JPH0685465B2 - Method of manufacturing electromagnetic shield wiring board - Google Patents

Description

The present invention relates to a novel method for manufacturing an electromagnetic shield wiring board.

[Conventional technology]

In recent years, the problem of electromagnetic wave noise (hereinafter simply referred to as noise) generated from various electronic devices such as OA devices has begun to be emphasized, and demands for noise prevention measures are increasing.

As one of means for preventing such noise, an electromagnetic shield wiring board in which a conductive layer is formed on the surface of a printed wiring board which causes noise is proposed. The above electromagnetic shield wiring board requires an insulating layer between the printed wiring circuit pattern and the conductive layer in order to prevent a short circuit between the printed wiring circuit patterns.

Conventionally, the formation of the insulating layer has been performed by screen-printing a thermosetting or photocurable epoxy type insulating resist and curing it. However, as the pattern density of the printed wiring board becomes more sophisticated, a layer of a photo-curable material having an insulating property is formed on the surface of the substrate, and this is exposed and developed to form a more precise insulating layer. A means of forming is needed.

[Problems to be Solved by the Present Invention]

However, the method of exposing and developing this using a photo-curable material is such that the side wall of the insulating layer to be formed easily becomes an undercut, and when the conductive paste is subsequently laminated, the conductive paste should be filled in the part. Will be difficult. Therefore, the conductive paste is cured while air bubbles remain between the layer of the photo-curable material filled in the portion and the lower portion of the side wall of the insulating layer. As a result, pinholes and the like are generated in the insulating layer, which causes defective products due to poor contact between the conductive layer and the ground pattern on the printed wiring board.

[Means for solving problems]

As a result of earnest studies to solve such problems, the present inventors have found that a layer of two or more types of photo-curable materials having different photosensitivities and / or development rates is formed on a printed wiring board as a cured product after development. By forming so that the remaining amount decreases toward the surface and the side wall of the insulating layer that is formed spreads toward the surface, it is possible to conduct without causing bubbles to remain in that part. The inventors have found that a layer can be formed and completed the present invention.

The present invention, when an electromagnetic shield wiring board is manufactured by sequentially laminating an insulating layer and a conductive layer on a printed wiring board, the printed wiring board is provided with two or more layers of light having different photosensitivities and / or development rates. After stacking layers of curable insulating material so that the residual amount of the cured layer after exposure and development decreases toward the surface, exposure and development are performed to form an insulating layer in which the sidewalls spread toward the surface. It is a manufacturing method of an electromagnetic shield wiring board characterized by forming.

In the present invention, the printed wiring board having a known structure is used without particular limitation. For example, a glass epoxy composite, a composite such as a paper-phenolic resin composite, a plastic film, or a three-dimensional molded article such as metal, a plate or a film as a support, on which an additive method, a subtractive method, a die stamping method, Generally, a conductive pattern is formed by a method such as a flash method. As such a printed wiring board, one having a wiring pattern on one side or both sides, or one having a laminated multilayer wiring pattern structure is used without particular limitation.

In the above-mentioned printed wiring board, a circuit requiring electromagnetic shielding is, for example, a circuit wiring for transmitting a high frequency current such as a digital signal or a circuit wiring susceptible to a high frequency noise from the outside. In the present invention, the electromagnetic shield countermeasure by forming the conductive layer is not limited to the case where the circuit wiring requiring the electromagnetic shield which exists in a dispersed manner as in the conventional case is subjected to the countermeasure, but the circuit requiring the countermeasure is provided on one side by CAD or the like. Including the case where the electromagnetic shielding is performed economically and effectively by concentrating on the one side and only one side shield measures.

In the present invention, the photocurable insulating material is not particularly limited as long as it is hardened by an actinic ray such as visible light, ultraviolet rays, and X-rays, and the hardened material has an insulating property. Generally, a compound comprising (a) a polymerizable unsaturated compound, (b) a photopolymerization initiator and a polymer binder is used.

