Having tried and failed and wasted too much Laser printer toner, gloss paper and time I have found a method that works for me.
Key notes for success:
- Set the printer properties for max contrast, deselect any Eco Printing options, set graphics options to highest resolution.
- Clean the copper with a metal scouring pad and nail varnish remover or acetone, dry wipe with paper towel.
- Check thrice, apply heat once.
- Apply heat liberally, don’t rush it and get every part of the board/paper area as hot as possible, if in doubt go over again.
- Allow the board to cool before submerging in a water bath to soften the paper for around 20 mins.
- CAREFULLY peel the excess paper away, re-soak for another 20-30 mins.
- Using thumb, rub the excess paper layer away taking care not to be too rough and take the toner away.
- Now check under a lamp and magnifier and correct any bad transfer areas with a fine black marker.
- Heat the Ferric Chloride, I use two plastic Tupperware containers, big one filled with boiling water from kettle and smaller container which holds the Ferric Chloride sits inside the bigger tub which heats the solution.
- Make sure you leave some excess PCB material around the edge so you can drill a small hole for a loop of PVC coated wire or string, this allows you to submerge, agitate and retrieve the PCB from the ferric Chloride easily.
- If some paper/wax off the paper is masking any areas, take the board out and using a gloved finger rub the crap off the board as this allows the enchant to reach the copper.
Here is a picture of the end result of my DDS Voltage Regulator PCB before the tinning process:
After Tinning process….
And the DDS Voltage Regulator Assembly, PCB populated and soldered…
Spot the stupid error – I put one of the mounting holes too close the -5V output from the DC-DC Converter, thankfully I have enough material left over from trimming the board to size so I could offset the hole slightly, other than that works very well.