same net spacing

From the image, it looks that these are just two fragments of the same shape and the shape has been fragmented due to the placement of objects inside it. The Same Net Spacing Worksheet checks of Constraint Manager is not configured for such a scenario to catch DRCs within shape fragments of a shape.

To detect these kind of defects, the Same Net Shape-to-Shape Spacing DRC that gets flagged when two different shape entities on the same net are within the specified spacing can be explored.

Setting the Manufacturing > Copper Spacing > Shape-to-Shape constraint flags a DRC at places where the shapes are split with spacing greater than the specified value. This constraint only checks the spacing between any two copper shapes irrespective of the same net or different nets. This is meant for manufacturing limitations.
You can perform the below steps-
1 Go to Setup > Constraints > Constraint Manager.
2 Open the manufacturing worksheet.
3 In the Design for Fabrication tab, go to DFF Constraint Set.
4 Select Copper Spacing and add a value against Shape to Shape CSet here.
5 After assigning this CSet to the design, you should see that the DRC flag to appear for such a scenario as shared in the image.

Ensure to enable the DRC mode using Setup > Analysis Mode under Design for Fabrication>Copper Spacing>Shape-to-Shape from the Constraint Manager window for checking this.

From the image, it looks that these are just two fragments of the same shape and the shape has been fragmented due to the placement of objects inside it. The Same Net Spacing Worksheet checks of Constraint Manager is not configured for such a scenario to catch DRCs within shape fragments of a shape.

To detect these kind of defects, the Same Net Shape-to-Shape Spacing DRC that gets flagged when two different shape entities on the same net are within the specified spacing can be explored.

Setting the Manufacturing > Copper Spacing > Shape-to-Shape constraint flags a DRC at places where the shapes are split with spacing greater than the specified value. This constraint only checks the spacing between any two copper shapes irrespective of the same net or different nets. This is meant for manufacturing limitations.
You can perform the below steps-
1 Go to Setup > Constraints > Constraint Manager.
2 Open the manufacturing worksheet.
3 In the Design for Fabrication tab, go to DFF Constraint Set.
4 Select Copper Spacing and add a value against Shape to Shape CSet here.
5 After assigning this CSet to the design, you should see that the DRC flag to appear for such a scenario as shared in the image.

Ensure to enable the DRC mode using Setup > Analysis Mode under Design for Fabrication>Copper Spacing>Shape-to-Shape from the Constraint Manager window for checking this.

Hi Masama, we discussed this topic internally and tested together. We actually have two checks for you to try. The check mentioned above, Copper Spacing > Shape to Shape, will work for two different same net shapes. This is a Fabrication Core Checks, however using the Extended Fabrication Checks available with the Allegro Venture or Allegro Enterprise licenses, you can use the "Void Slivers" check. If you have this license then please try the Void Slivers check located in the Constraints Worksheet > Copper Features > Minimum > Void Slivers. 

If you do not have this license then please consider adjusting the minimum aperture gap width for your shapes in Global Dynamic Shape Parameters. 

thank u for ur response, john

the problem is a static shape.

when i change a static shape to a dynamic shape. the minimum aperture for gap width does not work.

when the static shape is changed to a dynamic shape, the gap is not based on the parameter of the dynamic shape 

the gap is 25um whereas the dynamic shape parameter setting is 50um.

whern i press the apply button, the gap does not change.

when i change the aperture to 100um and back to 50um, the gap went back to 25um.

then i change the aperture to 51um, the gap became 51um.

when i set the aperture back to 50um, the gap went back 25um.

is the minimum aperture related to same net spacing setup on the constgraint manager?

regards

masa

You're welcome. No this  minimum aperture setting is not related to the same net spacing. This was suggested as a workaround. The minimum aperture represents the gerber artwork apertures. Historically, these large shapes are drawn by a single aperture using a border line and multiple lines to fill the copper plane shape.

This aperture is the "thinnest" possible shape thickness. So actually it represents the positive part of the shape and not the gap. If the copper plane must become too narrow, to a thinner width than the "minimum aperture", then it stops drawing the shape. 

A word of caution: 50um and 25um seems too thin for standard density pcb applications. For example if the minimum signal trace thickness is 125um ( as example only). Then the minimum aperture setting for the shape parameters should also be >=125um. The minimum shape thickness should not be thinner than the minimum signal trace thickness generally.