Flexible and quasi-isotropically thermoconductive polyimide films by guided assembly of boron nitride nanoplate/boron nitride flakes for microelectronic application

Abstract

• A hierarchical “brick and plank” structure is fabricated by dopamine modified h -BN nanomaterials. • This special structure can be used to improve the performance of polyimide. • The modified PI films have quasi-isotropic thermal conductivity and high thermal stability. • The modified PI films have good flexibility and excellent electrical insulation. • The modified PI films show faster shape memory response time reducing 50 %. Currently, the application of polyimide (PI) based materials often demands mutual additional properties, such as high thermal conductivity, good flexibility, high thermal stability and low dielectric constant and loss, etc. . Herein, a well-aligned hierarchical “brick and plank” architecture by rational assembly of dopamine modified hexagonal boron nitride flakes and nanoparticles (PDA-BNF@BNNPs) which can effectively improve the thermal conductivity, thermal stability, electrical conductivity, dielectric properties and shape memory performance of pure PI. The alternating stacking of vertically arranged h -BNNPs and horizontally laid h -BNFs yield a quasi-isotropic thermal conductivity of PI films with a high through-plane thermal conductivity of 6.43 W/(mK) and an in-plane thermal conductivity of 11.85 W/(mK) because of the simultaneously vertical and horizontal phonon scattering enabled by the vertically arranged h -BNNPs and horizontally laid h -BNFs. Besides, this special structure also endues PI films high thermal stability of over 560 °C, prominent electrical resistance of over 1.40 × 10 -13 Ω•cm, and low dielectric loss of less than 0.02 in the high frequency. Moreover, the PDA-BNF@BNNP/PI films exhibit excellent flexibility and shape memory performance with faster recovery response time reduced over 50 % comparing with that of pure PI film. These outstanding properties combining with the facile and scalable fabrication process make PDA-BNF@BNNP/PI films are very promising in diverse electronic device applications, especially in flexible electronic devices or circuits requiring additionally high thermal conductivity and low dielectric loss.