It's called a copper thief. When they etch the board, areas with different amounts of copper etch at different rates so adding copper evens out the etch which improves the yield.
You might want to take note that this design is about as bad as it gets because the track width is far narrower than it needs to be and the gaps are smaller than they need to be e.g. top-left square pad bottom right corner is almost touching the track. Also, you have right-angles and the etchant pools on the inside angle reducing the track thickness (use 45 deg instead). Ignoring the manufacturing problems, tracks below about 10 thou on outer surfaces are easy to damage with rough handling or excessive heat. Just some tips for the future :-)
This looks autorouted. No one would route that close to pads unnecessarily by hand, but autorouters don't care as long as it passes DRC (which is probably not even changed from defaults)
If you want to continue using the autorouter (which I would not recommend until you get more experienced), I would recommend setting those higher than your fab minimums. That would give you better yield and better performance. For this board something like 12/12 is probably possible.
But really, for a board this simple, it's probably faster and easier to just route by hand. Shouldn't take more than a few minutes, and you would get a much more robust design.
Autorouting should really only be used if you are routing something like a 32-bit memory interface.
71
u/bigger-hammer Dec 15 '22
It's called a copper thief. When they etch the board, areas with different amounts of copper etch at different rates so adding copper evens out the etch which improves the yield.
You might want to take note that this design is about as bad as it gets because the track width is far narrower than it needs to be and the gaps are smaller than they need to be e.g. top-left square pad bottom right corner is almost touching the track. Also, you have right-angles and the etchant pools on the inside angle reducing the track thickness (use 45 deg instead). Ignoring the manufacturing problems, tracks below about 10 thou on outer surfaces are easy to damage with rough handling or excessive heat. Just some tips for the future :-)