JP2003224365A - Single-sided circuit board for multilayer printed wiring board and multilayer printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an effective technique for manufacturing a multilayer printed wiring board with an interstitial via hole structure effectively at high yield. <P>SOLUTION: In single-sided circuit boards (7a, 7b) for a multilayer printed wiring board: conductor circuits (3a, 3b) are provided to one surface of insulating hard substrates (2a, 2b) composed of a single-sided copper clad laminated plate; adhesive layers (4a, 4b) are provided covering the conductor circuit; a hole reaching the conductor circuit is provided to the other surface of the substrate; and via holes (6a, 6b) filled with conductive paste 5 in the hole to project from the substrate are provided. A multilayer printed wiring board 1 of an IVH structure is manufactured effectively at high yield by using the single-sided circuit boards (7a, 7b). <P>COPYRIGHT: (C)2003,JPO

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 and a multilayer printed wiring board manufactured using the single-sided circuit board, and more particularly to a multilayer printed wiring board having an interstitial via hole structure. We propose a single-sided circuit board for a multilayer printed wiring board and a multilayer printed wiring board composed of this single-sided circuit board, which are effective for efficient manufacturing with a high yield.

[0002]

2. Description of the Related Art A conventional multilayer printed wiring board is composed of a copper clad laminate and a prepreg which are laminated and integrated with each other. This laminate has a surface wiring pattern on its surface and an inner 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 through through holes formed in the thickness direction of the laminated body.

However, in the multilayer printed wiring board having the through hole structure as described above, it is difficult to increase the density of component mounting because it is necessary to secure a region for forming the through hole, and thus the portable electronic device is difficult. However, there is a drawback in that it is not possible to sufficiently meet the demands for miniaturization of devices and practical application of narrow pitch packages and MCMs. Therefore, recently, a multilayer printed wiring board having an interstitial via hole (IVH) structure, which is easy to cope with miniaturization and high density of electronic devices, has been replaced with a multilayer printed wiring board having a through hole structure as described above. Development is in progress.

The multilayer printed wiring board having the IVH structure is a printed wiring board having a structure in which conductive via holes connecting the conductor layers are provided in each interlayer insulating layer forming the laminate. That is, in this wiring board, the inner layer wiring patterns are electrically connected to each other, or the inner layer wiring patterns and the surface wiring patterns are electrically connected to each other by via holes (belly via holes or blind via holes) that do not penetrate the wiring substrate. Therefore, in the multilayer printed wiring board having the IVH structure, it is not necessary to specially provide a region for forming the through hole, and it is possible to easily realize miniaturization and high density of the electronic device.

Regarding such a multilayer printed wiring board having an IVH structure, see, for example, Proceedings of the 9th Circuit Assembly Academic Lecture Meeting (March 2, 1995), page 57, a multilayer printed wiring board having an all-layer IVH structure. Proposals for board development have been reported. The proposed multilayer printed wiring board is a high-speed micro via hole machining technology using carbon dioxide gas laser, adopting a composite material of aramid nonwoven fabric and epoxy resin as a substrate material, interlayer connection technology by filling conductive paste,
It was developed based on the following, and is manufactured by the following process (see FIG. 1).

First, a material obtained by impregnating an aramid non-woven fabric with an epoxy resin is used as a prepreg, and this prepreg is subjected to a drilling process by a carbon dioxide gas laser, and then the hole portion thus obtained is filled with a conductive paste. (See Figure 1 (a)). Next, copper foil is placed on both sides of the prepreg and heated and pressed by a hot press. As a result, 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 (see FIG. 1).
(See (b)). Then, the copper foil is patterned by an etching method to obtain a hard double-sided board having via holes (see FIG. 1 (c)).

The double-sided board thus obtained is multilayered as a core layer. Specifically, on both sides of the core layer,
A prepreg filled with the above-mentioned conductive paste and a copper foil are sequentially laminated while aligning them, hot-pressed again, and then the uppermost copper foil is etched to obtain a four-layer board (FIG. 1 (d)). , (e)). When the number of layers is further increased, the above steps are repeated to form a 6-layer or 8-layer substrate.

