JP2002185132A - Dry film for multilayer printed circuit board, method for manufacturing multilayer printed circuit board using the same, and the multilayer printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the adhesion between a conductive circuit and an insulation resin layer of a multiplayer printed circuit board in which the conductive circuit is formed by soldering, and to prevent shortcircuit among circuits for higher reliability. SOLUTION: This dry film for multiplayer printed circuit board is provided with an insulation resin layer 3 which is made of dry substance of photoresist and/or thermosetting resin compound and is laminated on an irregular surface of a first protection film 1 in which an irregular surface 2, where the center line roughness of the irregular part (Ra) is 1 μm<=Ra<=5 μm, the count (n) of irregular average height (Rc) of a roughness curve at the surface length of 2.5 mm is 200 or more at 1 μm<=Rc<=10 μm and 2000 or more at 0.1 μm<=Rc<=1 μm, is formed on one surface. The dry film is thermally press-fitted onto a substrate 5 in which a conductive circuit 6 is formed in a manner that the insulation resin layer may be adhered. Next, fixation of shape of the irregular surface of the transferred insulation resin layer, peeling of the first protection film 1, formation of a via hole, covering of a plating layer 8, and formation of a conductor circuit are performed in sequence.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry film for a multilayer printed wiring board, and more particularly to an electronic device, a computer,
The present invention relates to a dry film for a multilayer printed wiring board used in a communication device, a method for manufacturing a multilayer printed wiring board using the same, and a multilayer printed wiring board obtained by the method.

[0002]

2. Description of the Related Art A conventional method for manufacturing a multilayer printed wiring board in which a conductive circuit is additionally formed by plating on an insulating layer will be described with reference to the accompanying drawings. As shown in a), a conductor circuit 6 is formed on a substrate 5. Next, as shown in FIG.
On the substrate 5 on which the conductive circuit 6 is formed, as an insulating layer, an insulating resin layer 9 containing fine powder containing fine powder particles soluble in acid.
Is formed and cured. Next, as shown in FIG. 5 (c), the fine powder particles on the surface are removed by an acid treatment, and a concave portion 10 is formed on the surface of the insulating resin layer 9 containing the fine powder to form an uneven surface.
The adhesiveness with a plating layer to be formed later is improved. Next, as shown in FIG. 5D, chemical plating is performed to form a plating layer 8. In general, calcium carbonate is used as the fine powder soluble in the above-mentioned acids (Japanese Patent Application Laid-Open No. 2-252293 and Japanese Patent Application Laid-Open No. 57-11108).
Reference).

On the other hand, FIG. 6 shows another method. First, as shown in FIG. 6 (a), a heat-resistant material which becomes hardly soluble in a chromic acid aqueous solution by a curing treatment is placed on a substrate 5 on which a conductor circuit 6 is formed. A liquid epoxy resin liquid is applied to form a liquid insulating resin layer 12. Next, as shown in FIG. 6B, an epoxy resin powder 13 that is hardly soluble in the heat-resistant epoxy resin liquid and soluble in the chromic acid aqueous solution is sprayed on the liquid insulating resin layer 12 by compressed air. Next, as shown in FIG.
Is allowed to stand, so that the epoxy resin powder 13 sprayed on the insulating resin layer 12 floats on the surface due to the relationship between the specific gravity of the two and the surface tension of the liquid. Next, in this state, the insulating resin layer 12 is heated and dried to be cured, and then the surface is roughened with a chromic acid aqueous solution and, at the same time, the epoxy resin powder 13 is dissolved, as shown in FIG. A large number of concave portions 10 are formed on the surface of the insulating resin layer 12 thus formed. Next, FIG.
As shown in (e), a plating layer 8 is formed on the surface by chemical plating (see JP-A-4-212496).

[0004]

In the conventional method using the insulating resin layer containing fine powder as described above, when an agglomerated portion of fine powder soluble in acid is formed, as shown in FIG. In the case where a pinhole 11 is generated after the acid treatment and a conductive circuit is formed by the plating layer 8 in this state, FIG.
As shown in (d), there is a problem in the insulation property that the conductor circuit formed by the plating layer 8 conducts with the underlying conductor circuit 6 and is short-circuited. On the other hand, in a method in which an epoxy resin powder 13 is sprayed on a liquid insulating resin layer 12 made of a heat-resistant epoxy resin liquid, and the epoxy resin powder is floated on a surface portion due to the relationship between the specific gravity of the two and the surface tension of the liquid, A similar problem occurs when layer 12 is thin.

