JPH09181452A - Multilayer printed wiring board manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the connection reliability and productivity by ensuring an electric conduction between upper and lower layers. SOLUTION: A multilayer printed wiring board manufacturing method comprises previously forming protrudent conductive parts 4 at positions to ensure electric conduction between layers on the surface of an inner layer sheet 3 having a wiring pattern 2 and laminating and forming metal foils 6 through insulating layers so that the conductive parts 4 pierce the insulation layers to ensure the interlayer electric conduction wherein the metal foil 6 is coated with a thermosetting resin at the B-stage state at which the resin is molten at a high temp., to form an insulation film, thereby forming a resin-coated metal foil 5 which is then formed on the sheet 3 having the conductive parts 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a multilayer printed wiring board, and more particularly, to a method of forming a conductive path for making an interlayer connection of a multilayer printed wiring board.

[0002]

2. Description of the Related Art In a conventional method of manufacturing a multilayer printed wiring board, a method is generally used in which a through hole is formed by drilling, and the through hole is plated to form a conductive path for electrical connection between layers. there were. However, in order to achieve higher densities, non-through via holes called via holes are formed between the layers instead of through holes, and a conductive substance is applied to the via holes to form conductive paths for electrical connection between the layers. The forming method has been widely used in recent years.

As one of the processing methods for forming the non-penetrating via hole, a metal foil at a position where the via hole is to be formed is removed, and then the via hole is formed in the thermosetting resin layer by CO ₂ laser processing. There is a method called a conformal mask laser method.

As a method of making a hole by the laser processing, for example, as disclosed in Japanese Patent Application Laid-Open No. 58-64097, a thermosetting resin layer is formed on the surface of an inner layer substrate on which a wiring pattern is formed. There is a method in which a metal foil is adhered to the via hole, the metal foil at a position where the via hole is to be formed is removed, and the via hole is formed in the exposed thermosetting resin layer by laser processing.

In this technique, only the thermosetting resin is removed by a laser by utilizing the high reflectance of a metal layer embedded in an inner layer of a laser beam, and a non-penetrating via hole is formed. According to this method, the holes are drilled one by one by a laser, and the production cost and the processing time are enormous.

A conductive path for electrically connecting the upper and lower layers can be formed by panel plating of the via hole formed by the laser. At this time, plating is deposited not only on the via holes but also on the surface metal foil, which increases the thickness of the surface metal foil and hinders formation of a fine circuit in the metal foil.

In addition, the processing method for forming the non-penetrating via hole is rationalized, and panel plating for establishing electrical connection of the via hole at the same time as the formation of the via hole is omitted. as a method of avoiding an increase in the surface copper thickness by plating deposition on foils, e.g., 9th circuit mounting academic Lecture convention as introduced in "new method (B ² it) proposed by the printed wiring board" On the surface of the inner layer substrate corresponding to the position where the via hole is to be formed, a convex conductive bump is formed in advance and laminated with a metal foil via a glass epoxy prepreg impregnated with epoxy resin on a glass base material However, there is a method in which a conductive bump penetrates through the glass epoxy prepreg to form a conductive path instead of a via hole and to electrically connect the upper and lower layers.

However, the method of manufacturing a multilayer printed wiring board using conductive bumps has a small number of steps and is easy to reduce the cost. However, when the conductive bumps penetrate the glass epoxy prepreg to form a conductive path, the glass epoxy prepreg does not have to be used. The variation in the density of the glass fibers that constitutes the above-mentioned structure causes variations in the penetration of the conductive bumps, and the reliability of the electrical connection between the upper and lower layers becomes poor. In addition, the portions that require electrical connection between the upper and lower layers will break the glass fibers of the glass epoxy prepreg, and when heating and pressing for multilayer molding, the prepreg will be broken and defects such as voids and blisters will occur. May occur.

In the method using the conductive bumps,
For example, the thickness of the base material constituting the prepreg is 200 μm
When the thickness is of the order of magnitude, the height of the conductive bump penetrating this prepreg becomes 200 μm or more, and the bottom surface area of the conductive bump formed in this way also becomes large, impeding the formation of a fine circuit.

