JP3253886B2 - Single-sided circuit board for multilayer printed wiring board, method for manufacturing the same, and multilayer printed wiring board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-sided circuit board for a multilayer printed wiring board, a method for manufacturing the same, and a multilayer printed wiring board, and more particularly, to a connection reliability in which holes for via holes are reliably filled with a conductive material. This is a proposal for a single-sided circuit board with excellent performance.

[0002]

2. Description of the Related Art A conventional multilayer printed wiring board is constituted by a laminate obtained by stacking a copper-clad laminate and a prepreg on each other and integrating them. This laminate has a surface wiring pattern on its surface and an inner layer wiring pattern between the interlayer insulating layers. These wiring patterns are electrically connected to each other between the inner layer wiring patterns or between the inner layer wiring pattern and the surface wiring pattern via through holes formed in the thickness direction of the laminate.

However, in the multilayer printed wiring board having the through-hole structure as described above, since it is necessary to secure an area for forming the through-hole, it is difficult to increase the component mounting density. There is a drawback in that it is not possible to sufficiently cope with the demands for ultra-miniaturization of devices, narrow pitch packages, and practical use of MCMs. Therefore, recently, instead of the multilayer printed wiring board having the through-hole structure as described above, a multilayer printed wiring board having an interstitial via hole (IVH) structure which can easily cope with miniaturization and high density of electronic equipment has been developed. Development is underway.

[0004] The multilayer printed wiring board having the IVH structure is a printed wiring board having a structure in which conductive via holes for connecting conductive layers are provided in each interlayer insulating layer constituting a laminate. That is, this wiring board is electrically connected between the inner wiring patterns or between the inner wiring pattern and the surface wiring pattern by via holes (buried via holes or blind via holes) that do not penetrate the wiring board. Therefore, the multilayer printed wiring board having the IVH structure does not need to particularly provide a region for forming a through hole, and can easily realize miniaturization and high density of an electronic device.

[0005] With respect to such a multilayer printed wiring board having an IVH structure, for example, see page 57 of the ninth circuit packaging academic conference conference proceedings (March 2, 1995), the multi-layer printed wiring board having an all-layer IVH structure is described. Proposals for plate development have been reported. The proposed multilayer printed wiring board uses high-speed micro via hole processing technology using carbon dioxide gas laser, adopts aramid nonwoven fabric and epoxy resin composite material as substrate material, interlayer connection technology by filling conductive paste,
And is manufactured by the following process (see FIG. 1).

First, a material in which an aramid nonwoven fabric is impregnated with an epoxy resin is used as a prepreg, and the prepreg is perforated with a carbon dioxide gas laser, and then the hole thus obtained is filled with a conductive paste. (See FIG. 1 (a)). Next, copper foil is placed on both sides of the prepreg, and heated and pressed by a hot press. This allows
The epoxy resin and the conductive paste of the prepreg are cured and the copper foils on both sides are electrically connected to each other (FIG. 1 (b)
reference). Then, by patterning the copper foil by an etching method, a hard double-sided substrate having via holes can be obtained (see FIG. 1 (c)).

[0007] The double-sided substrate thus obtained is formed into a multilayer as a core layer. Specifically, on both sides of the core layer,
The prepreg filled with the conductive paste and the copper foil are sequentially laminated while being aligned, hot-pressed again, and then the uppermost copper foil is etched to obtain a four-layer substrate (FIG. 1 (d)). , (e)). In the case of further multi-layering, the above steps are repeated to obtain a six-layer or eight-layer substrate.

[0008] The IV according to the prior art as described above
H-structure multilayer printed wiring board is heated by hot press,
The pressing step and the patterning step of the copper foil by etching must be repeated many times, so that the manufacturing process becomes complicated and the manufacturing takes a long time. Moreover, in the multilayer printed wiring board having the IVH structure obtained by such a manufacturing method, it is difficult to confirm the patterning defect of the copper foil in the manufacturing process. When the ning failure occurs, the entire wiring board as a final product becomes defective. In other words, in the above-described conventional manufacturing process, if a defective product is produced even in one of the laminating steps, it must be disposed of another good laminating step, which tends to deteriorate the manufacturing efficiency or the manufacturing yield. There was a fatal drawback.

