On Tue, Aug 28, 2001 at 08:54:46AM -0500, Eisermann, Phil [Ridg/CO] wrote:
>         That would be the way to go. Lots of distributors sell mounting kits
> for power transistors, which generally include the insulator. Check for
> example DigiKey, Mouser, Jameco.
>
>         If you can't use the existing metal, another way to go is an
> aluminum channel underneath the board (assuming TO-220 or somesuch). Mount
> the transistors on the bottom of the board, at a 90 degree angle so the
> metal portion of the case makes contact with the aluminum. Crude ascii art
> to illustrate concept:
>
>           (board) ----------------
>      (transistor)    *****
>       (heatsink)  ================

Outstanding idea. I couple even mount the sink perpendicular to the board
and have the transistors out on the edge.

Thanks for the info...

BAJ

>
> In other words, you're sandwitching the transistor between the board and
> heatsink. By mounting the transistors on the bottom, you don't have to worry
> about interference with large caps and connectors. You can also buy finned
> heatsink material and cut that to size; but I find plain aluminum channel
> stock is cheaper, has a reasonably smooth surface finish, and works well in
> most cases. You can probably get the channel stock through Grainger or
> McMaster. You can make the heatsink as big/long as your board without adding
> a lot of height.
>
>
> > -----Original Message-----
> > From: John Walshe [mailto:John.Walshe@INPACTMICRO.COM]
> > Sent: Tuesday, August 28, 2001 9:28 AM
> > To: PICLIST@MITVMA.MIT.EDU
> > Subject: Re: [OT]: How to heatsink a lot of power electronics?
> >
> >
> > Why don't you make use of all of that metal in the drive
> > path? Assuming the
> > FETs/Transistors are isolated devices the metal framework
> > should provide a
> > reasonable heatsink, without too much trouble. If the above
> > are not isolated
> > devices then you will have to put a mica strip(or modern
> > equivalent) between
> > the device and the metal.
> > John
> >
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