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TPSM846C24: TPSM846C24 is QFM (MOL)

Yuhsuan Chang
Prodigy 50 points
Part Number: TPSM846C24

The footprint of TPSM846C24 is QFM (MOL). There are some questions about that.

Does SOLDER MASK OPENING TYP(green solid line) mean that the footprint is on the IC?

Does METAL UNDER SOLDER MASK TYP(blue dashed line) mean that the footprint is on the PCB?

There are also some extra vias in dashed line. What are those vias for? ex: Thermal / strength

  • 0
    TI__Guru 55485 points

     

    Yuhsuan Chang said:
    Does SOLDER MASK OPENING TYP(green solid line) mean that the footprint is on the IC?

    This is the TI recommended Solder Mask Opening for connecting the device pins to the PCB pads.  The solder mask opennings are not exact matches of the device pins, as they provide additional openings for solder fillet and device positioning.  This is part of the PCB design.

    Yuhsuan Chang said:
    Does METAL UNDER SOLDER MASK TYP(blue dashed line) mean that the footprint is on the PCB?

    This is TI recommended extension of the PCB surface copper area beyond the solder mask opening and protected by a non-conductive, non-soldering solder mask. This is part of the PCB design.

    Yuhsuan Chang said:
    There are also some extra vias in dashed line. What are those vias for? ex: Thermal / strength

    These additional via in VIN, PGND, and VOUT are recommended for thermal dissipation and current density due to the high currents in VIN, VOUT and GND.

  • 0 in reply to Peter James Miller
    Prodigy 50 points

    Thanks!

    Is copper keep-out area empty for all layers or only top layer?

    Is copper keep-out area for better return path of BP_RTN/BP6_RTN/BP3/BP6.

  • 0 in reply to Yuhsuan Chang
    TI__Guru 55485 points

    Yuhsuan Chang said:
    Is copper keep-out area empty for all layers or only top layer?

    The Copper Keep-out areas are only on the mounting surface layer, whether that's top or bottom. 

    Yuhsuan Chang said:
    Is copper keep-out area for better return path of BP_RTN/BP6_RTN/BP3/BP6.

    The copper keep-out areas are included because there are conductive test-pads on the bottom of the TPSM846C24 at these locations that are not intended to be connected tot he PCB and if there is PCB copper under them, even with solder-resist, there is a risk of shorting those pads to the PCB copper.