Cleaning solder flux from a pcb?

Tim-M

Do you guys have a method for cleaning solder flux from a printed circuit board using stuff that may already be around the house?

I just built another OEM BS2 and used Isopropyl Alcohol and a short bristle brush to clean the board up. The flux has been cleaned pretty well, but now that the board has dried it looks chalky and the luster is gone.

I know there are flux removers specifically for this purpose but I don't have any... any ideas that might allow me to finish this yet today or is a flux remover the right way to get it done?

Thanks,

Tim

Velocit

When I can't use the commercial electronics cleaner, I use acetone followed by a rinse in hot water. I then gently shake the board dry and place it under a fan. This method seems to do the trick in most cases.

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-Paul

Whit

The first wash with the alcohol will usually leave it that way (chalky and dull). It is like it just dilutes the flux and leaves a thin film everywhere. If you wash it again, you will probably be o.k. (at least that is my experience).

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Whit+


"We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney

LoopyByteloose

The chalky and dull is not likely to be a film of flux. I clean with alcohol and had similar results.
As you can see, alcohol creates lead and tin oxides. It is acidic and this is the same problem that auto makers have with adding it to gasoline. Using acetone will leave you with a nicer board, but you must make sure plastic components and inks do not dissolve. The best choice is to use a water soluble flux and solid core solder. That flux washes away with plain water rather than the traditional rosin core solder which requires solvents.

You might clean up a chalky dull board with a household spray cleaner normally used for plastics. As long as it is merely soap and doesn't add a coating to the board, it may be exactly what you need. Stay away from products like Armorall until you really want to build up a coating of plastic. That coating may look nice in the beginning, but deteriorate or cause big problems later on.

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It's sunny and warm here. It is always sunny and warm here.... (unless a typhoon blows through).

Tropically, G. Herzog [noparse][[/noparse] 黃鶴 ] in Taiwan

Post Edited (Kramer) : 9/29/2008 3:01:19 AM GMT

Franklin

Be aware that water soluable flux in most cases MUST be rinsed off, it's an acid.

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- Stephen

Leon

I use 99% IPA and don't get any residue. The OP might be using less pure stuff.

Leon

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Phil Pilgrim (PhiPi)

For activated fluxes, I use a toothbrush drenched in 99% isopropyl alchohol. This is the high-test stuff — not rubbing alcohol, which is diluted with water. You can find it at most pharmacies.

DO NOT USE ACETONE!!! (Kramer, what were you thinking???) It will soften the epoxy in the board and lay waste to any other plastics (i.e. connectors, chip packages, etc.) it comes in contact with.

-Phil

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LoopyByteloose

Sorry, but since acetone is safer for people's health than mineral spirits, benzene, toluene, and other aromatic hydrocarbons, it seemed a better choice.

It helps know your materials. It certainly does dissolve vinyl and a variety of plastics, but in most cases somewhat slowly. Cured epoxy seems to take more than average abuse.

I did note that you should check it. Not all printed circuit boards are epoxy. Some are phenyl impregnated paper. I suspect that the acetone won't affect that.

In fact, what ever solvent you are using, you should check before washing plastics. Use a q-tip and try a small unimportant area. Being in Taiwan, I get a lot of weird things for solvent that are labeled in Chinese as simply paint thinner or mineral spirits. Some will instantly turn any plastic to mush and others won't affect most plastics. I never know what I can use without testing.

In the U.S., it has gotten nearly impossible to get toluene or lacquer thinner anymore. In fact, just about any solvent is on an environmental air control list. That is in part why the big manufacturers simply switched to water-based flux. It is cheaper, avoids air pollution regulations, and cleans up with plain water. You can buy a gallon of the stuff very cheaply.

Even alcohol is now regulated in the U.S. for air pollution. Large bakeries must assure the E.P.A that the yeast used in production of bread is not releasing too much into the atmosphere.

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It's sunny and warm here. It is always sunny and warm here.... (unless a typhoon blows through).

Tropically, G. Herzog [noparse][[/noparse] 黃鶴 ] in Taiwan

Tim-M

Thanks for the help and advice everybody!
I didn't go near the acetone as I know what it does to plastics.
I'll be picking up some commercial board cleaner and some 99% isopropyl alcohol.
I had contact cleaner on hand which did a reasonable job of clearing the chalky residue and cleaning the board.

Tim