A mini-review of ultra-low dielectric constant intrinsic epoxy resins: Mechanism, preparation and application

Epoxy resins are widely utilized in electronics, electrical components, and communication equipment for polymer-based wave-transparent composites. However, the dielectric constant (epsilon) and dielectric loss (tan delta) of common epoxy resins are relatively high (epsilon for 3.8-4.2; tan delta for 0.018-0.025), and the corresponding impact resistance is poor. Thus, it cannot meet the requirements of advanced microelectronic materials. And the epoxy resins prepared by filling the inorganic fillers are difficult to combine the low epsilon with good machining performance. The epsilon and tan delta of intrinsic epoxy resins can be decreased by the synthesis of epoxy monomers and curing agents and the optimization of the final curing network. Meanwhile, the use of some special processing methods, such as the electrospinning technology, is also conducive to reducing the epsilon and tan delta values of final epoxy-cured resins. The factors affecting the dielectric properties of epoxy-cured resins, and the common methods to decrease the epsilon value of epoxy-cured resins are reviewed in this article. Then, the design, synthesis and research progress of ultra-low epsilon epoxy resins are investigated with the relevant academic results. Finally, the development trends and application prospects of the ultra-low epsilon epoxy resins are discussed.