JP2954163B1 - Method for manufacturing multilayer printed wiring board - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing a multilayer printed wiring board having a flat insulating layer surface and less likely to generate voids. SOLUTION: In a method for manufacturing a build-up multilayer printed wiring board, when applying a light or thermosetting resin, particularly an ultraviolet curable resin, as an undercoat 4 to an inner layer substrate,
The coating is applied separately on one surface and the other surface of the inner substrate 3 in which the via holes 2 are formed, and the via holes 2 are filled from both sides to eliminate voids and flatten the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a multilayer printed wiring board, and more particularly, to a method for manufacturing a build-up multilayer printed wiring board.

[0002]

2. Description of the Related Art Conventionally, build-up multilayer printed wiring boards have been manufactured as follows. First, the formation of the inner layer substrate is obtained by heat-pressing a copper-clad laminate, a prepreg, and a copper foil on which a circuit is formed by a lamination press. Drilling is performed at a desired position on the inner layer substrate by drilling or the like, and copper plating is performed to connect the layers. In order to uniformly apply the build-up resin on the inner substrate, the via holes are filled with a thermosetting resin, and after curing by baking, the substrate surface is polished and smoothed. Next, after forming a circuit on the surface layer of the inner layer substrate, a build-up resin is applied, a via hole is formed, plating is performed, and an outermost layer circuit is formed.

[0003] The above-mentioned method involves the problem that the thickness of the inner conductor is fluctuated due to polishing, and the dimensional fluctuation of the inner substrate is large. A manufacturing method that overcomes these problems has been disclosed.

[0004] As an example, Japanese Patent Application Laid-Open No. 7-202433 is disclosed.
JP-A No. 5-2, a manufacturing method in which a liquid filler is supplied to an inner layer substrate, and a film-like adhesive sheet is laminated thereon.
7 and 8 are diagrams showing, as an example, a method of manufacturing a four-layer build-up multilayer printed wiring board in the order of steps (a) to (h).

First, as shown in FIGS. 7 (a), 7 (b) and 7 (c), an inner substrate 3 having via holes 2 and patterns formed in a copper-clad laminate 1 by a known subtractive method.
Is roughened by a blackening treatment. The purpose of this blackening treatment is to improve the adhesion of the build-up resin. The inner substrate 3 has a hole diameter of 0.2 mm.

Next, as shown in FIG. 7D, an ultraviolet curable resin 11 is applied to both surfaces of the inner layer substrate by dipping, a roll coater or the like. Further, FIG.
As shown in (e), a film-shaped ultraviolet curable resin sheet 12 (hereinafter referred to as a resin sheet) having a thickness of 40 μm is rolled on the inner layer substrate under a reduced pressure of 2-3 torr and a roll temperature of 8.
Thermocompression bonding is performed by roll lamination at 0 ° C. and a roll pressure of 3 kgf / cm ² to form a four-layer laminate having an insulating interlayer thickness of 40 μm. Thereafter, as shown in FIG.
The ultraviolet curable resin 11 and the resin sheet 12 are cured by exposing at 00 mJ, and the ultraviolet curable resin 13 cured by exposure is obtained. Next, as shown in FIG. 8G, the cured ultraviolet curing resin 13 is subjected to development, UV curing, and heat treatment to form holes 14 by photolithography. After roughening the surface with chromic acid as shown in FIG. 8 (h), a palladium catalyst was applied thereto, and a dry film resist having a resin thickness of 40 μm was thermocompressed.
Exposure, development, UV curing and heat treatment are performed and the resist layer 15
Is formed and subjected to an electroless copper plating treatment with a plating thickness of 25 μm to manufacture the build-up multilayer printed wiring board 10 having the photovia hole 16.

[0007]

In the above-mentioned conventional example,
When the insulating layer is formed by roll lamination of the resin sheet under reduced pressure after the simultaneous application of the photosensitive liquid resin on both sides, a depression is generated on the surface of the insulating layer. If there is a depression in the insulating layer,
When a circuit is formed by photolithography on the surface layer of a build-up multilayer printed wiring board, the exposure of the photosensitive resist resin layer (formed by roll lamination of a dry film or application of a liquid resin) causes the adhesion between the pattern film and the resin surface However, there is a problem that various patterns such as short-circuit and disconnection due to blur occur.

