Heatsing for TO263

P

Piotr Wyderski

Guest
Hi,

does this make much sense?

http://smartheatsinks.com/SHS_SMT.pdf

The heat path between the transistor and the heatsink is awkward.

Best regards, Piotr
 
On 2020-04-19 04:18, Piotr Wyderski wrote:
Hi,

does this make much sense?

http://smartheatsinks.com/SHS_SMT.pdf

The heat path between the transistor and the heatsink is awkward.

    Best regards, Piotr
Click to expand...

Reduces the board area required for thermal pours, and will work
slightly better. Their claims about better thermal performance look
like snake oil--theta will be dominated by the copper pour.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com
 
On Sun, 19 Apr 2020 10:18:56 +0200, Piotr Wyderski
<peter.pan@neverland.mil> wrote:

Hi,

does this make much sense?

http://smartheatsinks.com/SHS_SMT.pdf

The heat path between the transistor and the heatsink is awkward.

Best regards, Piotr
Click to expand...

Look at the competition - same issue.

The AAVID parts are tinned copper and patented up
the wazzoo.

It would likely make more sense to turn the TO220 around, fix
it to the extrusion, and then reflow the extrusion to the board.

...but then it wouldn't be a refow-only assembly.

Fabs are allergic to mechanical fasteners.

RL
 
On Sun, 19 Apr 2020 10:18:56 +0200, Piotr Wyderski
<peter.pan@neverland.mil> wrote:

Hi,

does this make much sense?

http://smartheatsinks.com/SHS_SMT.pdf

The heat path between the transistor and the heatsink is awkward.

Best regards, Piotr
Click to expand...

We use these,

https://www.dropbox.com/s/klpmvkfswq9tzmb/Surf_Mount_Heatsink.jpg?raw=1

similar idea. You need a topside copper pour to transfer heat from the
dpak tab to the heat sink. That might be in the ballpark of 5 K/w, so
adds to the overall theta some.

What do those things cost? The hype level on the data sheet is high.
There is no data below 200 fpm air flow, and the theta numbers look
optimistic. All those tiny fins are useless at low air flow. The digs
at Aavid are absurd.

You can get pretty good dpak cooling by coupling through vias into pcb
planes, and that's free.



--

John Larkin Highland Technology, Inc

Science teaches us to doubt.

Claude Bernard
 
legg wrote...
It would likely make more sense to turn the TO220 around,
fix it to the extrusion, and then reflow the extrusion
to the board.

..but then it wouldn't be a refow-only assembly.
Fabs are allergic to mechanical fasteners.
Click to expand...

Yes, good idea. One idea, leave a bit of final
hand work, for after the automated assembly step.


--
Thanks,
- Win
 
On 2020-04-19, legg <legg@nospam.magma.ca> wrote:
On Sun, 19 Apr 2020 10:18:56 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

Hi,

does this make much sense?

http://smartheatsinks.com/SHS_SMT.pdf

The heat path between the transistor and the heatsink is awkward.

Best regards, Piotr

Look at the competition - same issue.

The AAVID parts are tinned copper and patented up
the wazzoo.

It would likely make more sense to turn the TO220 around, fix
it to the extrusion, and then reflow the extrusion to the board.

..but then it wouldn't be a refow-only assembly.
Click to expand...

form the leads for inverted surace mount
reflow the TO220 onto the heatsink.
reflow the assembly onto the board.

or place the TO220, place extra paste on the tab
place the heatsink on the tab.

> Fabs are allergic to mechanical fasteners.

not needed

the problem is getting DPAK with the leads bent away from the tab


This non-isolated buck module places the beastink at the other end
of a bunch of vias: https://www.aliexpress.com/item/32811528144.html
But it's only stuck on with glue (feels like some sort of silicone).

--
Jasen.
 
On Sunday, April 19, 2020 at 10:19:02 AM UTC+2, Piotr Wyderski wrote:
Hi,

does this make much sense?

http://smartheatsinks.com/SHS_SMT.pdf

The heat path between the transistor and the heatsink is awkward.

It looks interesting
Click to expand...

I would perhaps be a little worried about if the heatsink reaches the correct temperature to enable correct soldering of both the heatsink and the SMD device

Cheers

Klaus
 
jlarkin@highlandsniptechnology.com wrote:
On Sun, 19 Apr 2020 10:18:56 +0200, Piotr Wyderski
peter.pan@neverland.mil> wrote:

Hi,

does this make much sense?

http://smartheatsinks.com/SHS_SMT.pdf

The heat path between the transistor and the heatsink is awkward.

Best regards, Piotr


We use these,

https://www.dropbox.com/s/klpmvkfswq9tzmb/Surf_Mount_Heatsink.jpg?raw=1
* Woah! Will it take off and fly?
Click to expand...

similar idea. You need a topside copper pour to transfer heat from the
dpak tab to the heat sink. That might be in the ballpark of 5 K/w, so
adds to the overall theta some.

What do those things cost? The hype level on the data sheet is high.
There is no data below 200 fpm air flow, and the theta numbers look
optimistic. All those tiny fins are useless at low air flow. The digs
at Aavid are absurd.

You can get pretty good dpak cooling by coupling through vias into pcb
planes, and that's free.
Click to expand...
 
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