LAUSR

Abstract It is highly desirable to combine the solubility of the PI precursor in a non-polluting solvent with the high performance behavior of PIs without sacrificing processability, thermal properties and mechanical properties. In this study, we explored a new strategy based on polycondensation reactions to prepare poly-(amic acid) ammonium salt (PAAS) in aqueous solution. PAAS was synthesized using a mixture of 3,3,4,4-biphenyltetracarboxylic dianhydride and 4,4′-oxydiphthalic anhydride and a mixture of 4,4′-diaminodiphenyl ether and p-phenylenediamine. The molecular weight of PAAS, the inherent viscosity of the PAAS solution, and the thermal and mechanical properties of the obtained PI films were investigated by focusing on the polymer structures and comparing with those of the polymerization in N,N-dimethylacetamide. The PI films produced via the different polymerization methods had almost the same thermal properties. Adhesion properties of flexible copper-clad laminates (FCCLs) which were influenced by the plastic deformation and the interface condition that was investigated using Fourier-transform infrared microspectroscopy, were investigated using the peel strength test. The peel strength of the FCCLs changed little between room temperature and 200 °C, and this indicates that the obtained film that prepolymerized in aqueous solution can potentially be used for FCCLs at high temperature in the microelectronics industry.