Photosensitive polyimide adhesive sheet
Positive tone Photosensitive Polyimide B-stage sheet which was composed of transparent soluble polyimide, naphthoquinone diazide compound, thermal cross linker and solvent, was developed. We designed new polyimide structure and cross linker suitable for photosensitive polyimide sheet. The photosensitive sheet shows fine pattern formation capability as well as good thermal stability and mechanical properties. It is quite easy to obtain flat surface on topological surface to laminate the photosensitive sheet.
Novel Partial Esterification Reaction in Poly(amic acid) and Its Application for Positive-Tone Photosensitive Polyimide Precursor
We found novel quantitative esterification in poly(amic acid) (PAA) by reacting with N,N-dimethylformamide dialkyl acetals (DFAs). Different alkyl ester was obtained by changing the alkyl group in DFAs. The esterification ratio was determined by amount of DFAs. The reaction proceeds under mild condition without any catalysis. It has not been reported such a kind of quantitative partial esterification before. The partial esterification allowed us to control the solubility of PAA to alkaline solutions. The strict solubility rate control to alkaline solution of PAA was quite important for positive tone photosensitive polyimide (posi PSPI). The partial esterification of PAA gave us a way to strict dissolution control. By using it, we could obtain posi PSPI just mixing with diazonaphthoquinone compound.
Positive Pattern Formation and its Mechanism from Ionic bonded Negative Photosensitive Polyimide
We found positive pattern formation by ionic bonded photo-sensitive polyimide (PSPI). The PSPI is composed of poly(amic acid), photo-reactive tertiary amine (such as N.N-dimethylaminoethylacrylate), and photo-initiator. The PSPI basically has negative photo-sensitivity. However, we found that positive pattern formation from the PSPI when adding a post-exposure bake (PEB) about 120-140 °C. By adding PEB, imidization rate of unexposure area of PSPI is higher than that of exposed area. High imidizaiton of unexposed area of PSPI makes hard to solubule to alkaline solution. The imidization rate difference attributes to glass transition temperature difference between exposed area and unexposed area.