Copper Electroplating part 1 (building the tank)

mountedAnodeBanks

When prototyping even small boards at home, dealing with a lack of plated through holes (PTH) is always aggravating. Whether it involves special layout considerations so that you’re not making connections under components (where you can’t get a soldering iron) or spending extra time hand soldering each and every via – not having plated through holes on the PCB’s made at home is a pain. This guide covers how to setup a simple and inexpensive PTH process.

 

We’re going to embark on a journey with the goal of creating boards with PTH at home. Professional board houses use a few different process tanks (chemical baths) to accomplish this, we’ll try and limit our approach to just one, with some mechanical preparation.

 

{snippet chemicalwarning}

 

This build is based loosely from plans you can find from Think and Tinker. We’d like to thank Think and Tinker for the many guides they’ve posted – without them, this build wouldn’t be possible. We’re doing quite a number of things differently (and non-otimally, according to their instructions) based on readily available materials. We’d expect better results if we were to follow their plans more closely.

If you’re the visual type, feel free to check out the image gallery fo this project:

{gallery id=electroplating1}electroplating{/gallery}

 

Fabricating the Plating Tank

The plating tank consists fo the following materials:

  • 1 gallon plastic container (with handle and lid)
  • 1/4″ copper pipe
  • 12 AWG solid core copper wire
1 Cut the copper pipe to length and straighten it out, drilling a hole in one side (the 12 gauge wire will go through this hole later) {gallery link=electroplating1 index=10}solderingTubing{/gallery}
2 We’ll be making two rows of anodes out of the copper pipe. We’re spacing each section of pipe every 1.5″ or so. {gallery link=electroplating1 index=9}tubing and wire{/gallery}
3 Solder the pieces of pipe onto the copper wire {gallery link=electroplating1 index=11}solderedAnodeBank2{/gallery}
4 Cover the tops of the wire and tubing with hot glue. The hot glue will help to protect the copper from gasses in the plating solution, whcih will cause erosion. A propane torch can be used to melt the glue, instead of a standard (wimpy) hot glue gun. Be careful, you can very easily melt the solder if you’re not careful (afterall, these are meant for soldering pipes together)! {gallery link=electroplating1 index=15}torchingGlue{/gallery}
5 Drill holes in the plating tank where you’d like to locate the anodes. Ideally, these would be placed about 3 inches away from center (on each side), but our tank wasn’t big enough. {gallery link=electroplating1 index=19}mountedAnodeBanks

{/gallery}

 

Making Conductive Ink{gallery link=electroplating1 index=20}conductiveInkIngredients{/gallery}

Our conductive ink includes simply waterproof ink and graphite powder. The idea is that the ink/graphite coat the inside of the through holes, making them conductive. When current passes through the anodes and into our PCB (the cathode), the copper in the solution will coat the cathode. But, if there’s no curent flowing into the surface on the cathode, it won’t get coated. Of course, the ink needs to be waterproof so it won’t run when placed into the plating solution. It’s primarily used as a carrier to get the graphite to stick to the through hole walls.

We’ve purchased our graphite from ebay, trying to find the smallest particles we could – to make it go into solution more easily.

 

To make the conductive ink, add around 10 grams of graphite to the 1 oz of ink (the pictuer shows 5 grams, this was later doubled). {gallery link=electroplating1 index=22}graphite5grams{/gallery}

 

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  • weaz

    There is also another way to activate the holes as opposed to using graphite and waterproof ink(the link is just for that).

    http://www.instructables.com/id/Inexpensive-method-of-industrial-level-quality-PCB/

    Please note that this was intended to give excellent results but due to some limitations it is not used on industrial scale.

    Now I have no idea if it works that good but it does sound like a much
    easier way to do it then forcing a much thicker substance trough those
    holes.

    • bamos

       Interesting alternative for the activating solution – thanks for sharing!  It’s worth noting that once the graphite is dissolved into the ink, it isn’t all that thick and flows quite easily.

