JPH08222835A - Manufacture of printed wiring board - Google Patents

Abstract

PURPOSE: To obtain large adhesive strength between an insulating layer and conductor layer by exposing part of copper particles on the surface of the insulating layer by removing the surface layer of the insulating layer after fixing the particles scattered on the surface of the insulating layer by pressing down the particles and forming a conductor circuit by plating the surface of the insulating layer on which part of the particles is exposed. CONSTITUTION: A conductor circuit 2a is formed by etching the copper which is the base material for a copper-plated laminated substrate 1 and an insulating layer 3 is formed on the surface of the substrate 1. Then copper particles 4 are spread on the surface of the layer 3 and buried in the layer 3 by pressing down the particles 4 and part of the particles 4 is exposed on the surface of the layer 3 by polishing the surface of the layer 3. In addition, a second conductor circuit 6a is formed by forming via holes 5 and plated conductor layers on the surface of the layer 3 and internal surfaces of the holes 5, and then, etching the conductor layer in a second pattern. Moreover, a third conductor circuit 9a is formed by opening a through hole 8 and forming a plated conductor layer on the internal surface of the hole 8 and the surface of an insulating layer 7, and then, etching the conductor layer 7 in a third pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a method for manufacturing a printed wiring board in which a conductive layer is formed on an insulating layer by plating or the like.

[0002]

2. Description of the Related Art As electronic devices are becoming more portable, the demand for multilayered and high-density printed wiring boards is ever increasing. As a method of manufacturing a printed wiring board that meets such a demand, a build-up method in which a conductor layer and an insulating layer are repeatedly formed on a substrate to form a multilayer has attracted attention. By applying the build-up method, it is possible to manufacture an inexpensive and high-density printed wiring board. However, in the build-up method, there is a problem with the adhesion strength between the insulating layer and the conductor layer that are repeatedly formed, and various measures have been taken to improve the adhesion strength. Here, JP-A-3-28
The method of spraying copper powder on the interface between the insulating layer and the conductor layer reported in Japanese Patent No. 3493 will be described with reference to FIG. 9 as a conventional technique.

First, a base material 10 made of a copper-clad glass epoxy laminated substrate as shown in FIG. 9A is used as a starting material.
As shown in FIG. 9B, a base material copper 11 is provided on the base material 10, and the base material copper 11 is etched into a desired pattern shape by an ordinary photolithography method or the like to form a circuit composed of the base material copper 11 ( Hereinafter, simply referred to as the conductor circuit 11a) is formed.

Next, as shown in FIG. 9C, an insulating layer 12 is formed on the surface of the base material 10 on which the conductor circuit 11a is formed. Further, as shown in FIG. 9D, copper powder 13 is evenly dispersed on the surface of the uncured insulating layer 12 without any gap, and the insulating layer 12 is cured by heating. Next, as shown in FIG. 9E, the insulating layer 12 is similarly formed on the back surface of the base material 10,
Copper powder 13 is sprinkled to cure the insulating layer 12. Next, as shown in FIG. 9F, copper plating is performed on the copper powder 13 that has been uniformly dispersed to form a conductor layer 14. Furthermore, FIG.
As shown in (a), the conductor layer 14 is etched into a desired pattern shape by a photolithography method or the like to form a circuit including the conductor layer 14 (hereinafter, simply referred to as a conductor circuit 14a).

By repeating the above steps, a structure in which a plurality of conductor layers and an insulating layer overlap each other as shown in FIG. 10B is obtained. Next, as shown in FIG.
Through holes 16 are formed to vertically penetrate the substrate 10 using a drill. Next, as shown in FIG.
After laminating the insulating layer 15 and the layer of the copper powder 13, copper plating is performed on the surface of the layer of the copper powder 13 and the inner peripheral surface of the through-hole 16 to form the conductor layer 17. Further, as shown in FIG. 11B, the conductor layer 17 is etched by a photolithography method or the like, and the upper and lower sides of the base material 10 and the through-holes 1 are etched.
A conductor circuit 17a composed of the conductor layer 17 is formed on the inner peripheral surface of 6 to obtain a multilayer printed wiring board.

