DIY PCB Bubble Etch Tank

How to make a home made bubble etch tank for under a tenner!

Bubbly goodness!
First you need

1 tub (pound shop)
1 plastic bin (pound shop)
1 fish bubble pump (£7 inc postage off ebay)
Some rubber tubing (hanging around - or could come with pump)
2 Cable ties
Hot glue gun
Red tape (blue might also do.... yellow may do but have problems - white tape cannot be used :-)
screw driver
Lighter
1 hour of spare time
1 sunny after noon in the conservatory (optional)
got all that stuff? lets bubble!

Step 1: Make the Hole for the Bubble Tube

Warm up the bottom (thats right mindy - the bottom) of the container as this is where we will insert the tube. Were going to put it here because of pressure issues... namely.. we dont want any!

Heat the bottom with the lighter and make a hole this way: i have tried drilling this type of plastic before and it's pretty brittle... this is the safest... but the tubs are only a quid so knock yourself out.

Don't let the plastic burn though as it stinks and will make the hole too large.
When it is ply-able, stick a screw driver through the plastic to make a small hole (roughly the size of the tube). Be careful not to make it too big otherwise it'll be a lot of hassle trying to seal again!

The reason we are going through the bottom and not poking the pipe through the gaping hole at the top of the container, is so that the top can be sealed off with the container lid - for easier storage and transport - plus.. water tight sealing the bottom isnt that hard.

Step 2: Mount the Bubble Tube

The tube will hopefully share bubbles through a lot more than one hole, IF the holes aren't too big. The sum of all the holes if you think about it, cannot be greater than the diameter of the pump's outlet, otherwise some holes will go un-used.


The holes, are just short of 1mm and on an initial test in a glass of water, all seem to function. As a tip, not all holes will output bubbles if the tube is not completly horizontal. This is because of the atmospheric/hydraulic pressures that exist when air is submersed. Ensure this bubble releaser is flat on the bottom

As hot glue doesnt seem to stick to this particular rubber tubing, i've used tape to adhere to it, and then let the glue adhere to the tape (clever huh). Whats even cleverer though is the making of little hot glue bridges that clamp the pipe to the bottom of the container.

Creating the seal is vital! But.. not that hard, just make sure you use PLENTY of hot glue around the joint. If you have more than 1 hour to spare, try sealing it with silicon sealant (the stuff you seal pipes/bathrooms/shower cubicles with). It takes longet to dry but would produce a better (more flexible joint).

Step 3: Pre-test!

Bite the bullet when you think it's cured and add a little! water. If it leaks after 10 mins of sitting still. try again!

Other wise.. Yay! lovely bubbles

The tube should then be bent up and down the side of the container as in picture three. This is so that incase the water tension does break back into the small holes of the bubble pipe, it won't rise all the way back to the pump - saving you WONGA on a new pump! I didn't think it would go back through the holes but it did... left my floor wet on my pre-test - luckily it wasn't the joint that was leaky!

So what do we have so far.... a wonderful fish tank... but we need to make this bad boy an etch tank

Step 4: Board Holder

Now we don't wanna keep dunking our hands in the solution (espescially seeing as FeO3 is sooo bloody staining)... so we make a small harness for PCBs

The harness will accomodate the boards and allow bubbles/currents to flow through.. for this we need out £1 waste basket!

Cut the mesh stuff out of the bin (note the large holes) and fold back on itself to create a small pouch.
At the bottom of the pouch i used a lighter again to soften the plastic. This is so is do not over stress the plastic and make it snappy snap. This way, the plastic moulds to a v shape.

Check the plastic is the right size for the tub and then start attaching it to the lid with cable ties. The lid of the container seemed a lot softer so i just drilled these holes out and stuffed the cable ties through.

Attach the harness loosely to the top so that it is free to move inside the container.

Step 5: Thats It!

Well thats pretty much it!

i mounted my tank on the bottom of the pump for space constraints, an because i had this pipe exiting the bottom end of my container! It now sits as a pretty individual unit

And boy does it' bubble!

maplin.co.uk or rapidelectronics.co.uk has some good etchant. It's a clear etchant that does not stain half as bad as ferric chloride and is MUCH safer!

Maplin code N06CG @ about £2.50 for 0.5L of etchant.
Maplin code MC49D @ about £15 for 5 litres worth.

Plus... if you've made a lovely see through tank... you may want the added benefit of seeing the boards develop before your very eyes!

