Etching Tank - Build your own

[killerkev]

Howdy!

Built a etching tank with plexiglass, airstones, air pump, fish tank silicone and tubing. Bought the plexiglass from Home Depot and the other "fish tank" supplies from Dr Fosters and Smith online (You'll save 50% from your local Petco). Helps if you have a friend with a table saw to cut the plexiglass perfectly. Tested it with water before using chemical to test for leaks BUT make sure you use secondary containment! When I used scolding hot water and chemical, she had some small leaks...



The airstones silconed to the bottom:



Don't forget to lock the top! If you fill it up the pressure of the water will make it bulge. Need to lock the top!



A picture with water and boards to etch before chemical addition:



Addition of Anhydrous Ferric cloride:



A picture of the top of the tank...ooohhhh zeee bubbles...

[CodeMonk]

Very cool.
I never thought of those airstones.
Must get some.
Here is what I use :


The secondary container (mainly to catch the splashing and such) is an ice cream container.
The primary is a potato salad container.
Both from walmart.

The black base (the bubble thingy, like the airstones), is a half inch thick piece of rubber from a horse trailer.
It works well, but can be a real big PITA to drill until you get the hang of the proper drilling process.
The pink things are plastic toothpicks (cut to length) to keep the boards above the rest of it just a little bit.

What are the dimensions on that tank?

Edit:
And reading some reviews on various airstones, some people seem to have problems with them actually blowing bubbles over the whole surface of the stone.
Any recommendations or tips on that?
My air pump does 2,200 ccpm.
I'm thinking maybe the people that reported problems had lower volume pumps.

[killerkev]

Dimensions of the tank are 12"x 9"x 2". The air pump is a Fusion 200 model which states output of 1.0 Liter/minute. Your's is more than double the size. It is able to send sufficient air to both airstones.  I believe I bough fine bubble airstones

[Henry89789]

I am thinking of whether to go to the next level in pedal building by getting into etching. Can you all give me an idea of how much money is involved in etching, including buying or building a tank, all the materials, chemicals, etc. Thanks.

[CodeMonk]

My route:
Ice cream container : $5
Potato salad container : $3
But you get some decent potato salad and lots of ice cream.
Tubing and connectors : about $4
Air pump : $10
The black rubber thing : For me, free. But airstones are around $5, often less from what I have seen.
Muriatic Acid : $10 + $15 for 2 gallons I think
Hydrogen peroxide (enough for all that acid) : less than $10 I'm guessing.
Copperclad : Various prices
Laser printer : can be had for about $150, some for less on Amazon or if you hunt around (beware of used ones though. toner costs a lot of money).
Photo paper : $10 - $20 for about 250 sheets.

[Henry89789]

Codemonk:  Thanks for the quick reply. It is not as bad as I thought. I have most of that stuff already even a laser printer and photo paper.  Will a bait aerator work ? I think all I really have to buy is the muriatic acid, hydrogen peroxide and copperclad. what is the best, most inexpensive source for the copperclad that you know about? Let me go do some research to learn about the process for doing this. Thanks.

[CodeMonk]

Not sure about best place for copper clad.
Unless you are near this place : http://www.apexelectronic.com/

I stocked up big time on copper clad there.
Although I don't live near that area anymore and am going to need to buy some in the next month or so.

[Jdansti]

Great idea! I think this would be good for simultaneously etching multiple boards. I've found a way to etch one or two at a time and only use a few tablespoons of ferric chloride.  Fill a plastic container like codemonk shows with hot tap water, then place the board in a quart-size zip-loc baggie. Wearing gloves and eye protection, place a few tablespoons of etchant in the baggie, and squeeze most of the air out as you seal it shut. Keeping the gloves on, submerge the baggie in the hot water. Use something to hold the baggie under the water if the water's too hot for your hand.  I usually face the copper side down to maximize contact with the etchant.  Remove the baggie from the hot water after a couple of minutes.  Rub the copper side of the board through the baggie (still wearing gloves) taking care not to rip the plastic on the corners of the board. Resubmerge and rub again if necessary.

It's not unusual for a tiny amount of etchant to leak into the hot water bath, and it helps to use thicker baggies.  You'd be amazed at how long your bottles of etchant last and how clean an operation this is. 

