JPH11186724A - Manufacturing multilayered printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a thin type multilayered printed wiring board which has little thickness variations and smooth surface and is suited to highdensity packaging. SOLUTION: The manufacturing method comprises the steps of applying a photo-setting/thermosetting type under-coating 3 to a flame-retardant inner layer circuit board 1 composed of a frame-retardant epoxy resin-impregnated glass cloth board, irradiating an active energy to make it tack-free, roll- laminating a Cu foil having a layer insulation adhesive layer, and heating it to cure, thereby forming a multilayered printed wiring board 7. An inner layer circuit board 1 is pre-heated to roll-laminate the Cu foil having the layer insulation adhesive layer after coating the coating 3 and making it tack-free. For roll-laminating, the under-coating 3 is heated by heating rollers up to a temp. which is sufficient to adhere the layer insulation adhesive layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel light-emitting device for multilayer printed wiring boards comprising low cost, high productivity tack-free by irradiation with active energy rays and full curing by heat.
The present invention relates to a method for manufacturing a low-cost and high-productivity multilayer printed wiring board using a copper foil having a thermosetting undercoat agent and an interlayer insulating adhesive layer.

[0002]

2. Description of the Related Art In multilayer printed wiring boards, the miniaturization and multifunctionality of electronic devices have been progressing, and the direction of higher density has been shifted. In other words, the direction of circuit thinning, via hole diameter reduction, thinning, high multilayering, and the like is progressing. Conventionally, in the production of a multilayer printed wiring board, using a hot plate press, a glass cloth base material is impregnated with epoxy resin and semi-cured on a circuit-prepared inner layer circuit board, and one or more prepreg sheets are stacked. The process of laminating a copper foil on top and performing heating integral molding is performed. However, in this step, since the impregnated resin is reflowed by heat and cured under a constant pressure, it takes 1 to 1.5 hours to uniformly cure and mold. As described above, the manufacturing process takes a long time, and the cost is high due to the costs of the multilayer laminating press and the glass cloth prepreg. In addition, the method of impregnating the glass cloth with a resin has made it difficult to make the interlayer thickness extremely thin.

In recent years, in order to solve these problems, the technique of a multilayer printed wiring board by a build-up method which does not perform hot press molding by a hot plate press and does not use a glass cloth as an interlayer insulating material has been renewed. I have. Generally, rubber-based compounds, polyvinyl butyral, phenoxy resin, polyester resin, etc. are compounded as a method of forming a film or a roll of the adhesive which is an interlayer insulating layer, but these components are used for thermal processing as a multilayer printed wiring board. Significantly degrade performance. In a multilayer printed wiring board by the build-up method, use a copper-clad insulating sheet in which an insulating resin layer is formed on the roughened surface of copper foil, or a prepreg sheet in which a glass cloth base material is impregnated with epoxy resin and semi-cured. When the interlayer insulating resin layer on the film is used instead, the working efficiency is remarkably improved as compared with the method of forming the interlayer insulating resin layer using the prepreg. However, air at the stepped portion between the insulating substrate and the circuit of the inner circuit board cannot be completely removed, and this void may cause poor insulation and deteriorated solder heat resistance, and delamination may occur. It is a problem. In order to prevent this, lamination must be performed under a reduced pressure environment, and special equipment is required.
In addition, since the laminated insulating layer follows the step between the insulating substrate and the circuit of the inner circuit board, surface smoothness cannot be obtained, soldering failure or the like may occur at the time of component mounting, or the resist may not be formed in the etching resist forming step. There were also problems such as peeling and a decrease in the pattern development degree, which prevented stable formation of a resist.

The same applies to the case where a prepreg is used. However, since the amount of resin to be embedded varies depending on the residual ratio of copper foil in the inner circuit pattern, the same copper-clad insulating sheet or film-like interlayer insulating resin layer is used. Also, the sheet thickness after molding does not become the same. In other words, when the copper foil residual ratio is large and the portion to be embedded is small, the plate thickness is large, and when the copper foil residual ratio is small and the portion to be embedded is large, the plate thickness is small. If you do not change, you cannot achieve the same thickness. In addition, when the residual ratio of copper foil is different depending on the location even in one inner layer circuit board, there is a problem that the obtained multilayer printed wiring board does not have a uniform plate thickness and the like.

