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  • TI Thinks Resolved

TAS5624A: Heatsink mounting recommendation : Maximum torque force that IC can sustain

Part Number: TAS5624A

My customer facing some market feedback due to D-amp IC broken.

This D-amp IC broken caused by mechanical heatsink vibration which make some IC pin break.

Customer would like to understand how much kg/f can stand for screw torque or maximum load (kg) withstand when the heatsink mounted on top of the IC.

Customer wants to study to improve vibration to avoid broken pin IC with strengthen the screw torque of the heatsink.

Please provide heatsink mounting data(screw torque) /recommendation for HTSSOP or similar IC package.

Thanks.

Best regards,

Chin

  • In reply to Wee Keat Chin:

    Chin,

    I understand the drawing, thank you.

    It looks to me that even though the heatsink bracket is supported on the PCB surface, the large mass of the heatsink itself is still unsupported. This could mean that the heatsink mass itself could flex the heatsink bracket during vibration and cause damage. Does the system typically see vibration in the normal use case?

    Can the customer check with the silicon pad manufacture and the heatsink manufacturer about the force needed to achieve correct thermal performance?

    Has the customer tried reducing their heatsink screw torque and checked for thermal performance?

    Regards,

    -Adam
  • In reply to Adam Sidelsky:

    Hi Adam,

    Your inference could be correct as customer found out that some of the protruding supports on the heatsink bracket are out of specs(height shorter).

    Hence the heatsink is not fully supported and sitting on the PCB. This failure is so rare as it only happened in one model, coincidentally the heatsink and heatsink bracket used is different from others.

    Customer now is simulating to reproduce the failure. Since vibration is the suspected culprit, their study approach could be finding the resonance frequency.

    Customer wants to understand whether TI happens to encounter similar failure or comments about the resonance frequency that could lead to break the IC pins.

    For the correct thermal performance, do you mean that the minimum torque required in order to achieve the thermal conductivity as stated in the datasheet?

    Example refer to the silicone pad, the thermal conductivity is 1.7W/mK [ISO 22007-2]

    Thanks.

    Best regards,

    Chin

  • In reply to Wee Keat Chin:

    Chin,

    TI uses a heatsink such as the following for the TAS5624:

    https://www.digikey.com/product-detail/en/advanced-thermal-solutions-inc/ATS-TI1OP-519-C1-R3/ATS2180-ND/5125225

    As you can see from the image, the heatsink has feet that touch the PCB on both top and bottom of the IC, also no thermal pad is used, the heatsink rests directly on the IC with thermal paste applied.

    Since we have two square feet touching the PCB surface and no thermal pad, this heatsink is very sturdy.

    We have not heard of any issues like this from other customers.

    The minimum torque mentioned is based on our findings for the amount of torque needed to give us adequate thermal performance in our application.

    Regards,

    -Adam

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