[killerkev]

I am thinking of whether to go to the next level in pedal building by getting into etching. Can you all give me an idea of how much money is involved in etching, including buying or building a tank, all the materials, chemicals, etc. Thanks.

I think the plexiglass sheet cost less than $10 from Home depot. It is best to have a table saw to cut it correctly as stated. Air pump, tubing, connector, airstones, fish tank silicone - maybe $25 bucks, don't recall. Chemical...depends on what you use. HCL stinks like a bad whore, hazardous to your lungs and all else unless you do it outside, this is why I use ferric cloride. Ferric Cloride is nasty stuff....very corrosive....but does not emit fumes....cost?...Don't know...I can get it from work so no cost to me... likely expensive for others. I make a powerful solution so it's done within 30 minutes. Don't dump it down your sink, it will eat your pipes away. I neutralize and dispose of it properly at work. I purchase mainly from Mouser.com the copper clad boards along with all my major orders. I made this tank to do multipule full 12X9 boards but have not done that yet. The tank can take up to almost 1 gallon of etchant. It can be sized to do less.
Then you will need the the transfer paper to fix your design to the copper clad board. I only use Tecknick Press-n-Peel for this. It is absolutely the best, great prices on ebay for this. I would't bother with the stuff from China that is cheap...you get what you pay for....A great program for design is DIY Layout Creator. If you need help let me know...Glad to help...

[defaced]

Nice project!  I really need to build one of these.  I etch in a Sterilite container and just swish it back and forth by hand.  Low tech and low cost, but I'd really like to find a more "automatic" way. 

Silicone doesn't make a great bond to plexi - you can see if this is the case with the materials you used by doing a peel test on some scrap material.  I figured that out the hard way on an aquarium once.  Given that this isn't a high load application, I don't think it'll matter, but I thought it was worth noting.   

Also, GE Silicone 1 is suitable for making these sorts of tanks.  It's quite a bit less expensive than "aquarium" silicone. 

Copper clad can be bought on eBay from a seller called "abcfab" for a reasonable price.  I have used his stuff several times and I'm happy with it. 

[CodeMonk]

Nice project!  I really need to build one of these.  I etch in a Sterilite container and just swish it back and forth by hand.  Low tech and low cost, but I'd really like to find a more "automatic" way. 

Silicone doesn't make a great bond to plexi - you can see if this is the case with the materials you used by doing a peel test on some scrap material.  I figured that out the hard way on an aquarium once.  Given that this isn't a high load application, I don't think it'll matter, but I thought it was worth noting.   

Also, GE Silicone 1 is suitable for making these sorts of tanks.  It's quite a bit less expensive than "aquarium" silicone. 

Copper clad can be bought on eBay from a seller called "abcfab" for a reasonable price.  I have used his stuff several times and I'm happy with it. 

I recently "made" another tank (I needed one a little longer than the one above.
I had plastic food container, which was a bit larger than I wanted it to be.
I cut 2 pieces of plexiglass to form a smaller section inside.
Then I used a hot glue gun to glue and seal everything together.
Then I used a heat gun to reflow all the hot glue.
Made a great seal.
I even poured hot water in it, and left it sit over night. No leaks at all.
You gotta be REALLY careful with the heat gun though so you don't melt the other plastic parts.


on another note, I bought this stuff today when I was in walmart:



The airstones were $1.48 each, fittings, $1.38, and the container about $3.

I don't have any boards ready to etch yet though

[Henry89789]

I am thinking of whether to go to the next level in pedal building by getting into etching. Can you all give me an idea of how much money is involved in etching, including buying or building a tank, all the materials, chemicals, etc. Thanks.

... Chemical...depends on what you use. HCL stinks like a bad whore, hazardous to your lungs and all else unless you do it outside, this is why I use ferric cloride. Ferric Cloride is nasty stuff....very corrosive....but does not emit fumes.... Don't dump it down your sink, it will eat your pipes away.... 

My concern over these issues is another big reason why I've been hesitant. Does this stuff get dumped after a single use? What is the proper way to get rid of this so as not to damage the environment?

[artifus]

http://www.diystompboxes.com/smfforum/index.php?;topic=50426.0

[Jdansti]

Disposal is another reason to use as small a container as possible for etching.  It takes a very small amount of ferric chloride to etch boards. I ran through a couple of liters of ferric chloride on my first boards until I figured out the three tablespoons in a baggie trick.