[0006]

The above-mentioned prior art has the following drawbacks. That is, (1) the copper powder 13 dispersed by the conventional technique is shown in FIG.
As shown in (b), only the lower part is inserted into the insulating layers 12 and 15, and most of them are exposed on the surface of the insulating layer. Therefore, the adhesion area between the insulating layers 12 and 15 and the copper powder 13 is small, and the chemical solution easily penetrates into the interface between the insulating layers 12 to 15 and the copper powder 13 due to the capillary phenomenon. Usually, a series of treatments for electroless copper plating include micro-etching treatment for cleaning the copper surface, but the etching solution enters between the insulating layers 12 and 15 and the copper powder 13 to dissolve the copper powder 13. . Therefore, the copper powder 13 is easily removed from the insulating layers 12 and 15, and the expected density strength cannot be obtained.
The copper powder 13 may contaminate the bath of the electroless copper plating line. (2) As a means for improving the wiring density, it is effective to introduce via holes that connect only the adjacent upper and lower conductor circuits. However, in the method for manufacturing a printed wiring board according to the conventional technique,
It is difficult to form a via hole. That is, as the via hole, there are one in which an insulating layer is formed of a photo-curing resin and a via hole is formed by a photolithography method, and another in which an insulating layer is formed of a thermosetting resin and a via hole is formed by a laser. And copper powder 13 on the insulating layers 12 and 15
In the method of spraying without gaps, the ultraviolet or laser light used for photocuring is blocked by the layer of the copper powder 13 and the insulating layer 1
Since it does not reach 2,15, it is difficult to form a via hole.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a method of manufacturing a printed wiring board which improves the adhesion strength between an insulating layer and a conductor layer, which has been a problem in the past. .

[0008]

In order to achieve the above object, a method of manufacturing a printed wiring board according to the present invention comprises an insulating layer forming step, a copper powder spraying step, an embedding step, and a copper powder exposing step. A method for manufacturing a printed wiring board including at least a conductor circuit forming step, wherein the insulating layer forming step forms an insulating layer on the surface of the conductor circuit formed on the substrate, and the copper powder spraying step is The copper powder is sprayed on the insulating layer, and the embedding step is for pressing down the copper powder into the insulating layer and fixing the copper powder in the insulating layer. Is to remove the surface layer of the insulating layer to expose a part of the copper powder on the surface of the insulating layer, and the conductor circuit forming step performs plating on the surface of the insulating layer where the copper powder is partially exposed. A conductor circuit is formed.

Further, at least an insulating layer forming step, a copper powder spraying step, a burying step, a copper powder exposing step, a via hole forming step, and a conductor circuit forming step are included, and conductors adjacent to each other with an insulating layer sandwiched therebetween are included. A method for manufacturing a printed wiring board in which circuits are electrically connected via via holes, wherein an insulating layer forming step forms an insulating layer on a surface of a conductor circuit formed on a substrate. The spraying step is one in which copper powder is scattered on the insulating layer, and the embedding step is to push down the copper powder into the insulating layer to fix the copper powder in the insulating layer. The copper powder exposing step removes the surface layer of the insulating layer to expose a part of the copper powder on the surface of the insulating layer, and the via hole forming step forms a via hole penetrating the insulating layer, Conductor circuit formation process is a part of the copper powder On the surface and the inner surface of the via hole of the exposed insulating layer is to form a conductor circuit performs plating.

In the insulating layer forming step, the surface of the conductor circuit formed on the substrate is roughened to increase the adhesion strength between the insulating layer and the conductor circuit.

In the copper powder exposing step, the surface layer of the insulating layer is polished to expose the copper powder on the surface of the insulating layer.

Further, in the copper powder exposing step, the surface layer of the insulating layer is chemically oxidized to expose the copper powder to the surface of the insulating layer.

Further, in the conductor circuit forming step, a conductor layer forming a conductor circuit formed on the surface of the insulating layer by plating is brought into close contact with the insulating layer by copper powder embedded in the insulating layer.

