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Eagle 7.5.0 Possible Bug: Shorted Signals, no DRC error, bad NC Drill export

e14 Contributor

I've encountered some odd behavior in Eagle 7.5.0 (edit: also verified in 7.3.0 and 6.4.0). Has anyone seen this before? Here's what's happening:

 

There is a via (signal name '+5V'), going through a polygon pour (signal named '-10V'). The polygon pour doesn't isolate the via, and shorts '+5V' to '-10V'. There are no DRC errors, no approved DRC errors, no air-wires. When I export the NC drill file (standard excellon file), I get two .drd files. One with all the drills, as expected, and another with the single via that shorts to the plane. The scary part is that Eagle reports that there are no errors.

 

image

Here's what I see in Eagle.

 

image

Here are the two NC Drill files that are exported from the project. View the full size version, the dots representing the drill hits are small.

 

The two NC drill files are below. Notice that the drill tables are the same for both! Yet one of them has a single drill hit, the via shown above.

NC_Drill.drd.0116

%

M48

M72

T01C0.01500

T02C0.03600

T03C0.03937

T04C0.04331

T05C0.05906

T06C0.15500

%

T01

X278000Y189000

X264500Y194500

<--- SNIP --->

T06

X23500Y22500

X23500Y237500

X368500Y237500

X368500Y22500

M30

 

NC_Drill.drd.0115

%

M48

M72

T01C0.01500

T02C0.03600

T03C0.03937

T04C0.04331

T05C0.05906

T06C0.15500

%

T01

X286000Y182500

M30

  • I redrew the signal using a different layer (bottom instead of mid 2) and the error went away. The via now has the proper isolation distance from the '-10V' polygon pour. Interestingly, Eagle only added the isolation after I had re-drawn via and the top layer signal as well. Interestingly, I had to redraw not only the trace, but the via as well to clear the error, take a look at the screenshots below.

     

    image

    This screenshot was taken after the +5V trace to the via was re-drawn on the bottom layer (instead of mid2). The 'Ratsnest' button was pressed before the screenshot was tanek. Notice that the entire bottom trace, via, and top trace are highlighted as '+5V', yet there is a yellow X through the via, as if it was not connected. Additionally, notice that the isolation of the '-10V' polygon is only up to the trace, Eagle ignores the via!

     

    image

    This screenshot was taken after re-drawing the top signal from C3, the via, and part of the bottom (blue) '+5V' trace. Notice that the isolation from the '-10V' polygon is now correct!

     

    I still have no idea what's going on. Renaming the polygon, or the signal didn't help. Moving the (original) traces and via didn't help. Only redrawing the trace on a different layer fixed the issue. All the while, Eagle never reported a DRC error.