JPH0878853A - Manufacture of multilayered printed wiring board - Google Patents

Abstract

PURPOSE: To improve the productivity of a printed wiring board, and reduce the formation time, by stacking fast-curing prepreg containing specific compound on both sides of a circuit-worked double-sided copper clad lamination board, and performing lamination-pressing. CONSTITUTION: Thermosetting type or photo-setting type or photo-thermosetting type undercoat material is spread on both surfaces of an inner layer circuit board, and copper foil step-difference of the inner layer circuit is eliminated or reduced. On both surfaces, fast-curing prepreg is stacked and lamination- pressed which material contains the following; epoxy resin containing two or more epoxy groups in a molecule, polyfunctional phenol, dicyandiamine and guanido compound. The equivalent ratio of the epoxy resin compound for 1 equivalent of epoxy resin having two or more epoxy groups in a molecule is polyfunctional phenol 0.5-1.2 equivalent, dicyandiamine 0.02-0.4 equivalent, and guanido compound 0.03-0.5 equivalent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer printed wiring board in which the time required for molding is shortened.

[0002]

2. Description of the Related Art As a conventional manufacturing method of a multilayer printed wiring board, generally, both sides of a circuit-processed double-sided copper clad laminate (hereinafter referred to as an inner layer circuit board) to be laminated on an inner layer are formed. One or more prepregs obtained by coating, impregnating, and drying a thermosetting resin on a substrate were directly laminated, and a metal foil was further laminated on the upper surface of the prepreg, which was then pressed by a heated heating plate for a long time. Further, as a method for manufacturing a multilayer printed wiring board in which a resin layer is formed on the circuit surface of an inner layer circuit board, there are disclosed in Japanese Patent Laid-Open Nos. 53-132772 and 60-62.
194, Japanese Patent Laid-Open No. 63-108796, Japanese Patent Publication No. 3
In each of the technologies, the goal is to improve the withstand voltage property, the halo resistance, the heat dissipation property, and the insulating layer thickness by reducing voids during molding. Was to be.

[0003]

However, such conventional methods are not aimed at improving productivity and shortening molding time, and no effect on them has been recognized. As described above, it is an object of the present invention to improve the productivity of a multilayer printed wiring board, which cannot be achieved by the prior art.
The present inventors have conducted intensive studies on the problem of moldability of a multilayer printed wiring board and a resin composition contained in a prepreg for imparting a rapid curing property, and as a result, have achieved the present invention.

[0004]

The present invention provides a method for producing a multilayer printed wiring board in which a thermosetting resin is impregnated into a base material on both sides of an inner layer circuit board and dried prepregs are laminated and pressed. After applying a thermosetting, photocurable or photothermal combined undercoating agent to both sides of the inner layer circuit board to eliminate or reduce the step of the copper foil of the inner layer circuit, (a) epoxy is applied to both sides. A rapid-curing prepreg containing an epoxy resin having two or more groups in one molecule, (b) a polyfunctional phenol, (c) a dicyandiamine, and (d) a guanide compound is overlaid and laminated and pressed. And a method for manufacturing a multilayer printed wiring board.

Reference will be made to the composition of the undercoat agent. As the thermosetting type, a resin which is liquid at room temperature or a solid resin containing an epoxy resin and an aromatic amine as main components and which is liquefied by dissolving in a solvent, likewise an epoxy resin and a polyfunctional novolac as main components. Examples of the resin include a resin, an epoxy resin and a resin containing dicyandiamide as a main component, and a resin containing bismaleimide as a main component. Examples of the photocurable resin include a photosensitizer, an unsaturated polyester resin containing a photoinitiator, an acrylate resin, and a methacrylate resin. Also, as a combination of light and heat, epoxy resin to glycidyl methacrylate that is liquid at room temperature,
Examples thereof include resins in which polyfunctional novolac is dissolved. These should be selected in consideration of adhesion with copper foil, heat resistance, moisture resistance, affinity with prepreg, etc., but are thermosetting, photocurable or photothermal combined undercoat agents. If there is, it is not particularly limited.

