Stretchable Printed Circuit Board Based on Leak-Free Liquid Metal Interconnection and Local Strain Control
Min Seong Kim, Seung‐Hwan Kim, Jungrak Choi, Seonggi Kim, Chankyu Han, Yung Lee, Youngdo Jung, Jaeho Park, Sunjong Oh, Byeong‐Soo Bae, Hyuneui Lim, Inkyu Park
Abstract
In order to realize a transition from conventional to stretchable electronics, it is necessary to make a universal stretchable circuit board in which passive/active components can be robustly integrated. We developed a stretchable printed circuit board (s-PCB) platform that enables easy and reliable integration of various electronic components by utilizing a modulus-gradient polymeric substrate, liquid metal amalgam (LMA) circuit traces, and Ag nanowire (AgNW) contact pads. Due to the LMA-AgNW biphasic structure of interconnection, the LMA is hermetically sealed by a homogeneous interface, realizing complete leak-free characteristics. Furthermore, integration reliability is successfully achieved by local strain control of the stretchable substrate with a selective glass fiber reinforcement (GFR). A strain localization derived by GFR makes almost 50,000% of strain difference within the board, and the amount of deformation applied to the constituent elements can be engineered. We finally demonstrated that the proposed integrated platform can be utilized as a universal s-PCB capable of integrating rigid/conventional electronic components and soft material-based functional elements with negligible signal distortion under various mechanical deformations.