Where Can I Find Ferrite-Impregnated Silicone or Epoxy for RF Noise Suppression?

[fizz_it]

I have a PCB inside of a consumer product that our company does not make. It is emitting a great deal of RF noise in the 350MHz band. I am looking to find a silicone or epoxy with ferrite impregnated in it.

Where can I get it?

I won't be able to get the company that makes the board to change the design in the near future, they are too big and too slow to respond. I have reverse engineered the board and constructed a schematic. I have exhaustively tried various decoupling methods to kill the noise but have not found a solution that is suitable.

Thanks

 

[negitron]

You don't need ferrite, you need an electrically conductive material. Ferrite is great for magnetic shielding, but is terrible for RF EMI. Try something like this:

http://www.mgchemicals.com/products/841.html?PHPSESSID=d41c883dc3548ebc1362bc3c166c5db7

Be sure you ground all of the indvidual coated parts to the supply ground either with wires or spring-loaded grounding fingers.

 

[fizz_it]

Ferrite is used for their RF lossy energy absorbing properties.

Check out - I didn't have to go very for for a good explanation
https://www.physicsforums.com/showthread.php?t=183148

If I put the EMI shielding on the board it will
1 - require that I connect it to ground
2 - short everything that I pour it on

I know, I know, I can put silicone on and then paint the silicone with the EMI shielding. I fact, I have a can of it right next to me, I'll try it out

But I still would like a source for ferrite silicone or ferrite powder

 

[MATLABdude]

Ferrite is used for their RF lossy energy absorbing properties.

Check out - I didn't have to go very for for a good explanation
https://www.physicsforums.com/showthread.php?t=183148

If I put the EMI shielding on the board it will
1 - require that I connect it to ground
2 - short everything that I pour it on

I know, I know, I can put silicone on and then paint the silicone with the EMI shielding. I fact, I have a can of it right next to me, I'll try it out

But I still would like a source for ferrite silicone or ferrite powder

No, ferrite beads are meant to keep long cables from acting like antenna and radiating the RF noise. In a way, it's meant to plug the RF leaks (from the cables coming out of your shielded enclosure). The stuff Negitron linked to is meant to coat the inside of a plastic enclosure, thus leaving enough metal that there's RF suppression due to skin-depth effects. Or you could just use a metal enclosure.