The Wolverine 5th Group buy

[STOXX]

I'd prefer to stick to old fashion mica. All those 'rubber pads' put me off over the years.
In tune with this theme, thermal cameras have become affordable to all.
A thermal gun is like $50
An image gun is like $175
Cheers.

 

[Pars]

They've been using the aluminum nitride pads for Kevin Gilmore's electrostatic headphone amps for several years now and they work very well. KGSS Carbon, Megatron, his redesigned Stax T2, etc. I'd use them.

 

[danieljw]

I'd prefer to stick to old fashion mica. All those 'rubber pads' put me off over the years.
In tune with this theme, thermal cameras have become affordable to all.
A thermal gun is like $50
An image gun is like $175
Cheers.

These are not rubber they are like a little glass tile almost, the thermal conductivity is alot better than mica, although mica is decent.

 

[STOXX]

Who knows what people are using exactly without particular part#s or data sheets but I have hundreds of these tile-like spacers in several variations, thicknesses and they are terrible! I've tried everything under the sun since 2005 and nothing out performs hand selected mica with paste. Somebody tried to tell me two part epoxy from JB Weld was an insulator. Ha, I had to laugh. Now, you don't be wanting to use that on your semiconductors. That worked 100% on an insulated package of LM3886s in an industrial application. You have to test these things and measure them. That is why I am stuck with mica forever.

 

[Lorado]

HI Daniel,

Thanks for your tips about these new thermal pads.
I have a few questions:
I looked up the specs and Aluminium Nitride seems to be a kind of ceramic material (https://www.innovacera.com/product/aluminum-nitride-ceramic-thermal-pads). They are made in different sizes and thicknesses, but they only sell them by the 1000. Where can I buy let's say around 50 of them?
(Mouser nor DigiKey seem to stock them (yet)).
Do you need to put on thermal paste as well on these AlNi pads?
How thick would they need to be for power transistors like MJL4281 / MJL4302 TO-264?

BTW, did you make that aluminium spreader bar yourself, and if so, what are the dimensions?

Cheers, Wouter

 

[danieljw]

Hi Wouter,

There is a link in the build thread to the pads.
Yes you need paste with these & yes they are ceramic like feel but made from Aluminium Nitride.

Aluminium spreader bar is 16 mm aluminium from Bunnings it is inexpensive and black already I just marked it up and drilled it 🙂

 

[dovla83]

During some testing which pushed the thermal limits a lot harder than usual, I had a batch of silicon insulator pads which were not very good and I lost a couple of output devices

What was the rail voltage and size of the heatsinks/chassis?