Clearance

Rule category: Electrical

Rule classification: Binary

Summary

This rule defines the minimum clearance allowed between any two primitive objects on a copper layer. Use this rule to ensure that routing clearances are maintained.

Constraints

Default constraints for the Clearance rule.

• Minimum Clearance – the value for the minimum clearance required.
• Connective Checking– the scope of the rule with respect to the nets in the design. Can be set to one of the following:
  • Different Nets Only – constraint is applied between any two primitive objects belonging to different nets (e.g. two tracks on two different nets).
  • Same Net Only – constraint is applied between any two primitive objects belonging to the same net (e.g. between a via and pad on the same net).
  • Any Net – constraint is applied between any two primitive objects belonging to any net in the design. This is the most comprehensive of the three options and covers the possibility of the objects belonging to the same net or different nets.

How Duplicate Rule Contentions are Resolved

All rules are resolved by the priority setting. The system goes through the rules from highest to lowest priority and picks the first one whose scope expression(s) match the object(s) being checked.

Rule Application

Online DRC, Batch DRC, interactive routing, autorouting and during polygon placement.

Notes

1. When defining the constraints for the rule, the Connective Checking option would typically be set to Different Nets Only. An example of when Same Net Only or Any Net could be used is to test for vias being placed too close to pads or other vias on the same net, or any other net.
2. When defining a clearance rule for a polygon, it is the primitives of the polygon that the rule is actually applied to, rather than the polygon itself. The keyword entry InPolygon (or InPoly) should be included in the Full Query in this case, instead of IsPolygon (or IsPoly). The specific polygon clearance rule must also be given a higher priority than any general clearance rule, if it is to have any effect.