Multilayer printed wiring board and a process of producing same

Abstract

A multilayer printed wiring board which permits the formation of fine wiring patterns, thereby increasing the density of wiring patterns. Using photosensitive glass having a coefficient of thermal expansion close to that of a copper film as a core substrate, a through hole is formed in the photosensitive glass by photolithography, a sputtering silicon oxide layer and a sputtering silicon nitride layer are formed to prevent leak of alkali metal ions from the photosensitive glass, a sputtering chromium layer, a sputtering chromium-copper layer and a sputtering copper layer are formed to enhance the adhesion strength between the copper film and the sputtering silicon oxide layer, and a copper film of 1 to 20 μm thick is formed. With resin filled into the interior of the through hole, a wiring layer is patterned by etching, an insulating layer is formed, and the surface is covered with a surface treatment layer and a cover coat.

Description

BACKGROUND OF THE INVENTION [0001] (1) Field of the Invention [0002] The present invention relates to a multilayer printed wiring board having a multilayer wiring pattern and a process of producing same, and more particularly, to a multilayer printed wiring board which permits the formation of high-density wiring patterns and a production process therefor. [0003] (2) Description of the Related Art [0004] In recent years, MCM (Multi Chip Module) having a plurality of bare-chip LSIs mounted at high density on a multilayer wiring board has come to be widely used. MCM is used in various types of OA equipment, mobile communication equipment, industrial equipment, etc., such as in notebook computers and mobile phones, and has been greatly contributing to the reduction in size and weight of such equipment. In the field of notebook computers, mobile phones and the like, further reduction of their size and weight is expected in future as well, and thus there will inevitably be a demand for c...

AI Technical Summary

Benefits of technology

[0011] The present invention was created in view of the above circumstances, and an object thereof is to provide a multilayer printed wiring board which permits the formation of fine wiring patterns, thereby increasing the density of wiring patterns.

Problems solved by technology

In the case of the ceramic wiring board, however, since the wiring pattern is printed on a green sheet, it is difficult to form a high-density wiring pattern.

Further, in the ceramic wiring board, a through hole is formed by punching, and thus it is difficult to form a small-diameter through hole.

As a result, the land has an increased width corresponding to the diameter of the through hole, also making it difficult to enhance the density of the wiring pattern.

When such a thick copper film is etched, the amount of side etching tends to increase, giving rise to a problem that the wiring of the core layer cannot be made fine.

Further, in the buildup wiring board, a through hole is formed by drilling, and thus it is difficult to form a through hole with a diameter of 0.3 mm or less.

As a result, the land has an increased width corresponding to the diameter of the through hole, also making it difficult to enhance the density of the wiring pattern.

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