Hi guys, I have come across some salvaged heatsinks.
Along with the heatsink, have come only what I can only describe as "ceramic insulators" - I think.
I have never seen these before.
See image attached.
They are white in colour and have a silver/white paste on them which I assume is a thermal paste.
My question being do these serve the same purpose as mica washers. I expect that they do exactly the same thing. Do they have a low thermal resistance, can I mount a power MOSFET on them and expect to get good thermal conductivity, assuming I can drill a hole in them?
I should say they are 1mm thick.
Thanks for reading and hopefully your answers.
Along with the heatsink, have come only what I can only describe as "ceramic insulators" - I think.
I have never seen these before.
See image attached.
They are white in colour and have a silver/white paste on them which I assume is a thermal paste.
My question being do these serve the same purpose as mica washers. I expect that they do exactly the same thing. Do they have a low thermal resistance, can I mount a power MOSFET on them and expect to get good thermal conductivity, assuming I can drill a hole in them?
I should say they are 1mm thick.
Thanks for reading and hopefully your answers.
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They may be Alumina ceramic insulators. When the highly-vaunted Keratherm insulators I was using on my F5 Turbo mono blocks failed, I switched to Alumina ceramics. According to the literature, Alumina ceramic insulators have superior heat transference qualities and are longer-lasting than Keratherm and similar film insulators. They are moderately-priced as well. Check aliexpress for vendors.
Regards.
Regards.
I reckon you're correct SRMcGee, Alumina ceramic insulators. Thanks for your reply.
Can I ask have they been successful for you in your F5T?
speakes1:
Very much so. It hasn't been that long since I replaced the Keratherm insulators with the Alumina ceramics -- maybe 18 months -- but I don't regret moving away from the Keratherms. I also used Thermal Grizzly's Kryonaut, which was the best thermal paste I could find. Since then, I've used that combination in a few other projects as well (which shouldn't be a surprise, given that I bought 150 of the Alumina ceramic insulators).
Take this with a big grain of salt: for years, I liked the idea of using mica as an insulator because they were less susceptible to deterioration than film-based alternatives but shied away from them because of the thermal paste mess. The Alumina ceramic insulators have better thermal qualities than mica, and I screwed up a small dose of courage and discovered that I could control the thermal paste mess (frankly, the incentive was spending a ridiculous amount on the Kryonaut and not wanting to waste any of it). Of course, your mileage may vary.
Good luck on your project!
Regards,
Scott
Very much so. It hasn't been that long since I replaced the Keratherm insulators with the Alumina ceramics -- maybe 18 months -- but I don't regret moving away from the Keratherms. I also used Thermal Grizzly's Kryonaut, which was the best thermal paste I could find. Since then, I've used that combination in a few other projects as well (which shouldn't be a surprise, given that I bought 150 of the Alumina ceramic insulators).
Take this with a big grain of salt: for years, I liked the idea of using mica as an insulator because they were less susceptible to deterioration than film-based alternatives but shied away from them because of the thermal paste mess. The Alumina ceramic insulators have better thermal qualities than mica, and I screwed up a small dose of courage and discovered that I could control the thermal paste mess (frankly, the incentive was spending a ridiculous amount on the Kryonaut and not wanting to waste any of it). Of course, your mileage may vary.
Good luck on your project!
Regards,
Scott
Note that they could still be beryllia and you must exercise caution - beryllia is used a lot for RF as it has excellent RF properties as well as being an exceptionally good heat conductor (between copper and aluminium metal in fact, about 10 times better than alumina, and in fact better than beryllium itself!). There's no easy way to tell various ceramics apart without lab equipment, note.
Make sure they are not electrically conductive with a meter. They are most likely ceramic non conductive washers used so you can screw down a transistor without the screw touching the transistor and the heat sink causing a short.
There are lots on Amazon like this - anybody tried these? :
https://www.amazon.co.uk/Ceramic-Al...-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1
https://www.amazon.co.uk/Ceramic-Al...-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1
I use aluminum oxide insulators all the time in my Class A amplifier projects - superior heat transfer, especially if you use them with one of the better thermal pastes with Boron Ntride loading.
A quick search uncovered a number of options. Here are a couple:
https://www.aliexpress.us/item/2255...!sea!US!1746454576&curPageLogUid=QwuYrElpbcPs
https://www.aliexpress.us/item/3256...!sea!US!1746454576&curPageLogUid=yXCFa1Wad2oU
I have no special affinity for the vendor I purchased mine from, but here is their ad as well:
https://www.aliexpress.us/item/2251...tewayAdapt=glo2usa4itemAdapt&_randl_shipto=US
It appears the foregoing vendors have insulators in stock.
Regards.
https://www.aliexpress.us/item/2255...!sea!US!1746454576&curPageLogUid=QwuYrElpbcPs
https://www.aliexpress.us/item/3256...!sea!US!1746454576&curPageLogUid=yXCFa1Wad2oU
I have no special affinity for the vendor I purchased mine from, but here is their ad as well:
https://www.aliexpress.us/item/2251...tewayAdapt=glo2usa4itemAdapt&_randl_shipto=US
It appears the foregoing vendors have insulators in stock.
Regards.