As described above, the method using conductive bumps has a small number of steps and is easy to reduce the cost, but has a problem that the reliability of various connections is lowered in terms of both product reliability and manufacturability. There is a demand for a method capable of forming via holes that can improve the properties.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and ensures electrical conduction between upper and lower layers, has high connection reliability, and has high productivity. It is an object of the present invention to provide a method of manufacturing a multilayer printed wiring board which is improved.

[0012]

According to a first aspect of the present invention, there is provided a method for manufacturing a multilayer printed wiring board, wherein a surface of an inner layer substrate having a wiring pattern is preliminarily projected at a position where electrical conduction between layers is intended. Of a multi-layer printed wiring board in which a conductive portion having a circular shape is formed, a metal foil is laminated and formed through an insulating layer, and the conductive portion having a convex shape penetrates the insulating layer to electrically connect the layers. In the method, a thermosetting resin in a B-stage state that melts at a high temperature is applied to the metal foil to form a resin-coated metal foil having an insulating layer formed thereon, and the inner layer substrate having the convex conductive portion formed therein. And the resin-coated metal foil are laminated and formed.

In the method for manufacturing a multilayer printed wiring board according to a second aspect of the present invention, convex conductive portions are previously formed on the surface of the inner layer substrate on which the wiring patterns are formed, at positions where electrical conduction between the layers is intended. Formed and laminated metal foil through the insulating layer,
In the method for manufacturing a multilayer printed wiring board, wherein the convex conductive portion penetrates an insulating layer to achieve electrical conduction between layers,
A first resin layer that softens at a high temperature and a second resin layer that melts at a low temperature are applied to the metal foil to form a resin-coated metal foil having an insulating layer, and the convex conductive portion is formed. The inner layer substrate and the resin-coated metal foil are laminated and formed.

A method for manufacturing a multilayer printed wiring board according to a third aspect of the present invention is characterized in that the convex conductive portion is formed by using a metal paste and / or a metal molded body.

A method of manufacturing a multilayer printed wiring board according to a fourth aspect of the present invention is characterized in that the metal paste and / or the metal molded body is formed of a simple substance of gold, silver or copper or an alloy thereof. To do.

A method for manufacturing a multilayer printed wiring board according to a fifth aspect of the present invention is characterized in that the convex conductive portion is formed by using solder.

A method for manufacturing a multilayer printed wiring board according to a sixth aspect of the present invention is characterized in that the top of the convex conductive portion is plated with gold.

According to a seventh aspect of the present invention, in the method for manufacturing a multilayer printed wiring board, the resin-coated metal foil is formed by gold-plating a surface on which the resin is applied, and then applying the resin thereon. Is characterized by.

The method for producing a multilayer printed wiring board according to claim 8 of the present invention is characterized in that the resin layer forming the resin-coated metal foil is formed of a resin composition having anisotropic conductivity. To do.

In the method for producing a multilayer printed wiring board according to claim 9 of the present invention, the first resin layer constituting the resin-coated metal foil according to claim 2 is a resin composition having anisotropic conductivity. It is characterized by being configured.

In the method for producing a multilayer printed wiring board according to a tenth aspect of the present invention, the resin composition having anisotropic conductivity has conductivity such as graphite, whiskers, carbon, and conductive metal particles. It is a resin composition containing any of the particles.

Hereinafter, the present invention will be described in detail.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The inner layer substrate having a wiring pattern used in the present invention includes, for example, one having a circuit formed on a glass epoxy copper clad laminate, and the wiring pattern has a roughened surface. It is preferable that a surface treatment such as a treatment is applied in order to improve the adhesiveness.

As a method of forming a convex conductive portion at a position requiring electrical connection with the upper layer of the wiring pattern, for example, a printing method, a dipping method, a gang bonding method, and a vibration transfer device are used. And the like. The convex conductive portion may have a pointed top, a spherical shape, a flat shape, or the like. The convex conductive portion is preferably composed of a metal paste, a metal molded body or an alloy thereof, and gold, silver, copper, solder or the like is preferably used as the conductive material.

Further, it is preferable that the top of the convex conductive portion is plated with gold. By plating with gold, the top of the conductive portion comes into contact with the metal foil when laminated and formed, It becomes easy to join and the connection reliability can be improved.

