Re: Heatsinking a power component

On Jul 7, 7:43 pm, John Larkin
<jjlar...@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
On Tue, 7 Jul 2009 16:35:16 -0500, "Tim Williams"

<tmoran...@xxxxxxxxxxx> wrote:
I recall Larkin's been soldering copper flags on things for this purpose..

That was an act of desperation!



You know those spherical diodes you often see soldered to heatsinks?  Get
some of those heatsinks.  They're either tin plated steel or copper,
obviously not aluminum since they're solderable.  Find a convienient
mounting combination (through hole / surface mount?) and go with that.
Bonus points if you come up with a useful product that Digikey wants to
stock.  ;-)

Tim

We're designing a gadget now that uses a power opamp in a 7-pin DPAK
sort of package. It will dissipate about 2 watts max, so we're using a
surface-mount heat sink which straddles the opamp, plus a lot of
copper in thermal contact with the chip base, topside, and with
thermal vias to more copper on the bottom.

http://www.aavidthermalloy.com/cgi-bin/stdisp.pl?Pnum=7106dg

But I'd be reluctant to try to get tens of watts out of any dpak type
of part. The thermal resistance of 1 oz copper foil is about 70K/w per
square, so you've almost lost the battle before you get to the heat
sink.

John

Thanks to everybody... I mentioned only tip of the iceberg. The hot
part is IRFS3206. I have proto PCB designed for D2PAK and MOSFETS were
blowing up until I kludged up TO220 package with the heat sink there
(I made TO220 packages out of D2PAK before ordering right part)
After some search and comparison I figured out that Infineon
IPB030N08N3 G and especially BSC028N06LS3 G should run much cooler (I
hope that they do meet the specs, there is no other way to find out
but try them). The parts come in SMT package only. My plan is to make
a PCB with the hole for the Cu or Al slug (attached to the heat sink
on the opposite side of the PCB) pressed against the tab. I do not
visualize it clearly yet, but, hey, I am an EE with the whiteboard/
eraser combo for mechanical design tool. Some pictures of existing
designs might help.
Somebody mentioned that laptop people do it all the time. Sounds
interesting, but I do not have a laptop that I can pry open. :o(
.

Relevant Pages

  • Re: Heatsinking a power component
    ...  They're either tin plated steel or copper, ... blowing up until I kludged up TO220 package with the heat sink there ... assuming 1 oz thru-hole plating and no solder inside. ...
    (sci.electronics.design)
  • Re: Heatsinking a power component
    ... They're either tin plated steel or copper, ... thermal vias to more copper on the bottom. ... blowing up until I kludged up TO220 package with the heat sink there ... near the rim of the pour, ...
    (sci.electronics.design)
  • Re: Heatsinking a power component
    ... They're either tin plated steel or copper, ... But I'd be reluctant to try to get tens of watts out of any dpak type ... blowing up until I kludged up TO220 package with the heat sink there ... near the rim of the pour, ...
    (sci.electronics.design)
  • Re: Heatsinking a power component
    ...  They're either tin plated steel or copper, ... thermal vias to more copper on the bottom. ... blowing up until I kludged up TO220 package with the heat sink there ... near the rim of the pour, ...
    (sci.electronics.design)
  • Re: Heatsinking a power component
    ...  They're either tin plated steel or copper, ... thermal vias to more copper on the bottom. ... blowing up until I kludged up TO220 package with the heat sink there ... near the rim of the pour, ...
    (sci.electronics.design)