How the non-stretchable flexible PCB can stretch

Stretchable LED lamp wrapped around a tube using a Tomoe type structure.

In response to the increased demand for wearable devices and dynamic applications, several methods for expanding and bending flex PCBs have been proposed in recent years.
Our solution is a stretchable circuit board that uses a Tomoe-type structure.
Although the materials of the flex PCB do not stretch, it is possible to stretch a circuit board by giving it a Tomoe-type structure.

Taking the example of the figure below, when an external force is applied to the stretch, the red area in the figure is lifted from the horizontal and allows for the entire sheet to stretch. This circuit board maintains a constant resistance throughout its extension and allows for soldering, just like an ordinary flexible PCB. In addition, it is also possible to make sheets made from harder or thicker materials more bendable or stretchable by elongating the area marked in red. By applying this kirigami structure to thick materials, it is possible to make durable flexible PCBs.
(currently under development)

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