LM4780 insulators?

head_spaz · 4th December 2006, 04:20 AM

The large TO_220 is an unusually large die.
The generic one-size-fits-all insulators are not ideal.
Q-Pad materials are carbon fiber based, and are electrically conductive.

So what's the alternative? .... silpad in sheets?

What are you using for LM4780 insulators?
Part numbers?
Suppliers?
Bulk materials?

Anyone have some extra stock laying around?

VLSI · 4th December 2006, 09:17 AM

I use Mica washers for the MT-200 package (used for 2SA1216/2SC2922 etc.) it’s not perfect, as the whole spacing should be 1mm wider.
I have mounted about 8 LM4780 devices so far and have had no trouble with them (yet)
Use the best thermal conducting paste you can find, Try the silver loaded stuff for a computer CPU.
Also you could try mounting the LM4780 directly to a good size chunk of thick copper (with paste) and then insulate that from the heatsink.

Nordic · 4th December 2006, 10:08 AM

Its a shame the sinks are made of aluminium otherwise you'd love Coollaboratory Liquid Pro

Sadly this stuff will eat regular heatsinks for breakfast.

Quote:

"Coollaboratory liquid metal" consists of a liquid metal alloy at a 100%. It does not contain any non-metallic additives like silicone, oxides etc. It does not include any solid components either. Due to this composition, which is completely new for heat conducting pastes, it surpasses the best previously existing heat conducting pastes in the heat conductivity value by the factor 9-10, more simple heat conducting pastes by the factor 100. "Coollaboratory liquid metal" is optimised in its composition for the application with high-quality copper coolers, and can also be used with gold and silver plated coolers (such as some waterblocks).

CarlosT · 4th December 2006, 02:16 PM

Wakefield kapton washers 175-6-280P...perfect for LM3875 and other similar .8" x .8" TO220s.

http://www.wakefield.com/pdf/accessories.pdf

Minion · 5th December 2006, 12:14 AM

I have tried Pieces of tempered Glass with heatsink compound on either side and Have gotten fair results.....

The hard part was drilling the Screw hole through the Glass without breaking it but once I got that figured out it actually worked pretty well....

Cheers

BrianDonegan · 5th December 2006, 02:46 AM

For LM3886 and 3875 you can use Bergquist pads. Digikey# BER118-ND is a kapton-based pad (K10). Highly recommend.

traw · 5th December 2006, 05:52 AM

shoot, can not find the baggie with the part number. it was from digikey. search the catalog pages i guess.

traw · 5th December 2006, 05:53 AM

i can mail you this sheet of 4 if you like

BrianDonegan · 5th December 2006, 11:04 AM

Digikey BER117-ND

CarlosT · 5th December 2006, 11:51 AM

The Wakefield stuff is cheaper...well like by about the cost of a small cup'o'joe

4th December 2006, 04:20 AM	#1
head_spaz diyAudio Member Join Date: Mar 2004 Location: Arkansas	LM4780 insulators? The large TO_220 is an unusually large die. The generic one-size-fits-all insulators are not ideal. Q-Pad materials are carbon fiber based, and are electrically conductive. So what's the alternative? .... silpad in sheets? What are you using for LM4780 insulators? Part numbers? Suppliers? Bulk materials? Anyone have some extra stock laying around? __________________ Writing is good exercize for the texticles!

5th December 2006, 02:46 AM	#6
BrianDonegan diyAudio Member Join Date: Dec 2004 Location: Rock Ridge	For LM3886 and 3875 you can use Bergquist pads. Digikey# BER118-ND is a kapton-based pad (K10). Highly recommend. __________________ Twisted Pear Audio

5th December 2006, 11:04 AM	#9
BrianDonegan diyAudio Member Join Date: Dec 2004 Location: Rock Ridge	Digikey BER117-ND __________________ Twisted Pear Audio

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4th December 2006, 09:17 AM	#2
VLSI diyAudio Member Join Date: Nov 2006	I use Mica washers for the MT-200 package (used for 2SA1216/2SC2922 etc.) it’s not perfect, as the whole spacing should be 1mm wider. I have mounted about 8 LM4780 devices so far and have had no trouble with them (yet) Use the best thermal conducting paste you can find, Try the silver loaded stuff for a computer CPU. Also you could try mounting the LM4780 directly to a good size chunk of thick copper (with paste) and then insulate that from the heatsink.

4th December 2006, 02:16 PM	#4
CarlosT diyAudio Member Join Date: Oct 2006	Wakefield kapton washers 175-6-280P...perfect for LM3875 and other similar .8" x .8" TO220s. http://www.wakefield.com/pdf/accessories.pdf

5th December 2006, 12:14 AM	#5
Minion diyAudio Member Join Date: May 2006	I have tried Pieces of tempered Glass with heatsink compound on either side and Have gotten fair results..... The hard part was drilling the Screw hole through the Glass without breaking it but once I got that figured out it actually worked pretty well.... Cheers

5th December 2006, 05:53 AM	#8
traw diyAudio Member Join Date: Sep 2005	i can mail you this sheet of 4 if you like

5th December 2006, 11:51 AM	#10
CarlosT diyAudio Member Join Date: Oct 2006	The Wakefield stuff is cheaper...well like by about the cost of a small cup'o'joe

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