PCB Etching

[mkruger]

So I finally made a nice etching tank today with an aerator and heater. Its 6"x12", all glass, with a lid. Holds about 2gal but I only pour in one gallon at a time (Ferric Chloride). Total parts cost was about $45 for nice gear purchased at Pet Warehouse. I have a few questions:

What temp should I keep the Ferric Chloride?

What are your thoughts on adding new liquid to used liquid?

Does anyone know if the other two etching solutions last longer or are more reusable?

-mike

 

[CJ]

45 to 50 c.
The other stuff is lless messy and works faster. Plus, you can see thru it so you can tell when you are about to fry trac3s. Man, thats a lot of fluid, but it will last a longer than fluid in a tall thin tank.

 

[PRR]

> What temp should I keep the Ferric Chloride?

http://www.kepro.com/inst-e.pdf

110F, about 43C. "DO NOT exceed this temperature or excessive fuming will occur."

http://www.p-m-services.co.uk/the_process_s.htm

http://www.web-tronics.com/fechpo4.html says "Etching process can be sped up by heating the solution to a temperature no higher than 55°C (135°F)."

http://www.mgchemicals.com/products/415.html

Fresh Ferric Chloride is nasty stuff, but used Ferric Chloride is VERY nasty because it is full of metal. You shouldn't dump it down the drain: it eats copper plumbing just like it eats PCBs, and also it poisons the sewage plant and the river/sea it goes into. Possibly a hobbyist quantity flushed with a large amount of water is not a big deal, but you should find out if there is a better place to get rid of it safely.

It is possible to remove the metals, filter, and recycle Ferric Chloride. However Los Alamos Labs, who used to dispose of 8,000 gallons/year of the stuff as "hazardous waste", and is surely qualified to recycle it in-house, returns it to the company for recycling. If you want to ship it to California, look for Phibrotech. But they probably don't want to deal with small quantities from strangers. And there are special rules for shipping stuff like that.

 

[mkruger]

The reason I was using Ferric Chloride is because I buy liquid Gallons of it from Allied, (made by MG Chemicals). I fill my tank with a gallon at a time. Does anyone know where to get gallons of those other two chemicals?

-mike

 

[Vetsen]

http://www.web-tronics.com/amper2241.html this is one alternative

Vetsen

 

[FrankSL]

I actually use "The dirty way" described on Jakob's site, with HCL and Hydrogen Peroxide and it works perfectly even without heating (the chemical reaction makes the solution warm by itself).

You really have to pay attention to what you do with these chemicals!

I also use standard white paper and inkjet printer for UV exposure and develop in a solution of water and NaOH (sorry I'm not a chemister and I'm not english, so I don't know the exact commercial names of these products).

Frank

 

[CJ]

CircuitSpecialties.com.
Amonium Persulfate or Sodium Persulfate.
1.1 kg of SP will make 4 liters.
But over time, it will pecipitate into a bunch of crystals on the bottom of the tank.
That is why I use a thin tank.
And yes I get funny looks when weighing this stuff out on the parts scale.

As I mentioned, you can monitor the process easier with the clear stuff.

 

[mkruger]

All the sudden I'm having trouble with my Press-n-Peel process. I'm used the same temprature, same iron, same PCB, and same printer as I did before but for some reason the stuff is not sticking very well. The only difference is that i'm trying to make a bigger board, 6x10. I used to only make 4x6. I wonder what could be wrong. I'm really pissed because I just went through $15 worth of Press-n-Peel at different temps...

 

[CJ]

I spent a fortune on stuff that did not work well. Finally, after many faiilures, I got some repeatability in the process. Everything gave me trouble.
Finding the right printer to print on vellum without paper jams or incomplete traces. Then there was the cheap surplus store chemicals that were so old they did not work well. Then there was the lame stick on traces. Then there was the cheap Radio Shack boards that I tried to save a buck on, then there was ferric chloride at room temp that would sit for 24 hours and do nothing, ..... :twisted: Weeks and Weeks. And $$$$!:evil:

My final procedure is

Vellum art work printed on a HP Laserjet 3.
MG Boards
UV Light box
MG developer and etchant-Sodium Metasillicate
MG Etchant-see above post
Circuit Specialties etching tank.

 

[mkruger]

i think i might try the UV Light box method, just to try new things.

But first i'll waist the rest of this press-n-peel stuff. I'll try a cloth in between. I don't know why cleaning the board any differently would make a difference... but i'll try scotchbright instead of the #00 i was using. This is all very discouraging.

I started this project a year ago and I work on it almost every day. I had planned to spend $600. Well $4,000 later I'm basically out of money, but If i can just make my circuit boards then my mic preamp will be done! :? In a way I don't want to finish the project... this has been one hell of an experience. And when i'm done i'll just be a guy with one kick ass mic pre, no money, no job, no girl, and no place to go. What then?

 

[FrankSL]

I forgot to tell that to clean out the board after etching and remove the photoresist I use standard alcol (that pink one, ethilic I think), and this leaves all the copper on the board.

Apart from the hydrogen peroxide (here we call it something like "oxigenated water") which should be very concentrated to work well (but I found it also at a DIY store), everything I need for the process is available at standard stores near my (and everybody's) house.


Frank

 

[daArry]

I get much better results with laserstar paper then pnp blue - cheaper and u can also use both sides Just iron on with a peice of kitchen paper on top...

To clean the copper brd I just use steel wool...

BTW, I bought a cheap Samsung ML1210 (had nightmares with the old HP laserjets) for like a nifty and have not had a single print fail...

 

[mkruger]

rf, what do you mean by 3rd party toner? that could be whats wrong... I use a printer at my school. Maybe they put a new cartidge in and that's why it's not working!

If I were to buy a printer what do I look for in toner, what company, etc...?

 

[daArry]

I should of said 'film' rather then paper if your searchin...just had a google and cudnt see any hits for US supplies...shud be able to get some sent to ya from wherever tho no? Rapid, RS and Mega stock it and should send outside UK...