Thermal Management — Wolfspeed Power Applications Forum

[FAQ-THERM-4] How can I mount TO-247 devices on the heatsink to get good thermal performance?

TBhatia — Tue, 01 Nov 2022 22:47:10 +0000

There are some design considerations when designing the thermal management system for Through-Hole devices. For the details on the choice of device, mounting technique and Thermal Interface Material (TIM) please refer to the Application Note "THERMAL MEASUREMENT AND DESIGN RECOMMENDATIONS FOR WOLFSPEED® SIC POWER DEVICES IN TO-247 PACKAGE"

[FAQ-THERM-3] Can I directly solder TO-247 body to PCB or heatsink like surface mount devices?

TBhatia — Tue, 01 Nov 2022 22:34:06 +0000

No. Usually there is a MSL (Moisture Sensitivity Level) rating for surface mount device to define the condition of the device before it is soldered to PCB. There is no MSL rating defined for TO-247 devices.

[FAQ-THERM-2] How can I evaluate thermal performance of SiC devices before hardware build?

TBhatia — Tue, 01 Nov 2022 22:28:40 +0000

You can calculate power dissipation of power devices in your converter through calculation or simulation.

The fastest way is to use Wolfspeed online simulation tool Speedfit 2.0 which includes majority of power converter topologies and all of Wolfspeed's SiC device portfolio.

More details on junction temperature calculation using thermal impedance and power loss of the device can be found in this Application Note "Thermal Management of Bottom-Side Cooled Surface Mount Devices and Design Considerations" under design examples.

[FAQ-THERM-1] What are different ways to cool bottom-side cooled surface mount devices?

TBhatia — Tue, 01 Nov 2022 22:11:06 +0000

There are some design considerations when designing the thermal management system of bottom-side cooled SMDs.

For a detailed overview please refer to the Application Note "Thermal Management of Bottom-Side Cooled Surface Mount Devices and Design Considerations" for the choice of device, PCB, Thermal Interface Material (TIM) and heatsink mounting.

For the PCB,

Low power (<3-4kW): Thermal vias in PCB can be used. The Application Note linked above discusses the thermal via pattern and PCB details and the impact it has on the thermal impedance of the PCB.
High power (>4kW): IMS (insulated Metal substrate) or AlN embedded PCB ) or Aluminum Nitride (AlN) ceramics embedded PCB's are recommended. A good reference for use of AlN embedded PCB's can be found in Wolfspeed KIT-CRD-8FF90P