PCB Etching (again!) - chemicals used

their

so try using toilet cleaner, the ones with HCl in them.

NT

Yeah, but that's only in the south, I prefer it up in the tropics where it gets above boiling point ;-)

Cheers.

I read in sci.electronics.design that Chris wrote (in ) about 'PCB Etching (again!) - chemicals used', on Tue, 26 Apr 2005:

Back in the Dark Ages, 1948 to be precise, my school's magazine included a report from an Old Boy ('alumnus' in US English) from 'British Malaria', where the LOWEST ambient temperature was inside the boiler of the coconut-crusher's steam engine.

--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

I had forgotten that you can get ahold of oxalic in consumer products. What about oxalic with a catalytic amount of KI, and some as yet unidentified reducing agent? I'm thinking of the greensalt synthesis.

EDTA may work even better than oxalic. EDTA constants are mentioned on

It used to be a component in Mr. Bubble, but I haven't seen it on any labels in the past decade or so.

I read in sci.electronics.design that "Aubrey McIntosh, Ph.D." wrote (in ) about 'PCB Etching (again!) - chemicals used', on Fri, 29 Apr 2005:

Rhubarb, rhubarb?

I don't know the term 'greensalt synthesis'. Google doesn't help much.

Oxalic acid just forms colourless, soluble ferrous oxalate, I think. Doesn't EDTA form complexes with Fe?

--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
\'What is a Moebius strip?\'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

A cleaning material for wooden decks contains mostly oxalic acid. I have forgotten the brand name. When I read the price and the ingredient list on the label, I thought a while, bought a stiff brush and a gallon of vinegar, and the change in my deck was just short of miraculous.

No, I couldn't find it either. A few years ago there were dozens of lab write-ups with the name, but it is archaic.

The formal name is potassium tris (oxalato) iron (III) trihydrate or alternately potassium iron(III) tris-oxalate hydrate. It forms large clear emerald green colored crystals. The color change is when the solutions are mixed is immediate and dramatic, so it makes a nice freshman chemistry lab. The toxicities and mess are low.

My memory was bad, it should be iron(III) and not iron(II) to be soluble, so it should be easy.

There is a nice picture of the structure of the compound in this lab manual:

A fairly short description of a synthesis, using Fe(Cl)3 is given at

My thinking is that the oxalate's oxygen will grab the iron away from the rust's oxygen, given good conditions. Also, the color change gives immediate status on success.

A compound with a central metal atom and other moieties around it that have "lone pair electrons" is a "transition metal complex," so they both the oxalates and the EDTA are correctly called "complexes" or alternately "chelates." The oxalate is a "chelating agent" or a "ligand."

The key to having them be soluable is to have the complex carry a net charge. So, if I made oxalates using Ni, Cr, Fe, Co, and try to walk across the periodic table, I do end up with some beautiful colors, but some are solutions and some are gunk.

I read in sci.electronics.design that "Aubrey McIntosh, Ph.D." wrote (in ) about 'PCB Etching (again!) - chemicals used', on Fri, 29 Apr 2005:

I found another 'green salt' with Google, Pt(NH3)3PtCl4. Nice, if you can afford it!

That's helpful. But I'm not in favour of this niminy-piminy semi-micro stuff. Let's have gallons (Imperial, of course) of reagents!

[snip]

Chelates hold on at both ends. They are a sub-set of complexes. Ammonium and CN complexes, for example, are not chelates.

Maybe even more fun with trans-uranics, but use a very long spoon!

--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk