A Single Process for Homogeneous and Heterogeneous Bonding in Flexible Electronics : Ethanol-Assisted Vacuum Ultraviolet (E-VUV) Irradiation Process

Joining of dissimilar materials is extremely important for flexible electronic packaging, that is generally achieved by assembly of pre-patterned electronic components with organic destination substrates in multi-layered architectures via transfer-printing technique. To avoid thermo-mechanical damages during bonding, organic- and inorganic-organic solid-state direct bonding must be achieved. Here we report a novel bonding process enabling both organic- and inorganic-organic material hybridization. Vacuum-induced reorganization of ethanol was used to achieve multiple effects of surface modification in this method, which has been named ethanol-assisted vacuum ultraviolet irradiation (E-VUV) process. In this study, investigation of X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) was conducted to thoroughly understand adhesion mechanism. The analytical results proved that the E-VUV process was applicable to PEEK-and tin-polyimide bonding, and the bonded interfaces are expected to be robust enough for flexible MEMS packaging.