Getting toner transfers straight and centered?

Discussion in 'General Electronics Chat' started by spinnaker, Dec 4, 2010.

  1. spinnaker

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    Oct 29, 2009
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    Anyone have any tips for getting toner transfers to copper straight and centered?

    I cut the paper nice and straight but I cut the paper a bit larger then my copper so it makes lining up an edge difficult.


    Also this assumes I am printing perfectly straight. Printing on magazine paper, this does not always happen. If I see it is really off then I reprint.


    I guess if I cut it perfectly centered I can find the two centers and line things up.

    But are there any other tips?
     
  2. nerdegutta

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    Dec 15, 2009
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    What if you make a frame around you graphic, a rectangle or square, do the transfer and the cut your board after the frame. If it's a little off before you cut, no one will ever see that if you cut it after the frame.

    Just thinking loud...:)
     
  3. gootee

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    Apr 24, 2007
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    Print the board edges on your circuit layout. On three sides (for rectangular boards), cut exactly on the board-edge lines. Problem solved.
     
  4. spinnaker

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    Yeah that might be the way to go but I read it is a bit easier for pealing the paper if you make it bigger than the board. But maybe if I just cut 3 sides to fit and leave the fourth longer.
     
  5. Wendy

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    Mar 24, 2008
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    My current project, note the corners on the print...

    [​IMG]

    I don't want to talk about the project at this time. When I have it tested (and it passes or fails) I'll bring it up in another thread.
     
  6. gootee

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    Um, Bill, shouldn't that inductor be labeled with uH instead of uF?
     
  7. Wendy

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    So what's your point? :D

    I tried feeding old PCB stock through my new laminator, it was too thick. I'm very sad, so I bought some new PCB stock after I destroyed the old stuff on a skillet (you don't want to know). I'm hoping I don't have to try to take that laminator apart to modify it for thicker PCB stock. It worked so well first time too.
     
  8. tyblu

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    Nov 29, 2010
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    Why are you worried about it being straight and centered? As long as all of your traces fit and are a cm or so away from edges, it will be fine. If it is to line it up one 2-sided board, drill a few holes through the paper and PCB first, then line up the holes.
     
  9. spinnaker

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    Appearances mainly.
     
  10. gootee

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    I was hoping it was a flux capacitor.

    A clothes iron works pretty well for all thicknesses.
     
  11. spinnaker

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    What laminator did you get? I was looking at this one. Says it can handle up to 6mm thickness. That is pretty darn thick.


    I tried the stove thing today myself. I have one of those flat top electric stoves. Even on warm I think it is too hot. I meted the paper right on to the copper. :) I might try again. This time don't leave it on so long.
     
  12. Wendy

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    Actually not. I was getting totally inconsistent results that completely went away when I used the laminator, and I'm not the only one having the problem if you read around. I've figured out part of the problem, the bottom is soaking the heat away as fast as the iron can input it. Irons come in many grades and wattages, mine is too cheap I guess. I'd rather spend the $30 for my laminator than a new iron.

    The only other thermal transfer that worked using the iron I held the iron on the transfer for 5 minutes, moving the iron the entire time (and pressing) to get an even heat distribution. This was after 9 or so previous tries, bumping the time of iron on transfer up each time.

    Since the subject has come up I was trying a large clean frying pan to inject heat from the bottom to prevent the problem, but don't put too much heat in or it gets ugly fast. I may also try a thick piece of smooth aluminum to spread the heat around, I strongly suspect an iron has hot spots, and it is hard to adjust for all of them.

    A laminator compensates for a multitude of sins. But if you use thick board stock it won't work.

    Use a large cast iron skillet or griddle, and adjust the temperature control. I don't know it will work, but it has a good chance. As I mentioned I would get a chunk of smooth (this is important!) aluminum or copper to spread the heat around from the iron.

    I don't think that laminator will work. It mentions 125°F, that seems way too cold. GBC makes good units, I lucked out and found mine for $30. Shop around, and look for something that is high heat. Mine has an adjustable temperature control. It is a GBC HeatSeal H210. It lists for much higher ($199), why mine was at such a low cost I don't know. It may have to do with them only having one on the shelf. The unit from Harbor Freight looks rather wimpy, and I suspect you won't get good results unless you do something like Project: Converting a hot roller laminator for toner transfer to modify it.

    Don't give up on the skillet method either, and look around for some thick sheet metal to even out the heat. You might look around for used laminators too.

    I have to be careful what PCB stock I use. Tanner's has started carrying it, I'll probably keep a log of thicknesses and how well it worked (or didn't, as the case may be).
     
    Last edited: Dec 5, 2010
  13. eblc1388

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    Nov 28, 2008
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    You have missed the negative connection of two capacitors to 0V as shown.

    [​IMG]
     
  14. retched

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    Dec 5, 2009
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    Two things I find helpful for lining up the toner print on the copper,

    1) Print an outline a mm or so larger than the board. Use a lightbox to line it up.
    The lightbox shines through the magazine paper enough that you can but the square over the board and line up the corners.

    2) A soldering gun/iron. I use the soldering gun to melt the toner in 3 or 4 points to tack it down. That is really helpful for 2 sided where you cant afford a slide when you are ironing or sending it through the laminator.
     
  15. shortbus

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    The secret with the iron is listed in original descriptions of the method, but it is almost always dismissed or not used. The secret is to put a wooden dowel rod under the PCB blank, you then roll the blank and iron back and forth. The dowel concentrates the pressure between the blank and the paper, similar to what the laminator does.
     
  16. retched

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    A nice thing about the laminator is constant, even pressure and temperature.

    And, no steam holes to help you miss a pa
     
  17. Wendy

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    Actually I couldn't put a trace between the power in and the capacitor, so I planned on using a wire to bridge this gap. It is one of the reasons I requested not to discuss the circuit on this thread, if it works I'll open a new discussion on it. C3 has two negative leads, I'm only using one of them. I'm trying several things out I know are weak to see if they work.

    The idea with the dowels is a good one, but the holes in the iron is why I don't use it. Maybe adding the sheet metal (let's call it a temperature distribution plate) might allow it to work. However, if the skillet works then it is simpler IMO.

    Thing to remember is the original OP's point. It is a good one, because it directly deals with two sided boards. Thinking about it I would etch one side at a time, masking the other side (toner maybe?). After you drill the holes they will provide line ups for the second side.

    You could do both sides at once, but without the holes it becomes more problematic. Maybe drill 4 fiducial holes in corners? Retched's post #14 seemed like a good idea.
     
    Last edited: Dec 5, 2010
  18. thatoneguy

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    Feb 19, 2009
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    I use registration marks to line up a double sided board.

    Another option is to leave about 1" of paper free at one edge, make sure both sides are aligned when laying flat (pins help here), tape the "long edge" together, then slide the PCB in and run it through the laminator.

    The most I guarantee myself with either method is +- 0.05".

    If working with SMD double sided boards, more precise methods are needed. Such as having it sent to a fab house.
     
  19. Wendy

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    Where is the fun in that? :p
     
  20. tyblu

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    Nov 29, 2010
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    Many people get reliable results with homemade boards, either photo or laser print, with 10/10mil DRC. I do 12/10 using photo-etch. Double-sided is not a big step from there.
     
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