Why does eagle not fill in the ground plane around pads?

[SethGI]

Hi,

This is a random question I've been wondering about for a while. When you have a ground plane in Eagle (or any polygon for that matter) and you add a pad that's connected to ground, why does it draw those four traces to the pad instead of just filling in everything?

I attached a picture as an example.

Thanks!

-Seth

[Richard Crowley]

It is for thermal isolation.  If you tried to solder a component lead in a hole in a large ground plane, the large copper area would sink away the heat rapidly and make soldering difficult and/or damaging to the board and component.

[ataradov]

And you can disable this in the polygon properties. Look for checkbox called "Thermals".

[KL27x]

And to control individual pads, you will want to do that in the library part. There, you can select/deselect thermals as well as paste/cream layer and stopmask for each pad.

Generally, I want to avoid solid connection between pads and ground plane, except where it will actually make an improvement to the board. E.g., on parts that are gonna run hot and be the limiting factor. Or I suppose with high speed/fidelity signals it may make a difference. 

Even thermals can slow down hand-soldering. Where I am going to hand solder I will sometimes use a single trace to connect pads - and then connect that trace to the pour/polygon a ways away. The downside is this will prompt inquiry from my board manufacturer, slowing the turnaround, a tad.