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Autoclave corrosion coating for BLDC stator/PCB

Autoclave corrosion coating for BLDC stator/PCB

Autoclave corrosion coating for BLDC stator/PCB

Need some help with a coating to protect the iron of a BLDC stator and PCB boards. I've been getting issues with small BLDC motors with rust and electrical issues (open/shorts) on the stator and PCB hall sensors that are caused by autoclaving the motor. The motor is placed in 10 minute autoclave steam cycles (134°C). Things I have tried are nail polish, silicone based conformal coating, and high temp petroleum jelly. They all work a bit just want something better. Potting 2 part epoxy re-sin will work but I like something that I can brush on the stator and PCB components in room temperature.

Any help would be greatly appreciated.

RE: Autoclave corrosion coating for BLDC stator/PCB

Do not use a steam autoclave on these parts! They will get soaked in water and probably not even get fully up to temperature and dried-out in 10 minutes. An air circulating oven will get these parts to temperature, but will likely need more than 10 minutes. I assume you are doing this to sterilize the parts. If you feel you must use a steam autoclave to comply with some FDA regulation or other established procedure, then preheat the parts in an oven before autoclaving. This will prevent condensation inside your motor.

RE: Autoclave corrosion coating for BLDC stator/PCB

What Cpro said. Also, from experience, there is no brush-on conformal coating that will seal out moisture vapor. Even 2-part epoxies will give you conniptions. You need to find somebody who can do parylene coating for you, and then talk to them to figure out your best options.

RE: Autoclave corrosion coating for BLDC stator/PCB

EST, listen to both of these guys, I have been in a similar situation.
Parylene and preheat combined are your only hope, and add a dry out cycle on the end.

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P.E. Metallurgy, Plymouth Tube

RE: Autoclave corrosion coating for BLDC stator/PCB

I was afraid of that, what would be the best option for a 1 part room temperature solution for this (ie. silicone conformal coating, RTV, nail polish....)? I just need something that I can apply myself easily that will survive the most autoclave possible.


RE: Autoclave corrosion coating for BLDC stator/PCB

If you do it yourself a single cycle is probably all that you can rely on.
You need something that is thin, warm you parts, soak and pull a vacuum, then drain and cure.
Silcones are good for temp but not so good with water.
Pay for Parylene, it works.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

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