Accordingly, an object of the present invention is to provide good adhesion between an insulating resin layer and a conductor circuit formed by plating on the insulating resin layer,
The purpose of the present invention is to provide a dry film that can be suitably used for manufacturing a highly reliable multilayer printed wiring board without a short circuit between conductor circuits, and further, by using such a dry film, high quality and high reliability. It is an object of the present invention to provide a method capable of manufacturing a multilayer printed wiring board and shortening the manufacturing process as compared with the conventional method, and a high quality and highly reliable multilayer printed wiring board obtained by the method.

[0006]

According to a first aspect of the present invention, there is provided, on one surface, a center line average roughness (Ra) of an uneven portion of 1 μm ≦ Ra ≦ 5 μm. And the count value (n) of the average height (Rc) of the unevenness of the roughness curve at a length of 2.5 mm on the surface is 1 μm
≦ Rc ≦ 200 μm or more at 10 μm, 0.1 μm ≦
A first protective film on which at least 2000 uneven surfaces are formed when Rc ≦ 1 μm, and drying of a photocurable and / or thermosetting resin composition laminated on the uneven surface of the first protective film; A dry film for a multilayer printed wiring board, comprising: an insulating resin layer made of a product; and a second protective film laminated on the resin insulating layer.

Here, the center line average roughness (Ra) is J
A part of the measured length (L) is extracted from the roughness curve in the direction of the center line thereof, and the center line of the extracted part is defined as the X axis, and the ordinate direction is defined as the Y axis.
When the roughness curve is represented by y = f (x), the value obtained by the following equation (1) is expressed in micrometers (μ).
m).

(Equation 1)

Further, the average height (Rc) of the unevenness of the roughness curve
And it is intended to be defined by JIS B0660, the summit height of the roughness curve absolute value of (distance from the center line) (y _p)
And the average value of the absolute value (y _v ) of the depth (distance from the center line) of the valley bottom of the roughness curve, and the value obtained by the following equation (2) is expressed in micrometers (μm). ).

(Equation 2) In the above equation (2), n is the number of each of the peaks and valleys of the roughness curve within the reference length (measured length), and is referred to as “the average height of the unevenness of the roughness curve” in this specification. (Rc) count value ”. The uneven surface of the first protective film can be extremely easily formed by a method of directly processing the protective film by a sand blast method or a method of processing a film by passing a film between a metal roll and a rubber roll processed by a sand blast method. Can be formed.

According to a second aspect of the present invention, there is also provided a method of manufacturing a multilayer printed wiring board, the first aspect of which includes peeling off a second protective film of the dry film for a multilayer printed wiring board. Taking and thermocompression bonding on the substrate on which the conductor circuit is formed, so that the surface of the insulating resin layer is in close contact with the substrate,
After the film having the resist pattern is brought into close contact with the first protective film surface and exposed, the first protective film is peeled off, and a step of forming a photo via hole by performing development, and a step of heating and curing the insulating resin layer, Forming a conductor circuit by coating the surface of the heat-cured insulating resin layer with a plating layer, and then etching according to a predetermined pattern.

In a second aspect of the method for manufacturing a multilayer printed wiring board according to the present invention, the second protective film of the dry film for a multilayer printed wiring board is peeled off, and the conductor is so formed that the surface of the insulating resin layer adheres. A step of thermocompression bonding on a circuit-formed substrate, a step of cooling or exposing the entire surface, and then peeling off the first protective film, and a step of heating or exposing the entire surface of the insulating resin layer to cure; Forming a via hole by selectively irradiating the insulating resin layer with a laser beam, and coating the surface of the insulating resin layer with the via hole with a plating layer and then etching according to a predetermined pattern to form a conductor circuit And the step of performing

Further, in a third aspect of the method for manufacturing a multilayer printed wiring board according to the present invention, the second protective film of the dry film for a multilayer printed wiring board is peeled off so that the surface of the insulating resin layer adheres. A step of thermocompression bonding on a substrate on which a conductive circuit is formed, a step of heating or curing the insulating resin layer by exposing the entire surface, and a step of peeling off the first protective film and applying a laser beam to the cured insulating resin layer. Forming a via hole by selectively irradiating, and covering the surface of the insulating resin layer on which the via hole is formed with a plating layer, and then etching according to a predetermined pattern to form a conductive circuit. Features.

