Author Topic: Parent's Air Purifier  (Read 450 times)

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Offline DDock

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Parent's Air Purifier
« on: November 18, 2017, 08:34:14 pm »
I would consider myself a newbie/moderate still when it comes to electronics repair. My parents tasked me with figuring out what is wrong with their Ionic type air cleaner. I know what the issue is, but I think it is going to occur elsewhere because it looks like the copper in the PCB is corroding like rust. Any idea how to clean it to stop the decay of the traces? I have attached images. I am going to run a modwire from the button because the trace has completely decayed away.

 

Offline Ian.M

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Re: Parent's Air Purifier
« Reply #1 on: November 18, 2017, 10:16:00 pm »
Most commercial PCB etching uses the Acid Cuprous Chloride process, because the etchant can be cheaply regenerated and the copper recovered, minimising chemical waste production.   Unfortunately copper is very seriously affected by chloride corrosion, and once pitting occurs its very difficult to remove or deactivate the chloride ions, so if the PCB was insufficiently rinsed during production, there can be a chemical time-bomb lurking under the solder mask.   

See https://en.wikipedia.org/wiki/Bronze_disease   

Treating the corrosion is almost certainly uneconomic. You'd have to strip all the soldermask and possibly remove the components as well.
 
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Offline DDock

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Re: Parent's Air Purifier
« Reply #2 on: November 19, 2017, 03:59:35 am »
Thank you for your insight. I ended up just mod wiring all the traces I saw with the corrosion to be on the safe side. It is working again, my parent's will be happy for awhile. I will have to tell them that it may stop working again if the corrosion spreads.
 


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