On the other hand, the inventor has previously proposed a single-sided circuit board for a multilayer printed wiring board which is effectively used for efficiently manufacturing a multilayer printed wiring board having an IVH structure at a high yield. A conductive circuit formed on one side of the substrate and an adhesive layer formed on the other side, and holes are formed in the substrate and the adhesive layer so as to penetrate these layers and contact a conductor. To provide a single-sided circuit board for a multilayer printed wiring board, wherein a via hole filled with a conductive paste is formed by providing
As a multi-layer printed wiring board having an H structure, at least one of circuit boards electrically connected via an IVH includes:
A multilayer printed wiring board composed of the single-sided circuit board has been proposed. Then, a method of manufacturing a multilayer printed wiring board having an IVH structure using the single-sided circuit board is as follows. Forming a conductive circuit by etching a metal foil attached to one surface of an insulating hard substrate; Forming an adhesive layer on a surface opposite to the conductor circuit formed on one surface of the substrate; Forming a hole penetrating the insulating hard substrate and the adhesive layer and contacting a conductor, and filling the hole with a conductive paste to produce a single-sided circuit board; A step of laminating two or more of the single-sided circuit boards or laminating together with another circuit board, and then using the adhesive layer included in the board to integrate them into a multilayer by one press molding; A method for manufacturing a multilayer printed wiring board characterized by passing through is proposed.

The single-sided circuit board according to this proposal does not fill the through hole of the insulating hard substrate with the conductive paste, but fills the hole where one side of the insulating hard substrate is closed with a conductor with the conductive paste. It is such a configuration. For this reason, the above-mentioned proposed method of manufacturing a single-sided circuit board by filling such holes with a conductive paste has a new structural disadvantage that air is easily trapped in the via holes. In particular, in recent circuit boards, about 100,000 holes / m ² per layer
It is necessary to provide many holes, and if even one hole is not filled with the conductive paste, the circuit board itself will have poor connection. Therefore, in order to efficiently manufacture a multilayer printed wiring board having an IVH structure with a high yield, a stable supply of a single-sided circuit board having excellent connection reliability is indispensable. It was necessary to develop a technology that could reliably fill all holes with a conductive material.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art, and a main object of the present invention is to efficiently manufacture a multilayer printed wiring board having an IVH structure at a high yield. An object of the present invention is to provide a single-sided circuit board which is used effectively and has excellent connection reliability. Another object of the present invention is to propose a method for stably manufacturing a single-sided circuit board having excellent connection reliability. Still another object of the present invention is to provide a multilayer printed wiring board having an IVH structure constituted by the single-sided circuit board having excellent connection reliability.

[0012]

Means for Solving the Problems The inventor of the present invention has conducted intensive studies in order to achieve the above-mentioned object, and as a result, has completed the invention having the following features. That is, (1) The present invention is provided on one side of an insulating hard substrate as a single-sided circuit board having excellent connection reliability, which is effectively used to efficiently manufacture a multilayer printed wiring board having an IVH structure with a high yield. In a single-sided circuit board for a multilayer printed wiring board in which a hole closed by a conductive circuit is filled with a conductive substance to form a via hole serving as an interstitial via hole, the via hole covers the inner wall surface and the bottom surface of the hole. The present invention proposes a single-sided circuit board for a multilayer printed wiring board, which is constituted by an electroless plating metal film to be formed and a conductive paste filled in remaining holes. Here, the electroless plating metal is desirably copper.

(2) As a method for stably producing a single-sided circuit board having excellent connection reliability as described in the above (1), the present invention comprises at least the following steps: Forming a conductive circuit by etching a metal foil attached to one surface of an insulating hard substrate; A hole reaching the conductor circuit from the other surface of the insulating hard substrate is formed, and a catalyst nucleus is applied to the inner wall surface and the bottom surface of the hole closed by the conductor circuit to activate the substrate. (C) immersing the substrate in an electroless plating solution to deposit an electroless plating metal film on the inner wall surface and the bottom surface of the hole; A process of filling the entire remaining hole with a conductive paste. Here, the electroless plating metal is desirably copper.

(3) The present invention provides a multilayer printed wiring board having a structure in which laminated materials of a circuit board are electrically connected to each other through interstitial via holes. There is provided a multilayer printed wiring board comprising a single-sided circuit board having excellent connection reliability as described in the above (1).

