Fujitsu Corporation

Yasutomo Maehara

Kenji Iida

Hideaki Yoshimura

Takashi Nakagawa

Tomoyuki Abe

Shin Hirano

Norikazu Ozaki

Seigo Yamawaki

Takashi Kanda

Kenji Fukuzono

Kaoru Sugimoto

Souichi Obata

Hitoshi Suzuki

Kiyotaka Seyama

Hiroaki Date

Tomohisa Yagi

Kazuhiko Iijima

Seiichi Sugano

A printed circuit board includes a cell portion which includes cells having a plurality of through bores are arranged in a base material; and a base material portion which exists around an outer edge of the cell portion. The base material is formed of a prepreg, the prepreg includes a fiber material in which fiber threads are oriented in a first direction and in a second direction which is perpendicular to the first direction, and a resin material in which the fiber material is impregnated. The through bores are arranged along a third direction between the first direction and the second direction, wherein one side of the outer edges of the cell extends along the third direction.

Printed circuit board incorporating fibers

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

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.

Core substrate and method of producing the same

A process for producing a multilayer board includes the steps of applying a bonding ink to the terminal of the first substrate, the bonding ink including a thermosetting resin containing a filler and a curing agent, the filler being formed of metal particles plated with solder, the metal particles each having a first melting point, and the solder having a second melting point lower than the first melting point; bonding the second substrate to a bonding sheet composed of a thermosetting resin and having a through hole disposed in a portion corresponding to the terminal of the second substrate; and heating and pressurizing the first and second substrates with the bonding sheet in such a manner that the terminals are opposite each other to effect curing of the bonding sheet and the bonding ink and to form an integral structure.

Process for producing multilayer board

It is an object of the present invention to enhance laser beam transmitting efficiency by accurately controlling an interval between a light emitting (light receiving) element () and an optical wave-guide substrate () without causing any fluctuation in the interval in a mounting structure of the light transmitting element in which the light emitting (light receiving) element () is mounted on the optical wave-guide substrate (). When the light emitting (light receiving) element is joined to the sub-mount chip () and when the sub-mount chip () is joined to the optical wave-guide while the element is being directed to the substrate side, the sub-mount chip and the optical wave-guide substrate are joined to each other by the solder bump (). A post () is arranged for regulating an interval between the light emitting (light receiving) element and the optical wave-guide substrate.

Printed board unit for optical transmission and mounting method

A multi-layer wiring board is produced by laminating a plurality of insulating layers having conductor circuits, wherein the conductor circuits of the insulating layers are electrically connected together through via-holes in insulating connection layers having no conductor circuit, and the regions other than the conductor circuits of the insulating layers and the regions other than the via-holes of the connection layers are directly joined together by press-adhering the insulating resins that constitute the respective layers.

Growing community of inventors

Kawasaki, Japan

Yasutomo Maehara