topic Re: CAM processor generates excessive d-codes for rounded SMD pads in EAGLE Forum

CAM processor generates excessive d-codes for rounded SMD pads

matt.libertyTSE5C — Fri, 08 Jun 2018 21:52:20 GMT

I am using the CAM processor in Eagle 9.0.1 standard to generate gerbers. I had a board come back from fab with occasional very thin lines of solder mask over the pads. The problematic packages had SMD pads with roundness set to 25%. I inspected the gerbers using GerbView from KiCad. I see adjacent d=codes that sometimes have black lines between them:

Adjacent d-codes

This image was of the top copper layer, but the solder mask is similar. I see the same issue with d-codes and black lines between them when using gerbv.

I suspect that the board fab house was not able to correctly merge the adjacent d-code regions.

When I remove the roundness from the SMD pad in the package and ensure that the DRC -> Shapes -> Smds -> Roundness is also 0, the CAM processor emits a single d-code for the pad:

If I then turn on SMD pad rounding in DRC->Shapes->Smds -> Roundness (I used 0, 25%, 2mil), then the excessive d-codes come back. Interestingly, polygons with rounded corners (due to trace thickness) in packages generate correctly. I suspect that the value Eagle uses internally for the SMD's polygon "trace width" is too small. I do have some fine-pitch parts with small pads, such as XQFNs. I do not know how to change or set that "trace width" value like you can with polygons.

Here are some related forum posts:

Simple copper pour gerber size is huge

Gerber lines in ground plane

Any suggestions on how to get rounded SMD pads that generate cleaner gerber d-codes so that they fab correctly?

Re: CAM processor generates excessive d-codes for rounded SMD pads

jorge_garcia — Wed, 13 Jun 2018 17:53:09 GMT

Hello @matt.libertyTSE5C,

I hope you're doing well. We are having trouble reproducing the issue you are seeing. Could you provide more information?

If you can provide a small sample board showing the issue that would be best, however if for some reason that is not possible then let us know the SMD pad dimensions you used and the Mask Parameters(Go to the DRC > Masks Tab) of your design.

Please let me know if there's anything else I can do for you.

Best Regards,

Re: CAM processor generates excessive d-codes for rounded SMD pads

matt.libertyTSE5C — Thu, 14 Jun 2018 00:16:19 GMT

Hi Jorge,

Thanks for looking into this issue. I have created and attached a minimal example that demonstrates the problem. The ZIP file contains a README.txt that describes the files. Please let me know if you are able to duplicate the problem. You may need to change the zoom level (in or out) in gerbv and GerbView to see the lines (presumed gaps between each d-code), but GerbView does show the many small d-codes.

This issue did affect a small prototype run, so I look forward to hearing what you find.

- Matt