"Pyrolytic Graphite"

[John Devereux]

"2-5 times higher thermal conductivity than copper"

I have not heard much about this wonder material, is it actually any use
for anything?


--

John Devereux

 

On Tuesday, August 18, 2015 at 7:55:34 AM UTC-7, John Devereux wrote:

"2-5 times higher thermal conductivity than copper"

I have not heard much about this wonder material, is it actually any use
for anything?

It's good but expensive. Certainly better than using plastic in modern disposable engines. I've been reading lots of horror stories on new car engines.

 

On Tuesday, August 18, 2015 at 9:16:44 AM UTC-7, Syd Rumpo wrote:

On 18/08/2015 16:21, edward.ming.lee@gmail.com wrote:
On Tuesday, August 18, 2015 at 7:55:34 AM UTC-7, John Devereux wrote:
"2-5 times higher thermal conductivity than copper"

I have not heard much about this wonder material, is it actually any use
for anything?

It's good but expensive. Certainly better than using plastic in modern disposable engines. I've been reading lots of horror stories on new car engines.

It's diamagnetic and lightweight, so it can hover above permanent magnets..

It would be good for replacing the plastic valve cover of my Camry. Most disposable engine like the Camry will be done when cooling is gone, mostly from the melted plastic cover. I am looking to replicate the cover in metal or PG. It might cost $1000 vs. $100 plastic cover, but cheaper than the $5000 engine.

 

[dcaster@krl.org]

On Tuesday, August 18, 2015 at 12:34:26 PM UTC-4, John Larkin wrote:

It's very anisotropic, with high thermal conductivity only in the
plane of a sheet. That makes it useless for most electronic
applications.



John Larkin Highland Technology, Inc
lunatic fringe electronics

But great for re entry nose cones and rocket nozzle liners.

Dan

 

On Tuesday, August 18, 2015 at 9:54:12 AM UTC-7, DecadentLinuxUserNumeroUno wrote:

On Tue, 18 Aug 2015 09:39:02 -0700 (PDT), edward.ming.lee@gmail.com Gave
us:

It would be good for replacing the plastic valve cover of my Camry.

Carbon fiber.

Thermo conduction is more important than strength. Or perhaps carbon fiber on top of PG. It needs to last for several minutes, when the water pump goes and before the engine explode. Modern disposable engines are built to last as long as the water pump, some are even made of plastic.

All the car customizers and chopper builders have connections for
metal plating, AL anodizing, carbon fiber stuff... all cheaper usually
than you can go find it. Make friends with a biker that has a custom
chopper *he* built.

Possible. First is to replicate a mold that can withstand 2000C for PG, or perhaps just 1000C for aluminum. The cover needs to be an exact replicate of the plastic one.

 

[whit3rd]

On Tuesday, August 18, 2015 at 7:55:34 AM UTC-7, John Devereux wrote:

"2-5 times higher thermal conductivity than copper"

I have not heard much about this wonder material, is it actually any use
for anything?

Well, yeah. It's the tooling material of choice for electrical discharge
machining (of the 'sinker' type, not wire-cutting). It also makes
a good susceptor for induction heating.
You can put graphite around a crucible, and get molten metal from your
kitchen microwave oven. Once, for sure.

 

[Syd Rumpo]

On 18/08/2015 16:21, edward.ming.lee@gmail.com wrote:

On Tuesday, August 18, 2015 at 7:55:34 AM UTC-7, John Devereux wrote:
"2-5 times higher thermal conductivity than copper"

I have not heard much about this wonder material, is it actually any use
for anything?

It's good but expensive. Certainly better than using plastic in modern disposable engines. I've been reading lots of horror stories on new car engines.

It's diamagnetic and lightweight, so it can hover above permanent magnets.

