Random thoughts:
- Go to Home Depot or Lowes and see what ideas you can come up with. I'm not suggesting you buy something there, although you could, just look for ideas.
- Does the case have to be sealed? Maybe ventilation would help.
- If the heatsink in that spot is too hot, what would happen if you drilled out that spot? Would the hot spot spread out to other parts of the heatsink and so, reduce the peak temperature?
- Similar to above, could you make the heatsink thicker so it would spread the heat better.
Ed
Thanks Ed. I like your Hope Depot idea. I bought some fireproof fiber-paper a while back to try to block radiant heat from one component to another...I think benefit was small.
Yes the case has to be sealed, mainly from a safety perspective, but also to meet IP rating. Interesting idea about the drilling. The hot spot is caused by the PFC inductor directly underneath. My intuition says "less heatsink material means the heatsink gets hotter
somewhere" but, your guess is as good as mine.
We designed this new product around an older platform with all heatsink tooling complete. So, unfortunately that's basically set in stone.
Thanks for your suggestions.
Likewise, if you have that much of a hotspot on an Aluminium heatsink inside a closed space, then it's probably not thick enough.
As for thermally insulating foam, you need something that trap sufficient air in cells without being conductive enough to offset the benefit. Not easy in a thin section. You need something as close to aerogel (obviously not practical) as possible. It probably needs to be flame retardant too.
On balance, I think to will be better using some of the space to thicken up the Aluminium and spread the heat more evenly.
P.S. Any chance of changing the heatsink from Aluminium to more thermally conductive copper instead? (I've seen it done in premium quality laptop PSUs).
Thanks for these ideas. I just dremeled out part of the plastic housing to check the actual clearance between housing and the heatsink. Less than I thought. Somewhere between a 0.5-1.0mm air gap. Therefore, as you say, any thermal "insulator" might tend to act more as a conductor in that tiny space.
Thanks for the idea about the copper...This right angle heatsink is actually a "two part" heatsink. That is, two layers of 2.0mm aluminum (but only on the top). Maybe we can change the second layer to copper instead of aluminum. I'd bet that would work.
My "gut feeling" is that adding insulation will only raise the internal temperature and make matters worse...
A band of copper foil on the inside of the plastic box to help spread the heat? Or an aluminum plate glued to the inside of the box, same idea?
Also my gut feeling...hence, why this is my last resort!
We wrapped the whole thing in copper foil and it worked great, from an assembly standpoint, it doesn't fit well. Not enough clearance on the sides in particular. Maybe we can try some 3M 9876 foil, or similar, stuck to the top heatsink.
Thanks all.