| abstract |
An intimate polyimide blend, prepared by chemical conversion, containing from 25 to 50 weight % of a first polyimide derived from 90 to 100 mole % of 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 0 to 10 mole % of pyromellitic dianhydride and p-phenylenediamine and from 50 to 75 weight % of a second polyimide derived from pyromellitic dianhydride, from 20 to 50 mole % of p-phenylenediamine and from 50 to 80 mole % of 4,4'-diaminodiphenylether. The polyimide blend provides blister free films having high modulus and low thermal expansion coefficients for use in electronics applications. |