Cheers
--
Syd

 

[John Larkin]

On Tue, 18 Aug 2015 15:55:30 +0100, John Devereux
<john@devereux.me.uk> wrote:

"2-5 times higher thermal conductivity than copper"

It's very anisotropic, with high thermal conductivity only in the
plane of a sheet. That makes it useless for most electronic
applications.

I have not heard much about this wonder material, is it actually any use
for anything?

https://en.wikipedia.org/wiki/Pyrolytic_carbon#Applications


--

John Larkin Highland Technology, Inc
lunatic fringe electronics

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[DecadentLinuxUserNumeroUn]

On Tue, 18 Aug 2015 09:39:02 -0700 (PDT), edward.ming.lee@gmail.com Gave
us:

>It would be good for replacing the plastic valve cover of my Camry.

Carbon fiber.

All the car customizers and chopper builders have connections for
metal plating, AL anodizing, carbon fiber stuff... all cheaper usually
than you can go find it. Make friends with a biker that has a custom
chopper *he* built.

 

[John Devereux]

John Larkin <jlarkin@highlandtechnology.com> writes:

On Tue, 18 Aug 2015 15:55:30 +0100, John Devereux
john@devereux.me.uk> wrote:


"2-5 times higher thermal conductivity than copper"

It's very anisotropic, with high thermal conductivity only in the
plane of a sheet. That makes it useless for most electronic
applications.

I suspected that - they did illustrate it as a sort of flex-circuit heat
pipe sort of thing.

I have not heard much about this wonder material, is it actually any use
for anything?

https://en.wikipedia.org/wiki/Pyrolytic_carbon#Applications

--

John Devereux

 

[Phil Hobbs]

On 08/18/2015 10:55 AM, John Devereux wrote:

"2-5 times higher thermal conductivity than copper"

I have not heard much about this wonder material, is it actually any use
for anything?

It's diamagnetic enough that you can levitate it over a quadrupole made
of permanent magnets. The more physics somebody knows, the bigger the
double-take they do when you show them.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net

 

[Tim Williams]

I think I had calculated that it's 7 times worse in specific conductivity
per price. So, if you *really* need that extra couple C/W shaved off your
thermal spec (like, perhaps, some hapless engineer tasked with designing a
Macbook in a titanium skin?...), and literally cannot spare another two
thousandths of an inch clearance... maybe you'll spring for it.

For everything else, heck... a multilayer PCB outperforms any commercially
available thickness of the stuff. So the list of situations where it's
useful must be terribly small.

Through-plane conductivity doesn't matter much, since you'll mostly be
sticking it to wide areas which will therefore have much higher cross
section. (Same is true of PCBs, incidentally, which is why it's so
beneficial to use thermal vias.)

I suppose it would tend to be somewhat EMI dissipative, so there's that,
too. Speaking of, note it's conductive, so you can't just wrap your PCBs
with it, anyway. An adhesive or film backed product is therefore even
worse, thermally.

Tim

--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Contract Design
Website: http://seventransistorlabs.com


"John Devereux" wrote in message news:87pp2ky7bx.fsf@devereux.me.uk...


"2-5 times higher thermal conductivity than copper"

I have not heard much about this wonder material, is it actually any use
for anything?


--

John Devereux

 

[Lasse Langwadt Christense]

Den onsdag den 19. august 2015 kl. 16.22.49 UTC+2 skrev John Larkin:

On Tue, 18 Aug 2015 22:46:07 -0700 (PDT), edward.ming.lee@gmail.com
wrote:

On Tuesday, August 18, 2015 at 9:06:26 PM UTC-7, John Larkin wrote:
On Tue, 18 Aug 2015 20:02:02 -0700, Robert Baer
robertbaer@localnet.com> wrote:

John Larkin wrote:
On Tue, 18 Aug 2015 15:55:30 +0100, John Devereux
john@devereux.me.uk> wrote:


"2-5 times higher thermal conductivity than copper"

It's very anisotropic, with high thermal conductivity only in the
plane of a sheet. That makes it useless for most electronic
applications.

