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So you made a few boards. Or not! Either way, this is a running list of tips and tricks for users - things to do and things to avoid. We make no guarantee with any of these, but we have found that they've helped us in some way.

  • Plating is typically avoidable by making vias with a diameter of 40 mil (1 mm). A standard 0.1” header pin can then be pushed through and soldered on both the top and bottom.
  • Higher polygon isolation will reduce the chance of bridging to a plane during assembly (since we don’t really offer soldermask). However, it will also increase etch time because more of the substrate will be etched. “Isolataion” is usually a setting that you can edit per specific polygon; 10 mil is the default often, but 24 or 32 mil (or more, though the benefits decrease) will reduce the risks further.
  • Slots! We can do them! There are probably a couple of methods for doing this, but the way we've had success is to add the slots onto the “BoardOutline” layer in the software. How this happens depends on your EDA (CAD) software, but in essence, you either need to have your slot in a new gerber (which you can assign to “BoardOutline” in the Import step) or you need to put your slots onto the layer in your EDA that spits out your Board Outline gerber file (in Eagle, this layer is called “Dimensions”). Unfortunately, we haven't found a good way to do plated slots because in the above method, the slot is made after the etching is done (and therefore after the plating would be done). An alternative in this case would be to design your slot as overlapping drill hits which are done prior to plating.
  • If you're interested in optimizing your ProtoLaser experience, see the LPKF ProtoLaser Optimization document for more information.
  • Laser precision is dictated by many things, some (even many) of which are likely beyond your control as a user. Here is a completely-uncomplete list of some of these things (a * indicates things that you, as a user, will not be able to adjust, but get in touch if you think it's a major contributor to any issues you're seeing):
    • Flatness of your substrate
    • Laser power and other material-specific settings
    • Design choices (e.g. spacing, trace widths, substrate, copper thickness, etc.)
    • Position of the design on the substrate (left, right, center, etc.)
    • Cleanliness of the laser lens*
    • Level-ness of the floor*
    • Level-ness of the sample plate*
    • Filter cleanliness*
  • One way to minimize systematic errors from the laser system itself is to do what might be termed a “dose test”. This would involve make a very small design that has one or more features at and/or around your actual design's minimum feature size. Think something that can be etched in a minute or two. You develop your material settings on this design so that you can try many iterations of material settings within a shorter time frame (and you can likely fit many of them on a single sheet of your substrate) while keeping in mind that there are some things out of your control. Once you've determined settings that seem to work, do a test etch of the dose-test design prior to etching your actual design. If done properly, this can tell you if the etch will be up to spec for your work. Try to hold as many systemic parameters constant as possible, e.g. the same position on the substrate, the same substrate piece, etc.
  • Another suggestion for the laser would be to define a metric for etch quality using the aforementioned test design. That way, you can quantitatively determine which parameters are doing better than others.

The Book of Kane

  • pcb-tips.1644879271.txt.gz
  • Last modified: 2022/02/14 17:54
  • by benh