Design of long-chain branched copolyesters and manufacture as well as physical properties of their extrusion films

A long-chain branched copolyester (i.e. p-hydroxybenzoic acid (HBA)/2-hydroxy-6-naphthoic acid (HNA)/1,1,1-tris(4-hydroxyphenyl)ethane (THPE) copolyester) and its extrusion film with superior physical properties to commercial Ticona A950 and Vecstar CTZ have been manufactured by the design of appropriate prescriptions, T-Die extrusion, and thermal treatment of crystal transformation. In order to investigate the fabricating feasibility for flexible copper clad laminate (FCCL) of fourth/fifth generation long-term evolution (4G/5G LTE), we have also agglutinated lab-made copolyester extrusion film with the copper foil by hot compression. Experimental results manifest that lab-made copolyester extrusion film is a highly potential FCCL substrate of 4G/5G LTE because its thickness, dielectric constant (Dk), dielectric loss (Df), hygroscopicity, yellowness index (YI), antistatic capability, flammability, melting temperature (Tm), coefficient of thermal expansion (CTE), and peel strength to copper foil are 50 μm, 2.90, 0.00140, 0.04%, 2.7, 6.5 × 109 Ω/□, UL-94 V0, 305 °C, 24.8 ppm/°C, and 29.9 lb/in, respectively.