* Don't you have_any_ imagination?

Not enough to do dumb things.


Use that property to carry heat AWAY from a pesky source..(not too
hard to solve thermal coupling on both ends).

Check out the pricing for small, thin pieces of the stuff:

http://www.digikey.com/product-search/en?keywords=Pyrolytic

That would be insane as a heat spreader. Aluminum or copper make way
more sense.

Actually, the 90x60 is reasonably priced at $3.29.

Nice for floating above magnets, but it's as thick as a sheet of
paper, not much use as a heat spreader.

it doesn't need to be thick to transfer heat

https://youtu.be/R5dwdZCKBZM


-Lasse

 

[John Larkin]

On Tue, 18 Aug 2015 22:46:07 -0700 (PDT), edward.ming.lee@gmail.com
wrote:

On Tuesday, August 18, 2015 at 9:06:26 PM UTC-7, John Larkin wrote:
On Tue, 18 Aug 2015 20:02:02 -0700, Robert Baer
robertbaer@localnet.com> wrote:

John Larkin wrote:
On Tue, 18 Aug 2015 15:55:30 +0100, John Devereux
john@devereux.me.uk> wrote:


"2-5 times higher thermal conductivity than copper"

It's very anisotropic, with high thermal conductivity only in the
plane of a sheet. That makes it useless for most electronic
applications.

* Don't you have_any_ imagination?

Not enough to do dumb things.


Use that property to carry heat AWAY from a pesky source..(not too
hard to solve thermal coupling on both ends).

Check out the pricing for small, thin pieces of the stuff:

http://www.digikey.com/product-search/en?keywords=Pyrolytic

That would be insane as a heat spreader. Aluminum or copper make way
more sense.

Actually, the 90x60 is reasonably priced at $3.29.

Nice for floating above magnets, but it's as thick as a sheet of
paper, not much use as a heat spreader.




--

John Larkin Highland Technology, Inc
lunatic fringe electronics

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[John Larkin]

On Wed, 19 Aug 2015 09:16:55 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

Den onsdag den 19. august 2015 kl. 16.22.49 UTC+2 skrev John Larkin:
On Tue, 18 Aug 2015 22:46:07 -0700 (PDT), edward.ming.lee@gmail.com
wrote:

On Tuesday, August 18, 2015 at 9:06:26 PM UTC-7, John Larkin wrote:
On Tue, 18 Aug 2015 20:02:02 -0700, Robert Baer
robertbaer@localnet.com> wrote:

John Larkin wrote:
On Tue, 18 Aug 2015 15:55:30 +0100, John Devereux
john@devereux.me.uk> wrote:


"2-5 times higher thermal conductivity than copper"

It's very anisotropic, with high thermal conductivity only in the
plane of a sheet. That makes it useless for most electronic
applications.

* Don't you have_any_ imagination?

Not enough to do dumb things.


Use that property to carry heat AWAY from a pesky source..(not too
hard to solve thermal coupling on both ends).

Check out the pricing for small, thin pieces of the stuff:

http://www.digikey.com/product-search/en?keywords=Pyrolytic

That would be insane as a heat spreader. Aluminum or copper make way
more sense.

Actually, the 90x60 is reasonably priced at $3.29.

Nice for floating above magnets, but it's as thick as a sheet of
paper, not much use as a heat spreader.


it doesn't need to be thick to transfer heat

https://youtu.be/R5dwdZCKBZM

Theta goes as 1/thickness. So it depends on how much heat you want to
spread.

A piece of 0.062" thick aluminum would be a better (and rigid!) heat
spreader and cost a fraction of that graphite thing. Z-axis heat
conduction helps in most practical spreader applications, so the
aluminum thickness is good.

How are you going to bolt a transistor to that flimsy thin graphite
thing?


