Novel aqueous development of polyimide patterning based on tert-ammonium side chains

To solve the problem of aqueous development of photosensitive polyimide (PSPI) in the advanced packaging field at this stage through the main chain structure design which leads to its poor thermal and mechanical properties, this paper proposes a new structural design method based on the side-chain-type polyamide ester (PAE, PSPI precursor) to achieve aqueous development of PSPI. The method introduces a water-soluble tertiary ammonium salt group into the PAE side chain to obtain a water-soluble side-chain polyamide ester, which in combination with the solvation inhibitor diazonaphthoquinone (DNQ), can achieve high-resolution aqueous development patterning (up to 1 μm). The tertiary ammonium salt-containing side chain is completely removed in the imidisation stage, which does not affect the properties of the main chain of PSPI itself. The method was applied to three PSPIs with different rigid structures, and good thermal and mechanical properties of the PSPIs were obtained while aqueous development patterning was achieved, which proved the practicality of the method.