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A single-sided circuit board for a multilayer printed wiring board according to the present invention has a via hole in which an inner wall surface and a bottom surface of a hole closed by a conductor circuit provided on one surface of an insulating hard substrate are covered. It is characterized in that it is composed of an electroplated metal film and a conductive paste filled in the remaining holes. With such a configuration, the conductor portion in contact with the hole closed by the conductor circuit is not only the bottom surface of the hole but also the other single-sided circuit board through the electroless plated metal deposited on the inner wall surface of the hole. Surface-connected to the conductor part. As a result, when the remaining hole is filled with the conductive paste, even if bubbles are generated at the bottom of the hole, electricity is conducted through the plating film on the wall surface of the hole other than the bottom, for example, so that the conductor of the circuit board is Providing a single-sided circuit board that enables reliable electrical connection between circuits, that is, a single-sided circuit board with excellent connection reliability required for efficiently manufacturing a multilayer printed wiring board having an IVH structure with high yield. can do.

In the single-sided circuit board according to the present invention, examples of the electroless plating metal forming the via hole include copper, nickel, and gold. It is desirable to use

Here, in the single-sided circuit board of the present invention, the via hole plays a role of electrically connecting conductor circuits of each circuit board constituting the multilayer printed wiring board having the IVH structure. In particular, in the present invention, the conductive paste forming the via hole adheres closely to the conductor circuits on the other circuit boards that are stacked adjacently by thermosetting, and electrically connects the respective conductor circuits.

In the single-sided circuit board according to the present invention, the conductor circuit is a surface wiring pattern or an inner layer wiring pattern constituting a multilayer printed wiring board having an IVH structure. Such a conductive circuit is formed by etching a metal foil attached to one surface of an insulating hard substrate, and is preferably a single-sided copper-clad laminate formed by forming a copper foil on one surface of an insulating hard substrate. Is formed by etching the copper foil.

The single-sided circuit board according to the present invention has at least the following steps: Forming a conductive circuit by etching a metal foil attached to one surface of an insulating hard substrate; A hole reaching the conductor circuit from the other surface of the insulating hard substrate is formed, and a catalyst nucleus is applied to the inner wall surface and bottom surface of the hole closed by the conductor circuit to activate the hole. (C) immersing the substrate in an electroless plating solution to deposit an electroless plating metal film on the inner wall surface and the bottom surface of the hole; And filling the remaining holes with a conductive paste.

In the method for manufacturing a single-sided circuit board, it is desirable that the hole which reaches the conductor circuit provided on one side of the insulating hard substrate be formed by laser irradiation. The reason is that the hole for forming the via hole of the single-sided circuit board is advantageous to form a hole with a very small diameter as high as possible, and by applying a laser to the drilling process,
This is because holes having a small diameter can be easily formed at a high density. Also, according to laser drilling,
A hole reaching the conductive circuit from the other surface of the insulating hard substrate, that is, a hole closed by the conductive circuit can be formed without damaging the conductive circuit provided on one surface of the insulating hard substrate. As a result, instead of providing a hole that penetrates the prepreg substrate as in the prior art, a hole having one end closed by a conductive circuit is formed. And the conductor circuit are in surface contact, so that reliable conduction can be obtained. here,
Examples of the laser used in the present invention include a carbon dioxide gas laser, an excimer laser, and a fourth harmonic of a YAG laser. In particular, the carbon dioxide laser is advantageous in that the processing speed is extremely high.

In the above method for manufacturing a single-sided circuit board, the catalyst nucleus may be applied to the inner surface of the hole in the step, for example, by bonding a masking film to the surface of the insulating hard substrate on which the hole is to be formed, This is performed by drilling a hole in the hole and then applying a catalyst nucleus according to a conventional method, and then removing the masking film, so that the catalyst nucleus is provided only on the inner surface of the hole. The activation of the catalyst nucleus can be performed by a known method, for example, by acid treatment. Furthermore, as the electroless plating solution, an electroless metal plating solution having a known component composition can be adopted,
By immersing the substrate in this electroless plating solution, an electroless plating metal is sequentially deposited from the activated catalyst nuclei, and an electroless plating metal film is deposited on the inner surface of the hole with a part of the hole left. You do it.