As the above-mentioned polymerizable unsaturated compound, known compounds capable of radical polymerization are used without particular limitation. An example of a suitable polymerizable unsaturated compound is an epoxy group-containing unsaturated compound obtained by addition reaction of triglycidyl isocyanurate and an unsaturated group-containing monocarboxylic acid in an acid equivalent / epoxy equivalent ratio of 0.3 to 0.9. Compound, epoxy group / equivalent of novolak type epoxy resin and ethylenically unsaturated carboxylic acid 0.
At least 1 selected from the group consisting of esterified resin, orthocresol novolak type epoxy resin, phenol novolak type epoxy resin and halogenated phenol novolak type epoxy resin by reacting with 8 to 1.3 equivalents.
Isocyanatoethylmethacrylate is added to the secondary hydroxyl group of the unsaturated compound obtained by the addition reaction of one type of novolak type epoxy resin and the unsaturated carboxylic acid in the acid equivalent / epoxy equivalent ratio range of 0.1 to 0.9. Unsaturated compound obtained by reacting at a hydroxyl group / hydroxyl equivalent ratio in the range of 0.1 to 1.2, an epoxy resin having at least two terminal epoxy groups, and about 1 epoxy equivalent of this epoxy resin.
After reacting 0.7 to 1.5 mol of an unsaturated carboxylic acid having one ethylene bond, 0.2 to 1 per epoxy equivalent is further added.
Unsaturated group-containing epoxy resins derived from epoxy resins such as unsaturated compounds obtained by reacting with moles of polybasic acid anhydride and trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolpropane diacrylate , Trimethylolpropane dimethacrylate, tetramethylolmethane triacrylate, tetramethylolmethane trimethacrylate, tetramethylolmethane trimethacrylate, tetramethylolpropane tetraacrylate, tetramethylolpropane tetramethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol Pentaacrylate, dipentaerythritol pentamethacrylate, 1,1,1-tri (acetic acid) Polyfunctional monomers such as Lilo propoxy methyl) propane.

Also, the photopolymerization initiator is not particularly limited. For example, benzophenones such as benzophenone, 4,4-dimethylaminobenzophenone, 4,4′-diethylaminobenzophenone, 2-ethylanthraquinone, tert-
Anthraquinones such as butyl anthraquinone, benzoyl alkyl ethers such as benzoin ethyl ether and benzoin propyl ether, 2,2-dimethoxy-
2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-chlorothioxanthone, diethylthioxanthone, 2-hydroxy-2-methylpropionophenone, 4'-isopropyl-2-hydroxy-2-methylpropione Ofenone, 2-methyl-1- [4- (methylthio) -phenyl] -2-morpholino-1-propane and the like can be mentioned, and these can be used alone or in combination of two or more.

Further, as the polymer binder, known ones which are soluble in an alkaline aqueous solution or an organic solvent are used without particular limitation. Among them, those which are soluble in an alkaline aqueous solution and insoluble in water, for example, a polymer having an alkali-solubilizing group such as a carboxyl group, a carboxylic acid anhydride group, a sulfonic acid group and a sulfonamide group are preferably used. . These polymer binders are described in, for example, JP-A-59-151152, JP-A-58-42040 and JP-A-48-73148. Generally, a copolymer of a vinyl monomer and a carboxylic acid or acid anhydride having one unsaturated group selected from the group consisting of methacrylic acid, acrylic acid, itaconic acid, crotonic acid and maleic anhydride is used. It

Among them, particularly preferable examples of the polymer binder are as follows: methyl methacrylate / ethyl acrylate / methacrylic acid copolymer, methyl methacrylate / ethyl acrylate / acrylic acid copolymer, methyl methacrylate / butyl methacrylate / 2- Examples thereof include hydroxyethyl acrylate / butyl methacrylate / methacrylic acid copolymer and methyl methacrylate / tripromophenyl acrylate / methacrylic acid copolymer. Further, these polymer binders preferably have a carboxyl group content of 10 to 50 mol%.

The above-mentioned photocurable insulating material, if necessary, a filler,
You may mix | blend a polymerization inhibitor, a dye, a pigment, a solvent, etc.