Further, in the present invention, a resin-coated metal foil in which a B-stage-shaped thermosetting resin is applied to the metal foil is used.
The thermosetting resin layer applied to this metal foil is an epoxy resin, an imide resin, a polyester resin, a phenol resin,
It is formed of a thermosetting resin such as a polyphenylene oxide-containing thermosetting resin, and if necessary, an inorganic powder filler or the like is used. As this thermosetting resin layer, one coated at least one layer is used.

As a method for applying the above-mentioned thermosetting resin to the surface of the metal foil, a liquid thermosetting resin varnish is applied by a comma coater, a transfer coater or a curtain coater, and is continuously or discontinuously heated and dried. It is formed by curing and B-stage.

The thermosetting resin layers applied in plural layers are preferably applied by changing the softening temperature of each resin layer. It is preferable that the thermosetting resin layers are softened at a high temperature as they approach the metal foil side. As a method of changing the softening temperature of the thermosetting resin layer, there is a method of heating each time the thermosetting resin layer is applied. In this way, by changing the softening temperature of each resin layer, the convex conductive portion can easily penetrate the resin layer at the time of laminate molding.

Further, in the thermosetting resin composition constituting the first resin layer, particles having conductivity such as graphite, whiskers, carbon, and conductive metal particles such as gold, silver and copper are added. It is preferable to contain, by containing particles having such conductivity, when the conductive part having a convex shape through lamination molding penetrates the resin layer, the particle having the conductivity has a convex conductivity. The part is pushed up to the metal foil surface, and takes part in electrical connection between the metal foil and the convex conductive part.

Further, when the resin-coated surface of the metal foil before the thermosetting resin is coated with gold, the top of the conductive portion comes into contact with the gold-plating and metal-bonds when laminated and molded. It becomes easier and the connection reliability can be improved.

An inner layer substrate having a wiring pattern formed with a convex conductive portion at a position requiring electrical connection formed as described above, and a resin-coated metal foil having two resin layers formed thereon. Are laminated and multi-layered by heating and pressing,
Further, an outer layer circuit was formed and a finishing process was performed to obtain a multilayer printed wiring board.

1 and 2 are cross-sectional views of a resin-coated metal foil and an inner layer substrate before lamination molding according to an embodiment of the present invention.

As shown in the figure, in the method for manufacturing a multilayer printed wiring board according to the present invention, first, the inner layer substrate 3 having the wiring patterns 2 formed on the front and back sides is prepared, and the surface of the wiring pattern 2 of the inner layer substrate 3 is prepared. Then, the convex conductive portion 4 is formed at a position where electrical connection with other layers is required.

Further, a resin-coated metal foil 5 to be laminated on the upper and lower surfaces of the inner layer substrate 3 is prepared. The resin-coated metal foil 5 has a surface of a metal foil 6 coated with a first resin layer 7 composed of a thermosetting resin varnish, and the thermosetting resin varnish is applied onto the first resin layer 7. The second resin layer 8 composed of is applied.

The thermosetting resin composition forming the first resin layer 7 preferably contains particles having conductivity as described above.

FIG. 2 shows the inner layer substrate 3 in which the convex conductive portions 4 are formed on the surface of the wiring pattern 2 as in FIG.
A gold plating 9 is applied to the top of the convex conductive portion 4. Also, the metal foil with resin 5
Before applying the first resin layer 7, the metal foil 5 is plated with gold 1
What was given 0 was used.

These are used as the body to be pressed 1 and laminated molding is performed.
FIG. 3 is a cross-sectional view of the inner layer substrate and the resin-coated metal foil of FIG. 1 laminated and molded.

As shown in the figure, the convex conductive portion 4 formed on the surface of the wiring pattern 2 of the inner layer substrate 3 is coated with the resin-coated metal foil 5, and the first and second resin layers 7, 8 and is bonded to the metal foil 6 to form a conductive path 11. Then, a circuit pattern is formed on the surface metal foil 5 to form a multilayer printed wiring board.

[0039]

EXAMPLES AND COMPARATIVE EXAMPLES The present invention is described below based on Examples and Comparative Examples, but these Examples do not limit the present invention in particular.

First, a wiring pattern is formed on one surface of a FR-4 type double-sided copper-clad laminate (laminate thickness 1.0 mm, copper foil thickness 18 μm), and a copper foil is formed on the other surface. The entire surface was removed by etching to prepare an inner layer substrate on which a wiring pattern was formed, and the surface of this wiring pattern was subjected to a surface treatment called blackening treatment.

