A multilayer board insulating sheet contains a reducing agent.

A method of manufacturing a multilayer substrate includes preparing a plurality of substrates, stacking the substrates with bonding sheets interposed, and a first bonding process of bonding the substrates to each other by partially heating the stacked substrates by a heater and partially melting the bonding sheet. Each of the substrates is provided with a through-hole and a metal film covering an inner peripheral surface of the through-hole. In the first bonding process, the metal film is heated by the heater and heat is transferred from the heater to the bonding sheet via the metal film.

A multi-layer circuit board is formed by positioning a top sub having traces on at least one side to one or more pairs of composite layers, each composite layer comprising an interposer layer and a sub layer. Each sub layer which is adjacent to an interposer layer having an interconnection aperture, the interconnection aperture positioned adjacent to interconnections having a plated through via or pad on each corresponding sub layer. Each interposer aperture is filled with a conductive paste, and the stack of top sub and one or more pairs of composite layers are placed into a lamination press, the enclosure evacuated, and an elevated temperature and laminated pressure is applied until the conductive paste has melted, connecting the adjacent interconnections, and the boards are laminated together into completed laminated multi-layer circuit board.

A method for producing a circuit board includes a first step of arranging a circuit alignment jig having a pierced portion for receiving a circuit conductor corresponding to a circuit pattern on an insulating layer formed on a metal substrate, a second step is inserting the circuit conductor into the pierced portion, and a third step is pressing the circuit conductor to the insulating layer together with the circuit alignment jig.

A pressing area set on a main surface of a plate-shaped holding jig is arranged on contact parts. The contact parts are pressed against a multilayer board while heating the multilayer board and the pressing area of the holding jig is inclined with a warp of the multilayer board. In this way, when pressing for bonding the contact parts is performed, even if the multilayer board is warped by the heating and the contact parts are shifted, the contact parts are pressed against the multilayer board without fail.

A component-embedded substrate includes a laminate and first and second components. The laminate includes resin layers each made of thermoplastic that are laminated together. The first and second components are embedded in the laminate. The first component has a length in the lamination direction that is greater than a length of the first component in a first direction orthogonal or substantially orthogonal to the lamination direction. The first and second components are disposed adjacent to each other in the first direction, and are disposed at respective positions overlapping with each other as viewed from the first direction. A distance between the first and second components in the first direction is less than the length of the first component in the lamination direction.

Provided is a method of manufacturing a circuit board including preparing a board structural body (11) and covering a conductor circuit element (13) on an outermost layer of the board structural body (11) with a cover film (14), wherein a heat treatment is performed while having a release material (15) interposed between the cover film (14) and a heat-processing device. The release material (15) is a laminate at least including, sequentially from the cover film toward the heat-processing device, a low friction film (16) selected from an ultrahigh-molecular-weight polyethylene film and a polytetrafluoroethylene film, a first aluminum foil (17), a first high-density polyethylene film (18a), a second high-density polyethylene film (18b), and a second aluminum foil (19). The first high-density polyethylene film (18a) and the second high-density polyethylene film (18b) are positioned such that respective MD directions are perpendicular to each other.

A flexible printed circuit board according to an aspect of the present invention includes a base film having insulating properties and a conductive pattern laminated to one surface side of the base film. The conductive pattern forms part of a circuit and includes at least one fuse portion having a cross section smaller than the other part. The flexible printed circuit board includes at least one opening passing through front and rear surfaces on at least one of the right and left sides of the fuse portion in a two-dimensional view.

A planarized core material manufacturing method includes: a core material forming step of forming a core material having a first surface and a second surface opposed to the first surface by impregnating glass cloth with a synthetic resin, and drying the glass cloth; and a core material planarizing step of planarizing the first surface or the second surface of the core material by grinding processing or polishing processing. Preferably, a plurality of pieces of the glass cloth are laminated in the core material.

Provided are a maleimide resin composition containing (A) one or more selected from the group consisting of a maleimide compound having two or more N-substituted maleimide groups and a derivative thereof, (B) a modified conjugated diene polymer, and (C) a thermoplastic elastomer other than the above component (B), wherein the component (B) is one resulting from modification of (b1) a conjugated diene polymer having a vinyl group in the side chain with (b2) a maleimide compound having two or more N-substituted maleimide groups; and a prepreg, a resin film, a laminated board, a printed wiring board and a semiconductor package, each using the maleimide resin composition.