Next development - add a heater unit (it's on order from ebay (fish heater £6)... but i couldn't wait for it to get here before starting)

Hope you enjoyed
Dandy
www.dandycool.co.uk

Comments

[terezi]

You can also use this chemical etching method to etch metal for jewelry making purposes (designs on the metal that look like shallow engraving), or for knives, swords, etc. types of fine decorative metalwork.
(I found this page in the first place while Googling for info on metal etching for jewelry).

[Expertmurderboy007]

whats that and what do you use it for

[Dandymon]

In electronics, you make circuit boards to hold the components and circuits together. These are called PCBs or printed circuit boards, where the copper track appears to be printed on the board. In real life the board is clad with copper on a side and you use a chemical etch to remove certain areas. This tank holds an etchant liquid and uses bubbles to agitate the solution, allowingany copper board to be etched (quickly)

[Expertmurderboy007]

thanks

[evanwehrer]

I think this could work better if you used a small fish tank and an air pump that can take in air and push it out .(They have them in those little laser levels with the suction thing.) Then you can use a heater. Some fish tanks have a place where you can run a tube down and it will make bubbles go up everywhere. You could also put in a v shaped thing and use plastic grabbing tools to pull it out.

[rh387]

One thing that you could try is get an airstone for an aquarium. It will produce a lot of small bubbles, although I have only seen their operation in water. They are cheap enough to give it a shot though.

[spungletrumpet]

Hiya! I built a similar, but slimmer tank a year ago. I used an aquarium airstone first but after about a week in ferric chloride it completely dissolved! I now use small bore plastic pipe with hundreds of pinholes (made with a sewing needle). This works really well and gives a very even etch. When I build my next tank I think I'll have 2 rows of the perforated plastic pipes, which will mean even more bubbles!

[japala]

Did something similar in 2002.
http://metku.net/index.html?path=mods/bubbles/index_eng

In the next version I pumped the air in from the top of the tank and ran the line down to the bottom from there. This way I didn't have to drill any holes below the waterline thus making it more leak proof.

[Junkyard John]

I was just wondering: could the etchant damage or mutilate the materials used in either of these designs?

[royalestel]

Definitely think you ought to explain what this is used for in the introduction. I had no idea myself when I first read it.

[Mr. Smart Kid]

even a 12-13 year-old geek knows what it is

[royalestel]

Well, I didn't.

[ARVash]

Likely if you've gotten this far with PCB's, you probably understand what this is :P.

[Dandymon]

Right so why did i put the tube in the bottom.... mostly for aesthetics; but very largely so that the top could be screwed on and transported with the liquid in. The liquid is not necessarily safer for you (apologies if i made it sound like it was) but it is much less of a stainer! It is a mild irritant so don't worry about getting it on your hands. As always, never dispose of ANY chemical in the sewerage system as it could harm aquatic life or damage pipes! Pour the waste into screw bottle and dispose normally in the trash is safer. (or evaporate it if you're really concerned). Thanks for all your praise! Hope your projects go well

[Mr. Smart Kid]

btw (UK)pound store = (US)$ store

[GrahamStabler]

Great stuff, I too like the board holder, inspired. A couple of points, the most important thing for an etch tank is a heavy base, knocking one over is a nightmare. So I would agree it would be better to put your bubble pipe in from the top then add some form of stand or weight. Lets not forget what might happen to your hot glue when you add the heater. Secondly if you can get a tub that is rectangular rather than round and relatively thin then you need less etchant for a given size of board, this is cheaper and safer. lastly although the clear etchant might not stain as much it is not safer as such.

[Spokehedz]

Again, the small issue of going in through the bottom/leaks would be resolved if you just put the hole in the side of the tank near the top. Then run the tube down the side and then to your bubbler. There. No more leaks (no fluid anywhere near the hole) and there is no chance of drainage (no tube below the line of fluid). Also, I would put a hole someplace on the lid just to be sure that air can escape someplace. I know you made holes on your PCB holder, but i'd make a smallish one (same diameter as your tube would be okay) just to be safe. That way the incoming air has someplace to escape. A heater may melt the plastic... but there are small small fishtanks up at the pet supply place near me... hmm...

[Aeshir]

I don't get it. What does this do? It looks cool with the bubbles coming out in streams anyways.

[WesDoesStuff]

it's for agitating pc board etchant

[Aeshir]

Huh?