Amine functionalized SBA-15/terpolyimide composites with low dielectric constant

Abstract

Polyimides with low dielectric constants are important raw materials for the fabrication of flexible printed circuit boards and other microelectronic applications. As creation of voids in polyimide matrix could decrease the dielectric constant, in this study mesoporous SBA-15, synthesized hydrothermally, was functionalized with 3-aminopropyltriethoxysilane (APTS) and incorporated (2–10 %) into terpolyimide. The APTS functionalized SBA-15 was mixed with 4,4′-oxydianiline in the synthesis of terpoly(amic acid) using 3,3′,4,4′-biphenyldianhydride (BPDA), 3,3′,4,4′-oxydiphthalicdianhydride (ODPA) and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and subsequently stage-cured to obtain APTS-SBA-15/terpolyimide composites. The asymmetric and symmetric vibrations of imide O=C–N–C=O groups of APTS-SBA-15/terpolyimide composites showed their peaks at 1772 and 1713 cm−1. The dielectric constant of APTS-SBA-15/terpolyimide composite decreased with the increase in APTS-SBA-15 loading from 2 to 8 %, and remained same at 10 %, and at 8 and 10 % loading it was 2.42. However, there was agglomeration of mesoporous silica in APTS-SBA-15 (8 and 10 %)/terpolyimide composites. Hence, APTS-SBA-15 (6 %)/terpolyimide with dielectric constant (2.51), tensile strength (100 MPa), tensile modulus (3.3 GPa), percentage elongation (7.3) and high thermal stability (>540 °C) could be suitable for application in microelectronics such as tape automated bonding and flexible printed circuits. Therefore, polyimide composites carrying optimum amount of mesoporous materials can be expected to have adequate thermal and mechanical properties with significantly low dielectric constant.