In the copper powder spraying step, copper powder is sprayed on the surface of the insulating layer whose surface layer is at least uncured.

Further, in the copper powder spraying step, copper powder is sprayed on the insulating layer at intervals such that a light beam for forming a via hole reaches the insulating layer.

In the embedding step, copper powder is pressed down and fixed in the insulating layer when at least the surface layer of the insulating layer is in an uncured state.

[0017]

[Function] The copper powder scattered on the insulating layer is pressed down so that the copper powder is completely embedded and fixed in the insulating layer to improve the anchoring effect of the copper powder on the insulating layer. , Improving the adhesion strength of the plated coating forming the conductor layer to the insulating layer.

Further, by completely embedding and fixing the copper powder in the insulating layer, it becomes possible to sufficiently secure the adhesion strength of the plated coating forming the conductor layer to the insulating layer, so that the amount of the copper powder sprayed can be increased. By controlling, it becomes possible to form a via hole in the insulating layer in which the copper powder is buried.

[0019]

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

(Embodiment 1) FIGS. 1 to 4 are sectional views showing a method of manufacturing a printed wiring board according to Embodiment 1 of the present invention in the order of steps.

In the figure, the method for manufacturing a printed wiring board according to the present invention basically comprises an insulating layer forming step, a copper powder spraying step, an embedding step, a copper powder exposing step, and a conductor circuit forming step. In the insulating layer forming step, an insulating layer is formed on the surface of the conductor circuit formed on the substrate, and in the copper powder dispersing step, copper powder is dispersed on the insulating layer, and an embedding step is performed. In, in pressing the copper powder into the insulating layer and fixing the copper powder in the insulating layer, in the copper powder exposing step, the surface layer of the insulating layer is removed and a part of the copper powder is applied to the surface of the insulating layer. In the step of forming a conductor circuit by exposing, the conductor circuit is formed by plating on the surface of the insulating layer where a part of the copper powder is exposed in the conductor circuit forming step, and the copper powder embedded in the insulating layer forms an insulating layer of a plating film forming the conductor layer. Increase the adhesion strength to
It manufactures multi-layered and high-density printed wiring boards.

Furthermore, the method for manufacturing a printed wiring board according to the present invention has a via hole forming step in addition to the above-mentioned basic structure, and in the via hole forming step, a via hole penetrating the insulating layer is formed to form a conductor circuit. In the forming step, the surface of the insulating layer where a part of the copper powder is exposed and the inner surface of the via hole are plated to form a conductor circuit, and the conductor layer is sandwiched between the conductor circuits to conduct electricity through the via hole. The printed wiring board thus manufactured is manufactured.

Next, a method for manufacturing a printed wiring board according to the present invention will be described with reference to specific examples shown in FIGS. In this embodiment, as a substrate on which a conductor circuit is formed as shown in FIG. 1A, a base made of a copper-clad glass epoxy laminated substrate having a base material copper (copper foil) 2 forming a conductor layer adhered on both sides. Material 1 is used.

First, as shown in FIG. 1 (b), a base material copper 2 of a base material 1 is etched into a pattern of a desired shape by a normal photolithography method or the like to form a conductor circuit (hereinafter referred to as a conductor) composed of the base material copper 2. Circuit 2a). Base material copper 2 here
Using a dry film as a resist layer that serves as a mask when etching a pattern of a desired shape, copper (copper foil) as a base material
An aqueous solution of ferric chloride was used as an etching solution for etching 2.

Next, when forming the insulating layer 3 on the substrate 1, the surface of the conductor circuit 2a is roughened with an aqueous solution of acidic cupric chloride, and then the conductor circuit 2 is formed with an aqueous solution of alkaline potassium persulfate.
By oxidizing the surface of a and roughening it into a needle shape, the adhesion between the conductor circuit 2a and the insulating layer 3 to be formed next is improved. In addition to the alkaline potassium persulfate aqueous solution shown here, alkaline sodium chlorite, potassium sulfide-ammonia chloride aqueous solution or the like can be used for the rough surface treatment of the conductor circuit 2a.