In a fourth aspect of the method for manufacturing a multilayer printed wiring board according to the present invention, the second protective film of the dry film for a multilayer printed wiring board is peeled off so that the surface of the insulating resin layer adheres. A step of thermocompression bonding on a substrate on which a conductive circuit is formed, a step of peeling off the first protective film, and a step of heat-curing the insulating resin layer; and selectively irradiating the heat-cured insulating resin layer with laser light. The method is characterized by including a step of forming a via hole and a step of forming a conductive circuit by coating a plating layer on the surface of the insulating resin layer in which the via hole is formed and then etching it according to a predetermined pattern.

Still further, according to a third aspect of the present invention, there is provided a multilayer printed wiring board having a conductive circuit formed on a wiring board via an insulating resin layer by the method as described above. At least the surface of the layer opposite to the wiring substrate has a center line average roughness (Ra) of 1 μm ≦
Ra ≦ 5 μm, and the count value (n) of the average height (Rc) of the unevenness of the roughness curve at a length of 2.5 mm on the surface is 200 or more at 0.1 μm ≦ Rc ≦ 10 μm, and 0.1 μm ≦ There is also provided a multilayer printed wiring board characterized in that 2000 or more uneven surfaces are formed when Rc ≦ 1 μm, and a conductor circuit is laminated on the uneven surface.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the method for manufacturing a multilayer printed wiring board according to the present invention, the center line average roughness (Ra) of one of the surfaces is 1 μm ≦ Ra ≦ 5 μm, and 2. The count value (n) of the average height (Rc) of the unevenness of the roughness curve at a length of 5 mm is 1 μm ≦ Rc ≦ 1
200 or more at 0 μm, 0.1 μm ≦ Rc ≦ 1 μm
a first protective film in which at least 2,000 uneven surfaces are formed at m, and a dried photo-curable and / or thermosetting resin composition laminated on the uneven surface of the first protective film. A dry film for a multilayer printed wiring board, comprising: an insulating resin layer formed on the substrate; and a second protective film laminated on the resin insulating layer. The surface of the insulating resin layer in contact with the uneven surface of the first protective film of the dry film is an uneven surface that faithfully transfers the uneven surface of the first protective film.

That is, the first protective film is not made by roughening the insulating resin layer itself as in the prior art, but by forming one surface of the first protective film in advance as an uneven surface by sandblasting or the like. Apply a photo-curable and / or thermosetting resin composition to the uneven surface of the film.
By drying, the uneven surface can be provided very easily, and the conventional roughening treatment can be omitted in the stage of manufacturing the multilayer printed wiring board. If the surface of the second protective film that is in contact with the insulating resin layer is also formed with an uneven surface by sandblasting or the like, both surfaces of the insulating resin layer become uneven, and are thermocompression-bonded to the substrate on which the conductive circuit is formed. In this case, the followability to the bottom of the corner of the conductor circuit is further improved, so that it is possible to perform pressure bonding with good adhesion without generating air pockets.

When the dry film is used, the second protective film is peeled off, and is thermocompression-bonded onto a substrate on which a conductive circuit is formed so that the surface of the insulating resin layer is in close contact. At this stage, the insulating resin layer is in a high temperature state,
If the first protective film is peeled off, the irregularities of the insulating resin layer transferred from the uneven surface may be destroyed. Therefore, it is necessary to fix the transferred uneven surface (fix the unevenness of the insulating resin layer surface). Depending on the material of the insulating resin layer to be used, there are the following fixing methods such as curing by selective pattern exposure or curing by overall exposure, heat curing, or cooling.

The first aspect of the present invention is a method using a photocurable and thermosetting resin composition as a material for an insulating resin layer, wherein a film having a resist pattern is brought into close contact with the first protective film surface. Exposure, thereby fixing the uneven surface transferred to the surface of the insulating resin layer at the exposed portion. The first protective film needs to be light-transmitting so that exposure can be performed. However, since the exposed surface is a flat surface, the film can be brought into close contact with the first protective film, and high-precision exposure can be performed. Thereafter, the first protective film is peeled off, development is performed to form a photo via hole, and the insulating resin layer is cured by heating. Since the surface of the insulating resin layer in this state is an uneven surface transferred from the uneven surface of the first protective film, the uneven surface acts as an anchor portion and adheres to the plating layer coated on the surface. The properties are significantly improved. In addition, since the soluble fine particles are not dissolved and removed from the surface by the surface roughening treatment as in the related art, a short circuit between the conductor circuits can be prevented without generating a pinhole. Furthermore, photovia holes can be relatively easily formed with high precision by exposure and development.

