JPH09232707A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a layer structure of a printed interconnection board from being thick by plating and facilitate forming a fine circuit pattern. SOLUTION: Panel plating of chemical Cu is applied to the entire surface of a laminate 60 having holes 110 for throughholes 10 and holes 21, 31 for IVHs(inner via holes) 20, 30 to form a chemical Cu plated layer 50. Except parts for forming through-hole lands 12, 13 and IVH lands 22, 32, it is masked with a dry film and electrolytically plated to form an electrolytic plated layer 40. The film is removed and etching is applied to form a conductor circuit 51, through-hole lands 12, 13 and IVH lands 22, 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board used for electronic parts and the like.

[0002]

2. Description of the Related Art The IVH method has heretofore been known as a method for manufacturing a printed wiring board capable of forming circuits with high density.
However, the IVH method has a problem that the process is complicated and the cost is high. Further, since the plating layer is formed extremely thick, it is difficult to meet the technical demand for circuit pattern miniaturization that has been recently demanded.

On the other hand, the build-up method has come to be adopted as a means of meeting such technical requirements. The build-up method is a manufacturing method in which an insulating layer and a conductor layer are sequentially laminated, and is excellent in that a via hole can be formed at any position of the conductor layer. However, even in the build-up method, in the process of forming through holes and via holes after forming the laminated body, the laminated body must be subjected to drilling, then plated with chemical copper, and then electrolytically plated. . This is because the chemical copper plating must be applied in advance in order to fix the electrolytic plating.

[0004]

Therefore, since the plating layer has two layers over the entire surface, the layer thickness becomes thicker at the portions other than the land where the through holes and the via holes are formed. It cannot be said to be sufficient to realize the finer pattern.

The present invention solves the above problems, and a printed wiring capable of forming a fine circuit pattern by reducing the thickness of the conductor layer other than the through hole land and the via hole land. A method for manufacturing a board and a printed wiring board manufactured by the method.

[0006]

The printed wiring board according to the present invention is characterized in that the entire surface thereof is subjected to chemical copper panel plating, and further only through holes and via holes are electrolytically plated. .

In the method for manufacturing a printed wiring board according to the present invention, the first step of forming a first hole forming a via hole and the second step of forming a second hole forming a through hole. And a third step of performing panel plating with chemical copper on the entire surface to form a chemical copper plating layer, and attaching a dry film to the entire surface except the portion where the first hole and the second hole are formed. The fourth step,
It is characterized by including a fifth step of electrolytically plating the entire surface, a sixth step of peeling the dry film, and a seventh step of etching the surface to form a circuit.

The dry film used in the method for manufacturing a printed wiring board according to the present invention may be either a positive type or a negative type.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a layered structure of a printed wiring board according to an embodiment of the present invention. The printed wiring board in FIG. 1 has a structure in which a through hole 10, an IVH (inner via hole) 20, and an IVH 30 are formed in a laminated body 60. The laminated body 60 is composed of a conductor layer on which a conductor circuit 61 is formed and an insulating layer 62.

The through hole 10 is composed of a hole 11 penetrating each layer of the laminate 60, through hole lands 12 and 13, an electrolytic plating layer 40, and a chemical copper plating layer 50.

The IVH 20 includes a hole 21, a land 22 and an electrolytic plating layer 4 provided in the outermost insulating layer of the laminate 60.
0, and a chemical copper plating layer 50. Similarly, the IVH 30 is composed of a hole 31, a land 32, an electrolytic plating layer 40, and a chemical copper plating layer 50 provided in the outermost insulating layer of the laminated body 60.

A conductor circuit 51 is formed only on the chemical copper plating layer 50 at predetermined portions other than the through holes 10 and the IVHs 20 and 30.

That is, in FIG. 1, the chemical copper plating is performed by the conductor circuit 51, the through hole 10, the IVH 20 and the I.
Although applied to all VHs 30, electrolytic plating is applied only to through holes 10, IVHs 20 and 30.

Next, the manufacturing process of the printed wiring board according to this embodiment will be described with reference to FIGS. First, as shown in FIG. 2, a laminated body 60 formed by a build-up method.
Holes 22 'and 32' are formed by etching in the outermost layer of. The holes 22 'and 32' are I through the steps described later.
Land 22 and IVH that form VH 20 (FIG. 1)
The land 32 constitutes 30 (FIG. 1).

Then, as shown in FIG. 3, holes 22 'and 3'
The portion corresponding to 2'is irradiated with a laser beam from the outside toward the laminated body, and the holes 21 and 31 are formed in the outermost insulating layer of the laminated body 60.

Further, as shown in FIG. 4, a hole 11 penetrating each layer of the laminated body 60 is formed by an NC drill in a portion corresponding to the through hole.

