Bulk side-based polyimide based on polyhedral oligomeric silsesquioxane cross-linking: Towards lower dielectric constant and better mechanical property

The synthesis of a low dielectric constant polyimide (PI) with a polyhedral oligomeric silsesquioxane (POSS) cross-linked structure is presented. A non-planar conjugated diamine monomer (FSNH₂) with two -CH=CH₂ reactive groups was first synthesised in a two-step process, and then two polyimides were synthesized by PSS-Octavinyl (OVPOSS) substituted, FSNH₂ and dianhydride. OVPOSS cross-linked polyimides have good thermal stability and low dielectric constant. 6FDA-FSNH₂-OVPOSS(6FPI-3) can reach a minimum dielectric constant of 2.08 (10⁸ Hz) and a dielectric loss of 0.008 (10⁸ Hz). In addition, the cross-linked structure of the OVPOSS and polyimide chains prevents the agglomeration of OVPOSS to a certain extent and improves the tensile strength and elongation at break of the polyimides, which has great application potential in large-scale integrated circuits.