heat sink attaching

[David Lesher]

I need to add a heatsink to a small product. It has a flat exposed flush
heatsink now; I'm extending with fins.

But the attachment is an issue. Do the pads you put between a CPU & heatsink
provide any stick? Or are the depending on external pressure to compress
them? [I have no way to do that...]

For the record, this is a Mobius camera.
<http://www.techmoan.com/blog/2013/7...e-do-it-all-mount-anywhere-1080p-micro-c.html>

 

[gregz]

I need to add a heatsink to a small product. It has a flat exposed flush
heatsink now; I'm extending with fins.

But the attachment is an issue. Do the pads you put between a CPU & heatsink
provide any stick? Or are the depending on external pressure to compress
them? [I have no way to do that...]

For the record, this is a Mobius camera.
<http://www.techmoan.com/blog/2013/7...e-do-it-all-mount-anywhere-1080p-micro-c.html>

What do you want to do, and why ?

Temporary or permanent ?

Pads don't usually have optimum heat transfer. Metal to metal contact is
optimum, unless surfaces are really off.

Does the camera instructions say, add heat sink ?

Greg

 

[Charlie+]

I need to add a heatsink to a small product. It has a flat exposed flush
heatsink now; I'm extending with fins.

But the attachment is an issue. Do the pads you put between a CPU & heatsink
provide any stick? Or are the depending on external pressure to compress
them? [I have no way to do that...]

For the record, this is a Mobius camera.
<http://www.techmoan.com/blog/2013/7...e-do-it-all-mount-anywhere-1080p-micro-c.html>

Pads normally require mechanical pressure permanently.
You can use epoxy resin as long as the layer is thin and you prepare the
surfaces for mechanical key. Used this method on componants running
too hot to last! Fast set epoxy is better because it never quite seems
to set as rock solid as slow cure and thus shouldnt shatter under shock.
C+

 

[Phil Allison]

"David Lesher"

I need to add a heatsink to a small product. It has a flat exposed flush
heatsink now; I'm extending with fins.

But the attachment is an issue.

** Suggest you lightly sand the mating surfaces with fine emery paper and
then smear with "super glue".

Hold together tightly for several minutes.

Should be reasonably strong.



..... Phil

 

[Phil Allison]

"isw"

In fact, because the pads are a lot easier to apply properly than
grease, the pads usually perform a bit better.

** The opposite is true.

1. Pads vary enormously in their performance - the cheapest are silicone
rubber and are shit awful at conducting heat.

2. Nothing beats two smooth, mating metal surfaces with a smear of compound
between.

3. Next best is thin mica insulation (1 or 2 thou of an inch ) with a smear
of compound each side.

Even pressure is crucial to getting good thermal transfer, the usual bolt in
the top part of a TO220 or TO3P metal tab is a horrible way.


.... Phil

 

[David Lesher]

What do you want to do, and why ?

Temporary or permanent ?

The camera has a reputation for running hot. In fairness, the
original market was RC aircraft where forced air cooling is
readily available. Other non-RC users have added heatsinks.



I studied the thermal conductivity issue a few years ago; I was
coupling sensors to copper pipes & comparing approaches. What
I found was any of the pastes & conductive epoxies I found had
thermal resistances so high, vice metal-to-metal, they looked
useful only against air gaps. In other words, they help by not
being air, but lapping is a far better solution.