When a circuit is formed on the surface layer by additive plating, the surface of the build-up multilayer printed wiring board is roughened, catalyzed, and exposed after forming a photosensitive resist. Blur occurs due to reduced adhesion to the pattern film,
This causes a problem that a pattern abnormality occurs.

As described above, the reason why the flattening cannot be performed by the conventional method is that the inside of the via hole is
And the surrounding photosensitive liquid resin flows through the front and back. If the resin in this portion is insufficient, a dent of the insulating layer will occur due to this.

[0010] The second problem is that voids are easily generated inside the via hole. That is, the through-hole or SVH (Surfac) after the build-up resin layer is formed.
In the plating of e-Via-Hole), there is a possibility that the plating solution may permeate into the voids, thereby causing a problem of short-circuiting of the plating and a failure due to a residue of the plating solution.

[0011] As described above, the reason why voids are generated in the conventional method is that when the resin is simultaneously filled into the via hole on both sides, bubbles in the via hole are difficult to escape, and the resin may be cured while the bubbles remain. That's why.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer printed wiring board having a flat insulating layer surface and less likely to cause voids.

[0013]

In order to achieve the above object, a multilayer printed wiring board according to the present invention comprises a method of manufacturing a build-up multilayer printed wiring board comprising an inner layer substrate having via holes and patterns formed thereon. On one side of the board
Step of applying photocurable resin and from the other side of the inner layer substrate
UV curing to cure the photo-curable resin in the via hole
And applying a photocurable resin to the other side of the inner layer substrate.
The generation of voids inside the via holes.
It is characterized by prevention .

Preferably, the photocurable resin is an ultraviolet curable resin.

Furthermore, a step of applying an ultraviolet curable resin to one surface of the inner layer substrate having the via hole and the pattern formed thereon and filling the via hole with the ultraviolet curable resin; Curing the UV curable resin on one surface of the inner layer substrate again, and curing the applied surface again with UV light, applying the UV curable resin on the other surface of the inner layer substrate, and applying UV light to the applied surface. A step of curing, a step of removing moisture absorption of the ultraviolet curable resin by baking treatment of the inner layer substrate, and a step of smoothing the surface of the ultraviolet curable resin by leveling, and a step of laminating a copper foil with an adhesive resin on the inner layer substrate by a roll laminator. It is preferable to include a step of thermocompression bonding and a step of thermosetting a copper foil with an adhesive resin to form a copper-clad laminate with an inner layer circuit.

Furthermore, it is preferable that the surface of the copper foil of the copper-clad laminate is immersed in a mixed solution of sodium chlorite and caustic soda to be subjected to needle crystallization.

A step of etching the entire surface of the surface copper foil of the copper-clad laminate containing the inner layer circuit; a step of irradiating the ultraviolet curable resin with a carbon dioxide laser or an excimer laser to form a laser hole; It is preferable that the method further includes a step of forming a laser via hole by plating the hole with a copper panel, and a step of forming an outermost layer pattern by etching the outermost layer of the inner substrate.

Further, there is a coating condition under which the ultraviolet curable resin infiltrates into the via hole by a capillary phenomenon, and
It is preferable to have a resin viscosity suitable for this.

Further, it is preferable to apply the ultraviolet curable resin only around the visa hole.

Preferably, the via hole is a through-hole.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a first embodiment of the present invention will be described with reference to FIGS. (A) to (n)
Will be described in the order of steps.

First, as shown in FIGS. 1 (a), 1 (b) and 1 (c), a hole is formed in a copper-clad laminate 1 composed of a copper foil and a base material, and the hole is plated. 0.2-0.
An 8 mm via hole 2 is formed, and a pattern is formed by etching the copper clad laminate 1 to form an inner layer substrate 3. next,
The pattern surface of the inner layer substrate 3 is blackened with a strong alkali. By immersing the surface of the copper foil in a mixed solution of sodium chlorite and caustic soda for 3 to 10 minutes, the surface of the copper foil is needle-like crystallized, and the adhesion of the resin applied in the next step is improved.

