TPSM846C24: Heatsink design

Hirotsugu Kobayashi

Part Number: TPSM846C24
Other Parts Discussed in Thread: TPS546C23, TPSM846C23

Hi team,

My customer plans to use a heatsink on the top side of the device.
Is it okay to put the heatsink on top?
If yes, what is the maximum force applied to the package?

Best Regards,

over 2 years ago

0 Caleb Perez over 2 years ago

TI__Genius 11315 points

Hey Hirotsugu,

We don't test maximum load, but if you give me a force in Newtons I can check with the packaging team to see what they think.

Thanks,
Caleb

0 Hirotsugu Kobayashi over 2 years ago in reply to Caleb Perez

Mastermind 9425 points

Hi Caleb,

We want to know the maximum force.
Could you please check the maximum Newtons with the package team?

0 Caleb Perez over 2 years ago in reply to Hirotsugu Kobayashi

TI__Genius 11315 points

Hey Hirotsugu,

I've contacted packaging and asked them for this information. I will get back to you shortly.

Thanks,
Caleb

0 Caleb Perez over 2 years ago in reply to Hirotsugu Kobayashi

TI__Genius 11315 points

Hey Hirotsugu,

I checked with the packaging team. There is no way to know the maximum force. Customer should complete their own testing. We do not have equipment to test force on our modules.

0 Hirotsugu Kobayashi over 2 years ago in reply to Caleb Perez

Mastermind 9425 points

Hi Celeb,

Figure 7 in the application note (SNVA848A) provides with heatsink data.
Please tell me more about this heatsink.

This module top side is inductor, is it OK to attach a metal heatsink?

Best Regards,

0 Caleb Perez over 2 years ago in reply to Hirotsugu Kobayashi

TI__Genius 11315 points

Hey Hirotsugu,

Regarding that graph, the heatsink was tested on the IC package itself, not the inductor. For the IC (QFN, clip), we have experimental data that shows 200N of force is acceptable.

This does not apply to the module, however, as the top side of the module is the inductor, and we do not have force limit data on the inductor pins/solder joints. Assuming that the heatsink is electrically isolated, I don't see why you couldn't experiment with attaching a heatsink to the top of the inductor.

Thanks,
Caleb

0 Hirotsugu Kobayashi over 2 years ago in reply to Caleb Perez

Mastermind 9425 points

Hi Caleb,

The IC is under the inductor, how did you attach the heat sink?
Or is the graph TPS546C23 instead of TPSM846C23?

Best Regards,

+1 Caleb Perez over 2 years ago in reply to Hirotsugu Kobayashi

TI__Genius 11315 points

Hey Hirotsugu,

It seems I was mistaken. You were correct in that the heatsink was placed on top of the inductor for this application note. We don't have any information on the heatsink, however. It is likely that the heatsink had the same area as the inductor and was glued to the top of it.

Regarding heatsinks in general: From mechanical/reliability perspective, the customer will have to test and evaluate their design (thermal interface and how heatsink attaches and touches the module) and ensure it meets their qual/reliability standards. A concern with heatsinking would be that the heatsink would apply stress on the module and solder joints, so the customer is responsible to evaluate and test their design meets their lifetime/reliability requirements. We do not have specific guidelines on heatsink design or application.

Thanks,
Caleb

Power management

Power management forum

TPSM846C24: Heatsink design