Converting PCB designs to 3D STEP

This article describes the best possible methods to convert a 2D Printed Circuit board design (PCB) into a 3D STEP file - which may be used by any 3D CAD SOFTWARE application. It explores the potential pitfalls of converting PCB designs which have plagued 3D software tools for many years.  Includes several tips and tricks to help improve the resulting 3D STEP files. Lastly promotes creating your own unique 3D Conversion Strategy to ensure accurate conversions with faster performance - resulting in smaller more optimized 3D STEP files.

For PCB designers, a 3D STEP file can be essentially considered as the Gerber file of the 3D Design and Modeling world.  Both 3D STEP and Gerber formats were conceived in the previous century and still widely used almost 50 years later. Both are primarily used for manufacturing purposes and design transfer between various CAD/CAM systems.  The 3D STEP format is still accepted by all 3D design/modeling software including SolidWorks, Invertor, Pro/Engineer and more. The Gerber format is still accepted by all PCB Manufacturing software tools.

  • Reasons for converting a PCB design to 3D STEP

Knowing beforehand, why you require a PCB design to be converted into a 3D STEP file and what you wish to accomplish with it - will drastically improve the chances of success.  Here are the primary reasons someone may want to convert their PCB Design to 3D STEP:

 Simulation / Analysis:  Used to perform PCB design analysis such as Thermal Electromagnetic Solvers and Simulation software; in 3rd party software that cannot be performed inside the PCB design software.

 PCB Enclosure Fit: Generates a rough draft preview of the PCB with Components.  Typically used for mechanical purposes such as enclosure fit testing of the final PCB design, etc.

 Printed Circuit Board:  Generates a realistic preview of the finished PCB design.  Usually for documentation, marketing and/or sales purposes.

 Other:  3D STEP files are widely used for various other purposes.

  • Potential PCB to 3D STEP Conversion Pitfalls

 Extremely Large 3D STEP File Sizes: 3D STEP file sizes are typically larger than all other CAD and EDA formats.  This is primarily due to the large number of internal references, geometric redundancies and the formatting of 3D STEP file itself.  

 Slow Loading into my 3D Modeling applications: 

No matter how fast a PCB design to 3D STEP file conversion takes, chances are any large 3D STEP files may still takes hours while importing into various 3D Modeling applications.

 B-Reps are Usually Responsible:  B-Reps (Boundary Representations) have been the most common culprit for producing exponentially large 3D STEP files that also load slowly into various 3D Modeling applications.  Why? To construct a B-Rep requires a huge amount of data stored inside a 3D STEP file (see below: Use Arcs example).

  • Tips and Tricks to Improve converted 3D STEP files

 Use Arcs (when possible):   

Most conversion tools will approximate arc-points by degrees.  

For example: If approximating a Circle using 5-Degrees will generate a circle with 72 points. Each point contains separate X,Y,Z coordinates that must be stored inside the 3D STEP file, plus the 72 edges (i.e lines) to connect the points.  If extruding this simple 2D Circle to become a 3D B-Rep (i.e appearing as a cylinder), 72 more points and edges are also stored for the bottom, plus 74 Solid surfaces (including surfaces for Top/Bottom sides), include storing additional tolerance and attribute information required by the B-Rep - and you've already got a very large 3D STEP file.

Always try to Output Arcs for best quality and smallest 3D file possible.

 Separate 3D STEP file per PCB Layer: Creates a separate 3D STEP file for each PCB layer. Useful to reduce STEP files sizes and allows each file to be imported as separate assemblies in 3D simulation software. 

 

 

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