JPH0818238A - Multi-layer ceramic wiring board and its manufacturing method - Google Patents

Abstract

PURPOSE:To reduce the number of times of copper plating and to form conductor patterns in high precision in a multi-layer printed wiring board used for various electronic equipment. CONSTITUTION:On an insulating substrate formed by a plurality of insulating plates 15a to 15c, in which a conductor pattern for inner layer 12a is formed, with a conductive paste 14 put in through holes 13a to 13c, a through hole 13d having a conductor layer 12d and a conductor pattern for outer layer 12b are formed. This enables the conductor pattern for the inner layer 12a and the conductor pattern for the outer layer 12b to be in the state of continuity by compressing and curing the conductive paste 14 in the through holes 13a to 13c.

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 in various electronic devices such as a video movie camera and a mobile communication telephone, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, with the spread of personal computers, word processors, video movie cameras, mobile phones, and the like, the demand for multilayer printed wiring boards has been increasing. Interstitial via hole (hereinafter referred to as IVH), which is an electrical interlayer connection method using non-penetrating via holes for increasing wiring accommodation and surface mounting density for multilayer printed wiring boards due to reasons such as Formation is beginning to be required.

A conventional method for manufacturing a multilayer printed wiring board will be described below. FIG. 3 shows a conventional method for manufacturing a multilayer printed wiring board having IVH. FIG.
In (c), 1 is a multilayer printed wiring board, 1a and 1b are outer layer printed wiring boards, 2a and 2b are through holes, 2c and 2d are copper plating layers, 3a and 3b.
Is an inner layer conductor pattern, 3c is a copper foil, 4 is a prepreg, 5a and 5b are outer layer conductor patterns, 6a and 6b are IVHs, and 7a is a component hole.

A method of manufacturing the multilayer printed wiring board having the above structure will be described below.

First, a double-sided copper clad laminate in which copper foil 3c is laminated on both sides of a glass cloth base epoxy resin laminate is N
After forming through holes for through holes using a C drilling machine, etc., through holes 2a and 2b for electrically connecting both surfaces and a copper plating layer 2c are formed by copper plating. Through holes 2a and 2b and copper plating The inner layer conductor patterns 3a and 3b are formed on one side of the outer layer printed wiring boards 1a and 1b on which the layer 2c is formed by a method such as etching, and the surface is oxidized as shown in FIG. 3 (a). Outer layer printed wiring board 1a having holes 2a and 2b and inner layer conductor patterns 3a and 3b
And 1b are obtained.

The outer layer printed wiring boards 1a and 1b
A glass cloth impregnated with an epoxy resin or the like is sandwiched between the prepreg 4 and the glass cloth, and the prepreg 4 is placed between the stainless steel plates. Next, after arranging between the hot plates of a heat press (not shown), pressurizing and heating to a predetermined pressure and temperature, the outer layer printed wiring boards 1a and 1b and the prepreg 4 are welded and laminated. As shown in FIG. 3B, a multilayer copper clad laminate having inner layer conductor patterns 3a and 3b on the inner layer is formed.

Next, after forming through holes to be the component holes 7a and mounting holes, etc., copper plating is performed again, and the screen printing method is performed on the surface of the copper plating layer 2d formed on the surfaces of the component holes 7a and the copper plating layer 2c. Or a photo-developing method is used to form an etching resist, and after etching, the etching resist is peeled off to form outer layer conductor patterns 5a and 5b and conductor-formed IVHs 6a, 6 as shown in FIG. 3 (c).
b, the multilayer printed wiring board 1 in which the through holes of the component hole 7a and the mounting hole are formed is obtained.

[0008]

However, in the above-mentioned conventional structure, the through holes 2a and 2b for forming the IVHs 6a and 6b or the component holes 7a and the copper plating layers 2c and 2d for the mounting holes are formed. Multi-layer printed wiring board 1 because it requires plating more than once
Has a problem that the manufacturing process is complicated and the manufacturing cost of the multilayer printed wiring board is increased.

Further, the resin softened and melted from the prepreg 4 during pressurization and heating during molding of the multilayer copper-clad laminate is eluted from the through holes 2a and 2b of the outer layer printed wiring boards 1a and 1b, and after lamination. Since it adheres to the surface of the multi-layered copper clad laminate, there is a problem that it is necessary to remove the adhered resin or take measures to prevent the adhesion of the resin during lamination.

