Thermal Resistance RthCH

luke13

Hello Wolfspeed Technicians,

my company bought a CRD200DA12E-XM3 inverter and I want to calculate the maximum junction temperature for the application.

I already got the values for the RthJC and the RthHF (Heatsink to Coolant).

Now I was wondering abouth the thermal resistance between the case and the heatsink. My approach was to take the area of a CAB400M12XM3 and the thickness of 6 mil from the CPWR-AN29 and calculate the resistance with the GreyIce 4060 TIM ( 6 W/(m*K) ).

Resulting in a thermal resistance of 0.006 K/W.

Does the value make sense?

Thanks for your suggestions.

Best regards Lukas

Forum_Moderator

Thank you for your post, it has been approved and we will respond as soon as possible.

ShamarChristian

Hello Lukas,

Estimating the thermal resistance from the case to the heatsink (the thermal interface layer) is difficult to perform via calculations, and even simulations due to surface texture, warp and other related boundary conditions.

We recommend deriving this value from a direct observation/measurement of RthJF. By doing this, the properties of the interfacial layer will be reflected in the thermal resistance stack. This should be sufficient to estimate maximum junction temperature.

luke13

Okay, thanks for your help.