GB: Kerafol Keratherm Red Isolators (TO-220 / TO-247)

[zhoufang]

I might be offering these Keratherm to everyone.
Price will be close to the price here (at least for TO-247), provided you get at least 50 pcs.

For TO-220, there is two type:
one is the type here: 18mm x 12mm
another is: 19mm x 14mm
FYI, a typical TO-220 chip is 15x10, so the bigger one offers 2mm per edge, which might be very useful if you use non-insulating thermal grease like arctic silver
The difference of cost is about 5-10 cents.

For TO-247 I think the 32x23 size here is very good and I will stick to it.

For uncut sheet, there is a 34mm x 27mm square sheet without any hole, which is plenty to cover any common package.
I think pads without hole will be good for clip mounting (rather than screw mounting), especially if you want to use conductive thermal grease.
Due to the lower volume I expect, and the larger size, the cost is expected to be between 150%-200% that of the 32x23 TO-247.

Let me know which TO-220 size you prefer, and what do you think about the 34x27 sheet without hole.

[tinitus]

Originally Posted by zhoufang

which might be very useful if you use non-insulating thermal grease like arctic silver

If this keratherm works as promised, I would expect it to loose its advantage if you use thermal grease

non-insulating arctic silver ?
sounds dangerous to me
could it make short connection through the hole at mounting screw ?

But I would still be interested in raw uncut sheets, in a size that fits into an envelope
But not an option, I suppose

[EUVL]

You miss the point completely. The stuff requires NO grease, just like Silpad.
But unlike Silpad, or mica with Whatever grease, it has a maximum temperature difference of 5°C at 30W dissipation on a TO247/TO3P.

I have been using the stuff for years (since 2006), have measured enough examples in enough different applications myself.
I am also the one who made it know to the Pass forum.
So the stuff works, as long as you use it properly, like NO grease.

See :
Mica and Goop

Even the fragility of the foil is public since 2006 !!


Patrick


PS You can get A4 sized uncut sheets (which is what I use) if you buy enough. But you need ceramic scissors to cut them properly. Or at least use a brand new one which will be no good for anything else after finishing one A4 sheet. The foil is ceramic powders embedded in plastic matrix.

[EUVL]

A dated application from January 2007.

Patrick

PS The 4x TO247s are power film resistors and do not require additional electrical insulation.

_______

[zhoufang]

Thanks everyone for pointing out the points.
It is good to know that grease is not needed.

Their 86/81 is without Glass fibre and I wonder it might be easier to cut.

[EUVL]

I should expect that you, as a respectable gentleman, would get some samples of the stuff, try it out, understand the function and the performance, before you would open a new thread to offer it to fellow DIYers, just like Marc did here (irrespective of motivation).

Best regards,
Patrick

[EUVL]

As already mentioned in August 2007 :

Mica and Goop
WÄRMELEITFOL.86/82 ROT 190X190X0,25 MM im Conrad Online Shop

for those who lives in continental Europe and wish to experiment.

Plus a whole variety of others :

http://www.conrad.de/ce/de/FastSearc...e&initial=true

and you do not need to buy 1000 pieces if you only want one.


Patrick

[zhoufang]

Thank you Patrick again for your kind suggestions and the direct links!
I spend most of the time looking at various datasheets, and I admit I had yet to have a physically look at one of these.
I was assuming that since many here is using it (though the fragility), and the datasheet figure and user report all confirms the excellent thermal property, this produce should be rather good for our purpose.
I'm on my way to get some TO-247 transistors for sale, and wants to offer these isolation pad to provide some convenience for my future buyers, as I myself find it hard to get a small quantity of high performance isolation pad in a cost effective and easy way at where I live. So I do need a large quantity of these.
I fully agree with you that Marc had done an excellent service here which is beyond what an average person would, myself included for sure.

Zhou Fang

[woody]

Is it too late to pick a few of these up? I need 8 of them for to-247 devices.

[npapp]

Hello, I am interested in a small sheet. 1x 200mmx200mm or 2 100mmx200mm sheets. Any thoughts on the price?

Patrick, I see that conrad has a sheet that fits my needs, but I don't think they ship to the US. Do you know of any other vendors selling small sheets?

Nick