As shown in FIG. 1C, after the conductor circuit 2a is roughened, a photosensitive liquid insulating resin is applied by a roll coater on the surface of the base material 1 on which the conductor circuit 2a is formed. The insulating layer 3 is formed by coating. To form the insulating layer 3,
Besides the roll coater, methods such as a curtain coater, a spray coater, and screen printing are used. With the roll coater, the insulating layer 3 having a thickness of 15 μm can be obtained by one coating, so the coating was repeated 4 times to obtain the insulating layer 3 having a thickness of 60 μm. Since the thickness of the resin layer 3 to be formed differs depending on the coating method, coating and drying are repeated several times to form the insulating layer 3 having a desired thickness. In addition, in order to leave only the surface layer of the insulating layer 3 in an undried state, after the third coating, pre-curing is performed by baking (90 ° C., 30 minutes), and after the fourth coating, Do not bake. As a result, the insulating layer 3 is a dried layer 45μ.
m and the undried layer 15 μm overlap each other.

Next, as shown in FIG. 1D, copper powder 4 having an average particle size of 10 μm and a particle size distribution of 5 to 15 μm is sprayed on the surface of the insulating layer 3 whose surface layer is undried. Here, in performing the via hole forming step in the subsequent step, the copper powder 4 is evenly dispersed at a density of about 2 mg / cm ² . For spraying copper powder, use a conveyor type air spraying device
It was carried out at a pressure of ˜0.8 kg / cm ² and a conveyor speed of 2 m / min. If the copper powder 4 is excessively dispersed, the photo-curing in the subsequent step is not sufficiently performed and the via hole cannot be formed. To form a via hole, it is necessary that the surface of the base material 1 where the via hole is formed is not covered with the copper powder 4 and an area of at least 50% or more is exposed. In this embodiment, about 60% of the surface area is exposed. Among the insulating layers 3, the layer coated for the fourth time has no fluidity, and therefore has fluidity, and therefore the scattered copper powder 4 is embedded in the insulating layer 3.

Next, as shown in FIG. 1 (e), copper powder 4 is embedded in the insulating layer 3 by pressing. The press uses a stainless steel end plate, and at room temperature 80 to 100 kg / c
The copper powder 4 is completely buried in the insulating layer 3 and three-dimensionally captured by fixing the copper powder 4 in the insulating layer 3 by performing the treatment at a pressure of m ² for 60 seconds. When performing the pressing process, a polyethylene peeling film is interposed between the end plate and the insulating layer 3 so that the end plate is not attached to the surface of the uncured insulating layer 3.
Further, as shown in FIG. 1F, the same process is performed on the back surface.

Before the process of exposing the copper powder 4 to the surface of the insulating layer 3 in the next step, baking (90 ° C., 30 minutes) is performed to pre-cure the uncured portion of the insulating layer 3.
Then, as shown in FIG. 2A, the surface layer of the insulating layer 3 is polished by about 5 μm by a belt polishing device. Here, # 60
No. 0 belt was used at a pressure of ² kgf / cm ² , and polishing was repeated 3 times. Since the copper powder 4 is distributed within about 5 μm from the surface of the insulating layer 3, most of the copper powder 4 is partially exposed on the surface of the insulating layer 3 by polishing.

Next, as shown in FIG. 2B, the surface of the insulating layer 3 other than the via hole forming portion is photo-cured by irradiation with ultraviolet rays (integrated exposure amount of 4000 to 6000 mJ), and further development is carried out. The insulating layer 3 and the copper powder 4 in the via-hole forming portion, which is hardened, are simultaneously removed to form a via hole 5 (via diameter of 0.1 mm or more).
The lower conductor circuit 2a is exposed inside. Insulation layer 3
Baking (140 ° C, 1 hour) to accelerate curing
I do.

