Manufacturing Rule Types

• IPC Class 2 (Commercial/General Electronics): recommends a minimum annular ring of 0.15 mm (6 mils) on external layers.

• IPC Class 3 (High-Reliability / Aerospace / Medical): generally demands 0.2 mm (8 mils) or strict adherence to specific ring allowances to ensure long-term mechanical and electrical resilience

Standards define a minimum value for the annular ring, but these values can be reduced further. The reason why they are defined at the levels they are is to guard against drill breakout. Drill breakout occurs as a result of several manufacturing parameters (e.g. hole location, hole size, film expansion) interacting unfavorably with one another, leading to the hole being drilled in such a position as to cut through the connecting copper track(s). It is possible to control drill breakout by applying teardrops to required pads and vias. Teardropping (otherwise known as filleting, or tapering) is the process of applying additional land area to the pad/via at the junction with any connecting track(s). Learn more about defining teardrops.

Specifies the method used in defining the minimum/maximum hole sizes:

• Absolute - the values for minimum/maximum hole sizes are absolute values.

• Percent - the minimum/maximum hole sizes are expressed as percentages of the pad/via size.

Enable this option to allow micro vias to be stacked.

Choose a checking mode for the clearance:

• Check Clearance To Exposed Copper – in this mode, clearance checking is between silkscreen (Top/Bottom Overlay layer) objects, and copper in component pads which is exposed through openings in the solder mask.

• Check Clearance To Solder Mask Openings – in this mode, clearance checking is between silkscreen (Top/Bottom Overlay layer) objects, and solder mask openings created by objects that include a solder mask, such as pads, vias, or copper objects with the Solder Mask Expansion option enabled.

The value for the minimum clearance required. A value entered here will be replicated across all cells in the Minimum Clearance Matrix. Conversely, when a different clearance value is entered for one or more object pairings in the matrix, the Minimum Clearance constraint will change to N/A, to reflect that a single clearance value is not being applied across the board.

Provides the ability to fine tune clearances between the various object-to-edge clearance combinations in the design.

• The default Board Outline Clearance rule for a new PCB document will default to use 10mil for all object-to-edge clearance combinations. When creating a subsequent new rule, the matrix will be populated with the values currently defined for the lowest priority Board Outline Clearance rule.

• To allow an object-kind to cross an edge, set the clearance value to zero. Zero indicates to the software that an object-kind is allowed to violate (pass over) this edge type. Use this technique to allow routed tracks, for example, to travel across from one Layer Stack Region to another.

Definition of clearance values in the matrix can be performed in the following ways:

• Single cell editing - to change the minimum clearance for a specific object pairing.

• Multi-cell editing - to change the minimum clearance for multiple object pairings:

  • Use Ctrl+Click, Shift+Click, and Click+Drag to select multiple cells in a column.

  • Use Shift+Click, and Click+Drag to select multiple contiguous cells in a row.

  • Use Click+Drag to select multiple contiguous cells across multiple rows and columns

  • Click on a row header to quickly select all cells in that row.

  • Click on a column header to quickly select all cells in that column.

• With the required selection made (either a single cell or multiple cells), making a change to the current value is simply a case of typing the new value required. To submit the newly entered value, either click away on another call, or press Enter. All cells in the selection will be updated with the new value.

• To set a single clearance value for all possible object pairings, simply set the required value for the Minimum Clearance constraint. On clicking Enter, this value will be replicated across all applicable cells of the matrix. Alternatively, click the blank grey cell at the top-left of the matrix, or use the Ctrl+A shortcut. This selects all cells in the matrix, ready to accommodate a newly-entered value.