Directly Printed Interconnection Wires between Layers for 3D Integrated Stretchable Electronics.

Multilayer circuits, especially in stretchable electronic devices, are considered to be an effective way to integrate various components and modules for complex functions. However, the existing manufacturing methods for multilayer flexible and stretchable electronics have problems such as complex technology, expensive equipment, and low production efficiency. Here, a direct ink writing 3D printing method is proposed to fabricate multilayer stretchable electronic devices by using high‐viscosity stretchable silver paste as the material for interconnecting wires, and stretchable polydimethylsiloxane as the dielectric layer. The optimal range of printing parameters is explored to realize the stable and repeatable manufacturing of wires. A protective layer is printed on the interconnection wires and rigid components to connect the soft substrate and the rigid electronic components. The results show that stress concentration is reduced and stable electrical response of the device is achieved under more than 49% tensile deformation. Vertical interconnect accesses and arc‐shaped wires are applied to a multilayer flexible thermal imaging display device and a NE555 timer device, and the outcomes prove that the direct ink writing 3D printing method provides an efficient, simple, and low‐cost manufacturing method for fabricating multilayer stretchable electronics. [ABSTRACT FROM AUTHOR]