I recently started doing plated-through-hole PCB's, and after using copper wire for my anode for the first couple of boards, I decided to get some proper phosphorised de-oxygenated (PDO) copper anodes.
Whew! Those things are expensive!
So all I needed next was a means of connecting them and suspending them in the plating tank. I didn't want to drill holes in them, so needed something to hold them around the outside.
Commercial anode holders are made from titanium because it doesn't react with the plating solution or get used up during the plating process.
The titanium wire holders shown here are simple and cheap to make, and hold the anodes securely.
Step 1: Materials and Tools
- Grade 5 titanium wire. You can get packs of 5x 20cm lengths on eBay, which is what I did. I think it's actually welding wire.
- Steel tube, ideally about 20% smaller diameter than your anodes
- bench vice
- sturdy pliers
- Cleaning materials for the finished holders and the anodes.
Step 2: Bending the Wire
The anode holders each comprise a coil with bent over ends which holds the anode. The ends actually have a double bend to get better defined planes of contact.
The wire is fairly springy so it needs to be bent around a former about 20% smaller than the actual anodes. I didn't know this and used a steel tube the same diameter as my anodes and had to squash the coils smaller using the vice.
It seems like tough stuff when you bend it, you need to hammer the bends down. I discovered it's also relatively brittle and won't stand being re-bent at the same spot, or twisted where it's bent.
So don't hammer the bends down too neatly, let them be a bit curved.
The following is based on anodes about 25mm thick and about 40mm long.
Bend the end of a piece of wire over about 12mm from the end
Make a second bend up to 5mm further along, perpendicular to the first
I made a notch in the end of my steel tube so the end of wire sits in it, to help hold it in place, but I'm not sure it made much difference.
Using a bench vice, clamp the wire against the tube so the end section sits across the end of the tube and the next short section lays along it.
Begin coiling the wire around the tube. Hammer the first quarter turn into place or you may find it has a straighter part at the start. You need about 2 full turns. I found the coil naturally ended up being about the length I needed anyway. If in doubt try to wind it shorter.
Remove the wire from the tube, check the anode fits in it. If it's tight, great, if it's loose, you will need to squash the coil smaller using the vice. Go around it in small stages, squashing by small amounts.
Going back around the coil a little from where you finished (to avoid a straight part at the end), bend the remaining wire out parallel to the axis of the coil, then up to 5mm further on make another bend so the wire crosses the end of the coil.
I found I still needed to bend the end of the last turn a bit more using pliers.
Finally form the end into a hook to hang on the edge of your plating container.
Step 3: Cleaning
Now the wire has picked up all kinds of rust and crud and steel particles from your bench and tools, and grease and acid from your hands, you really don't want to go putting it in your plating bath!
Clean the holder in the same way you would clean an item for plating:
Scrub it with detergent (I used a wire pan scrubber for this)
Wear gloves for the next part!
Soak it for 15 minutes in caustic soda (lye)
Pickle it for 5 minutes in hydrochloric acid (I swished it around since I only keep a small amount of acid ready to use)
rinse very thoroughly.
There are more advanced ways of cleaning but I am a beginner and this is what I know.
I also gave the anodes a good clean, but didn't use the acid on them
To avoid contamination, you shouldn't handle the anodes or holders with your bare hands after this.
Step 4: Deployment
Now your wire is nice and clean you should wear gloves for this part...
Squeeze the anode in past the straight part at the hanging end of the coil.
Hang them in your plating bath, connect them up and off you go :)
You can also admire how they look like metal swans...