Browse Prior Art Database

Method of Decreasing Optical Losses in Polyimides

IP.com Disclosure Number: IPCOM000103460D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 1 page(s) / 48K

Publishing Venue

IBM

Related People

Feger, C: AUTHOR [+2]

Abstract

Disclosed is a method to avoid inadvertent optical losses (absorption) in photosensitive polyimides (PSPIs) and optical waveguide polyimides and to increase the shelf life of such compounds.

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Method of Decreasing Optical Losses in Polyimides

      Disclosed is a method to avoid inadvertent optical losses
(absorption) in photosensitive polyimides (PSPIs) and optical
waveguide polyimides and to increase the shelf life of such
compounds.

      Photosensitive polyimides (PSPIs) and optical waveguide
polyimides are often synthesized or dissolved in NMP.  In the
presence of water, oxygen and light, however, NMP decomposes forming
light to dark yellow decomposition products.  During the cure of
polymer films cast from such solutions, NMP evaporates as expected so
that, at best, trace amounts can be found after high temperature
cure.  The colored byproducts of NMP, however, do not evaporate.
This is not detrimental in applications where the ultimate optical
absorption of the film produced is of minor concern. However, if the
solutions are used to deposit optical waveguides or photosensitive
polymers where certain absorption characteristics need to be met, the
additional absorption from NMP decomposition products may render a
material useless.  Absorption losses due to NMP decomposition become
worse as the solutions age, even if kept at -4oC.

      Deterioration of the optical characteristics of high
performance polymers caused by NMP decomposition products can be
avoided by substituting NMP with another solvent, e.g. q
-butyrolactone (GBL).  Using this solvent it was, for instance,
possible to lower the optical losses measured at 632 nm in a
polyimide...