AL Oxide Pads
Has anyone tried the aluminum oxide pads from Aavid-Thermalloy? According to an app note I have from Motorola, they are superior to anything else (except beryllium), thickness accounted for.
However, this was written before Keratherm came across the ocean...
Has anyone tried the aluminum oxide pads from Aavid-Thermalloy? According to an app note I have from Motorola, they are superior to anything else (except beryllium), thickness accounted for.
However, this was written before Keratherm came across the ocean...
I tried them on a test rig, seemed to be around 1°C/W with a light smear of grease, IIRC. Measurement was with a contact thermometer on drain tab and sink.
Hmm, I will have to dig them out for my AJ build.
Hmm, I will have to dig them out for my AJ build.
Keratherm 86/82 is way better than AlO2, twice better.
(Beryllium Oxide is toxic and difficult to obtain)
http://www.diyaudio.com/forums/solid-state/31077-krell-ksa-50-pcb-99.html#post777532
Not surprising...as said, that app note was out before Keratherm. Nonetheless, I will try both and see what the heat sink says, just for the sake of posting a comparison table.
I'm also trying to decode the thermal resistance numbers from heatsinkusa's website. They are saying for P/N "4.600" Wide Extruded Aluminum Heatsink", it's 1.4 C/W/3" . That should be 3" length...? So for a length of 9", thermal resistance should be 1.4/3 = 0.47C/W for the 8" piece.
Look right?
It works out to be about .7 for doubling in length. So 1°C/W/3" would be .7C/W at 6"
Aavid had a calculator on its website if you are using one of the common profiles. for example http://www.aavid.com/products/extrusion-heatsinks/65535
Note that it also depends on the delta T between sink and ambient. Aavid shows this on their pages. Helpful.
Aavid had a calculator on its website if you are using one of the common profiles. for example http://www.aavid.com/products/extrusion-heatsinks/65535
Note that it also depends on the delta T between sink and ambient. Aavid shows this on their pages. Helpful.
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The link you sent was very useful. As ZM pointed out, and after some refresher reading on thermal transfer, indeed a non-linear relationship. Thanks!
(u2, ZM) 😀
In my local suppliers Bc550 and ZTX 450 are both out of stock !! They have BC547B, the only difference is min hfe is 200 for the BC547 and 110 for the BC550. Will thiss matter?
