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PowerPAD

quekyb
Intellectual 1025 points

The PowerPAD package is a thermally enhanced, standard-size IC package designed to eliminate the use of bulky heat sinks and slugs.
The PowerPAD package works by conducting thermal energy away from the silicon through thermal vias placed below the PowerPAD (exposed metal). 
The PowerPAD needs to be soldered to an exposed surface on the PCB and sufficient GND plane is needed to dissipate the thermal energy.

For more explanation on PowerPAD, refer to SLOA120, SLMA004B or SLMA002D.

  • 0
    TI__Guru**** 189401 points

    I would add that 99% of our devices in PowerPAD should have the pad tied to ground. However, just to keep everyone on their toes, 1% are different. For example, the TPA4411RTJ specifies to have the pad tied to a floating plane. You can find this on page 3 of the data sheet in the Terminal Functions table.

    It is critical that the pad is soldered down for PowerPAD and QFNs. Our packages depend on that connection for mechanical robustness. If you leave the pad unsoldered, you risk reliability problems if the board is flexed. It is especially critical with QFN packages.

    The connection also helps ground the substrate of the IC die. We have seen cases where customers have had flakey failures that mysteriously went away once they soldered the pad to the recommended potential. Rework is not hard, especially if you have a hot air gun/tool.

    However, this path is not a controlled path, and the impedance you measure from the pad to one of the ground pins of the package will vary wildly due to the way the circuit design was done, as well as how much oxide grew on the back-side of the wafer before we packaged the wafer.

    -d2