--

John Larkin Highland Technology, Inc
lunatic fringe electronics

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[Kevin McMurtrie]

In article <1749ta5a81f0r4vaglas487iiijvk3lahc@4ax.com>,
John Larkin <jlarkin@highlandtechnology.com> wrote:

On Tue, 18 Aug 2015 22:46:07 -0700 (PDT), edward.ming.lee@gmail.com
wrote:

On Tuesday, August 18, 2015 at 9:06:26 PM UTC-7, John Larkin wrote:
On Tue, 18 Aug 2015 20:02:02 -0700, Robert Baer
robertbaer@localnet.com> wrote:

John Larkin wrote:
On Tue, 18 Aug 2015 15:55:30 +0100, John Devereux
john@devereux.me.uk> wrote:


"2-5 times higher thermal conductivity than copper"

It's very anisotropic, with high thermal conductivity only in the
plane of a sheet. That makes it useless for most electronic
applications.

* Don't you have_any_ imagination?

Not enough to do dumb things.


Use that property to carry heat AWAY from a pesky source..(not too
hard to solve thermal coupling on both ends).

Check out the pricing for small, thin pieces of the stuff:

http://www.digikey.com/product-search/en?keywords=Pyrolytic

That would be insane as a heat spreader. Aluminum or copper make way
more sense.

Actually, the 90x60 is reasonably priced at $3.29.

Nice for floating above magnets, but it's as thick as a sheet of
paper, not much use as a heat spreader.

It conducts better than you'd think and it can conform to uneven
surfaces better than copper.

--
I will not see posts from astraweb, theremailer, dizum, or google
because they host Usenet flooders.

 

On Wednesday, August 19, 2015 at 9:15:07 PM UTC-7, Kevin McMurtrie wrote:

In article <1749ta5a81f0r4vaglas487iiijvk3lahc@4ax.com>,
John Larkin <jlarkin@highlandtechnology.com> wrote:

On Tue, 18 Aug 2015 22:46:07 -0700 (PDT), edward.ming.lee@gmail.com
wrote:

On Tuesday, August 18, 2015 at 9:06:26 PM UTC-7, John Larkin wrote:
On Tue, 18 Aug 2015 20:02:02 -0700, Robert Baer
robertbaer@localnet.com> wrote:

John Larkin wrote:
On Tue, 18 Aug 2015 15:55:30 +0100, John Devereux
john@devereux.me.uk> wrote:


"2-5 times higher thermal conductivity than copper"

It's very anisotropic, with high thermal conductivity only in the
plane of a sheet. That makes it useless for most electronic
applications.

* Don't you have_any_ imagination?

Not enough to do dumb things.


Use that property to carry heat AWAY from a pesky source..(not too
hard to solve thermal coupling on both ends).

Check out the pricing for small, thin pieces of the stuff:

http://www.digikey.com/product-search/en?keywords=Pyrolytic

That would be insane as a heat spreader. Aluminum or copper make way
more sense.

Actually, the 90x60 is reasonably priced at $3.29.

Nice for floating above magnets, but it's as thick as a sheet of
paper, not much use as a heat spreader.

It conducts better than you'd think and it can conform to uneven
surfaces better than copper.

And lighter too. However, pure PG could peel off like skins. We can perhaps dope it with impurity for stronger z-bond, but lower x,y conductivity. I.e. semi-thermo-conductor.

Problem is how to build the CVD chamber. Almost everything else (metal, glass) would melt before reacting 2400K.

 

[John Larkin]

On Wed, 19 Aug 2015 21:09:30 -0700, Kevin McMurtrie
<mcmurtrie@pixelmemory.us> wrote:

In article <1749ta5a81f0r4vaglas487iiijvk3lahc@4ax.com>,
John Larkin <jlarkin@highlandtechnology.com> wrote:

On Tue, 18 Aug 2015 22:46:07 -0700 (PDT), edward.ming.lee@gmail.com
wrote:

On Tuesday, August 18, 2015 at 9:06:26 PM UTC-7, John Larkin wrote:
On Tue, 18 Aug 2015 20:02:02 -0700, Robert Baer
robertbaer@localnet.com> wrote:

John Larkin wrote:
On Tue, 18 Aug 2015 15:55:30 +0100, John Devereux
john@devereux.me.uk> wrote:


"2-5 times higher thermal conductivity than copper"

It's very anisotropic, with high thermal conductivity only in the
plane of a sheet. That makes it useless for most electronic
applications.