Alkaline permanganate aqueous solution (KMn
O4: 40-60g / 1, Normality: 1.0-1.2N,
60 to 80 ° C.) is used to chemically oxidize the surface of the insulating layer 3. By oxidation, the surface layer 1 to 2 μm of the insulating layer 3 is removed, and the copper powder 4 not exposed by the polishing by the belt polishing device is partially exposed. At the same time, the surface of the insulating layer 3 is roughened to improve the adhesion between the insulating layer 3 and the conductor layer 6 to be formed next. Next, as shown in FIG. 2C, electroless copper plating and electrolytic copper plating are continuously performed to form a plating film on the exposed surface of the copper powder 4 on the insulating layer 3 and the inner surface of the via hole 5. A conductor layer 6 of 20 μm is formed.
The conductor layer 6 may be formed only by electroless copper plating. The copper powder 4 scattered by the present invention is completely embedded in the insulating layer 3 and is in a state as shown in FIG. The copper powder 4 and the conductor layer 6 also have good adhesion, and the anchor effect improves the adhesion of the conductor layer 6 to the insulating layer 3. In addition, since the copper powder 4 is completely embedded in the insulating layer 3, as shown in FIG.
No gap is formed between the copper powder 4 and the insulating layer 3 unlike the conventional case shown in (b), and the chemical liquid is less likely to permeate, and the copper powder 4 does not fall off even in the micro etching process. However, excessive micro-etching completely dissolves the copper powder 4 exposed on the surface of the insulating layer 3, so it is necessary to control the micro-etching to a thickness of about 0.5 to 1 μm.

Next, as shown in FIG. 2D, as shown in FIG.
The conductor layer 6 is etched into a pattern having a desired shape by the usual photolithography method used in step 1 to form a conductor circuit composed of the conductor layer 6 (hereinafter referred to as a conductor circuit 6a). In this case, a part of the conductor circuit 2 a on the base material 1 and a part of the conductor circuit 6 a on the insulating layer 3 are electrically connected by the conductor layer 6 formed on the inner surface of the via hole 5.

Further, the above-mentioned steps are repeated and shown in FIG.
A structure in which a plurality of conductor layers and an insulating layer are overlapped with each other is obtained.

Next, as shown in FIG. 3B, as shown in FIG.
The via hole 5 is formed in the same manner as in the step (1), and the through-hole 8 is opened by an N / C drill.

Next, as shown in FIG. 3 (c), plating is performed to provide a conductor layer 9 made of a plated film on the inner surface of the through hole 8 and the surface of the insulating layer 7. Of the conductor circuits 2a and 6a on the insulating layer 3 or 7, those exposed in the through holes 8 are conducted to the conductor layer 9. Finally, as shown in FIG. 4, the conductor layer 9 on the insulating layer 7 is etched into a pattern of a desired shape by the ordinary photolithography method used in FIG. The conductor circuit 9a) is formed.

(Embodiment 2) FIGS. 5 to 8 are sectional views showing Embodiment 2 of the present invention. Next, a method for manufacturing a printed wiring board according to the present invention will be described with reference to specific examples shown in FIGS. In this embodiment, as a substrate on which a conductor circuit is formed as shown in FIG. 5A, a base material copper (copper foil) forming a conductor layer.
2 is used as a base material 1 made of a copper-clad glass-epoxy laminated substrate having both surfaces attached.

First, as shown in FIG. 5B, the base material copper 2 of the base material 1 is etched into a pattern of a desired shape by a normal photolithography method or the like to form a conductor circuit (hereinafter referred to as a conductor) made of the base material copper 2. Circuit 2a). Base material copper 2 here
Using a dry film as a resist layer that serves as a mask when etching a pattern of a desired shape, copper (copper foil) as a base material
An aqueous solution of ferric chloride was used as an etching solution for etching 2.

Next, in forming the insulating layer 3 on the substrate 1, the surface of the conductor circuit 2a is roughened with an aqueous solution of acidic cupric chloride, and then the conductor circuit 2 is treated with an aqueous solution of alkaline potassium persulfate.
By oxidizing the surface of a and roughening it into a needle shape, the adhesion between the conductor circuit 2a and the insulating layer 3 to be formed next is improved. In addition to the alkaline potassium persulfate aqueous solution shown here, alkaline sodium chlorite, potassium sulfide-ammonia chloride aqueous solution or the like can be used for the rough surface treatment of the conductor circuit 2a.