The single-sided circuit board according to the present invention as described above is individually manufactured in advance as a single-sided circuit board having a conductor circuit on which a predetermined wiring is formed, prior to manufacturing a multilayer printed wiring board having an IVH structure. You. Therefore, it is possible to confirm the presence or absence of a defective portion such as a conductor circuit before laminating these single-sided circuit boards. As a result, if the single-sided circuit board of the present invention is used, only a single-sided circuit board having no defective portion will be used. It can be manufactured with yield.

Further, if the single-sided circuit board of the present invention is used, it is not necessary to repeat the steps of stacking and hot-pressing prepregs as in the prior art. By utilizing the adhesive layer provided on the circuit board, it is possible to perform lamination and integration by a single hot press molding. That is, a multilayer printed wiring board having an IVH structure can be efficiently manufactured in a short time without repeating complicated steps.

The multi-layer printed wiring board having the IVH structure according to the present invention, which is efficiently manufactured at a high yield in this manner, has a multi-layer printed circuit having a structure in which the laminated materials of the circuit board are electrically connected to each other via the IVH. A wiring board,
At least one layer of the circuit board is constituted by the single-sided circuit board of the present invention described above.

Here, the single-sided circuit board constituting the multilayer printed wiring board of the present invention is desirably bonded to another circuit board via an adhesive layer or the like of the single-sided circuit board. As such another circuit board, any of the single-sided circuit board of the present invention and a conventionally known printed wiring board can be used.

The multilayer printed wiring board of the present invention can be formed by various processings generally performed on printed wiring boards, for example, formation of a solder resist on the surface, nickel / gold plating or soldering on the surface wiring pattern. Processing, drilling, cavity processing, through-hole plating and the like can be performed. Further, the multilayer printed wiring board of the present invention is used for mounting electronic components such as IC packages, bare chips, and chip components.

[0027]

FIG. 2 is a longitudinal sectional view of a single-sided circuit board according to an embodiment of the present invention. In this figure, the single-sided circuit board 1
Is composed of an insulating hard substrate 2, a conductive circuit 3 formed by etching a metal foil attached to one surface of the substrate, and an adhesive layer 4 formed on the surface of the substrate opposite to the conductive circuit. The insulating hard substrate 2 and the adhesive layer 4 are provided on a single-sided circuit board in which a hole penetrating these layers and in contact with the conductor circuit 3 is provided, and a via hole 5 filled with a conductive substance is formed in the hole. The via hole 5 is constituted by an electroless plating metal film 6 covering the inner surface of the hole and a conductive paste 7 filling the remaining hole.

FIG. 3 is a longitudinal sectional view of a single-sided circuit board according to another embodiment of the present invention. In this figure, a single-sided circuit board 1 includes an insulating hard substrate 2, a conductor circuit 3 formed by etching a metal foil adhered to one side of the substrate, and a recess formed by the conductor circuit and the substrate. A single-sided circuit board in which an insulating hard substrate 2 is formed with a via hole 5 filled with a conductive substance in a hole penetrating the substrate and making contact with a conductor circuit 3; The via hole 5 is constituted by an electroless plating metal film 6 covering the inner surface of the hole and a conductive paste 7 filling the remaining hole.

Here, it is preferable that the conductor circuit 3 is formed by etching a copper foil of a single-sided copper-clad laminate obtained by forming a copper foil on one side of an insulating hard substrate 2, for example. . Examples of the insulating hard substrate 2 include, for example,
A substrate obtained by curing a glass cloth epoxy resin, a glass nonwoven cloth epoxy resin, a glass cloth bismaleimide triazine resin, an aramid nonwoven cloth epoxy resin, or the like into a plate shape can be used. The adhesive layer 4 can be made of, for example, an epoxy-based, polyimide-based, bismaleimide-triazine-based, acrylate-based, or phenol-based resin adhesive. As the electroless plating metal film 6 constituting the via hole 5, for example, a plating film of copper, nickel, gold or the like can be used. As the conductive paste 7 constituting the via hole 5, for example, a conductive paste of copper, silver, gold, carbon, or the like can be used.

Next, a method of manufacturing the single-sided circuit board according to one embodiment of the present invention shown in FIG. 2 will be specifically described with reference to FIG. (1) First, an insulative hard substrate 12a having a metal foil 13 adhered to one side as shown in FIG. 4A is prepared. It is advantageous to use, for example, a single-sided copper-clad laminate as the insulating hard substrate 12a having the metal foil 13 adhered to one side.

