Ultralow dielectric constant polyarylene ether nitrile foam with excellent mechanical properties

Abstract

Low dielectric constant dielectrics possess a broad prospect for application in microelectronic devices. The most efficient method for fabricating low dielectric constant dielectrics is the incorporation of pores into the materials. However, the introduced pores simultaneously decrease the mechanical properties of the dielectrics, which limits further application of these materials. Herein, we report the fabrication of polyarylene ether nitrile (PEN) foams possessing ultralow dielectric constants and excellent mechanical properties via delayed phase inversion method. Scanning electron microscopy (SEM) observations indicate that the porous structure of PEN foams is composed of finger-like pores and cellular pores. Due to the existence of these pores, the density of the PEN foams is as low as 0.158 g∙cm−3, and the homologous void fraction is up to 87.5%. As a result of the high void fraction, the PEN foam demonstrates an ultralow dielectric constant of 1.25 at 1 kHz. On the other hand, deriving from the high performance nature of the PEN, the PEN foams reveal excellent mechanical properties with a specific modulus up to 1027 MPa∙cm3∙g−1 and an elongation at break higher than 22%; additionally, these foams are flexible enough to be folded repeatedly without fracture. The simultaneous achievement of ultralow dielectric properties and excellent mechanical performances intensify the competitiveness of PEN foams for applications in microelectronic devices.