EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: 001 on October 05, 2019, 05:38:25 pm
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Hi
Can ultrasonic cleaner destroy electronics? :-//
Can I clean quarz, ceramic tube sokets, carbolite knobs?
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I can't imagine it being the case. Quartz is very similar to glass, I definitely think you are safe there.
I hear that less stabile minerals, and jewellery with pearls can be destroyed, so I would worry about mica disintegrating.
Ceramics should be fine too, I suspect.
--Chris
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Ultrasonic cleaners can damage quartz crystal oscillators etc. if they induce a mechanical resonance that overloads the crystal itself, its support structure or contacts. Low frequency tuning fork crystals are particularly vulnerable. Any part with delicate sprung contacts is liable to damage so you also have to be careful with switches and presets. Also, unsupported bond wires are at risk, which means some semiconductors in un-filled hermetic packages.
However nearly all risk of damage is mitigated if you use an ultrasonic cleaner with a swept frequency drive, as it doesn't stay at any single frequency long enough for a significant mechanical resonance to build up.
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IMUs, accelerometers can be damaged by ultrasonic welding an enclosure the PCB is fastened to. I was told by a manufacturer it is not recommended but might be ok if you are careful.
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Yes ultrasonic cleaners can damage electronics. Don't put parts in a bath for very long or high intensity.
It is abrasive and etches any metal. You will see solder joints look pitted. It also flexes bonding wires in IC's and can break them.
Use IPA+water and dish soap and not for more than a minute, depending how strong your machine is.
Try a test on a small part or pcb to see what happens after a long run.
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You probably want to look up the datasheets of the components.
Some components have stickers on they to cover them for washing the flux off (e.g. piezo). So for some it might even be problematic to be submerged.
Also afaik some datasheets specifically state to no ultrasonic clean them.
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I suspect that your question actually concerns the physical effects of the ultrasonic waves, but even before you get to that stage, you should consider the simple chemical aspects of immersing a PCB. In the past, ultrasonic cleaners often made use of solvents, and in particular, the Freon compounds. But Freons were banned and then there was a strong general push to move away from volatile organic compounds (VOC's), so that now, ultrasonic baths tend to be used with water with a cleaning additive. Additionally, it is often the case that the recommendations are for the bath to be run somewhat above ambient temperatures. So, even without considering the ultra-sound, you now have a nice cocktail for corrosion, especially so when different metals are present which may encourage galvanic corrosion. You'd need to proceed with caution; I've seen some quite weird things go on in ultrasonic baths.
You can use propanol (IPA) as a cleaning agent, though it not particularly effective and it is quite volatile.
As for the effect of the sound waves, I'll leave others to comment.
S
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Chemical corrosion isn't an issue with ultrasonic cleaners assuming appropriate cleaning agents are used.
Cavitation damage can happen but is generally rare. You can further minimize the risk by using a higher frequency instrument, but 40kHz seems to be the industry norm for electronics (100kHz+ for sensitive parts).
Increasing frequency makes cavitation bubbles smaller, leading to less intense implosions.
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Chemical corrosion isn't an issue with ultrasonic cleaners assuming appropriate cleaning agents are used.
Well, that is an extraordinarily broad statement. Of course the key phrase is "assuming appropriate agents are used". Especially when there are a number of different metals present, finding agents which are good cleaners and not at all corrosive may not be easy. Proving conclusively to a demanding customer (e.g. German aerospace engineers) that your process is not harmful, may be harder still.