Abstract
Fluorinated aromatic polyimide (FAPI) films with rigid polymer backbones have been prepared by chemical imidization approach. The polyimide films exhibited excellent mechanical properties including elastic modulus of up to 8.4 GPa and tensile strength of up to 326.7 MPa, and outstanding thermal stability including glass transition temperature (Tg) of 346.3–351.6 °C and thermal decomposition temperature in air (Td5) of 544.1–612.3 °C, as well as high colorless transmittance of >81.2% at 500 nm. Moreover, the polyimide films showed stable dielectric constant and low dielectric loss at 10–60 GHz, attributed to the close packing of rigid polymer backbones that limited the deflection of the dipole in the electric field. Molecular dynamics simulation was also established to describe the relationship of molecular structure and dielectric loss.
Highlights
Polymers 2022, 14, 649. https://Aromatic polyimide films have been widely used in the microelectronic manufacturing and packaging industry due to its excellent thermal stability, combined mechanical properties, dimensional stability, chemical resistance and electrical insulating properties [1,2,3,4]
Fluorinated aromatic polyimide films were prepared by a two-step chemical imidization method displayed in Scheme 1. 32.02 g (100 mmol) of TFDB and 282 mL of DMAc were added into a three-neck round-bottom flask under a nitrogen atmosphere
A series of fluorinated aromatic polyimides with different biphenyl group content in polymer backbone by changing the molar ratios of 6FDA/Biphenyltetracarboxylic dianhydride (BPDA) were successfully synthesized by chemical imidization method
Summary
Polymers 2022, 14, 649. https://Aromatic polyimide films have been widely used in the microelectronic manufacturing and packaging industry due to its excellent thermal stability, combined mechanical properties, dimensional stability, chemical resistance and electrical insulating properties [1,2,3,4]. The dielectric constants of polyimides could be reduced by introducing fluorine [5,6,7,8], aliphatic/alicyclic structure [9,10,11], large side groups [12,13,14,15,16] or air [17,18,19,20] into polymer backbones. The copolyimide films showed dielectric constant of 2.56 and dielectric loss of 0.004 at 1 MHz. the glass transition temperatures of the films were lower than 290 ◦ C and no mechanical properties were described. The composite films were brittle, having elongation at breakage of lower than 10%, and no dielectric properties at high frequencies were described
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