Next, as shown in FIG. 1D, an ultraviolet-curable undercoat resin 4 is applied to one entire surface of the inner substrate 3 by using a screen printing method. The screen printing conditions at this time are as follows: screen mesh is 80 to 100 mesh, squeegee hardness is 70 degrees, application speed is 0.1 to 100 mesh.
0.05 m / sec. The undercoat resin 4 has a viscosity of 10 to 30 poise at 20 ° C., a TI value of 1.0 to 1.5, and an exposure amount of ultraviolet light of 1 to 3 J / cm.
^{A material having a} curing temperature of about 80 to 100 ° C. and a melt viscosity of 10,000 to 50,000 poise when heated after being cured (hereinafter referred to as UV cure) and heated after UV cure is used. In order to prevent air bubbles from being mixed into the resin layer after the final curing, it is a necessary condition that the undercoat resin 4 is a solventless type. Table 1 shows an example of such an undercoat resin 4.

[0024]

[Table 1]

The undercoat resin is a liquid bisphenol A epoxy resin as an epoxy resin, a bisphenol A epoxy acrylate as an acrylate resin,
Novolak type epoxy acrylate, 2-ethyl-4-methylimidazole and 2-methylimidazole as epoxy resin curing agents, 1-hydroxycyclohexyl acetophenone, 2,2-dimethoxy- as photopolymerization initiator
1,2-diphenylethan-1-one can be used.

In the case of UV curing, it takes 15 to 60 minutes after application of the resin in order to improve the surface smoothness and defoam. The coating conditions such as the squeegee angle and the screen gap are set in accordance with the diameter of the via hole, and the resin thickness after UV curing on the substrate without the via hole and the pattern (hereinafter referred to as resin thickness) is shown in Table 2. Adjust so that

[0027]

[Table 2]

That is, when the via hole diameter is φ0.2 to 0.2.
If it is 5 mm, the resin thickness of the first application is 20 μm, the resin thickness of the second application is 25 μm, and the via hole diameter is φ0.5.
If it is ~ 0.8 mm, the resin thickness of the first application is 30 μm,
The resin thickness of the second application is 25 μm.

Next, as shown in FIG. 1E, UV curing is performed under the conditions of an exposure amount of ultraviolet light of 1 to 3 J / cm ² . At this time, only the under lamp 5 in the via hole is UV-cured by operating only the lower lamp in a conveyor-type double-side UV curing furnace so as to irradiate only the back surface of the application surface. Since the resin penetrates into the via hole, the above-mentioned coating surface lacks the resin around the via hole, and φ
Approximately 20 μm at 0.2 to 0.5 mm, 0.5 to 0.8 m
A depression of about 30 μm occurs at m.

Next, as shown in FIG. 1F, a second application of the undercoat resin 4 is performed by screen printing on the entire surface of the substrate on which the dents have occurred, and the portions where the dents have occurred are buried. This coating is performed under the coating conditions shown in Table 2. As a result, the resin thickness after the second application is 20 μm or more as the resin thickness on the pattern after UV curing. The reason why the resin thickness on the pattern is required to be 20 μm is that, by averaging the resin thickness between the resin thickness on the pattern and the resin thickness on the base material, air is entrapped in the copper foil sheet lamination in a later step, and voids are formed. This is to prevent that.

Similarly, as shown in FIG. 1 (g), an undercoat resin 4 is applied by screen printing on the entire surface of the substrate on which the resin is not applied. The application conditions are adjusted so that the resin thickness at this time is 20 to 25 μm.

Next, as shown in FIG. 2H, the inner layer substrate 3 is subjected to a UV curing process, and
A baking treatment is performed at a temperature of 20 ° C. for a heating time of 20 to 30 minutes to perform leveling of the undercoat resin surface and removal of moisture-absorbing components.

Next, in order to secure adhesion to the copper foil sheet 6 to be thermocompressed in FIG. 2 (i), it is assumed that the surface of the undercoat resin is melted during thermocompression, but the resin is baked. It is necessary to adjust the curing level because the heat curing proceeds and the melting becomes difficult due to the treatment. In addition, since the thermosetting reaction also proceeds during UV curing, the conditions were set as shown in Table 3 in association with the ultraviolet irradiation conditions and the baking conditions.

[0034]

[Table 3]

As shown in Table 3, the amount of UV light exposure 1,2,2
For 3 J / cm ² , the baking conditions include a heating time and a substrate surface temperature of less than 25 minutes, 80 ° C. or more and less than 20 minutes, a rise in temperature, less than 15 minutes, and a rise in temperature.

It has been confirmed that by curing under these conditions, it is possible to prevent excessive resin curing that inhibits the adhesion reaction during lamination.

