Pump for ferric chloride

[DocStein99]

I want to make a nice tank to test my etching.  I think a verticle rectangle box, with a long air bubble stone at the bottom - looks like it works good - or maybe a recirculating pump to make a waterfall down the board.

I was looking for advice from people with more experience.  I used to just put this in  bowl with nothing but the ferric chloride and impatiently shake and tilt it while I make a mess.  I rather make something more tidy.

[tinman13kup]

I found heating the acid and floating the board the easiest. Normally only takes a few minutes, and with single sided boards is easy to see when to pull it.

On double sided, I used a plastic slide clamp to suspend the board. I found this giving much better results than putting it on the bottom. Again, heat is the key, but not too much. I tried using an aquarium heater once. If you are heating a large amount of acid it would work fine, but mine wasn't. I got sidetracked for 5min and when I returned to the garage and opened the door, I found a fog quickly taking over the garage. That was interesting. Now, I fill the sink with hot tap water to warm it.

[Grumpy_Mike]

I think a verticle rectangle box, with a long air bubble stone at the bottom

Make sure it has a lid. Each tiny bubble as it pops on the surface takes a very small amount of ferric chloride and flings it a remarkably long way. You only find this out later as things quite a distance away slowly corrode in holes.

[tinman13kup]

I read an in depth article on etching brass trains. They use the same processes to make the parts. They use peristaltic pumps with spray nozzles with the part being suspended. It was surprisingly fast. The theory was the spray removed the oxide layer giving good uniformity. They also used aquarium heaters in a sump holding a couple gallons of ferric chloride. I'm thinking they were shooting for 110 degrees F, but I would research that.

[DocStein99]

Ok, the spray-onto method sounds good.  I can just heat a resivoir and pump that into some tubes aimed at the board. 

I have to play some fun games to see how many months of failed attempts it will take me to print inkjet resist a pcb pattern.  I thought to mix RAIN-X into the UV pigment so the etch pattern would repel chloride like it does rainwater on winshield.

---
I should fill my winshield fluid with ferric chloride and aim those nozzles to spray my appreciation on the back of every car that quickly cuts me off, and hesitate while texting & driving.

[tigger]

Ferric Chloride is ferociously corrosive.
I've done PCB etching with it and used it industrially in water treatment.
A colleague in the waste water business thought it would be clever to empty a ferric chloride tank using a submersible stainless steel pump. Within about an hour, all that was left of the pump was the cable.
In some ways, it is worse than free hydrochloric acid, and maybe the iron acts as a catalyst, but it eats stainless steel.
Plastics will survive, but nylon will get consumed. Thermo-plastics like the polyolefins are inert as are silicones.
A silicone tubing peristaltic pump might be the safest.
If you do get stains (highly likely), oxalic acid reputedly removes them, but never worked for me.

[DocStein99]

I have a gallon of MURATIC acid, I can also test with too - hopefully it works.  It will save me having to special order ferric chloride - since RADIO SHACK is closed and I can't buy from a store.  Unless it is a hardware store item.

If a hardware store DID sell that what is it's purpose other than etching copper PCB?  Maybe the automotive store have it - they use to remove rust?  Can C-L-R also be used?  I used the C-L-R on rusty crap and it seemed to clean it up really fast.

I really do not care if I have to smash up APPLE-JAX cereal and use that.   Whatever can etch this copper and play nice with this inkjet output on the Epson C80.  Or my laser etching machine - whichever I can get done first (at the MERCY of post office delivering my parts at 3 entire weeks).

I ordered a couple of these $6.00 peristaltic pumps on eBay.  Looks like a motor with some plastic thing that spins around a tube.  Self priming so I can hopefully rig something up externally without submerging a filthy pump in the fluid for it's filters to get clogged. 

Hopefully I can also be using these same pumps to wash out and maintain my ink-delivery system I will build to the C80 print head.  I spent about 20 hours researching the BEST inkjet printer to cannibalize.  The C80 is the oldest and cheapest that uses PIGMENT inks.  The head is the least expensive of all the epson printers to replace as new part.  Since it is the oldest, there is plenty of nice software to trick-out the dumb EPSON ink-scam alert for low ink.  Unfortunately I was not able to find anyone who tackled the task of hard-wiring the ink-chips directly to the carriage, bypassing the on-board ink level firmware.  I was also unable to find open-source firmware for the head, to trigger the nozzles manually - for someone to open-build their own inkjet printer.  The system does exist for other inkjet heads that start at $180.00 each, so it's not really a fun toy to play games with trying to print different fluids, like a dichromate-uv reactive with resin (that I intend to do with the epson head).

[allanhurst]

1/  Muriatic acid is another name for plain hydrochloric acid - if concentrated it's fumes will make you cough and splutter, but it doesn't eat copper very well.

