Set Teardrop Attribute Cleanup Action

Introduction

Set Teardrop Attribute is a cleanup action intended to identify teardrop features in a layer that are not marked with the .tear_drop attribute. 
Teardrop features can be a line, an arc, a pad or a surface.

A teardrop is a feature or set of features that is added to a connection between a pad and a trace entering the pad.
The teardrop strengthens the connection between the pad and the incoming trace.

Teardrop Examples

 

Incoming Trace

A normal trace, line, or arc which connects the pad to the other feature.

 

Teardrop

Feature which connects a pad and a line entering the pad.

A feature can be a line, an arc, a pad, or a surface.

 

Swallow shape teardrop

Skeleton of the line teardrop is shaped like a swallow (a type of bird).

 

Oval shape teardrop

Skeleton of the teardrop is shaped like an oval.

Surface shape teardrop

Skeleton of the teardrop is shaped like an oval.

How the Algorithm Identifies Teardrops

For line or arc teardrops (center_trance type)

The algorithm locates where the trace enters the pad, then identifies the features that connect to the pad at the point where the trace enters the pad.

For pad/surface teardrops

The algorithm determines whether the candidate teardrop pad or surface is closer to the pad being enlarged, then determines if the surface width is larger than the trace width. If the surface width is larger than the width of the trace, than the surface is a teardrop.