In the present invention, the layer made of the above-mentioned photocurable insulating material on the printed wiring board is exposed to at least two types of layers having different photosensitivity and / or development rate, and the residual amount of the cured layer after development is on the surface. It is formed by stacking so as to decrease toward the bottom.

In the present invention, the laminated photo-curable insulating material
The difference in the photosensitivity between the layers depends on the Stoufar 40-step step.
Grayscale method using a pt-bratt (hereinafter simply referred to as
The value measured by the Rayscale method). Scarecrow
Quantitative determination of photosensitivity by the grayscale method
Shiro, Hideo Inui, "Photosensitive Polymer", P.50 (Kodansha)
It is carried out according to the method described above. That is, a commercially available copper clad laminate
The thickness of the photocurable insulating material after drying is 25 μm.
, Evaluation sample that was applied using a doctor blade
Used as. The gray scale used in this method is
Stouffer ) 40-step step plate
To use. The exposure is done through this step tablet and the
Curing remaining on the copper-clad laminate after development at 50%
From the body, the number of steps (sensitivity) that corresponds to the step
read. For example, up to the 25th step of the step plate
If the compound remains and the 26th step is washed away by development.
In this case, the sensitivity of the photocurable insulating material of this sample is read as 25 steps.
In addition, a laminated photo-curable insulating material is used.
Use one of the samples to perform 15 to 25 steps according to the above procedure.
Adjust the exposure dose to obtain the sensitivity and
Other photo-curable layer laminated on this, using light and development conditions
The sensitivity of the insulating material is also measured under the same conditions.

The developing rate of the photocurable insulating material is a value measured by the following method.

That is, a developer suitable for the photocurable insulating material, for example, a 1% Na ₂ CO ₃ aqueous solution is used in the case of a water-soluble photocurable insulating material, and a spray developing solution having a cone type nozzle is used to visually check the surface of the substrate. Place a substrate coated with unexposed photo-curable insulation material in a 25 μm-thick area of 25 cm × 25 cm at a position where the remaining amount of photo-curable insulation material can be confirmed, and spray a developing solution at a temperature of 30 ° C. with a spray pressure of 1/4 kg. Develop at / cm ² . At this time, assuming that the time until the photo-curable insulating material is just washed from the substrate surface is t (second), t (second) is the developing time (break point 100%). The development time required for sensitivity measurement is 2 t (seconds) under the same development conditions. (Breakpoint 50%). This 2t (second) is often adopted as the optimum development time of the photocurable insulating material.

Based on the method for measuring the development time, the difference in the development speed between the layers of the photo-curable insulating material laminated on the printed wiring board is the development time of the surface layer (t1) and the layer on the printed wiring board side. It is represented by the ratio (t1 / t2) to the development time (t2).

When a dry film which is a solid is used as the photocurable insulating material, the sensitivity and development rate of the dry film are measured by first dissolving the resist portion in a good solvent and then evaluating it in the same manner as the liquid resist.

In the present invention, in order to reduce the residual amount of the cured layer toward the surface due to the difference in photosensitivity between the layers made of the photocurable insulating material, the number of stages (X) showing the difference in sensitivity described above is used. , 1 to 15, preferably 3 to 9, and the number of steps decreases toward the surface. When the difference in the number of steps is less than 1, it becomes difficult to reduce the residual amount of the cured layer toward the surface when the layer made of the photocurable insulating material is exposed and developed.
On the other hand, when the difference in the number of steps is larger than 15, the degree of development of the layer is lowered and it becomes difficult to form a high density pattern.
In this case, the difference in the developing speed between the layers is that t1 / t2 is 0.1-
It is preferably in the range of 10.

Further, in order to reduce the residual amount of the cured layer toward the surface due to the difference in the development speed between the layers made of the photocurable insulating material, the above-mentioned t1 / t2 ratio is 0.1 to 1, preferably The developing speed of each layer may be adjusted so as to be 0.5 to 0.8. When the ratio of the development rate is less than 0.1, it becomes difficult to reduce the residual amount of the cured layer toward the surface when the layer made of the photocurable insulating material is exposed and developed, and the development rate When the ratio is 1 or more, the degree of development of the layer is lowered and it becomes difficult to form a high-density pattern. In this case, it is preferable to set the difference (X) in the number of steps indicating the above-mentioned sensitivity between the layers to be −10 to 15.