As a method for applying the above-mentioned undercoat agent, there are methods such as a roll coater, a curtain coater, a casting method, a spinner coater, a dip coater and screen printing, and any of these methods can be applied.

The cured state of the undercoat agent will be mentioned. Generally, the cured state can be divided into an A stage state which is a completely uncured state, a B stage state which is a semi-cured state, a gel state in which further curing is promoted, and a C stage state which is a completely cured state. However, any state may be used.

Next, the composition of the prepreg will be described. An important point of the present invention is that the recesses between the inner layer circuits are previously filled with the undercoating agent so that there is no step difference in the inner layer copper foil or it is significantly reduced. Is completely unnecessary. Therefore, the curability of the prepreg can be set as fast as possible in consideration of other characteristics, and the productivity can be improved. Therefore, by making the epoxy resin with which the prepreg is impregnated to have the composition shown below, it is possible to further improve the productivity, which is the object of the present invention.

That is, the epoxy resin composition is (a)
Epoxy resin having two or more epoxy groups in one molecule,
It is characterized by containing (b) a polyfunctional phenol, (c) dicyandiamine, and (d) a guanide compound, and it is particularly remarkable that the curing speed from the B stage state, which is the curing state of the prepreg, to the final curing is fast. It is mentioned as a characteristic.

As the epoxy resin, any epoxy resin having two or more epoxy groups conventionally used for electrical insulation can be used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin. , Phenol novolac type epoxy resin, orthocresol novolac type epoxy resin, isocyanurate type epoxy resin, or trifunctional or tetrafunctional glycidylamine type epoxy resin, biphenyl skeleton epoxy resin, naphthalene skeleton epoxy resin, cyclo Examples thereof include an epoxy resin having a pentadiene skeleton and an epoxy resin having a limonene skeleton. Further, their bromides and the like are also used. These may be used alone or in combination of several kinds.

For polyfunctional phenols, 1 in the molecule
Phenol having 1 phenolic hydroxyl group, or polyfunctional phenol obtained by condensing an alkyl derivative thereof with formaldehyde under acidic catalyst and 2 in the molecule
A polyfunctional phenol obtained by condensing a phenol compound having individual hydroxyl groups with formaldehyde under an acidic catalyst is applicable. As the former, phenol novolac, o
-Cresol novolac, p-cresol novolac,
Examples thereof include pt-butylphenol novolac, hydroxynaphthalene novolac, dihydroxynaphthalene novolac, and the latter include bisphenol A novolac, bisphenol F novolac, and terpene-modified novolac (YLH-40 manufactured by Yuka Shell Epoxy Co., Ltd.).
2) is exemplified. In addition, dicyclopentadiene modified phenol novolac (DC-manufactured by Sanyo Kokusaku Pulp Co., Ltd.)
100LL), para-xylene modified phenol novolak (XL-225LL manufactured by Mitsui Toatsu Co., Ltd.), polybutadiene modified phenol novolak (PP-manufactured by Nippon Oil Co., Ltd.).
700) and the like are exemplified.

Dicyandiamide is added to impart good adhesion to the copper foil. The guanide compound generally refers to a compound having a guanidine structure, and includes 1,3-diphenylguanidine, di-orthotolylguanidine, 1-orthotolyldiguanide, α-2,5-dimethylguanide, α, ω-diphenyldigine. Anide, 5-hydroxynaphthyl-1-diguanide, phenyldiguanide, α, α′-bisguanylguanididinodiphenyl ether, p-chlorophenyldiguanide, α-benzyldiguanide, α, ω-dimethyldiguanide De, α, α'-
Hexamethylenebis [ω- (p-chlorophenol)]
Diguanide, o-tolyldiguanide zinc salt, diphenyldiguanide iron salt, phenyldiguanide copper salt, diguanide nickel salt, ethylenebisdiguanide hydrochloride, lauryldiguanide hydrochloride, phenyldiguanide oxalate,
Examples thereof include mono-substituted or di-substituted alkyl-modified phenyldiguanide and the like.

