Netlist said:
Thanks Hugo, great topic!!!
XEAGLEKEEPER said:Has anyone ever used beryllium oxide isolators ? Beryllium oxide is carcinogenic and poses health risks if inhaled. I know it is used in traveling wave tubes TWT's for rapid heat transfer to cold plates in Hi-power RF amplifiers( mil-aircraft). Any thoughts ?
I used berillium ceramic for hybrid ICs. Also, long time ago I had mil spec TO-3 pads made of berillium ceramic. But I don't remember details.
Why I started the thread, silicone pads look attractive, and I wandered, what if to use them instead of mica pads.
EUVL said:
But then diamond is even better, isn't it ?
Patrick
hey can I borrow your CVD chamber to lay a coat of diamond on my anodized heatsink?
BlackCatSound said:Bergquist make kapton and also Boron nitride loaded silicon pre-cut transistor insulators.
How do they look?
XEAGLEKEEPER said:I've used both the mica/silicone compound and the sil-pads. I like the sil-pads due to ease of installation and no white silicone grease everywhere its not suppose to be .
They look to me attrcative too, because of the same reason, but what about thermal conductivity, is it the same?
Hi,
the thermally conductive pads have a large variation in thermal performance.
A ratio of 3:1 is common from best to worst.
The worst is much worse than 0.002inch mica and thermal grease on both sides. But better than mica put in dry.
Choose carefully. Performance seems to be proportional to price.
the thermally conductive pads have a large variation in thermal performance.
A ratio of 3:1 is common from best to worst.
The worst is much worse than 0.002inch mica and thermal grease on both sides. But better than mica put in dry.
Choose carefully. Performance seems to be proportional to price.
AndrewT is right !
I always use mica for audio amplifiers, because of the critical importance of the thermal transfer, in order to reduce thermal transient intermodulation distorsion (class B).
But silicon pads are more secure for high voltage, switching power supplies, video amplifiers, etc.
Mica pads necessite more precise surface machining than silicon pads, for both transistor and heatsink. Carefully inspection and cleaning are essential !
Apologies for mispelling and other barbarisms ;-)
I always use mica for audio amplifiers, because of the critical importance of the thermal transfer, in order to reduce thermal transient intermodulation distorsion (class B).
But silicon pads are more secure for high voltage, switching power supplies, video amplifiers, etc.
Mica pads necessite more precise surface machining than silicon pads, for both transistor and heatsink. Carefully inspection and cleaning are essential !
Apologies for mispelling and other barbarisms ;-)
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