Then, for the production of FR-4 type laminated plate containing a bisphenol A type epoxy resin and dicyandiamide as main components with respect to an electrolytic copper foil for electrical use (GT-18 μm manufactured by Furukawa Circuit Co., Ltd.) having a thickness of 18 μm. The epoxy resin varnish used was applied and cured using a comma coater as shown in the following examples to form a resin-coated copper foil.

Further, a convex conductive portion was formed at a position requiring electrical connection with the upper layer of the inner layer substrate on which the above wiring pattern was formed. (Example 1) The resin-coated copper foil has a thickness after drying of 50 μm.
Epoxy resin varnish so that
It was dried for 20 minutes and semi-cured (B-staged).

The convex conductive portion is formed by printing a copper paste, which is softened at 130 ° C. to 170 ° C., at a position where electrical inter-layer connection of the double-sided copper clad laminate on which a wiring pattern has been formed is required, by a printing method. 80 μm, the diameter of the lower surface is 100 μm
It was printed and cured in a conical shape so that (Example 2) The resin-coated copper foil has a thickness after drying of 30 μm.
To coat the epoxy resin varnish so that
Formed by drying for 30 minutes and semi-curing (B-stage), then applying epoxy resin varnish to a thickness of 30 μm, drying at 130 ° C. for 20 minutes and semi-curing (B-stage). did.

The convex conductive portion is formed with a wiring pattern at a position where electrical interlayer connection of the double-sided copper clad laminate is required,
A copper paste softening at 130 ° C. to 170 ° C. was printed and hardened by a printing method in a conical shape so that the height was 40 μm and the diameter of the lower surface was 50 μm. (Example 3) The resin-coated copper foil has a thickness after drying of 50 μm.
130 ° C by applying epoxy resin varnish so that
It was dried for 20 minutes and semi-cured (B-staged).

The convex conductive portion is formed by printing a silver paste which is softened at 130 ° C. to 170 ° C. by a printing method at a position where electrical interlayer connection of a double-sided copper clad laminate having a wiring pattern is required. 80 μm, the diameter of the lower surface is 100 μm
It was printed and cured in a conical shape so that (Example 4) The resin-coated copper foil has a thickness after drying of 30 μm.
To coat the epoxy resin varnish so that
It is dried for 30 minutes, semi-cured (B stage), and then re-coated so that the thickness becomes 30 μm.
It was formed by semi-curing (B-stage) by drying at 20 ° C. for 20 minutes.

The convex conductive portion is formed by printing a gold paste that is softened at 130 ° C. to 170 ° C. by a printing method at a position where electrical interlayer connection of the double-sided copper clad laminate having a wiring pattern formed thereon is required. Was 40 μm, and the diameter of the lower surface was 50 μm. (Example 5) The resin-coated copper foil has a thickness after drying of 50 μm.
130 ° C by applying epoxy resin varnish so that
It was dried for 20 minutes and semi-cured (B-staged).

In the convex conductive portion, a solder ball having a diameter of 100 μm was formed at a position where electrical interlayer connection of the double-sided copper clad laminate having a wiring pattern formed thereon was required. (Example 6) The resin-coated copper foil was plated with gold to a thickness of 0.10 μm on the resin-coated surface of the copper foil in advance, and then an epoxy resin varnish was applied so that the thickness after drying was 30 μm. It is applied and dried at 150 ° C for 30 minutes and then semi-cured (B stage). Further, an epoxy resin varnish is applied so that the thickness becomes 30 µm, and dried at 130 ° C for 20 minutes and semi-cured (B Formed into a stage).

The convex conductive portion is formed by printing a copper paste which is softened at 130 to 170 ° C. by a printing method at a position where electrical interlayer connection of the double-sided copper clad laminate having a wiring pattern is required. Is 40 μm and the lower surface has a diameter of 50 μm. (Example 7) The resin-coated copper foil was coated with an epoxy resin varnish so that the thickness after drying was 50 μm, and the temperature was set to 130 ° C.
It was dried for 0 minutes and semi-cured (B-staged).