As shown in FIG. 5C, after the conductor circuit 2a is roughened, a photosensitive liquid insulating resin is applied to the surface of the base material 1 on which the conductor circuit 2a is formed by a curtain coater. The insulating layer 3 is formed by coating. In addition to the curtain coater, a method such as a roll coater, a play coater, or screen printing is used to form the insulating layer 3. With the curtain coater, the insulating layer 3 having a thickness of 10 μm can be obtained by one application, so the application is repeated 5 times and 50 μm.
m insulating layer 3 was obtained. Since the thickness of the resin layer 3 to be formed differs depending on the coating method, coating and drying are repeated several times to form the insulating layer 3 having a desired thickness. Also, the insulating layer 3
In order to leave only the surface layer of No. 1 in an undried state, after the fourth coating, pre-curing is performed by baking (90 ° C., 30 minutes), and after the fifth coating, baking is not performed. As a result, the insulating layer 3 becomes the dried layer 4
0 μm and 10 μm of the undried layer overlap each other.

Next, as shown in FIG. 5D, copper powder 4 having an average particle size of 10 μm and a particle size distribution of 5 to 15 μm is sprayed on the surface of the insulating layer 3 whose surface layer is undried. When performing the via hole forming step in the subsequent step, the copper powder 4
Is evenly distributed at a density of about 2 mg / cm ² . For spraying copper powder, use a conveyor type air spraying device,
It was carried out at a pressure of 0.8 kg / cm ² and a conveyor speed of 2 m / min. If the copper powder 4 is excessively dispersed, the photo-curing in the subsequent step is not sufficiently performed and the via hole cannot be formed. To form a via hole, it is necessary that the surface of the base material 1 where the via hole is formed is not covered with the copper powder 4 and an area of at least 50% or more is exposed. In this embodiment, about 60% of the surface area is exposed. Of the insulating layers 3, the layer coated for the fourth time has no fluidity, and therefore has fluidity, and therefore, the scattered copper powder is embedded in the surface layer of the insulating layer 3.

Next, as shown in FIG. 5E, the copper powder 4 is embedded in the insulating layer 3 by a roller treatment. The roller treatment is performed by using a stainless steel roller whose peripheral surface is coated with polyethylene. When the roller treatment is performed, the peripheral surface of the roller is not attached to the surface of the uncured insulating layer 3. The linear pressure for pressing down the copper powder 4 by the roller is 100 to 120 kg / cm ² , the relative transport speed between the roller and the substrate 1 is 1 m / min, and the copper powder 4 is completely embedded in the insulating layer 3 to form a three-dimensional structure. And then the copper powder 4 is fixed in the insulating layer 3. Further, as shown in FIG. 5F, the same process is performed on the back surface.

Before the process of exposing the copper powder 4 to the surface of the insulating layer 3 in the next step, baking (90 ° C., 30 minutes) is performed to pre-cure the uncured portion of the insulating layer 3.

Next, as shown in FIG. 6 (a), the surface of the insulating layer 3 other than the via hole forming portion is photo-cured by irradiating with ultraviolet rays (integrated exposure amount 4000-6000 mJ), and further developed to develop the surface. The insulating layer 3 and the copper powder 4 in the via-hole forming portion, which is hardened, are simultaneously removed to form a via hole 5 (via diameter of 0.1 mm or more).
The lower conductor circuit 2a is exposed inside. Insulation layer 3
Baking (140 ° C, 1 hour) to accelerate curing
I do.

