Author Topic: encapsulating board with RTV silicone  (Read 1117 times)

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Offline LaserTazerPhaserTopic starter

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encapsulating board with RTV silicone
« on: May 27, 2019, 09:33:23 pm »
Theres this http://www.chipquik.com/datasheets/NCS10W.pdf large non corrosive RTV and the more expensive non corrosive electronics RTV http://www.chipquik.com/datasheets/EGS10W-20G.pdf

Would the NCS10W damage anything if a board were encapsulated with it? Products appear to be marketing gimmick they both denote nearly identical specifications even datasheets appear nearly identical aside from product image and few minor objects.
« Last Edit: May 27, 2019, 09:47:15 pm by LaserTazerPhaser »
 

Offline wasyoungonce

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Re: encapsulating board with RTV silicone
« Reply #1 on: May 28, 2019, 01:31:28 am »
The NCS10W mentions natural cure (non-acetic)  the EGS10W doesn’t.   But it does look as they are similar.  Hard to tell. 

If potting, you have to ask does it really need it aka: HV; mechanical; moisture.  If it’s that important for any of the above maybe consider using the proper stuff like silguard or proper potting compounds from suppliers.

If it’s for general non specific home stuff, any non-acetic RTV.  The small tubes are good as the stuff doesn’t last. Chipquik would be re-branded.


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Offline floobydust

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Re: encapsulating board with RTV silicone
« Reply #2 on: May 28, 2019, 01:56:59 am »
They both look the same and good for electronics. As long as you don't use acetoxy curing silicones (release acetic acid curing).

You can get more information from the MSDS.
"... This product reacts with water, moisture or humid air to evolve the following compounds: Methyl Ethyl Ketoxime (MEKO)."

 
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Offline LaserTazerPhaserTopic starter

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Re: encapsulating board with RTV silicone
« Reply #3 on: May 28, 2019, 02:08:47 am »
They both look the same and good for electronics. As long as you don't use acetoxy curing silicones (release acetic acid curing).

You can get more information from the MSDS.
"... This product reacts with water, moisture or humid air to evolve the following compounds: Methyl Ethyl Ketoxime (MEKO)."
They both appear to bare identical physical properties found in MSDS. The electronics grade RTV makes MEKO but the non electronics grade RTV doesen't make it. The non electronics grade RTV has more certifications and even the same ASTM C920 certification as does electronic grade RTV silicone.

https://www.chipquik.com/msds/NCS10W.pdf

https://www.chipquik.com/msds/EGS10W-20G.pdf

The only difference they seem to have is electronics grade RTV silicone is UL recognized while the other isnt. They are both non corrosive, aside from corrosion what other issues can non electronics grade RTV cause?
« Last Edit: May 28, 2019, 02:18:03 am by LaserTazerPhaser »
 

Offline floobydust

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Re: encapsulating board with RTV silicone
« Reply #4 on: May 28, 2019, 02:25:26 am »
Some silicones act as an insulator and others as a bit of a heatsink, so parts can run hotter or cooler than expected.
Higher leakage currents but I'm not sure how hygroscopic the product is or if it's in a wet environment. No-clean flux residue and silicone encapsulants are just a mess. Your board should be clean.
Vibration can be a problem with the encapsulant's mass and springyness. Automotive uses either very soft silicone gels or hard potting compounds. Any mechanical resonance can be a disaster for large through-hole parts and wiring.
 
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Offline LaserTazerPhaserTopic starter

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Re: encapsulating board with RTV silicone
« Reply #5 on: May 28, 2019, 02:28:21 am »
Some silicones act as an insulator and others as a bit of a heatsink, so parts can run hotter or cooler than expected.
Higher leakage currents but I'm not sure how hygroscopic the product is or if it's in a wet environment. No-clean flux residue and silicone encapsulants are just a mess. Your board should be clean.
Vibration can be a problem with the encapsulant's mass and springyness. Automotive uses either very soft silicone gels or hard potting compounds. Any mechanical resonance can be a disaster for large through-hole parts and wiring.
Neither RTV silicone mentions thermal properties likely perdue them being identical product with electronics grade being slightly more refined to meet UL criteria.
 

Offline floobydust

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Re: encapsulating board with RTV silicone
« Reply #6 on: May 28, 2019, 04:36:39 am »
You could contact ChipQuik and ask what the differences are. DOW/Henkel have application engineers that can get you past the brochures.
Sometimes the exact same product is marketed for many different (consumer) uses, so people don't think it's general purpose and is specifically tailored and "must be the best".

UL is mainly concerned about flammability and dielectric strength. Silicones pass that pretty easily, but it costs a lot of money to do the tests for an industrial product. You'd need UL approval of the encapsulant for a UL approved product.

I don't see any hardness or Shore numbers, those might be a difference.
MG Chemicals has lots of RTV and potting compounds too, for 1 and 2 part and small batches.
 
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Offline T3sl4co1l

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Re: encapsulating board with RTV silicone
« Reply #7 on: May 28, 2019, 04:47:45 am »
They both look the same and good for electronics. As long as you don't use acetoxy curing silicones (release acetic acid curing).

You can get more information from the MSDS.
"... This product reacts with water, moisture or humid air to evolve the following compounds: Methyl Ethyl Ketoxime (MEKO)."

Or amine curing silicones!  Ammonia is just as corrosive to copper.

That stuff sounds fine though.

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