Friday, January 29, 2016

Double sided cold toner transfer experiment

I was very happy with the boards I made using the cold toner transfer method, and wanted to see how it would work for dong two sided boards. 

 I had a small board I waned to make that has a full ground plane on one side.  I printed the toner patterns directly in Eagle, making sure to mirror the top side.  The best paper I have found for this is Color Laser Gloss from Hammermill.  It is much thinner than photo paper but has the same glossy surface, and is only about $15.00 for 300 sheets.  

I cut the patterns in  long strips, and trimmed the top pattern so it had about a 1" overhang from the  each side of the toner pattern.  Then using a strong back-light I aligned the two patterns and taped the top pattern to the bottom.  I then stuck a piece of paper in between the two patterns to
protect the bottom pattern while I worked on the top.

Using an eye-dropper I placed a small amount of the solvent on one side of the prepared board blank., and slid it between the patterns. After positioning the blank I applied a few more drops of the solvent on top of the paper and spread it around until I could clearly see the toner pattern through the paper.


When It was positioned where I wanted it I placed a piece of printer paper on top and covered with a piece of blank circuit board.  I applied pressure for about a minute to set the toner in position.  I then removed the blank board and first with the paper still in place I used the back of a fork to burnish the toner pattern.  After a little while the paper began to become more opaque.  Then I removed the piece of printer paper and continued the burnishing with medium pressure.  

 When it looked like all the solvent had evaporated from the paper, I turned it over , removed the piece of paper that had been there to protect the bottom toner pattern.  Carefully lifting the pattern slightly I put a few drops of solvent on the board blank and spread it around until even.  I added a little more solvent to the top of the paper until I could clearly see the pattern.  I processed this side the same way as I had the other.

 I checked the board and everything looked fine.  I found one or two small pinholes in the toner on the large ground plane area that I touched up with a marker.  After etching I drilled a couple of holes in the board to check registration.  The photo shows the same hole as seen from both sides of the board.  The registration was much better than I had ever been able to get using the hot method with a laminator.


  1. Hi DuWayne

    what did you use as solvent?
    And what did you use for etching?

    Iam new and think this method look far better than other, so iam missing the Chemical Things ;-)


  2. Almost any solvent should work. I did not have any Acetone, but did have some Xylene left over from some painting I was doing. You want to modify the ratio of solvent to denatured alcohol by printing a test page of various width lines, then with a Q-tip dipped in the solution run it across the lines. You want to keep increasing the amount of alcohol until the lines no longer smear. You want the solvent mixture to just soften the toner.
    You use very little of this solution per board. I ended with 1 OZ of Xylene and about 5 Oz of denatured alcohol, And after about 15 boards I still have 20% of the solution left in the bottle.
    I have modified the procedure slightly. Instead of pressure and burnishing the board, I now pass them through my laminator a couple times in different directions. This seems to get more even pressure on all parts of the board, especially larger boards. For this I do not have the laminator warm up first.
    For etching I use a Muriatic Acid, Hydrogen Peroxide mixture. A lot less messy to work with, and only have to mix up about 2 Oz of acid to 4 Oz of Peroxide at a time. Nice thing about this method, is that I just used what I had on hand form other projects. Only thing I bought for this was the Glossy Color Laser paper, and I also use that for other things.