Compositions for production of electronic coatings

Claim 1

A method of forming a coating upon a planar substrate which comprises (a) applying to the central region of the planar surface a partially fluorinated polyamic acid composition, (b) rotating the substrate at a speed sufficient through centrifugal effect to cause the composition to flow outwardly toward the perimeter of the surface and form a substantially uniform liquid coating thereon, and (c) drying and curing the coating by heating the same to suitable elevated temperatures; said composition comprising a solution of (i) a 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride/2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane polyamic acid polymer having an inherent viscosity in the range of about 0.2 to about 1.5 dL/g (as measured in N-methylpyrrolidone at 25° C. at a concentration of 0.5 g/dL) in (ii) a solvent containing at least 40% by weight of one or more liquid aromatic hydrocarbons having a boiling point of at least about 110° C. and at least 5% by weight of one or more dipolar aprotic solvents having a boiling point of at least about 150° C., such that the solution (a) contains on a weight basis from about 5% to about 40% of such polyamic acid and (b) does not undergo precipitate formation during spin coating in an atmosphere of up to at least about 55% relative humidity; said method being further characterized in that it is conducted in an atmosphere having a relative humidity that does not result in such precipitate formation during the rotation in (b).

Claim 2

A method of forming a coating upon a planar substrate which comprises (a) applying to the central region of the planar surface a partially fluorinated polyamic acid composition, (b) rotating the substrate at a speed sufficient through centrifugal effect to cause the composition to flow outwardly toward the perimeter of the surface and form a substantially uniform liquid coating thereon, and (c) drying and curing the coating by heating the same to suitable elevated temperatures; said composition comprising a solution of (i) a 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride/2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane polyamic acid polymer having an inherent viscosity in the range of about 0.2 to about 1.5 dL/g (as measured in N-methylpyrrolidone at 25° C. at a concentration of 0.5 g/dL) in (ii) a solvent containing at least 40% by weight of one or more liquid aromatic hydrocarbons having a boiling point of at least about 110° C. and at least 5% by weight of one or more dipolar aprotic solvents having a boiling point of at least about 150° C., such that the solution (a) contains on a weight basis from about 5% to about 40% of such polyamic acid and (b) does not undergo precipitate formation during spin coating in an atmosphere of up to at least about 55% relative humidity; said method being further characterized in that it is conducted in an atmosphere having a relative humidity that does not result in such precipitate formation during the rotation in (b).