IV according to the prior art as described above
The H structure multilayer printed wiring board is heated by a hot press,
The pressing step and the copper foil patterning step by etching have to be repeated many times, which complicates the manufacturing process and requires a long time for manufacturing. In addition, the multilayer printed wiring board having the IVH structure obtained by such a manufacturing method is difficult to correct the patterning failure of the copper foil in the manufacturing process, and thus the pattern can be formed in one place (or in one process) in the manufacturing process. When a defective wiring occurs, the entire wiring board, which is the final product, becomes a defective product. That is, in the above conventional manufacturing process, if a defective product is produced even at one place in each laminating process, it is necessary to dispose of other good laminating processes, which is likely to cause deterioration in manufacturing efficiency or manufacturing yield. There was a fatal flaw.

On the other hand, the inventor has previously used an insulating hard substrate as 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 with a high yield. A hole for making a conductor circuit on one surface of this substrate and an adhesive layer on the other surface, and for penetrating these layers and contacting the conductor on the substrate and the adhesive layer. And a via hole filled with a conductive paste is formed to provide a single-sided circuit board for a multilayer printed wiring board.
As a multi-layer printed wiring board having an H structure, at least one of the circuit boards electrically connected through IVH is
A multilayer printed wiring board composed of the above single-sided circuit board was proposed. Then, as a method of manufacturing a multilayer printed wiring board having an IVH structure using the single-sided circuit board, a step of forming a conductor circuit by etching a metal foil attached to one surface of the insulating hard board ,. A step of forming an adhesive layer on the surface opposite to the conductor circuit formed on one surface of the substrate, A step of 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; Stacking two or more of the above single-sided circuit boards or stacking them together with another circuit board, and then using the adhesive layer of the boards to integrate them into a multilayer by a single press molding, A method of manufacturing a multilayer printed wiring board, which is characterized by the above, has been proposed.

In the single-sided circuit board according to this proposal, since it is difficult to position the through hole of the insulating hard substrate and the through hole of the adhesive layer, the insulating hard substrate on the opposite side of the conductor circuit is usually used. After the adhesive layer is formed on the surface, the substrate and the adhesive layer are simultaneously punched to form a hole in contact with the conductor, and the hole is filled with a conductive paste.

However, if the single-sided circuit board is desmeared for the purpose of cleaning the conductor circuit surface in contact with the conductive paste filled in the holes, there is a new problem that the uncured adhesive layer is easily melted. there were.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and its main purpose is to prevent the problems caused by the desmear treatment and to provide a multilayer printed wiring board having an IVH structure. It is an object of the present invention to provide a single-sided circuit board for a multilayer printed wiring board, which is effectively used to efficiently manufacture a printed circuit board with high yield. Another object of the present invention is to provide a multilayer printed wiring board having an IVH structure composed of the above-mentioned single-sided circuit board, that is, by laminating smooth single-sided circuit boards with few irregularities, it is possible to achieve high positional accuracy and flatness. An object of the present invention is to provide a multilayer printed wiring board having an excellent IVH structure.

[0013]

As a result of intensive research aimed at achieving the above-mentioned object, the inventor has completed an invention having the following contents as its gist. That is, (1) as a single-sided circuit board for a multilayer printed wiring board, which is effectively used for efficiently producing a multilayer printed wiring board having an IVH structure with a high yield, the present invention provides an insulating rigid board made of a single-sided copper clad laminate. A conductor circuit is provided on one surface of the substrate and an adhesive layer covering the conductor circuit is provided, and the other surface of the substrate penetrates the substrate and is in contact with the conductor circuit, and one end is closed. Provided is a single-sided circuit board for a multilayer printed wiring board, which has a hole and a via hole formed by filling the hole with a conductive paste so as to project from the surface of the substrate. Here, the conductor circuit is preferably formed by etching a copper foil of a single-sided copper-clad laminate in which a copper foil is attached to one surface of an insulating hard substrate.

(2) As a multilayer printed wiring board having an IVH structure, the present invention provides a multilayer printed wiring board having a structure in which laminated materials of a circuit board are electrically connected through interstitial via holes. At least one of the inner layer circuit boards excluding the board is constituted by the single-sided circuit board described in (1) above, to provide a multilayer printed wiring board.

