Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1998-12-22
2002-04-30
Arbes, Carl J. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S846000, C029S852000, C174S261000, C174S262000
Reexamination Certificate
active
06378199
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a multi-layer printed-wiring board and a process for producing it, and transferring original plates used in producing the multi-layer printed-wiring board and a process for producing them, and particularly to a multi-layer printed-wiring board having a highly precise pattern, a process for producing such a multi-layer printed-wiring board at low cost, and transferring original plates with which the above multi-layer printed-wiring board can be advantageously produced from the industrial viewpoint, and a process for producing them.
BACKGROUND ART
Remarkable development of the semiconductor technology has made rapid progress in miniaturizing semiconductor packages, using a configuration of as many pins as possible, realizing fine pitches, and minimizing the dimensions of electronic parts, thereby rushing into a so-called high-density packaging era. With the progress, the printed-wiring boards are also changing from single-side wiring to double-side wiring, and further to multi-layer wiring and thin-film structure.
Presently, the subtractive process and the additive process are mainly used to form copper patterns on the printed-wiring boards.
The subtractive process is a process consisting of forming holes in a copper-clad laminate, thereafter depositing a copper plating layer inside the holes and on the surface of the laminate, and then performing photo-etching to form patterns. This subtractive process is technically highly completed and low in cost, but it is difficult to form fine patterns because of restriction resulting from the thickness of a copper foil, for example.
On the other hand, the additive process is such a process that a resist layer is formed on portions except for circuit-pattern-forming portions on a laminate containing a catalyst for electroless plating and that circuit patterns are formed on the exposed portions on the laminate by electroless copper plating or the like. The additive process does permit fine patterns to be formed, but has drawbacks in terms of cost and reliability.
Used for forming multi-layer boards is a method for laminating under pressure a single-sided or double-sided printed-wiring board produced by either of the above methods etc. together with a pre-preg in a semi-curing condition, in which an epoxy resin etc. is impregnated in glass cloth. In this case, the pre-preg roles as an adhesive for layers, and connection between the layers is made by forming through holes and effecting electroless plating inside thereof.
Further, the progress of the high-density packaging demands to decrease the thickness and weight of multi-layer boards and also to raise wiring capacity per unit area, which results in producing ideas on the decrease of the thickness of board per layer, the method for connection between layers, the method for mounting parts, etc.
However, the production of multi-layer board using the double-side printed-wiring board produced by the above subtractive process had a limit of increasing the density in terms of the precision of drilling for forming holes in the double-side printed-wiring board and the limit of scale down, and was difficult to decrease the manufacturing cost in addition.
On the other hand, there is a recently developed multi-layer wiring board that is produced by laminating electrically conductive pattern layers and electrically insulating layers successively on a substrate, which meets the above-described demand. Since this multi-layer wiring board is produced by alternately performing photo-etching of a copper plating layer and patterning of a photosensitive resin, this process permits highly precise wiring and connection between layers at arbitrary position.
However, because in this method the copper plating and photo-etching were performed alternately plural times, the procedures were complicated; and because this method was a series process in which the layers were laminated one by one on the substrate, it was difficult to recover a product once trouble occurred in an intermediate step, which was a hinderance to the decrease in the production cost.
Furthermore, because in the conventional multi-layer wiring boards, connection between layers was effected by forming via holes, complicated photolithography steps were required, which was another obstacle against the decrease in the production cost.
DISCLOSURE OF THE INVENTION
The present invention has been accomplished taking the above points into account, and an object of the present invention is to provide a multi-layer printed-wiring board having a highly precise pattern, a process in which such a multi-layer printed-wiring board can be produced by a transfer-lamination-on-substrate method without including the photolithography step, transferring original plates with which the above multi-layer printed-wiring board can be advantageously produced from the industrial viewpoint, and a process for producing them.
A first feature of the present invention is a multi-layer printed-wiring board comprising a substrate for multi-layer printed-wiring board and a plurality of wiring pattern layers having sequentially been transferred onto the substrate, wherein each wiring pattern layer has an electrically conductive layer and an electrically insulating resin layer formed below the electrically conductive layer, and said insulating resin layer is fixed to the substrate or to a lower wiring pattern layer.
A second feature of the present invention is a multi-layer printed-wiring board comprising a substrate for multi-layer printed-wiring board and a plurality of wiring pattern layers having sequentially been transferred onto the substrate, wherein each wiring pattern layer has an electrically conductive layer and an electrically insulating resin layer formed below the electrically conductive layer; said insulating resin layer is fixed to said substrate or a lower wiring pattern layer; and an additional electrically insulating layer is interposed in an overlapping portion between the wiring pattern layers.
A third feature of the present invention is a multi-layer printed-wiring board comprising a substrate for multi-layer printed-wiring board and a plurality of wiring pattern layers having sequentially been transferred onto the substrate, wherein each wiring pattern layer has an electrically conductive layer and an adhesive layer formed below the electrically conductive layer, and an insulating resin layer is formed between upper and lower wiring pattern layers in a portion where the wiring pattern layers intersect or overlap in multi-layer structure with each other.
A fourth feature of the present invention is a multi-layer printed-wiring board comprising a substrate for multi-layer printed-wiring board and a plurality of wiring pattern layers having sequentially been transferred onto the substrate, wherein each wiring pattern layer has an electrically conductive layer, and an electrically insulating resin layer is formed between upper and lower wiring pattern layers in a portion where the wiring pattern layers intersect or overlap in multi-layer structure with each other.
A fifth feature of the present invention is a printed-wiring board comprising a substrate for printed-wiring board and a wiring pattern layer formed on the substrate, wherein a part of said wiring pattern layer is constituted by arranging a plurality of lines each having a small linewidth in parallel.
A sixth feature of the present invention is a process for producing a multi-layer printed-wiring board, comprising:
a step of forming on electrically conductive substrates respective wiring pattern layers, each having an electrically conductive layer and a sticky or adhesive, electrically insulating resin layer laid on said conductive layer, thereby preparing a plurality of transferring original plates; and
a step of pressing said transferring original plate onto a one-side surface of the substrate for multi-layer printed-wiring board and releasing said electrically conductive substrate, thereby transferring said wiring pattern layer to said substrate;
wherei
Kawai Kenzaburo
Kobayashi Shin-ichi
Yoshinuma Hiroto
Arbes Carl J.
Dai Nippon Printing Co. Ltd.
Parkhurst & Wendel L.L.P.
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