Nitric acid does, but it's much nastier and the fumes ( Dinitrogen tetroxide) are very poisonous.

2/  In the days when I etched my own boards with FeCl3 I had a plastic tub rocked by a cam on an electric motor.

3/ Professionally made boards,with solder resist and silkscreen are so good and cheap these days that I don't bother.



Allan

[tinman13kup]

As for the peristaltic pump, yes, it is a 3 lobed cam that rotates, crimping the silicon tube as it rotates. If you have ever been in the hospital with the IV hooked up (somehow I think you have been with some of your projects), that is how they operate. (same thing). You can put a fixed voltage for a fixed output, or pwm it for variable flow.

You can get more tubing so you can leave the one used for acid just for the acid. Mixing chemicals in a tube willy nilly can cause issues if the wrong 2 come together.

Hydrochloric  acid is good for ferrous metals, while ferric chloride works on non.

[DocStein99]

3/ Professionally made boards,with solder resist and silkscreen are so good and cheap these days that I don't bother.



Allan

PCB service is either FAST or CHEAP.  If I am too impatient to wait 3+ weeks to deliver my boards, by that time I will have already re-designed it many more times.  I am not wealthy enough to afford the speedy service to produce boards that are larger than a silver dollar, DIP size - since I do not own ANY SMD size components.

[CrossRoads]

Have you tried other etching methods?
http://www.instructables.com/id/Is-the-best-PCB-etchant-in-every-kitchen-/
Vinegar+salt+hydrogen peroxide
Plenty of other links discussing this are on google.

I only buy boards that I designed, double sided with plated thru vias and silk screen and stenciling.
I use iteadstudio.com as my source with boards I design in Eagle.

If I'm doing a one-off board, I'll wirewrap one up on island of holes perfboard.
Outside of that, it's a batch of 10 or 5 PCBs from itead.
See examples here
http://www.crossroadsfencing.com/BobuinoRev17/

[DocStein99]

Thank you for the interesting chemistry link.  I love to save money, and those simple kitchen ingredients make it easy.  The page is informative.

I see you make good work designing the boards.  Once I can complete and finish any of my never-ending projects, I hope I can grow up and send my board designs out too. 

[AdeV]

According to Something I Read On The Internet (so it must be true, right?), a mixture of Hydrochloric acid (HCl), Hydrogen Peroxide (H2O2) and copper makes Cupric Choride, a greenish liquid which (allegedly), just loves to eat copper... The HCl+H2O2 is suppose to be pretty keen on copper too... and the CuCl2 (Cupric Chloride) can be regenerated by bubbling air through the solution once it's worn out (i.e. it's eaten so much copper it's all CuCl rather than CuCl2. And, occasionally, throwing another glass of HCl acid in there....

Obviously that's all a bit vague - here's an example from t'internet: http://www.instructables.com/id/Stop-using-Ferric-Chloride-etchant!--A-better-etc/

I plan to try this before falling back on Ferric Chloride, because I know what a bloody mess FeCl3 makes if it a) spills, b) splashes, c) gets within a metric yard of clothing, etc.

[tigger]

Crossroads
Nice to see someone else using wire wrap - a much underestimated technique.
As I sit here, in front of me, I have a wire wrapped XBee on an FR4 perf board. With 20 pins on the XBee, It looks like a rats nest, but it works and no unwanted capacitance. Four reels of 30-guage Tefzel coted wire and an original OK wrapping tool. And dead easy to correct.
Male PCB header pins make great wire wrap pins. I recently found the "Manhattan" style of PCB work. That is a labour of love, but still favoured by the die-hard RF guys.

Ref the hydrochloric acid and hydrogen peroxide, these are getting trickier to get in the UK thanks to them being used for less useful things than PCBs - in a recent terrorist attack, the bomb-maker had been round a lot of hair-dressers buying up the high strength peroxide and I understand that HCl gets used for cocaine purification.

Being a bit more resourceful, you have to look further afield and 32% HCl is still available as a drain cleaner in some hardware shops, other than that, the building trade use it to clean mortar off brickwork.

Nitric is nasty, but not half as nasty when you mix 3-parts HCl to 1-part nitric and end up with aqua regia, the only acid I know that dissolves gold. The one I respect the most though is Hydrofluoric.

[pwillard]

I haven't used Ferric Chloride in over 10 years and I make board all the time.

You only need the severely watered down Hydorgen Peroxide you find at the chemist designed for medical use.  You don't need the hairdresser strength.

The Muriatic Acid is still a pool chemical so should be easily available...

This is the only method I use now, as it requires no heat or bubbles just a little rubbing with a paper towel in the non-opaque liquid to be sure the etching process is done.