Further, according to the second aspect, after the insulating resin layer is thermocompression-bonded to the substrate as described above, it is cooled, preferably cooled to room temperature, or is exposed to the entire surface. The uneven surface transferred to the resin layer surface is fixed.
Thereafter, the first protective film is peeled off, and then the insulating resin layer is cured by heating or by exposing the entire surface. on the other hand,
In the third embodiment, the first protective film is peeled off after the insulating resin layer is heated or entirely exposed and cured to fix the uneven surface transferred to the insulating resin layer surface. The second aspect can be applied when a thermosetting resin composition, a photocurable resin composition or a photocurable / thermosetting resin composition is used as the material of the insulating resin layer, while the third aspect is applicable. Is applicable when a thermosetting resin composition or a photocurable resin composition is used. On the other hand, the fourth aspect is a method applicable when a thermosetting resin composition is used as a material of the insulating resin layer, and the insulating resin layer is thermocompressed on the substrate as described above. Since the uneven surface transferred to the surface is fixed,
Subsequently, after the first protective film is peeled off, the insulating resin layer is cured by heating. In the second to fourth aspects, via holes are formed by direct writing by selective irradiation of laser light thereafter. Since the surface of the insulating resin layer in this state also has an uneven surface transferred from the uneven surface of the first protective film, similarly to the above-described first embodiment, it has the same operation and effect.

Therefore, in any of the above-mentioned embodiments, a high-quality, high-reliability multilayer is formed by forming a plating layer and then etching according to a predetermined pattern to form a conductor circuit in accordance with a conventional method. Printed wiring boards can be manufactured.

[0020]

Next, embodiments of the present invention will be described with reference to the drawings. FIGS. 1A to 1C are partial cross-sectional views schematically showing the steps of manufacturing a dry film for a multilayer printed wiring board according to the present invention in the order of steps. First, as shown in FIG. 1 (a), on one surface of the first protective film 1, the center line average roughness (Ra) of the uneven portion is 1 μm ≦ Ra ≦ 5 μm, and the surface is 2.5 mm. The count value (n) of the average height (Rc) of the unevenness of the roughness curve at the length of 1 μm is 1 μm
200 or more, preferably 5 when ≦ Rc ≦ 10 μm
00 or more, 200 when 0.1 μm ≦ Rc ≦ 1 μm
Numerous irregularities are formed by sandblasting so as to have 0 or more, and preferably 2500 or more, to form the irregular surface 2.

The first protective film 1 has a photo-curing property and / or
Alternatively, it supports the insulating resin layer 3 obtained by applying the thermosetting resin composition, and needs to have appropriate flexibility. Generally, a polyethylene terephthalate (PET) film having a thickness of 10 to 200 μm is used. In addition, a synthetic resin film such as polyethylene, polypropylene, polycarbonate, and polyvinyl chloride is preferably used. The minute unevenness of the uneven surface 2 is necessary for providing unevenness to the insulating resin layer 3 as described later, and within the above range, the bonding area between the uneven surface transferred to the insulating resin layer 3 and the plating layer 8 Is greatly increased, whereby a high adhesive strength with the plating layer 8 is obtained.

The uneven surface 2 of the first protective film 1
Is that the center line average roughness (Ra) of the uneven portion is 1 μm> R
If a> a, a sufficient anchor effect cannot be obtained, and the adhesive strength between the uneven surface transferred to the insulating resin layer 3 and the plating layer 8 decreases, while if Ra> 5 μm, the plating layer formed on the upper surface 8 cannot be finely processed into a thin film wiring conductor. Therefore, the first protective film 1 transferred to the insulating resin layer 3
The uneven surface 2 (accordingly, the uneven surface of the transferred insulating resin layer 3) has a center line average roughness (Ra) of 1 μm.
It is necessary to satisfy the range of ≦ Ra ≦ 5 μm.