[0005]

SUMMARY OF THE INVENTION The present invention is thinner, has less variation in thickness, and has a smoother surface than a multilayer printed wiring board obtained by the above-mentioned hot plate press molding method or a conventional build-up method. And a method for manufacturing a multilayer printed wiring board suitable for high-density mounting.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an optical circuit board made of a flame-retardant epoxy resin impregnated glass cloth substrate.
Production of a multilayer printed wiring board in which a thermosetting undercoat agent is applied and tack-free by irradiation with active energy rays, then a copper foil having an interlayer insulating adhesive layer is roll-laminated, and then integrally cured by heating. In the method, when roll laminating a copper foil having an interlayer insulating adhesive layer, coating of a light / thermosetting undercoat agent, preheating the inner layer circuit board after tack-free, and then during roll lamination A method for manufacturing a multilayer printed wiring board, characterized in that a heating roll is used to reach a temperature at which the photo-thermosetting undercoat agent can be softened and a temperature at which the interlayer insulating adhesive layer can be bonded. Preferably, the temperature at the time of roll lamination of the adhesive portion between the undercoat agent and the interlayer insulating adhesive layer is set to 70 to 110 ° C., and the light / thermosetting undercoat agent is (A) having a bromination ratio of 20% or more. A novolak epoxy resin having a molecular weight of 500 to 4000,
(B) a bisphenol-type epoxy resin having a molecular weight of 500 or less, (c) hydroxyethyl acrylate or hydroxyethyl methacrylate, (d) a polyfunctional acrylate monomer or a polyfunctional methacrylate monomer, (e) a photopolymerization initiator, and (f) a melting point of 130 ° C. An interlayer insulating adhesive comprising the above-mentioned imidazole compound and (g) a low-temperature curing type imidazole compound, wherein (h) a brominated bisphenol type epoxy resin or a brominated phenoxy resin having a bromination ratio of 20% or more and a weight average molecular weight of 10,000 or more. (B) a bisphenol-type epoxy resin having an epoxy equivalent of 500 or less,
And (u) a method for producing a multilayer printed wiring board as described above, comprising an imidazole compound having a melting point of 130 ° C. or higher.

That is, the present invention provides screen printing on an inner circuit board made of a glass cloth substrate impregnated with a flame-retardant epoxy resin,
A liquid undercoat agent is applied using a roller coater, a curtain coater, or the like, and the space between the copper foil circuits of the inner circuit board is filled, and the undercoat agent is made tack-free by irradiating active energy rays with a UV conveyor or the like. Tack-free by this active energy ray enables the undercoat agent to be coated on the back side, and there is no difference between front and back,
Uncured or semi-cured copper foil with an interlayer insulating adhesive layer can be easily laminated on both sides simultaneously with a heated roll or the like. Then, after lamination, heating is performed to simultaneously and integrally cure the light / thermosetting undercoat agent and the copper foil with an interlayer insulating adhesive, whereby a multilayer printed wiring board can be manufactured.

In roll lamination, the undercoat agent is softened by being heated by a hot roll, the thickness is averaged by the roll pressure, and smoothness is obtained. At this time, the interlayer insulating adhesive coated on the copper foil is bonded while maintaining its shape by the epoxy resin component having a weight average molecular weight of 10,000 or more, that is, while maintaining the interlayer thickness, and thus depends on the residual ratio of the inner layer copper foil. Thus, a multilayer printed wiring board having a small thickness variation and excellent plate thickness accuracy can be manufactured without performing the method. Further, in order to sufficiently exhibit these functions, it is important to transmit a sufficient amount of heat to the undercoat agent during roll lamination. The step of doing is indispensable.

If heat is transferred only by a high-temperature heat roll during high-speed lamination, only the interlayer insulating adhesive wound around and in close contact with the heat roll advances, and the undercoat agent does not transmit the heat and does not exhibit its function. Softening may not be possible. In addition, an excessive increase in the temperature of the heat roll may cause wrinkles of the copper foil. Therefore, it is better to heat-treat the inner layer circuit board after the application of the light / thermosetting undercoat agent and the tack-free, and to roll laminate the copper foil having the interlayer insulating adhesive layer.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an undercoat agent used for an undercoat layer fills a space between copper foil circuits of an inner circuit board and smoothes the inner circuit surface. (G). (A) a bromination ratio of 20% or more and a molecular weight of 500 to 4000;
Novolak type epoxy resin, (b) bisphenol type epoxy resin having a molecular weight of 500 or less, (c) hydroxyethyl acrylate or hydroxyethyl methacrylate, (d) polyfunctional acrylate monomer or polyfunctional methacrylate monomer (e) photopolymerization initiator, (F) An imidazole compound having a melting point of 130 ° C. or more, and (g) a low-temperature-curable imidazole compound, wherein the component (A) used in the present invention has a bromination ratio of 20% or more and a molecular weight of 500 to 4
The epoxy resin of 000 is used for improving heat resistance and flame retardancy, and is a phenol novolak type or cresol novolak type novolak type epoxy resin which is solid at room temperature. Melting point is usually 50
It is sufficient that the temperature is not less than ° C. When the bromination ratio is less than 20%, the obtained multilayer printed board has a flame retardancy V-0 according to UL standard.
Can not achieve. Further, the upper limit of the bromination ratio is a case where all the brominated portions of the benzene nucleus of the epoxy resin are brominated, and the upper limit of the bromination is determined by this.

