M. Berrada et al., NOVEL NEGATIVE-TYPE SOLUBLE PHOTOSENSITIVE POLYIMIDES - SYNTHESIS ANDCHARACTERIZATION, Chemistry of materials, 8(5), 1996, pp. 1029-1034
In the present paper, we describe the synthesis and characterization o
f a novel negative-type soluble photosensitive polyimide (PSPI). A gro
up of new photosensitive polyimides has been prepared by condensation
of dianhydrides bearing photoreactive ester groups and aromatic diamin
es in N-methylpyrrolidone (NMP), followed by chemical imidization usin
g acetic anhydride without acid accepters such as pyridine or triethyl
amine. Thus, the starting monomer used in the synthesis of a commercia
l aromatic polyimide has been chemically modified with four different
photosensitive groups (chlorine-free synthesis). All the intermediates
as well as the resulting polymers have been characterized. The PSPI e
sters were found to be soluble in N-alkyl-substituted amides. Their ir
radiation with UV light induces cross-linking of the photoreactive est
er groups. These systems change from being weakly to being heavily cro
ss-linked during irradiation and do not swell during development. The
remaining PSPI esters do not require thermal imidization because they
are already imidized, and shrinkage is about 20% due to volatilization
of photoreactive groups.