Fabrication and the film-forming mechanism of thin polytetrafluoroethylene films with enhanced dielectric and mechanical properties

Polytetrafluoroethylene (PTFE) films with outstanding dielectric properties are widely used in the next-generation integrated circuit devices. However, how to prepare the ultra-thin PTFE films with high-performance is still a challenge. In this paper, the PTFE emulsion casting-drying-sintering method was used to prepare thin PTFE films (with the thickness around 20 μm), and the film formation mechanism was investigated. It was firstly detected that the micro-cracks, generated by the solid-liquid-gas interface forces during the horizontal and vertical directional drying of the PTFE emulsion, are the key factors for the performance of PTFE films. After eliminating these micro-cracks through improved drying and sintering processes, the tensile strength of the PTFE films was increased by 3 times. Moreover, the dielectric constant and dielectric loss declined to 2.0 and 0.00065 at 10 GHz, respectively. This work provides an effective strategy to realize the fabrication of high-performance PTFE films without the addition of any additives. [Display omitted] •The casting-drying-sintering method was employed to fabricate the PTFE thin films.•The morphological evolution and the film formation mechanism were deeply discussed.•The micro-cracks induced by capillary pressure affect the performance of PTFE films.•The performance of PTFE films was improved remarkably without adding any additives.