Using the single-sided circuit board described in (1) above, I
As a method for efficiently manufacturing a multilayer printed wiring board having a VH structure with a high yield, .. a conductor circuit is formed by etching a copper foil attached to one surface of an insulating hard substrate made of a single-sided copper clad laminate Step of doing ,. The other surface of the insulating hard substrate is provided with a hole penetrating the substrate and in contact with the conductor circuit and having one end closed, and a conductive paste is filled in the hole in a state of protruding from the substrate surface. Forming a via hole by. A step of forming a single-sided circuit board by providing an adhesive layer on the conductor circuit forming surface of the insulating hard board, By stacking one or more single-sided circuit boards on the core board or by stacking them together with another circuit board, and then using the adhesive layer provided on the single-sided circuit board, a single press molding can be performed to form a multi-layered structure. We propose a method for manufacturing a multilayer printed wiring board, which comprises the steps of: Here, it is desirable that the hole reaching the conductor circuit from the other surface of the insulating hard substrate is formed by laser irradiation.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The first embodiment of the present invention is for a multilayer printed wiring board which is necessary for efficiently manufacturing a multilayer printed wiring board having an IVH structure with a high yield without causing a defect due to a desmear treatment. It is to provide a single-sided circuit board. That is, a single-sided circuit board for a multilayer printed wiring board according to the present invention, a conductor circuit is provided on one surface of an insulating hard substrate made of a single-sided copper-clad laminate, and an adhesive layer covering the conductor circuit is provided, The other surface of the insulating hard substrate is provided with a hole penetrating the substrate and in contact with the conductor circuit and having one end closed, and the conductive paste is filled in the hole in a state of protruding from the substrate surface. It has a via hole.

In the present invention, the adhesive layer constituting the single-sided circuit board is used to manufacture the IVH-structured multilayer printed wiring board, and
Alternatively, it plays a role of adhesion when it is adhered to another circuit board to be laminated to form a multilayer.

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

In the present invention, the via holes constituting the single-sided circuit board are formed by connecting the conductor circuit of the single-sided circuit board to the multilayer printed wiring board having the IVH structure.
It plays a role of electrically connecting to a conductor circuit on another circuit board to be laminated. That is, a conductive paste filled so as to project from the surface of a board that penetrates the board from one surface of the insulating hard board to reach the conductor circuit is placed on another circuit board that is adjacently laminated. The conductive circuits are in close contact with each other by thermosetting to electrically connect the respective conductive circuits.

In particular, when the single-sided circuit boards are bonded to each other or other circuit boards to be laminated to form a multi-layered structure, the conductors of the single-sided circuit boards are used for the purpose of improving the adhesion strength and connection reliability of each laminated material. The adhesive layer provided on the circuit forming surface is composed of a layer obtained by coating an adhesive on the surface of an insulating hard substrate including a conductor circuit portion, while the conductive paste of the single-sided circuit substrate is connected It is desirable that the holes be filled in a state of protruding from the substrate surface so that the adhesive layer coated on the conductor circuit portion of the circuit substrate can be pierced to make surface contact. The height of the conductive paste protruding from the substrate surface is preferably 0.5 to 5 μm larger than the film thickness of the adhesive layer coated on the conductor circuit portion.

By using the single-sided circuit board having the above-described structure, it is possible to efficiently manufacture a multilayer printed wiring board having an IVH structure with a high yield. less than,
A method for manufacturing a multilayer printed wiring board using the single-sided circuit board according to the present invention will be described. That is, each of the following steps: A step of forming a conductor circuit by etching a copper foil attached to one surface of an insulating hard substrate made of a single-sided copper-clad laminate. The other surface of the insulating hard substrate is provided with a hole penetrating the substrate and in contact with the conductor circuit and having one end closed, and a conductive paste is filled in the hole in a state of protruding from the substrate surface. Forming a via hole by. A step of forming a single-sided circuit board by providing an adhesive layer on the conductor circuit forming surface of the insulating hard board, By stacking one or more single-sided circuit boards on the core board or by stacking them together with another circuit board, and then using the adhesive layer provided on the single-sided circuit board, a single press molding can be performed to form a multi-layered structure. It is characterized by going through the process of integrating into.