Of course, the difference in the photosensitivity between the layers of the photocurable insulating material and the difference in the development speed are taken into consideration, and the photosensitivity and the development of each layer are decreased so that the residual amount of the cured layer after exposure and development of the layer decreases toward the surface. It is also possible to adjust the speed.

The photosensitivity or development rate of the above-mentioned photocurable insulating material can be adjusted by changing the composition ratio of the polymerizable unsaturated compound, the photopolymerization initiator and the polymer binder, the type of each component, and the like. . That is, the photosensitivity can be changed particularly by the compounding ratio of the photopolymerization initiator, and the development rate can be changed to some extent by the chemical structure of the polymerizable unsaturated compound, but mainly It can be adjusted by changing the carboxyl group content of the molecular binder. Further, it may be changed depending on the molecular weight of the polymer binder and the hydrophilicity of the comonomer.

Generally, the composition ratio of each component is such that the polymer binder is 50 to 300 parts by weight, preferably 100 to parts by weight of the polymerizable unsaturated compound,
In the range of 100 to 200 parts by weight, the photopolymerization initiator is 0.1 to 20% by weight, preferably 3 to 10% by weight, based on the total amount of the polymerizable unsaturated compound and the polymer binder. It is preferable to determine within the range.

In the present invention, the method of laminating the photocurable insulating material is not particularly limited as long as it satisfies the above conditions. For example, the photo-curable insulating material can be laminated on the printed wiring board in a state of a solid film, which is generally called a dry film, or a liquid state. That is, solid film-like or liquid photo-curable insulating materials having different photosensitivities and / or development rates may be laminated.
Alternatively, a liquid photo-curable insulating material and a solid film-like photo-curable insulating material having different developing rates may be laminated.
As a method of forming a layer of a liquid photo-curable insulating material, known means such as a dip coating method, a flow coating method, a screen printing method may be used without particular limitation. Further, the above layer may be formed by drying a solvent contained therein and then stacking or exposing another layer.

Of the above-mentioned lamination methods, it is preferable to use a liquid photocurable insulating material as the layer in contact with the printed wiring board. That is, by using a liquid photocurable insulating material, it is possible to further improve the adhesiveness when the printed wiring board has irregularities, through holes, or the like. Further, the liquid photo-curable insulating material, by irradiating with ultrasonic waves,
Even if there is a small through hole, it can be surely penetrated into the through hole. Such a liquid photocurable insulating material, among the composition of the photocurable insulating material,
A liquid material may be used, or it may be prepared by dissolving a photocurable insulating material in a solvent. Examples of such a solvent include methyl ethyl ketone, methyl cellosolve acetate, ethyl cellosolve acetate, cyclohexanone, methyl cellosolve, propylene glycol monomethyl ether acetate, methylene chloride, propylene glycol monomethyl ether and the like.

The thickness of the layer made of the photocurable insulating material described above is not particularly limited, but generally the thickness of each layer is 5 to 50 μm.
m, preferably 10 to 30 μm, and the thickness of all layers is preferably 100 μm or less.

In the present invention, as a method of exposing and developing a layer made of a photocurable insulating material formed on a printed wiring board, a known method is adopted without particular limitation. That is, the exposure may be performed by irradiating the layer with the above-mentioned actinic rays through a negative mask. Further, the development may be carried out by removing the uncured portion after exposure with a liquid capable of etching the uncured photocurable insulating material. The liquid is not particularly limited as long as it can dissolve the polymerizable unsaturated compound and / or the polymer binder, which is a constituent component of the photocurable insulating material, and is an alkali such as sodium phosphate or potassium phosphate. Aqueous solution of metal phosphate, alkaline solution such as aqueous solution of alkali metal carbonate such as sodium carbonate, 1,
It is used by appropriately selecting from organic solvents such as 1,1-trichloroethane, perchlorethylene, butyl cellosolve, toluene and xylene.

