A circuit board with conductive wiring which is precisely shaped and sized includes a two-part conductive element, namely a first conductive wiring layer and a second conductive wiring layer, a first cover film and a second cover film. The first conductive wiring layer and the second conductive wiring layer are in direct contact to each other. A projection of the first conductive wiring layer and a projection of the second conductive wiring layer along a direction perpendicular to the circuit board overlap with each other. The first and the second cover films wrap the first and the second conductive wiring layers, respectively.

A photosensitive material includes: a compound A having a carboxy group, in which the compound A includes a polymer including a repeating unit derived from (meth)acrylic acid, and a content of the carboxy group in a photosensitive layer which is formed from the photosensitive material is reduced by irradiation with an actinic ray or a radiation.

A method for manufacturing a circuit board includes: preparing a first substrate and a second substrate, wherein: the first substrate comprises a convex post member formed at a top surface of the first substrate, and the second substrate including a first surface and a second surface opposite to the first surface, and comprising: a first metal layer formed on at least the first surface, and an opening through which a top surface of the post member is uncovered in a plan view; bonding at least a portion of a top surface of the first substrate excluding the post member and the second surface of the second substrate so that the top surface of the post member is uncovered through the opening; and forming a circuit pattern by removing a first portion of the first metal layer.

A method for manufacturing a circuit board includes: preparing a first substrate and a second substrate, wherein: the first substrate comprises a convex post member formed at a top surface of the first substrate, and the second substrate including a first surface and a second surface opposite to the first surface, and comprising: a first metal layer formed on at least the first surface, and an opening through which a top surface of the post member is uncovered in a plan view; bonding at least a portion of a top surface of the first substrate excluding the post member and the second surface of the second substrate so that the top surface of the post member is uncovered through the opening; and forming a circuit pattern by removing a first portion of the first metal layer.

An apparatus is used in preparing a printed circuit board (PCB). The apparatus can include a common chassis, an inkjet printer mounted on the common chassis, and a pattern exposer mounted on the common chassis. The inkjet printer can selectively print unexposed photosensitive patterns on a PCB substrate with a photosensitive ink. The pattern exposer can expose said photosensitive patterns to radiation thereby defining exposed patterns. A photosensitive ink for use in an ink jet printer can include a photoresist, a solvent, a humectant, a surfactant, an adhesion promoter, and a basic solution. The adhesion promoter is operative to increase anisotropy of a wet etching process of a copper component on which said photosensitive ink is printed.

To improve a TCT characteristic of a circuit substrate. The circuit substrate comprises a ceramic substrate including a first and second surfaces, and first and second metal plates respectively bonded to the first and second surfaces via first and second bonding layers. A three-point bending strength of the ceramic substrate is 500 MPa or more. At least one of L1/H1 of a first protruding portion of the first bonding layer and L2/H2 of a second protruding portion of the second bonding layer is 0.5 or more and 3.0 or less. At least one of an average value of first Vickers hardnesses of 10 places of the first protruding portion and an average value of second Vickers hardnesses of 10 places of the second protruding portion is 250 or less.

[Problem] To achieve a wiring board capable of suppressing the difference in the amount of delay between two signal wirings constituting differential signal wirings, while securing flexibility in design.

[Solution] A wiring board is configured to include a first insulating layer 1, a first signal wiring 2 and a second signal wiring 3. The first insulating layer 1 includes fibers 4 having the long axis in a first direction and aligned approximately parallel to each other at a first interval and an insulating material 5 filling gaps between the fibers 4 of the first direction. The first signal wiring 2 is formed approximately parallel to the first direction on the first insulating layer 1. The second signal wiring 3 is formed parallel to the first signal wiring 2 such that the interval between the first and second signal wirings 2 and 3 be approximately an integral multiple of the first interval, and the second signal wiring 3 transmits a differential signal of a signal transmitted on the first signal wiring 2.

A substrate for a printed circuit board according to an embodiment of the present invention includes a base film having insulating properties and a sintered layer formed of a plurality of metal particles, the sintered layer being stacked on at least one surface of the base film, in which a region of the sintered layer extending from an interface between the sintered layer and the base film to a position 500 nm or less from the interface has a porosity of 1% or more and 50% or less.

A method of producing a wired circuit board including an insulating layer and a conductive pattern, including: (1), an insulating layer having an inclination face, (2), a metal thin film provided at least on the inclination face, (3), a photoresist provided on the surface of the metal thin film, (4), a light shield portion of a photomask disposed so that a first portion, where the conductive pattern is to be provided in the photoresist, is shielded from light, and the photoresist is exposed to light through the photomask, (5), the first portion of the photoresist is removed to expose the metal thin film corresponding to the first portion, and (6), the conductive pattern is provided on the surface of the metal thin film exposed from the photoresist.

A method of producing a wired circuit board including an insulating layer and a conductive pattern, including: (1), an insulating layer having an inclination face, (2), a metal thin film provided at least on the inclination face, (3), a photoresist provided on the surface of the metal thin film, (4), a light shield portion of a photomask disposed so that a first portion, where the conductive pattern is to be provided in the photoresist, is shielded from light, and the photoresist is exposed to light through the photomask, (5), the first portion of the photoresist is removed to expose the metal thin film corresponding to the first portion, and (6), the conductive pattern is provided on the surface of the metal thin film exposed from the photoresist.