Introduction: White Glue Release Agent for PCB Toner Transfer
After spending two and a half months of concerted effort trying various methods of transferring artwork to a copper clad board; I have recently discovered a simple, low skill method of doing so. The result is a transfer which looks like an art project, and is so simple that I simply must share.
Here is the simple:
Coat your transfer paper with Elmer's White glue and let it dry.
Flatten the sheet out so that it won't jam in the laser printer.
Print on the sheet
Heat transfer the image to the substrate.
Step 1: What I Used
In lieu of stating what you need, I am just going to say what I used.
- HP LaserJet P1102W (Laserjet printer)
- Swingline GBC 3100L (Hot roll laminator)
- Elmer's White Glue
- Speedball squeegee for silk screen printing. Any flat, straight rigid edge should work, however this is what I had so this is what I used.
- 600 or higher grit sand paper. The higher the better. The intent is that if you need to clean the surface best to sand it. Further, it seems to create a textured surface for the toner to adhere to.
- Tarn-X Tarnish remover. This is to remove any tarnish from the board. This stuff smells.
- Acetone. Depending on what you are doing you may or may not want to remove the toner after wards. Also it helps to clean the board to remove any oils.
- Dish washing liquid. Also to help remove any oils
- Latex gloves
- Work gloves. This is for handling the hot board. You can use oven mits or other insulating gloves if you have them. If you hands can take the heat however then you don't need it. You will however need the latex gloves so that you do not touch the cleaned board.
- Container of water. This is for cooling the board and encouraging the release of the white glue.
- Paper towels, for cleaning the board and keeping the workspace tidy.
- Copper clad board
- Transfer Paper. This can be standard plain paper, glossy paper or photo paper. Yes, standard paper works as well. I will explain the limitations and reasons for each type of paper further down.
Step 2: Coat Your Paper
I mentioned that you can use standard copy paper to do a good toner transfer. However it has an up side and a down side. The upside is that it comes over easily; in one piece if you are careful. The down side is that it leaves pinholes! I had long thought that pinholes in the transfer were because of the limitations of the laser printer, however in my recent experience I believe this is not the case. I now believe that pinholes are because of the texture of the paper used in the transfer. If you use glossy paper you will get fewer pinholes but it takes longer to come off. If you use photo paper it takes forever to come off. Photo paper is designed to be water proof. While the photo paper is the hardest to remove and never comes off in one piece; I have noticed very few pinholes in the resultant transfer.
Regardless of the paper the coating process is the same. The technique used is the same as coating a silk screen with photo emulsion. This is solely to get a smoother finish.
I recommend you practice with the plain copy paper until you get this step correct. Apart from cleaning the copper clad, this is the hardest step.
- Squeeze an even line of glue onto the paper in excess.
- Drag the squeegee over the glue across the paper slowly so that the glue gets a chance to soak into the paper (if plain paper).
- If the glue did not coat enough of the sheet then you did not put enough glue; throw out the paper and repeat. Try not to build up too many thick coats onto the sheet, as this will make the glue thicker in some places and thin in others.
If you feel adventurous, you can keep coating the paper until you get a smooth finish in all directions, but be advised that the water in the glue will warp the paper.
- Let the glue dry. You can make a number of sheets at once and keep them in a dry place for future use.
Step 3: Optional Step: Flatten Paper
How you flatten the paper can vary dramatically from using books, to ironing to passing through the laminator. I use the laminator on cold. What ever you do DO NOT use heat.
- With the laminator on it's cold setting, pass the sheet through. This will flatten it somewhat to prepare it for the laser printer, so that it does not cause a paper jam or distort the final image.
Step 4: Print Artwork
- Load the glue paper into the laser printer and print your artwork on the printer's highest quality settings. For me this is the FastRes 1200 mode.
Now you will have laser toner separated from the paper by white glue.
Step 5: Clean Your Copper
Never touch the surface of the copper with your oily hand. Use latex or rubber gloves when cleaning and handling the boards. This is a critical step that affects the quality of the transfer above all other factors.
- If the surface of the copper is very damaged, it would be best to just sand paper it with a fine grit sand paper to remove the damage.
- If the board has oils on it then clean it with dish washing liquid.
- If the board was used in previous attempts at toner transfer, the use the acetone to remove all the old toner.
- If the board does not have a bright copper coat then use the Tarn-X to remove the tarnish. Be sure to read the warning labels on the Tarn-X before use.
While I used paper towels to clean the boards, any non fibrous material will suffice. You will know the board is clean when water sticks to it. If you wet the board and tilt it so that the water falls off; the water should not completely fall off. There should always be a thin "film of water" on the surface. Any spot that does not have this film is not clean. Redo accordingly.
- Dry the board and keep in a bag with all the air removed. The less oxygen the copper is exposed to, the slower it will tarnish. I have noticed that when the Tarn-X is used the copper begins to rapidly tarnish. After just one day in the open air the board had to be cleaned again.
Step 6: Laminate
The board will be quite hot during/after this process so adorn your heat gloves if you need them.
- Cut the paper to the size of your copper clad board
- Place the paper on top of the board with the copper side up
- Set the laminator to the 7mill pouch size. This will feed it through slower than the 3 or 5 mil
- 1st Pass through the laminator. Do not force into the laminator. Once it grabs just let it be. The paper will stick to the copper surface (like a sticker) by the action of the white glue. While I am unable to confirm this, I believe that both the glue and toner are melting. The glue fuses the paper to the copper, intrinsically prevents you from distorting it during lamination.
- 2nd Pass through the laminator. For this pass turn the board around. This is to ensure that the entire board is heated.
-3rd Pass through the laminator. This time flip the board over so the copper/paper side is down. Again to ensure even heating.
Safety Note: Never leave your laminator unattended or running while you are not using it.
Step 7: Quence and Peel
- Douse the board into the water and let it cool. Wait until the board is cool and the paper is soaked.
- With the latex gloves on, begin to peel off the paper from the board. If you used regular copy paper then with a little patience and slow peeling the paper will come off in one piece. If you used glossy paper or photo paper... you are going to have to work for it. The photo paper will most likely come off and leave a thin white plastic like film on the surface. Gently rub this film off the board. It takes me 10 minutes to soak and remove the photo paper.
- Once the paper is off, rub the surface of the board so that any glue residue is remove as well. All the glue should "dissolve" into the water. Dry off the board (or let it air dry).
- If not etching right way then keep the board in an air tight location (e.g. zip lock bag or container) until you are ready to etch. I use muratic acid + hydrogen peroxide as my etchant. It is a little dangerous but the environmental benefits are hard to argue with. If you are using this etchant, I personally recommend that you do this outside and stand up wind of the solution.
Step 8: Conclusion
I suppose this method can be used to transfer to other substrates than copper (such as aluminum or glass). This method can be used as artwork (as seen in the photo) or for Printed Circuit boards.
It may also be possible to transfer colour toner to a metal substrate to emulate dye sublimation printing on metal plates, tiles, glass, wood etc. so this process is not strictly for making printed circuit boards.
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