Synthesis and Characterization of Aromatic Base Polymers with Low Dielectric Constant

Aromatic polymers, such as poly(aryl ether)s, polyimides, have been used as dielectric materials for microelectronics for decades. In recent years, electronic devices’ working frequency reaches GHz bands, and it is believed that requirement of transmitting lager amount of information will force microelectronics operating in a higher frequency in the future. For such high frequency demand, low dielectric constant with high thermal performances materials are in need for next generation of communication. Therefore, in this thesis we explore new aromatic polymers containing low dielectric constant with intrinsic excellent thermal performances. In chapter 2, The cross-linked poly(2,6-DMP95-co-2,6-DDP5) was prepared by oxidative coupling polymerization of 2,6-DMP with 2,6-DDP, followed by the reaction with 4,4’-methylenebis[2,6-bis(methoxymethyl)]phenol (MBMP) as a cross-linking agent. The cross-linked polymer exhibited a good thermal stability as well as a high glass transition temperature. The dielectric constant and dissipation factor of cross-linked polymer were 2.6 and 0.004 at 10 GHz, respectively. Moreover, a flexible double layer copper clad laminate based on the cross-linked polymer composite was successfully prepared, indicating their potential applications in high-speed and high-frequency electrical applications. In chapter 3, oxidative coupling was used to obtained relative high molecular weight poly(2,6-dihydroxy-1,5-naphthalene). Furthermore, a series of poly(2,6-dialkoxy-1,5-naphthalene)s with different length of alkoxy side chain were synthesized. Out of aromatic geometry and highly rigidity of naphthalene backbone, the synthesized polymers possessed high thermal stability with Td above 360oC, and showed no Tg from 30oC to 300oC. The low e constant of these polymers are caused by a large dihedral angle between the neighboring naphthalene rings, resulting in a large free volume. ε of poly(2,6-dibutoxy-1,5-naphthalene) (PDBN), poly(2,6-dihexoxy-1,5- naphthalene) (PDHexN), and poly(2,6-dicyclohexyl-methoxy- 1,5-naphthalene) (PCHMN) were estimated as 2.65, 2.81, and 2.79 at 10GHz, respectively.