A resin sheet is made of a resin composition containing a (A) heat-curable component. The (A) heat-curable component contains a (A1) first maleimide resin. The (A1) first maleimide resin is a maleimide resin having two or more maleimide groups in one molecule, at least a pair of the maleimide groups being bonded by a binding group whose main chain includes four or more methylene groups.

A resin sheet is made of a resin composition containing a (A) heat-curable component. The (A) heat-curable component contains a (A1) first maleimide resin. The (A1) first maleimide resin is a maleimide resin having two or more maleimide groups in one molecule, at least a pair of the maleimide groups being bonded by a binding group whose main chain includes four or more methylene groups.

A resin composition contains a maleimide compound (A) and a phosphorus-containing compound (B). The maleimide compound (A) includes a first maleimide compound (A1) having an alkyl group, of which a carbon number is equal to or greater than six, and/or an alkylene group, of which a carbon number is equal to or greater than six. The phosphorus-containing compound (B) includes a phosphorus-containing compound (B1) having a structure expressed by the following formula (b1), where s indicates an integer falling within a range from 1 to 10, Z indicates either an arylene group or an ester bond expressed by the following formula (b1.1), R.sup.1 to R.sup.3 each independently indicate either a hydrogen atom or a monovalent organic group, and * indicates a bond.

An object is to provide a novel bismaleimide compound. The solution is a bismaleimide compound represented by formula (1):

##STR00001## wherein A.sub.1 represents a direct bond, a divalent linking group represented by formula (1-1), (1-2), or (1-3):

##STR00002## wherein ring a represents a benzene ring or a cyclohexane ring; X represents a direct bond or a divalent linking group; and Z represents a monovalent substituent; or a divalent linking group other than this; at least one of a plurality of A.sub.1s is formula (1-1), (1-2), or (1-3); A.sub.2 represents a divalent linking group that is a residue of a saturated aliphatic dicarboxylic acid compound, a divalent linking group that is a residue of an aromatic dicarboxylic acid compound, or a divalent linking group other than this; and when A.sub.2 is present singly, A.sub.2 is a divalent linking group that is a residue of a saturated aliphatic dicarboxylic acid compound, and when a plurality of A.sub.2s is present, at least one of A.sub.2s is a divalent linking group that is a residue of a saturated aliphatic dicarboxylic acid compound.

In an aspect, a thermosettable composition comprises an imide extended compound and a reactive monomer that is free-radically crosslinkable with the reactive end groups of the imide extended compound to produce a crosslinked network. A thermoset composite can be derived from the thermosettable composition and a multilayer article can include the thermoset composite in the form of a layer. The article can be an antenna, a bond ply, a semiconductor substrate build-up/redistribution layer dielectric film, a circuit board, resin-coated-copper (RCC), or a flexible core.

Resin composition including an epoxy resin, an epoxy resin curing agent, and a polyimide resin including a specified structural unit provide a high yield after patterning.

A compound (A) of the present invention is represented by the formula (1): wherein each R.sub.1 independently represents a group represented by the formula (2) or a hydrogen atom, and each R.sub.2 independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, provided that at least one R.sub.1 is a group represented by the formula (2); and wherein -* represents a bonding hand.

A compound (A) of the present invention is represented by the formula (1): wherein each R.sub.1 independently represents a group represented by the formula (2) or a hydrogen atom, and each R.sub.2 independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, provided that at least one R.sub.1 is a group represented by the formula (2); and wherein -* represents a bonding hand.

A thermosetting resin composition containing a thermosetting resin (A), boron nitride (B), and a dispersant (C) with a pH of 8 or higher.

A thermosetting resin composition containing a thermosetting resin (A), boron nitride (B), and a dispersant (C) with a pH of 8 or higher.