lowell 5/16/2017 11:16 AM
Thermally Conductive Insulating sheets
Will this stuff work for the average repair involving heatsinking power transistors? Been working on JBL EON speakers and one came back again. The service update says there may be metal shavings in the insulating pad. I'd like to have some bulk sheets around to cut new pieces from. Not sure on the thickness spec. .2mm and .5mm seem common, this one is .2mm.

http://www.mouser.com/ProductDetail/...MiFcRBPaD3U%3d
 
lowell 5/16/2017 11:17 AM
This one is .5mm. More than double the price. http://www.mouser.com/ProductDetail/...RWSSWTXRaoQ%3d
 
Randall 5/16/2017 11:23 AM
$26 plus shipping for a 9" x 9" piece of insulator? What the heck is this stuff made of, unicorn mane?
 
eschertron 5/16/2017 11:31 AM
Quote Originally Posted by Randall View Post
$26 plus shipping for a 9" x 9" piece of insulator? What the heck is this stuff made of, unicorn mane?
Organic, gluten-free unicorn mane

How many transistor-sized pieces would you make out that? 9" x 9" sounds like a year- to a lifetime- supply of the stuff.
 
lowell 5/16/2017 11:53 AM
Judging by the JBL repairs it'll last about 2 or 3 repairs. There is a pad in these that is about 6x4"
 
J M Fahey 5/16/2017 7:54 PM
Quote Originally Posted by lowell View Post
Judging by the JBL repairs it'll last about 2 or 3 repairs. There is a pad in these that is about 6x4"
WHAT component has a 6" x 4" case?
TO54748?
 
lowell 5/16/2017 8:30 PM
All eight devices use one large pad. 4 rectifiers and 4 mosfets.
 
eschertron 5/16/2017 8:35 PM
Quote Originally Posted by lowell View Post
All eight devices use one large pad. 4 rectifiers and 4 mosfets.
Well, maybe JBL can afford to throw away unicorn mane in such large quantities. I've only ever seen heatsink-sized pieces in use, maybe 1'' x 1.5" tops. In one sheet, that might take half the 6x4.
 
lowell 5/16/2017 9:28 PM
Agreed. However, there are no screws or holes in the heatsink, so the large pad ensures insulation once everything is screwed down into place.
 
Enzo 5/16/2017 9:37 PM
The data sheet for the stuff in your link calls it a phase change material, and gives a "softening" temperature. This sounds fancier than plain old silicone pads.
 
lowell 5/16/2017 9:47 PM
Right on. Well that's good news. I've asked this question before and couldnt find the thread. Any ideas on where to get silpad type of stuff in sheets or even rolls? Mouser and digi are a mindf÷=/k trying to find it.
 
lowell 5/16/2017 9:50 PM
Ooh how about this?
http://www.mouser.com/ProductDetail/...U2OmJbfuAcw%3d
 
Enzo 5/16/2017 10:04 PM
More like it.
 
asfi 5/18/2017 5:51 PM
Quote Originally Posted by lowell View Post
The big unknown when replacing heatsink insulators is what level of thermal performance is needed. If you're lucky enough to have a BOM with a (still sourceable) manufacturer's part number, you're golden. Otherwise, the safest approach is to get the most thermally conductive you can justify buying and go from there.

I've used this material for a variety of power supplies and amps. It cuts cleanly with a paper guillotine. It's only 35% more expensive than the Sil-pad 400 but its thermal performance is so so much better.

http://ca.mouser.com/ProductDetail/L...puo1PO2891Q%3d
 
lowell 5/18/2017 7:13 PM
Awesome thanks for the info!