Question For Electronics Techhie Nerds...

[MEXICOWANDERER]

Subject: mounting components using ceramic based adhesives...

More LED and power supply questions...

MOSFETS are supposed to be mounted with a Sil Pad. I've got heat sinks that do not get along with M3 screws, holes or threading...

Arctic Silver according to the gurus has just enough potential for capacitance to give engineers the willies.

I can only assume ceramic adhesive does not have this characteristic.

But what am I giving up in thermal heat transfer?

The same holds true for LED chips but the Arctic Silver is amazing in allowing thermal to transfer to the heat sink.

So it's a question of ceramic versus 200 Sil Pad thermal transfer.

[MEXICOWANDERER]

It's an LED control circuit using a MOSFET. Meaning a relay replacement. A matter of insulating the back (tab) of the MOSFET using ceramic adhesive. Arctic Silver cautioned me about "extremely small but the existence of" capacitance created with the use of their high silver content ultra slow dry silver adhesive.

I merely thought that ceramic (being ceramic is an electrical insulator) would as an acceptable electrical insulator without giving up too much heat transfer efficiency.

[wa8yxm]

If you are designing an LED power supply then I will assume it is a DC supply, Capacitance should not be an issue less you are using a retangle wave dimmer at fairly high frequency. I'd go with mica washers and artic Silver. (but them I am old school) Googled Sil-Pad, looks like it is a superior replacement for the Mica Washer.

Capacitance: Any time you put two slabs of metal close to each other with an inslator (Even air) between them,, You make a Capacitor, It does not matter what heat conductive stuff you put there, Artic Silver or something else, you have a Capacitor, No way around it.

As the plates come closer the capacitance incresases, as the smaller one gets bigger, Capacitance increases, Doubling up on the sil pads, Decreases it.