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ACIS Output from 3DVU

The ACIS save file (from here on referred to as ACIS) can be imported by a large number of 3D CAD and FEA tools - in particular we are interested in Maxwell and HFSS as originally developed by Ansoft.

Our objective is to take standard PCB formats such as ODB++ and Cadence Allegro/APD/SIP and produce an ACIS output that is properly healed so that it can be correctly meshed and simulated. We already have two tools: NETEX-G for ODB++ files and AWROut for Cadence layout tools that can produce our 3Di file format. So the goal then, is to convert the 3Di -- which is a 2 1/2D database, into a proper solid body ACIS file.

We also want to "mark" the solid bodies using attributes with a net name and a material (if they are conductors) or with a material if they are dielectrics. Now very few programs would be able to read such attributes except possibly Ansoft's Maxwell and HFSS.

While one can purchase a commercial library for producing ACIS, we choose to directly write ACIS for both cost and control reasons. We have already developed algorithms for writing the STEP format and the geometry is similar in many ways to ACIS. Therefore it is necessary to understand fairly precisely the proper geometry and syntax needed to provide a valid file.

Fortunately we don't need to use the entire set of possible ENTITIES - we really only need a subset of the possible geometry classes. These include:


POINT
VERTEX
EDGE
COEDGE
STRAIGHT-CURVE
LOOP
FACE
SHELL
LUMP
BODY
ATTRIBUTE



Links and Resources
The ACIS Kernel   PDF - a series of chapters discussing the ACIS Kernel, classes, programming techniques ...
 
Simple Copper Slab   A single rectangular extrusion generated in SolidWorks and converted into ACIS. The simplest possible output. A line by line analysis of the .sat file with illustrations.
 
Single Copper Slab with Cut   A rectangular extrusion generated in SolidWorks; then a "hole" is cut through it and converted into ACIS. This represents either a conductor with an island or a dielectric with drill holes. An analysis of the .sat file with illustrations.
 
Two Copper Slabs   Two solid bodies (a single "part") created in SolidWorks and converted into ACIS. Designed to illustrate the options for BODY and LUMP.
 
Hierarchical Copper Slabs   A single extrusion in a part; the part is then placed two times and an assembly is created. Then exported to ACIS. Since we normally aggregate all of our PCB layers into parts and place them into an assembly we need to understand what options there are in ACIS to provide this type of organization.
 
Attributes from Maxwell   A design in Maxwell is exported to ACIS and we examine the attributes that were generated and try to determine their function.