Behind the Scenes: PCB Design

This week we have a brand new blog! Just a couple days ago we received a curious inquiry:

“You’ve done a stellar job with improvement from the original [cMoy] design. I am blown away by the PCB work as well. What software did you use to design it, and did you design it yourself? It is definitely a work of art.”

So, here’s a behind the scenes look.

We perform all PCB design work in-house using CadSoft EAGLE Standard, coupled with several free scripts and utilities. Most simulations are run in LTspice IV. Today I’ll focus on how we physically conceptualize our PCBs prior to production.

Serious electronic projects requires collaboration between electrical and mechanical engineers using IDF files, such that the physical design of the PCB can be coordinated to fit the enclosure. This is one of a few areas in which CadSoft EAGLE provides no native abilities. It is possible via scripting, but IDF models are overkill for simple headphone amplifiers in mint tins.

We’ve found three ways to export our EAGLE boards into 3D format. Besides the obvious benefit of viewing a new PCB, accurate 3D models have helped us catch and correct major layout mistakes. In increasing order of capability and cost, they include:

PCB rendered by Eagle3D --> POV-Ray

1) Eagle3D + POV-Ray

Released: June 26, 2002
Cost: $0
The Eagle3D script generates a POV-Ray file. This is great for a quick at the board, but essentially useless for ECAD/MCAD collaboration.

-Minimal preparation, easy use: Script instantly generates a POV-Ray file
-Fairly realistic output

-POVRay renderings are still 2D images, not 3D models
-Rotating the board/camera is painstaking (must manually edit POV-Ray script, re-render, then wait…)
-Difficult to create new component models
-No way to export POV-Ray files to other 3D formats = Useless for mechanical engineering

Same PCB: Eagle'up --> Google SketchUp

2) Eagle’up + Google SketchUp

Released: May 30, 2010
Cost: $0 for script, $0 to $495 USD for SketchUp
This new script creates a true 3D model in SketchUp. Great improvement over Eagle3D, and almost useful for ECAD-to-MCAD collaboration.

-Creates a true 3D model (.skp format)
-3D model exportation possible
-Highly realistic output with external ray-tracing
-Easy to create new component models

-Exporting to .3ds format requires paid version of SketchUp Pro (although a somewhat reliable, free script is available)
-3D imports/exports from SketchUp are unreliable: Mechanical engineer must perform design work in Sketchup (undesirable)

Generate_3d_data.ulp (IDF script) output in SolidWork

3) “Generate_3d_data.ulp” + SolidWorks Premium

Released: September 30, 2005
Cost: $0 for script, $5000+ USD for SolidWorks
Creates mechanically accurate Intermediate Data Format (IDF: .IDB/.IDL, .EMN/.EMP) files for professional 3D circuit board modeling and manipulation in commercial packages, such as SolidWorks Premium.

-Creates industry standard 3D models for ECAD/MCAD collaboration

-Must manually edit every component library to produce component shape/height data
-Very poor English documentation (translated from German)
-No author website, so old script versions are floating around the Internet (find script v0.7 or higher!)
-IDF files only useful to those with expensive software packages

I’m sure I’ve ventured well into boring technical territory for all of you non-engineers/DIY’ers, so I will digress. The cMoyBB v2.03 was the first board we modeled in Google Sketchup. In the last image, you can see a glimpse of a prototype Li-Ion powered, USB rechargeable amplifier modeled in SolidWorks. More to come on that development later!

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