JP2000013019A - Built-up multilayer printed wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To maintain a high yield for thinning a film and making small diameter through-holes by installing at least one frame-like conductor layer for warp prevention in an inner layer. SOLUTION: Outer layers 30 stacked on the upper/lower faces of an inner layer 20 and insulting resin layers 3 and patterns 12 formed by patterning copper plating layers, which are sequentially stacked on them, are installed. The inner layer 20 has inner layer conductor layers 2 and dummy patterns 10. The outer layers 30 have outer layer conductor layers 2'. The dummy patterns 10 have frame-like forms along the peripheral edge part of the inner layer 20 and warping of a wiring board 40 is prevented. Since a via hole and the pattern can easily be formed, a high yield can be maintained for thinning a wiring board and making small diameter through hole.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a built-up multilayer printed wiring board and a method of manufacturing the same, and more particularly, to a method for preventing the occurrence of warpage and achieving a high yield for further reducing the thickness of the wiring board and reducing the diameter of through holes. The present invention relates to a built-up multilayer printed wiring board that can contribute to maintenance and a method for manufacturing the same.

[0002]

2. Description of the Related Art At present, demands for printed wiring boards include a reduction in weight and size. Printed wiring boards are becoming more and more fine-patterned, and their thickness tends to become thinner. However, as the thickness of the printed wiring board becomes thinner, the problem of warpage becomes significant. Regarding the warpage of the printed wiring board, JIS C-64
As specified in No. 80, the smaller the thickness of the copper-clad laminate, the lower the standard value, and no specification is made for a thickness of less than 0.8 mm.

In order to solve the above-mentioned problem of warpage, a method has been proposed in which a frame-shaped pattern is left as a so-called dummy pattern 9 on the periphery of the outer layer 30 as shown in FIG.

However, in this method, a step is formed on the base on which the insulating resin layer 3 is provided by the dummy pattern 9, so that the outer conductor layer 2 'and the insulating resin layer 3 are in close contact with each other as shown in FIG. Gap 8 is generated. For this reason, a small diameter (for example, 100 to 150 μmΦ)
Via hole design becomes difficult. Such a gap 8
Even if the insulating resin layer 3 is exposed and developed (FIG. 11) to form a pilot hole 6 serving as a via hole, as shown in FIG.
The “falling out” of the pilot hole 6 becomes worse. Therefore, even if the copper plating layer 7 is formed in such a prepared hole having a poor “penetration”, a highly reliable electrical connection between the layers cannot be secured (FIG. 13).

In the prior art, when the insulating resin layer 3 is formed on a double-sided wiring board on which the dummy pattern is not formed in the inner layer 20, the squirrel film 4 is used.
Even if it is adhered on top, the adhesion is insufficient, and the adhesion between the lith film 4 and the insulating resin layer 3 (particularly, the adhesion at the end of the outer conductor layer 2 ′) is weak. Therefore, the gap 8 is easily generated.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems. It is an object of the present invention to prevent the occurrence of warpage, to further reduce the thickness of the wiring board and to reduce the diameter of through holes. It is an object of the present invention to provide a built-up multilayer printed wiring board capable of contributing to maintaining a high yield of the printed circuit board.

[0007]

SUMMARY OF THE INVENTION The present invention provides a built-up multilayer printed wiring board having an inner layer, outer layers laminated on upper and lower surfaces of the inner layer, and an insulating resin layer and a conductor layer sequentially laminated on the outer layer. Wherein the inner layer has at least one frame-shaped conductor layer for preventing warpage. Thereby, the above object is achieved. In a preferred embodiment, the inner layer has an inner layer resin plate and an inner layer conductor layer laminated on each of the upper and lower surfaces of the inner layer resin plate, and the outer layer is formed on the outer layer resin plate and the outer layer resin plate. And a laminated outer conductor layer.

In a preferred embodiment, the at least one frame-shaped conductor layer is provided along a peripheral portion of the inner layer.

The present invention also relates to a method for manufacturing a built-up multilayer printed wiring board, comprising: an inner layer having at least one frame-shaped conductor layer at a peripheral portion; and outer layers laminated on upper and lower surfaces of the inner layer, respectively. Providing; forming a photosensitive insulating resin layer on the outer layer; exposing and developing the insulating resin layer; forming a copper plating layer on the exposed and developed insulating resin layer; Patterning the copper plating layer.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

FIG. 8 is a sectional view of one embodiment of the built-up multilayer printed wiring board of the present invention. A built-up multilayer printed wiring board 40 shown in FIG. 8 includes an inner layer 20, an outer layer 30 laminated on each of the upper and lower surfaces of the inner layer 20, an insulating resin layer 3 (built-up layer) sequentially laminated on the outer layer, and A pattern 12 (conductor layer) formed by patterning a copper plating layer is provided. Inner layer 2
Reference numeral 0 denotes an inner-layer resin plate 1 and an inner-layer conductor layer 2 and a dummy pattern 10 formed by patterning a copper plating layer laminated on each of the upper and lower surfaces thereof.
It is a double-sided wiring board having a (conductor layer). The outer layer 30 has an outer-layer resin plate 1 ′ and an outer-layer conductor layer 2 ′ formed on the upper surface thereof by patterning a copper plating layer. The dummy pattern 10 has a frame-like shape with a width of about 5 mm along the peripheral edge of the inner layer 20.
0 warpage is prevented.

