painted traces

[gtrboy]

what if you painted the connections under a turret board with conductive ink? expensive, yes but what if you made conductive ink with aluminum radiator stop leak and some adheasive?? what adheasive could be used?

[R.G.]

People have been trying to do additive printed circuit boards since at least the late 50's. The problem is that no conductive gook you can print or paint is either as (a) conductive as copper and (b) as adherent as copper.

Conductive paints are usually dispersions of metal powder in a binder. I've seen aluminum, copper, and silver (!) things like this. They will do fine for gate leads where there is essentially no current flow, but they will fail miserably for traces which have to conduct any substantial current, like heater, B+ or ground leads, and will also have big problems where you want a low voltage drop across a "wire", like with ground references.

But don't let me dissuade you. Give it a try.

[Just Bob]

Unfortunately, aluminum will not work. Aluminuim easily forms a nonconductive oxide that keeps the particles from conducting well. The conductivity of the base metal is OK if you could get them in proper contact. Mixing them with adhesive is a trick. Need enough glue to stick them, but not enough to keep the particles from making contact. Then there's the problem with galvanic corrosion and aluminum. And, aluminum is difficult to solder. People have been working on this ever since electricity was invented.

People do make boards with conductive inks. Some keyboards are made this way. The inks I've used were silver or graphite. You can't solder to them. The conductivity isn't great. They're expensive and don't have a long shelf life. You can use conductive ink as a seed and plate solid metal on top. That's been done successfully. Very messy. Thick-film inks work well if you have a ceramic substrate. They're fired onto the board at 1000 degrees. No simple answers here.