Provided are a resin composition having especially good compatibility and having dielectric properties (low dielectric constant and low dielectric dissipation factor) in a high frequency range, high adhesion to conductor, excellent heat resistance, high glass transition temperature, low thermal expansion coefficient and high flame retardancy, and a prepreg, a laminate and a multilayer printed wiring board using the resin composition. Specifically, the resin composition contains (A) a polyphenylene ether derivative having an N-substituted maleimide structure-containing group and a structural unit represented by the following general formula (I) in one molecule, (B) at least one thermosetting resin selected from the group consisting of epoxy resins, cyanate resins and maleimide compounds, and (C) a styrenic thermoplastic elastomer:

##STR00001## wherein R.sup.1 each independently represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms, or a halogen atom, and x represents an integer of 0 to 4.

Provided are a thermosetting resin composition having especially good compatibility and having dielectric properties (low dielectric constant and low dielectric dissipation factor) in a high frequency range, high adhesion to conductor, excellent heat resistance, high glass transition temperature, low thermal expansion coefficient and high flame retardancy, and a prepreg, a laminate and a multilayer printed wiring board using the resin composition. Specifically, the thermosetting resin composition contains (A) a polyphenylene ether derivative having an N-substituted maleimide structure-containing group and a structural unit represented by the following general formula (I) in one molecule, (B) at least one thermosetting resin selected from the group consisting of epoxy resins, cyanate resins and maleimide compounds, and (C) a phosphorus flame retardant:

##STR00001##

wherein R.sup.1 each independently represents an aliphatic hydrocarbon group having 1 to 5 carbon atoms, or a halogen atom, and x represents an integer of 0 to 4.

The present disclosure provides a modified allyl compound, and a modified bismaleimide prepolymer. The modified allyl compound is represented by formula (1), has a cyclopentadiene structure represented by formula (2), and contains a benzene ring or a benzene ring substituted with a linear alkane of lower polarity.

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),

Y.sub.1.sub.nRf).sub.k (2)

wherein the dotted line represents a bond; Y.sub.1 represents an organic group with a valency of k+1; Rf represents a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms or an aromatic group in which a part or all of hydrogen atoms is/are substituted with a fluorine atom(s); k represents 1, 2, or 3; 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 negative photosensitive resin composition.

Provided are a heat-curable maleimide resin composition suitable for use in a substrate, and whose cured product has an excellent high-temperature property due to its high glass-transition temperature, an excellent dielectric property and an excellent dimension stability; and an uncured and cured resin films comprised of such composition, and having an excellent handling property. The heat-curable maleimide resin composition contains: (A) a maleimide resin having a number average molecular weight of not lower than 3,000; (B) an organic compound having, in one molecule, at least one allyl group and at least one isocyanuric ring; and (C) a reaction initiator.

Provided are a heat-curable maleimide resin composition suitable for use in a substrate, and whose cured product has an excellent high-temperature property due to its high glass-transition temperature, an excellent dielectric property and an excellent dimension stability; and an uncured and cured resin films comprised of such composition, and having an excellent handling property. The heat-curable maleimide resin composition contains: (A) a maleimide resin having a number average molecular weight of not lower than 3,000; (B) an organic compound having, in one molecule, at least one allyl group and at least one isocyanuric ring; and (C) a reaction initiator.

A modified bismaleimide resin is made by modify bismaleimide with aromatic diamine that contains fluoro substituents through chain-growth polymerization; and modified bismaleimide resin is excellent in physical properties including a low dielectric constant Dk (3 GHz) less than 3.0, a dissipation factors (3 GHz) less than 0.02, a low resin water absorptivity ranging from 0.21% to 0.33% and an excellent processability, and is particularly suited for producing a copper clad laminate that is required to have dielectric constant Dk (3 GHz) less than 3.

A resin sheet is made using a resin composition containing a thermosetting component (A) and a thermally conductive filler (C). The thermosetting component (A) contains a maleimide resin. A thermal diffusion rate of the thermally cured resin sheet is 1.010.sup.6 m.sup.2/s or more. When a cross section (P) of the resin sheet taken by cutting the resin sheet in a vertical direction to a surface of the resin sheet is observed in an area (P1), a condition represented by a numerical formula (F1) below is satisfied, the area (P1) being defined by a square whose sides are four times as large as a thickness of the resin sheet and including two surfaces of the resin sheet,
0.25Ld/Lt1(F1) where Ld is a vertical length of a filler particle having a largest cross-sectional diameter in the vertical direction of the thermally conductive filler (C), and Lt is a length of the resin sheet.

A substance which makes it possible to selectively mask according to the substrate surface material. A polymer film-forming composition for selectively forming a polymer film on a region (R-I) of a substrate which has the region (R-I), the surface of which includes a metal (I), and a region (R-II), the surface of which includes a material (II) which differs from the metal (I), the polymer film-forming composition including a radical generator (A) and a radical-equipped reactive compound (B); and a selective polymer film formation method for forming a film of the polymer film-forming composition on the surface of the substrate.

Provided is a thermosetting resin composition that contains a high dielectric constant material and that can suppress, in producing a cured product thereof, generation of outgas, decrease in heat resistance, and decrease in peel strength. Also provided are a prepreg, a resin film, a laminate, a printed wiring board, an antenna device, an antenna module, and a communication device obtained by using the thermosetting resin composition. The thermosetting resin composition is, specifically, a thermosetting resin composition containing (A) a thermosetting resin and (B) at least one high dielectric constant inorganic filler selected from the group consisting of a titanium-based inorganic filler and a zircon-based inorganic filler, the thermosetting resin composition further containing (C) a resin having 3% by mass or more of an acidic group in an amount of 1 part by mass or more with respect to 100 parts by mass of the component (B).