Further, outer layer conductive patterns 5a and 5
b is a copper foil 3c and printed wiring boards for outer layers 1a and 1
copper plating layer 2 for forming through holes 2a and 2b
c and the copper plating layer 2d for forming the through holes of the component hole 7a and the mounting hole have a three-layer structure, so that it is difficult to form the high-density and high-precision outer-layer conductor patterns 5a and 5b. Have

The present invention solves the above-mentioned conventional problems, and reduces the number of times of copper plating for forming IVH and through holes of component holes, and realizes a high-density and highly accurate outer conductor pattern. An object is to provide a printed wiring board and a method for manufacturing the same.

[0012]

To achieve this object, a multilayer printed wiring board according to the present invention has a plurality of insulating plates having through holes filled or coated with a conductive paste and having a conductor pattern for an inner layer formed on the surface thereof. A through hole formed so as to penetrate the front and back surfaces formed by laminating these insulating plates, a conductor layer formed on the surface of the through hole, and an outer layer conductor pattern formed on the front surface or the back surface. I have.

[0013]

With this configuration, the inner layer conductor pattern formed on the plurality of insulating plates and the outer layer conductor pattern formed on the insulating substrate are electrically connected by compression and curing of the conductive paste filled in the through holes of the insulating plate. It can be in a state.

[0014]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a multilayer printed wiring board according to an embodiment of the present invention, and FIG. 2 shows a method for manufacturing a multilayer printed wiring board according to the embodiment of the present invention. 1 and 2, 11 is a multilayer printed wiring board, 12a is a conductor pattern for an inner layer, 12b is a conductor pattern for an outer layer, 12c is a copper foil, 12d is a conductor layer, 13a to 13d are through holes, 14
Is a conductive paste, 15a to 15c are insulating plates, 16 is a printed wiring board for inner layers, and 17 is a film.

The steps of the method for manufacturing the multilayer printed wiring board having the above structure will be described with reference to FIGS. 1 and 2.

First, an insulating plate 1 obtained by impregnating a glass cloth with an epoxy resin and polymerizing the epoxy resin in a semi-cured state 1
FIG. 2 on both sides of the prepreg that constitutes 5a and 15c.
After the film 17 made of polyester resin is vacuum laminated as shown in (a), through holes 13a and 13c having a predetermined diameter are formed by means of NC drilling machine and a drill or a laser beam such as carbon dioxide gas or excimer.

Next, the conductive paste 14 composed of granular copper and epoxy resin is filled in the through holes 13a and 13c formed in the insulating plates 15a and 15c and the film 17 by means of a screen printing method or the like. After filling or applying, the film 17 is peeled and removed as shown in FIG. 2B to form the outer layer insulating plates 15a and 15c.

Next, after vacuum laminating the film on both surfaces of the prepreg which constitutes the insulating plate 15b, a through hole 13b having a predetermined diameter is formed, and the through hole 13b is filled or coated with a conductive paste 14, and then the film is formed. Are removed and removed to form the inner layer insulating plate 15b.

Then, a copper foil 12c having a thickness of 35 μm is laminated on both surfaces of the insulating plate 15b for the inner layer as shown in FIG. 2 (c) by means such as hot pressing, and the laminated copper foil 1 is formed.
After forming an etching resist resist on the surface of 2c by using a screen printing method or a photo developing method, a second chloride
The exposed copper foil on the surface where the etching resist is not formed is removed by etching with a solution of copper or the like, the etching resist is peeled off, and the inner layer conductor 15b is formed on the inner layer insulating plate 15b as shown in FIG. 2D. The inner layer printed wiring board 16 on which the pattern 12a is formed is obtained.

Next, a copper foil 12c having a thickness of 18 μm and an insulating plate 15a for the outer layer, in which the conductive paste 14 is filled or applied in the through holes 13a, a printed wiring board 16 for the inner layer, and an insulating plate 15c for the outer layer are formed. After combining the copper foil 12c having a thickness of 18 μm, the pressure is about 2 to 4 × by a vacuum heat press machine.
The insulating plate 15a for the outer layer and the printed wiring board 1 for the inner layer are heated and pressed under the conditions of 10 ⁴ Pa and a temperature of 150 to 180 ° C.
6 and the insulating layer 15c for the outer layer have a compressibility of 0 due to heating and pressurization.
The layers are laminated so as to be 10% to form a copper clad multilayer insulating substrate as shown in FIG.