The advantage of these guanide compounds is that they generate a great amount of heat when they react with an epoxy group to open the epoxy ring. Therefore, the reaction is remarkably accelerated in the reaction system in which the addition polymerization is caused with the epoxy resin by heating. When the reaction of the epoxy resin was examined by a scanning calorimeter, the prepreg in the system in which no guanide compound was present, for example, FR-4 prepreg having an epoxy resin, an aromatic polyamine and dicyandiamide as a composition, had a resin content of 1 m.
20-40 mJ per gram, the amount of heat generated during the reaction is small, the reaction initiation temperature is about 150 ° C, and the reaction activation temperature is about 1
As high as 70 ° C. That is, it is suggested that the reaction is difficult to proceed in the temperature rising process at the time of press molding, and that a larger amount of heat needs to be supplied until complete curing. On the other hand, in the system of epoxy resin, polyfunctional phenol, dicyandiamide, guanide compound, 60 to 60
The amount of heat generated during the reaction was as high as 140 mJ, the reaction initiation temperature was about 130 ° C, and the reaction activation temperature was about 150 ° C.
That is, it is suggested that the curing reaction occurs at a lower temperature in the temperature rising process during press molding, the reaction is further promoted by heat generation, and the curing reaction ends in a short time.

The blending amount will be mentioned. The blending amount of the polyfunctional phenol is determined in relation to the glass transition temperature. That is, when the compounding amount is less than 0.5 equivalent with respect to 1 equivalent of the epoxy resin, the glass transition temperature is low and the effect of adding the polyfunctional phenol is not sufficiently observed. When the amount added is further increased, the glass transition temperature is almost the highest at 1.0 equivalent, and the glass transition temperature level does not change up to 1.2 equivalent. When the amount is further increased, the glass transition temperature gradually begins to decrease. Therefore, it is considered to be suitable to mix in the range of 0.5 to 1.2 equivalents. The blending amount of dicyandiamide is determined in consideration of the adhesiveness to the copper foil and the solder heat resistance when absorbing moisture. That is, 0.
If the blending amount is less than 02 equivalents, the addition effect is small from the viewpoint of improving the adhesiveness to the copper foil, and the O. When the compounding amount exceeds 4 equivalents, the amount of moisture absorption increases, which easily causes the deterioration of solder heat resistance after moisture absorption treatment, which is also an advantage of the polyfunctional phenol, and also causes the deterioration of storage stability. Regarding the compounding amount of the guanide compound, when the equivalent amount is calculated assuming that all the amines contained in one molecule of the guanide compound participate in the crosslinking reaction, when the amount is 0.03 equivalent or less, the calorific value is small and the curing rate is sufficiently fast. However, when the amount exceeds 0.5 equivalent, the amount of moisture absorption becomes large, and the solder heat resistance tends to be lowered like dicyandiamide. Therefore, it is desirable that the content is 0.03 to 0.5 equivalent.

There are no particular restrictions on the composition other than these. For example, in order to improve the adhesion with glass cloth, epoxysilane, addition of a coupling agent exemplified by aminosilane, or for the purpose of further improving the plate thickness accuracy, polybutadiene rubber-based, nitrile-based rubber, nitrile-butadiene rubber, Further, it is possible to add a carboxylic acid-modified rubber, an amine-modified rubber or the like. In addition, there is no particular limitation on the addition of imidazole, adductimidazole, a microencapsulation curing accelerator, a phosphine-based accelerator, and an amine-based accelerator in order to adjust the gel time of the prepreg and to impart further rapid curing property.

[0016]

By using the thermosetting, photocurable or photothermal combined undercoating agent of the present invention, an undercoat layer is formed on the upper surface of the inner layer circuit board, so that the recesses between the circuits are previously filled with resin. Therefore, even if the prepregs are superposed and laminated, the prepregs can be molded without any unfilled defect. Therefore, although the resin amount of the prepreg and the fluidity at the time of heating have been conventionally changed by the copper foil remaining rate of the inner layer circuit, this is no longer necessary. That is, since the plate thickness accuracy does not depend on the copper foil residual rate of the inner layer circuit, it is possible to support with a few types of prepregs, and thus it is possible to manufacture a large number of prepregs in a small variety. It was Further, the time required to fill the concave portion (etching portion) of the inner layer circuit of the prepreg is completely unnecessary, and by using the fast-curing prepreg, it takes about 120 to 200 minutes in the conventional one-time lamination molding. It has become possible to reduce the molding time that had been required to about 20 minutes. As a result, manufacturing costs are significantly reduced,
The man-hours for quality control and inventory control will also be greatly reduced.