Further, as shown in FIG. 2 (i), a copper foil sheet 6 is thermocompression-bonded by roll lamination to the baked inner layer substrate to form a four-layer laminate. In addition, in order to prevent moisture absorption, the inner layer substrate after baking is at 20 to 25 ° C and 50 to 25 ° C.
The thermocompression bonding of the copper foil sheet 6 is performed within 2 hours in an atmosphere of 60% RH (relative humidity). In order to improve the adhesion, the surface temperature of the inner substrate (the surface temperature of the undercoat resin) before lamination is increased to 70 to 90 ° C. by a method such as IR (infrared) heating or roll heating. The lamination conditions are as follows: lamination roll temperature 100 to 120 ° C, lamination pressure 3 to 6 kg /
cm ² and a lamination speed of 0.3 to 1.0 m / min.

Next, as shown in FIG. 2 (j), the laminate is subjected to a heat treatment at 140 to 160 ° C. for 30 to 60 minutes to obtain a highly reliable copper having an inner layer circuit with a flat surface. After that, as shown in FIG. 2 (k), the entire surface of the surface copper foil of the copper-clad laminate 7 with the inner layer circuit is subjected to an etching treatment. Next, as shown in FIG. 2 (l), a laser hole 8 is formed by a carbon dioxide laser or an excimer laser. Thereafter, as shown in FIG. 3 (m), copper panel plating is performed to form a laser via hole 9. Further, as shown in FIG. 3 (n), an outermost layer pattern is formed by an etching process to obtain a build-up multilayer printed wiring board 10.

Next, a second embodiment of the present invention will be described with reference to FIGS. (A) to (n) will be described in the order of steps.

First, as shown in FIGS. 4 (a), 4 (b) and 4 (c), in order to improve the adhesiveness with the undercoat resin applied to the surface in the next step, it is composed of a copper foil and a base material. A hole is formed in the copper-clad laminate 1, and a via hole 2 is formed by plating, the pattern is formed, and the formed inner layer substrate 3 is formed.
Is blackened.

Next, as shown in FIG. 4D, a UV-curable and solventless type undercoat resin 4 is applied to one surface of the inner layer substrate by using a screen made so that only the periphery of the via hole 2 can be coated. Screen print. Next, as shown in FIG. 4 (e), the undercoat resin 4 in the via hole 2 is irradiated with ultraviolet rays only on the back surface of the coating surface.
Is subjected to UV curing to obtain an undercoat resin 5 after UV curing. At this time, the screen printing conditions are as follows: screen mesh is 80 to 100 mesh, squeegee hardness is 70.
And the coating speed is 0.1 to 0.05 m / sec. The undercoat resin 4 has a viscosity of 10 to 30 at 20 ° C.
Poise, TI value 1.0 to 1.5, UV irradiation dose 1
A substance which has a melting start temperature of about 80 to 100 ° C. and a melt viscosity of 10,000 to 50,000 poise when it is cured at 3 J / cm ² and heated after ultraviolet curing is used. 15 after resin application to improve surface smoothness and defoam
After a leaving time of 分 の 60 minutes, an exposure amount of 1 to 3 J / cm
UV cure under the conditions of ² . The application conditions are set so that “the resin thickness on the substrate in a single application to the substrate without via holes and patterns” has the value shown in Table 2. Thereafter, as shown in FIG. 4 (f), the undercoat resin 4 is again applied to the above-mentioned application surface by using a screen made in a solid pattern so that it can be applied to the entire substrate. As shown in FIG. 4 (g), the undercoat resin 4 is applied by screen printing to one surface on which no resin is applied, as shown in FIG. 4 (g).

