Fujitsu Corporation

Shin Hirano

Tomoyuki Abe

Kenji Iida

Hideaki Yoshimura

Yasutomo Maehara

Takashi Nakagawa

Norikazu Ozaki

Seigo Yamawaki

Kenji Fukuzono

Takashi Kanda

Kazumasa Saito

The method of producing a substrate comprises the steps of: forming a through-hole in a base member; filling the through-hole with an insulating material; performing electroless plating to coat the surface of the base member, in which the through-hole has been filled with the insulating material, with an electroless-plated layer; applying photo resist on the electroless-plated layer formed on the surface of the base member; optically exposing and developing the photo resist so as to form a resist pattern coating an end face of the through-hole filled with the insulating material; etching an electrically conductive layer formed on the surface of the base member with using the resist pattern as a mask; and removing the resist pattern coating the end face of the through-hole from the base member with using the electroless-plated layer as a release layer.

Method of producing substrate

A wiring substrate includes a core substrate having a first main surface and a mutually opposing second main surface, the second main surface having a conductive property. A first through hole penetrates a core substrate. A first conductive layer extends from the first main surface to the second main surface via the first through hole. An insulating layer is formed on the first conductive layer. A second through hole has the insulating layer as an interior wall. And a second conductive layer is formed inside the second through hole.

Wiring substrate including conductive core substrate, and manufacturing method thereof

The circuit board is capable of tightly bonding a cable layer on a base member even if thermal expansion coefficients of the base member and the cable layer are significantly different. The circuit board comprises: the base member; and the cable layer being laminated on the base member with anchor patterns, which are electrically conductive layers formed on a surface of the base member.

Circuit board and method of producing the same

The method of producing a substrate comprises the steps of: forming a through-hole in a base member; plating the base member so as to coat an inner face of the through-hole with a plated layer; applying photo resist on the base member; optically exposing and developing the photo resist so as to form a resist pattern, which coats at least a planar area of the through-hole; and etching an electrically conductive layer formed on the surface of the base member. The resist pattern is formed so as to separate an area of exposing the conductive layer a prescribed distance away from an edge of the through-hole, and the prescribed length is longer than a distance of etching a side face of the conductive layer in the etching step.

A circuit board has a low thermal expansion coefficient that suits the thermal expansion coefficient of an element to be mounted thereupon and can prevent the occurrence of delamination and cracking of a core layer when the circuit board is used in a low temperature environment. The circuit board is constructed by laminating a core layer and at least one wiring layer, where the at least one wiring layer has slightly smaller external dimensions in a planar direction than the core layer.

Circuit board

The core layer of a core substrate is made of carbon fibers impregnated with resin. When the temperature of the core layer increases, the core layer suffers from an increase in the thickness because of thermal expansion of the resin. The core layer is sandwiched between the insulating layers containing glass fibers. The insulating layers serve to suppress an increase in the thickness of the core layer resulting from the thermal expansion of the core layer. Thermal stress is suppressed in the core substrate.

Core substrate and printed wiring board

Large-sized through holes are formed in a core layer of a printed wiring board. Large-sized vias are formed in the shape of a cylinder along the inward wall surfaces of the large-sized through holes located within a specific area. A filling material fills the inner space of the large-sized via. A small-sized through hole penetrates through the corresponding filling material along the longitudinal axis of the small-sized through hole. A small-sized via is formed in the shape of a cylinder along the inward wall surface of the small-sized through hole. The filling material and the core layer are uniformly distributed within the specific area in the in-plane direction of the core substrate. This results in suppression of uneven distribution of thermal stress in the core layer in the in-plane direction of the core layer.

Printed wiring board

The core substrate is capable of securely preventing short circuit between an electrically conductive core section and a plated through-hole section. The core substrate comprises: an electrically conductive core section having a pilot hole, through which a plated through-hole section is formed; electrically conductive layers coating the inner face of the pilot hole and a surface of the core section; a gas purging hole being formed in the conductive layer coating the surface of the core section; an insulating material filling a space between the inner face of the pilot hole and an outer circumferential face of the plated through-hole section; and cable layers being laminated on both side faces of the core section.

Growing community of inventors

Kawasaki, Japan

Shin Hirano