The uneven surface 2 of the first protective film 1 transferred to the insulating resin layer 3 has a count value of the average height (Rc) of the unevenness of the roughness curve at a length of 2.5 mm on the surface. (N) is 200 when 1 μm ≦ Rc ≦ 10 μm
If the number is less than 2,000 and less than 2,000 in 0.1 μm ≦ Rc ≦ 1 μm, the adhesive strength between the uneven surface transferred to the insulating resin layer and the plating layer 8 is reduced. Therefore, the uneven surface 2 of the first protective film 1 transferred to the insulating resin layer 3 (accordingly, the transferred uneven surface of the insulating resin layer 3) has a roughness curve of 2.5 mm on the surface. The count value (n) of the average height (Rc) of the unevenness is 1 μm ≦ Rc ≦ 10 μ
It is necessary to set the range to be 200 or more in m and 2000 or more in 0.1 μm ≦ Rc ≦ 1 μm.

The count value of the center line average roughness (Ra) of the uneven surface transferred to the insulating resin layer 3 and the average height (Rc) of the unevenness of the roughness curve at a length of 2.5 mm of the surface (Rc). n) shows the surface of the insulating resin layer 3 as an atomic force microscope (AF).
M: Scanned by Olympus Corporation, NV3000) at 50 μm, and each numerical value was obtained based on the result of measurement in AC (resonance) mode.

Next, as shown in FIG. 1 (b), a photocurable and / or thermosetting resin composition is uniformly applied onto the uneven surface 2 of the first protective film, and dried to form an insulating material. Resin layer 3
To form Examples of the coating method include an applicator, a bar coater, a roll coater, and a curtain flow coater, but are not limited to these methods. The dry film thickness is 10 to 100 depending on the thickness of the conductive circuit.
It is preferable to apply so that the thickness becomes μm.

Next, as shown in FIG. 1C, a second protective film 4 is laminated on the insulating resin layer 3 to form a dry film for a multilayer printed wiring board. The second protective film used here is for stably protecting the insulating resin layer 3 made of a dried product of the photocurable and / or thermosetting resin composition when the dry film is not used. Taken. Therefore, it is necessary to have an appropriate releasability that is difficult to peel off when the dry film is not used and that can be easily peeled off when used. As a material that satisfies such conditions, silicone is coated, in particular, baking-coated P having a thickness of 10 to 200 μm.
An ET film, a polyethylene film, a polypropylene film and the like are preferably used. This releasability is preferably applied to the first protective film 1 for the same reason.

In the photo-curable and / or thermosetting resin composition, as a developing type for forming a photo via hole, an alkali developing type light using a dilute alkaline aqueous solution as a developing solution in consideration of environmental problems. Curable and thermosetting resin compositions are preferred. As such a photocurable and thermosetting resin composition, for example, a carboxyl group-containing photosensitive resin obtained by adding an acid anhydride to a reaction product of a novolak type epoxy compound and an unsaturated monobasic acid is used. (See JP-A-61-243869), a carboxyl group-containing photosensitive resin obtained by reacting tetrahydrophthalic anhydride with a reaction product of a cresol novolak type epoxy resin, dimethylolpropionic acid and acrylic acid. (JP-A-6-3244)
No. 90), a composition using a carboxyl group-containing photosensitive resin obtained by reacting tetrahydrophthalic anhydride with a reaction product of a cresol novolac epoxy resin, acrylic acid and p-hydroxyphenethyl alcohol. 11-288091).

Examples of the photocurable and thermosetting resin composition which forms a via hole by selective irradiation with a laser beam include, for example, a composition comprising a mixture of an ultraviolet-curable monomer or oligomer and an epoxy resin (Japanese Patent Laid-Open No. 5-
186729), in addition to a composition containing a photocurable component and a thermosetting component, a composition containing a cationic polymerization catalyst and a resin having a cationically polymerizable group, an epoxy resin and an oxetane compound. There are things.

Further, as a thermosetting resin composition which forms a via hole by selective irradiation with a laser beam,
An epoxy resin composition or an oxetane compound-containing composition used for a thermosetting solder resist composition can be used. Furthermore, a composition obtained by blending a thermoplastic resin with the epoxy resin composition or the oxetane compound-containing composition used in the thermosetting solder resist composition can also be used.