Next, a method of manufacturing the built-up multilayer printed wiring board 40 of the present invention will be described with reference to FIGS.

(1) First, as shown in FIG.
Is prepared. First, a copper-clad laminate (not shown) having a thickness of 18 μm is provided on each of the upper and lower surfaces of the inner-layer resin plate 1 (the inner layer base material), and then a copper plating layer (not shown) having a thickness of 20 μm is provided. I do. Next, the inner conductor layer 2 and the dummy pattern 10 are formed by a method such as etching. As a result, the distance between the inner resin plate 1 and the inner conductor layer 2 is about 4
A step 11 of 0 μm is formed. The above dummy pattern 1
0 is about 5 mm on the periphery of the inner layer resin plate 1 for preventing warpage.
It is formed in a frame shape with a width of mm. In FIG. 1, through holes are not shown for simplicity, but in an actual wiring board, through holes are formed as necessary.

(2) Next, as shown in FIG. 2, an outer resin plate 1 '(outer base material) and an outer conductor layer 2' are sequentially laminated on the upper and lower surfaces of the inner layer 20, respectively. The outer resin plate 1 ′ and the outer conductor layer 2 ′ form an outer layer 30.
The outer conductor layer 2 'is formed by patterning the copper plating layer by etching or the like in the same manner as in the above step (1). At the time of this patterning, no frame-shaped dummy pattern is provided on the peripheral portion of the outer layer resin plate 1 '.

(3) Next, as shown in FIG.
Is formed on the entire surface of the substrate. The insulating resin layer 3 is typically made of an acrylic resin, a polyimide resin, or the like, and has photosensitivity to light, particularly ultraviolet light. Therefore, the formation of the insulating resin layer 3 is performed under a light beam from which ultraviolet rays are cut. Examples of a method for forming the insulating resin layer 3 include an arbitrary method other than the press lamination method, for example, a printing method, a method of attaching a resin in a film state, and the like.

The insulating resin layer 3 may be formed, for example, as required.
It is thermoset at 150 ° C. for 2 hours.

(4) Next, by photoetching,
A pilot hole 6 serving as a via hole between the insulating resin layer 3 and the outer conductor layer 2 'is formed.

First, as shown in FIG. 4, a squirrel film 4 is attached to the entire surface of the insulating resin layer 3. The squirrel film 4 is attached using a vacuum laminating method while applying pressure under vacuum. In the present embodiment, a positive insulating resin layer 3 is used. That is, since the black portion 13 of the squirrel film 4 shown in FIG. 4 absorbs ultraviolet light in the exposure step described later, the insulating layer immediately below the black portion 13 is not exposed and dissolved in the developing solution in the subsequent developing step. Is done. A negative-type insulating layer using the transparent portion and the black portion of the film in reverse may be used.

Next, as shown in FIG. 5, the surface of the lith film 4 is irradiated with ultraviolet light 5 to expose the insulating resin layer 3. The black portion 13 of the squirrel film 4 absorbs the ultraviolet light 5, while the transparent portion reflects or transmits the ultraviolet light 5.
Therefore, the portion of the insulating layer immediately below the black portion 13 is not exposed, while the portion of the insulating layer immediately below the transparent portion is exposed.
The unexposed portion of the insulating layer is dissolved in a developing solution in a developing step described later, and a portion where electrical connection is desired between layers may be designed according to this principle. That is, the black portions 13 of the squirrel film 4
And a transparent portion of the lith film 4 may be provided in other portions.

Next, the exposed insulating resin layer 3 is developed. The resin constituting the insulating resin layer 3 is classified into an alkali type and a solvent type in development, similarly to a positive type and a negative type in exposure. For the former, use sodium hydroxide aqueous solution.
The latter are certain organic solvents (eg methylene chloride)
It dissolves in water. In this embodiment mode, an insulating resin layer made of a solvent-type resin is used. The exposed insulating resin layer 3 is treated with a developer (such as methylene chloride) to dissolve and remove only the unexposed insulating resin layer. In this way, only the insulating resin layer immediately above the portion where the layers are to be electrically connected is removed.

As described above, the pilot hole 6 of the through hole is formed as shown in FIG.