The bisphenol-type epoxy resin having a molecular weight of 500 or less as the component (b) enhances embedding properties, wettability, etc., and improves moldability and surface smoothness. Molecular weight 5
If it exceeds 00, these effects are undesirably weakened. The photopolymerizable and heat-reactive monomer used in the photo-thermosetting undercoat agent is (c) hydroxyethyl acrylate or hydroxyethyl methacrylate. These components function as a solvent for the epoxy resin, and are used as a so-called solventless undercoat agent. The components (c) and (d) react by irradiation with active energy rays, and the undercoat layer is tack-free depending on the degree of curing. Each mixing ratio is appropriately determined between 20 and 80% by weight. Normal,
The total amount of the monomers (c) and (d) is 20 to 1 with respect to 100 parts by weight of the total amount of the epoxy resin used.
00 parts by weight, preferably 30 to 70 parts by weight.

Examples of the photopolymerization initiator (e) include benzophenones such as benzophenone, benzoylbenzoic acid, 4-phenylbenzophenone and hydroxybenzophenone, benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether and benzoin isobutyl ether. Benzoin alkyl ethers, 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 4-
acetophenones such as t-butyl-trichloroacetophenone and diethoxyacetophenone; thioxanthones such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone and 2,4-dimethylthioxanthone; ethylanthraquinone and butylanthraquinone; Alkyl anthraquinones and the like can be mentioned. These may be used alone or as a mixture of two or more. The amount of the photopolymerization initiator is usually 0.1 to 100 parts by weight of the photopolymerization and heat-reactive monomer.
It is used in the range of 10 parts by weight.

The epoxy resin curing agent (f) has a melting point of 130 ° C. or higher, is solid at room temperature, has low solubility in the epoxy resin, and rapidly reacts with the epoxy resin at a high temperature of about 150 ° C. Then, it is added to finally cure the epoxy resin. Specifically, 2
-Methylimidazole, 2-phenoxyimidazole,
2-phenyl-4-methylimidazole, bis (2-ethyl-4-methyl-imidazole), 2-phenyl-4
-Methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-hydroxymethylimidazole, and triazine-added imidazole. Epoxy adducts or microcapsules of these can also be used. These may be used alone or in combination of two or more.

As the epoxy resin curing agent (g), the epoxy resin starts a reaction from a low temperature range of 60 to 120, and this curing agent is used to cause an initial reaction of the epoxy resin. When integrally curing the undercoat agent and the interlayer insulating adhesive, it is important for the moldability to start a curing reaction from the undercoat side. Specifically used are imidazole, 2-
Ethyl-4-methylimidazole, 2-undecylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1
-Cyanoethyl-2-ethyl-4-methylimidazole, 1-aminoethyl-2-methylimidazole, 1-
(Cyanoethylaminoethyl) -2-methylimidazole, 1-cyanoethyl-2-phenyl-4,5-bis (cyanoethoxymethylimidazole) and the like,
Epoxy adducts or microcapsules of these can also be used. These may be used alone or in combination of two or more.

By using an epoxy resin or a phenoxy resin having a weight-average molecular weight of 10,000 or more for the interlayer insulating adhesive coated on the copper foil, the shape can be maintained.
In other words, since the bonding is performed while maintaining the interlayer thickness, there is no variation in the thickness of the multilayer printed wiring board without depending on the residual ratio of the inner layer copper foil, and it is possible to manufacture a multilayer printed wiring board having excellent thickness accuracy. Becomes However, this means that when laminating a copper foil with an interlayer insulating adhesive, the undercoat agent coated on the inner layer circuit board is softened by heating the hot roll, and the thickness is not averaged by the roll pressure. Cannot be realized. In addition, the softening of the undercoat agent has a great effect on the improvement of the adhesiveness with the interlayer insulating adhesive, and a fusion integration reaction can be performed at the polar interface.
This also affects the reliability between layers.

