Low-$k$ cross-linked polyimide for microelectronic packaging application

Polyimide (PI) film is considered to be an ideal packaging material due to its excellent comprehensive properties. However, the traditional PI has a relatively high dielectric permittivity (k=3.0 ~ 3.4), which cannot meet the current requirements in the field of microelectronic packaging (k <; 2.5). In this work, Tris(4-aminophenyl) amine (TPA) was used the cross-linking agent to combine with biphenyl-3,3',4,4'-tetracarboxylic dianhydride (BPDA) and 1,4-Bis(4-amino-2-trifluoromethylphenoxy) benzene (6FAPB) by in-situ polymerization for the purpose of obtaining cross-linked low-dielectric polyimide. And the influences of cross-linking agent ratio on the comprehensive properties of PI were studied. The results showed that under a certain loading of TPA, the dielectric permittivity of the PI gradually decreased with the incremental crosslinking agent content. When the molar ratios of amino groups in TPA and 6FAPB was 1:9, the dielectric properties of the cross-linked PI can be minimized, with the lowest value of 1.86 (10⁷ Hz). In addition, the obtained cross-linked polyimide had good thermal stability. It has broad development prospects in the field of microelectronic packaging and integrated circuits in the future.