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Thursday, May 2, 2013

2-Layer Circuit Boards Using Laser Cutter / Chemical Etching

I've kind of been obsessed with trying to make circuit boards on my laser cutter since I got it. Other people had already done this by using spray paint as resist - then laser-etching the paint off non-trace portions of the board. This process still requires chemical etching - which I've been trying to avoid.

I had some success several months ago - making crude PCBs by laser cutting thin steel - but those boards aren't good enough for surface mount components or anything complicated.

So - if I can't make good boards without chemical etching - I figured maybe I could use chemicals in conjunction with the laser cutter to make some decent 2-layer boards.

After a few failures - I came up with the process documented in the video. It works pretty well! I suspect if streamlined a bit - you could go from Eagle to working board in under 90 minutes.

My first project is a demo board for the ATtiny43u - a nifty little microcontroller that uses a voltage booster to run on as little as 0.7 volts. The booster can even power small external devices requiring a higher voltage - like an LED.

Resources:
Eagle files for ATTiny43u Board
Etching with Copper Chloride in Aqueous Hydrochloric Acid Solution
Atmel ATtiny43u
Youritronics - Double layer pcb home made vias

9 comments:

  1. I like your idea of making a positioning jig first. I would have attempted to go straight for some screw holding device, create a board out of a much large piece of FR4 and then cut the excess off. But then I would be cutting a complete board - one wrong move with that saw and it's damaged :)

    Do you think the laser may be powerful enough to ablate the copper itself if you used, say, a scissor-cut thin copper clad (forgot the official name - a very thin board sheet). I'm curious about any technique that exists which could eliminate the need for etching.

    Thanks!

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    1. While I've been able to cut-through thin copper that's been painted black - I've never been able to do so cleanly / reliably enough to be useful.

      Bare copper is highly reflective to infrared - and even unpainted copper leaf (super super thin) acts as a mirror. If you're not careful - the reflected light will melt tubing / other laser cutter parts (voice of experience).

      FR4 itself is also very difficult (and probably toxic) to cut.

      Not discouraging anyone else from trying - I've just had trouble getting useful results.

      -Rich

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  2. How about an IR laser to expose the UV photoresist instead?

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    1. This comment has been removed by the author.

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  3. Nice project. I have the same laser and have tried this also, but without success. Which paint do you use?

    Lars

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    1. Using "Kryol Fusion" - didn't think it mattered. Since sounds like it might - added note to the video.

      -Rich

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  4. I freaking love it! I will be trying this. I hate trying to line up double sided boards so I try like heck to only make single sided boards but this might just be the ticket to doing double sided boards and give me that extra push to try some new stuff.

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  5. What FR4 material did you use? I love the black substrate.

    ReplyDelete
    Replies
    1. It's some stuff I got off ebay.

      Check the seller "abcfab" - I think he has some more.

      -Rich

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