What Coating is This?

KDoug · Sep 19, 2018

Hi, I just got done making a repair on my Dewalt DCS355 oscillating tool and am trying to find a similar coating/adhesive that was used.

It kind of has qualities similar to silicone but it's breaks easier if you bend it. I need something similar to this because it is what glues the circuit board down to the case it was in.

Thanks in advance for any help.

KDoug · Sep 19, 2018

Another picture of the flexibility

dknguyen · Sep 19, 2018

There are many different kinds of silicone. Are you sure it's not just the kind of silicone that does not produce acetic acid when it cures and is thus non-corrosive and intended to be used with electronics?

RTV162 and it's expensive because it's meant to hold down components onto the PCB.

RTV1035 might be the kind that's more suited for the purpose you're looking at, and cheaper.

KDoug · Sep 19, 2018

I got to looking on Chemtronics and MG Chemicals, what is a conformal coating?

dknguyen · Sep 19, 2018

Conformal coating is a thin coating used to protect boards from moisture and vibration. It's not intended to adhere anything together.

KDoug · Sep 19, 2018

Ok. There is also a clear silicone like coating that is on the board too. If I made a solder repair job, should I put some more of this coating also?

dknguyen · Sep 19, 2018

That clear silicone coating is the conformal coating. If you repair it you could replace it with more silicone conformal coating. It's up to you and whether you just use your drill indoors ocasionally or on a wet dirty work site.

You should be able to solder through the silicone conformal coating for your repairs (not possible with other types of conformal coating).

KDoug · Sep 19, 2018

dknguyen said:
That clear silicone coating is the conformal coating. If you repair it you could replace it with more silicone conformal coating. It's up to you and whether you just use your drill indoors ocasionally or on a wet dirty work site.

You should be able to solder through the silicone conformal coating for your repairs (not possible with other types of conformal coating).

There is 95% of the conformal coating still on it. I guess I'll just get the adhesive type silicone. So you believe I need an RTV type? I thought that was for higher temperature applications.

dknguyen · Sep 19, 2018

There are many kinds of RTV silicones. You need the kind that produces no acetic acid when it cures so the common stuff won't do.

You DO NOT want acetoxy silicone.

You want neutral cure, non-corrosive, oxime or alkoxy silicone. If it does not advertise it, then it is acetoxy.

KDoug · Sep 19, 2018

dknguyen said:
There are many kinds of RTV silicones. You need the kind that produces no acetic acid when it cures so the common stuff won't do.

You DO NOT want acetoxy silicone.

You want neutral cure, non-corrosive, oxime or alkoxy silicone. If it does not advertise it, then it is acetoxy.

Thanks for your help. I changed my mind after thinking. I'm going to put a conformal coating back on the board since it will be exposed to a lot of dust. What do you recommend, acrylic or silicone, or any other type?

Just another thing I saw...What is a potting compound?

Sorry for the questions, I don't have much electronics background.

dknguyen · Sep 19, 2018

I like silicone.

potting compound is encasing in a block of epoxy hans solo style. very protective, very permanent.

KDoug · Sep 19, 2018

dknguyen said:
I like silicone.

potting compound is encasing in a block of epoxy hans solo style. very protective, very permanent.

Gotcha. I forgot to mention if you don't what an oscillating tool is, it produces a lot of vibrations to cut various materials. So that would be why there was so much silicone to reduce shock.

If the board was covered with silicone, why would they need to put a conformal coating on it?

KDoug · Sep 19, 2018

Here is picture of the softer type silicone that was on the board.

There are three types of coatings:
1. Conformal coating
2. Soft flexible silicone
3. Silicone adhesive on backside

Would you consider the softer silicone a potting compound?

dknguyen · Sep 19, 2018

KDoug said:
Gotcha. I forgot to mention if you don't what an oscillating tool is, it produces a lot of vibrations to cut various materials. So that would be why there was so much silicone to reduce shock.

If the board was covered with silicone, why would they need to put a conformal coating on it?

i imagine the conformal coating was for worksite grime and moisture. The white silicone for vibration and mounting. The coverage for sealing out moisture is quite high and you want no air pockets where moisture be absorbed, migrate to and condense. The white silicone might not be suitably "conforming" to do this.

KDoug said:
Would you consider the softer silicone a potting compound?

no

KeepItSimpleStupid · Sep 19, 2018

Locktite SI 5011 https://www.rshughes.com/p/Loctite-...ite-Superflex-Non-Corrosive-RTV/079340_51387/ ought to work for you.

KDoug · Sep 20, 2018

Would this be sufficient? MG Chemicals has many different RTV adhesives in their website, but I saw this in Amazon.

https://www.amazon.com/MG-Chemicals-1035-80ML-Corrosive-Translucent/dp/B005T8R6LY

dknguyen · Sep 20, 2018

that is the RTV1035 I mentioned earlier

KDoug · Sep 21, 2018

dknguyen said:
that is the RTV1035 I mentioned earlier

I apologize, having trouble keeping up with things. Thanks again for your help.

KDoug · Sep 23, 2018

I was able to find some Momentive RTV 162 for about $12 shipped off EBay.

My next question is what would be a replacement for the soft type "potted" silicone that was originally poured on the board. Remember this tool produces a lot of dust and vibration when in use, so I'm trying to get the most amount of shock protection possible.

Or do I even need the "potted" type silicone if I put a couple heavy coats of silicone conformal coating on the board?

KDoug · Sep 24, 2018

Here is what it should look like:

What Coating is This?

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