However, when the curing reaction of the undercoat agent is delayed from the curing reaction of the interlayer insulating adhesive during thermal curing, and the melt viscosity of the undercoat agent is reduced more than necessary, the curing reaction of the interlayer insulating adhesive is affected. Molding defects such as wrinkles and voids may occur. On the other hand, in the undercoat agent used in the present invention, the reaction in the low-temperature region is promoted by the component (g), and the unnecessarily lowering of the melt viscosity is suppressed. , Good smoothness, interlayer adhesion and the like can be achieved. The amount of the epoxy resin curing agent varies depending on the type of the curing agent, but is 1 to 10 parts by weight in total of the component (f) and the component (g) per 100 parts by weight of the epoxy resin,
The proportion of the component (g) is appropriately determined by the melt viscosity of the undercoat agent during heat curing.

In addition, if necessary, an ultraviolet inhibitor, a thermal polymerization inhibitor, a plasticizer, and the like can be added to the light / thermosetting undercoat agent for multilayer printed wiring boards of the present invention for storage stability. Further, an acrylate monomer, a methacrylate monomer, a vinyl monomer, or the like may be added for adjusting the viscosity. Furthermore, fused silica, crystalline silica, calcium carbonate, aluminum hydroxide, alumina,
Inorganic fillers such as barium sulfate, mica, talc, clay, white carbon, E glass powder, etc. can be blended, and epoxy silane coupling agent to improve adhesion and moisture resistance to copper foil and inner circuit board It is also possible to add an antifoaming agent for preventing voids, a so-called liquid or powdered flame retardant, and the like.

The photo-thermosetting undercoat agent for a multilayer printed wiring board of the present invention comprising these components, while being substantially solvent-free, fills a space between the copper foil circuits of the inner circuit board, Smooth the surface. Further, it becomes easily solid by irradiation with active energy rays and can be made tack-free. Component (C) in the adjusted undercoat agent of the present invention
And (d) first act as a solvent, dissolve the component (a) and other components, fill the space between the copper foil circuits of the inner circuit board, and form a varnish state in which the surface of the inner circuit circuit can be smoothed. When the components (c) and (d) acting as a solvent are cured by irradiation with an active energy ray, the components (c) and (d) lose their effect as a solvent due to solidification of the cured product. Component (a) precipitates. At this time, the cured components (c), (d) and other components are solid components (a)
Dispersed inside. Therefore, if the component (A) which is in an appropriate tack-free solid state at room temperature is selected, the undercoat agent of the present invention is tack-free without a thermosetting reaction. Such a tack-free mechanism is the greatest feature of the present invention. In addition, since the component (c) of the present invention which has been cured by irradiation with an active energy ray also has a heat-reactive functional group, it undergoes a curing reaction with an epoxy resin or a curing agent as a base agent during a subsequent heating reaction. The material is also excellent in heat resistance, chemical resistance and the like.

Next, the interlayer insulating adhesive to be coated on the copper foil used in the present invention comprises: (h) a brominated bisphenol type epoxy resin or a brominated phenoxy resin having a bromination ratio of 20% or more and a weight average molecular weight of 10,000 or more; (I) An adhesive having heat resistance and flame retardancy, comprising a bisphenol type epoxy resin having an epoxy equivalent of 500 or less and an imidazole compound having a melting point of 130 ° C. or more.

The brominated bisphenol-type epoxy resin or brominated phenoxy resin having a bromination ratio of component (h) of 20% or more and a weight average molecular weight of 10,000 or more reduces resin flow during molding and maintains the thickness of the insulating layer. The composition is added for the purpose of imparting flexibility to the composition and achieving flame retardancy of the obtained multilayer printed wiring board. In addition, the component (h) alone has a low crosslinking density after curing, has too high flexibility, and has a high viscosity when dissolved in a solvent and used as a varnish of a predetermined concentration for coating a copper foil. Workability at the time of coating deteriorates. In order to remedy these drawbacks, a bisphenol F type epoxy resin having an epoxy equivalent of 500 or less is blended as a (nu) component. The mixing ratio of the epoxy resin is as follows:
(I) Component = 50 to 70% by weight: 50 to 30% by weight. If the component (h) is less than 50% by weight, the viscosity does not increase and the thickness as an interlayer insulating adhesive cannot be maintained,
The smoothness of the outer layer circuit after lamination becomes poor,
On the other hand, if the content is more than 10% by weight, the viscosity increases, and it becomes difficult to coat the copper foil, and it is difficult to maintain a predetermined thickness. If the bromination ratio of the brominated bisphenol-type epoxy resin or brominated phenoxy resin is less than 20%, the obtained multilayer printed wiring board cannot achieve the flame retardancy V-0, so that it must be at least 20%. .

