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MOSFET (Si/SiC) Forum Discussions

User21259
Level 1
First question asked First reply posted
Level 1
Hi everyone,

I'm using F4-23MR12W1M1P_B11 power module in my projet and i'm looking for a heatsink to use with, does anyone have any recommandations ?

Thank you
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1 Solution
Pablo_EG
Moderator
Moderator 250 sign-ins 250 replies posted 25 likes received
Moderator
Hello Hamza,

When choosing a heatsink, there are a number of parameters that should be taken into account.
I will use section 7.5 of the following app note as a reference to answer your query. Please refer to it if my explanation is not clear:
https://www.infineon.com/dgdl/Infineon-AN2018-13_CIPOS_IM393-XX-AN-v01_00-EN.pdf?fileId=5546d46269e1...

However, if the transient state is not to be taken into account, the required heatsink specs can be extracted using an equivalent circuit.
5120.attach

Here we can ignore the capacitors, as we are only interested in the steady-state performance.
Each resistance is the equivalent of the thermal resistance of one part of the system.
Rth1 being the thermal resistance between the junction and case, Rth2 being the TIM (thermal interface material) resistance, Rth3 being the heatsink's resistance and lastly, Rth4 is the convection to ambient.

The square on the left represents the temperature of the junction and the one on the right represents the ambient temperature.
The "current" flowing through the equivalent circuit would be the power loss of the module.
Thus, the equation for the thermal network is:

T_j - T_amb = Ploss_max * (Rth1+Rth2+Rth3+Rth4)

We need to remember that we are designing it for the worst case, this is why we use the maximum power loss of the system.
Most devices should not exceed 125 degrees celsius, so T_j can be set as 125 (or 100 for a strong safety margin).
Ambient temperature should be set to whatever maximum temperature the air around the module will be at. (If the module is inside a case, we have to take into account the rise in temperature).

In your case, looking at the datasheet, the junction to case resistance of the module seems to be 0.9 K/W, which includes the pre-applied thermal interface (that is Rth1 and Rth2).
Lastly, the maximum power loss for your application is required. You should calculate it including both conduction and switching losses.

With this, your heatsink should have a thermal resistance of at least = (T_j - T_amb - 0.9*Ploss_max)
That includes the heatsink's resistance as well as the convection to ambient resistance. Many heatsink makers provide those two as one parameter.

The heatsink should cover all of the baseplate surface.

For further instruction, please refer to the app note.

Let me know if you have any more questions.


Pablo

View solution in original post

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3 Replies
Pablo_EG
Moderator
Moderator 250 sign-ins 250 replies posted 25 likes received
Moderator
Hello Hamza,

When choosing a heatsink, there are a number of parameters that should be taken into account.
I will use section 7.5 of the following app note as a reference to answer your query. Please refer to it if my explanation is not clear:
https://www.infineon.com/dgdl/Infineon-AN2018-13_CIPOS_IM393-XX-AN-v01_00-EN.pdf?fileId=5546d46269e1...

However, if the transient state is not to be taken into account, the required heatsink specs can be extracted using an equivalent circuit.
5120.attach

Here we can ignore the capacitors, as we are only interested in the steady-state performance.
Each resistance is the equivalent of the thermal resistance of one part of the system.
Rth1 being the thermal resistance between the junction and case, Rth2 being the TIM (thermal interface material) resistance, Rth3 being the heatsink's resistance and lastly, Rth4 is the convection to ambient.

The square on the left represents the temperature of the junction and the one on the right represents the ambient temperature.
The "current" flowing through the equivalent circuit would be the power loss of the module.
Thus, the equation for the thermal network is:

T_j - T_amb = Ploss_max * (Rth1+Rth2+Rth3+Rth4)

We need to remember that we are designing it for the worst case, this is why we use the maximum power loss of the system.
Most devices should not exceed 125 degrees celsius, so T_j can be set as 125 (or 100 for a strong safety margin).
Ambient temperature should be set to whatever maximum temperature the air around the module will be at. (If the module is inside a case, we have to take into account the rise in temperature).

In your case, looking at the datasheet, the junction to case resistance of the module seems to be 0.9 K/W, which includes the pre-applied thermal interface (that is Rth1 and Rth2).
Lastly, the maximum power loss for your application is required. You should calculate it including both conduction and switching losses.

With this, your heatsink should have a thermal resistance of at least = (T_j - T_amb - 0.9*Ploss_max)
That includes the heatsink's resistance as well as the convection to ambient resistance. Many heatsink makers provide those two as one parameter.

The heatsink should cover all of the baseplate surface.

For further instruction, please refer to the app note.

Let me know if you have any more questions.


Pablo
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User21259
Level 1
First question asked First reply posted
Level 1
Hello Pablo,

Thank you for your answer, its really well explained !

But i'm looking for a refernce of a heatsink that matches the F4-23MR12W1M1P_B11 to use in my prototype ?

Thanks again 🙂
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Pablo_EG
Moderator
Moderator 250 sign-ins 250 replies posted 25 likes received
Moderator
Hello Hamza,

Unfortunately, I cannot recommend any particular brand or model for the heat sink.
I understand that finding the correct one might be difficult.
There is no standard heatsink type that is intended for your module, so you will have to be guided by the dimensions of the backplate.
This module is mostly used with custom heat sinks.
I attach an app note which gives you the dimension details for your specific module, and how to successfully mount it.

https://www.infineon.com/dgdl/Infineon-AN2006_08_Mounting_Instructions_EasyB_Series-ApplicationNotes...

I understand that this is not the answer that you were hoping for, but this is as much as I can do.
Let me know if you can identify a model which suits your dimensions.

Best regards,
Pablo
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