Novel wiring structure for 3D-conformable devices

Abstract

Wearable products or biosensors require conformability to a complex curved surface or stretching and moving shapes such as parts of the human body. However, it is difficult to apply conventional printed wiring boards (PWBs) or flexible printed circuits (FPCs) to these applications. This situation prompted us to develop a novel wiring structure suitable for 3D-conformable devices. Our structure is composed of spiral-shaped metal wiring and a polymeric insulating layer that has a similar shape. This wiring structure has the following key features: (1) 3D conformability that combines deformability with robustness, (2) low and unchanging electrical resistance during stretching, and (3) a process applicability that allows solder mounting processes or photo processes to be employed to manufacture this device. In this paper, we show the advantages of this structure compared to other conventional types. We also demonstrate a conformable LED matrix display in which LED chips are mounted at the center of each spiral in the array.