Next, an example of a method for manufacturing a multilayer printed wiring board according to the first embodiment of the present invention will be described with reference to FIG. 2, but it is needless to say that the present invention is not limited to the following method. The dry film for a multilayer printed wiring board can be applied to various conventionally known methods for manufacturing a multilayer printed wiring board, depending on the material of the insulating resin layer to be used. First, a copper-clad laminate is etched to prepare a single-sided printed wiring board having a conductor circuit 6 formed on a substrate 5 as shown in FIG. Next, the second protective film 4 of the dry film for a multilayer printed wiring board shown in FIG. 1C is peeled off, and as shown in FIG. Thermocompression bonding is performed so that the surface of the insulating resin layer 3 is in close contact. Thereafter, a negative film having a resist pattern is brought into close contact with the surface of the first protective film 1 and irradiated with ultraviolet rays using an ultraviolet exposure device. Then the first
The protective film 1 is peeled off, developed, and unexposed portions are dissolved and removed, and the photo via hole 7 as shown in FIG.
To form Thereafter, heat curing is performed to form an insulating resin layer 3 made of a cured film of a predetermined pattern having an uneven surface on which the uneven surface 2 of the first protective film 1 is transferred.

Next, as shown in FIG. 2D, the uneven surface of the insulating resin layer 3 is subjected to chemical plating and electroplating to cover the plating layer 8, and is etched according to a predetermined pattern according to a conventional method. To form a second-layer conductive circuit. According to the method for manufacturing a multilayer printed wiring board of the present invention, since there is no roughening step as in the conventional method, fine powder particles as shown in FIG. 5B and epoxy resin as shown in FIG. Conductive circuit 6 between layers caused by pinholes caused by powder
Can be reliably prevented. In this example, an example using a single-sided printed wiring board has been described. However, the present invention can be similarly applied using a double-sided board. Needless to say, by repeating the above steps, a multilayer printed wiring board can be manufactured.

Hereinafter, an example in which the effects of the present invention have been specifically confirmed will be described more specifically. However, it goes without saying that the present invention is not limited to the following examples.

Example 1 First, as shown in FIG. 1 (a), the center line average roughness (Ra) of the uneven portion was 1 μm ≦
Ra ≦ 5 μm, and the count value (n) of the average height (Rc) of the unevenness of the roughness curve at a length of 2.5 mm on the surface is 500 or more when 0.1 μm ≦ Rc ≦ 10 μm, and 0.1 μm ≦ Irregularity processing was performed by the sandblasting method so that the number of pieces was 2500 or more when Rc ≦ 1 μm. In the film having the uneven surface 2 formed in this way,
As shown in FIG. 1B, a photo-curable and thermo-curable resin composition (manufactured by Taiyo Ink Manufacturing Co., Ltd., PV
I-500 / SA-50) with an applicator to 50μ
m and dried with a hot air drier at 80 ° C. for 15 minutes to form an insulating resin layer 3. Next, a PET film having a thickness of 50 μm obtained by baking and coating silicone is adhered to the insulating resin layer 3 as a second protective film to form an alkali developing dry film for a multilayer printed wiring board as shown in FIG. Produced.

Next, the copper-clad laminate was etched to prepare a single-sided printed wiring board having a conductor circuit 6 formed on a substrate 5 as shown in FIG. 2A. Next, the second protective film 4 of the alkali-developable dry film for a multilayer printed wiring board obtained by the process of FIG. 1 was peeled off, and as shown in FIG. 2B, the conductor circuit 6 was formed. Thermocompression bonding was performed so that the surface of the insulating resin layer 3 was in close contact with the substrate 5.
Next, a negative film having a resist pattern is
The protective film 1 was in close contact with the surface of the protective film 1 and was exposed to ultraviolet light (exposure amount 500 mJ / c) using an ultraviolet light exposure device (Oak Manufacturing Co., Ltd., model HMW-680GW).
m ² ). Subsequently, development was performed with a 1% aqueous solution of sodium carbonate for 60 seconds at a spray pressure of 2.0 kg / cm ² , and the unexposed portions were dissolved and removed, thereby forming photo via holes 7 as shown in FIG. 2C. Thereafter, heat curing is performed for 60 minutes in a hot-air dryer at 150 ° C., and the insulating resin layer 3 made of a cured film having a predetermined pattern having an uneven surface on which the uneven surface 2 of the first protective film 1 is transferred is formed. Formed.

Next, as shown in FIG. 2D, chemical plating and electroplating were performed on the uneven surface of the insulating resin layer 3 to cover the plating layer 8. FIG. 3 shows the structure of the evaluation substrate thus manufactured. In FIG. 3, the left half from the center line is an insulating portion, and the right half where a photo via hole is formed is a conducting portion. Next, when the electrical insulation of the 10 evaluation substrates thus manufactured was evaluated, the conduction hole portion showed good electrical conductivity, and the insulating portion showed good electrical insulation with an average insulation resistance of 1.8 × 10 ^12. Was. In addition, as shown in FIG. 4, the connection terminal 20 was mounted on the plating layer 8, the portion of the conductor circuit 6 was held by the connection gripper 21, and the measurement was performed with an insulation resistor.

