Dual‐Effect Coupling for Superior Dielectric and Thermal Conductivity of Polyimide Composite Films Featuring “Crystal‐Like Phase” Structure

Abstract

To match the increasing miniaturization and integration of electronic devices, higher requirements are put on the dielectric and thermal properties of the dielectrics to overcome the problems of delayed signal transmission and heat accumulation. Here, a 3D thermal conductivity network has been successfully constructed inside the PI matrix by the combination of ionic liquids (IL) and calcium fluoride (CaF2) nanofillers, motivated by the bubble‐hole forming orientation force. Benefiting from the 3D thermal network formed by IL as a porogenic template and “crystal‐like phase” structures induced by CaF2‐ polyamide acid charge transfer, IL‐10 vol% CaF2/PI porous film exhibits a low permittivity of 2.14 and a thermal conductivity of 7.22 W∙m−1∙K−1. This design strategy breaks the bottleneck that low permittivity and high thermal conductivity in microelectronic systems are difficult to be jointly controlled, and provides a feasible solution for the development of intelligent microelectronics.This article is protected by copyright. All rights reserved

Synergies and applications of polyimides featured low permittivity and high thermal conductivity

“…Latest research reported by our team directly demonstrates the above point [19]. In figure 4(a), a three-dimensional (3D) porous composite network in a PI matrix for the first time by using natural fluorite (calcium fluoride, CaF 2 ) as a thermally conductive filler and ionic liquid as a porogenic agent.…”

“…Recently, the use of PI for wafer-level packaging based on multilayer wiring process has been reported [17,18]. Nevertheless, the amorphous morphology of PI makes it challenging to synergistically modify the low permittivity and high thermal conductivity [19]. Most research efforts have also been limited to unilaterally modulating the dielectric property or thermal conductivity of PIs.…”

Effect of the Structure of Epoxy Monomers and Curing Agents: Toward Making Intrinsically Highly Thermally Conductive and Low-Dielectric Epoxy Resins

“…However, conventional epoxy resins normally generate an unordered cross-linked network after curing, resulting in severe phonon scattering and thus a low inherent thermal conductivity of merely around 0.2 W/(m·K). , Additionally, very polar groups including hydroxyl, imide, or ester will be generated alongside the ring-opening of the epoxy group during curing, hence forming dipole or interfacial polarization. Thereby, the ε and tan δ will be increased, which in turn will cause the accumulation of heat to the substrate as tan δ corresponds to the amount of electrical energy converted to heat under an external electric field. , Meanwhile, it also leads to signal loss or distortion . Therefore, developing epoxy resins with both high intrinsic thermal conductivity and low dielectricity will further broaden their applications and promote the development of high-tech electronic products.…”

“…Furthermore, researchers also prepared epoxy resins with low dielectric properties by applying an anhydride curing agent or introducing imide moieties and low-polarizable C–Si , or C–F − bonds. Meanwhile, introducing fluorine has been shown to greatly increase the formation of liquid crystallinity, thereby enhancing the heat conduction efficiency. However, making epoxy resins simultaneously with increased intrinsic thermal conduction and very low dielectric properties is still challenging and has rarely been reported so far.…”

“…Thereby, the ε and tan δ will be increased, which in turn will cause the accumulation of heat to the substrate as tan δ corresponds to the amount of electrical energy converted to heat under an external electric field. 17 , 18 Meanwhile, it also leads to signal loss or distortion. 19 Therefore, developing epoxy resins with both high intrinsic thermal conductivity and low dielectricity will further broaden their applications and promote the development of high-tech electronic products.…”