Adding custom anti-pad for Backdrill in the adjacent layer

Hi JITHINDEV, if you already have a process in place to oversize the anti-pad and generate Route Keepouts in the path of Backdrill then it is possible to activate the BACKDRILL_OVERSIZE_OPTION. Once set this will dynamically add two new options in the Backdrill Setup and Analysis form:

• Disable oversize antipads: Disables canvas replacement of the layer-based antipad using the BACKDRILL_CLEARANCE antipad values in the padstack
• Disable oversize keepouts: Disables the generation of Route Keepouts based on the BACKDRILL_CLEARANCE Keepout values in the padstack

One can now manually implement their own keepouts individually as they see fit. This is not the recommended flow for backdrill however, and for obvious reasons we must use extreme caution when exercising this option to prevent manufacturing issues in your output data. 

Hi John T,

Thank you for your response,
I cannot find the option you suggested in my Orcad 22.1, is there any alternative method ??

Hi John T,

Thank you for your response,
I cannot find the option you suggested in my Orcad 22.1, is there any alternative method ??

Hi  JITHINDEV, you should first activate the BACKDRILL_OVERSIZE_OPTION.  Do this in user preferences and check that preference so that these menus are enabled. 

Hello John T,
Thank you for the clear and thorough explanation.
I noticed that when I select both checkboxes, the entire antipad is turned off. I only want to turn off the antipad of a single layer.

Hi JITHINDEV, apologies but it is currently not possible to disable the backdrill antipad/keepout oversizing per layer only. I suggest that you take care extra when disabling this feature and talk to your pcb suppliers directly. The purpose of this feature is to prevent manufacturing problems. Any issue with a single layer is an issue with the entire pcb. Therefore, it may be best to agree a special tolerance with specific suppliers who can guarantee precise secondary drilling.