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What Kind of Silicone Coating is This?

Thread starter #1
Hi,

I have a Dewalt DCS355 oscillating tool (power tool that cuts various materials through vibration) that I have made a repair. I had to take the circuit board out to make the repair and to do that I had to remove a lot of this "potting" type silicone that covered the board. I've looked around a good bit but most of the potting compounds I've seen online aren't silicone. The ones I have seen are usually a two part mixture and I'm not sure if that's what I need or not. Can y'all point me in the right direction of what I need. Attached are some photos.

Thanks
 

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unclejed613

Well-Known Member
#3
digikey search for potting compound

you want to avoid the type of silicone that smells like vinegar (acetic acid) because it will corrode wiring, so don't use the silicone that you can get in a hardware store. the acetic acid is a byproduct of the adhesive polymerizing. make sure the silicone is of the "non-corrosive" variety.
 

dknguyen

Well-Known Member
#5
I thought an epoxy was a hard substance, this stuff is soft and pliable.
I misread your question. Two-part is what you want since, whether silicone or epoxy, when potting anything it's too thick to properly air cure.

I have seen potting before that was slightly soft which also made me question whether it was epoxy or not. I think there are two parts silicones that exist.
 
Thread starter #10

dknguyen

Well-Known Member
#11
Wiki says:
Platinum-based cure system
In a platinum-based silicone cure system, also called an addition system (because the key reaction-building polymer is an "Addition reaction"), two different chemical groups (a silicone hydride and a vinyl) react in the presence of platinum (which serves as the catalyst). In this reaction, an ethyl group [C(H2)- C(H2)] is formed and there are no byproducts. Two separate components must be mixed to catalyze the polymers: one component contains a platinum complex which must be mixed with the second component, a hydride- and a vinyl-functional siloxane polymer, creating an ethyl bridge between the two. Such silicone rubbers cure quickly, though the rate of or even ability to cure is easily inhibited in the presence of elemental tin, sulphur, and many amine compounds.[1]

So it sounds like platinum-cure is not corrosive since there are no byproducts. Never heard of it before though.
 
Thread starter #12
Wiki says:
Platinum-based cure system
In a platinum-based silicone cure system, also called an addition system (because the key reaction-building polymer is an "Addition reaction"), two different chemical groups (a silicone hydride and a vinyl) react in the presence of platinum (which serves as the catalyst). In this reaction, an ethyl group [C(H2)- C(H2)] is formed and there are no byproducts. Two separate components must be mixed to catalyze the polymers: one component contains a platinum complex which must be mixed with the second component, a hydride- and a vinyl-functional siloxane polymer, creating an ethyl bridge between the two. Such silicone rubbers cure quickly, though the rate of or even ability to cure is easily inhibited in the presence of elemental tin, sulphur, and many amine compounds.[1]

So it sounds like platinum-cure is not corrosive since there are no byproducts. Never heard of it before though.
Thanks, I had looked it up briefly, but I never saw where it was corrosive or not. I also looked up MG Chemicals RTV and the prices were much more costly.
 

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