A strategy for the preparation of low dielectric FGQD/PSPI composite films in wafer-level packaging

Advancement of wafer-level packaging (WLP) has heightened the requirements for photosensitive polyimide (PSPI) materials, where the low dielectric property is a key element to realize high frequency communication. Herein, a poly(amidate) (PAE) was prepared using Pyromellitic Dianhydride, 4,4’-diaminodiphenyl ether, and hydroxyethyl methacrylate as the photosensitive group. Specifically, the fluorinated graphene quantum dots (FGQD) was introduced into the PAE resin by in situ polymerization, and the prepared composite films of photosensitive polyimide-fluorinated graphene quantum dots (PSPI-FGQD) showed excellent dielectric constants and other comprehensive properties. Compared with pure PSPI, the dielectric constant of PSPI-FGQD decreases from 3.8 to 3.0 at 1 MHz; the tensile strength increases from 84.5 to 110.1 MPa, the elongation at break raises from 5.24 % to 17.3 %, and the Young's modulus increases from 2.68 GPa to 2.88 GPa. The glass transition temperature ( T g ) is also increased to 420 °C with the introduction of FGQD. Apart of these, the fine patterning ability was observed for the FGQD/PSPI composite film, achieving a high photolithography resolution of 10 μm (L/S). To conclude, the preparation method of low dielectric FGQD/PSPI materials has promising potential applications in advanced packaging.