In addition, heat treatment at 80 to 200 ° C after development is
Adhesion of the formed insulating layer to the printed wiring board,
This is a preferred embodiment because the properties such as heat resistance and solvent resistance can be improved.

In the present invention, the insulating layer is generally formed so as to cover the wiring pattern except a part of the ground pattern terminal of the printed wiring board, the conductive via hole, and the like.

In the present invention, the conductive layer is generally formed on the surface including the insulating layer and the ground pattern on the printed wiring board.

A conductive paste is generally used for forming the conductive layer. As such a conductive paste, a known paste may be used without particular limitation. For example, epoxy resin filled with metal powder such as copper, gold, silver, nickel, carbon,
A thermosetting resin such as a phenol resin is preferably used. A conductive layer is formed by pattern-printing this on a required surface by a screen printing method or the like and curing it.

The thickness of the conductive layer is related to the electrical resistance, but usually 10μ ~ 100
It is preferable that the thickness is adjusted by screen meshing, printing conditions, number of times of printing, paste viscosity, etc.

In the present invention, it is preferable to provide an overcoat layer in order to protect the surface of the electromagnetic shield wiring board obtained by the above method from the external environment. It is preferable that the material of the overcoat layer has properties such as heat resistance, chemical resistance, surface hardness, moisture resistance, and high electric insulation.

Generally, a thermosetting resin, a ur curable resin, or the like, which is commercially available as a solder mask and is pasted with an epoxy resin, is used. Of course, the photocurable insulating material of the present invention can also be used as the overcoat layer.

The method of the present invention will be specifically described with reference to FIG.

FIG. 1 is a treatment process showing a typical aspect of a method for producing an electromagnetic shield wiring board by the method of the present invention. FIG. 1 is a treatment step showing a representative aspect of a method for producing an electromagnetic shield wiring board by the method of the present invention. It is a figure. That is,
In (a), a layer 4-a is formed of a liquid photocurable insulating material on the substrate 1 having the wiring pattern 2 and the ground pattern 5, and then in (b), with respect to the layer 4-a. A layer 4-b made of a photo-curable insulating material in the form of a solid film having a difference in photosensitivity and / or development speed is laminated. In addition, 3 is a through hole. Then, the substrate is exposed through a photomask and then developed to obtain a wiring board having an insulating layer in a necessary portion as shown in (c). Since such an insulating layer is formed so that the residual amount of the hardened layer decreases toward the surface, the side wall is in a state of spreading toward the surface. Therefore, in (d),
Conductive paste 6 on the insulating layer without entraining gas
Can be laminated and cured to obtain a good electromagnetic shield wiring board.

〔effect〕

As can be understood from the above description, according to the present invention, an insulating layer in which a sidewall expands upward by using a specific photocurable insulating material in combination on a wiring pattern of a printed wiring board. Is formed. for that reason,
When the conductive layer is formed so as to cover the insulating layer, it is possible to completely prevent the gas from remaining below the sidewall of the insulating layer. Therefore, even if the printed wiring board has a high-density wiring pattern, an insulating layer,
The conductive layer can be reliably formed, and the reliability of the obtained electromagnetic shield wiring board can be significantly improved.

〔Example〕

EXAMPLES Hereinafter, examples will be shown to more specifically describe the present invention, but the present invention is not limited to these examples.

In addition, the display of "part" shows a weight part. In addition, specific methods for measuring the photosensitivity and the developing time in the examples are as follows.

(1) Sensitivity measurement A solution of a photo-curable insulating material is applied on a copper clad laminate and dried at room temperature for 20 minutes and at 80 ° C for 10 minutes to form a 25-µm-thick layer of photo-curable insulating material. did. Then, through the Stoufar 40-step step plate, the HMW-6 manufactured by Oak Manufacturing Co., Ltd.
Exposure was performed at 500 mt / cm ² using an N type high pressure mercury lamp exposure machine. After the exposure, the film was allowed to stand for 10 minutes, then spray-developed for 60 seconds using a 1 wt% sodium carbonate aqueous solution (30 ° C.) (break point 50%), and immediately washed with spray water for 60 seconds. The sensitivity was read from the remaining cured material.

