Cleaning Circuit Boards

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bigspider
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Cleaning Circuit Boards

Post by bigspider »

I got a Minibrute at a garage sale and it's a lot of fun. I opened the enclosure while I was cleaning it and noticed that there is some sort of residue built up on the circuit board. A lot of people store their electronics in barns where I live, to my lament. I wanted to check that it is safe to go over the circuit board with a toothbrush and some isopropyl alcohol.
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Re: Cleaning Circuit Boards

Post by crochambeau »

A lot of residue we see is factory. There are flux formulations that are "no clean", which will leave a film that tends to discolor in time.

Generally speaking, it is okay to re-clean a circuit board that has residue - though in most instances the cleaning is not required.

I find isopropyl alcohol is decent at breaking things down a bit, but tends to leave film as it evaporates before delivering the material off of the surface of the PCB. The result is a lot like cleaning a window with a greasy cloth.

If you're after a spanking clean circuit board, you can also utilize distilled water, which will flow off materials kicked up by the brush. You want to insure that any back-up battery or other voltage source is removed, and that the PCB is ABSOLUTELY DRY before power is applied. Care also needs to be taken where moving parts are, such as potentiometers or switches. Especially in the case of potentiometers, a suitable lubricant is required for longevity in any instance where original lubricant has been flushed. To further complicate things, different potentiometer types (carbon track vs conductive plastic, etc.) require different types of cleaning solutions and lubrication - and using the wrong stuff can reduce lifespan substantially.

All of this culminates in the notion that cleaning a dirty PCB is often not worth it, and we can comfortably rest on the old addage of "if it ain't broke, don't fix it".

But, TL;DR: yeah, you're generally safe using iso and a toothbrush so long as you steer clear of problem areas and are not after a show-room finish.
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Re: Cleaning Circuit Boards

Post by crochambeau »

It does raise the question of what type of residue you are seeing, in the event you're looking at galvanic reaction from a battery or some such, then absolutely yes clean that shit and address the underlying issue before it spirals out of control and makes repair exponentially more difficult.
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Re: Cleaning Circuit Boards

Post by Indeterminacy »

crochambeau wrote: Sat Jul 24, 2021 10:49 am It does raise the question of what type of residue you are seeing, in the event you're looking at galvanic reaction from a battery or some such, then absolutely yes clean that shit and address the underlying issue before it spirals out of control and makes repair exponentially more difficult.
A big yes.


Straight 91% isopropyl for cleaning, then cut with distilled water in a squirt bottle because it makes a nice second stage rinse, then follow with straight distilled as a final. Mark the bottles well.
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Re: Cleaning Circuit Boards

Post by bigspider »

Thank you for the response. If I do clean the PCB, I think I will use distilled water. I'll have to open it again and see if it is really worth it. I don't think the circuit is at risk of damage.
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Re: Cleaning Circuit Boards

Post by NoiseWiki »

bigspider wrote: Sat Jul 24, 2021 6:52 pm Thank you for the response. If I do clean the PCB, I think I will use distilled water. I'll have to open it again and see if it is really worth it. I don't think the circuit is at risk of damage.
Frankly I wouldn't bother unless it was actually causing issues with the board. But before you commit to cleaning the entire surface just try a small area first to see how easy it comes off or not.
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