JFET's ready for abuse

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#21
Magura, those sure are nice. I however l don't intend to
push mine hard only ~8 or 9 w or so. So I decided to salvage a couple of blown itfp240 mosfets and remove almost all the plastic.
Then sand the dead active device off exposing the copper base
and solder the jfet there. I hope the indium solder that melts
at ~97 c doesn't melt when I use the devices! I put a healthy
Irf260p in the picture besides my soldered Jfet.
 

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#29
Magura said:

No, I use Kapton film
Magura 🙂
Click to expand...
Thickness?
Because I've only found 0.0015". Actually it was a while ago maybe it was 0.005" :xeye: At 5000V/.001" dielectric strength, the thinner the better as long as you've checked for burrs and high spots etc.!
Why not use Kapton as the dielectric in your Quasi T-Clad developement project? It's high temp. It even comes with tape goo from Office Depot. Maybe you can get good high temp goo and make real High Performance thermal substrates. I'ld respond by e-mail but I've had to shift gears and think about all that T-Clad stuff in order to respond with a good answer...
While I'm thinkin 'bout it. I think you would have reasonable reliability (real good for the Magura/C/W normal levels) starting at 10W and possibly as high as 20W for that device. N.P. suggests 10W as a max? I would say 20W. N.P. also talks about the Vds vs Ids and load line linearity. That is where 2-3Vds is important. If your doin 10-20W at 3V thats 3.5-6+ Amps. This aint an F3 clone 😉 😉 😉
But what could it be??? :bigeyes: :bigeyes: :bigeyes:
 
#35
flg said:

Thickness?
Because I've only found 0.0015". Actually it was a while ago maybe it was 0.005" :xeye: At 5000V/.001" dielectric strength, the thinner the better as long as you've checked for burrs and high spots etc.!
Why not use Kapton as the dielectric in your Quasi T-Clad developement project? It's high temp. It even comes with tape goo from Office Depot. Maybe you can get good high temp goo and make real High Performance thermal substrates. I'ld respond by e-mail but I've had to shift gears and think about all that T-Clad stuff in order to respond with a good answer...
While I'm thinkin 'bout it. I think you would have reasonable reliability (real good for the Magura/C/W normal levels) starting at 10W and possibly as high as 20W for that device. N.P. suggests 10W as a max? I would say 20W. N.P. also talks about the Vds vs Ids and load line linearity. That is where 2-3Vds is important. If your doin 10-20W at 3V thats 3.5-6+ Amps. This aint an F3 clone 😉 😉 😉
But what could it be??? :bigeyes: :bigeyes: :bigeyes:
Click to expand...


I can't remember how thick the Kapton film I have is, I bought it long ago.


Yeah, I see you get the picture of where I'm heading 😉

Kapton will though not be an option, as the thermal cycling will be a deal breaker.

Magura 🙂
 
#36
Hey Magura, What about Mica between the primary copper heat spreader and the main heatsink? I may be wrong, but I seem to remember that mica is a better heat conductor and better electrical insulator than most of the synthetic insulator materials. Only thing that is an issue is that it's hard to get nice flat, planar pieces of mica.


Peace,

Dave

P.S. you could also go synthetic diamond, but that might move the cost up just a bit.😀 😉
 
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