(2) Next, the metal foil 13 is etched,
As shown in FIG. 4B, it is processed into a predetermined pattern shape. Thus, the conductor circuit 13a is formed. As this etching method, known general means can be adopted. When the conductor circuit 13a is used as an inner layer wiring pattern, the surface of the conductor circuit is improved by, for example, applying microetching, roughening plating, or applying double-sided roughened copper foil to improve the adhesion between layers. It is advantageous to roughen the surface by using the means described above.

(3) Next, on the surface of the insulating hard substrate 12a on which the conductor circuit 13a is formed, on the side opposite to the conductor circuit,
As shown in (c), an adhesive layer 14a is formed. The adhesive layer 14a can be formed by applying a predetermined resin adhesive by means of a roll coater, curtain coater, spray coater, screen printing, or the like, or by pre-curing, or by laminating an adhesive sheet. At this time, the thickness of the adhesive layer is advantageously in the range of 10 to 50 μm.

(4) Next, as shown in FIG. 4 (d), a hole 15 which penetrates the adhesive layer 14a and the insulating hard substrate 12a in the thickness direction and contacts the conductor is formed. This hole 15 is preferably formed by irradiating a laser from the side of the adhesive layer 14a of the insulating hard substrate 12a. As the drilling machine for irradiating this laser, for example, a pulse oscillation type carbon dioxide laser machine can be used. By using such a carbon dioxide laser processing machine, 60 to 200 μmφ
Can be formed with high precision. As a result, via holes can be formed at a high density, and a small and high-density multilayer printed wiring board can be manufactured. Note that desmearing can be performed for the purpose of cleaning the conductor circuit surface 18 (the surface in contact with the via hole) at the bottom of the hole 15.

(5) Next, a catalyst nucleus is applied to the inner surface of the hole 15 formed in the above (4) to activate it. Subsequently, the insulating hard substrate 12a is immersed in an electroless plating solution. An electroless plating metal film 16 is deposited on the inner surface of the hole 15.
Here, the application of the catalyst nucleus to the inner surface of the hole 15 is, for example,
A masking film is bonded to the surface of the insulating hard substrate 12a on the side where the holes 15 are drilled, the holes 15 are drilled at predetermined positions, and then a catalyst nucleus is applied according to a conventional method, and then the masking film is removed. By doing this,
Only the inner surface of the hole 15 is provided with the catalyst nucleus. Further, the activation of the catalyst nucleus can be performed by a known method, for example, by performing an acid treatment with dilute sulfuric acid or the like. Further, as the electroless plating solution, an electroless metal plating solution having a known composition such as copper, nickel, and gold can be used.

(5) As shown in FIG. 4 (e), the entire remaining hole is filled with a conductive paste 17 to produce a single-sided circuit board 11a. As a method for filling the conductive paste 17, for example, a screen printing method using a metal mask can be adopted. At the time of filling, it is advantageous to form a protective mask around the hole 15 in order to form the via hole with high precision. The protective mask can be formed by laminating a film or paper on the surface of the adhesive layer 14a and making a hole together during the hole making process. Further, in order to realize a via hole having good connectivity with a conductor circuit serving as an inner layer of another circuit board to be superimposed, it is advantageous to fill the conductive paste 17 to such an extent that the conductive paste 17 slightly projects from the hole 15. is there. The filled conductive paste 17
Is preferably precured in order to enhance the workability of the subsequent steps, and the protective mask is peeled off before lamination.

Next, using the single-sided circuit board according to the embodiment of the present invention shown in FIG. 2, the IVH according to the embodiment of the present invention is used.
One method of manufacturing a multilayer printed wiring board having a structure will be specifically described with reference to FIG. (1) First, a single-sided circuit board 1 (11a) of the present invention, which constitutes a multilayer printed wiring board having an IVH structure, is manufactured according to FIG. (2) In a similar process, the conductor circuits 13b, 13c, 13d are provided on one surface of the insulating hard substrates 12b, 12c, 12d.
And on the other side adhesive layers 14b, 14c, 14d
And the substrate and the adhesive layer are provided with a hole 15 penetrating these layers and contacting a conductor circuit, and the inner surface of the hole 15 is covered with an electroless plating metal film 16 to remain. A single-sided circuit board as shown in FIG. 5, in which a via hole 5 in which the entire hole 15 is filled with a conductive paste 17 is formed.
11b, 11c and 11d are prepared.