The method for manufacturing a multilayer printed wiring board according to the present invention can be applied particularly advantageously when desmearing is performed after forming holes for via holes. This is because, for an insulating hard substrate, an adhesive layer is provided on the surface opposite to the conductor circuit, and a hole that penetrates the substrate and the adhesive layer and is in contact with the conductor circuit is provided to form a conductive paste. In the configuration proposed above in which a via hole is formed by filling, when the resin smear is removed in order to improve the connection reliability of the via hole, the uncured adhesive layer is melted and functions as an adhesive layer. There was a problem that could not be fulfilled. In this respect, according to the above method, the adhesive layer is provided on the same side as the conductor circuit with respect to the substrate, and the via hole is formed before the adhesive layer is formed. This is because it is possible to solve the problem and to stably provide a single-sided circuit board having excellent connection reliability. Even in the configuration in which the adhesive layer is provided on the opposite side of the conductor circuit, the via hole can be formed before the adhesive layer is formed. However, it is not an efficient method and is disadvantageous in that it is difficult to open the adhesive layer according to the via hole.

Further, according to the above-mentioned manufacturing method, since the single-sided circuit boards each having the conductor circuit on which the predetermined wiring pattern is formed are individually manufactured in advance, in addition to the above-mentioned effects, the failure of the conductor circuit or the like on the one-sided circuit board is caused. It is possible to confirm the presence or absence of the part before stacking. As a result, only the single-sided circuit board having no defective portion is used in the stacking stage. Therefore, according to the above manufacturing method, defects are less likely to occur in the manufacturing stage, and the multilayer printed wiring board having the IVH structure can be manufactured with a high yield.

Further, according to the method for manufacturing a multilayer printed wiring board of the present invention, it is not necessary to repeat the steps of stacking prepregs and hot pressing, and one or more single-sided circuit boards are superposed on the core board. By stacking it with another circuit board and using the adhesive layer provided on the one-sided circuit board, it is possible to laminate and integrate them by one hot press molding. Further, the multilayer printed wiring board according to the present invention can be manufactured by the same method as that of the subtractive mass-produced substrate, except for the via hole drilling process. That is, according to the above method, a multilayer printed wiring board having an IVH structure can be efficiently manufactured in a short time without repeating complicated steps.

Here, in the above-mentioned manufacturing method, the conductor circuit is formed by etching the metal foil. The etching of the metal foil allows the extremely thin conductor circuit pattern to have a uniform film thickness and a high density. This is because it can be formed.

In the method for manufacturing a single-sided circuit board according to the present invention, it is preferable that the hole penetrating the insulating hard board and contacting the conductor circuit is formed by laser irradiation.
The reason is that it is advantageous to form the via holes of the single-sided circuit board with holes with a minute diameter as high as possible, and by applying a laser to the drilling process, holes with a minute diameter can be formed. This is because it can be formed easily and with high density. Further, according to the drilling process by the laser, it is possible to make a hole penetrating the insulating hard substrate and contacting the conductor circuit without damaging the conductor circuit. As a result, instead of providing a hole penetrating the prepreg substrate as in the conventional technique, a hole whose one end is closed by a conductor circuit is formed.By filling the hole with a conductive paste, the via hole is formed. Since the conductor circuit makes surface contact with the conductor circuit, reliable conduction can be obtained.

In the method for manufacturing a single-sided circuit board according to the present invention, the desmear treatment is carried out by removing, for example, potassium permanganate liquid, chromic acid and sulfuric acid in order to remove the resin residue remaining on the conductor circuit surface at the bottom of the via hole. This is a treatment of immersing in a mixed liquid or the like. According to the present invention, since the desmear treatment is performed before the formation of the adhesive layer, the problem of the above-mentioned proposal that the uncured adhesive layer is likely to be melted is not caused.

In the present invention, a conventionally known core substrate can be used as the core substrate, and its manufacturing method is not particularly limited. Further, in the present invention, it is not necessary to form an adhesive layer on the outermost circuit board.

The IVH-structured multilayer printed wiring board according to the present invention manufactured as described above is a multilayer printed wiring board having a structure in which the laminated materials of the circuit board are electrically connected to each other through IVH. At least one layer of the inner-layer circuit boards excluding the board is formed of the single-sided circuit board of the present invention.

Here, the single-sided circuit board constituting the multilayer printed wiring board of the present invention is bonded to another circuit board via an adhesive layer. As such other circuit boards,
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 is subjected to various kinds of processing generally performed on printed wiring boards, for example, forming a solder resist on the surface, nickel / gold plating or soldering on the surface wiring pattern. Processing, drilling, cavity processing, through hole plating, etc. 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.