Next, as shown in FIG. 6 (b), an aqueous alkaline permanganate solution (KMnO4: 40-60 g / 1,
Normality: 1.0 to 1.2 N, 60 to 80 ° C.)
The surface of the insulating layer 3 is chemically oxidized. By oxidation, the surface layer 1 to 2 μm of the insulating layer 3 is removed. Since the copper powder 4 is distributed within about 1 μm from the surface of the insulating layer 3, almost all the copper powder 4 is partially exposed on the surface of the insulating layer 3 by the chemical oxidation treatment. Since the embedding of the copper powder 4 is shallow, belt polishing as in Example 1 is not necessary. Since the insulating layer 3 is not mechanically polished, stress is not applied to the copper powder 4, and the copper powder 4 is less likely to fall off. At the same time, the surface of the insulating layer 3 is roughened to improve the adhesion between the insulating layer 3 and the conductor layer 6 to be formed next. Next, as shown in FIG. 6C, electroless copper plating and electrolytic copper plating are continuously performed to expose the surface of the insulating layer 3 where the copper powder 4 is exposed and the via hole 5.
A conductor layer 6 having a thickness of 20 μm and formed of a plating film is formed on the inner surface of the. The conductor layer 6 may be formed only by electroless copper plating. The copper powder 4 scattered by the present invention is completely embedded in the insulating layer 3 and is in a state as shown in FIG.
The copper powder 4 and the conductor layer 6 also have good adhesion, and the adhesion effect improves the adhesion between the insulating layer 3 and the conductor layer 6. In addition, since the copper powder 4 is completely embedded in the insulating layer 3, as shown in FIG.
No gap is formed between the copper powder 4 and the insulating layer 3 unlike the conventional case shown in (b), and the chemical liquid is less likely to permeate, and the copper powder 4 does not fall off even in the micro etching process. However, excessive micro-etching completely dissolves the copper powder 4 exposed on the surface of the insulating layer 3, so it is necessary to control the micro-etching to a thickness of about 0.5 to 1 μm.

Next, as shown in FIG. 6D, as shown in FIG.
The conductor layer 6 is etched into a pattern having a desired shape by the usual photolithography method used in step 1 to form a conductor circuit composed of the conductor layer 6 (hereinafter referred to as a conductor circuit 6a). In this case, a part of the conductor circuit 2 a on the base material 1 and a part of the conductor circuit 6 a on the insulating layer 3 are electrically connected by the conductor layer 6 formed on the inner surface of the via hole 5.

Further, the steps described above are repeated, and FIG.
A structure in which a plurality of conductor layers and an insulating layer are overlapped with each other is obtained.

Next, as shown in FIG. 7B, as shown in FIG.
The via hole 5 is formed in the same manner as in the step (1), and the through-hole 8 is opened by an N / C drill.

Next, as shown in FIG. 7C, plating is performed to provide a conductor layer 9 made of a plated film on the inner surface of the through hole 8 and the surface of the insulating layer 7. Of the conductor circuits 2a and 6a on the insulating layer 3 or 7, those exposed in the through holes 8 are conducted to the conductor layer 9. Finally, as shown in FIG. 8, the conductor layer 9 on the insulating layer 7 is etched into a pattern of a desired shape by the ordinary photolithography method used in FIG. The conductor circuit 9a) is formed.

[0049]

As described above, according to the present invention, the copper powder scattered on the surface of the insulating layer is three-dimensionally captured by the insulating layer, and extremely strong adhesion strength with the plated coating which is the conductor layer can be obtained. Further, since a strong adhesion strength can be secured, it is possible to form a via hole by controlling the amount of copper powder sprayed. As described above, according to the present invention, a high-density printed wiring board having excellent adhesion can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention in process order.

FIG. 2 is a cross-sectional view showing the first embodiment of the present invention in the order of steps.

FIG. 3 is a cross-sectional view showing the first embodiment of the present invention in the order of steps.

FIG. 4 is a cross-sectional view showing the first embodiment of the present invention in the order of steps.

5A to 5C are cross-sectional views showing the first embodiment of the present invention in the order of steps.

FIG. 6 is a cross-sectional view showing a second embodiment of the present invention in process order.

FIG. 7 is a cross-sectional view showing a second embodiment of the present invention in process order.

FIG. 8 is a cross-sectional view showing a second embodiment of the present invention in process order.

FIG. 9 is a cross-sectional view showing a conventional example in the order of steps.

