of the machine	We ordered spare lamps, can be found in the laser drawer
12/2009	Multiple error messages	New firmware uploaded	–
2010	High humidity inside the laser - machine down	Replace drying agent	New drying agent ordered
2009	Pump for water cooling broken	Replace cooling unit	–
07.12.2010	Connector for water cooling broken	Replaced with metal connectors	Pictures of the repair process
2011	Laser Diode Controller broken - machine down	Replace Controller Board	–
07/2011	High humidity inside the laser - machine down	Replace drying agent	New drying agent needs to be ordered!
29.11.2011	Low laser power	Increase Current through pumping diodes	20.5W/19.5W (Diode 1 & 2) 30.11.2011: Laser power still low, benchmark failed. Update 14:00 benchmark successful, cuts in glass substrates still not working.
06.12.2011	Low laser power	Increase current through pumping diodes, temperatures adjusted	cut through glass still not successful
23.01.2012	Bulbs for the microscope and the laser illumination broken	Replace bulbs and order new ones	–
15.03.2012	Scanner head broken, new scan head ordered (4700€)	new scan head installed, accuracy not tested yet	Error and Warning log (15.03.2012)
April 2012	New scanner head doesn't have enough accuracy	Calibration by Trumpf Service (~1000€)	Accuracy of around 25µm
May 2012	Laser out of focus!	Adjust a defocus in the parameters, no response from Trumpf yet.	The current defocus can be found on the Laser calibration page
08.06.2012	Laser out of focus	Optic offset adjusted to 116 –> No defocus	Trumpf service will continue to investigate the problem
12.06.2012	Error: Cooling water flow is too low	Cooling water @ 77%, filled to 100%; cleaned particulate filter.	New filter needs to be ordered
02.07.2012	Scanner axes not orthogornal	We will need a new calibration	Angle of around 0.2° between X and Y. Letter to TRUMPF
30.07.2012	Security lamp broken	Replaced	New lamps need to be ordered, placed order in conrad list
Since Dec. 2011	Multiple issues with the new XY stages	Not resolved yet	Erfahrungen mit PI miCos - Update
08.08.2012	–	New vacuum chucks installed
09.08.2012	Scanner axes not orthogonal	TRUMPF service re-calibrated the scanner	New calibration was free of charge for us “Kulanz”
17.12.2012	Loss of laser power	Pumping diode current increased to 30.2 A	Laser power now rated at 2.0 W
17.12.2012	Laser out of focus	Optic offset adjusted to 131
26.06.2013	Waterflow problems	Particle filter cleand, Fresh cooling water
13.11.2013	High humidity inside the laser - machine down	Replace drying agent	We ordered 2 drying agents, they can be found in the laser drawer
13.11.2013	–	DI Filter	We ordered one filter, it can be found in the laser drawer
27.04.2015	Laser base plate	Exchanged with new
09.06.2015	General maintenance	Particle filter cleand, Fresh cooling water, new Ionfilter, new filter mat, replace drying agent, grease in the z-axis rail	We have one Ionenfilter and one drying agent left
15.10.-27.10.2015	Laser not working CAN Connection error	Exchanged with new CAN BUS Card	If error is showing up again change OMI PCP and /or CHL PCB
11.01.2016	Laser not working CAN Connection error	Exchanged with new IVC PCB and PC system
12.01.2016	Laser not working CAN Connection error	Exchanged with old IVC PCB	New IVC is brocken
18.01.2016	Laser not working CAN Connection error	Exchanged with new OMI PCB	Service from Trumpf Herr Fehrenbach
02.03.2016	Changed RAM	2 GB to 3GB
08.06.2016	Laser not working Pumpmodule error	Desiccant in pumpmodule	Next time change pumpmodule
21.07.2016	Laser not working Pumpmodule error	Exchanged the pumpmodule	Power is rising and breacking down afer a while
23. - 24.08.2016	Laser not working Error to the supply unit	Exchanged the CLH PCB
09.09.2016	Change of laser head by Trumpf	Exchanged the laser head	Pump module send back, CLH and old laser head back to Trumpf
27.10.2016	Exchange of PMMA and repair of special features	-
07.03.2017	Laser Markingfield calibrated	Calibration by Trumpf Service	Accuracy of around 25µm

It is possible to check the laser power, however this must only be done by the person responsible for the laser! When in doubt: Contact the TRUMPF support. Kontrolle der Laserleistung mit Diagnosetool 2.2 Laser power control with diagnostic tool v2.15