So I'm doing a board with a few components that have pads named TH (for "thermal", not "through-hole"). The pads are not connected to anything in the library device, and I haven't done anything special with them. One side of the board has a polygon named TH as well.

After using the autorouter, EAGLE gives me a bunch of airwires in places where it wasn't able to connect all the TH pads together. Now, I don't really care about that - is there a way of telling it not to do that? Just hooking them up to whatever part of the TH polygon is around would be fine for me, it doesn't all need to be connected.

  • \$\begingroup\$ I haven't used EAGLE in a while so I'm not going to write an answer, but I think the most sane way is to hide the TH ratsnest. The thermal pads and copper can be rather important, datasheet often have specific layout recommendations. \$\endgroup\$
    – pipe
    Sep 21, 2016 at 20:54
  • 3
    \$\begingroup\$ Possible duplicate of Hide particular airwires/nets in eagle \$\endgroup\$
    – pipe
    Sep 21, 2016 at 20:54
  • 1
    \$\begingroup\$ Don't use autorouters \$\endgroup\$
    – Voltage Spike
    Sep 21, 2016 at 23:25
  • 2
    \$\begingroup\$ This is not a duplicate! The OP should not simply hide the airwires, but should instead take care of the problem. Please see my answer. \$\endgroup\$
    – bitsmack
    Sep 22, 2016 at 0:51
  • \$\begingroup\$ (Actually, I won't have time to make a good answer for a day or two... sorry!) \$\endgroup\$
    – bitsmack
    Sep 22, 2016 at 5:24

2 Answers 2


Why is there a polygon called "TH"? I strongly suspect that if you named it something else, then Eagle CAD wouldn't try to connect all your other TH pads to it. Sounds rather like you shot yourself in the foot.

  • \$\begingroup\$ The thing is that even if I remove the polygon, Eagle still insists on connecting all the TH pads together. Which would've made perfect sense if it was a ground plane or something like that, but in this case it'd be very nice to be able to turn that feature off. \$\endgroup\$
    – Chris
    Sep 22, 2016 at 6:22
  • \$\begingroup\$ You may have to go into the XML file and delete all references to "TH" and force it to re-think the whole situation. \$\endgroup\$ Sep 22, 2016 at 13:10
  • \$\begingroup\$ I'll have a look at that. Another thought, would it be acceptable to connect the thermals to ground? That should pretty much solve the problem I'd think. Not sure if it has any consequences electrically though. \$\endgroup\$
    – Chris
    Sep 22, 2016 at 16:45
  • \$\begingroup\$ @Chris -- connection of Thermal pads to ground or not would depend on the part and manufacturer recommendation. Could you update the post with your component? \$\endgroup\$
    – Wesley Lee
    Oct 22, 2016 at 6:27
pads named TH ... polygon named TH

You told it the pads and polygon are the same net, so of course Eagle will try to connect them. I don't understand how you expect this to work otherwise.

If you don't want them connected, then why why why would you give them the same net name!!?


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