I just finished writing up some of the details on DIY plated through holes. This is what the simple constant current source
was designed for. This process was slightly adapted from Think and Tinker
- a really great site for DIY PCB fab. The overall process is:
1. Drill holes in the PCB
2. Coat the holes with a mixture of water-proof ink and finely powdered graphite
3. Cure the ink so it doesn't rub off
4. Dunk the PCB in the electroplating tank, apply current, and let chemistry do the rest of the work.
Here are the pages of interest:
- electroplating (part 1)
- electroplating (part 2)
- electroplating (part 3)
- electroplating (part 4)
Overall, the process is a lot simpler than I expected. Here are some pictures for a quick overview:
The bath ingredients. ..notice nearly every chemical there has a pretty serious warning on it. . .please, take these seriously. . .:
Slopping conductive ink (all over the PCB to "activate" the through holes:
The same board, after getting the top layer of ink carefully removed (for the most part):
Plating in progress, using the simple constant current source
And some plated through holes:
It should be noted that this is something that needs to be done *before* traces are etched into the PCB because the electroplating relies on current passing through the work-piece to deposit the copper ions onto the PCB. If the board is already etched, anything not touching the cathode clip won't plate properly. If you'd like to do PTH's with an etched board, you'll need to pattern plate tin solder or bright tin first (see think and tinker for details). This tin plating will also coat the insides of the PTH's so the copper doesn't disappear, since the tin acts as an etch resist.
The copper doesn't come out all that "bright" (probably because the bath lacks brighteners and anode bags). But, this sure beats soldering individual wires through vias, and I can put them under IC's now without any hassle - all this while still getting my board done the same night!