Comparative Example 1 A comparative evaluation substrate was prepared by a method including a roughening treatment step using an acid as shown in FIG.
First, a single-sided printed wiring board similar to that of Example 1 was prepared. Next, the photo-curable and thermo-curable resin composition (manufactured by Taiyo Ink Mfg. Co., Ltd., PVI-500 / SA-50) was applied to the single-sided printed wiring board, and dried at 80 ° C. for 15 minutes using a hot air drier. Then, in order to make the conditions the same, the same silicone as the first protective film having no uneven surface was baked and coated with a PET having a thickness of 50 μm.
The film was brought into close contact with the dried coating film, and further a negative film having a resist pattern was brought into close contact with the surface of the film, and an ultraviolet exposure apparatus (Oak Manufacturing Co., Ltd., Model H
MW-680 GW) (ultraviolet light irradiation: 500 mJ / cm ² ). Subsequently, development was performed with a 1% aqueous solution of sodium carbonate for 60 seconds at a spray pressure of 2.0 kg / cm ² , and the unexposed portions were dissolved and removed, thereby forming photo via holes 7 as shown in FIG. 2C. Then 150
The composition was heated and cured in a hot air drier at 60 ° C. for 60 minutes. Then
Using a potassium permanganate solution, a surface roughening treatment was performed by a conventional method to form a concave portion 10 on the surface of the fine powder-containing resin insulating layer 9 as shown in FIG.

Next, as shown in FIG. 5D, the surface of the insulating resin layer 9 containing the fine powder in which the recess 10 is formed is subjected to chemical plating and electroplating to cover the plating layer 8 as shown in FIG. did. When the electrical insulation of the ten evaluation substrates thus manufactured was evaluated in the same manner as in Example 1, the conductive portions showed good electrical conductivity, but three out of the ten insulating substrates showed good electrical conductivity. Became conductive (short-circuited), and the average insulation resistance value of the remaining seven sheets also showed a low insulation property of 5.3 × 10 ⁸ .

[0038]

As described above, in the dry film for a multilayer printed wiring board of the present invention, the center line average roughness (Ra) of the uneven portion is formed on one surface of the first protective film in advance by sandblasting or the like. ) Is 1 μm ≦ Ra ≦ 5 μm, and the count value (n) of the average height (Rc) of the unevenness of the roughness curve at the length of 2.5 mm on the surface is 1 μm
≦ Rc ≦ 200 μm or more at 10 μm, 0.1 μm ≦
When Rc ≦ 1 μm, 2,000 or more uneven surfaces are formed, and an insulating resin layer is formed by applying and drying a photocurable and / or thermosetting resin composition on the uneven surface of the first protective film. In addition, since the second protective film is bonded to the resin insulating layer, the uneven surface can be provided to the resin insulating layer very easily in advance. By using such a dry film for a multilayer printed wiring board, the surface already has an uneven surface when the insulating resin layer is pressed on the substrate on which the conductive circuit is formed. It is possible to form a conductor circuit by covering the plating layer with good adhesion without roughening treatment as described above, so that there is no occurrence of pinholes, there is no short circuit between conductor circuits, and reliable interlayer bonding A multilayer printed wiring board having excellent strength can be provided. Further, since the surface roughening treatment is not required, the manufacturing process of the multilayer printed wiring board is shortened, and the generation of waste generated by the surface roughening treatment is eliminated, thereby reducing the influence on the environment.

[Brief description of the drawings]

FIG. 1 is a partial sectional view schematically showing one embodiment of a manufacturing process of a dry film for a multilayer printed wiring board according to the present invention in the order of processes.

FIG. 2 is a partial sectional view schematically showing one embodiment of a method for manufacturing a multilayer printed wiring board according to the present invention in the order of steps.

FIGS. 3A and 3B show schematic configurations of evaluation boards of Example 1 and Comparative Example 1 manufactured by a method for manufacturing a multilayer printed wiring board of the present invention and a conventional method for manufacturing a multilayer printed wiring board, respectively.
Is a plan view, and (b) is a sectional view.

FIG. 4 is a schematic configuration diagram illustrating a method for measuring the insulation resistance of an evaluation substrate manufactured in Example 1 and Comparative Example 1.

