AFAIK, it's mostly used for thermal dissipation, so if you're going to=20
run the PIC fast and let it drive a lot of current, you may want to use=20
it.  I'm never really driven a PIC hard enough to produce any noticeable=20
heat though.  I have a PCB pad below that center pad but don't bother to=20
solder it (as I'm hand-soldering these).

When I use switching regulators that have a center pad, I also place a=20
largish via in the center of the PCB pad, so I can solder (from the back=20
of the board) the pad to the chip, to help dissipate heat.  Some of=20
these are also listed as being connected to ground.

Even if I'm not using it, I leave the pad there, so that no traces go=20
under the chip to cause possible shorts (due to solder bridges between=20
the pins and any traces under the chip).

Cheers,
-Neil.

On 8/21/2012 12:35 PM, Bob Blick wrote:
> In Microchip's packaging document and also the PIC datasheet (in this
> case for the 16F884), in the "land patterns" section, the center pad is
> called "Optional Center Pad" for the QFN packages.
>
> Is that really optional? I can't think of any upside for leaving it out.
> I welcome any thoughts on it.
>
> Thanks,
>
> Bob
>

--=20
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