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LMG3411R150: Recommend isolation method between the GaN and heatsink

Yishan Chen
Intellectual 1830 points

Part Number: LMG3411R150

Tool/software:

Hi Team,

Customer is asking about the recommend isolation method between the GaN and the heatsink.

What kind of heatsink are frequently using or recommend to use base on your knowledge and experience? For example, what kind of material of insulator?

Another question is, Do we have the experience of the desoldering between the QFN(GaN) package and the PCB board, do we have any method to decrease this potential risk? Customer is worried about this question is because they need to use screw to fix the heatsink, the mechanical stress may cause the desoldering.

Thank you,

Yishan Chen

  • 0
    TI__Expert 4520 points

    Hello  Yishan,

    Between GaN and heatsink, we recommend using a thermal insulating material (TIM). For top-side cooled devices, the TIM will be placed between GaN device surface and heatsink, usually around 1mm thickness depending on Z height of GaN device.
    For bottom-side cooled parts such as LMG3411 as you mention in this thread, TIM material will be placed between backside of PCB and heatsink, this can be thinner around 0.5mm.
    For a reference. we have multiple application notes on our Seismic applications page that detail everything about thermal design including specific TIM material, I urge you to view it.
    Seismic link

    Using TIM will help board level reliability (BLR) of GaN device. Soldering heatsink directly to GaN device is not recommended and will cause stress issue.
    When using GaN devices, TI recommends using filled and capped vias beneath the device. This will greatly improve solder of device and help BLR.
    Application notes in Seismic link have details about mounting techniques for heatsink. Our EVMs use push-pins with springs, however screw mounting is very common.

    Thanks,
    Zach Soviero