Next, as shown in FIG. 5H, the undercoat resin 4 is UV cured. The solid pattern application conditions are set so that the resin thickness of both sides is the condition of the values in Table 2. After the UV curing, the inner layer substrate shown in FIG. 5H is baked at a temperature of 80 to 120 ° C. for a heating time of 20 to 30 minutes to level the undercoat resin surface and remove moisture-absorbing components. .
The baking conditions are set according to Table 3 in order to prevent excessive resin curing that inhibits lamination adhesion. Next, as shown in FIG. 5 (i), the copper foil sheet 6 is thermocompression-bonded to the inner layer substrate after the heat treatment by roll lamination to form a four-layer laminate. The inner substrate after baking is subjected to thermocompression bonding of the copper foil sheet 6 within 2 hours in an atmosphere of 20 to 25 ° C. and 50 to 60% RH. In order to improve adhesion, the surface temperature of the inner layer substrate (the surface temperature of the undercoat resin) before lamination is increased to 70 to 90 ° C. by a method such as IR heating or roll heating. Roll lamination conditions are lamination roll temperature 100 to 120 ° C. and lamination pressure 3 to 6.
kg / cm ² , lamination speed 0.3-1.0m /
Set to minutes. As a final curing, as shown in FIG. 5 (j), a heat treatment is performed at 140 to 160 ° C. for 30 to 60 minutes to obtain a copper-clad laminate 7 with an inner layer circuit. Next, FIG.
As shown in (k), all the copper foils on both sides of the copper-clad laminate 7 with the inner layer circuit are etched. FIG. 5 (l) shows the laser hole 8 formed as a result of the etching. FIG.
In (m), a copper via plating is performed to form a laser via hole 9. Further, in FIG. 6 (n), etching and pattern formation are performed by a photolithography method to obtain a build-up multilayer printed wiring board 10.

Note that the via holes described above correspond to the IVH
Needless to say, the present invention can be applied to (Interstitial Via Hall).

As a result, as shown in Table 4, in the conventional example of simultaneous coating on both sides described in JP-A-7-202433, the surface dent of the insulating layer (the surface dent of the via hole of φ0.4 mm) was 10 to 10%. According to the method of the present invention, it is 5 to 10 μm for 20 μm.

[0045]

[Table 4]

Note that this value is obtained by measuring the unevenness difference between the inner layer via hole portion and the inner layer circuit portion on the insulating layer surface.

[0047]

According to the present invention, a flat surface of the insulating layer can be obtained, whereby the pattern formation abnormality such as short circuit or disconnection can be reduced by 5 to 20%.

In addition, the generation of resin voids in the via holes is prevented from 30% to 50% to about 5%, so that there is an effect that a short circuit caused by voids can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a manufacturing process of a first embodiment of the present invention. (A) is a cross-sectional view of the copper-clad laminate before processing, (b)
Is a cross-sectional view of the inner layer substrate after the formation of the via hole, (c) is a cross-sectional view of the inner layer substrate after the circuit is formed, (d) is a cross-sectional view showing the first undercoat coating, and (e) is a UV cure from the back surface of the coating. FIG. 7F is a cross-sectional view showing a second undercoat application, and FIG. 8G is a cross-sectional view showing an undercoat application on an uncoated surface.

FIG. 2 is a sectional view illustrating a manufacturing process of the first embodiment of the present invention. (H) is a cross-sectional view showing UV curing, (i) is a cross-sectional view showing lamination of a copper foil sheet, (j) is a cross-sectional view showing post-baking, (k) is a cross-sectional view showing etching of an outer layer copper foil, 1) is a sectional view showing the formation of a laser hole.

FIG. 3 is a cross-sectional view showing a manufacturing process of the first embodiment of the present invention. (M) is a sectional view showing plating of the outermost layer, (n)
FIG. 4 is a cross-sectional view showing a build-up multilayer printed wiring board in which the outermost layer is patterned by photolithography.

FIG. 4 is a cross-sectional view illustrating a manufacturing process according to a second embodiment of the present invention. (A) is a cross-sectional view of the copper-clad laminate before processing, (b)
Is a cross-sectional view of the inner layer substrate after the formation of the via hole, (c) is a cross-sectional view of the inner layer substrate after the formation of the circuit, (d) is a cross-sectional view showing the first undercoat application to the via hole portion, and (e) is a cross-sectional view from the back side of the application. FIG. 7F is a cross-sectional view showing UV curing, FIG. 7F is a cross-sectional view showing a second undercoat application, and FIG. 7G is a cross-sectional view showing an undercoat application on an uncoated surface.

FIG. 5 is a sectional view showing a manufacturing process according to a second embodiment of the present invention. (H) is a cross-sectional view showing UV cure, (i) is a cross-sectional view showing lamination of a copper foil sheet, (j) is a cross-sectional view showing post-baking, (k) is a cross-sectional view showing etching of an outer layer copper foil, (L) is a sectional view showing the formation of a laser hole.

