I am working on restoring an old Intel Motherboard with a 478 PGA Socket, an accompanying Intel Pentium 4 Prescott, and various expansion cards that have some form of dry mold coating it. I am working on cleaning the surface level mold off with electronics grade isopropyl alcohol but the only solution I could think of to ensure the board mold free would be to completely submerge it in the isopropyl alcohol. I know many people that restore retro electronics do clean PCB's that way but I have never actually done that myself. Are there any pitfalls of submerging a board in a cleaning solvent?

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    There are man alike questions ( 2210, 6076, 11022, 1933, 1667, 5318, 6237, 21584), have you read thru the answers given there?
    – Raffzahn
    Commented Apr 10, 2022 at 21:53
  • Yes. I had read some of those answers. My concern is that this motherboard's components are mostly SMD and I do not know if this makes a difference. Commented Apr 10, 2022 at 22:43
  • SMD are soldered like any other component. All parameters, beside the missing pins are the same as before. That's what made them so much more successful than other attempts like hybrid (which still got its niche) . Also, if you're looking for specific information for a certain board, or technology, it would be worthwhile to mention that as part of the question, wouldn't it?
    – Raffzahn
    Commented Apr 10, 2022 at 22:55
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    Voting to leave open. While we have had many circuit board cleaning questions, none of them address mold. That makes this a new question, not a duplicate.
    – DrSheldon
    Commented Apr 11, 2022 at 3:10
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    @DrSheldon Mold doesn't differ from any other dirt. More important, the question is not asking for mold related methods, but if it's safe to submerge (SMD) boards i isopropyl alcohol.
    – Raffzahn
    Commented Apr 11, 2022 at 8:54

1 Answer 1


For what it's worth, on moldy 8-bit machines I've often used a fungicidal product on the Danish market called Rodalon which I think may be more or less equivalent to Lysol, but you can look it up for a break down of the component chemicals.

While IPA has good cleaning properties, I've found that it can still be hard to get rid of the "basement" smell after mold, and the Rodalon solution cures that.

It can be sprayed on but to be most effective I prefer to submerge the PCBs or cases in a solution of destilled water and Rodalon and brush the board carefully, fx with a toothbrush. The caveat is the same as for any kind of deep board washing: it should only be done if there are no components such as relays or other components that could react poorly to or retain water.

Rinse in clean destilled water, blow dry, rinse in IPA to help displace the water, and dry again carefully with warm air, especially around switches, under ICs and other places that could retain water.

  • A good example of something you don't want to get wet that I've run into is the delay lines and bandpass filter on Amiga A600 & A1200 motherboards. Usually it's the nearby surface mount electrolytics leaking into them that kills them, but my understanding is any liquid intrusion can damage them. A lot of people won't notice if they screw them up though since it only effects the composite and RF video outputs.
    – mnem
    Commented Apr 11, 2022 at 13:08
  • IPA = isopropyl alcohol, correct? I initially read that as "India pale ale", which you probably don't want to be using on circuit boards. Commented Apr 12, 2022 at 16:49
  • That would be isopropyl alcohol, a.k.a. isopropanol, yes. (A pale ale on the table during a restoration session never hurt either, but best not to mix these IPAs. :)
    – user6576
    Commented Apr 12, 2022 at 17:14
  • One other caveat: IPA is safe to use on most plastics but not on acrylic which is often used for windows, some light pipes etc. it causes tiny cracks on the surface and clear parts become foggy and brittle.
    – Frog
    Commented Apr 15, 2022 at 7:31

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