The convex conductive portion is formed with a wiring pattern, and the double-sided copper clad laminate is provided at a position where electrical interlayer connection is required.
A copper paste that softens at 130 ° C. to 170 ° C. was printed in a conical shape by a printing method so that the height was 80 μm and the lower surface was 100 μm in diameter, and after curing, gold was plated to a thickness of 0.10 μm. (Example 8) The resin-coated copper foil has a thickness after drying of 30 μm.
The epoxy resin varnish containing graphite having electrical conductivity is applied and dried at 150 ° C. for 30 minutes to be semi-cured (B stage), and the epoxy resin varnish to have a thickness of 30 μm. Coated at 130 ℃, 2
It was dried for 0 minutes and semi-cured (B-staged).

The convex conductive portion is provided with a wiring pattern, and the double-sided copper clad laminate is provided at a position where electrical inter-layer connection is required.
A copper paste that softens at 130 ° C. to 170 ° C. was printed and hardened by a printing method in a conical shape so that the height was 40 μm and the diameter of the lower surface was 50 μm.

Similarly to Example 1 on both surfaces of the inner layer material on which the wiring pattern and the columnar paste shown in Examples 1 to 8 are formed.
The resin-coated copper foils shown in FIGS. 8 to 8 were arranged as pressure-receiving bodies, and the pressure-receiving bodies were further sandwiched by stainless plates, and multilayer molding was performed under the following conditions.

In Examples 1, 2, 3, 7, and 8, 100
The second resin layer of the copper foil with resin melts and flows under the condition of 5 ° C and 5 kg / cm ² to embed the inner layer circuit pattern, and then the first resin under the condition of 15 kg / cm ² at 130 ° C. The layer was softened and heated and pressed so that the above-mentioned columnar paste penetrated the first applied resin layer.

As a result, the columnar paste makes an electrical connection between the layers, the first resin layer ensures electrical insulation between layers other than the columnar paste portion, and the second resin layer ensures the moldability of the inner layer circuit. It

The multilayer board molded under the above conditions was further subjected to outer layer circuit formation and finishing to obtain PWB. (Comparative Example) A wiring pattern is formed on both sides of an FR-4 type double-sided copper-clad laminate (laminate thickness: 1.0 mm, copper foil thickness: 18 μm), and then the surface of the wiring pattern is referred to as a blackening treatment. The treatment was performed to produce an inner layer substrate on which a wiring pattern was formed.

Further, a copper paste was printed and hardened by a printing method at a position requiring electrical connection with the upper layer of the inner layer wiring pattern into a conical shape having a height of 250 μm and a lower surface of 300 μm in diameter.

Further, an electrolytic copper foil for electrical use (GT-18 μm, manufactured by Furukawa Circuit Co., Ltd.) having a thickness of 18 μm and a glass woven cloth-based epoxy resin prepreg having a thickness of 0.2 mm were prepared.

One prepreg was placed on each side of the inner layer substrate on which the above-mentioned wiring pattern was formed, copper foil was further placed, and the sheets were sandwiched between stainless plates, and multilayered molding was performed under the following conditions. .

Molding was carried out under conditions of 100 ° C. and 5 kg / cm ² for 5 minutes.
After holding for 0 minutes, it is completely cured at 180 ° C. under the condition of 30 kg / cm ² , and the multilayer molding is completed.

The multilayer board molded under the above conditions was further subjected to outer layer circuit formation and finishing to obtain PWB.

The PWBs obtained in Examples 1 to 8 and Comparative Example were evaluated as follows, and the results are shown in Table 1.

Total work man-hours: Time man-hours when the comparative example is 100 Total manufacturing cost: Cost when the comparative example is 100 Inter-layer insulation thickness: Average thickness of insulating layer Defect ratio during molding: Defect ratio occurring during molding Inter-layer connection Failure rate: Connection failure rate of upper and lower interlayer conductive paths Thermal cycle test: -60 ° C, 120 ° C cycle test Inner layer circuit formability: Minimum inner circuit width and circuit spacing Surface layer circuit formability: Surface layer Minimum formable circuit width and circuit spacing

[0062]

[Table 1]

[0063]

According to the method for manufacturing a multilayer printed wiring board of the present invention, a resin layer as an insulating layer can be uniformly formed, and the penetration of the convex conductive portion is very stable. become. Also, without destroying the reinforcing material such as glass woven cloth,
The occurrence of defects due to breakage of the insulating layer can also be suppressed,
Furthermore, the insulating layer formed on the metal foil by coating can easily form an insulating thickness of 30 to 50 μm, and the convex conductive portion is inevitably small, so that a fine circuit can be formed. It also has an effect on sex.