FIG. 5 is a partial cross-sectional view schematically showing an example of a conventional method for manufacturing a multilayer printed wiring board in the order of steps.

FIG. 6 is a partial cross-sectional view schematically showing another example of a conventional method for manufacturing a multilayer printed wiring board in the order of steps.

[Description of Signs] 1 First protective film 2 Uneven surface 3 Insulating resin layer made of photocurable and / or thermosetting resin composition 4 Second protective film 5 Substrate 6 Conductor circuit 7 Photovia hole 8 Plating layer 9 Fine Insulating resin layer containing powder 10 Depression 11 Pinhole 12 Insulating resin layer made of heat-resistant epoxy resin 13 Epoxy resin powder

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E343 AA07 BB24 BB67 CC01 CC44 DD33 DD43 DD76 EE37 GG14 5E346 CC32 DD02 DD12 DD25 EE08 GG15 GG22 HH08

Claims (6)

[Claims] 1. A method according to claim 1, wherein the surface has a center line average roughness (Ra) of 1 μm ≦ Ra ≦ 5 μm, and an average height of roughness of a roughness curve at a length of 2.5 mm on the surface. The count value (n) of Rc) is 1 μm ≦ Rc ≦ 10 μ
a first protective film in which at least 200 irregularities are formed at m, and at least 2000 irregularities are formed at 0.1 μm ≦ Rc ≦ 1 μm; and photocurability laminated on the irregularities of the first protective film; A dry film for a multilayer printed wiring board, comprising: an insulating resin layer made of a dried thermosetting resin composition; and a second protective film laminated on the insulating resin layer. 2. The second protective film of the dry film for a multilayer printed wiring board according to claim 1, which is peeled off and thermocompression-bonded onto a substrate on which a conductive circuit is formed so that the surface of the insulating resin layer is in close contact. After the step and the film having the resist pattern is brought into close contact with the first protective film surface and exposed,
Peeling off the first protective film, developing to form a photo via hole, heating and curing the insulating resin layer, and coating the surface of the heat-cured insulating resin layer with a plating layer to form a predetermined pattern. Forming a conductive circuit by etching according to the following. 3. A dry film for a multilayer printed wiring board according to claim 1, wherein the second protective film is peeled off and thermocompression-bonded onto a substrate on which a conductive circuit is formed so that the surface of the insulating resin layer is in close contact. A step of, after cooling or exposing the entire surface, peeling off the first protective film, heating the insulating resin layer or exposing the entire surface to cure, and selectively applying a laser beam to the cured insulating resin layer. Forming a via hole by irradiating, and covering the surface of the insulating resin layer having the via hole with a plating layer, and then etching according to a predetermined pattern to form a conductor circuit. A method for manufacturing a multilayer printed wiring board. 4. A dry film for a multilayer printed wiring board according to claim 1, wherein the second protective film is peeled off and thermocompression-bonded onto a substrate on which a conductive circuit is formed so that the surface of the insulating resin layer is in close contact with the second protective film. Heating the insulating resin layer or exposing the entire surface to cure, and removing the first protective film, and selectively irradiating the cured insulating resin layer with a laser beam to form a via hole. And a step of forming a conductor circuit by covering a surface of the insulating resin layer with the via hole with a plating layer, and then etching according to a predetermined pattern. 5. A dry film for a multilayer printed wiring board according to claim 1, wherein the second protective film is peeled off and thermocompression-bonded onto a substrate on which a conductive circuit is formed so that the surface of the insulating resin layer is in close contact. Removing the first protective film and heating and curing the insulating resin layer; selectively irradiating the heat-cured insulating resin layer with laser light to form a via hole; and forming the via hole. Forming a conductive circuit by coating the surface of the insulating resin layer with a plating layer, and then etching according to a predetermined pattern to form a conductive circuit. 6. A multilayer printed wiring board in which a conductive circuit is formed on a wiring board via an insulating resin layer, wherein at least a surface of the insulating resin layer opposite to the wiring board has a center line average roughness of an uneven portion. The height (Ra) is 1 μm ≦ Ra ≦ 5 μm, and the count value (n) of the average height (Rc) of the unevenness of the roughness curve at the length of 2.5 mm on the surface is 1 μm ≦
200 or more at Rc ≦ 10 μm, 0.1 μm ≦ R
A multilayer printed wiring board, wherein at least 2000 irregularities are formed when c ≦ 1 μm, and a conductor circuit is laminated on the irregularities.