Meeting drawing requirements may be more complex than you think.

As a design is completed, the CAD data and drawing define all the important dimensions and requirements. It is the expectation that when the first shipment is received – and every one after that – the parts will meet all dimensional requirements. But has thought been given to how the manufacturer makes that happen?

It all starts with the CAD data the designer supplies. That data sets the standard. Now it is up to the manufacturer to create the tools to build the part. As it does, keep in mind that the manufacturer does not build a part, it builds a panel of parts. So unless the part is very large, the production panel will hold multiple parts. To accomplish this, the fabricators need to ensure all the features are aligned on all the layers across the entire panel.

As the number of circuit layers increases, so does the challenge of getting everything to align and finish at nominal. The first thing to consider is the materials used to make a circuit are not made of granite. They move in all dimensions, and different materials move differently. Manufacturers need to compensate for the movement. This is done with two techniques: alignment tooling and scaling.

Rotating flex circuits are buildable, but will require additional considerations.

I have an application where I need to make an electrical connection to a rotating shaft. The shaft rotates approximately 180° in each direction. Can a flex circuit wrapped around the shaft like a clock spring accomplish this? Are there any guidelines to follow or ways to predict life expectancy?

While clock spring flex designs are not super common, they are certainly not rare either. I have had multiple successful clock spring flex designs over the years. Most of these initial designs probably would not have performed as desired in the “as received from customer” state, but with a little bit of guidance we tweaked the designs and they all ended up performing well.