getting rid of gold on pcb

I got curious and found a few net references that it's recommended to remove gold (ex: rings) before going in swimming pools.. " Remove gold jewelry before entering swimming pools. The chlorine in the water will erode gold jewelry."

Well..whatdayaknow... D from BC

Erase it:

Good Luck! Rich

How about Aqua Regia?

Thanks, Rich

Brasso. ;-)

But I don't know if I'd try to _remove_ metal with it - if there's any abrasive in it at all, it would have to be very, very fine.

Cheers! Rich

This is getting funny. I can make you take any position, no matter how absurd. If I say "cars have engines" you'll reflexively deny it. Eeyore does that, too, but not nearly so well.

I can have a lot of fun with this.

John

That's item #6 on my list.. HCL and HNO3 3:1 ratio which is called Aqua Regia..

D from BC

I suppose it's a bit coarser tha jewllers rouge, I've used Brasso to clean scrathes on polycarbonate/ perpsex windows for 16*2 LCDs, takes some time, these day's I would use teethpaste and an electric teethbrusher

Martin

Since gold is softer than copper.. Maybe a copper powder can be used as an abrasive to remove the gold. Guessing.. Copper powder + paint thinner?? Maybe the paint thinner can act like a lapping lubricant. (Brasso has some sort of hydrocarbon..just by the smell.) I picked paint thinner because it's oily, evaporates, easy to get and it's cheap.

Copper powder + graphite ???

Ewwww...conductive abrasives on pcb's...but anywayzz...

Copper wool (found in grocery stores) is harder than gold but as hard as copper (1) so it might qualify as a lapping pad material.

(1) Is PCB copper tempered?

D from BC

What else would aqua regia disolve? BTW in WW2 one nobel prize winner dissolved his medal in AR to stop the nazis getting it. The gold was recovered after the war are re-cast into the medal, neat.

Martin

Maybe stick a bunch of those erasers on an orbital sander for more production :P

D from BC

Toothpaste Toothbrush

It's called solder wick. You add solder, then wick it off. Twice.

That is the mil spec method.

Copper "work hardens". It is notorious for not keeping the crystal lattice it is created with, so heat, flexure, etc. etc. fractures said lattice with great ease, making it as porous as a sponge.

Lets call the whole thing off (song reference to potatoe)

Martin

You guys are all big dopes!

Thanks, it's good to be appreciated, an interesting link , but as Linus said "Intelligence is the ability to avoid doing work, yet getting the work done."

Martin

Hey..those things are for only 1 tooth. :) Teethbrushes are more rugged since it's designed to do more than 1 tooth. :)

Same goes for

Hairsbrush Eyesglasses Earsmuffs etc.. Superior products that can do more than one hair, one eye or one ear.. :P

D from BC

Gold is one of the least reactive metals. The classic reactant is aqua regia. I doubt that a bit of chlorine in water would have much effect. And anything that eats through gold will go wild when it hits the copper.

"When Germany invaded Denmark in World War II, the Hungarian chemist George de Hevesy dissolved the gold Nobel Prizes of Max von Laue and James Franck into aqua regia to prevent the Nazis from stealing them. He placed the resulting solution on a shelf in his laboratory at the Niels Bohr Institute. It was subsequently ignored by the Nazis who thought the jar?one of perhaps hundreds on the shelving?contained common chemicals. After the war, de Hevesy returned to find the solution undisturbed and precipitated the gold out of the acid. The gold was returned to the Royal Swedish Academy of Sciences and the Nobel Foundation presented new medals to Laue and Franck."

John

My Bruning electric eraser would certainly take off the gold, but it would take a long time to do a whole board. It is handy for polishing bare-copper prototype boards or electrical contacts.

John

Gold is only second to Platinum where oxidation effects come in.

Both could stand a hundred years at ambient and not tarnish one iota.

They are more than a little immune to chemical attack as well.

Soldering involves heat. Dissolution of these metals during soldering would not occur were it not for the heat involved. This is why one should always solder with as low a temp process as can possibly be tolerated while still achieving proper wetting, and good micro-crystalline solder joint structure. High heat increases intermetallic contamination in ALL cases.