Sumitomo Bakelite Company Limited

Masaaki Kato

Hitoshi Aoki

Kensuke Nakamura

Takeshi Hosomi

Masayoshi Kondo

Toshiaki Chuma

Hideki Hara

Kentaro Fujiura

Satoru Nakao

A multilayer flexible wiring board including (1) plural single-sided wiring boards each having a wiring pattern on one side of the corresponding substrate and two-layer conductor posts projecting from the wiring pattern to the side of the substrate opposite from the wiring pattern, wherein the substrates other than that of the outermost layer have the pads to be connected to the two-layer conductor posts on the side opposite from the conductor posts, and the wiring pattern has no surface coating; (2) a flexible wiring board having on at least one side thereof the pads for connection to the conductor posts and including a wiring pattern with surface coating applied on the flexible portion but no surface coating applied on the multilayer portion, and (3) an adhesive layer having a flux function, wherein the conductor posts and pads are connected by a metal or an alloy, and the wiring patterns are electrically connected.

Circuit board, multi-layer wiring boards, method of producing circuit boards and method of producing multilayer wiring boards

The invention relates to a low-cost transfer bump sheet which is capable of transferring copper-cored solder bumps with high reliability of bonding to a semiconductor chip and which is capable of transferring bumps of various structures. The invention also relates to a low-cost semiconductor flip chip in which copper-cored solder bumps with high reliability of bonding are mounted on a semiconductor chip through the use of the transfer bump sheet. In the transfer bump sheet, metal posts of two or more layers are formed on a base sheet. The invention also relates to a method of manufacturing this semiconductor flip chip, which comprises the steps of forming the base sheet on a metal foil, forming a plating mask on the metal foil, forming a first solder layer (solder coating) on the metal foil by electrolytic plating or electroless plating, removing the plating mask, and forming a metal layer (metal core) of metal posts by the etching of the metal foil through the use of the formed first solder layer (solder coating) as an etching mask.

Transfer bump street, semiconductor flip chip and method of producing same

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Akita, Japan

Masaaki Kato