Mounting LU1014D

Gyuri · 12th August 2006, 09:03 AM

When building ZV9 there is a problem: mounting the Power J-FET's
on the heatsink. I have an idea that I would like to share with you. I solder the fets to a copper plate with a hot air gun. Then I throw it in to water allowing it to cool immediately. Then I screw it to the heatsink, with mica insulator. I don't know whether it's working or not but it seems the fet survived the process. I'm waiting for your opinions. Here is a pic:
(More pics and comments soon.)

Netlist · 12th August 2006, 09:28 AM

Thanks for sharing.
Instinctively, I'd skip the immediate cooling to not shock the different metals.

/Hugo

Gyuri · 12th August 2006, 10:09 AM

Netlist, thanks for the reply.
You are right but what about the maximum allowed heat stress ?
(It's 260 °C, over 10 sec.)

Gyuri

lucpes · 12th August 2006, 10:26 AM

Quote:

Originally posted by Gyuri
Netlist, thanks for the reply.
You are right but what about the maximum allowed heat stress ?
(It's 260 °C, over 10 sec.)

Gyuri

Well, maybe putting it in a shallow water with just the copper partly immersed would help. BTW, a thinner & smaller piece of copper would also do the job nicely and would be easier to adapt to your purposes.

Netlist · 12th August 2006, 10:30 AM

I’d go for the smallest possible copper plate, still allowing you to drill holes for mounting.
Then, tinning that plate and solder the component when the copper is still hot will probably take less then 10 seconds with a good iron. I admit I did not try it but should.

/Hugo

Gyuri · 12th August 2006, 02:33 PM

Netlist was right. Throwing into water is a medieval method. Don't try it ! (Unless you want to see inside the fet.) The fast temperature change will destroy the fet mechanically. Despite this
the idea is good only cooling method was wrong. Next try I put the copper plate with the fet on a wet cloth. It was good.
Gyuri

flg · 12th August 2006, 04:02 PM

2 more cents... The copper spreader is a good idea. But, why not just use Arctic Sliver directly to the copper and clamp it on??? The thj of that stuff is absolutely minimal

woody · 23rd September 2009, 06:10 PM

I have already started cutting a few copper blanks but still am hunting
a good easy way to clamp that little fellow down any ideas? How does
Nelson do it?

Magura · 23rd September 2009, 06:20 PM

JFET's ready for abuse

See this thread.

Magura

woody · 23rd September 2009, 06:53 PM

Thanks for the responce but I was asking about mounting the jfet without soldering
it. Like Nelson posted that he mounts his directly to the heatsink with just thermal
compound relying on the insulating properties of the anodized heatsink. But how does he
hold it on the heatsink?

23rd September 2009, 06:20 PM	#9
Magura diyAudio Member Join Date: Oct 2003 Location: Denmark, Viborg	JFET's ready for abuse See this thread. Magura __________________ Everything is possible....to do the impossible just takes a little while longer. www.class-a-labs.com

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12th August 2006, 09:28 AM	#2
Netlist diyAudio Moderator Join Date: Jan 2003	Thanks for sharing. Instinctively, I'd skip the immediate cooling to not shock the different metals. /Hugo

12th August 2006, 10:09 AM	#3
Gyuri diyAudio Member Join Date: Nov 2003 Location: Budapest	Netlist, thanks for the reply. You are right but what about the maximum allowed heat stress ? (It's 260 °C, over 10 sec.) Gyuri

12th August 2006, 10:30 AM	#5
Netlist diyAudio Moderator Join Date: Jan 2003	I’d go for the smallest possible copper plate, still allowing you to drill holes for mounting. Then, tinning that plate and solder the component when the copper is still hot will probably take less then 10 seconds with a good iron. I admit I did not try it but should. /Hugo

12th August 2006, 02:33 PM	#6
Gyuri diyAudio Member Join Date: Nov 2003 Location: Budapest	Netlist was right. Throwing into water is a medieval method. Don't try it ! (Unless you want to see inside the fet.) The fast temperature change will destroy the fet mechanically. Despite this the idea is good only cooling method was wrong. Next try I put the copper plate with the fet on a wet cloth. It was good. Gyuri

12th August 2006, 04:02 PM	#7
flg diyAudio Member Join Date: Jul 2005 Location: North East	2 more cents... The copper spreader is a good idea. But, why not just use Arctic Sliver directly to the copper and clamp it on??? The thj of that stuff is absolutely minimal

23rd September 2009, 06:53 PM	#10
woody diyAudio Member Join Date: Jan 2002 Location: Tyrone Ga. U.S.A.	Thanks for the responce but I was asking about mounting the jfet without soldering it. Like Nelson posted that he mounts his directly to the heatsink with just thermal compound relying on the insulating properties of the anodized heatsink. But how does he hold it on the heatsink?

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