FIG. 6 is a sectional view illustrating a manufacturing process according to a second embodiment of the present invention. (M) is a sectional view showing plating of the outermost layer, (n)
FIG. 4 is a cross-sectional view showing a build-up multilayer printed wiring board in which the outermost layer is patterned by photolithography.

FIG. 7 is a cross-sectional view illustrating a manufacturing process of a conventional example. (A)
Is a cross-sectional view of the copper-clad laminate before processing, (b) is a cross-sectional view of the inner substrate after forming the via hole, (c) is a cross-sectional view of the inner substrate after forming the circuit, and (d) is both surfaces of the ultraviolet curable resin. FIG. 3E is a cross-sectional view illustrating application, FIG. 4E is a cross-sectional view illustrating lamination of an ultraviolet-curable resin sheet, and FIG. 4F is a cross-sectional view illustrating ultraviolet exposure by photolithography.

FIG. 8 is a sectional view showing a manufacturing process of a conventional example. (G)
FIG. 4 is a cross-sectional view showing the formation of holes by development, and FIG. 4H is a cross-sectional view showing a build-up multilayer printed wiring board in which a resist layer is formed on the outermost layer and a pattern is formed by plating.

[Description of Signs] 1 Copper-clad laminate 2 Via hole 3 Inner substrate 4 Undercoat resin 5 Undercoat resin after UV curing 6 Copper foil sheet 7 Copper-clad laminate with inner layer circuit 8 Laser hole 9 Laser via hole 10 Build-up multilayer printing Wiring board 11 UV-curable resin 12 UV-curable resin sheet 13 UV-curable resin cured by exposure 14 Hole by photolithography method 15 Resist layer 16 Photo via hole

Claims (8)

(57) [Claims] 1. A method of manufacturing a build-up multilayer printed wiring board comprising an inner layer substrate having a via hole and a pattern formed thereon, wherein a photocurable resin is applied to one surface of the inner layer substrate.
And irradiating ultraviolet light from the other side of the inner layer substrate to form the via hole.
Curing the photo-curable resin in the tool and applying the photo-curable resin to the other surface of the inner layer substrate.
And preventing generation of voids inside the via hole.
A method for manufacturing a build-up multilayer printed wiring board, wherein the method is stopped . 2. The method according to claim 1, wherein the photocurable resin is an ultraviolet curable resin. 3. A step of applying the ultraviolet curable resin to one surface of the inner substrate on which the via hole and the pattern are formed, and filling the via hole with the ultraviolet curable resin; and the other surface of the inner substrate. Curing the ultraviolet-curable resin from above; applying the ultraviolet-curable resin to the one surface of the inner layer substrate again, and curing the applied surface again with ultraviolet light; and ultraviolet-curing the other surface of the inner layer substrate. Apply resin,
A step of curing the application surface with ultraviolet light, a step of removing moisture absorption of the ultraviolet curable resin by baking treatment of the inner layer substrate, and a step of leveling the surface of the ultraviolet curable resin by leveling, an adhesive resin on the inner layer substrate. The method according to claim 2, further comprising: a step of heating and pressing the attached copper foil with a roll laminator; and a step of thermally curing the copper foil with the adhesive resin to form a copper-clad laminate with an inner layer circuit. Of manufacturing a multilayer printed wiring board. 4. The multilayer according to claim 3, wherein the surface of the copper foil of the copper-clad laminate is immersed in a mixture of sodium chlorite and caustic soda to be subjected to needle crystallization. Manufacturing method of printed wiring board. 5. A step of etching the entire surface of the surface copper foil of the copper-clad laminate containing the inner layer circuit, and a step of forming a laser hole by irradiating the ultraviolet curable resin with a carbon dioxide laser or an excimer laser. Forming a laser via hole by applying copper panel plating to the laser hole,
The method of manufacturing a multilayer printed wiring board according to claim 3, further comprising a step of forming an outermost layer pattern by etching an outermost layer of the inner substrate. 6. An application condition under which the ultraviolet-curable resin penetrates into the via hole by a capillary phenomenon, and
The method for producing a multilayer printed wiring board according to any one of claims 2 to 5, wherein the method has a resin viscosity suitable for this. 7. The method according to claim 2, wherein the ultraviolet curable resin is applied only around the via hole.
The method for producing a multilayer printed wiring board according to any one of the above. 8. The method according to claim 1, wherein said via hole is a through-hole.