Sunday, January 10, 2016

Cold Toner Transfer Circuit Baords

For years I have been using the toner transfer method for making circuit boards.  I have an old Brother printer and a Scotch TL902 laminator that have worked well for this.  One of the problems I have found with this method is that the type of toner you use is very important.  If I use real Brother toner, I get very good results for most of my boards. I have tried using generic toner cartridges that are about 1/3 the price, but have not been able to get very good results.  Another problem is with large ground plane areas, I have  had problems with etch through, and pin-holes showing up in these areas.

I recently saw a post on Instructables about using a chemical method instead of heat to transfer the toner to the circuit board material.
http://www.instructables.com/id/Heatless-cold-Toner-Transfer-for-PCB-Making/?ALLSTEPS


Since my Brother toner cartridge was just about out and I would have to order a new one fairly soon, I decided to give it a try.
Looking around all my painting supplies, for solvents I found a can of denatured alcohol. The original article used Acetone , which I did not have, but I had  some Xylene I had used for thinning and cleaning up some enamel I had painted.  

I printed up several copies of a board I need to etch using the generic toner cartridge.  Playing around with different mixtures of denatured alcohol and Xylene.  I found that a 5 to one 1 mix of alcohol to Xylene would soften the toner without causing it to smear instantly.  I tried the method as shown in the video with fairly good success, and then tried to modify the method a little.  Here is what I came up with.

With an eye-dropper I put enough of the mixture on a cleaned board to evenly cover the board.  Then place the printed paper on the board and moved it around to position it properly on the board. 
After it was positioned on the board, I used the eye-dropper to saturate the paper with more of the mixture.  You could see the paper becoming more transparent and clearly see the toner pattern.
I let this set for about 30 seconds, and then covered with a folded over paper towel.  I then placed another piece of circuit board material on top of the paper towel and applied pressure for about 2 minutes.  After that time I removed the top board, and used the rounded back of a fork to burnish, through the paper towel.  After  it looked like much of the mixture had dried, I removed the paper towel and burnished the laser paper directly.  You could clearly see the toner pattern through the paper.  After a couple of minutes of that, I left everything set for a couple of minutes for the last of the mixture to dry.
After it was dry, I soaked the board in water for a couple of minutes, and removed the paper by lightly rubbing with my fingers.
The toner on the board looked nice and crisp, good adhesion all over, and no sign of smearing.  After etching the board, I found very nice traces, no problems where traces went between IC pins.
Also found nice smooth ground plane areas, with no etch through, or pin-holes.
Looks like I will be able to save a lot of money on toner, and finally retire the laminator.  Probably only used about a half a teaspoon of the mixture, so the remainder of the quart  cans of alcohol and Xylene I had around should last a very long time.

 
Just a couple of pictures of the boards done with this method.
 
The completed board, and a close up showing the sharpness of the etching , and nice solid ground plane area without pin-holes.


Now to get to doing something with these boards.


 

 

8 comments:

  1. What kind of paper do you use?

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  2. Replies
    1. Thanks for that; we've been having a lot of trouble in that Instructables thread trying to identify what specific kind to use. I've never done my own board before, and I'm excited to try your method very soon!

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  3. Great idea. Thanks for sharing. !

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  4. Great idea. Thanks for sharing. !

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  5. Did you stay with the mixture of 5 parts alcohol & 1 part xylene?

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    Replies
    1. It's about 5 to 1. Print up a test pattern with some lines of different widths. Take a Q-tip with the mixture and run across the lines if it smears add a little bit of alcohol. You want it to soften the toner not smear instantly.

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  6. I plaid with this method whole today and have the same problem. Toners does not stick strong to the board. Of course, i can put it into the over for several minutes, but that means i have to heat up the oven and waste time and electricity. This is not way. If it is need then i will stick to photoresist.
    So, i and xerox 5010 led printer with nobrand generic toner. The toner transfer very will to pcb, but when i try to clean up the paper picks up from the pcb. I tried to use NaOH to dissolove the paper but somehow the whole layer just float from pcb. Crazy.
    PCB is prepared by gritting with 1000 grit sand paper and cleaning with 10% ammonia. Tried just spirit, all the same.

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