Polyimide solvent cast films having a low coefficient of thermal expansion and method of manufacture thereof

A method of making a solvent cast polyimide film, comprising:

• casting a polyamic acid composition comprising structural units derived from polymerization of a dianhydride component comprising a dianhydride selected from the group consisting of 3,4′-oxydiphthalic dianhydride, 3,3′-oxydiphthalic dianhydride, 4,4′-oxydiphthalic dianhydride, and a combination thereof, with a diamine component comprising 4,4′-diaminodiphenylsulfone and p-phenylene diamine and wherein the diamine component comprises greater than or equal to 10 mole % of 4,4′-diaminodiphenyl sulfone, based on the total moles of the diamine component onto a substrate to form a film;
• heating the cast film for a time and at a temperature effective to remove the solvent and to form a solvent cast polyimide film having a coefficient of thermal expansion of less than 60 ppm/° C. as measured over 30 to 200° C., and a thickness from 0.1 to 125 micrometers;
• and
• processing the solvent cast polyimide film to reduce the coefficient of thermal expansion of the film to below 35 ppm/° C. (as measured over 30 to 200° C.) by biaxially stretching the solvent cast polyimide film.

A solvent cast film, comprising:

• a thermoplastic polyetherimide comprising structural units derived from the polymerization of a dianhydride component comprising a dianhydride selected from the group consisting 3,4′-oxydiphthalic dianhydride, 3,3′-oxydiphthalic dianhydride, 4,4′-oxydiphthalic dianhydride, and combinations thereof, with a diamine component comprising 4,4′-diaminodiphenylsulfone and p-phenylene diamine, wherein the diamine component comprises greater than or equal to 10 mole % of 4,4′-diaminodiphenyl sulfone, based on the total moles of the diamine component;
• wherein the polyimide has a glass transition temperature from 190° C. to 400° C.;
• wherein the film is solvent cast and has
• a coefficient of thermal expansion of less than 60 ppm/° C. as measured over a temperature of 30 to 200° C.,
• a thickness from 0.1 to 250 micrometers, and
• less than 5% residual solvent by weight;
• wherein the film has a coefficient of thermal expansion that is within ±20 ppm/° C. of the coefficient of thermal expansion of copper, silicon, aluminum, gold, silver, nickel, a glass, a ceramic, or a polymer;
• and
• wherein the solvent is selected from the group consisting of N,N-dimethylacetamide, N,N-dimethylformamide, N-methylpyrrolidinone, dimethylsulfoxide, sulfolane, tetrahydrofuran, benzophenone, cyclohexanone, phenol, o-cresol, p-cresol, m-cresol, phenol, ethylphenol, isopropylphenol, t-butylphenol, xylenol, mesitol, chlorophenol, dichlorophenol, phenylphenol, a monoalkyl ether of ethylene glycol having from 1 to about 4 carbon atoms in the alkyl group, a monoalkyl ether of diethylene glycol having from 1 to about 4 carbon atoms in the alkyl group, a monoaryl ether glycol, a monoaryl ether of propylene glycol, tetramethylurea, phenoxy ethanol, propylene glycol phenyl ether, anisole, veratrole, o-dichlorobenzene, chlorobenzene, trichloroethane, methylene chloride, chloroform, pyridine, N-cyclohexylpyrrolidinone, ethyl lactate, an ionic liquid, and a combination comprising at least two of the foregoing solvents.

A solvent cast film comprising

• a thermoplastic polyetherimide comprising structural units derived from polymerization of 4,4′-oxydiphthalic dianhydride, p-phenylene diamine and 4,4′-diaminodiphenylsulfone;
• wherein the polyimide has a glass transition temperature from 190° C. to 400° C.;
• wherein the film is solvent cast and has
• a coefficient of thermal expansion of less than 30 ppm/° C. as measured over a temperature of 30 to 200° C.,
• a thickness from 0.1 to 250 micrometers, and
• less than 5% residual solvent by weight;
• and
• wherein the film has less than 15 molar % of biphenyltetracarboxylic acid or its dianhydride or its ester.