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Thread: Using laser to expose etching surface

  1. #1
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    Default Using laser to expose etching surface

    Hi,
    I am running a 445nm M140 laser diode and have been trying to use it for removing masking material from metal surfaces to be etched. For instance for PCB etching etc.

    I tested a number of paints applied to the metal surface, but have not been able to completely remove them with the laser, even after multiple laser passes.

    I have also tested applying various tapes and etching into them, but there is always an adhesive residue left behind.

    Has anyone had experience with doing this and can recommend a masking material or process?

    thanks.

  2. #2
    swamidog's Avatar
    swamidog is online now Jr. Woodchuckington Janitor III, Esq.
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    you'll have much better luck moving to a higher powered laser. low power co2 systems are fairly cheap these days and would do the trick very nicely.

    Quote Originally Posted by Anachronicman View Post
    Hi,
    I am running a 445nm M140 laser diode and have been trying to use it for removing masking material from metal surfaces to be etched. For instance for PCB etching etc.

    I tested a number of paints applied to the metal surface, but have not been able to completely remove them with the laser, even after multiple laser passes.

    I have also tested applying various tapes and etching into them, but there is always an adhesive residue left behind.

    Has anyone had experience with doing this and can recommend a masking material or process?

    thanks.
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

  3. #3
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    Hi Swamidog,
    Thanks for the suggestion and info. At the moment I am developing my laser diode based system and changing to co2 is not an option for me.

  4. #4
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    Anachronicman,
    I have made some PC boards with my 445 LD, and I used Krylon flat black spray paint. Have to do two or three slow passes, followed by scrubbing with BonAmi pot cleaning powder and a toothbrush.


    John Champlain
    www.picengrave.com

  5. #5
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    ... I'm doing this with different black spray paints - I'm only looking for 'ultra-fast drying' ones ... or high-temp oven-spraypaint.

    After engraving there are some carbon black residues in the burned line, what's best removed with alcohole -- it doesn't solve the paint, if done fast and carefully ...

    Viktor

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    Why not just use a normal UV cure boards with a 405nm laser. Put the board in, turn on whatever you use to scan the image, turn it off and etch or wash then etch. Been so long since I did that I forget. By the time you do all this you can buy a finished board from a a board house with drilling and vias plated and all done for you with a pro looking mask. Even double sided is not that expensive. Get the barebones board. Sometimes it is better not to do it yourself.

    I tried doing what you are doing with a a co2 laser and it works well. There are limits to resolution for fine pitches parts.

    forgot, the old way. Draw it using a pen and etch.

  7. #7
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    ... spraying copper black, engraving and etching the outlines and last removing the paint is a job for around 30 minutes ... most of this time for drying the paint

    Here I've posted something about this sort of laser-engraving: http://forums.reprap.org/read.php?133,235148

    Viktor

  8. #8
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    Thanks for the great feedback.

    The residue being left behind is where I have been having most issues. I will try the ideas put forward.

    I have been testing with a spray-on vinyl coating which my laser removes very easily and cleanly (with proper ventilation of course!). I have also tried Plasti-Dip. Both of these products have the advantage of peeling off easily afterwards. I will report my results when I have had more time to experiment.

    I agree that it is easier to have PCB's manufactured externally these days far more easily and cheaply, with masks, drilled and with proper vias. The problem is the many-weeks wait for your board to arrive.

    My goal is to etch through a thin metal, such as brass or stainless steel to create something like this:
    Click image for larger version. 

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  9. #9
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    I clean the blank pcb well (bit o steel wool, and give it a good scrub). Cover it with a piece of craft vinyl film (https://www.amazon.com/dp/B0725XWZ3N). Then shoot on my design. Use an exacto knife to help lift out the not traces part... careful not to nic or move the traces of course. Burnish it a little bit when your done with an eraser or spatula kinda thingie.. And toss it right on in the etch. The rest of the vinyl peels off when yer done.

    Might also note that burning vinyl is very very bad, and should always be done with lots of active air scrubbing, or just take it outside. As well, the hydrogen chloride is not very good for your kit, lens, etc.

    Cheers
    Anjin

  10. #10
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    Dupont Riston® LDI8300 photoresist sheets.
    We use it at work for very fine stuff for microfluidic channels. Sorry, can't give you a sample. Mainly because we only use a tiny amount , enough to cover a 4" wafer, and order samples ourselves.

    If we're doing repetitive work we order 23,000 DPI masks for 80$ a for a 4x4" mask instead of lasing. For that we use a 365 nm Riston or one of the PCB oriented clones, at ~ 10$ a sheet for a 8.5x11.

    Riston does not get burned off. Makes life soooo much easier.

    I cant give you any other details till the student publishes her thesis, sorry.


    Steve
    Last edited by mixedgas; 08-03-2020 at 15:03.
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