Dilution is the Solution to Pollution! 

Not really, but putting a few tablespoons of ferric chloride down the sink with a copious amount of water is like peeing in the ocean.

[CodeMonk]

Another issue with HCL/H2O2 is if you  leave your etching tank open, or don't put it in a sealed container after use, any nearby metal will develop rust, overnight.
I once left my small etching tank open overnight ( An ex-potato salad one ).
About 10 feet away from that tank was my drill press.



That shaft was nice and shiny before that day.
Yeah, it went from shiny to rusty in less than 24 hours.

Oh, and HCL/H2O2 becomes more or less inert if left in a (sealed) clear plastic container in the sun in a fairly short time.
At least thats what someone else in another thread here said.
I don't know if it becomes any less harmful to the environment though.

[bukas]

that is why they call it aggressive acid  xD

[R O Tiree]

It's not just the ferric chloride that's the problem - it's the copper chloride formed during etching. It is water-soluble and bio-accumulative. And it doesn't get excreted out, either. This is bad for wildlife and will get you in deep doo-doo with EPA/HSA/whichever environmental agency applicable to your country. I think EU limits are 500µg/ltr for disposal, which is very low. Legally, I suppose, one could run the cold tap for a day or so and achieve the required dilution, but that's probably not going to cut any ice in court.

Fortunately, the fix is relatively simple. Add NaOH (Sodium Hydroxide) granules a little at a time and you'll find a gloopy black compound will precipitate out. Filter, then test with litmus paper. If still acidic, you'll need more NaOH. If neutral, then you cracked it and you can safely pour the whole lot away. If I remember correctly, you get salty water (NaCl), copper hydroxide (not soluble, so not bio-accumulative) and iron hydroxides (same). During the etching process, copper chloride is formed and some of the FeCl3 gets reduced to FeCl2. So, your "tired" etchant contains 3 different chlorides - FeCl3, FeCl2 and CuCl2. CAREFULLY and a little at a time, add Sodium Hydroxide granules and the reactions below will occur:

FeCl3 (aq) + 3 NaOH (aq) --> Fe(OH)3 (s) + 3 NaCl (aq)
FeCl2 (aq) + 2 NaOH (aq) --> Fe(OH)2 (s) + 2 NaCl (aq)
CuCl2 (aq) + 2 NaOH (aq) --> Cu(OH)2 (s) + 2 NaCl (aq)

(s) means solid and (aq) means aqueous solution.

Be very careful when adding the NaOH - the liquid will boil over in a heartbeat if you add too much at a time. So, you end up with salty water and dark brown goop. solution down the drain and goop in the bin. Simples. If you slightly over-do it with the NaOH, you also end up with a bit of drain cleaner in your salty water, so it's all good.

I think Sodium Carbonate works as well - I know Mark Hammer uses that method, and RG suggested another one years ago in a thread on this very subject.

[Hemmel]

I was thinking of starting to etch PCBs myself and I read a lot about etching solutions. Honestly, the FeCl scares me a bit, the muriatic + peroxyde scares me less...
So, I read the thread artifus mentionned and I'm still not sure how to dispose of the solution once its used. However, I don't think I'll be making 200 boards per week, more like one a month ! And I think I read that you can use the same solution for many boards...

Wouldn't there be a way to separate the copper from the solution after reducing its PH with (for example) baking powder ? Maybe with some type of electrolysis ? That way the neutral solution could be dumped safely and the copper .... errr ... yeah I didn't really think this through...

Also : if I put some etchant in a plastic box, etch a board, then hermetically close the box (to avoid the fumes eating metal like I read)... won't that create pressure inside the container ?

[killerkev]

like others above have said, by increasing the pH of the etching solution from acidic to basic by using baking soda, lime, sodium hydroxide, soda ash.....the precipitate that forms is a metal hydroxide (iron and copper) that will come out of the solution and drop to the bottom. You can then pour the supernate down the drain, scoop out the precipitate and put it in a plastic bag and throw it in the garbage.

[killerkev]

And I think I read that you can use the same solution for many boards...

The etching solution losses it's strength as it is used, pretty quick too! I would never consider re-using etching solution on another day after having treated boards in it already. Try to use a small, high strength amount and dispose of it each time.