(2) Measurement of development speed A photo-curable insulating material solution is applied on a copper clad laminate and dried at room temperature for 20 minutes and at 80 ° C for 10 minutes to obtain a thickness of 25 μm and a size of 20 cm ×
A 20 cm layer was formed. In the unexposed state, a 1% sodium carbonate aqueous solution (30 ° C.) was used for spray development at a spray pressure of 14 kg / cm ² , and the time t until the photocurable insulating material was completely dissolved and removed from the copper surface was determined. It was measured.

Example 1. (a) Synthesis of polymerizable unsaturated compound A.TEPIC-G (triglycidyl isocyanurate manufactured by Nissan Chemical Industries, Ltd., epoxy equivalent 110) 110 parts B. methacrylic acid 57 parts P-methoxyphenol 0.1 part C. Propylene glycol monomethyl ether 53 parts D. Methyl violet 0.01 part The above compound A was heated to 140 ° C and uniformly dissolved, and then 1
After cooling to 10 ° C and maintaining the temperature at 110 ° C, the compound B was added dropwise over 1 hour. After dropping the B compound, the acid value of the reaction system was reduced to 1 or less at 110 ° C., and then the C compound was added, and triglycidyl isocyanurate having a nonvolatile content of 75% by weight / acrylic acid (acid equivalent / epoxy equivalent ratio = 2 / 3) A solution (1) of a polymerizable unsaturated compound containing an epoxy group was obtained.

(B) Preparation of Photocurable Insulating Material (1) 87 parts of solution of polymerizable unsaturated compound obtained in (a) (66 parts of solid content), methyl methacrylate / butyl acrylate / methacrylic acid (70/5 (/ 25 molar ratio) 35 parts of copolymer (weight average molecular weight 80,000), 5 parts of benzophenone, 0.5 part of 4,4'-bisdiethylaminobenzophenone and 200 parts of propylene glycol monomethyl ether were mixed and uniformly stirred and dissolved. .

The photosensitivity of the above photo-curable materials is 25 steps, break point
The development time at 100% was 30 seconds.

(C) Preparation of Photocurable Insulating Material (2) A resist (2) was prepared in the same manner as in the above (b) except that 3 parts of benzophenone and 0.1 part of 4,4′-bisdiethylaminobenzophenone were used. .

The sensitivity of the above photo-curable insulating material is 19 steps, break point
The development time at 100% was 30 seconds.

(D) Formation of shield plate A photo-curable insulating material (1) solution was applied to a patterned etching substrate (FR-4, copper clad laminate), and it was applied at room temperature for 20
Min, and dried at 80 ° C. for 10 minutes to form a resist layer having a thickness of 25 μm. Then, in the same way, 25μ of photo-curable insulating material (2)
A layer of m was formed on the resist (1). Then, it was exposed at 800 mt / cm ² through a negative mask. After leaving for 10 minutes after the exposure, a 1% aqueous sodium carbonate solution was used for spray development at 30 ° C. for 100 seconds (break point 50%), and immediately washed with spray water for 60 seconds. The sensitivity showed 22 steps. Then
After heat treatment at 150 ° C for 30 minutes, an insulating layer with excellent dimensional accuracy corresponding to a negative mask was obtained. Observation of the solidification of the insulating layer with a scanning electron microscope revealed that the side walls spread upward.

Then, a shield pattern was formed on the insulating resist. Then, it heat-processed at 180 degreeC for 30 minutes, the copper paste was hardened | cured, and the electromagnetic shield wiring board was obtained.

When 10 pieces of electromagnetic shield wiring boards were manufactured by the above-mentioned method, there was no defective conduction between the copper paste shield layer and the copper foil ground line in the inspection by the conduction checker.

