Cleaning the "grunge" off of circuit boards..

[scorch56]

I've had this NES top loader for 3 or 4 years now. It looks good and runs OK, and all.. but I never had it open. It had what sounded like a tiny piece of plastic rattling around in it and it drove me crazy. So the other day I purchased some security bits and opened it up. Well the rattling turned out to be the tooth of a comb (go figure) so I extricated it and noticed how dirty and corroded the board was.

The board is still solid and all.. but much of the stainless steel RF guards and the metal on the pin connector looks like it has "galvanized"; is the best way to put it I guess. It's no longer shiny and mirrorlike. What kind of metal did these guys use on this circuit board anyway? I haven't removed it from the bottom case half yet and looked at the underside yet (where most of the traces would be), but I don't see any copper anywhere on the top. It looks like tin or nickel. I asked my friend about cleaning this.. I was thinking emory cloth and he said no way.. still too abrasive, and suggested super-fine steel wool. I'll try that. But that's not my question.

Now there's a whole lot of dirt, grime, grease and lint on the board itself and in between components. It's too cramped, and looks to delicate for me to get in there and try and clean by hand with my usual "alcohol wipes". Anybody have any recommendations? I was thinking some kind of spray electrical cleaner like "contact cleaner" or such. Or is that too harsh for this kind of thing? The thing is I obviously want to be as gentle as possible without having to actually brush or scrub the board so I'm thinking some kind of spray/aerosol cleaner that runs off or evaporates completely is called for. On a side note.. I have some 99% isopropyl (potent stuff) and I ended up using it to clean some grease, smoke film and even light rust off my mom's brass-plated kitchen light fixture last night and it worked like a charm and didn't harm the finish. Is this stuff too strong for delicate circuitry and traces?

Many, many moons ago when I was married and living in Seattle I worked in a place that built these big control boxes for low-torque/speed motors that drove massive tonnage loads like radio telescopes and such. We built the boxes from scratch and in many cases.. even designed and assembled much of the circuitry, and boards that went in them.

I remember there was this "tank" that we would take newly assembled and dirty repaired boards to clean them in. This tank was about the size and looked.. like the old top reach-in Coke coolers that sat outside gas stations WAY before most of you were born. In the bottom of the tank was a liquid that had solvent qualities (and smell). It had to be kept cool hence the coolertank which had an open top. The liquid would evaporate off into a gas or cloud that would sit in the tank and didn't creep out over the edges. You'd put on gloves (or not.. if you were daring) and put the board down into the tank and pick up a wand that lightly sprayed the board with a fine mist of the liquid. I want to say this stuff was Acetone.. but I seem to remember an inert gas like one of the "-eons" involved. Anyway.. it was colder than shit and the stuff would clean circuit boards like no tomorrow (even ate away "rosin" from new soldering) yet be gentle on the board and components. Can't remember what that stuff was.. but I'm rambling again..

[Bratwurst]

I have not yet encountered a form of grime that isopropyl alcohol and an acid brush couldn't counter. You won't be damaging any circuit board with an acid brush and the bristles are coarse enough to bust up the dirt.

The tank of liquid you're remembering was probably methyl ethyl ketone, amazingly toxic stuff. Just about everyone used it up until the 80s, I heard stories of people dipping the boards into barrels with their bare hands- it goes right through your skin and into your liver, nervous system and brain. Evaporates quite easily- but cleans like nothing else. I have a bottle reserved for the removal of conformal coating, and I use it rather judiciously.

[scorch56]

I have not yet encountered a form of grime that isopropyl alcohol and an acid brush couldn't counter. You won't be damaging any circuit board with an acid brush and the bristles are coarse enough to bust up the dirt.

The tank of liquid you're remembering was probably methyl ethyl ketone, amazingly toxic stuff. Just about everyone used it up until the 80s, I heard stories of people dipping the boards into barrels with their bare hands- it goes right through your skin and into your liver, nervous system and brain. Evaporates quite easily- but cleans like nothing else. I have a bottle reserved for the removal of conformal coating, and I use it rather judiciously.

"Methyl ethyl ketone is a sulfating agent. It gives rise to.." Oops.. memories of Blade Runner for a moment. Man.. if I had a dollar for every banned chemical I was around in my younger days (pre-OSHA). I'm gonna' die of industrial disease someday.

What's an "acid" brush?

[Bratwurst]

What's an "acid" brush?

LINK

They're fairly simple, hollow metal tube, horse hair or nylon bristles, typically used for acid washing a PCB for etching circuit traces. I trim the bristles short on a new brush to make them extra stiff so it busts up dirt better.

[Tron2005]

For the last 7 years i was working for a Circuit board Manufacturing plant and there we used an Acid brush or most soft bristle brushs they wont harm the Circuit board or the parts. use Alcohol and you can get it pretty clean just be careful what you use to wipe it down with because normal paper towels or towels etc have static electricity and they can zap the more sensitive components. and of course make sure the board is completely dry before powering it back up as for the metal RF shielding its just sheet metal so its up to you!

We didnt use that nasty cleaner stuff that was being talked about we used another smelly cleaner and a large can you say a large automated dishwasher (for laymans terms) and a chemical called Vigon. the machine would wash the board completely and some times wash the serial number label or even the ink of the serial number off and dry it in ~10 mins or so