Bluetooth signals and potting compound

[DSGarcia]

If I were to encapsulate a Bluetooth module in potting compund (no more than 1/2" deep), would it still transmit & receive?

 

[Speakerguy]

Do you know the manufacturer/number of the compound?

 

[DSGarcia]

I was thinking of this: https://www.mgchemicals.com/products/832tc.html but after another look (it has aluminum oxide) perhaps this would be better: https://www.mgchemicals.com/products/832b.html. I was looking at the first to discipate heat from the voltage regulators.

 

[Speakerguy]

My only experience with potting compound is that a) it can sometimes be hard to cut through to while cross-sectioning a device (I think that's part of the point for some manufacturers though) and b) the potting compound used in shielded inductors to secure the shield around them lets flux leak out in EMI scans.

That's about all I really know though. I was hoping the datasheets might make mention of it, but all I can see from some of the mfg's I went to was reference to dielectric qualities.

 

[DSGarcia]

My application is to weather-proof the device and for shock/vibration protection. There are a lot of reasons why I can't just use a small waterproof box so potting is my best option.

 

[Centretek]

No potting mix will dissipate heat, in fact all of them insulate because they are poor conductors of heat. You can however fit strip heat sinks that extend outside the potting compound.

 

[DSGarcia]

No potting mix will dissipate heat, in fact all of them insulate because they are poor conductors of heat. You can however fit strip heat sinks that extend outside the potting compound.

The 832TC is a thermally conductive potting compound, but I was concerned about the aluminum oxide whether it would attenuate the Bluetooth signals.

 

[dknguyen]

When I was working at a place over the summer, we had cellular modems I was making a tester for. What he said was make sure your code works with both potted and unpotted because a while back testers for some other modems stopped didn't work with potted modems. One of the guys sat down and measured everything and it turned out the startup times were longer for the potted modems than unpotted and the tester firmware had to account for that.

BUt isn't the antenna not supposed to be potted in the first place?

No potting mix will dissipate heat, in fact all of them insulate because they are poor conductors of heat. You can however fit strip heat sinks that extend outside the potting compound.

Surely they can't be worse conductors of heat than air? And since it's potting it's in direct contact with the electronics- it's not like sticking electronics inside a sealed box where the air can't circulate and just gets hotter and hotter. In this case the heat source is in direct contact with the potting compound which is then transferring the heat to the air. I would think it improves cooling. Usually you don't stick hot things in enclosed AIR spaces because the air is a terrible thermal conductor and can't circulate. BUt if you're surrounded by something that is a better thermal conductor than air, it's completely different. Surely you don't think that if potted some electronics in some kind of magical non-conductive metal that it would run hotter? Almost anything is a better thermal conductor than air.