mosfets

karma · 20th March 2003, 01:10 AM

when it comes to installing mosfets on a heat zinc what works better a single screw or 2 screw holes on each side and clamping it down.i wana try clamping it i just dont want to wast my time
if it does not work help

thanks......

Nelson Pass · 20th March 2003, 01:15 AM

Mounting the Mosfets as they were designed is pretty
adequate. I don't know of any manufacturer specifying
otherwise, and you could conceivably run into loss of seal
between the plastic and metal.

Circlotron · 20th March 2003, 01:17 AM

I like the clamp method because then the mosfet doesn't tend to pull down one end and lift up the other end. The force is more even over the whole of the back of the fet.

/Circlotron - not wanting to contradict Nelson Pass, quickly edits his posting.

For high voltage use it is often necessary to use a clamp to get the required creepage distance. If you are not going to work the fet too hard then using the hole is ok. For maximum thermal transfer I still like a clamp though because you can get the pressure right over the die area of the fet.

Nelson Pass · 20th March 2003, 01:26 AM

Contradict at will

I personally like the aesthetics of the clamp approach, but I think that when you reach the point where you need that "extra thermal transfer" you're probably already on thin ice.

pass/ - likes to stay within 25 watts on 150 watt devices

karma · 20th March 2003, 01:37 AM

i have one screw so ill leave it. wow zen amps run supper hot
whats the life span of a mosfet at this heat? and if i hose a mosfet
will it take the pcb with it?

Nelson Pass · 20th March 2003, 01:39 AM

What heat would that be?

karma · 20th March 2003, 01:48 AM

i dont have a tester but if i ground myself and then touch the fet its to hot to keep my finger on

Peter Daniel · 20th March 2003, 01:53 AM

You can reduce the heat with a fan. How hot is a heatsink, can you keep your hand on it?

Boxbldr681 · 20th March 2003, 01:58 AM

Suprise, suprise...
even with a good heat sink they are hot...too hot

Nelson Pass · 20th March 2003, 02:01 AM

So how many watts are you running them at?

20th March 2003, 01:10 AM	#1
karma diyAudio Member Join Date: Feb 2003 Location: hamilton,ontario	mosfets when it comes to installing mosfets on a heat zinc what works better a single screw or 2 screw holes on each side and clamping it down.i wana try clamping it i just dont want to wast my time if it does not work help thanks......

20th March 2003, 01:17 AM	#3
Circlotron diyAudio Member Join Date: Jun 2002 Location: Melbourne, Australia	I like the clamp method because then the mosfet doesn't tend to pull down one end and lift up the other end. The force is more even over the whole of the back of the fet. /Circlotron - not wanting to contradict Nelson Pass, quickly edits his posting. For high voltage use it is often necessary to use a clamp to get the required creepage distance. If you are not going to work the fet too hard then using the hole is ok. For maximum thermal transfer I still like a clamp though because you can get the pressure right over the die area of the fet. __________________ Best-ever T/S parameter spreadsheet. http://www.diyaudio.com/forums/multi...tml#post353269

20th March 2003, 01:37 AM	#5
karma diyAudio Member Join Date: Feb 2003 Location: hamilton,ontario	mossfets i have one screw so ill leave it. wow zen amps run supper hot whats the life span of a mosfet at this heat? and if i hose a mosfet will it take the pcb with it?

20th March 2003, 01:48 AM	#7
karma diyAudio Member Join Date: Feb 2003 Location: hamilton,ontario	hmm i dont have a tester but if i ground myself and then touch the fet its to hot to keep my finger on

20th March 2003, 01:53 AM	#8
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	You can reduce the heat with a fan. How hot is a heatsink, can you keep your hand on it? __________________ www.audiosector.com “Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC


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20th March 2003, 01:15 AM	#2
Nelson Pass The one and only Join Date: Mar 2001	Mounting the Mosfets as they were designed is pretty adequate. I don't know of any manufacturer specifying otherwise, and you could conceivably run into loss of seal between the plastic and metal.

20th March 2003, 01:26 AM	#4
Nelson Pass The one and only Join Date: Mar 2001	Contradict at will I personally like the aesthetics of the clamp approach, but I think that when you reach the point where you need that "extra thermal transfer" you're probably already on thin ice. pass/ - likes to stay within 25 watts on 150 watt devices

20th March 2003, 01:39 AM	#6
Nelson Pass The one and only Join Date: Mar 2001	What heat would that be?

20th March 2003, 01:58 AM	#9
Boxbldr681 diyAudio Member Join Date: Feb 2003 Location: Las Vegas	Suprise, suprise... even with a good heat sink they are hot...too hot

20th March 2003, 02:01 AM	#10
Nelson Pass The one and only Join Date: Mar 2001	So how many watts are you running them at?

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