[0032]

FIG. 2 is a vertical sectional view of a multilayer printed wiring board according to an embodiment of the present invention. In this figure, the multilayer printed wiring board 1 includes insulating hard substrates 2a and 2b, conductor circuits 3a and 3b formed by etching a metal foil attached to one surface of the substrates, and the conductor circuit forming surface. Adhesive layer 4 provided
Single-sided circuit boards 7a, 7b, which are composed of a and 4b, and have via holes 6a, 6b filled with a conductive paste 5 in holes penetrating the insulating hard boards 2a, 2b and contacting the conductor circuits 3a, 3b.
Are laminated on both sides of the core substrate 8, and further single-sided circuit boards 7c and 7d not having an adhesive layer formed thereon are respectively laminated on the outermost layers, and the adhesive layer and the single-sided circuit included in the core substrate 8 are laminated. The substrates 7a and 7b are four-layer substrates which are bonded to each other by adhesive layers 4a and 4b, respectively.

Here, the conductor circuit 3a of the one-sided circuit board 7a and the conductor circuit 3b of the one-sided circuit board 7b are respectively formed in a predetermined wiring pattern shape, and are formed on the upper surface or the lower side of the core board 8 in the multilayer printed wiring board 1. It is arranged on the surface as an inner layer wiring pattern. Further, the conductor circuit 3c of the single-sided circuit board 7c and the conductor circuit 3d of the single-sided circuit board 7d are each formed in a predetermined wiring pattern shape and arranged as a surface wiring pattern on the upper surface or the lower surface of the multilayer printed wiring board 1. It Further, the core substrate 8 can be obtained, for example, by forming a through hole in the insulating hard substrate, filling the conductive paste 5, and then forming the conductor circuits 3e on both surfaces.
Incidentally, the conductor circuit 3a, 3b, 3c, 3d, for example, by etching the copper foil of a single-sided copper-clad laminate formed by forming a copper foil on one surface of the insulating hard substrate 2a, 2b, 2c, 2d Those formed are preferred.

Further, the via holes 6a, 6b are formed so as to penetrate the insulating hard substrates 2a, 2b in the thickness direction, and the via holes 6c, 6d form the insulating hard substrates 2b, 2d in the thickness direction. And is filled with the conductive paste 5. Among these via holes, 6a is a belly via hole that electrically connects between the conductor circuits 3a and 3e as the inner layer wiring pattern, and the via hole 6b connects between the conductor circuits 3b and 3e as the inner layer wiring pattern. Berry via hole that electrically connects with via hole 6c
Is a blind via hole that electrically connects between the conductor circuit 3c as the surface wiring pattern and the inner layer wiring pattern 3a, and the via hole 6d is the conductor circuit 3d as the surface wiring pattern and the inner layer wiring pattern 3b. It is a blind via hole that electrically connects between
Both form interstitial via holes.

Insulating hard substrates 2a, 2b, 2c, 2d, 2e
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 layers 4a, 4b and 4e can be made of, for example, an epoxy-based, polyimide-based, bismaleimidetriazine-based, acrylate-based or phenol-based resin adhesive.

As the above-mentioned conductive paste, for example,
A conductive paste such as copper, silver, gold or carbon can be used.

The multilayer printed wiring board of the present invention can be mounted with various electronic parts. For example, as shown by a chain double-dashed line in FIG. 2, a chip part 9 such as an IC package or a bare chip is mounted on the surface wiring pattern 3c. It can be mounted on a predetermined portion of and fixed by the solder 10.

