Low dielectric and thermally stable hybrid ternary composites of hyperbranched and linear polyimides with SiO2

A hydroxyl-terminated hyperbranched polyimide was synthesized via the A(2) + B-3 reaction between dianhydride and triamine monomers. The hydroxyl groups at the peripheral positions were then introduced by modification of the anhydride end groups via a reaction with 4-aminophenol. Based on the hydroxyl-terminated hyperbranched polyimide, HBPIBPADA-TAP(OH), we successfully fabricated hybrid ternary composites, which were comprised of a linear polyimide (PI6FDA-APB), HBPIBPADA-TAP(OH), and an inorganic SiO2 component. The material was designed to satisfy the requirement for cutting-edge insulators with a low dielectric constant and a high thermal stability. Because of the appropriate choice of the hybrid ternary composite systems with HBPIBPADA-TAP(OH) and inorganic silica, it is sensible to improve the dielectric properties and thermal resistant properties of unary systems or improve the disadvantages of the dielectric and optical properties of binary systems. For an optimized composition, the dielectric constant (D-k) of the PI6FDA-APB-HBPIBPADA-TAP(OH)-30%-SiO2-20% composite reaches the lowest value of 2.24 at 100 kHz. Research also showed that the optical transparency is significantly improved with the increase of the HBPIBPADA-TAP(OH) content in the composite. Compared with the binary linear PI (6FDA-APB)-SiO2 composite, the transmittance increases from 1% to 75% at the wavelength of 450 nm. The incorporation of SiO2 can preserve the good thermal properties of the hybrid composites containing HBPIBPADA-TAP(OH). By adding 10% of HBPIBPADA-TAP(OH) to the PI6FDA-APB-SiO220% system, the coefficient of thermal expansion of the hybrid ternary composite is 20.9 ppm degrees C-1 in the temperature range from 100 to 150 degrees C, which is significantly lower than that of the linear polyimide (37.1 ppm degrees C-1 for PI6FDA-APB). Because of these optimized properties, hybrid ternary composites have the potential for use in applications in the micro-electronic insulator fields, such as interlayer dielectrics of advanced electronic devices.