It is preferable to use the same type of curing agent as the component (v) as the component (f) used in the above-mentioned undercoat agent. That is, it has a melting point of 130 ° C. or more, is solid at room temperature, has low solubility in epoxy resin, and has a melting point of 150 ° C.
It is added because the temperature is raised to a high temperature and the epoxy resin quickly reacts with the epoxy resin and finally cures the epoxy resin. Specifically, 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, bis (2-ethyl-4-methyl-imidazole),
Examples include 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, and triazine-added imidazole. Epoxy adducts or microcapsules of these can also be used. These may be used alone or in combination of two or more. These imidazoles are finely divided and are uniformly dispersed in the epoxy resin varnish. 100 ° C due to low compatibility with epoxy resin
In the following, the reaction does not proceed, so that the varnish can maintain good storage stability. 1 for copper foil as interlayer insulating adhesive
If the coating is performed at a temperature of 00 ° C. or less, the epoxy resin remains uncured, so that the storability as the adhesive can be kept good. When laminated with an inner layer circuit board provided with an undercoat layer, and then heated to 150 ° C. or higher during curing, the epoxy resin reacts with the undercoat agent and partially melts and mixes on the contact surface. Is obtained.

In addition to the epoxy resin and the curing agent, a component that reacts with the epoxy resin or the curing agent can be mixed in the interlayer insulating adhesive. For example, epoxy-reactive diluents (such as phenylglycidyl ether as a monofunctional type, resorcing ricidyl ether and ethyleneglycol glycidyl ether as a bifunctional type, and glycerol triglycidyl ether as a trifunctional type), resole type or novolak type phenolic resins And isocyanate compounds. In addition to the above components, in order to improve the coefficient of linear expansion, heat resistance, flame resistance, etc., fused silica, crystalline silica, calcium carbonate, aluminum hydroxide, alumina, barium sulfate, mica, talc, clay, white carbon, E
Add inorganic filler such as glass powder to epoxy resin.
You may mix | blend 0 weight% or less. If the content is more than 40% by weight, the viscosity of the adhesive increases, and the adhesiveness decreases.
Further, an epoxy silane coupling agent for improving the adhesion to the copper foil and moisture resistance, an antifoaming agent for preventing voids, or a liquid or powdered flame retardant may be added. As a solvent, apply an adhesive to copper foil
After drying at 130 ° C., one that does not remain in the adhesive must be selected. For example, acetone, methyl ethyl ketone, toluene, xylene, n-hexane,
Methanol, ethanol, methylcellosolve, cyclohexanone and the like.

The copper foil with an interlayer insulating adhesive is prepared by applying an adhesive varnish obtained by dissolving an adhesive component in a predetermined solvent at a predetermined concentration on an anchor surface of the copper foil, and then drying the copper foil at 80 to 130 ° C. It is manufactured so that no solvent remains in the adhesive.
The thickness of the adhesive layer is preferably from 15 to 120 μm. 1
If the thickness is less than 5 μm, the interlayer insulating property may be insufficient. If the thickness is more than 120 μm, there is no problem with the interlayer insulating property. However, the production becomes difficult, and the purpose of the present invention of reducing the thickness of the multilayer board is not met.

