PLEASE HELP! Insulating Transistors Electrically from Heat Sink - Page 2

Enzo · 9th November 2009, 04:14 AM

Look at Digikey (for example) and enter "Silpad" in the search box.

That is a brand name for a silicone insulator, made by Bergquist

For example the TO247 one ought to fit your larger transistor:
Digi-Key - BER178-ND (Manufacturer - SP900S-104)

Their part number BER178 if my link doesn't work

Steve Dunlap · 9th November 2009, 04:23 PM

Those work very well, I've used them for years. As a bonus heat sink compound is not required with them so they are much less messy.

Andrew Eckhardt · 9th November 2009, 04:30 PM

If you have hard anodized sinks you may not need anything more than thermal grease and isolated mounting. This has worked well for some manufacturers in the past, and creates a minimum thermal resistance interface.

Do It Yourself · 9th November 2009, 05:41 PM

yes.... it may be cheap.... but finding them????

Steve Dunlap · 9th November 2009, 06:50 PM

Quote:

Originally Posted by Do It Yourself

yes.... it may be cheap.... but finding them????

The link ENZO gave, Mouser, MCM just to name the obvious.

jleaman · 9th November 2009, 07:07 PM

I say look on ebay, or buy from the suggested places, why build something that will just blow up, then you will be replacing the transistors that you burnt up.

What about buying the iso pad's from the source that you got the transistors from ?

J'

CBRworm · 9th November 2009, 07:27 PM

I can second that you should not use regular Arctic Silver 5 - I tried it and sent about 180 volts through it around the mica.

I am comfortable with mica/white grease or silpads - I have used thermasil brand with good results.

sam9 · 1st December 2009, 01:46 AM

Kapton tape works well. Just keep all the sufaces clean and smooth since it punctures easily.

rfj5106 · 4th November 2011, 08:41 AM

Can anybody explain the pro's and con's of using silica pads over mica washers and thermal grease? Should you use thermal grease with silica pads? I have always used mica insulators with grease but latrly I have noticed pads being used and it looks like no grease. So the pads don't need grease?

woody · 4th November 2011, 09:35 AM

The silica pads are easier to use but at least the comon ones don't transfer heat
as well as the mica. There are much more expensive silica pad type ones in the $1
each price range that do transfer heat a lot better but for a price performance standpoint mica is still hard tobeat.

4th November 2011, 08:41 AM	#19
rfj5106 diyAudio Member Join Date: Mar 2006 Location: Richmond, B.C CANADA	Can anybody explain the pro's and con's of using silica pads over mica washers and thermal grease? Should you use thermal grease with silica pads? I have always used mica insulators with grease but latrly I have noticed pads being used and it looks like no grease. So the pads don't need grease? __________________ Richard Jenkins

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9th November 2009, 04:14 AM	#11
Enzo diyAudio Member Join Date: Sep 2004 Location: Lansing, Michigan	Look at Digikey (for example) and enter "Silpad" in the search box. That is a brand name for a silicone insulator, made by Bergquist For example the TO247 one ought to fit your larger transistor: Digi-Key - BER178-ND (Manufacturer - SP900S-104) Their part number BER178 if my link doesn't work

9th November 2009, 04:23 PM	#12
Steve Dunlap diyAudio Member Join Date: Sep 2008 Location: Here	Those work very well, I've used them for years. As a bonus heat sink compound is not required with them so they are much less messy.

9th November 2009, 04:30 PM	#13
Andrew Eckhardt diyAudio Member Join Date: Nov 2005 Location: PA	If you have hard anodized sinks you may not need anything more than thermal grease and isolated mounting. This has worked well for some manufacturers in the past, and creates a minimum thermal resistance interface.

9th November 2009, 05:41 PM	#14
Do It Yourself diyAudio Member Join Date: Nov 2009	yes.... it may be cheap.... but finding them????

9th November 2009, 07:07 PM	#16
jleaman diyAudio Member Join Date: Apr 2002 Location: Nanaimo	I say look on ebay, or buy from the suggested places, why build something that will just blow up, then you will be replacing the transistors that you burnt up. What about buying the iso pad's from the source that you got the transistors from ? J'

9th November 2009, 07:27 PM	#17
CBRworm diyAudio Member Join Date: Jan 2007 Location: S. Florida	I can second that you should not use regular Arctic Silver 5 - I tried it and sent about 180 volts through it around the mica. I am comfortable with mica/white grease or silpads - I have used thermasil brand with good results.

1st December 2009, 01:46 AM	#18
sam9 diyAudio Member Join Date: Jun 2002 Location: Left Coast	Kapton tape works well. Just keep all the sufaces clean and smooth since it punctures easily.

4th November 2011, 09:35 AM	#20
woody diyAudio Member Join Date: Jan 2002 Location: Tyrone Ga. U.S.A.	The silica pads are easier to use but at least the comon ones don't transfer heat as well as the mica. There are much more expensive silica pad type ones in the $1 each price range that do transfer heat a lot better but for a price performance standpoint mica is still hard tobeat.

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