Cleaning boards

MG chemicals Flux cleaner and a acid/epoxy brush with the bristles cut down to about 1/2" long. Alcohol will work as well but not quite as good.

If using a water clean flux Alcohol will do a poor job. use a Water based flux cleaner.

You can wrap the acid brush with tape and squirt the flux cleaner down the hollow handle and it will wick out the bristles as you scrub.

no worries about knocking components off. you don't need to scrub that hard. Let hte bristles do the work.

I like acetone and a small brush.

John

Well, in every case, it is 100% dependent on what solder process was used, and what type of flux.

Water soluble? Use HOT water, preferably de-ionized, filtered water.

Only if you have no transformers on it that have not been vacuum impregnated. OR you could bake it for several hours afterward, or subject it to a vacuum for a while to draw out and evaporate any water that remains.

RMA flux, use HOT IPA 99%, then a vacuum chamber session and a bake session as PCB media is hygroscopic, particularly after being stripped clean with alcohol.

No clean?. I would read the spec sheet on it for what the flux is soluble in that does not also attack other component elements.

Acetone on a PCB? You're nuts! It will melt nearly any polymer used on it, including some silk screen inks, and will definitely strip clean any EL cap markings, etc.

Unless you are one of those "women cleaning their nails" types that would sit there with a q-tip swab and clean each solder joint individually.

After that waste of labor and money, you could buy a purpose specific cleaning 'machine' and save time and money. It would pay for itself in short order.

For prototypes made with rosin-flux solder, I use lacquer thinner and a toothbrush- the free ones from the dentist generally work fine for me. Outdoors, or in an area with good ventillation. The lacquer thinner can take some markings off, so avoid contact with e-caps etc. There is commercial flux remover too, but I find the lacquer thinner works well.

Best regards, Spehro Pefhany

Cheap way I use with rosin flux solder is: methylated spirits (a soak for a minute helps) then brush with tooth brush. Brush & rinse with distilled / deionised water. Dry off in the sun or in the oven set to the coolest setting.

Rosin fluxes use an alcohol vehicle. Why would you use paint thinner on that? Not only that, but it attacks other elements of the assembly besides just the flux.

It works better, IME, and dries faster. As with an uncontrolled soldering iron, one must work skillfully to avoid compromising quality.

Best regards, Spehro Pefhany

Any PCB assembly can handle like 80C. for long term baking operations.

That is like 176F.

Yeah that'd be about what our (kitchen) oven does on lowest setting, just hot enough that you can't hold it for too long!

An alcohol wash NEVER compromises anything when used to clean a pcb.

One can even use it on old, crystallized flux, if you first heat up both the assembly, and the alcohol. When you apply the heat to the assembly, you may see it re-liquify, making it even easier to remove.

What "compromise in quality" do you refer to? Unless you are talking about YOUR process.

Safewash (Electrolube product, can be got at Farnell) in a cheapo Chinese ultrasonic cleaner then 3 rinses in de-ionised water then dry with fan heater. Much safer (for you) than orgranic solvents and seems to do a very good job.

Michael Kellett

Exactly. And that you have to let cool for a bit before continuing.

Along with various fluids already mentioned, I use electric toothbrush for scrubbing.

-- Boris

hol?

ue

Likely the best technique, mine is similar. I often get away with a solvent for pain which is mostly acetone and some other aggressive stuff, but it has heavy fractions which are known to be killing in some cases (e.g. Ge detector preamps where almost everything is :-) ). I recently had a related moronic experience - knowing that this solvent can be bad and thinking it finally got me. I had just put together the prototype of a new product (

Dimiter

------------------------------------------------------ Dimiter Popoff Transgalactic Instruments

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IPA tends to leave white residue. For a hand-soldered board, as OP states he's doing, and RMA flux, targeted brushing with a strong solvent like acetone works great. Acid brushes work well. Of course don't use acetone on parts that don't like it.

Water soluble and no-clean fluxes are awful, especially if surface leakage matters.

Production cleaning is a different animal.

John

Every tried Goo Gone? It gets rid of flux just fine and doesn't melt plastics. It seems to evaporate away, although I've always wondered whether or not it's still leaving some thin film behind.

Awful is tens of megs between points, say, 1/8" apart? Or hundreds?

Thanks,

---Joel

ol?

If you use water-soluble flux, mist the board with a low-residue wetting agent (Kodak Photo-Flo in few-drops-to-a-pint dilution). Then, do a distilled or deionized water rinse: use a squeeze-bottle to play a jet of clean solvent, finishing with a top-to-bottom final rinse. A bit of compressed air will help chase the last droplets off, but stand the board on edge, on an absorbent towel, to dry. On some kinds of low-power circuitry, especially in solder-bump, the dry period afterward can take days.

If you're in a hurry, follow the water rinse with isopropyl alcohol.

I think they've done something to that stuff. I keep it around to take off adhesive overspray (I think it leaves a *lot* of oil behind, BTW) but the last bottle I bought smells like soap rather than citrus and doesn't work worth a d*mn.

And what kinda parts are these? Will almost all IC's, passives, LED's, etc be fine with acetone?