Smooth Joints DFM Action

Introduction

The Smooth Joints DFM rounds corners in flex PCBs to eliminate sharp angles without compromising the board's manufacturability, reliability or electrical netlist.

In flex PCBs, it is recommended that angular corners caused by two traces meeting be avoided entirely. When two lines meet at a sharp angle, a bottleneck may also appear. The Smooth Joints DFM eliminates angular corners and bottlenecks by adding copper and arcs to smooth out the angles.

The Smooth Joints DFM makes selected modifications in the area where two lines meet to eliminate angular joints. Special care is taken to prevent modification near pads, to allow adding standard teardrops after running this DFM.

This DFM can also be used to eliminate "kneecaps", the protruding bump that occurs when two lines of differing widths meet at the end points of an angle.


   

Attributes

The action will copy to the added features all attributes that appear in the original features. In addition, added features will be assigned the " .smooth " attribute, except for arcs that replace angles.

This policy ensures that you can remove lines with the .smooth attribute without affecting connectivity.

The action will disregard crosshatches. This means that the action will not handle lines with .hatch or .hatch_border attributes.

Rules

The DFM smooths the sharp angles generated when lines meet when the following conditions apply.

In addition, one of the following conditions must also be true:

 

 

 

 

The two lines meet at their end points

 

 

 

 

The two lines do not touch, but are joined by a short line

 

 

 

 

 

The two lines meet at a T

  



Notes on Categories 

The action reports certain joints as "not rounded", "partly rounded", "teardrop not added" or "teardrop partly added" if the action cannot add copper to (i.e. "round") these joints because it would cause spacing violations to other copper features, drills, or compensated rout features. This situation will often occur when a joint is very close to a pad (in which case, the location should be treated as a regular teardrop).

Short lines, lines having a length less than 4 times their width, are not rounded.

Joints with more than 2 features are not processed at all.

Square capped lines are not handled.

The action will disregard crosshatches. This means that the action will not handle lines with .hatch or .hatch_border attributes.