A flexible printed wiring board according to an aspect of the present disclosure is a flexible printed wiring board including a base film and a plurality of wiring lines disposed on a front surface of the base film. Each of the wiring lines has a front end surface extending in a longitudinal direction of the wiring line and two side surfaces extending in the longitudinal direction, and the side surfaces have an arithmetical mean roughness Ra of 0.05 .Math.m to 2.0 .Math.m. The wiring lines have an average height of 40 .Math.m to 120 .Math.m. The wiring lines have an average spacing of 1 .Math.m to 30 .Math.m.

Provided is a photosensitive resin composition containing: a photopolymerizable compound (A) having an ethylenically unsaturated group; a photopolymerization initiator (B); and an inorganic filler (F), in which the photopolymerizable compound (A) having an ethylenically unsaturated group includes a photopolymerizable compound (A1) having an acidic substituent and an alicyclic structure together with an ethylenically unsaturated group, and the inorganic filler (F) includes an inorganic filler surface-treated with a coupling agent without at least one functional group selected from the group consisting of an amino group and a (meth)acryloyl group. The present disclosure also provides a photosensitive resin composition for photo via formation, and a photosensitive resin composition for interlayer insulating layer. The present disclosure further provides: a photosensitive resin film and a photosensitive resin film for interlayer insulating layer, each of which contains the photosensitive resin composition; a multilayered printed wiring board and a semiconductor package; and a method for producing a multilayered printed wiring board.

A substrate for a printed wiring board, the substrate includes a base film containing polyimide as a main component and a sinter layer disposed on at least a portion of a surface of the base film and containing copper nanoparticles. The base film contains a nitrogen atom bonded to a copper atom of the copper nanoparticles, an average number of the nitrogen atom bonded to the copper atom per unit area of the surface of the base film on which the sinter layer is disposed is 2.6×10.sup.18 atoms/m.sup.2 to 7.7×10.sup.18 atoms/m.sup.2, and the average number is an average number calculated for a measurement region estimated to have a thickness of 3 nm from a measurement value of the surface of the base film measured by X-ray photoelectron spectroscopy.

This tin or tin alloy electroplating solution according to one aspect contains a soluble salt (A) including at least a stannous salt, one or more compounds (B) selected from the group consisting of an organic acid, an inorganic acid, and a salt thereof, a surfactant (C) that is a polyoxyethylene polycyclic phenyl ether sulfuric acid ester salt represented by the following General Formula (1), and a leveling agent (D).

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In General Formula (1), m is an integer of 1 to 3, n is an integer of 10 to 30, and X is a cation.

Method for electroplating a metal onto a flat substrate P. Surfaces are electrically polarized for metal deposition by feeding thereto at least one first and second forward-reverse pulse current sequences. The first forward-reverse pulse current sequence includes a first forward pulse generating a first cathodic current during a first forward pulse duration t.sub.f1 and having a first forward pulse peak current i.sub.f1, and a first reverse pulse generating a first anodic current during a first reverse pulse duration t.sub.r1 and having a first reverse pulse peak current i.sub.r1, the second forward-reverse pulse current sequence including a second forward pulse generating a second cathodic current during a second forward pulse duration t.sub.f2 and having a second forward pulse peak current i.sub.f2, and a second reverse pulse generating a second anodic current during a second reverse pulse duration t.sub.r2, the second reverse pulse having a second reverse pulse peak current i.sub.r2.

A printed circuit board (PCB) having an engineered thermal path and a method of manufacturing are disclosed herein. In one aspect, the PCB includes complementary cavities formed on opposite sides of the PCB. The complementary cavities are in a thermal communication and/or an electrical communication to form the engineered thermal path and each cavity is filled with a thermally conductive material to provide a thermal pathway for circuits and components of the PCB. The method of manufacturing may further include drilling and/or milling each cavity, panel plating the cavities and filling the cavities with a suitable filling material.

A wiring board includes a wiring layer, an insulating layer, a plurality of opening portions, and a connection terminal. The insulating layer is laminated on the wiring layer and covers a wiring pattern. Each of the plurality of opening portions penetrates through the insulating layer to the wiring pattern. The connection terminal is formed on the respective opening portions and comes into contact with the upper surface of the wiring pattern. The wiring layer includes a first wiring pattern, and a second wiring pattern that is formed of a plurality of laminated metal layers and that is thicker than the first wiring pattern. An upper surface of a metal layer serving as an uppermost layer of the second wiring pattern is a contact surface with the connection terminal and has a same width as an upper surface of a metal layer serving as a layer other than the uppermost layer.

A method for electro-depositing a radioactive material onto a metal substrate is disclosed. This is particularly well-suited for true random number generators. The method includes (a) at least partially masking the metal substrate to expose a metallic surface on the metal substrate; (b) connecting the metal substrate to a cathode of a current source; (c) submersing the exposed metallic surface into a solution containing radioactive metal ions, wherein the solution is connected to an anode of the current source; (d) removing the exposed metallic surface from the solution; (e) removing the solution from the exposed metallic surface; (f) measuring the amount of radioactivity emitted from the exposed metallic surface; and (g) repeating steps (c) through (f) until the amount of radioactivity measured in step (f) stabilizes relative to a previous measurement.

An electromagnetic wave transmission board proofed against internal signal leakage includes an inner plate, a first outer plate, a second outer plate, a first plate bump, a first conductive bump, a second plate bump, and a second conductive bump. The inner plate defines a first through hole with a plated metal layer on the hole wall. The first and second plated bumps are disposed between the first outer and inner plates. The second plate bump and the second conductive bump are disposed between the second outer plate and the inner plate. The plate metal layer, the first plate bump, the first conductive bump, the first outer plate, the second outer plate, the second conductive bump, and the second plated bump jointly form an air-filled chamber. A method for manufacturing the electromagnetic wave transmission board is also provided.

A wiring board includes: a substrate having transparency; a plurality of first wirings which are arranged on an upper surface of the substrate and extend in a first direction and each of which has a back surface in contact with the substrate and a front surface facing an opposite side of the back surface; and has a back surface in contact with the substrate and a front surface facing an opposite side of the back surface. The first wiring has a pair of side surfaces which extend in the first direction and are adjacent to the back surface of the first wiring, and each of the pair of side surfaces of the second wiring is recessed inward. The second wiring has a pair of side surfaces which extend in the second direction and are adjacent to the back surface of the second wiring.