A resin composition having an adhesive property in a high temperature range that is estimated during soldering, and flux using this resin composition, a flux residue of which is washable. The resin composition contains a hydroxyl carboxylic acid having two or more carboxyl groups and a hydroxyl group in its molecule and a thermosetting resin in a ratio of 1:3 or more and 1:7 or less. Further, the flux contains the hydroxyl carboxylic acid having two or more carboxyl groups and a hydroxyl group in its molecule in an amount of 8.5% by mass or more and 16% by mass or less, and a thermosetting resin in an amount of 50% by mass or more and 60% by mass or less, wherein a ratio between the hydroxyl carboxylic acid and the thermosetting resin is 1:7 or less.

The present invention provides an active ester resin containing a phosphorus atom capable of providing a cured product having all of flame retardancy, heat resistance, and dielectric characteristics, an epoxy resin composition containing the same as a curing agent, a cured product thereof, a prepreg, a circuit board, and a build-up film. The active ester resin containing a phosphorus atom has Structure (I) in which a structural unit () in which a plurality of aromatic nuclei (X) are connected through an alicyclic hydrocarbon group is connected with another structural unit () through an arylene dicarbonyloxy group, and, at least one of the aromatic nuclei (X) present in the resin has a structural site (Y) represented by any one of the following Structural Formulas (y1) to (y4) as a substituent on the aromatic nucleus. ##STR00001##

A resin composition contains an epoxy compound and a curing agent. The epoxy compound includes a phosphorus-containing epoxy compound having a phosphorus atom in its molecule. The curing agent includes a phosphorus-containing acid anhydride having a phosphorus atom and an acid anhydride group in its molecule.

The instant disclosure relates to phosphorus-containing compounds that can be used to form flame retardant phosphorus-containing resins, and also can serve as a hardener for a flame retardant epoxy resin compositions. In particular, the phosphorus-containing compounds are modified with acyloxy groups (O(CO)R), as shown below. Incorporation of the acyloxy groups results in resins that are water resistant and exhibit improved dielectric properties. ##STR00001##

Epoxy curing agents are disclosed having an epoxy curing agent comprising at least one room temperature ionic liquid salt, the room temperature ionic liquid salt being a reaction product of (a) at least one polyalkylene polyamine compound represented by formula (I): ##STR00001##
wherein x, y, and z are integers of 2 and 3, m and n and integers of 1-3; and (b) an organic acid having pKa (the negative of the logarithm of the acid dissociation constant) less than 6. The liquid salt is a stable liquid at a temperature greater than 15 C. Curable epoxy-based compositions including the curing agent and articles formed by the curable epoxy-based compositions are also disclosed.

The instant disclosure relates to phosphorus-containing compounds that can be used to form flame retardant phosphorus-containing resins, and also can serve as a hardener for a flame retardant epoxy resin compositions. In particular, the phosphorus-containing compounds are modified with acyloxy groups (O(CO)R), as shown below. Incorporation of the acyloxy groups results in resins that are water resistant and exhibit improved dielectric properties. ##STR00001##

A protective film forming composition for forming a protective film that protects an inorganic film formed on a surface of a semiconductor substrate against wet etching, the protective film forming composition including: a polymer having a partial structure represented by Formula (A) and a solvent.

##STR00001##

In Formula (A), R.sub.1 is an (n+2)-valent organic group, R.sub.2 is a hydrogen atom or an alkyl group having 1 to 13 carbon atoms which may be substituted with a substituent, n is 1 or 2, and * is a bond.

A protective film forming composition which has good mask (protection) function against a wet etching liquid and a high dry etching rate during processing of a semiconductor substrate and also has good coverage even in a stepped substrate, and from which a flat film can be formed due to a small difference in film thickness after being embedded; a protective film produced using said composition; a substrate with a resist pattern; and a method for manufacturing a semiconductor device. This protective film forming composition against a wet etching liquid for semiconductors contains an organic solvent and a polymer having, at a terminal thereof, a structure containing at least one pair of two adjacent hydroxyl groups in a molecule. The structure containing two adjacent hydroxyl groups in a molecule may be 1,2-ethanediol structure (A).

Epoxy resin composition comprising component (A): an epoxy resin, component (B): at least one curing agent selected from the group consisting of a triazine skeleton-containing phenol-based curing agent, an active ester-based curing agent, and a cyanate ester-based curing agent, and component (C): a compound represented by a predetermined chemical formula, preferably an imidazole compound.