pcb etching tank

[unclejed613]

back in the late 80's i was working for a company that built prototypes and automated test fixtures. one of our projects was for a military contractor, and i suspect that it was an etching tank, but i'm not sure. it was made with a solid block of aluminum, about 10"x15"x15" milled out to form a tank. the aluminum was finished with a hard-shell black anodized finish that had some teflon in the formulation, so it was chemically inert, and the finish was so hard that it couldn't be dented with a hammer and was VERY scratch resistant. our job was to install the heater elements in holes bored into the base parallel with the bottom. the whole thing was mounted on a wobbler table and an electronic temperature regulator and motor speed control in the wobbler chassis. whether for mixing chemicals, cleaning or for etching, these (we made 3 of them) beasts were expensive for whatever they were made for.

 

[Boncuk]

How many hobbyists do you think use that chemistry?

I guess there are a lot of them in Europe since that stuff is the only one most electronic shops offer for etching - besides iron-tri-chloride.

Just a question: Are you trying to pick on me? If yes that is definitely the wrong address!

Boncuk

 

[unclejed613]

ummmmm......
"Iron(III) chloride, also called ferric chloride, is an industrial scale commodity chemical compound, with the formula FeCl3. "

could also be written as "iron tri-chloride"

it just so happens that out of iron's two stable valence states of 2 or 3, that chlorine likes 3 when the temperature is below 300C



interesting side note:
i used to have a cat that for some reason would not stay away from my etchant tank. i had to keep the cat locked out of the room where i kept it, because this cat would do anything to get to it. more than a few times i would find the cat had somehow gotten in and was lapping the stuff up like milk, and i would chase him away, lock the door and spend an hour or so watching the cat for anu signs of discomfort etc... which never happened. mind you the etchant the cat was drinking was used etchant, and so was a mixture of iron chloride and copper chloride, and was MORE poisonous as a result, but this cat would fight to get to the stuff, and never suffered any ill effects...... i guess cats can digest just about anything?????? i don't know, but that's always puzzled me........

 

[Sceadwian]

I'm not trying to pick on you Boncuk, I'm from the US. I've never even heard of Natriumpersufate. I found Sodium Persulafate. I think we're having language clashes =)

As Unclejed said the most common (cheap and easy) chemical used for etching is Ferric chloride.

 

[unclejed613]

"Natrium" is the latin name for Sodium.... it's where the chemical symbol "Na" for sodium comes from.

 

[Sceadwian]

Same thing with iron trichloride being ferric chloride. Or using Muratic acid instead of hydrochloric.

 

[Boncuk]

I have switched to Sodium Persulfate.

... which behaves nasty on clothing.

 

[Boncuk]

I think we're having language clashes =)

As Unclejed said both names are used for the same chemistry.

 

[3v0]

... which behaves nasty on clothing.

I have not noticed that.