I have designed multiple small PCBs for personal projects, and have used USB ports many times for an output. I have always wondered if it is a good idea to connect the two mounting holes for the USB port together via traces.

Is this a good idea or does it even matter?

Picture of USB footprint: USB footprint

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    \$\begingroup\$ Usually they are connected to the protective earth/chassis net. \$\endgroup\$ – Eugene Sh. May 12 '17 at 20:25
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    \$\begingroup\$ Does not matter as there is already continuity between the two from the mechanical design. \$\endgroup\$ – Misunderstood May 12 '17 at 20:27
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    \$\begingroup\$ They are connected through the metal case of the USB jack itself. No real need to connect them on the PCB too. (Related threads: USB micro B receptacle has 6 mounting tabs. How many do I actually need to ground?, How to connect USB Connector shield?) \$\endgroup\$ – Nick Alexeev May 12 '17 at 20:34
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    \$\begingroup\$ Connecting the through holes to surface copper (especially on the opposite side) will make them stronger; practically that usually means you connect them to ground. \$\endgroup\$ – Chris Stratton May 12 '17 at 20:58
  • \$\begingroup\$ What's your green pour? You could pour on top and connect that to chassis ground? \$\endgroup\$ – uint128_t May 13 '17 at 0:28

Mechanical reasons, the more copper around connectors the better so if your worried about it ripping off of the board more copper will give you more leeway before it comes off the board.

You will get half of the inductance if you connect both so if your worried about radiated emissions out to the cable or conducted emissions to your board (assuming you have one ground and not a shielded ground.)

The shield is already tied in the case so the yellow trace is redundant.

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