Preparation of Polyimide Films with Ultra-Low Dielectric Constant by Phase Inversion

Panpan Zhang,Lize Zhang,Jiupeng Zhao,Yao Li,Ke Zhang

doi:10.3390/cryst11111383

Abstract

Due to the high value of its dielectric constant, polyimide does not meet the requirements of the development of integrated circuits and high-frequency printed circuits. The development of novel low dielectric constant polyimide materials for the preparation of flexible copper clad laminates is of theoretical and practical significance in the application of polyimide for 5G communications. In this work, different fluorinated graphene/polyamic acids (FG/PAA) were used as the precursor, and the porous polyimide film was successfully prepared by phase inversion. The dielectric constant of the porous polyimide film is relatively low, being less than 1.7. When the content of fluorinated graphene is 0.5 wt%, the overall dielectric performance of the porous film is the best, with a dielectric constant of 1.56 (10 kHz) and a characteristic breakdown field strength of 56.39 kV/mm. In addition, the mechanical properties of the film are relatively poor, with tensile strengths of 13.87 MPa (0.2 wt%), 13.61 MPa (0.5 wt%), and 6.25 MPa (1.0 wt%), respectively. Therefore, further improving the breakdown resistance and mechanical properties of the porous film is essential for the application of porous ultra-low dielectric polyimide materials.

Highlights

Flexible printed circuits (FPC) have been widely used in sophisticated electronic products because of their outstanding characteristics, such as having a light weight, thin structure, and good bending
With the arrival of the 5G era, electronic products are developing in the direction of high-frequency and high-speed digital signal transmission, and the demand for high-frequency and high-speed FPC as the carrier of signal transmission is increasing
Previous research has indicated that reducing the dielectric constant of the materials used in the dielectric layer of the substrate is the most effective and direct way to improve the transmission speed and efficiency of microelectronic devices and promote the high-frequency and high-speed development of the FPC

Summary

Introduction

Flexible printed circuits (FPC) have been widely used in sophisticated electronic products because of their outstanding characteristics, such as having a light weight, thin structure, and good bending. Previous research has indicated that reducing the dielectric constant of the materials used in the dielectric layer of the substrate is the most effective and direct way to improve the transmission speed and efficiency of microelectronic devices and promote the high-frequency and high-speed development of the FPC. Polyimide has long been used for the interconnection between metals in electronic devices as an excellent insulating dielectric layer owing to outstanding mechanical and heat-resistant properties [1,2]. Polyimide films, restricted by high dielectric constant (3.1~3.5) [3], have not been able to meet the requirements for the rapid development of modern integrated circuits and high-frequency circuits [4–7].

Results

Conclusion