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

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luvdunhill

luvdunhill

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Joined 2006
#1
So, I'm trying to gauge interest in this. I discovered this product from EUVL (Patrick) in the following thread:

http://www.diyaudio.com/forums/showthread.php?threadid=37262&perpage=25&pagenumber=1

I ordered a sample piece and cut it myself and got very good results. Patrick also posts some results in the above thread.

The specific product I'm interested in doing a group buy on is the new Keratherm Red 86/83, which performs even better. Datasheet is here:

http://kerafol.de/jml/pdfdocs/thermalmanagement/db/eng/Keratherm_rot_eng.pdf

I've contacted the US distributor and the MOQ is 1000. I've selected two precut sizes that I think will work quite well. The A and B dimensions are length and width, and the C dimension is the distance from the top to the center of the mounting hole, and D is the diameter of the hole. The dimensions in millimeters are as follows:

TO-220:
A: 18,0
B: 12,0
C: 4,5
D: 3,0

TO-247:
A: 32,0
B: 23,0
C: 7,0
D: 3,0

Both pads are 0.25mm thick.

At the moment, the cost for the TO-220 is $0.25 each and TO-247 is $0.76 each in MOQ of 1000. Shipping from me to you should be very cheap, as these can fit in a envelope with minimal weight piece of cardboard added for rigidity.

I personally have a use for ~600 of the TO-220 isolators, so there is no doubt in my mind that we can go forward with that part of the GB. My use for the TO-247 size is smaller, but I'm guessing that's what most people around here want.

Notice the pricing is around half that of the highest performing Bergquist isolators available at Digikey at a significant bump in performance. I'll leave it to you to decide if it is worth it for your application.

Anyways, my feelings won't get hurt if this GB doesn't get off the ground 🙂 At this point in time, nothing is official, just trying to get an idea of the interest. Most likely I will have a minimum order size, but it's too early to state what that will be. In the past it's always been around $25, but I may lower that for this particular GB.

Thanks guys!
-Marc
 
#2
Hi Marc,

600? Going pro, eh? 😉

Maybe you want to consider buying a few sheets in addition to the precuts, there are a number of nice parts out there that do not use standard packages, like the 2SK1530.

Have fun, Hannes
 
#3
h_a said:
Maybe you want to consider buying a few sheets in addition to the precuts, there are a number of nice parts out there that do not use standard packages, like the 2SK1530.
Click to expand...

Cutting the sheets is an experience I don't really want to do again 🙂 Getting the hole exactly the right size with no shearing was kinda tricky... well, that and finding metric sized hole punches. It's hard to "aim" the hole punch, as many do not have a way to center the punch on a marked dot, for example. I just was concerned about the long term stability of this process.
 
#12
AndrewT said:
32mm x 23mm is enormous for a To247.
It will easily fit a To264. More than 2mm spare around every edge.
Click to expand...

Yes, perhaps your correct. I was erroneously calling the 2SJ201 a TO-247, which I see is not correct. Is it a TO-3P? In which case ( :clown: ) , this package must vary tremendously.

So, I guess Hannes, it will fit 2SK1530 🙂

Andrew, are you recommending that we look at a smaller size?
 
#13
I like the bigger size -- more flexibility: you can shave down but not add width. And it doesn't hurt anything.

With 2mm (0.08") overhang on each, you only need to mount transistors 4mm or a hair under 3/16" spacing between the transistors to avoid overlap.

Just my :2c:
 
#17
o, I guess Hannes, it will fit 2SK1530
Click to expand...

I'm glad to hear that as I didn't bother to look at the dimensions.

Better don't rely on that in general, you know there exist people that order TO-247 Silpad heatpads and jeez they don't fit a 2SK1530. 😀

But the same people coudn't be held back to change the design in the last minute as initially other fets (real TO-247) were planned 😀

So what - the perfect excuse to order some sheets of Kerafol :clown: Thanks for digging out the old post 🙂

Have fun, Hannes
 
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