Toner Transfer

From Projects

After the Printed Circuit Board (PCB) for the design has been laid out in CadSoft EAGLE:

• Select File->CAM Processor. With only "Bottom", "Pads", "Vias", "Dimension" and "Holes" selected, change the Device to "PS" and click the File button to enter a filename. Finally click Process Job to generate the PostScript.
• Open the resulting PostScript file in a program like Adobe Acrobat or GhostView.
• Utilising the fact that toner from a laser printer doesn't properly fuse to glossy inkjet paper, print this PostScript of the final circuit board layout onto Glossy Inkjet Photo Paper. I've tried Epson and HP - both are good. For best results use the proper "Press-and-Peel" paper from Altronics or Jaycar stores. Note: I take no responsibility for any damage to your laser printer by doing this. That being said, I've never had a problem with the papers I have tried.
• Clean the square of blank PCB using abrasive soap and/or steel wool. This removes any skin oils from handling the blank PCB, and roughs up the surface a little so the toner sticks better.
• Place the photo paper toner side down on top of the copper side of the blank PCB.
• With a hot clothes iron, using suitable pressure, iron the toner off the paper and onto the PCB copper. Don't peel the paper straight off when you've finished ironing. Instead, place it in a bowl or sink of hot soapy water and let the paper dissolve for 5 or 10 minutes.
• The blank PCB should now contain the design. If there are only a couple of small breaks in the traces, now is the time to touch them up with an etch-resistant pen. If it's a mess – which sometimes it is – clean the toner off with steel wool and try ironing again with a new printout.
• Once you're satisfied with the design on the PCB, it's time for etching. A tank of bubble-agitated and heated Ammonium Persulphate is best but old-school ferric chloride will do however it's not as good. Watch the etching process closely. Make sure that all of the unwanted copper is removed properly. A good trick is to use a clear container and place a light under or behind the board as fibreglass is slightly transparent but the copper is not.
• The resulting circuit board should now be lacquered with spray-on varnish or special PCB varnish to prevent the copper traces tarnishing. Don't worry – you wont notice it much when you're soldering because it melts.
• The board should now be trimmed to size using a bandsaw or guillotine.
• The holes for components can now be drilled using a standard drill press with a fine 0.8mm drill bit. The holes that need to be larger for wires etc. can be enlarged using a small hand drill or an oxy-acetylene jet-cleaning tool with different sized bits.
• Finally solder everything in and test if it works! Good luck!