Secrets to Optimizing 3D STEP files from your Gerber, ODB++, and GDS-II data.
3D Simulation and Analysis tools have increased design performance, minimized re-spins, and improved reliability to get your products to market faster. Most of these Simulation and Analysis tools require that you import 3D STEP files (AP 203, AP 214, AP 242). However generating usable 3D STEP files from your Gerber, ODB++, and GDS-II data can be a challenge. There are 2 primary bottle necks when using 3D STEP files for Simulation and Analysis tools. 1. Import File Size Many STEP files can be over 500 MB for an average PCB design. Why? PCB designs consist mostly of rounded objects; for example, Traces have rounded end-caps, drilled vias and holes are round, and a majority of pads are round. Whenever round shapes are used, the number of vertices (i.e points) required can be exponentially high. Fortunately STEP files directly support arcs, circles, and curves. While substituting many rounded objects with curves may reduce the final STEP file size, it doesn't necessarily solve the second bottle neck issue #2 (see below). 2. Complex Internal Mesh Generation After importing a 3D STEP file into Simulation and Analysis tools, they must generate complex internal meshes which are used to perform the calculations needed to analyze your design. If your STEP file contains arcs, circles, and curves - guess what - they must all be broken down to hundreds of thousands of vertices again. Most Simulation and Analysis tools do a poor job extracting vertices from arcs, circles, and curves. Typically their own internal meshes become exponentially larger and extremely memory intensive to handle - resulting in extremely slow performance or the dreaded frozen screen. Note: Believe it or not, holes and vias are typically the biggest culprit. Usually most Simulation and Analysis tools generate up to 10X more vertices for holes & vias in their internal meshes than necessary. By eliminating arcs and curves from the STEP files, Simulation and Analysis tools will no longer waste processing power extracting vertices and can more quickly generate it's internal meshes - resulting in faster and more efficient processing times. In addition, by eliminating Curves (especially in holes) you have more control of the internal mesh used in simulation and analysis. The Secret: The secret is to find a mutually beneficial balance between STEP file size and optimized objects in the STEP file that will allow the Simulation and Analysis tools to quickly generate the internal meshes. We recommend using these options when generting your STEP files from your Gerber, ODB++, and GDS-II data. (screen capture of ACE Translator 3000 - STEP Export General Options) Set Arc Precision: 12 (Segments / 360 degrees). 12 segments gives a good balance of keeping file size small, yet still allows Simulation and Analysis tools to product good results. Check Join Adjacent Traces: Will automatically connect any traces that connect which limits the vertices used between the traces. Resulting in smaller STEP files that are more easier to load and process in 3D Simulation and Analysis software. (screen capture of ACE Translator 3000 - STEP Export STEP Options) Uncheck the option