A transparent polyimide film, prepared from a copolymerized polyamide acid according to a chemical cyclization method, is provided. The copolymerized polyamide acid requires at least a semi-aromatic polyamide acid, and the semi-aromatic polyamide acid is formed by reacting cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA) and 2,2′-bis(trifluoromethyl)diaminodiphenyl (TFMB). The molar number of dianhydrides of the semi-aromatic polyamide acid is more than 20% of the total molar number of anhydrides of the copolymerized polyamide acid, so that the transparent polyimide film has a light transmittance greater than 80%, a chroma b* less than 5, and a CTE less than 35 ppm/° C.

Curable polyimides and compositions thereof with very good dielectric properties are provided. Prepregs of these compositions laminated with copper foil to prepare copper clad laminates having Tg>150 C and Df<0.0025 are also provided.

The present invention provides a tetracarboxylic acid diester compound shown by the following general formula (1),

##STR00001##

wherein X.sub.1 represents a tetravalent organic group; and R.sub.1 represents a group shown by the following general formula (2),

##STR00002##

wherein the dotted line represents a bond; Y.sub.1 represents an organic group with a valency of k+1; “k” represents 1 or 2; and “n” represents 0 or 1. There can be provided a tetracarboxylic acid diester compound that can give a polyimide precursor polymer soluble in a safe organic solvent widely used as a solvent of a composition and usable as a base resin of a photosensitive resin composition.

The present invention provides a film forming material for lithography comprising a compound having: a group of formula (0A):

##STR00001## and a group of formula (0B):

##STR00002##

wherein each R is independently selected from the group consisting of a hydrogen atom and an alkyl group having 1 to 4 carbon atoms, provided that at least one R is an alkyl group having 1 to 4 carbon atoms.

The present invention provides a siloxane compound having a novel structure, the compound not being reactive with a polyamic acid which is a polyimide precursor. In addition, provided is a polyimide precursor composition having improved storage stability by adding the siloxane compound as an enhancer for adhesion between a polyimide and a substrate made of an inorganic material. According to the present invention, provided is a multifunctional polyimide film having improved adhesiveness with a substrate made of an inorganic material while having improved optically isotropic characteristics and reduced residual stress characteristics with respect to a substrate.

An object of the present invention is to provide a novel photosensitive resin precursor that can be developed with an alkali and ring-closed even at low temperatures, and preferably has excellent thermal properties and excellent electric properties after curing, and also to provide a use application thereof. As means for achieving the object, disclosed are a bismaleimide compound comprising, in one molecule, two partial structures in each of which a carbon atom having a substituent represented by the following formula (A) (wherein Y represents a direct bond or a divalent linking group), and a carbon atom having a hydroxy group are directly bonded to each other, a polymer which is a self-polymer of the bismaleimide compound, and a benzoxazole which is an intramolecular dehydrated ring-closed product of the polymer.

##STR00001##

The present invention has the effect of making it possible to produce 1,1,1-trifluoro-2,2-bisarylethane efficiently by a simple procedure by condensing a mixture of fluoral and hydrogen fluoride with an aryl compound under anhydrous conditions. The purity of the 1,1, 1-trifluoro-2, 2-bisarylethane obtained can be raised by a simple purification method such as crystallization or distillation. The obtained 1,1,1-trifluoro-2,2-bisarylethane can be increased in purity by a simple purification method such as crystallization operation or distillation.

A polyimide which is obtained by a reaction of an aromatic diamine having a 1,1,1-trifluoro-2,2-ethanediyl group (—C(CF.sub.3)H—), as a linkage skeleton, with a tetracarboxylic dianhydride is easily dissolved in an organic solvent and exhibits excellent film forming properties. In addition, the thus-obtained polyimide can be used for an optical film and a display device.

The present disclosure relates to a poly(amide-imide) copolymer in which at least one of an imide repeating unit and an amide repeating unit is substituted with a specific functional group, and a composition and a polymer film comprising the same.

The present invention provides a siloxane compound having a novel structure, the compound not being reactive with a polyamic acid which is a polyimide precursor. In addition, provided is a polyimide precursor composition having improved storage stability by adding the siloxane compound as an enhancer for adhesion between a polyimide and a substrate made of an inorganic material. According to the present invention, provided is a multifunctional polyimide film having improved adhesiveness with a substrate made of an inorganic material while having improved optically isotropic characteristics and reduced residual stress characteristics with respect to a substrate.