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This article aims to encourage interconnect designers who design for flex or rigid-flex circuits to use the modern CAD tools at their disposal for getting flex done right the first time. While modeling PCBs in 3D is not new, and all the major PCB EDA vendors offer some form of 3D modeling and integration, it is still a rare circumstance that flexible circuit designers use 3D CAD modeling. Most still prefer to design in 2D spaces and build paper dolls.
There are some pretty significant advantages to using 3D-folded flex circuits and multiboard modeling in CAD such as ensuring correct board shape. You can also fold geometries before having to cut even one piece of paper, and avoid building an expensive prototype only to find the flex portion was slightly too long or short or components on the final assembly interfere with each other once it’s all in-situ.
Call me Captain Obvious!
These issues happen because of the disjoint between the design in our heads and the design in CAD. It’s important to recognize that in our own designer’s mind, we are already trying to think in three dimensions—mentally animating assembly processes and folding—and equally important, to recognize the need for capturing that inside view to validate and verify that it can actually work using the tools at our disposal. With plenty of margin and lots of experience, it might work out okay, but there’s no substitute for an accurate model to test.
Less obvious are the secondary and tertiary issues that can be highlighted and effectively dealt with by using 3D-enabled PCB and multiboard system design software. And by that, I mean taking a truly iterative design approach as opposed to the more typical linear method of creating the board outline in MCAD, importing to the PCB editor, developing the component placement and routing, then re-exporting to MCAD. The following are just a few areas where thinking and designing in three dimensions will make a nice improvement to your workflow.
To read the full version of this article which originally appeared in the January 2019 issue of FLEX007 Magazine, click here.