This is an old revision of the document!

Table of Contents

  1. Overview
  2. Q & A
    1. Using a “new” material
  3. Common processing errors
    1. The pre-toolpath file did not import correctly.
    2. The fiducials did not move/moved incorrectly when I moved the design during “Placement”.
    3. The bottom/top didn’t etch completely.
    4. The board is/is not flipped in the Processing tab.
    5. The software throws and “Insufficient pressure” error.


The LPKF ProtoLaser U4 is an automated laser etching and micro-machining tool. It uses a pulsed 5.7W 355 nm class 1 laser to reduce thermal effects on the substrate, and a laser spot size of 20 um allows for etching of structures down to a theoretical limit of 65 um (~2.55 mil). This combination allows for a very wide range of processing substrates and films, but it is particularly good for thinner substrates that the more physically-taxing ProtoMat may damage, organic/flexible substrates, and for very precise RF etching.

An incomplete list of compatible substrates and films:

  • Metal layers of all sorts, including copper, gold, and aluminum
  • Laminated substrates, e.g. FR4
  • Ceramics, including fired, low-temperature cofired (LTCC), metal oxides, and more
  • Flexible substrates, including semi- and selectively-flexible substrates
  • Soldermask
  • Photoresist
  • Glass/oxide, especially with invisible conductive (TCO/ITO) layers
  • Any material combination for which the absorption characteristics of the substrate and structuring layer (film) are different

Some theoretical specifications:

Spec Theoretical value
Laser pulse frequency 25 kHz–300 kHz
Structuring speed 200 mm/s (7.8”/s) on 18 µm/½ oz Cu on FR4
Cutting speed 200 mm/s (7.8”/s) 0.5 mm (0.02”) FR4
Diameter of focused laser beam 20 ± 2 µm
Minimum line/space 50 μm/20 μm (2 mil/0.8 mil), on laminated subtrate (18 µm Cu)
Accuracy ±1.98 µm (± 0.08 mil)
Positioning accuracy ± 20 μm
Repeatability ± 2 μm
Resolution 1.2 um

For more information, see the following documents:
The brochure: The Swiss Army Knife for the Lab: Micro Material Processing with the LPKF ProtoLaser U4
The Manual: ProtoLaser U4 User Manual.pdf
LPKF's “How-To” guides: ProtoLaser U4 How To Guides.pdf
Software guide: CircuitPro 3.0 PL - Software Guide.pdf
Vacuum system manual: Dust Extraction Manual CSA 600 iSeries-e-1-0.pdf
Optimizing your process: Protolaser - Optimization.pdf

Q & A

Using a “new” material
So you have a material that either isn't in the laser's material list, or maybe you just want to play around with the settings. Exciting! Head over to our ProtoLaser: New Material document for how to do this.

Common processing errors

  • The pre-toolpath file did not import correctly.

It’s likely that you either did not save at the correct point in the process, you saved over the pre-toolpath file, or you are trying to import the wrong file. Double check all of this. If you’re certain you did it correctly, get a PI.

  • The fiducials did not move/moved incorrectly when I moved the design during “Placement”.

Sometimes, when placing the board, the fiducials move in the opposite direction as the board. This is a known bug! You can either: try estimating the location of the fiducials and starting the process; start a new document; restart the software; or restart the hardware. (The latter two require a fresh 20 minute warmup for optimal performance.)

  • The bottom/top didn’t etch completely.

You can either restart the process entirely (hit the Play button, see figure 32) or right click on “Top Side” (or “Bottom side”) under “Processing” on the left, and click “Process from here” to restart the top (or bottom) side processing with top (or bottom) side alignment.

  • The board is/is not flipped in the Processing tab.

On the left of the screen, make sure nothing is selected under “Processing”. If there is, hold down either CTRL (on Windows) or the command key (on Mac) and then left click to de-select it. If that doesn’t fix it, you can select either “Bottom Side” or “Top Side” (again, on the left) to force the correct orientation. You can try starting the project over again if this doesn’t solve it as well. Sometimes, the software has bugs.

  • The software throws and “Insufficient pressure” error.
    • Potential issue: The vacuum hose may be disconnected from the extraction hood.
      • Lift the door. The extraction hood is the plastic bit that the laser comes out of. There is a hose that should run from that to the back of the machine (still all inside the main bay). Make sure that its snugly inserted on both ends.
    • Potential issue: The vacuum system may not be on or working strongly enough.
      • Confirm that the vacuum system is on.The vacuum system is the tall white box to the tool’s right. On the front panel, at the bottom, there should be some buttons. Try increasing the suction pressure.
    • Potential issue: The vacuum hose(s) may be clogged.
      • There are two vacuum hoses. One runs from the extraction hood (the round plastic bit inside the main bay) to the rear interior wall of the tool, and the second runs from the outside backside of the tool to the vacuum system (the tall white box to the tool’s right). You should be able to remove both of these and check for clogs.
  • pcb-help_pl.1610918521.txt.gz
  • Last modified: 2021/01/17 16:22
  • by benh