In addition, an unexpected effect at first,
In the multilayer printed wiring board obtained by the method for producing a multilayer printed wiring board of the present invention, as compared with the conventional production method, the resin flow is small, so that the plate thickness accuracy is good and the undercoating agent Due to the embedding effect, the surface smoothness of the outer layer surface is high, and it is possible to form a fine pattern circuit.

[0018]

EXAMPLES The present invention will be described in detail below based on examples.

Example 1 60 parts by weight of a bisphenol A type epoxy resin (epoxy equivalent: 900) and 40 parts by weight of a bisphenol A type epoxy resin (epoxy equivalent: 190) were dissolved in 50 parts by weight of ethylcarbitol, and 10 parts by weight of dicyandiamide. After adding 0.5 parts by weight of 2-ethyl-4-methylimidazole and 20 parts by weight of talc, kneading with a three-roll mill, defoaming was performed for 5 minutes at a vacuum degree of 3 mmHg with a vacuum defoamer, and heat was applied. A curable epoxy resin undercoat agent was obtained.

Next, the substrate thickness is 0.1 mm and the copper foil thickness is 35 μm.
The glass epoxy double-sided copper-clad laminate of No. 2 was processed into a circuit to produce an inner layer circuit board. Then, an oxidation treatment generally called black treatment is applied to roughen the circuit surface, and the thermosetting epoxy resin undercoating agent is screen-printed on one surface thereof, and then heated in a dryer at 130 ° C. for 2 minutes. After that, the undercoat agent was applied to the back surface in the same manner and dried. The coating thickness of the undercoating agent was measured with a contact-type thickness meter, and it was 7 μm at the inner layer circuit forming portion and 30 μm at the inner etching portion of the inner layer circuit.
Met. Therefore, when the thickness of the copper foil was measured, it was 3
Since it was 4 μm, the step was found to be 11 μm.

Further, an epoxy resin having a composition ratio shown in Table 1,
A base material is impregnated with an epoxy resin composition composed of polyfunctional phenol, dicyandiamide, and 1-orthotolyldiguanide, and dried to obtain a prepreg (180 μm thick, resin content 42%). One sheet is laminated on each side of the inner layer circuit board coated with the undercoat material, and one copper foil with a thickness of 18 μm is laminated on the upper surface of the inner layer circuit board.
Molding was performed by a vacuum press at a maximum temperature of 170 ° C./° C./min. The time required to reach the maximum temperature was about 10 minutes.

Regarding the heating time required for molding, the relationship between the press heating time and the glass transition temperature was investigated, and the glass transition temperature (± 3 ° C.) was almost equal to the glass transition temperature of the prepreg at 140 minutes of heating time. The heating time required was the heating time required for molding. Therefore, the heating time required for molding is the sum of the temperature rising time from room temperature to the highest temperature and the holding time at the highest temperature. The viscoelastic method was used for the glass transition temperature. The glass transition temperature of the inner layer circuit board is 15
It is 0 ± 2 ° C., and the glass transition temperature of the prepreg and the glass transition temperature of the inner layer circuit board can be separated by peak separation by the viscoelastic method. As a result, the heating time required for molding was 20 minutes, and Table 1 shows the characteristics as a laminate during the heating time.

Here, regarding the preservability of the prepreg,
The prepreg was stored in a temperature / humidity atmosphere of 25 ° C. and 60%, and molded every two weeks under the above-mentioned molding conditions, and the etching appearance was compared with the initial appearance and judged. When the life of the prepreg has passed, voids will remain, so it is possible to make a sufficient judgment by checking the appearance as a simple method.

