March 9, 2006 AT 2:08 am

Home etching

I miss the awesome PCB etching setup I had back in the media lab so I decided to put together one here at home.

So far so good, it took 3 tries to get anything decent out of the toner transfer system. I highly suggest the “dowel roll” method for high pressure. All in all, I dont like toner transfer. Photoresist is way superior. However, if you have a laminator apparently everything works a lot better so I’ll be looking into that.

I have some more photos on flickr and a more detailed tutorial later. The etching system is the hardcore MG 7liter. One thing I can say for certain: its more than 7 liters and, secondly, its very hardcore. The regulated heater, thermometer and sparger are awesome and saved me the effort of building a similar system. I etched my 3″x5″ single sided 1oz copper board in about 5 minutes. With a high quality image transfer system (like a simple photoresist) one could definately go down to 10/10mil rule.

I think its way too big though, who the hell etches 8″x12″ boards? I can rarely get consistant exposure over 6″x8″. I may get a different sized tank and keep the nice heater and sparger/manifold/thermometer.

Drilling is performed with a Dremel “multi pro” 3-15krpm in the Dremel “workstation/press” fitted with carbide wire-size drills.

Anyways, thumbs up for the MG “pro etch system” and a no-so-thumbs up for the Pulsar toner transfer system.


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6 Comments

  1. I used to do toner transfer the really hard way. I bought glossy photo paper, and transferred the pcb drawing by pressing it to the paper between two aluminum blocks and sticking it in the oven for half an hour.

    I recently bought the Pulsar starter kit, and it’s a really great system for $100. The laminator transfers the image well. Also, with their TRF you can just rub the board in room temperature ferric chloride. It only takes a couple minutes, and all you need is a sponge.

    Overall, I’ve been impressed. I recently did a few boards with the TQFP Atmega168, and the board came out perfect every time. My only problem with it is that they have you use thinner boards to fit through their laminator. These thinner boards can be much easier to drill, but of course they can bend, leading to broken traces.

  2. Ya the 31mil board requirement was something i noticed too. I rather like 62mil which is why I’m a little hesitant. One thing: perhaps its easy to open up the laminator and widen the gap?

  3. The 31mil boards, in addition to being much easier to drill, can also be cut with a paper shear, which means making panels of boards can be a lot easier. I don’t think I’d recommend it at all for boards bigger than about 5×5 inches, though.

    Pulsar used to recommend modifying a laminator to accept 62mil boards. I don’t think it would be too difficult, but I’ve never done it.

    Of course, I’ve never done photoresist, so I can’t compare. Doing a 3×5 board takes me about 20-25 minutes, going from a finished design to an etched pcb (not counting waiting for the laminator to warm up, which takes a couple hours). I’d estimate it costs around $2-$4 (for etchant, trf, board). And I had to buy a $60 laminator to do this.

    Could you give a quick overview of the costs (time and money) of photoresist etching?

  4. It dawned on me that making a simple photoresist setup would be very simple, you could print out the circuit using a laser printer onto transparency paper, but you would print a negative instead of a positive, then with this negative, you would just place it ontop of your photosensitive pcb, put it under some Blacklights (UV Light), then etch it as you normally would, this is essentially what we do at my college, except instead of printing using a laser printer, they have a camera and we take pictures onto film, then put that negative onto the pcb and then put it under a blacklight. Someone should test it out!

  5. I make PCBs the cheap way. Print with a laser printer on a glossy paper, then transfer it with an iron. It works pretty well for me.

  6. I’ve used the toner transfer method for years. Works well for me. Eagle PCB design workers great for schematic capture and then board design. I save the image at 300 DIP black and white and then print it onto PCB Press-N-Peel Blue emulsion film. I bought a press that they use for T-shirts and transfer the toner using this good press at high temperature for set time. Then I etch it in the bathtub in a clear plastic container. That’s the time consuming part. Drilling as you mentioned, only don’t use steel wool after drilling because all the holes will fill with little metal filings.

    I’ve gotten better at doing boards but then got to busy. So now I use PCBFABEXPRESS.com to design my boards. See the boards I’ve designed for customers at http://www.funwithmicros.com

    Brad :)

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