Further, during the laminated molding, the convex conductive portion easily penetrates the resin layer softened by the high temperature during molding to reach the outer copper foil to secure the electrical connection between the inner layer and the outer layer. Further, since the glass fiber is not broken, the occurrence of defects at the initial stage and after heating is suppressed, and the reliability can be improved.

Further, the total work man-hours and the total manufacturing cost are reduced, and since the panel plating is not performed, the surface fine circuit formability can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a body to be pressed according to an example showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a body to be pressed according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view of an example showing the embodiment of the present invention, which is formed by laminating.

[Explanation of symbols]

 1 Pressure Target 2 Wiring Pattern 3 Inner Layer Substrate 4 Convex Conductive Part 5 Metal Foil with Resin 6 Metal Foil 7 First Resin Layer 8 Second Resin Layer 9 Gold Plating 10 Gold Plating 11 Conductive Path

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[Procedure amendment]

[Submission date] April 1, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 10

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

According to a tenth aspect of the present invention, in the method for producing a multilayer printed wiring board, the anisotropically conductive resin composition comprises whiskers, carbon, and conductive particles such as conductive metal particles. It is a resin composition containing any of the above.

Claims (10)

[Claims] 1. A convex conductive portion is previously formed on a surface of an inner layer substrate on which a wiring pattern is formed at a position where electrical conduction between layers is intended, and a metal foil is laminated and formed with an insulating layer interposed therebetween. In a method for manufacturing a multilayer printed wiring board, wherein the convex conductive portion penetrates an insulating layer to establish electrical conduction between layers, a thermosetting resin in a B stage state that melts at high temperature is applied to the metal foil. To form a resin-coated metal foil having an insulating layer formed thereon, and to laminate-mold the inner layer substrate on which the convex conductive portion is formed and this resin-coated metal foil. Production method. 2. A convex conductive portion is previously formed on a surface of the inner layer substrate on which a wiring pattern is formed at a position where electrical conduction between layers is achieved, and a metal foil is laminated and formed with an insulating layer interposed therebetween. In the method for manufacturing a multilayer printed wiring board, wherein the convex conductive portion penetrates an insulating layer to establish electrical conduction between the layers, in which the metal foil is melted at a low temperature with a first resin layer which is softened at a high temperature. A second resin layer is applied to form an insulating layer-formed metal foil with resin, and the inner layer substrate on which the convex conductive portion is formed and the metal foil with resin are laminated and formed. A method for manufacturing a characteristic multilayer printed wiring board. 3. The method for producing a multilayer printed wiring board according to claim 1, wherein the convex conductive portion is formed by using a metal paste and / or a metal molded body. 4. The method for manufacturing a multilayer printed wiring board according to claim 3, wherein the metal paste and / or the metal molded body is formed of a simple substance of gold, silver or copper or an alloy thereof. 5. The method according to claim 1 or 2, wherein the convex conductive portion is formed by using solder.
A method for producing the multilayer printed wiring board according to the above. 6. The method of manufacturing a multilayer printed wiring board according to claim 1, wherein the top of the convex conductive portion is plated with gold. 7. The multi-layer print according to claim 1, wherein the resin-coated metal foil is formed by gold-plating a resin-coated surface and then coating the resin thereon. Wiring board manufacturing method. 8. The multilayer printed wiring board according to claim 1, wherein the resin layer forming the metal foil with resin is formed of a resin composition having anisotropic conductivity. Production method. 9. A method for manufacturing a multilayer printed wiring board, wherein the first resin layer constituting the resin-coated metal foil according to claim 2 is formed of a resin composition having anisotropic conductivity. Method. 10. The resin composition having anisotropic conductivity is a resin composition containing any one of graphite, whiskers, carbon, and conductive particles of conductive metal particles. The method for manufacturing a multilayer printed wiring board according to claim 8 or 9.