Typical RthCH for 62mm modules BM2 & BM3

Petio_Natzkin

Hi Wolfspeed,

what is a typical TIM thermal resistance (RthCH) between the base plate and the heat sink of the 62mm modules (BM2/BM3)?

SiC_Power_Admin

Hi Petio, Our team is looking into your question and will respond shortly.

DanMartin

Hi Petio,

Thank you for your question. The thermal resistance from case to heatsink is highly variable based on the thermal interface material (TIM) utilized along with the particular module under question. Roughly for a 62mm module it can range from 25 % of the module Rjc (for the CAS300M12BM2, CAS300M17BM2, and CAB530M12BM3) to 45% of the module Rjc (for CAS120M12BM2). These numbers are for generic TIM and can be improved with higher performance TIM.

If you have specific condition with specified TIM we can discuss futher. We understand this might be confidential to your application so If you want to, we can continue this conversation through the private message system.

Thanks,

Dan

Fertmann

Hi Dan,

Thanks for your information.

At other Power-Module producer, the Rth(c-s) is sometimes written like this:

| Rth(c-s) | per MOSFET (Lgrease=0.81W/(m+K)) | 0.025 | K/W | (example)

Can you write the Rth(c-s) of the WAB300M12BM3 and CAS300M17BM2 conditional on TIM (W/(m*K)) like above?

Many thanks in advance.

DanMartin

Hello Fertmann,

At present we don't have these numbers. We are looking to add the requested data into the datasheets. We can look at simulation models to get you the data you need if you can share with us the TIM that is planned to be used. Please feel free to reach out to me with the private message feature if that information is sensitive to your application.

Thanks,

Dan

Fertmann

Hi Dan,
At the moment, we use the HTS35SL (“https://res.cloudinary.com/electrolube/images/v1621292101/HTS_248351939a/HTS_248351939a.pdf?_i=AA”) 
and for further Projects, we would like to use the EYGR0611ZLWH (“https://www.mouser.de/datasheet/2/315/AYA0000C50-1129407.pdf”).

Many Thanks!

DanMartin

Hi Fertmann,

Thanks for providing the information. We are going to simulate the thermal resistance based on these materials. This will take several days and we'll get back to you this week.

Thanks,

Dan

DanMartin

Hi Fertmann,

Sorry for the delay. Based on the thermal grease you've specified, we simulate 0.034°C/W for the WAB300M12BM3 and 0.03°C/W for the CAS300M17BM2.

For graphite sheets, we do recommend you evaluate some high performance grease or phase change material. Often times, the achievable bond line thickness with a graphite sheet cannot go low enough to outperform a grease or phase change material.

BR,

Dan

Fertmann

Thanks a lot!

Fertmann

Hi Dan,

Do you have a regarding high performance grease to reach best performance?

Preferably one that is easy to purchase.

Many Thanks!

DanMartin

Hi Fertmann,

You could try https://timtronics.com/wp-content/uploads/2017/12/Grey-Ice-4060_TDS.pdf for a grease. For phase change material, you can look at https://thermalmanagement.honeywell.com/content/dam/thermalmanagement/en/documents/document-lists/technical/PTM6000-ThermalManagement-Datasheet.pdf

Both of these solutions are high thermal conductivity solutions that should help improve heat transfer through the TIM interface.

BR,

Dan

Fertmann

Hi Dan,

Which thermal resistance Rth(c-s) would be reached with the Grey Ice 4060 (for WAB300M12BM3 and CAS300M17BM2)?

Thanks!

DanMartin

Hi Fertmann,

For the WAB300M12BM3 the simulated RCH = 0.0207°C/W and for the CAS300M17BM2 the simulated RCH = 0.0175°C/W with Grey Ice 4060.

BR,

Dan

SiC_Power_Admin

Hi Mr Fertmann ,

I hope that this answered your question. I will close this discussion for now but if you have a follow up question, please "Start a New Discussion" and we would be glad to support you further.