On 02/ 1/11 02:42 AM, Dan Sawyer wrote:
> The project is to mount a 1KW, 2 transistor, board on a heat sink. The
> transistor centers are about 2 inches. The question is: What should the
> dimensions of the heat spreader be? I have seen dimensions of 1/4 x 2 x
> 4 up to 1/2 x 4 x 7; that represents quite a range. The questions are:
> 1. What thickness is required. Is 1/4 sufficient?
> 2. What is the minimum effective distance from the edge of the devices?
> 1/2 inch? 1 inch?
If you can get a free trial of some finite element software for thermal
analysis, this sort of thing would be relatively easy to model. You could then
see the effects of changing the thickness and length/width.
ANSYS is one bit of software I suspect could help with this. You can probably
get a trial.
You might find heat sink manufacturers could suggest solutions.
I would think it quite difficult to guess this sort of thing, unless you have a
lot of experience in the field. That's probably why you see widely different
My guess is there are diminishing returns for making this thicker and larger.
But where those points are would be very difficult to calculate using anything
other than finite element or finite difference software.
I suspect you can make the copper too thick too. If very thick, the convection
on the heatsink will be less effective.
I can't believe this is rocket science, but I don't think it would be easy to
determine by any method other than trying lots of different sizes/shapes
(expensive) or computer modeling (cheap and relatively easy).
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