(5) Next, as shown in FIG. 7, a copper plating layer 7 is formed on the insulating resin layer 3 and on the wall of the prepared hole 6 of the through hole. As a method for forming the copper plating layer 7, any method known in the art can be used. In the present embodiment, chemical copper plating and electroplating are used, and the thickness of the copper plating layer 7 is about 15 to 20 μm. Is controlled so that

(6) Next, as shown in FIG. 8, the copper plating layer 7 formed in the above (5) is patterned by photoetching to form a pattern 12 (conductor layer). The patterning is performed by applying an etching resist such as a photosensitive dry film, exposing, developing, etching,
And an etching resist stripping step. However,
The copper plating layer 7 is not left on the peripheral portion of the wiring board.

In the photo etching of the step (6), the final etching resist stripping step is performed, but in the photo etching of the step (4), the etching resist stripping step is not performed. That is, in the step (4), the insulating resin layer is not removed and becomes a part of the final built-up multilayer printed wiring board.

As described above, the built-up multilayer printed wiring board of the present invention is obtained.

[0026]

According to the present invention, a built-up multilayer printed wiring board which can prevent the occurrence of warpage can be obtained. Since the built-up multilayer printed wiring board of the present invention can easily produce via holes and patterns, it can contribute to maintaining a high yield with respect to further thinning of the wiring board and small diameter through holes. . The built-up multilayer printed wiring board of the present invention
By providing the frame-shaped conductor layer in the inner layer, it is possible to prevent the occurrence of a step when laminating the squirrel film caused by providing the frame-shaped conductor in the outer layer.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one step of a method of manufacturing an embodiment of a built-up multilayer printed wiring board according to the present invention.

FIG. 2 is a cross-sectional view showing one step of a manufacturing method of one embodiment of the built-up multilayer printed wiring board of the present invention.

FIG. 3 is a cross-sectional view showing one step of a manufacturing method of one embodiment of the built-up multilayer printed wiring board of the present invention.

FIG. 4 is a cross-sectional view showing one step of a manufacturing method of an embodiment of the built-up multilayer printed wiring board of the present invention.

FIG. 5 is a cross-sectional view showing one step of a manufacturing method of one embodiment of the built-up multilayer printed wiring board of the present invention.

FIG. 6 is a cross-sectional view showing one step of a manufacturing method of one embodiment of the built-up multilayer printed wiring board of the present invention.

FIG. 7 is a cross-sectional view showing one step of a manufacturing method of an embodiment of the built-up multilayer printed wiring board of the present invention.

FIG. 8 is a sectional view of one embodiment of the built-up multilayer printed wiring board of the present invention.

FIG. 9 is a sectional view of a conventional built-up multilayer printed wiring board.

FIG. 10 is a sectional view showing a defect in a conventional method for manufacturing a built-up multilayer printed wiring board.

FIG. 11 is a cross-sectional view showing a defect in a conventional method for manufacturing a built-up multilayer printed wiring board.

FIG. 12 is a cross-sectional view showing a defect in a conventional method for manufacturing a built-up multilayer printed wiring board.

FIG. 13 is a cross-sectional view showing a defect in a conventional method for manufacturing a built-up multilayer printed wiring board.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 inner layer resin plate 1 ′ outer layer resin plate 2 inner layer conductor layer 2 ′ outer layer conductor layer 3 insulating resin layer 4 lith film 5 ultraviolet light 6 through hole pilot hole 7 copper plating layer 8 gap 9, dummy pattern 11 Step 12 Pattern 13 Black part of lith film 20 Inner layer 30 Outer layer 40 Built-up multilayer printed wiring board

Claims (4)

[Claims] 1. A built-up multilayer printed wiring board comprising an inner layer, outer layers laminated on upper and lower surfaces of the inner layer, and an insulating resin layer and a conductor layer sequentially laminated on the outer layer, wherein the inner layer is warped. A wiring board having at least one frame-shaped conductor layer for prevention. 2. The inner layer has an inner layer resin plate and an inner conductor layer laminated on upper and lower surfaces of the inner layer resin plate, respectively, and the outer layer is laminated on the outer layer resin plate and the outer layer resin. The built-up multilayer printed wiring board according to claim 1, further comprising a conductor layer for an outer layer. 3. The at least one frame-shaped conductor layer,
The built-up multilayer printed wiring board according to claim 1, wherein the built-up multilayer printed wiring board is provided along a peripheral portion of the inner layer. 4. A method of manufacturing a built-up multilayer printed wiring board, comprising: providing an inner layer having at least one frame-shaped conductor layer on a peripheral edge thereof and outer layers laminated on upper and lower surfaces of the inner layer, respectively. Forming a photosensitive insulating resin layer on the outer layer;
Exposing and developing the insulating resin layer; forming a copper plating layer on the exposed and developed insulating resin layer; and patterning the copper plating layer.