Hitachi, Ltd.

Hitachi Metals, Ltd.

Shingo Kumamoto

Haruo Akahoshi

Tokihito Suwa

Hironori Nakanishi

Hideya Yamada

Ichiro Kishigami

A multilayer circuit board including a laminate of at least one insulating layer and at least one wiring layer. The wiring layer is formed by a composite member having a first metal layer and a second metal layer formed on one or both sides of the first metal layer. The first metal layer having a smaller coefficient of thermal expansion than the second metal layer. The second metal layer having a higher electric conductivity than the first metal layer. The insulating layer has a blind via-hole with a bottom provided by a surface of the second metal layer. A layer-to-layer interconnection portion is provided on the surface of the insulating layer and in the blind via-hole and is formed in the blind via-hole to be in contact with the surface of the second metal layer.

Multilayer circuit board, process of manufacturing same, board for multilayer circuitry, and electronic apparatus

A multilayer circuit board having a high level of reliability in terms of electric connection against temperature changes caused by the actual operation of electronic equipment, a manufacturing process, a substrate for multilayer circuitry, and an electronic apparatus. The multilayer circuit board comprises a laminate of at least one insulating layer and at least one wiring layer, wherein the wiring layer is formed by a composite member comprising a first metal layer and a second metal layer formed on one or both sides of the first metal layer, the first metal layer having a smaller coefficient of thermal expansion than the second metal layer, the second metal layer having a higher electric conductivity than the first metal layer, wherein the insulating layer has a blind via-hole with a bottom provided by a surface of the second metal layer, the circuit board further comprising a layer-to-layer interconnection portion on the surface of the insulating layer and in the blind via-hole, wherein the layer-to-layer interconnection portion in the blind via-hole is formed in such a manner as to be in contact with the surface of the second metal layer.

Provided are a heat spreader that can reduce an increase in the thermal expansion coefficient up to high temperatures of not lower than 500.degree. C. and has an excellent thermal expansion property and an adequate heat-conductive property and a method of making the same. This heat spreader comprises high-thermal-conductivity layers made of a Cu-base metal, low-thermal-expansion layers made of an Fe--Ni-base alloy each of which layers is provided with a plurality of through holes, and thermal expansion-restraining layers of a metal with a thermal expansion coefficient .alpha. at 30-800.degree. C. of not more than 7.5.times.10.sup.-6 /.degree. C.

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Yasugi, Japan

Shingo Kumamoto