How can I safely clean baked on polymerized grease from a PCB and components?

[ktmtek]

I'm refurbishing a commercial convection oven, and the pcbs have some grease really baked on. My first hunch is an ultrasonic cleaner, but unfortunately that's not a viable option. I've tried my typical go-to solutions:
-toothbrush
-cue tips
-a few other plastic bristled brushes
-100% isopropyl alcohol
-acetone
-electrical contact cleaner
To no avail. I considered possibly soaking the pcb in acetone or alcohol, but decided not to because I'm worried that may delaminate or somehow damage the pcb. I have a reflow table w/infra-red lamp and considered this as well, but this also poses it's own challenge. I'm afraid that heating it up will only serve to smear and spread the grease. I have a variety of automotive cleaning solvents such as carb cleaner, brake cleaner, engine degreaser, etc etc, but have never tried to use any of them on electronics. Do you think that 1 of those cleaners may work? If so, what should I look for, and are there any chemicals that I need to be aware of that I should avoid? Any tips, suggestions, or advice is greatly appreciated.

[amyk]

What chemicals are in those solvents? They'll usually be hydrocarbons or chlorocarbons, both will be able to dissolve grease relatively well, but chlorocarbons have a higher risk of damaging plastics.

I would try a small amount of regular gasoline to see if that will dissolve the grease. I don't recommend soaking the whole board but applying to individual areas and scrubbing.

[blauerscharik]

If it's grease warm soapy water maybe?

[jpanhalt]

Use a water-based flux remover with "saponifier."  I would use ZEP Heavy Duty floor stripper diluted 1 part ZEP with 2 parts distilled or DI water in an ultrasonic.  Then rinse and ultrasonic (2 min) in distilled or DI water.  Remove and dry.  The key ingredient is alkalinized butyl cellosolve.  If you look at SDS/MSDS sheets you will find cellosolves (often butyl cellosolve) used in lots of heavy duty water based cleaners.  II would not suggest trisodium phosphate (TSP) or its  non-phosphate silicate replacements as they are quite alkaline.

[AndyBeez]

From the photos, it looks like you are trying to attack solid carbon deposits - which are insoluble. You might have better luck with Hydrogen Peroxide, although obtaining H2O2 might be problematic. I think a sonic bath might be the only chemically safe alternative.

[coppercone2]

that board looks like a joke I think I would just desolder parts one by 1 and scrub them if the ultrasonic did not work

figuring out how to clean that POS is probobly gonna take you more time then saving up for a desoldering gun, removing everything, scrubbing it, soldering it back into place then then cleaning the flux off.

or just buy all the chips and replace them. not that bad if you work infront of digikey with good lights. Oven p robobly has generic BS in it you are not gonna have RF asics and custom inductors etc. I see you have the USA flag on your account so just do the american thing with this one!

[Haenk]

Hot steam?

I guess I would consider tossing out this PCB, even asking someone to work on it is an insult IMHO...

[bill_c]

"carb cleaner" and "brake cleaner" will vary from brand to brand, some may be safe, some may strip all mask and silkscreen, some may clean, others may not. Same for "oven cleaner" which may or may not cause corrosion (now and later). Those electrolytic caps have rubber seals on the bottom an may not survive cleaning.
Those boards are not really that bad.