(3) Next, the single-sided circuit boards 11a, 11
b, 11c, and 11d are superimposed in a predetermined order while being aligned using guide holes and guide pins provided around the single-sided circuit board. Here, the conductor circuit 13c of the single-sided circuit board 11c is placed above the adhesive layer 14d of the single-sided circuit board 11d.
And a single-sided circuit board on the adhesive layer 14c.
The adhesive layer 14b of 11b is overlapped and the conductive circuit
The adhesive layer 14a of the single-sided circuit board 11a is overlaid on the upper side of 13b.

(4) After the single-sided circuit boards are overlaid in this manner, they are heated and pressed in a temperature range of 140 ° C. to 200 ° C. using a hot press, whereby each single-sided circuit board is press-formed once. Are integrated in a multilayer. It is advantageous to use a vacuum hot press as the hot press. In this step, the single-sided circuit boards 11a, 11b, 11 superimposed via the adhesive layers 14a, 14b, 14c, 14d.
The layers c and 11d are integrated in a multilayer shape by the adhesive layers 14a, 14b, 14c and 14d being closely adhered and thermosetting. At the same time, the conductive paste 17 is also brought into close contact with the corresponding conductor circuit and thermally cured to form a via hole,
A multilayer printed wiring board having an IVH structure is obtained (see FIG. 6).

FIG. 6 is a longitudinal sectional view of a multilayer printed wiring board having an IVH structure according to one embodiment of the present invention. In this figure, a multilayer printed wiring board includes insulating hard substrates 12a and 12a.
b, 12c, 12d, and conductor circuits 13a, 13b, 13c, formed by etching a metal foil attached to one side of the substrate.
13d, and an adhesive layer 14a, 14b, 14c, 14d formed on the surface of the substrate opposite to the conductor circuit. The insulating hard substrates 12a, 12b, 12c, 12d and the adhesive layers 14a, 14b,
14c and 14d include conductor circuits 13a and 13a penetrating these layers.
The inner surface of the hole 15 in contact with 13b, 13c, 13d is covered with an electroless plating metal film 16, and the remaining hole 15 is entirely covered with a conductive paste 17.
The single-sided circuit boards 11a, 11b, 11c, 11d having via holes 5a, 5b, 5d filled with are laminated, and the adhesive layers 14 provided on the single-sided circuit boards 11a, 11b, 11c, 11d respectively.
a, 14b, 14c, 14d are four-layer substrates joined to each other.

Here, the conductor circuit 13a of the single-sided circuit board 11a
The conductor circuit 13d of the single-sided circuit board 11d is formed in a predetermined wiring pattern shape, and is arranged as a surface wiring pattern on the upper surface or the lower surface of the multilayer printed wiring board. The conductor circuit 13b of the single-sided circuit board 11b and the conductor circuit 13c of the single-sided circuit board 11c are respectively formed in a predetermined wiring pattern shape, and are formed below the single-sided circuit board 11a of the multilayer printed wiring board or above the single-sided circuit board 11d. Are arranged as inner wiring patterns.

The via hole 5a is made of an insulating hard substrate.
The via hole 5b is formed penetrating the insulating substrates 12b and 12c and the adhesive layers 14b and 14c in the thickness direction. The via hole 5d is formed so as to penetrate the insulating substrate 12d and the adhesive layer 14d in the thickness direction. The inner surface of each hole is covered with an electroless plating metal film 16, and the entire remaining hole is made of a conductive paste. Filled with 17. Of these via holes, 5a is a blind via hole for electrically connecting between the conductor circuit 13a as the surface wiring pattern and 13b as the inner wiring pattern, and the via hole 5b is a conductor circuit 13b as the inner wiring pattern. A via hole 6d is a blind via hole that electrically connects between the conductor circuit 13c as the inner layer wiring pattern and the conductor circuit 13d as the surface wiring pattern to the electricity 5. And both constitute an interstitial via hole.

The multilayer printed wiring board according to the present invention can mount various electronic components. For example, as shown by a two-dot chain line in FIG. 6, a chip component 8 such as an IC package or a bare chip is mounted on the multilayer printed wiring board. It can be mounted on a predetermined portion of the surface wiring pattern 13a and fixed by the solder 9.

