UV laser

Important links:

• Laser calibration
• Laser parameters
• Laser calendar

Check the list “History of Repairs and Service” at the end of this page for current issues with the machine.

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.

The laser system is operated in the MA lab on the 2nd floor. If you want to use the machine, you need the approval 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:

• 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.

• The laser needs at least 60 minutes to warm up. After about 30 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 30 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:
  

• 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.

• 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 21.03.2012: 6843 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)

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.

Calibration page

Exchange of the diode current driver module

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

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