What is epoxy of mylar cap made from?

[Bob J.]

Hi all,

I would like to know what is epoxy of mylar capacitor(red) made from
for molding coil(Litz) and EMI shield(Sheet)?

Thanks,

 

[Ban]

Hi all,

I would like to know what is epoxy of mylar capacitor(red) made from
for molding coil(Litz) and EMI shield(Sheet)?

Thanks,

Can I guess?
It is made of epoxy resin with red paint... apparently. But be careful, the
wires are probably magnetic and will upset your coil and Q-factor.

 

[Bob J.]

Dear Ban,

That is right, I really want to know expoxy resin of mylar capacitor.
Additionally, I will not use the wire of mylar capacitor, but need
epoxy resin.

Thanks,

 

[Ian Stirling]

Dear Ban,

That is right, I really want to know expoxy resin of mylar capacitor.
Additionally, I will not use the wire of mylar capacitor, but need
epoxy resin.

You do know that mylar is one sort of plastic, and epoxy is another?
Mylar is a trademark of Dupont (IIRC), for Poly Ethylene Tetraphalate.
Wikipedia should tell you more.

 

[James Thompson]

Hi all,

I would like to know what is epoxy of mylar capacitor(red) made from
for molding coil(Litz) and EMI shield(Sheet)?

Thanks,

Are you just needing a compound to dip your own wound coils in to encase
them against damage and maintain the coil spacing? Or just curious about
what the epoxy compound is?

 

[Bob J.]

Yes, It is going to be used to mold coil and EMI shield to maintain its
own frequency characteristics. It is secondary part of coreless
transformer for contactless things.

 

[Roy L. Fuchs]

You do know that mylar is one sort of plastic, and epoxy is another?
Mylar is a trademark of Dupont (IIRC), for Poly Ethylene Tetraphalate.
Wikipedia should tell you more.

The mylar is the film used as the dielectric for the cap. The epoxy
ia the encapsulant, and is usually not painted.

A similar epoxy material for the electronics industry that he can
find and buy is called "Stycast".

http://www.emersoncuming.com/docs/proddocs/SGStycastEncapsulants.pdf

It can be made highly thermally conductive as well. Silica powder
added to it works, but they actually sell one already done up. It is
bright blue.

 

[Roy L. Fuchs]

Yes, It is going to be used to mold coil and EMI shield to maintain its
own frequency characteristics. It is secondary part of coreless
transformer for contactless things.

You probably do NOT want a hard epoxy then. It can shear wires from
the thermal expansions. There are transformer encapsulants out there
for the purpose. Things have to have a small degree of flexure.

One is called Dolph's AC 43 impregnation varnish (top of the line).
They are a decades old company that has been doing it for years.

http://www.faet.it/english/ssfam.asp?cod=808&a=Material for windings&b=Dolph's paints

If you are worried about voltage arcing, you should vacuum impregnate
it, or reduced pressure at least. The AC43 has a 2000V per mil
breakdown strength.

It can be baked for faster cure at up to 275 F (135C). That is
usually not too hot for most plastic coil forms.