FIG. 10 is a cross-sectional view showing a conventional example in the order of steps.

FIG. 11 is a cross-sectional view showing a conventional example in the order of steps.

FIG. 12 (a) is a cross-sectional view showing an embedded state of copper powder in the present invention, and FIG. 12 (b) is a cross-sectional view showing an embedded state of copper powder in a conventional example.

[Explanation of symbols]

 1 Base Material 2 Base Material Copper 2a Conductor Circuit 3 Insulating Layer 4 Copper Powder 5 Via Hole 6 Conductor Layer 6a Conductor Circuit 7 Insulating Layer 8 Through Through Hole 9 Conductor Layer 9a Conductor Circuit 10 Base Material 11 Base Material Copper 12 Insulation Layer 13 Copper Powder 14 Conductor Layer 15 Insulating Layer 16 Through Through Hole 17 Conductor Layer

Claims (9)

[Claims] 1. A method for manufacturing a printed wiring board, comprising at least an insulating layer forming step, a copper powder spraying step, an embedding step, a copper powder exposing step, and a conductor circuit forming step, the insulating layer forming step. Is for forming an insulating layer on the surface of the conductor circuit formed on the substrate, the copper powder spraying step is for spraying copper powder on the insulating layer, and the embedding step is for the copper powder. Is pressed down into the insulating layer to fix the copper powder in the insulating layer. In the copper powder exposing step, the surface layer of the insulating layer is removed to expose a part of the copper powder on the surface of the insulating layer. The method for producing a printed wiring board is characterized in that in the conductor circuit forming step, a conductor circuit is formed by plating the surface of the insulating layer where a part of the copper powder is exposed. 2. An insulating layer forming step, a copper powder spraying step, a burying step, a copper powder exposing step, a via hole forming step, and a conductor circuit forming step, which at least include an insulating layer sandwiched between adjacent conductors. A method for manufacturing a printed wiring board in which circuits are electrically connected via via holes, wherein the insulating layer forming step forms an insulating layer on the surface of a conductor circuit formed on a substrate. The spraying step is one in which copper powder is scattered on the insulating layer, and the embedding step is for pressing down the copper powder into the insulating layer to fix the copper powder in the insulating layer, The copper powder exposing step removes the surface layer of the insulating layer to expose a part of the copper powder on the surface of the insulating layer, and the via hole forming step forms a via hole penetrating the insulating layer, In the conductor circuit forming step, part of the copper powder is A method for manufacturing a printed wiring board, characterized in that a conductor circuit is formed by plating the exposed surface of the insulating layer and the inner surface of the via hole. 3. The insulating layer forming step is to roughen the surface of a conductor circuit formed on a substrate to enhance the adhesion strength between the insulating layer and the conductor circuit.
Or the method for manufacturing a printed wiring board according to item 2. 4. The printed wiring board according to claim 1, wherein in the copper powder exposing step, the surface layer of the insulating layer is polished to expose the copper powder to the surface of the insulating layer. Production method. 5. The printing according to claim 1, wherein the copper powder exposing step is a step of chemically oxidizing the surface layer of the insulating layer to expose the copper powder on the surface of the insulating layer. Wiring board manufacturing method. 6. The conductor circuit forming step comprises contacting a conductor layer forming a conductor circuit formed by plating on the surface of the insulating layer with the copper powder embedded in the insulating layer onto the insulating layer. The method for manufacturing a printed wiring board according to claim 1, wherein the printed wiring board is manufactured. 7. The production of a printed wiring board according to claim 1, wherein in the copper powder spraying step, copper powder is sprayed on the surface of the insulating layer in which at least the surface layer is uncured. Method. 8. The printing according to claim 2, wherein in the copper powder spraying step, copper powder is sprayed on the insulating layer at intervals such that a light beam for forming a via hole reaches the insulating layer. Wiring board manufacturing method. 9. The embedding step is characterized in that, at least when the surface layer of the insulating layer is in an uncured state, the copper powder is pressed down and fixed in the insulating layer.
A method for manufacturing a printed wiring board according to.