Electronics > Repair
Ultrasonic cleaner size: 10L vs 6L
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CaptainBucko:

--- Quote from: SolderOcelot on July 08, 2024, 03:42:09 pm ---
* Fill it with Distilled water / IPA @ 6:1 ratio
--- End quote ---

Try using a proper PCB cleaner, not IPA + Water Mix. Depending on your country there will be various suppliers. I find the PCB cleaning solutions much more effective and removal of contamination, so you don't need to spend so much time with the item in the ultrasonic cleaner.
SteveThackery:

--- Quote from: MathWizard on July 10, 2024, 01:10:30 am ---So what happens if you don't degas ? Do bubbles just stick to the PCB and not get cleaned as good ?

--- End quote ---

Truth be told, I haven't noticed any difference. Also, I've observed that no matter how long you degas, you still get bubbles forming and rising to the top.  Or at least, that's what I've found with mine.

Perhaps its importance depends on the particular fluid you are using.
SolderOcelot:

--- Quote from: MathWizard on July 10, 2024, 01:10:30 am ---So what happens if you don't degas ? Do bubbles just stick to the PCB and not get cleaned as good ?

--- End quote ---
More bubbles = more risk of damage. Look up "aluminum foil in ultrasonic cleaner test".


--- Quote from: CaptainBucko on July 10, 2024, 04:19:40 am ---Try using a proper PCB cleaner, not IPA + Water Mix. Depending on your country there will be various suppliers. I find the PCB cleaning solutions much more effective and removal of contamination, so you don't need to spend so much time with the item in the ultrasonic cleaner.

--- End quote ---
I wonder what it is about these solutions and why I wouldn't be able to make it myself. So far I've understood these are the essentials:

* Carrier (distilled water)
* Solvent (IPA or something else)
* Surfectant (dish soap)
SteveThackery:

--- Quote from: SolderOcelot on July 10, 2024, 10:08:19 am ---More bubbles = more risk of damage. Look up "aluminum foil in ultrasonic cleaner test".

--- End quote ---

I'm not sure that follows. There is a mechanical cleaning action with an ultrasonic cleaner, and any mechanical action can lead to damage. You manage this by keeping the cleaning time as short as possible commensurate with getting a successful clean. Also, and perhaps obviously, the higher the ultrasonic power density in the fluid, the greater the risk of damage.

I don't see how either of these relate to the visible bubbles.  In fact, the proposed relationship seems to be the other way round.  That is, degassing to reduce the bubbles increases the cleaning action.  So it would seem that the bubbles themselves actually reduce the mechanical cleaning action (by absorbing the shockwaves because the bubbles are "springy") and thus the risk of damage.

Only if the bubbles are used as an indicator of the power density could you say that more bubbles = more risk of damage.  That's why I think the opposite to SolderOcelot: insufficient degassing reduces the cleaning action and the risk of damage.

(PS:) You can't have a mechanical cleaning action with no risk of damage. The fun you can have perforating aluminium foil is simply a demonstration of that fact.  You can also use it as a crude indicator for how powerful the shockwaves are.  That is all.  Degassing the fluid increases the shockwave power, thus also the cleaning action and the risk of damage.
tooki:

--- Quote from: SolderOcelot on July 10, 2024, 10:08:19 am ---I wonder what it is about these solutions and why I wouldn't be able to make it myself. So far I've understood these are the essentials:

* Carrier (distilled water)
* Solvent (IPA or something else)
* Surfectant (dish soap)
--- End quote ---
Commercial PCB cleaners/flux removers for ultrasonic are aqueous, i.e. not solvent-based. The key ingredient is a saponifier (lye or similar), plus surfactants (probably something closer to what’s in all-purpose spray cleaner like Cilit Bang), plus corrosion inhibitors and probably redeposition inhibitors. These cleaners don’t rely on solvents to dissolve the flux, they use the saponifier to make the flux water-soluble.

(Solvent-based cleaners that can be used in ultrasonic do exist, but they don’t contain water. At least I’ve never seen one that does.)

Edit: I’m not so sure now. One aqueous cleaner (Safewash Super, SWAS) does contain various alcohols, but they aren’t normal alcohols (isopropyl, ethanol, etc) and I don’t know enough about chemistry to understand whether the alcohols used are actually “solvents” in the usual sense or not.
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