Next, a method of manufacturing the multilayer printed wiring board according to the embodiment of the present invention shown in FIG. 2 will be described. (1) First, the single-sided circuit board 7a (17a) of the present invention which constitutes the multilayer printed wiring board 1 of FIG. 2 is manufactured. This will be specifically described below with reference to FIG. ． An insulating hard substrate 12a having a metal foil 13 as shown in FIG. It is advantageous to use, for example, a single-sided copper clad laminate as the insulating hard substrate 12a having the metal foil 13 attached to one side. ． Next, the metal foil 13 is etched and processed into a predetermined pattern shape as shown in FIG. As a result, the conductor circuit 13a is formed. As the etching method, known general means can be adopted. This conductor circuit 13a is arranged as an inner layer wiring pattern, but in order to improve the adhesion between layers, the surface of the conductor circuit is applied with, for example, micro etching, roughening plating, or double-sided roughened copper foil. It is advantageous to roughen the surface using a known means such as. ． Next, as shown in FIG. 3 (c), the insulating hard substrate 12a
To form a hole 16 that penetrates in the thickness direction of the
Desmearing is performed for the purpose of cleaning the conductor circuit surface 18 at the bottom of the. The hole 16 is preferably formed by irradiating a laser from the side opposite to the conductor forming surface of the insulating hard substrate 12a. As the drilling machine for irradiating the laser, for example, a pulse oscillation type carbon dioxide gas laser processing machine can be used. By using such a carbon dioxide laser processing machine, it is possible to form a hole having a minute diameter of 60 to 200 μmφ with high accuracy. As a result, the via holes can be formed with high density, and a small-sized and high-density multilayer printed wiring board can be manufactured. According to such a drilling method of irradiating a laser, it is possible to drill the portion of the insulating hard substrate 12a without damaging the conductor circuit 13a.
Is open only on the side where the conductor circuit 13a is not formed, and the other end is closed by the conductor circuit. As a result, the via hole and the conductor circuit 13a can be electrically and reliably connected. The desmear treatment is performed, for example, with the purpose of completely connecting the conductor circuit and the conductive paste by completely removing the resin residue remaining on the conductor circuit 18 at the bottom of the hole 16. It is carried out by immersing in a potassium manganate solution, a mixed solution of chromic acid and sulfuric acid, or the like. ． Next, in order to break through the adhesive layer coated on the conductor circuit portion of the other substrate to make surface contact, the holes 16 are electrically conductive while protruding from the substrate surface as shown in FIG. 3 (d). Fill with the conductive paste 5. As a method of filling the conductive paste 5, 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 16 in order to form the via hole with high accuracy. The protective mask can be formed by laminating a film or paper on the insulating hard substrate 12a and punching them together during the punching process. In particular, it is advantageous to fill the conductive paste in a state of protruding from the hole 16 in order to realize a via hole having good connectivity with a conductor circuit which is an inner layer of another circuit board to be overlaid. Further, it is advantageous to pre-cure the filled conductive paste in order to enhance workability in the subsequent steps, and the protective mask is peeled off before stacking. ． Next, as shown in FIG. 3 (e), an adhesive layer 14a is formed on the surface of the insulating hard substrate 12a on which the conductor circuit 13a is formed to produce a single-sided circuit board 17a. The adhesive layer 14a is pre-cured by applying a predetermined resin adhesive by means of a roll coater, curtain coater, spray coater, screen printing or the like. The thickness of the adhesive layer at this time is advantageously in the range of 1 to 15 μm on the conductor circuit.

(2) In the same process, a conductive circuit 13b and an adhesive layer 14b are formed on one surface of the insulating hard substrate 12b, and the insulating hard substrate is penetrated. A single-sided circuit board 17b as shown in FIG. 4 in which a via hole filled with the conductive paste 5 is formed by providing a hole 16 in contact with the conductor is manufactured.

(3) Similarly, insulative hard substrates 12c, 12
For d, a via hole formed by forming conductor circuits 13c and 13d on one surface of this substrate and having a hole 16 penetrating the insulating hard substrate and contacting the conductor and filled with a conductive paste 5 A single-sided circuit board 1 formed as shown in FIG.
7c and 17d are manufactured.

(4) Further, through holes are formed in the insulating hard substrate 12e by laser processing or drilling, the conductive paste 5 is filled, and then the conductor circuits 13e are formed on both surfaces to form the adhesive layer 14e. Then, the core substrate 8 is manufactured.

(5) Next, the single-sided circuit boards 17a, 17 described above
b, 17c, 17d and the core board 8 are superposed in a predetermined order while aligning using guide holes and guide pins provided around the single-sided circuit board and the core board.

(6) After laminating each single-sided circuit board on the core board in this manner, use a heat press to heat the temperature from 140 ° C to 200 ° C.
By heating and pressurizing in the temperature range of ° C, each single-sided circuit board and the core board are integrated into a multilayer by a single press molding. In addition, it is advantageous to use a vacuum hot press as the hot press. In this step, the adhesive layer 14a,
Each single-sided circuit board 17 stacked via 14b and 14e
a, 17b, 17c, 17d and the core substrate 8 are the adhesive layer 14
When a, 14b, and 14e are in close contact with each other and heat-cured, the layers are integrated. At the same time, the conductive paste 5 is also closely adhered to the corresponding conductor circuits and thermally cured,
A via hole is formed and the multilayer printed wiring board 1 is obtained.

