Soldermask

• IPC Standards Tree (IPC-SM-840)
• Soldermask Registration Accuracy (+/- 3mils)
• Soldermask Expansion (+/- 4mils)
• Soldermask and Fine Pitch QFPs 
• LDI Soldermask Tolerances
• Soldermask on vias and ENIG Finish
• Soldermask Via Encroachment
• Silkscreen to Soldermask Rules
• Soldermask Relieved Vias Script
• Soldermask 3D View
• Soldermask Regions
• Soldermask Dots

Primitive Soldermask

Fills
Tracks
Regions

Smart Soldermask
Polygons ?

Regions with soldermask expansion.

Soldermask Dots (soldermask polygon with cutouts)

Vias can be tented with soldermask rules.

click on image to view

Example: Vias with Soldermask Mask Expansion value from rules. (David Carmody)

Note that if the expansion value is specified, the specified expansion will be used vice the rule.

When vias are first placed in a design the default is to follow the rules.


Soldermask Relieved Vias (Soldermask Encroachment)
Hole size +5mils.  

Soldermask Expansion = ((Pad - (Drill + Relief)) /2) *-1


Soldermask Defined Pad

Mounting Little Foot - Datasheet

User defined soldermask rule for soldermask defined pads.