Next, after forming a through hole 13d having a predetermined diameter by a means such as an NC drilling machine and a drill at a predetermined position of the laminated copper clad multilayer insulating substrate, the through hole 13d and the copper are removed by electroless or electrolytic copper plating. 12c Conductor layer 12d on the surface
Are formed as shown in FIG.

Next, an etching resist is formed on the surface of the conductor layer 12d of the copper-clad multilayer insulating substrate by using a screen printing method, a photo developing method, or the like, and then the etching resist resist is not formed by a solution of cupric chloride or the like. The exposed conductor layer 12d and the copper foil 12c are removed by etching, the etching resist is peeled off, and the inner layer conductor pattern 12a is formed on the insulating substrate as shown in FIG. 2 (g) and FIG.
And a through hole 13a, 13b and 13c filled or coated with a conductive paste 14 to form a through hole, and a conductor layer 12d in the through hole 13d and an outer layer conductor pattern 12b formed on the surface of the insulating substrate. Get 11.

Comparing the multilayer printed wiring board of the present embodiment thus constructed with the conventional multilayer printed wiring board, I
It is possible to form component holes and outer layer conductor patterns with the same structure as VH with one copper plating treatment, which is less than the conventional two times, and the formation time of the outer layer conductor pattern by etching is reduced to about 2/3. The variation of the finished state of the conductor pattern width for use is 0.05 to 0.03 from the conventional 0.07 mm.
It could be as small as mm.

As described above, according to the present embodiment, it is possible to reduce the number of times of copper plating for forming IVH and through holes by the conventional method, and to form a highly accurate outer layer conductor pattern.

In this embodiment, the through hole is formed in the insulating substrate for the inner layer, the conductive paste is filled or applied, and then the conductor pattern for the inner layer is formed. However, conversely,
After forming a through hole by adhering a film to an insulating substrate for an inner layer on which a conductor pattern for an inner layer is formed in advance, it is possible to fill or apply a conductive paste into the through hole, whichever is convenient for the process. Should be selected.

In this embodiment, the inner layer printed wiring board is formed and then laminated to form the multilayer printed wiring board. Alternatively, copper foil is formed on both surfaces as shown in FIG. 2 (c). Then, only one side is etched to form a pattern, which is used as an outer layer printed wiring board.
A multilayer printed wiring board may be formed in the same manner after stacking using an insulating plate on which the pattern shown in (b) is not formed as an insulating plate for an inner layer.

In the embodiment, the conductive paste 14 is also used.
Is a copper paste composed of granular copper and an epoxy resin, but the conductive paste 14 may contain a metal powder such as gold, silver or tin-lead. Also, copper foil 12
As for c, those having thicknesses of 35 μm and 18 μm were used, but it goes without saying that the thickness of the copper foil 12c is not limited to these.

[0029]

As described above, according to the present invention, the number of times of copper plating can be reduced by selectively filling or coating only the through holes with the conductive paste in advance to obtain interlayer conduction. Since it is possible to prevent the thickness of the outer layer conductor pattern from increasing by repeating the above, it is possible to realize an excellent multilayer printed wiring board that can form a highly accurate outer layer conductor pattern.

[Brief description of drawings]

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

FIG. 2 (a) is a sectional view in a manufacturing process of the same multilayer printed wiring board; (b) is a sectional view in a manufacturing process of the same multilayer printed wiring board; (c) is a sectional view in a manufacturing process of the same multilayer printed wiring board. Sectional view in the manufacturing process of the multilayer printed wiring board (e) Sectional view in the manufacturing step of the same multilayer printed wiring board (f) Sectional view in the manufacturing step of the same multilayer printed wiring board (g) In the manufacturing step of the same multilayer printed wiring board Cross section

FIG. 3A is a cross-sectional view in a manufacturing process of a conventional multilayer printed wiring board, FIG. 3B is a cross-sectional view in a manufacturing process of the same multilayer printed wiring board, and FIG. 3C is a cross-sectional view in a manufacturing process of the same multilayer printed wiring board.

