Do you use Infineons DDPAK (PG-HDSOP-10-1) packaged mosfets or similar ?

[Miyuki]

Hi,

I want to ask if you have an experience with this new top side cooled smd devices
It looks interesting for layout and with reasonable easy cooling
What thermal interface do you use ?

[jbb]

I've been interested to see all the new top-side cooling SMD packages coming out.  Unfortunately the various manufacturers can't seem to agree on a standard (could someone at JEDEC send help??)...

I haven't used them myself, but here are some unfounded opinions helpful suggestions:

• Kelvin source connections are great. Use them
• Do Infineon have an app note or reference design?
• Thermal pads are likely electrically connected to something (probably drain...).  So a half bridge will have at least one thermal pad flying around with high dV/dt.  Look out for capacitive noise coupling to your heatsink especially if using thin thermal interface
• Devices won't be totally flat after soldering, so thermal interface needs a bit of compliance
• Heatsink clamping must be considered - it'll likely screw onto the PCB, so you can't use high clamping forces

Looks like a Sil-Pad or similar silicone thermal pad will be the way to go.  Maybe you can get a sheet large enough to cover all the devices in one go? And is sticky on one side so you just stick it onto the heatsink and assemble?

Lower thermal resistance is likely achieved by some kind of paste (or liquid which sets to gel) but could be awful to prototype.  A squishy thermal glue compound could also be used to simply glue the heatsink on.

Lowest thermal resistance would likely be immersion in a dielectric liquid (e.g. one of the 3M Novec compounds) but likely a total pain in the arse.

[Miyuki]

Kelvin source I want use as I am choosing between conventional TO247-4 and this new packages
They have an app note and saying normal height mismatch is up to 0.1mm with multiple devices so thermal interface must deal with it
They have recommended 3 ways - solder copper heat spreaders (reflow with paste), soft sil pads with spring clamp or glues/adhesive pads

Also IXYS/Littelfuse have some interesting devices, they mostly have internaly insulated as they make their iso247 or how they call it with internal insulator, and have things like boost legs and so

But I now want to try it on fast PFC > MOS + SiC diode about 150-200kHz and only Infineon look like have these devices now and at very interesting prices
With their gate drivers they have nice portfolio, just little vendor lock, but this is just for prototype/learning purposes so no problem

Just wonder why they dont have 1200V devices in these packages when IXYS have them

[thm_w]

• Thermal pads are likely electrically connected to something (probably drain...).  So a half bridge will have at least one thermal pad flying around with high dV/dt.  Look out for capacitive noise coupling to your heatsink especially if using thin thermal interface

Good point. Searched through the datasheet and nothing, they don't even specify..

This page would indicate its connected to some pin: https://www.infineon.com/dgdl/Infineon-Board+Assembly+Recommendations-Gullwing-Package-v04_00-EN.pdf?fileId=5546d4626d82c047016d8c0320de42d0