I etch my own boards and have been using a home made etch tank.
I've used custom made tanks that are almost exactly the size of an arduino board and only require a tiny 100ml of fluid.
The reason is that want to minimize the amount of etchant I use, (ferric chloride). It's nasty stuff, not particularly cheap and is awkward to dispose of.
I've made the tanks out of small pieces of acrylic plastic, but I'm having trouble finding an adhesive that will resist the corrosive powers of the etchant for more than a few months. I've tried a few glues, and the best I've found is arylic sealant (the stuff that come in big tubes for sealing around the edges of sinks and showers) but even this starts to leak after about 60 days.
Can anyone recommend an ferric chloride resistant glue for acrylic plastic?
Perhaps you should fuse the acrylic plastic, so that there are no other materials and all will suffer the same from the etchant.
I googled for 'fuse acrylic plastic' and found some instructions on that, but didn't actually check them out.
Best way would to take a piece of thin-ish plexiglas, heat it in an oven, then deform it to the shape of your tank. That way, there will be no seam to leak. It might look a bit funky tho.
heat it in an oven, then deform it to the shape of your tank.
sounds like a good idea, but probably hard to achieve a good finish in practice.
Maybe try a food container:
I've done this before, but it's very hard to find a container that exactly matches the size of the board being made. I'm trying to keep the volume of etchant down to an absolute minimum.
I use FastBond, "methylene chloride" (causes cancer in California but, used to decafinate coffee every where else).
Just googled this and discovered it's the stuff I used when I re-plumbed my kitchen - I didn't realize I could use this on acrylic, I'll give it a go.
LarryD:
I use FastBond, "methylene chloride" (causes cancer in California but, used to decafinate coffee every where else).
I wouldn't be a bit surprised to find that California has "may cause cancer" labels on bottles of water.
Regarding OP's question - have you tried to use, instead of ferric chloride, a different etchant? Something like:
Now - ultimately, such etchant will become "toxic" - in that it will contain a ton of copper in solution; but there are ways to recover the copper and dispose of it properly. In other words, while "cleaner" than ferric chloride, you still don't want to just "dump it down the sink".
I've also heard that such etchants aren't as quick or such as FC - but it might be something to play around with, as you might be able to make a container that can't resist it better than FC...
cr0sh:
Now - ultimately, such etchant will become "toxic" - in that it will contain a ton of copper in solution
You must do a lot of etching
Seriously, the amount of copper dissolved in the ferric chloride solution shouldn't cause any problems in hobby quantities. In this part of the world all the vineyards are sprayed regularly with copper salts to prevent fungal infection!
pwillard:
I agree. I haven't used Ferric Chloride since the 1990's. Nasty Junk.
I also find that 32% Muriatic Acid + Hydrogen Peroxide is faster than Ferric Chloride and requires no heat to assist with the etching.
Breathing it is not fun. Only do it outdoors. The Etchant solution should not be stored indoors as it will rust anything the vapors touch.
Now that is nasty stuff - much more corrosive than ferric chloride solution. Yes, it works faster than ferric chloride but strong acids need to be handled carefully.
Ferric chloride doesn't need heat to work. Like any chemical reaction the speed of the reaction doubles for every 10C rise in temperature. The alternative is patience.
Muriatic Acid is diluted version Hydrochloric acid... used as a common swimming pool chemical to increase acid level to balance Ph. It's really not so bad.
FeCl aka Ferric Chloride, as I understand it, is actually the effluent from the Steel "pickling" process... which is the process of removing surface rust from sheet steel with Hydrochloric acid before working with it. So the base material is actually very similar.
More asking in general as disposing of old etchant seems to be a nasty affair.
I've not done any home etching nor do I plan to. I'd rather have professionally made boards with reliable vias, silkscreen, labeling, and repeatability from board to board. Especially with more of my designs being done with SMD parts now.
CrossRoads:
Any experience with salt & vinegar etching? Google
Some reputable sites there.
Personally, I just have boards made by iteadstudio.
Salt, dissolved in vinegar, makes a dilute solution of hydrochloric acid, mixed with sodium acetate and acetic acid. It is more corrosive than vinegar alone. Salt and fresh lime juice is about 10 times more concentrated wrt HCl. Lemon juice falls about halfway between.
Kinetic rules apply: the rate of etching is linear with temperature, but it follows the square of the concentration of hydrochloric acid: 2HCl + Cu -> CuCl2 + H2 ; d[CuCl2]/dt = d[HCl]^2 x d[Cu]
(in practice, it's a little bit less.)
