Ube Industries, Inc.

Toshihiro Inaike

Shuji Yamamoto

Toshihiro Inoue

Katsuhiko Ushimi

Hiroshi Itatani

Shunji Ohe

Kazunori Otsuka

An aromatic polyimide composition usable for producing shaped articles, for example, films, or as varnish, lacquer, or bonding agent, comprises a high molecular weight aromatic polyimide resin which is a polycondensation-imidization product of an aromatic tetracarboxylic acid component comprising 50 molar % or more of 3,4,3',4'-biphenyltetracarboxylic acid, anhydride, salt, or ester with an aromatic diamine component including 50 molar % or more of 4,4'-diaminodiphenylether, and which is dissolved in a mixed solvent consisting essentially of 10% by weight or more of a first solvent component selected from naphthol and resorcin and the balance of a second solvent component selected from phenol and cresols.

Aromatic polyimide composition comprising mixed solvent

An aromatic polyamic acid solution composition useful as an electrically insulating varnish, comprises (1) an aromatic polyamic acid which is a polymerization product of (A) a tetracarboxylic acid component containing at least 80 molar % of the sum of (a) a first acid ingredient consisting of 3,3',4,4'-biphenyltetracarboxylic dianhydride and (b) a second acid ingredient consisting of at least one member selected from the group consisting of pyromellitic dianhydride, and 3,3'4,4'-benzophenone tetracarboxylic dianhydride, the molar ratio of the first acid ingredient to the second acid ingredient being in the range of from 30:70 to 75:25, with (B) an amine component consisting of at least one aromatic amine in a molar ratio of the tetracarboxylic acid component to the amine component of from 97:100 to 103:100, and which polymeric acid has a logarithmic viscosity number of from 0.1 to 1.5 determined in a concentration of 0.5 g/100 ml in N-methyl-2-pyrrolidone at a temperature of 30.degree. C., and dissolved in a concentration of from 5% to 40% by weight in (2) an organic polar solvent.

Wholly aromatic polyamic acid solution composition

A method for removal of curling of a circuit printable flexible substrate comprising a metal foil and a film layer of an aromatic polyamideimide or an aromatic polyimide formed by coating on the said metal foil a solution of an aromatic polyamideimide, an aromatic polyimide precursor or an aromatic polyimide, and drying the coated solution layer to setting, whose curling is produced to direct the metal foil surface to face outside, which comprises sliding under tension the curled circuit printable flexible substrate on a curved surface of a bar having a curvature radius of 0.5-25 mm, at which the substrate is turned back at a turning angle of not less than 90.degree., placing the metal foil layer in contact with the bar, at a temperature of not higher than 80.degree. C. A method employing two such bars is also disclosed.

Method for removal of curling of circuit printable flexible substrate

An aromatic imide polymer laminate material usable as a flexible circuit board substrate is produced by the process comprising coating a surface of a metallic foil with a solution of an aromatic imide polymer comprising at least 90 molar % of recurring unit of the formula (I): ##STR1## wherein R is a symmetrical bivalent aromatic radical having no substituent, and dissolved in a solvent consisting essentially of at least one phenolic compound; and heat drying the resultant solution layer to form an aromatic imide polymer solid layer firmly bonded directly to the metallic foil.

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Ichihara, Japan

Toshihiro Inaike