[Other Embodiments] (1) In the above embodiment, a multi-layer printed wiring board in which four-layered single-sided circuit boards are superposed has been described. The present invention can be practiced, and a single-sided printed circuit board, a double-sided printed circuit board, a double-sided through-hole printed circuit board, or a multilayer printed circuit board manufactured by a conventional method is laminated with the single-sided circuit board of the present invention to produce a multilayer printed wiring board. Can be. (2) In the above-described embodiment, the drilling for forming the via hole is performed by means of laser irradiation. However, mechanical means such as drilling and punching may be applied. (3) In the multilayer printed wiring board of the present invention, the surface wiring pattern may be formed only in a pad shape for mounting chip electronic components.

[0044]

As described above, the single-sided circuit board for a multilayer printed wiring board according to the present invention has an electroless plating metal film that covers the inner surface of a via hole and a conductive film that fills the remaining hole portion. With the configuration using the paste, even when the conductive paste entrains air, the electrical connection reliability with other circuit boards is excellent. Therefore, according to the present invention, it is possible to reliably provide a single-sided circuit board excellent in connection reliability required for efficiently manufacturing a multilayer printed wiring board having an IVH structure with a high yield. Further, according to the method for manufacturing a single-sided circuit board according to the present invention, a single-sided circuit board having excellent connection reliability can be stably provided. Furthermore, since the multilayer printed wiring board of the present invention composed of the single-sided circuit board has a structure in which the circuit boards are joined by an adhesive layer or the like,
As a high-density multilayer printed wiring board having an IVH structure, it can be easily provided at a high yield without using a complicated manufacturing method.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one manufacturing process of a multilayer printed wiring board according to a conventional technique.

FIG. 2 is a longitudinal sectional view showing one embodiment of a single-sided circuit board according to the present invention.

FIG. 3 is a longitudinal sectional view showing another embodiment of the single-sided circuit board according to the present invention.

FIG. 4 is a longitudinal sectional view illustrating an example of a manufacturing process of the single-sided circuit board.

FIG. 5 is a longitudinal sectional view showing one manufacturing process of the multilayer printed wiring board according to the present invention.

FIG. 6 is a longitudinal sectional view showing one embodiment of the multilayer printed wiring board according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single-sided circuit board 2 Insulating hard board 3 Conductor circuit 4 Adhesive layer 5, 5a, 5b, 5d Via hole 6 Electroless plating film 7 Conductive paste 8 Chip component 9 Solder 11a, 11b, 11c, 11d Single-sided circuit board 12a , 12b, 12c, 12d Insulating hard substrate 13 Metal foil 13a, 13b, 13c, 13d Conductor circuit 14a, 14b, 14c, 14d Adhesive layer 15 hole 16 Electroless plating film 17 Conductive paste 18 Conductor circuit at bottom of hole surface

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 3/46 H05K 3/40

Claims (5)

(57) [Claims] 1. A conductor circuit provided on one side of an insulating hard substrate.
A single-sided circuit board for a multilayer printed wiring board in which a conductive material is filled in a hole closed by the above to form a via hole to be an interstitial via hole, wherein the via hole covers an inner wall surface and a bottom surface of the hole. A single-sided circuit board for a multilayer printed wiring board, comprising: an electroless plating metal film; and a conductive paste filled in remaining holes. 2. The single-sided circuit board for a multilayer printed wiring board according to claim 1, wherein the electroless plating metal is copper. 3. At least each of the following steps: Forming a conductive circuit by etching a metal foil attached to one surface of an insulating hard substrate; A hole reaching the conductor circuit from the other surface of the insulating hard substrate is formed.
Activated by applying a catalyst nucleus on the wall and bottom, continuing, by immersing the insulating hard substrate in an electroless plating solution, the step of precipitating an electroless plated metal film on the inner wall surface and the bottom of said hole, . 2. The method for manufacturing a single-sided circuit board according to claim 1, further comprising a step of filling the entire remaining hole with a conductive paste. 4. The method for manufacturing a single-sided circuit board according to claim 3, wherein the electroless plating metal is copper. 5. A multilayer printed wiring board having a structure in which laminated materials of a circuit board are electrically connected to each other through interstitial via holes, wherein at least one of the circuit boards has a structure as described in claim 1 or 2. A multilayer printed wiring board comprising the single-sided circuit board according to any one of the preceding claims.