External heatsink for FET with SON package

David Park

Expert 6700 points

Other Parts Discussed in Thread: CSD18540Q5B

Hi,

Customer is adopting CSD18540 SON package and it is on Top layer and there are many via holes for thermal performance.

If they add external heatsink, which side has better thermal performance? top or bottom?

Thanks.

over 9 years ago

0 Brett Barr1 over 9 years ago

TI__Mastermind 18200 points

David,
i am glad to hear your customer is using the CSD18540Q5B. Let me make sure I understand your question.

You are asking whether it is better to put the heat sink on top of the plastic SON5x6 package, or under the PCB, correct?

Can you describe the PCB board and heat sink you are considering?

0 David Park over 9 years ago in reply to Brett Barr1

TI__Expert 6700 points

Hi Brett,

yes, correct.

Below is Top and bottom of PCB.

On top, heatsink can be on FET package.

On bottom, heatsink can be on via hole.

Thanks.

0 Brett Barr1 over 9 years ago in reply to David Park

TI__Mastermind 18200 points

I checked with our apps team and they were confident that because you have thermal vias, it will be more effective to heat sink the bottom of the PCB.

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External heatsink for FET with SON package