Circular Boolean Output Formats

Not every output format that GBRUnion can generate supports arc or circle entities. Of the available GBRUnion outputs the following can now include arcs.

1. GDSII - GDSII stream output does not support arcs.

2. DXF - AutoCAD's DXF format does support arcs and composite curves. All output is in the form of zero width closed polylines.

3. Gerber - Gerber does support arcs. Output is generally RS247X using G36/G37 area fill.

4. EGS Archive Agilent's EGS Archive format (used for ADS layout) does support arcs but does not support composite curves nor does Momentum import arcs and composite figures.

5. Artwork ACSII This format does not yet support composite curves but will be updated to do so.

How Metal Islands are Handled

Many Gerber input files contain islands - empty areas surrounded by metal. An island can be formed many ways: some flashes such as donuts inherently include an island as part of the flash definition; multiple strokes can be overlapped to form an island; RS274X paint and scratch layers can form and island and G36/G37 re-entrant polygons can form islands.

Input - a Gerber layout that includes a metal region with a clear island. It does not matter how such an island was achieved.

GBRUnion Output Options

Cut Lines - the island is formed from a single composite curve that has one (or more cut lines where the direction of the "edge" reverses itself.

Butting - The clear island is accomodated using two or more butting figures.

Embedding - The island is achieved by "embedding" a clear figure within a parent dark figure or by using a dark and clear layer (RS274X LPD/LPC layer command)