Next, the entire surface of the laminated body is subjected to panel plating with chemical copper to form a chemical copper plating layer 50 (see FIG. 5), and then, as shown in FIG. The dry film F is adhered to a portion of the IVH 20 other than the land 22 and the IVH 30 other than the land 32 (see FIG. 1).

After that, electrolytic plating is applied to the entire surface of the laminate. As a result, in the state of FIG.
Electrolytic plating layer only on the exposed portion of 0, that is, the portion that becomes the land 12 and the inner wall surface of the hole 11, the portion that becomes the land 22 and the inner wall surface of the hole 21, and the portion that becomes the land 32 and the inner wall surface of the hole 31. 40 is formed. On the other hand, the dry film F is laminated on the upper surface of the chemical copper-plated layer 50 in the other portion (see FIG. 7).
Is deleted (see FIG. 8).

Further, a circuit pattern is formed at a predetermined position as follows. First, a dry film is adhered to expose only the land and the circuit pattern portion, and then the dry film is etched by immersing it in an alkaline solution to remove the dry film in the unexposed portion. Next, the copper foil layer and the chemical copper panel plating layer are melted by etching with ferric chloride. At this time, since the land and the portion corresponding to the circuit pattern are protected by the dry film, the copper foil layer and the chemical copper panel plating layer remain. Finally, the remaining portion of the cured dry film is removed. As a result, FIG.
As shown in, through-hole lands 12, 1 are provided on the copper foil portion.
3, IVH lands 22, 32 and a circuit pattern 51 are formed.

As described above, in the present embodiment, the electrolytic plating is performed only on the portion plated with the chemical copper, and the entire surface of the laminate which has been conventionally used is subjected to the chemical copper plating. Instead of the method of applying
A method is adopted in which after chemical copper plating is applied to the entire surface of the laminate, the portions other than the portions (through holes, IVH) that require electrolytic plating are masked with a dry film and then electrolytic plating is performed. Therefore, through hole, IVH
Since only the chemical copper plating is formed on other portions, the layer thickness does not become thicker than necessary, and the printed wiring board can be miniaturized.

In this embodiment, a negative type film is used as the dry film F, but a positive type film may be used. However, when a positive type film is used, it is formed by reversing the circuit pattern.

[0022]

According to the present invention, the electrolytic plating is applied only to the necessary portions, so that the layer thickness of the printed wiring board can be reduced and the miniaturization can be realized.

[Brief description of drawings]

FIG. 1 is a sectional view of a layer structure of a printed wiring board according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the layer structure at the stage of forming lands in the manufacturing process of the printed wiring board according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of a layer structure at a stage when holes forming a through hole are drilled.

FIG. 4 is a cross-sectional view of the layer structure at a stage where holes forming the IVH are formed.

FIG. 5 is a cross-sectional view of the layer structure at the stage where the entire surface is panel-plated with chemical copper.

FIG. 6 is a cross-sectional view of a layer structure at a stage where a dry film is attached to a portion other than a land.

FIG. 7 is a cross-sectional view of the layer structure at a stage of electrolytic plating.

FIG. 8 is a cross-sectional view of the layer structure at a stage where the dry film is removed.

[Explanation of symbols]

 10 Through Hole 12 Through Hole Land 20, 30 IVH 22, 32 IVH Land 40 Electroplating Layer 50 Chemical Copper Plating Layer 60 Laminate

Claims (5)

[Claims] 1. A printed wiring board, wherein electrolytic plating is applied only to the through holes and the via holes. 2. A laminate comprising a conductor layer having a conductor circuit formed thereon and an insulating layer, a first chemical copper plating layer formed on an inner wall surface of a hole formed in the laminate, and the laminate. A second chemical copper plating layer formed on the surface of the conductor circuit provided on the surface of the outermost layer of the body; and an electrolytic plating layer formed on the surface of the first chemical copper plating layer. The printed wiring board is characterized in that an electrolytic plating layer is not formed on the surface of the chemical copper plating layer. 3. A first step of forming a first hole forming a via hole, a second step of forming a second hole forming a through hole, and a panel plating with chemical copper on the entire surface. A chemical copper plating layer to form a chemical copper plating layer, a fourth step of attaching a dry film to the entire surface except the portions where the first hole and the second hole are formed, and A printed wiring board comprising: a fifth step of electrolytic plating; a sixth step of peeling the dry film; and a seventh step of etching the chemical copper plating layer for forming a circuit. Production method. 4. The method of manufacturing a printed wiring board according to claim 3, wherein a positive type dry film is attached in the fourth step. 5. The method of manufacturing a printed wiring board according to claim 3, wherein a negative dry film is attached in the fourth step.