TO247 mounting

[Mathieu thm]

Hello, I will show you a tip to mount IGBTs in TO247 package to perform better heat dissipation.

If the IGBT mounting screw is used with an insulating pad, the IGBT may crush the pad at the screw and lift the other side of the IGBT (where there is the die), and the heat transfer is not good.
The main idea is to apply pressure just above the IGBT die for better heat dissipation.

I made metal tabs from this piece of metal, the next pictures are enough to understand without comment :

[Weston]

Looks like a cool idea! I have seen some similar clips in commercial products.

One thing I would be worried about is the compliance of the strap you are using, if its not springy it might just deform under load and not have much clamping force, especially after a few thermal cycles. A spring washer might help.

Luckily it does not require too much clamping force, it just has to be in the right place. A M3 screw tightened to the suggested torque provides ~200+ PSI of force on the area of the thermal pad and can warp the package, as you mentioned. But you really only need 25 - 50PSI on most thermal pads to get the minimum thermal resistance.

[davekni]

Looks like a cool idea! I have seen some similar clips in commercial products.

One thing I would be worried about is the compliance of the strap you are using, if its not springy it might just deform under load and not have much clamping force, especially after a few thermal cycles. A spring washer might help.

Yes, nice implementation.  Much better than just a screw for mounting even without much springiness.  A spring washer under the screw head is a great addition.