Why Wait? Just Plate Your Own PCB Vias

[Jan Mrázek] is a pro when it comes to rolling his own PCBs. He can crank out a 6/6 mil double-sided PCB in 45 minutes flat. As a challenge to his prowess, he decided to experiment with plating through-hole PCBs at home, because sometimes you just can’t wait for China to deliver the goods.

The key here is to make a non-conductive surface—the walls of holes drilled in a sheet of copper clad–conductive. While there are some established ways of doing this at home, the chemicals are difficult to source. When his local supplier started stocking colloidal graphite paint, which is used to prevent ESD and fix non-working remote control buttons, he decided to try it.

[Jan] drilled up a board with holes ranging from 0.1mm up to 8mm, polished it, and gave it an acetone bath. He sprayed each side with graphite and cured it at 100 °C for 20 minutes. At this point, wall hole resistance measured 21 Ω. [Jan] wet-sanded away the graphite and set up an electroplating bath. Right away, he could see a layer of copper forming on the holes. After 90 minutes, he polished the board again and separated the vias to prepare for the real test: solder. This time, every hole except the smallest size reported a resistance of 0.1 Ω. But they all sucked solder through the vias, making this experiment a success.

[Jan] concluded that this is a simple and effective process, but is rarely worth the effort. We wonder how the simplicity of this method compares to drilling wells instead of holes, filling them with conductive ink, and then drilling the rest of the via.

Via [Dangerous Prototypes]

34 thoughts on “Why Wait? Just Plate Your Own PCB Vias

      1. Actually, last time I needed conductive pencil, the Staples brand HB won, and there was a Conte I think it was 2B artists pencil that was barely registering. So “good” not necessarily conductive.

        1. Me too. They’re sold by the inner diameter, and the outer diameter is 0.2 mm bigger. 0.8 mm is a tight, but possible, fit for pin headers, and you have to drill out at 1 mm, and the flange is at least 1.2 mm.

          The sell a press for a bazillion dollars that goes along with the rivets, but I haven’t ever needed it. I just solder on both sides and trim the waste. I suppose with the press, I could skip the soldering altogether…

    1. I have learned: lace up the whole board with a single piece of wire, through all the vias, solder both sides, then clip the wire. It really, really beats trying to stick little snippets of wire into each hole and then having half of them drop out when you’re trying to solder the other side and you melt the solder on the side you just finished.

  1. graphite powder mixed with acrylic paint works a treat for this. I use it regularly for plaiting 3D printed ABS parts.
    I find you do have to experiment a little with the emulsion depending on the supplier of the graphite and how fine it is but the best stuff I have found is the stuff used to lubricate locks.

    Oh and just for kicks I used an acetone/ABS/grphite mix and found that works really well however its not easy to spray on the surface as it tends to dry in the airbrush and clog it.

  2. This is the way! Having played with graphite before, I found that Nickel paint is even nicer ( MG Chemicals 841AR ) as the initial resistance is lower so more copper settles on the holes faster. Not sure if the particle size is larger; I haven’t tried that on super-tiny holes, just like 0.7mm.
    As for coating, I just put little droplets on the vias, then suck them through with a vacuum cleaner on the other side which typically covers the hole-walls nicely (repeat from other side for good measure).

  3. FWIW, unless he was measuring with a 4 wire meter there chances of him measuring resistance accurately in the .1 ohm range are slim to none. I am willing to bet the resistance was way less than that.

  4. You really need a CNC drill to do it though, as all the tracks need to be connected to do the electroplating. At a pinch you could maybe print a drill guide and stick it on to drill but it’s going to be a fiddly process

  5. If you want cheap, readily-available conductive ink, many India inks are conductive. I use Speedball Super Black for this exact purpose — available pretty much anywhere art supplies are sold.

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