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Clearance violation question with vias

Question asked by dgould2 on Apr 24, 2013
Latest reply on Apr 29, 2013 by dgould2



I'm seeing a clearance violation on some via's that I'm having a hard time understanding.


First a PADS question; from the picture I uploaded, what is the reason for the concentric circle around some vias but not around others? For example, DDR2_A7 has a visible pad and drill hole whereas SD_CAS_N has no pad just a concentric circle around it. Both of these vias are VIA_10_20 type. What is the meaning of the concentric circle around some but not others?


Second, I'm getting clearance errors telling me that the SD_CAS_N via is overlapping the trace DDR2_A1:


Error   1 Location 2100.75,3161.21 Level 7

Distance between pad and track too small:

VIA(2104.36,3180.88), TRACE(1823.26,3091.25) overlapping


Error   2 Location 2147.48,3162.31 Level 7

Distance between pad and track too small:

VIA(2152.97,3181.54), TRACE(1973.47,3012.26) overlapping


Error   3 Location 2151.56,3201.49 Level 7

Distance between pads too small:

VIA(2152.97,3181.54), VIA(2153.63,3221.38) overlapping


Error   4 Location 2172.86,3216.93 Level 7

Distance between pad and track too small:

VIA(2153.63,3221.38), TRACE(1885.89,3308.7) overlapping


It appears to be telling me that the concentric circle around SD_CAS_N is overlapping with the trace DDR_A1 yet the SD_DM isn't reporting an error even though it's concentric circle is overlapping DDR2_A3. Any ideas why it would be complaining about the overlap here but not with others? The drill itself is 10 mil in diamter and is represent by the light purple dot. The dark purple pad around DDR2_A7 and others is 20 mil


These signals are all on the default rules hierarchy and the drill to trace distance is set to 8 mil. The trace itself appears


I've also checked to make sure that the signals aren't set as differential pairs or anything else that would affect spacing rules.