PTFE/SiO2 composite ink for direct ink writing

Direct ink writing (DIW) has emerged as the most versatile 3D printing technique for advanced Radio Frequency (RF) device development. And polytetrafluoroethylene (PTFE)-based composites attract much research interest as a fundamental material for RF devices because of their excellent properties. However, the high viscosity and insolubility of PTFE hinder the DIW method applied in PTFE-based RF device manufacturing. Herein we develop an agent-free PTFE/SiO2 composite ink by using fibrillation of PTFE, and the print parameters of the ink are optimized. The continual PTFE fiber networks in the slurry ink make it printable. Benefiting from encapsulating the SiO2 particles by PTFE fiber networks, the interface adhesion between the filler and matrix in the composites is strengthened and the outstanding dielectric properties (dielectric constant is 2.33, dielectric loss is < 2.0 x 10(- 3) in the range of 5-40 GHz) are obtained. Moreover, the low shrinkage (3.74%) during the process provides good shape accuracy for device manufacturing. A promising DIW method and ink for PTFE-based RF devices are provided.