Are vias reliable in flexible circuits?

As we all know, flex PBC is flexible. I am curious about the reliability of vias in it. Is it easy to break?

PCB Assembly
October 27, 2023

As a former circuit board (and flex circuit) designer, I would expect vias in flex circuits to be about as reliable as in more traditional (rigid) laminates. Factors that would influence reliability include:

The amount of vibration and mechanical stress applied to the flex over its lifetime
The thickness of the wall plating in the plated through holes (aka vias)
The quality of manufacture (a flex circuit built by a fab that has experience with the technology will more likely build a reliable part)
The layout of the via pads themselves

In the case of item #4, I would advocate for a “teardrop” shaped pad, to smooth the transition from the trace to the via pad.

This will tend to reduce fracturing where the trace enters the via pad on the flex circuit.

Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.

Oliver Smith

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