* Don't you have_any_ imagination?

Not enough to do dumb things.


Use that property to carry heat AWAY from a pesky source..(not too
hard to solve thermal coupling on both ends).

Check out the pricing for small, thin pieces of the stuff:

http://www.digikey.com/product-search/en?keywords=Pyrolytic

That would be insane as a heat spreader. Aluminum or copper make way
more sense.

Actually, the 90x60 is reasonably priced at $3.29.

Nice for floating above magnets, but it's as thick as a sheet of
paper, not much use as a heat spreader.

It conducts better than you'd think and it can conform to uneven
surfaces better than copper.

You've still got to do the numbers. If the p.g. conducts heat 5x
better than aluminum, but the aluminum is 20x thicker, the cheap
aluminum wins.

"Conforming" is a mixed blessing. To conduct heat, you need an
intimate contact with the thing to be cooled and with the place to
dump the heat. That implies adhesives or something to get the flexy
p.g. to stick to a chip or whatever, and an adhesive will wreck the
thermal conductivity.


--

John Larkin Highland Technology, Inc
lunatic fringe electronics

jlarkin att highlandtechnology dott com
http://www.highlandtechnology.com

 

[whit3rd]

On Thursday, August 20, 2015 at 9:04:41 AM UTC-7, John Larkin wrote:

On Wed, 19 Aug 2015 21:09:30 -0700, Kevin McMurtrie
mcmurtrie@pixelmemory.us> wrote:

It conducts better than you'd think and it can conform to uneven
surfaces better than copper.

You've still got to do the numbers...

"Conforming" is a mixed blessing. To conduct heat, you need an
intimate contact with the thing to be cooled and with the place to
dump the heat. That implies adhesives or something to get the flexy
p.g. to stick to a chip or whatever, and an adhesive will wreck the
thermal conductivity.

That's bad analysis of the mixed blessing. Conforming means the material
can be pressed into the shape of the object, and a film of adhesive
is a small thermal resistance in series. A much thinner film of adhesive
is a MUCH SMALLER thermal resistance in series. Conforming and non-void-filling
adhesives work together to improve the heatsinking. Because the
graphite is electrically conductive, it would be applied to the epoxy of
your packages, not the leadwires: it's the epoxy you should worry about,
as far as thermal resistance goes.

 

[John Larkin]

On Thu, 20 Aug 2015 15:14:47 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:

On Thursday, August 20, 2015 at 9:04:41 AM UTC-7, John Larkin wrote:
On Wed, 19 Aug 2015 21:09:30 -0700, Kevin McMurtrie
mcmurtrie@pixelmemory.us> wrote:

It conducts better than you'd think and it can conform to uneven
surfaces better than copper.

You've still got to do the numbers...

"Conforming" is a mixed blessing. To conduct heat, you need an
intimate contact with the thing to be cooled and with the place to
dump the heat. That implies adhesives or something to get the flexy
p.g. to stick to a chip or whatever, and an adhesive will wreck the
thermal conductivity.

That's bad analysis of the mixed blessing. Conforming means the material
can be pressed into the shape of the object, and a film of adhesive
is a small thermal resistance in series. A much thinner film of adhesive
is a MUCH SMALLER thermal resistance in series. Conforming and non-void-filling
adhesives work together to improve the heatsinking. Because the
graphite is electrically conductive, it would be applied to the epoxy of
your packages, not the leadwires: it's the epoxy you should worry about,
as far as thermal resistance goes.

Do you use this stuff? Got any pix?