[Other Embodiments] (1) In the above embodiments, a multilayer printed wiring board in which a four-layer single-sided circuit board is superposed on a core board has been described. The present invention can be similarly applied to a single-sided printed circuit board, a double-sided printed circuit board, a double-sided through-hole printed circuit board or a multi-layer printed circuit board prepared by a conventional method, and the single-sided circuit board of the present invention is laminated to form a multilayer printed wiring board. It can be manufactured. (2) In the above embodiment, the drilling process for forming the via hole was performed by means of laser irradiation, but mechanical means such as drilling or punching can also be applied. (3) In the multilayer printed wiring board of the present invention, the surface wiring pattern can be formed only in the shape of a pad for mounting a chip electronic component.

[0046]

As described above, according to the single-sided circuit board for a multilayer printed wiring board according to the present invention, it is possible to integrate the layers in a single press molding without causing a problem due to the desmear treatment. It is possible and extremely advantageous in efficiently manufacturing a high-density multilayer printed wiring board having an IVH structure with a high yield. Also, since the multilayer printed wiring board of the present invention has a structure in which the above-mentioned single-sided circuit boards are joined by an adhesive layer, a high-density multilayer printed wiring board having an IVH structure can be obtained by repeating the repeating steps as in the prior art. It can be easily provided without many complicated manufacturing methods.

[Brief description of drawings]

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

FIG. 2 is a vertical cross-sectional view showing an example of the multilayer printed wiring board according to the present invention.

FIG. 3 is a vertical cross-sectional view showing an example of a manufacturing process of a single-sided circuit board used for manufacturing the multilayer printed wiring board.

FIG. 4 is a vertical cross-sectional view showing an example of a step of combining single-sided circuit boards when manufacturing the multilayer printed wiring board.

[Explanation of symbols]

1 Multilayer printed wiring board 2a, 2b, 2c, 2d, 2e Insulating hard substrate 3a, 3b, 3c, 3d, 3e conductor circuit 4a, 4b, 4e adhesive layer 5 Conductive paste 6a, 6b, 6c, 6d, 6e via holes 7a, 7b, 7c, 7d Single-sided circuit board 8 core substrate 9 Chip parts 10 Solder 12a, 12b, 12c, 12d, 12e Insulating hard substrate 13 metal foil 13a, 13b, 13c, 13d, 13e Conductor circuit 14a, 14b, 14e Adhesive layer 16 holes 17a, 17b, 17c, 17d Single sided circuit board Conductor circuit surface at the bottom of 18 holes

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 3/42 610 H05K 3/42 610A F term (reference) 5E317 AA11 AA24 BB02 BB03 BB12 BB13 BB14 CC22 CC25 CD01 CD27 CD32 GG17 5E343 AA15 AA17 AA18 BB23 BB24 BB25 BB58 BB72 DD64 DD76 EE06 EE21 FF02 FF23 GG11 5E346 AA12 AA32 AA43 CC04 CC05 CC09 CC10 CC32 CC38 CC39 DD02 DD13 DD34 EE06 EE08 EE16 GG16 DD02 DD13 DD34 EE06 EE08 EE18 GG16H

Claims (4)

[Claims] 1. A conductive circuit is provided on one surface of an insulating hard substrate made of a single-sided copper-clad laminate, and an adhesive layer covering the conductive circuit is provided, and the other surface of the substrate is provided with:
A hole penetrating the substrate and in contact with the conductor circuit and having one end closed; and a via hole formed by filling the hole with a conductive paste so as to project from the surface of the substrate. Single-sided circuit board for multilayer printed wiring boards. 2. The single-sided circuit board for a multilayer printed wiring board according to claim 1, wherein the conductor circuit is formed by etching a copper foil of a single-sided copper-clad laminate. 3. The multilayer printed wiring board according to claim 1, wherein the hole forming the via hole is formed by laser irradiation, and the resin residue remaining on the bottom of the hole is removed by desmear treatment. Single sided circuit board for. 4. In 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, at least one of inner layer circuit boards excluding a core board is Claim 1
1 to 3, the multilayer printed wiring board comprising the single-sided circuit board according to any one of 1 to 3.