New screen-printable polyimide for IC devices

In order to develop a screen-printable polyimide paste, the structures, properties, and ratios of three major paste components (filler, binder, and solvent) were studied, and a film-forming strategy was established. This strategy comprises a novel type of polyimide particle filler, which can be dissolved in the binder and the solvent under the curing condition. A screen-printable polyimide paste was developed using this strategy. This paste gives uniform film with better mechanical properties than conventional polyimide paste, which comprises an insoluble polyimide particle filler. The effect of the solubility parameter of the solvent on mask swelling and moisture resistance was also examined. It was also examined. It was found that a lactone with a solubility parameter value of 18~20 (MJ/m³)^1/2 is suitable as a paste solvent. The paste affords uniform pinhole-free polyimide films with good mechanical properties. As the mask swelling is low, the lifetime of stencil is longer than that of conventional pastes