A resin composition of the present invention is a resin composition containing a bismaleimide compound (A) containing a constituent unit represented by the following formula (1), and maleimide groups at both ends of the molecular chain, at least one resin or compound (B) selected from the group consisting of a maleimide compound other than the bismaleimide compound (A), a cyanate compound, a benzoxazine compound, an epoxy resin, a carbodiimide compound, and a compound having an ethylenically unsaturated group, and a photo initiator (C):

##STR00001##

wherein R.sub.1 represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms; R.sub.2 represents a linear or branched alkylene group having 1 to 16 carbon atoms, or a linear or branched alkenylene group having 2 to 16 carbon atoms; each R.sub.3 independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 16 carbon atoms, or a linear or branched alkenyl group having 2 to 16 carbon atoms; and each n independently represents an integer of 1 to 10.

A resin composition of the present invention contains: a maleimide compound (A) having a maleimide functional group equivalent of 300 g/eq. or more, and a transmittance of 1% or more at a wavelength of 405 nm (h-line); a maleimide compound (B) having a maleimide functional group equivalent of less than 300 g/eq.; and a photo initiator (C) having an absorbance of 0.1 or more at a wavelength of 405 nm (h-line).

A method of fabricating a printed wiring board (PWB) includes etching traces to carry direct current (DC) on a first surface of a first epoxy-based layer. The first epoxy-based layer includes radio frequency (RF) absorber material. The method also includes arranging a second epoxy-based layer. The second epoxy-based layer includes the RF absorber material and includes a first surface in contact with the first surface of the first epoxy-based layer such that the traces are sandwiched between the first epoxy-based layer and the second epoxy-based layer.

The present invention relates to provision of a photosensitive resin composition containing (A) a photopolymerizable compound having an ethylenically unsaturated group and an acidic substituent, and (B) a photopolymerization initiator, wherein at least one of the components contained in the photosensitive resin composition is a component including a dicyclopentadiene structure; a photosensitive resin film using the foregoing photosensitive resin composition; a printed wiring board and a method for producing the same; and a semiconductor package.

The present invention relates to a resin composition comprising a maleimide compound having a saturated or unsaturated divalent hydrocarbon group and a divalent group having at least two imido bonds; and a catalyst comprising at least one selected from the group consisting of an imidazole compound, a phosphorus compound, an azo compound and an organic peroxide.

The present invention relates to provision of a photosensitive resin composition, a photosensitive resin composition for photo via formation, and a photosensitive resin composition for interlayer insulating layer, each of which is excellent in both photosensitive characteristics and strippability from a support film. In addition, the present invention relates to provision of a photosensitive resin film and a photosensitive resin film for interlayer insulating layer, each of which is composed of the aforementioned photosensitive resin composition. Furthermore, the present invention relates to provision of a multilayer printed wiring board and a semiconductor package, and to provision of a method for producing the aforementioned multilayer printed wiring board. Specifically the photosensitive resin composition is a photosensitive resin composition containing (A) a photopolymerizable compound having an ethylenically unsaturated group, (B) a photopolymerization initiator, and (C) a thermosetting resin, wherein the photopolymerizable compound (A) having an ethylenically unsaturated group includes (A1) a photopolymerizable compound having an acidic substituent and an alicyclic structure together with an ethylenically unsaturated group; and further, the thermosetting resin (C) includes (C1) a thermosetting resin having an alicyclic structure, and the content of the component (C1) is 10 parts by mass or more based on 100 parts by mass of the component (A).

A printed circuit board includes: an insulating layer including an insulating resin and first fillers dispersed in the insulating resin; and a wiring layer disposed on the insulating layer. The first filler includes a core, and a shell coated on a surface of the core, and the shell has a dielectric constant higher than that of the core.

The present disclosure provides a thermosetting resin sheet that makes it easier, while an insulating layer where a conductor is to be embedded is being formed, to embed the conductor in the insulating layer and reduces the chances of causing a decline in moldability. A thermosetting resin sheet (1) includes a prepreg layer (2) and a resin sheet layer (3) stacked on the prepreg layer (2). The prepreg layer (2) includes a base member (4) and an uncured product or semi-cured product of a first thermosetting resin composition impregnated into the base member (4). The resin sheet layer (3) is an uncured product or semi-cured product of a second thermosetting resin composition. A curing time of the resin sheet layer (3) is longer than a curing time of the prepreg layer (2).

The disclosure provides a composite for forming an insulating substrate. The composite includes 100 parts by weight of a liquid crystal polymer and 0.5-85 parts by weight of a dielectric additive. The liquid crystal polymer has a repeating unit represented by ##STR00001##
in which Ar is 1,4-phenylene, 1,3-phenylene, 2,6-naphthalene, or 4,4′-biphenylene, Y is —O— or —NH—, and X is carboxamido, imido/imino, amidino, aminocarbonylamino, aminothiocarbonyl, aminocarbonyloxy, aminosulfonyl, aminosulfonyloxy, aminosulfonylamino, carboxyl ester, (carboxyl ester)amino, (alkoxycarbonyl)oxy, alkoxycarbonyl, hydroxyamino, alkoxyamino, cyanato, isocyanato, or a combination thereof.

Provided is a method for producing a wiring circuit board capable of improving the dimensional accuracy of a second conductive layer. The wiring circuit board produced by the producing method includes a metal supporting layer, a first insulating layer disposed on one surface of the metal supporting layer in a thickness direction, a first conductive layer disposed on one surface of the first insulating layer in the thickness direction, a second insulating layer disposed on one surface of the first insulating layer in the thickness direction so as to cover the first conductive layer, and a second conductive layer disposed on one surface of the second insulating layer in the thickness direction. The producing method includes a step of forming the second insulating layer by bonding a film made of a photosensitive resin to one surfaces of the first insulating layer and the first conductive layer in the thickness direction.