  • Andrew Frazer

    Started making my tank..  Decided to build it “tough” I hope this is not a design decision i regret.  Here is one of the anodes.  I’m designing a system that can handle an A4 sized sheet.  Im using 15mm light guauge copper tube, and 15mm equal tees, to join it together.  each bar is about 40mm ( 1.5″ ) apart..  I’m also going to braise on some copper saddle clamps so i have a very postive joint to connect the power supply.. Next thing to do is find a suitable tank.. I’m leaning towards buying a glass fish tank, and putting a couple of glass dividers in it so i can potentially have a couple of different process’s sitting side by side..   

  • Andrew Frazer

    Making some progress, i went looking for a suitable container to make the tank from. IN the end i’ve gone for the this plastic chiller box.. ( Chilly Bin down here / Esky in Australia )..  The handle makes for a easy place to mount the cathode to as well.

    • bamos

       Looks great, Andrew.  One thing to note: make sure you allow yourself a way to take the anodes out when the tank isn’t in use (it looks like this will work out fine for you).

      • Andrew Frazer

        yes, easy to lift the anode out,  Whats nice about using the cooler box is that theres a nice sealed lid, that i’ll be able to put in place over the ‘tank’,  to help keep it free from contaimination and stuff.

  • Mathias

    Could you tell me what kind of grainsize your graphite has? Also, have you measured the sheet resistance?

    • bamos

      the graphite I’m using is 44 microns (max) diameter.  By sheet resistance I’m assuming you mean the resistance through a hole after the graphite has been applied -this is several hundred to several K ohms (discussed in this comment: http://twilightrobotics.com/prototyping/electroplating)

      • Andrew Frazer

        There is what looks like an expensive compound that Tink and Tinker sell.. Is it any good? I have yet to try the ink and graphite. really hoping it works well.

        • bamos

           I haven’t tried the compound sold by Think and Tinker, I seem to remember it having a shelf life of only about 6 months – the process you’d follow is exactly the same, so I’d say if the graphite/ink is working don’t bother.  Someone posted a link to a chemical-based activator here somewhere (comments threads can get confusing!)  Some people are reporting the ink mixture being too thick (although I didn’t find this to be the case).  There are also other options for flash plating copper as a means of activation: http://www.instructables.com/id/Inexpensive-method-of-industrial-level-quality-PCB/ (I haven’t tried this)

  • Ted

    Thanks for the really informative tutorial. Some questions: how do you put the ink into the through holes? What voltage do you use?
    oops- never mind I didn’t see the other pages

    • bamos

      I’m glad it was useful, Ted. Give a shout if you have any more questions!

      • Ted Huntington

        Have you thought of any alternatives to ink? For example some kind of
        clear water-proof acrylic? There are acrylic sealers, or perhaps nail
        polishes. Whatever it is must needsto soak into the board. Because ink
        seems somewhat messy. What about a way of really speeding up the
        plating time? Perhaps a higher concentration of copper, a higher voltage
        or current? There is a video where a person plates stainless steel
        without electricity using only a very concentrated solution of
        (presumably-it’s not clear because he says its sodium persulfate) copper
        sulfate and water. https://www.youtube.com/watch?v=WRcf2LO23Fg. This
        person has a similar method
        http://www.homemodelenginemachinist.com/f25/home-copper-plating-steel-without-electricity-1740s-recipe-2834/.
        One last link I found was this person who gets the nanoparticles of
        copper and makes a conductive paint with them with gum arabic
        http://www.youtube.com/watch?v=9iyRUBvd260.

        • bamos

          There are lots of variations on this method. Faster plating times can be acheived with reversed pulsed plating (higher current pulses and occassionally reversing polarity to level out the peaks that form). I’d suggest getting some experience with the simple method first and then adding complexity if you’d like.

          There’s a method somewhere on instructables that’s a chemical-based electroless plating (similar to what the pro’s use). The ink isn’t really that bad to deal with if you’re wearing gloves – a lot less messy that I expected.

  • zikriya

    How to find that water proof ink?

    • bamos

      The ink used in the above tutorial was purchased from a local craft store,you can also find waterproof ink online or from eBay.

      —–Original message—–

  • Andrew Papcun

    What type of solder for copper tubing ? Plumber’s solder is not meant for electric connections unless you are using specific ratio.

    • bamos

      i just used the same solder as i do for “normal” electronics soldering.

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