2013 Volume 34 Issue 5 Pages 261-271
Photosensitive polyimides have been utilized as buffer-coat layer between IC chip and encapsulating resin. However, conventional photosensitive polyimides have disadvantages such as necessity of high temperature post-curing after pattern formation due to their use of polyimide precursors, poly(amic acid)s, as polymer components. We have developed a novel mechanism, reaction development patterning (RDP), to give photosensitivity to polyimides and other engineering plastics containing carboxylic-acid-derivative bonds in their main chains. Pattern formation by RDP is based on selective change in solubility of engineering plastics at photo-irradiated (or unirradiated) areas by nucleophilic acyl substitution between carboxylic-acid derivatives in a polymer chain and nucleophiles in a developer during development process. Thus, RDPbased photosensitive polyimides can be obtained from polyimides themselves, and pattern formation from polycarbonates and polyesters is also achieved by applying RDP to these polymers. Here, pattern-forming mechanism of positive- and negative-tone RDPs and their scope of application are described.
