silver ink pen as etch resist

[GGBB]

Well I just did a quick test.  I put a short line of silver ink across an area of my board that was already covered with toner and then etched using the sponge technique.  The silver ink came out completely unscathed.

[greaser_au]

COOL!!!    what brand is this thing?

just for interest I'd suggest your next test is the corrosion resistance of the inked copper,  don't remove the ink for a week or two and then see how  well the copper  solders (use solvent rather than abrasive to remove the ink) , and  maybe even try just soldering through the ink!  

davidt

[R.G.]

Congratulations for just having reinvented "printing a circuit board": paint some coppertraces onto an isolating board, and you won`t have to etch at all!

I wish. My long list of re-inventions doesn't include this one. There was a time back in the ?1950s? when this was tried, with trivial success, but only long enough to realize it was not all that good. The material was copper-bearing paint, with enough copper to make connections. It may even have been tried with silver bearing paint for/by the military. One problem is that the connections have to be printed to the components. Solder is out, for obvious reasons.

It's been re-invented again with metal-bearing epoxies, and more recently I saw a calculator with the keyboard matrix printed in what was probably a carbon-bearing ink/paint. The real problem with actual circuit printing is the connections. Solder is really, really good for electrical connections and service.  In early work on Josephson junctions, they used boards with little pots of mercury as connections. At room temperature, you insert/remove the parts when you want. To make the circuits work, you dunk them in liquified gasses and the mercury freezes.

[mistahead]

I love bringing this back into the mix so to speak.

Go check out the art shops and the local paint section of your hardware store - there are metallic pigment "paints" (copper and iron for starters) that conduct very well, they should also have an oxidizer near them on the shelf as they are usually used to paint teracotta pots or whatnot with the metal, then apply the oxidizer and rinse when its "red" or "green" or "blue" enough (based on the ox and the paint).

They're unsuitable in their "out of the pot" state for ink jet heads so I have a little bit more to go before the wheel is reinvented - but I'm working on it for the sake of doing something semi-novel.

[amptramp]

If you are looking for conductive paint, rear window defroster repair paint is silver-based paint that is used to paint on glass.  It is pricey, but you get silver, which is a good mojo material.  If you could drill the holes, silver conductors on a glass board would look cool and be easy to troubleshoot since you could see where the components are from both sides of the board.