An outline of a method of applying an undercoat agent and laminating and curing a copper foil with an interlayer insulating adhesive to achieve the object of the present invention will be described with reference to FIG. (A) A liquid undercoating agent (3) is screen-printed on the inner layer circuit board (1), and one side of the inner layer circuit (2) is completely coated using a conventional coating equipment such as a roller coater or a curtain coater. Apply to the thickness to cover. If the embedding amount is insufficient, air will be entrained in the subsequent laminate. Then, it is made tack-free by irradiating active energy rays with a UV irradiation conveyor or the like. Next, the other surface of the inner circuit board (2) is coated with an undercoating agent (3) in the same manner. (B) A copper foil (5) with an interlayer insulating adhesive (4) is laminated on the surface. The laminator uses a roll (6) coated with a pair of silicon rubber or the like to achieve surface smoothness, and is laminated on both sides of the inner circuit board (2). Varies depending on the pattern of the inner layer circuit as a laminated condition, the degree pressure 0.5~6kgf / cm ² ▲ ▼, surface temperature 100 ° C. of about from room temperature, the laminate speed 0.1
Perform at about 6 m / min. Under such conditions, the photocurable undercoat agent can achieve surface smoothness by using a hard roll. At this time, the inner layer circuit (2)
The interlayer thickness between the metal foil and the copper foil (5) can be achieved by the thickness of the interlayer insulating adhesive. At this time, the undercoat agent (3)
It is better to roll laminate a copper foil with an interlayer insulating adhesive layer (4) while preheating the inner layer circuit board (2) after coating and tack-free. (C) Next, a simultaneous integrated curing reaction is performed by heating to form a multilayer printed wiring board (7) in which an undercoat agent (3) and an interlayer insulating adhesive (4) coated on a copper foil are integrally formed. can do.

[0025]

The present invention will be described below with reference to examples.
"Parts" represents parts by weight. Example 1 1000 parts of a brominated phenoxy resin (25% brominated, weight average molecular weight: 60000) and 400 parts of a bisphenol F type epoxy resin (epoxy equivalent: 175, Epicron 830 manufactured by Dainippon Ink and Chemicals, Inc.) were added to MEK2.
Dissolve in 000 parts with stirring and add 2
-Phenyl-4-methyl-5-hydroxymethylimidazole (4 parts) and a silane coupling agent (Nihon Unicar Co., Ltd.)
A-187) 20 parts was added to prepare an interlayer insulating adhesive varnish. The varnish was applied to an anchor surface of a copper foil having a thickness of 18 μm by a roller coater so that the thickness after drying became 40 μm, and dried to prepare a copper foil with an interlayer insulating adhesive. Next, 100 parts of brominated phenol novolak epoxy resin (35% brominated, epoxy equivalent 280, weight average molecular weight 1400), 10 parts of bisphenol A type epoxy resin (epoxy equivalent 950, weight average molecular weight 1600) 10
0 parts and a bisphenol F type epoxy resin (epoxy equivalent: 175, Epicron 83 manufactured by Dainippon Ink and Chemicals, Inc.)
0) 40 parts were dissolved in 80 parts of glycidyl methacrylate and 80 parts of hydroxyethyl methacrylate, and as a curing agent, 4 parts of 2-phenyl-4-methyl-5-hydroxymethylimidazole and 1 part of 1-cyanoethyl-2-ethyl- 8 parts of 4-methylimidazole and 10 parts of a photopolymerization initiator (Irgacure 651 manufactured by Ciba Geigy) were added, and sufficiently stirred with a homomixer to obtain an undercoat agent.
Further, a flame-retardant glass epoxy double-sided copper-clad laminate having a base material thickness of 0.2 mm and a copper foil thickness of 35 μm was patterned to obtain an inner circuit board. After the surface of the copper foil was blackened, the undercoat agent was applied to one surface of the inner circuit board to a thickness of about 40 μm using a curtain coater. Then, UV irradiation was performed using a UV conveyer machine with two 80 W / cm high-pressure mercury lamps under the condition of about 2 J / cm ² , and a tack-free undercoat layer was formed by irradiation with active energy rays. An undercoat layer was similarly prepared on the surface. Thereafter, the inner circuit board on which the undercoat layer was formed was passed through an infrared heater furnace at a set temperature of 80 ° C. for about 1 minute, and the surface temperature of the inner circuit board was heated to 60 ° C.
With the surface temperature maintained, a temperature of 100 ° C., a pressure of 2 kg / cm ² , and a laminating speed of 1.0 were applied on the undercoat layer.
The copper foil with the interlayer insulating adhesive was laminated using two rolls under the condition of m / min, and heated and cured at 150 ° C. for 30 minutes to produce a multilayer printed wiring board.

