Preparation of fluorinated poly(benzoxazole-co-imide) with low dielectric constants based on the thermal rearrangement reaction of o-hydroxy polyimides

Abstract

As ultra large-scale integration (ULSI) circuits develop quickly, traditional polyimide (PI) urgently needs modification due to its high dielectric constant, to make it meet the requirements of ULSI development. In this study, the o-hydroxy polyimide structure was introduced into the PI main chain, and it was confirmed that the thermal rearrangement reaction of o-hydroxy polyimide could increase the molar volume of PI. Based on this property, this study successfully prepared low dielectric polyimide resins and meticulously investigated the effect of the rearrangement ratio on the properties of PI, especially the dielectric properties. The results show that the D_k of PI decreases significantly and the glass transition temperature (T_g) increases significantly with the increase of rearrangement ratio. Among them, it is worth mentioning that PBO-40 has the best performance, presenting a low dielectric constant (D_k = 2.54@10 GHz), low dielectric loss (D_f = 0.00585@10 GHz), high heat resistance (T_g = 315 °C, 5% decomposition temperature (N₂) T_d5% = 509 °C) and low water absorption (M_a = 0.65%). In conclusion, this study provides learnable strategies for the design of high-frequency dielectric PIs.