Etching PCBs with saltwater and a wall wart

[John Lyons]

So I tried out the saltwater etch thing today with a test strip board and a sharpie squiggle drawn on.

Quick rundown for those who are unfamiliar. 12vdc supply negative connected to a copper strip/coil/chunk submerged in water and salt mixture (7% roughly..dissolve as much as you can in enough water to hold your board, the salt will stop disolving when you have added enough)

I used a 12vdc 500ma wal wart and a 12v dome light for a car run in series with the + lead.
I used some 10 gauge solid copper wire coiled up and at the bottom of a quart plastic container and then connected to the - lead.

The etch started working ok but took a long time. Once the copper got thin enough to be almost clear the etch stopped.
Since the particles were so far apart the electrical conduction stopped.

So here's my question for those who have used this method.
How you you etch a standard sized board without connecting all the traces and then cutting them afterwards? Since the etching process will only work with all the copper traces and back ground touching it does not seem that this method will be any easier than the usuall suspects Is it possible?
Seems like a few people have tried this here and there was no mention of it.


John

[birt]

you do need to keep bridges between the traces. if uyou make these in a special color it's easier to find em back after etching

this method works but isn't the easiest to etch pcb's. for enclosures it's ok.

[John Lyons]

Yeah, I tried a few different test strips and they came out crappy, the methods we alreadty use are a lot easier and faster.
For anything solid metal where you aren't getting rid of whole sections of metal (PCBs) it works ok.

Having to keep connected traces make the saltwater etching process not usable. It's a lot more work to remove all the traces afterwards. And even moderate builds... forget it.

Darn...I was thinking this would be so nice to get rid of the harsh chemical elements of etching....

John

[rockgardenlove]

Yep, it doesn't realy work on PCBs as as it takes off the copper you can't get the voltage to the whole board.
I'm happy with FeCl and sodium persulfate

[birt]

Yeah, I tried a few different test strips and they came out crappy, the methods we alreadty use are a lot easier and faster.
For anything solid metal where you aren't getting rid of whole sections of metal (PCBs) it works ok.

Having to keep connected traces make the saltwater etching process not usable. It's a lot more work to remove all the traces afterwards. And even moderate builds... forget it.

Darn...I was thinking this would be so nice to get rid of the harsh chemical elements of etching....

John

i found out that what's left after the saltwater etching isn't a whole lot less toxic than with other etching methods..

[John Lyons]

Do you know what is toxic about the saltwater waste?
The byproduct while etching is hydrogen as far as I know. (the visible fumes that are emitted)

John

[birt]

it's what's left in the water. the salt makes some kind of chloride and toxic stuff with the copper. i'm not into chemics and i forgot what it exactly was. i'll see if i can look it up for you.

i remember that if you use copper sulphate instead of salt that the copper will just go to the copper wire at the bottom so that should be better

[rockgardenlove]

Do you know what is toxic about the saltwater waste?
The byproduct while etching is hydrogen as far as I know. (the visible fumes that are emitted)

John

I don't think it's toxic, or if it is not very much so.
I tasted some.  Was that a bad idea?  Lol.

[black mariah]

Do you know what is toxic about the saltwater waste?
The byproduct while etching is hydrogen as far as I know. (the visible fumes that are emitted)

John

I don't think it's toxic, or if it is not very much so.
I tasted some.  Was that a bad idea?  Lol.

So you tasted the byproduct of an electrochemical reaction... WHY exactly? 

[John Lyons]

Ah it's fine...actually it's very healthy. I pour it over my corn flakes every morning.

Just kidding...my god son... tasted it!!!!!!!!!

[rockgardenlove]

I put in salt, water, and some copper.
Chlorine and hydrogen gas was let off...
Figured it would be ok...looked pretty gross though and it was damn salty.
Yep, I'm nuts.

[Nasse]

Some time ago, maybe year or two ago I saw a diy link, somebody was etching something with similar arrangement, they etched sheet metal into pieces, I thought it could work for cutting shapes out of thick aluminium, maybe logos or letters and such

I lost the link anyway...