Example 2 The laminating speed was 3.0.
A multilayer printed wiring board was produced in the same manner as in Example 1 except that the speed was changed to m / min. << Comparative Example 1 >> A multilayer printed wiring board was produced in exactly the same manner as in Example 1 except that the heat treatment of the inner layer circuit board before lamination was omitted. << Comparative Example 2 >> A multilayer printed wiring board was produced in exactly the same manner as in Example 2 except that the heat treatment of the inner layer circuit board before lamination was omitted. The obtained multilayer printed wiring board has characteristics as shown in Table 1.

<< Test Method >> ・ Inner circuit board test piece: 150 μm pitch between lines, 2.54 mmφ clearance hole 1. Surface smoothness: JIS B 0601 R (max) 1. Moisture absorption heat resistance test Moisture absorption conditions: pressure cooker treatment, 125 ° C,
Test conditions: 3 atm, 30 minutes Test conditions: n = 5, all were 280 ° C., 120 seconds No swelling was evaluated as ○, and swelled was evaluated as x. 3. Embedding property: After peeling the outer layer copper foil, the embedding property in the inner layer circuit was visually determined using an optical microscope. A sample that was completely embedded was evaluated as ○, and a sample that was incompletely embedded was evaluated as ×. 4. Interlayer insulation layer thickness: The multilayer printed wiring board was cut, and its cross section was observed with an optical microscope to measure the thickness of the interlayer insulation layer between the inner layer circuit and the surface copper foil. 5. Remaining molded voids: The entire surface of the multilayer printed wiring board was etched, and the presence or absence of voids was visually measured. A sample without voids was evaluated as ○, a sample with slight voids was evaluated as Δ, and a sample with completely voids was evaluated as ×.

[0028]

[0029]

According to the method of the present invention, by laminating a copper foil with a thermosetting insulating adhesive with a hot roll or the like, the photocured undercoat agent applied to the inner layer circuit is softened and the surface is smoothened. Since the thermosetting insulating adhesive coated on the copper foil maintains its thickness, it is possible to produce a multilayer printed wiring board with excellent thickness control without depending on the residual rate of the inner copper foil. The obtained multilayer printed wiring board has good heat resistance and excellent flame retardancy. The manufacture of a multilayer printed wiring board has become extremely easy.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a step of manufacturing a multilayer printed wiring board (one example) of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 inner layer circuit board 2 inner layer circuit 3 undercoat agent 4 interlayer insulating adhesive 5 copper foil 6 hard roll 7 multilayer printed wiring board

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI C09J 163/02 C09J 163/02 (72) Inventor Masataka Arai 2-5-8 Higashishinagawa, Shinagawa-ku, Tokyo Sumitomo Bakelite Co., Ltd.

Claims (3)

[Claims] 1. An inner layer circuit board comprising a glass cloth substrate impregnated with a flame-retardant epoxy resin, coated with a light / thermosetting undercoat agent, and made tack-free by irradiating with active energy rays. A method for producing a multilayer printed wiring board, comprising: laminating a copper foil having a layer, and then integrally curing by heating, wherein when the copper foil having an interlayer insulating adhesive layer is roll-laminated, a light / thermosetting undercoat agent is used. Pre-heats the inner layer circuit board after coating and tack-free, and then, at the time of roll lamination, it is possible to bond the interlayer insulating adhesive layer to a temperature at which the light / thermosetting undercoat agent can be softened by the heated roll. A method for producing a multilayer printed wiring board, characterized in that the temperature reaches a specific temperature. 2. The temperature at the time of roll lamination of an adhesive portion between an undercoat agent and an interlayer insulating adhesive layer is 70 to 110.
The method for producing a multilayer printed wiring board according to claim 1, wherein the temperature is ° C. 3. The light / thermosetting undercoat agent is:
(A) a bromination ratio of 20% or more and a molecular weight of 500 to 4000;
Novolak type epoxy resin, (b) bisphenol type epoxy resin having a molecular weight of 500 or less, (c) hydroxyethyl acrylate or hydroxyethyl methacrylate, (d) polyfunctional acrylate monomer or polyfunctional methacrylate monomer (e) photopolymerization initiator, F) an imidazole compound having a melting point of 130 ° C. or more, and (g) a low-temperature-curable imidazole compound,
(H) bromination ratio 20% or more and weight average molecular weight 1000
0 or more brominated bisphenol type epoxy resin or brominated phenoxy resin, (ii) a bisphenol type epoxy resin having an epoxy equivalent of 500 or less, and (u) a melting point of 130
The method for producing a multilayer printed wiring board according to claim 1, wherein the method comprises an imidazole compound having a temperature of not lower than ℃.