[Explanation of symbols]

 11 Multilayer Printed Wiring Board 12a Inner Layer Conductor Pattern 12b Outer Layer Conductor Pattern 12c Copper Foil 12d Conductor Layers 13a, 13b, 13c, 13d Through Hole 14 Conductive Paste 15a, 15b, 15c Insulation Board 16 Inner Layer Printed Wiring Board 17 Film

Claims (7)

[Claims] 1. A plurality of insulating plates each having a through hole filled or coated with a conductive paste and having a conductor pattern for an inner layer formed on the surface, and a plurality of insulating plates laminated to penetrate the front and back surfaces of the laminated plate. A multilayer printed wiring board having a through hole formed in this manner, a conductor layer formed on the surface of the through hole, and an outer layer conductor pattern formed on the front surface or the back surface of the laminate. 2. The multilayer printed wiring board according to claim 1, wherein a glass cloth base epoxy resin laminated board is used as the insulating board. 3. The multilayer printed wiring board according to claim 1, wherein a glass nonwoven fabric-based epoxy resin laminated board is used as the insulating board. 4. The multilayer printed wiring board according to claim 1, wherein a paper-based epoxy resin laminated board is used as the insulating board. 5. A step of forming a through hole after adhering films to both surfaces of an insulating plate, and a step of filling or applying a conductive paste into the through hole and then peeling off the film to form an insulating plate for an outer layer. A step of adhering copper foil to both surfaces of the outer layer insulating plate and forming an inner layer conductor pattern by etching to form an inner layer printed wiring board; copper foil, the outer layer insulating plate, and the inner layer The printed wiring board, the insulating board for the outer layer, and the copper foil are arranged upward in this order, and the compressibility of the insulating board for the outer layer, the printed wiring board for the inner layer, and the insulating board for the outer layer is 0 to 10%. And a step of forming a copper-clad insulating substrate by stacking so as to form a through hole in the copper-clad insulating substrate, then forming a conductor layer by copper plating on the surface including the through-hole of the copper-clad insulating substrate, Copper foil on the conductor layer and the surface of the copper-clad insulating substrate And a step of forming a conductor pattern for outer layer by etching. 6. A step of forming a through hole after adhering films to both surfaces of an insulating plate, and a step of filling or applying a conductive paste into the through hole and then peeling off the film to form an insulating plate for an outer layer. , A step of forming a through hole after adhering a film to both surfaces of an insulating plate having a conductor pattern for an inner layer formed on the surface, and filling or applying a conductive paste into the through hole, and then peeling off the film for the inner layer A step of forming a printed wiring board, and an insulating plate for the outer layer, a printed wiring board for the inner layer, an insulating plate for the outer layer, and a copper foil in this order upward, in order for the insulating plate for the outer layer and the print for the inner layer. Forming a copper clad insulating substrate by laminating the wiring board and the outer insulating plate so that the compressibility is 0 to 10%; and forming a through hole in the copper clad insulating substrate, and then forming the copper clad insulating board. Surface of the substrate including the through hole Forming a conductor layer by copper plating on
A method for manufacturing a multilayer printed wiring board, comprising: a step of forming a conductor pattern for an outer layer by etching the conductor layer and the copper foil on the surface of the copper-clad insulating substrate. 7. A step of forming a through hole after adhering films to both surfaces of the insulating plate, and a step of filling or applying a conductive paste into the through hole and then peeling off the film to form an insulating plate for an inner layer. A step of adhering copper foil to both surfaces of the inner layer insulating plate and forming a conductor pattern on only one surface by etching to form an outer layer printed wiring board; and an outer layer printed wiring board with the conductor pattern facing upward. , The inner layer insulating plate, and the outer layer printed wiring board with the conductor pattern facing downward in this order upward, and the outer layer printed wiring board, the inner layer insulating plate, and the outer layer printed wiring board compressed. Forming a copper clad insulating substrate by laminating so that the ratio is 0 to 10%, and forming a through hole in the copper clad insulating substrate, and then copper plating the surface including the through hole of the copper clad insulating substrate. By conductor A method for manufacturing a multilayer printed wiring board, comprising the steps of forming a layer, and forming a conductor pattern for an outer layer by etching the conductor layer and the copper foil on the surface of the copper-clad insulating substrate.