Hi there.
I'm finally on the stage of installing the output trt's on my p101 project and now I'm having trouble with the heatsink/trt's isolation.
I have micas, sil-pads, something called "elastomeros" in spanish and about this one I cannot find information, the seller told me the "elastomeros" don't need silicon grease and should work fine.
It's the High power version, and Rod elliot doesn't recommend sil-pads, but I don't know the english word for "elastomeros".
I have the three of them, the "elastomeros" are gray-ish in colour and not rigid at all. Since the p101 attach the amp to the heatsink pretty hard, and almost impossible to put the fingers on the trt's once installed (bad idea, i know since the mosfets are sensitive to this "brute" testing), I always used micas, but recently I had a mica deffective and burnt the output trt's along with the driver.
Should I try these "Elastomeros"? Or go old-fashioned with micas?
I'm finally on the stage of installing the output trt's on my p101 project and now I'm having trouble with the heatsink/trt's isolation.
I have micas, sil-pads, something called "elastomeros" in spanish and about this one I cannot find information, the seller told me the "elastomeros" don't need silicon grease and should work fine.
It's the High power version, and Rod elliot doesn't recommend sil-pads, but I don't know the english word for "elastomeros".
I have the three of them, the "elastomeros" are gray-ish in colour and not rigid at all. Since the p101 attach the amp to the heatsink pretty hard, and almost impossible to put the fingers on the trt's once installed (bad idea, i know since the mosfets are sensitive to this "brute" testing), I always used micas, but recently I had a mica deffective and burnt the output trt's along with the driver.
Should I try these "Elastomeros"? Or go old-fashioned with micas?
Go for Mica and grease.
Elastomer insulators have pretty good thermal conductivity, unfortunately they are rather thick, which makes the C/W number inferior to Mica.
Elastomer insulators have pretty good thermal conductivity, unfortunately they are rather thick, which makes the C/W number inferior to Mica.
"Elastomeros" is likely a "silicone rubber washer" in English.
It is not the best for thermal conductivity.
As far as I know mica+thermal compound outperforms silicone washers if not too thick.
Lukas.
It is not the best for thermal conductivity.
As far as I know mica+thermal compound outperforms silicone washers if not too thick.
Lukas.
Sil-Pad as the trade name for silicon rubber insulators is, is about the worst.
Mica is better but aluminum oxide insulators are the best, but they are also the priciest wheres mica is among the cheapest.
Mica is better but aluminum oxide insulators are the best, but they are also the priciest wheres mica is among the cheapest.
I've used AlO2 insulators from the mid '80s (thick ones) till a few years ago (thin ones from Avid Thermalloy).
There's better nowadays, and it's pretty in pink
(compliments go to EUVL)
Attachments
I've never seen pink AlO insulators, only bluetac color and white, but then again i only used them once.
The Pink refers to Kerafol 86/82, the sheets which are on all sides of the text i posted.
(would have thought they were hard to miss)
(would have thought they were hard to miss)
Very intereresting, Jacco.I've used AlO2 insulators from the mid '80s (thick ones) till a few years ago (thin ones from Avid Thermalloy).
There's better nowadays, and it's pretty in pink
(compliments go to EUVL)
So this means this time ESP is wrong recommending Kapton ( I believe they also sell a tape of that material).
BTW what about the source of your numbers?
a) Scientific paper subjet to peer review (i.e. IEEE)
b) Commercial (then, most probably biased)
c) Own measurements
Personally I have mixed experience about insulators.
I believe the mounting is of the max importance, insulators come second. I mean a hex socket screw with a large washer and or better a large plate ensures very good results on modern plastic flats.
I have very good experience with the sili pads (3M) for series production stuff, since the result is very repeatable.
Mica is good if you do it carefully one by one with a good compound, but prone to mistakes and random bad pieces. BTW I could never find precut micas for nothing else that old TO3 or TO 220 / 126 and is difficult to cut by hand.
Kapton I used only once for hobby where I could not find nothing else and it is working so far. It didn´t feel so bad as your numbers would show, but, again, the mounting was accurate. I am thinking to make some measurements and tests, now that I know.
Didn't know...
I didn't know Rod sells the Kepton isolators. I sent him an e-mail, It was stupid of me not to ask when i purchased the p101 pcb.
Anyways, most of the isolators you recommend are not available in Spain, If anyone knows where to find them in the EU, please let me know.
Thanks again.
I didn't know Rod sells the Kepton isolators. I sent him an e-mail, It was stupid of me not to ask when i purchased the p101 pcb.
Anyways, most of the isolators you recommend are not available in Spain, If anyone knows where to find them in the EU, please let me know.
Thanks again.
EUVL's article in Linear Audio -Volume 3 by Jan Didden.
Patrick's formal education and experience level are just about the best credentials to have for this kind of thing, i'd think.
Folks have been wrong about Kapton for quite some time, Kapton vs Mica has been discussed on this forum several times.
Mr Elliott can't been right all the time.
As Patrick/EUVL, i've tried just about every insulator material over the years.
I have mica insulators in every size, including plenty of very hard to obtain MT200, still have some Kapton Bergquist K-10 sheet, AL2O3 insulators in several sizes. (+ oldy AL2O2 in 4.5mm, 2.9mm, and really expensive silicon sheet leftovers from the '80s)
Aluminum oxide insulators are not manufactured in MT200 size, to still use AL2O3 insulators i resized TO-247 ones with a diamond blade to reach a higher dissipation level than with mica.
=> http://www.diyaudio.com/forums/atta...25d1133198612-krell-ksa-50-pcb-thermalloy.jpg
The Keratherm red 86/82 is so much easier, i cut sheets accurately to size with a guillotine paper cutter (as it's so thin&flexible, the Keratherm on top of a sheet of paper).
Holes are just as easily punched, and the best part is that the pink stuff does without thermal goop. (thermal paste makes it perform worse)
For some devices, mounting bolts/screws still have to be isolated from the package.
I check for conductivity after mounting each device just the same, whatever the package, no matter whether the insulator is mica, aluminum oxide or Kerafol.
Old habits, better safe than sorry.
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How about this one:
/http://hongkong01.rs-online.com/web/p/thermally-conductive-insulators/7124018/
Not too expensive though.
/http://hongkong01.rs-online.com/web/p/thermally-conductive-insulators/7124018/
Not too expensive though.
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