Example 2. (a) Preparation of photocurable insulating material (3) 87 parts of solution of the epoxy group-containing polymerizable unsaturated compound obtained in Example 1- (a) (solid content 66 parts), methacrylic acid Methyl / butyl acrylate / methacrylic acid (60/5/35
(Mole ratio) 35 parts of a copolymer (weight average molecular weight of 80,000), 5 parts of benzophenone, 0.5 part of 4,4'-bisdiethylaminobenzophenone, and 200 parts of propylene glycol monomethyl ether were mixed and uniformly stirred and dissolved.

When the developing speed and the sensitivity of the above-mentioned photocurable insulating material were measured, the developing time was 17 seconds at a breakpoint of 100%, and the sensitivity was 25 steps.

(B) Formation of shield plate Electromagnetic shield was obtained in the same manner as in Example 1- (d) except that the photo-curable insulating material (2) was used instead of the photo-curable insulating material (2). A wiring board was manufactured. When the cross section of the insulating layer after post-charge was observed with a scanning electron microscope, it was found that sidewalls that were spread upward were formed.

When 10 pieces of electromagnetic shield wiring boards were manufactured by the above-mentioned method, there was no conduction failure between the copper paste shield layer and the copper foil ground line in the inspection by the conduction checker.

Example 3. (a) Preparation of photocurable insulating material (4) 87 parts (solid content 66 parts) of the solution of the epoxy-containing polymerizable unsaturated compound obtained in Example 1- (a), methyl methacrylate / Butyl acrylate / methacrylic acid (60/5/35 molar ratio) copolymer (weight average molecular weight 80,000) 35 parts, benzophenone 3 parts, 4,4'-bisdiethylaminobenzophenone
0.1 part and propylene glycol monomethyl ether 200
Parts were mixed and uniformly dissolved by stirring.

When the developing speed and the sensitivity of the above-mentioned photocurable insulating material were measured, the developing time was 17 seconds at a breakpoint of 100%, and the sensitivity was 19 steps at 500 mt / cm ² .

(B) Formation of Shield Plate In the same manner as in Example 1- (d), except that the photocurable insulating material (4) of this Example (a) was used in place of the photocurable insulating material (2). An electromagnetic shield wiring board was manufactured.
Incidentally, after the post-charge, when the cross section of the insulating layer was observed with a scanning electron microscope, it was found that a side wall spreading upward was formed.

When 10 pieces of electromagnetic shield wiring boards were manufactured by the above-mentioned method, there was no defective conduction between the copper paste shield layer and the copper foil ground line in the inspection by the conduction checker.

Comparative Example 1. An electromagnetic shield wiring board was manufactured in the same manner as in Example 1- (d) except that the photocurable insulating material (1) was used instead of the photocurable insulating material (2).

Incidentally, in the above-mentioned production, after forming the conductive layer, observing the solidification of the insulating layer with a scanning electron microscope, while trapping air in the undercut portion of the side wall, a situation in which the copper paste was filled was observed. It was

When 10 electromagnetic shield wiring boards were manufactured by the above-mentioned method, a conduction defect between the copper paste shield layer and the copper foil ground line was found to occur at 15.3 in all the ground points in the inspection by the conduction checker.

[Brief description of drawings]

FIG. 1 is a process chart showing a typical embodiment of a method for producing an electromagnetic shield wiring board according to the present invention. In the figure, 1 is a substrate, 2 is a wiring pattern, 3 is a through hole, 4-a,
4-b is a photo-curable insulating material, 5 is a ground pattern, and 6 is a conductive paste.

Claims (1)

[Claims] 1. When manufacturing an electromagnetic shield wiring board by sequentially laminating an insulating layer and a conductive layer on a printed wiring board,
On the printed wiring board, two or more layers of a photocurable insulating material having different photosensitivities and / or development rates were laminated so that the residual amount of the cured layer after exposure and development decreased toward the surface. After that, exposure and development are performed to form an insulating layer in which the sidewalls spread toward the surface, and a method for manufacturing an electromagnetic shield wiring board.