Example 2 30 parts by weight of propoxytrimethylolpropane triacrylate was added to 70 parts by weight of phenol novolac methacrylate and dissolved, and then 5 parts by weight of Irgacure 651 manufactured by Ciba-Geigy Co., Ltd.,
3 parts by weight of N, N′-dimethylaminoethyl methacrylate, 0.1 part by weight of p-methoxyphenol, and 2 parts by weight of R-805 manufactured by Nippon Aerosil Co., Ltd. as a thixotropic agent were added, and mixed by stirring, followed by vacuum desorption. Defoaming was performed for 5 minutes at a vacuum degree of 3 mmHg by using a bubbler to obtain a photocurable epoxy resin undercoat agent.

The above photocurable undercoat agent was applied to one surface of an inner layer circuit board prepared in the same manner as in Example 1 by a casting method, and then cured in a UV curing furnace. Similarly, an undercoating agent was applied to the back surface and cured. When the coating thickness of the undercoat agent was measured with a contact type thickness meter, it was 3 μm at the inner layer circuit forming portion and 34 μm at the inner etching portion of the inner layer circuit. Therefore, when the thickness of the copper foil was measured and found to be 34 μm, it was found that the step was 3 μm.

Further, an epoxy resin having a composition ratio shown in Table 1,
A prepreg (180 μm thick, obtained by impregnating a base material with an epoxy resin composition composed of polyfunctional phenol, dicyandiamide and p-chlorophenyldiguanide, and drying the same.
Resin content 42%) is laminated one by one on both sides of the inner layer circuit board coated with the above undercoat material, and one copper foil with a thickness of 18 μm is laminated on the upper surface thereof, and heating is started from room temperature, and the heating rate is increased. 18 ℃ / min, maximum temperature reached 170 ℃
It was molded by a vacuum press. As a result, the heating time required for molding was 20 minutes, and Table 1 shows the characteristics of the laminated plate during the heating time.

(Example 3) Glycidyl methacrylate 3
30 parts by weight of bisphenol A type epoxy resin (Epicoat 1004 manufactured by Yuka Shell Epoxy Co., Ltd.) in 0 parts by weight,
Brominated novolac type epoxy resin (B manufactured by Nippon Kayaku Co., Ltd.
40 parts by weight of REN-S) was added and dissolved, then 2 parts by weight of Irgacure 651 manufactured by Ciba-Geigy Co., Ltd., 5 parts by weight of o-tolyldiguanide, 1 part by weight of 2- (dimethylamino) ethyl methacrylate, Nippon Aerosil Co., Ltd. ) Made R
After adding -8051 parts by weight and stirring and mixing, defoaming was performed for 5 minutes at a vacuum degree of 3 mmHg by a vacuum defoaming device to obtain an epoxy resin undercoating agent for combined use with light and heat.

The above-mentioned photocurable undercoating agent was applied to one surface of an inner layer circuit board prepared in the same manner as in Example 1 by a casting method, and then cured in a UV curing furnace. Similarly, an undercoating agent was applied to the back surface and cured. When the coating thickness of the undercoat agent was measured with a contact type thickness meter, it was 3 μm at the inner layer circuit forming portion and 34 μm at the inner etching portion of the inner layer circuit. Therefore, when the thickness of the copper foil was measured and found to be 34 μm, it was found that the step was 3 μm.

Further, an epoxy resin having a composition ratio shown in Table 1,
A base material impregnated with an epoxy resin composition composed of polyfunctional phenol, dicyandiamide and phenyldiguanide and dried to obtain a prepreg (180 μm thick, resin content 4
2%) is laminated on both sides of the inner layer circuit board coated with the above-mentioned dried photocurable resin undercoat material, and a copper foil having a thickness of 18 μm is laminated on the upper surface thereof and heated from room temperature. Then, molding was performed by a vacuum press at a temperature rising rate of 18 ° C./min and a maximum reached temperature of 170 ° C. As a result, the heating time required for molding was 20 minutes, and Table 1 shows the characteristics of the laminated plate during the heating time.

Comparative Example 1 Base material thickness 0.1 mm, copper foil thickness 3
Circuit processing of 5μm glass epoxy double-sided copper clad laminate,
The inner layer circuit was created. Then, an oxidation treatment generally called black treatment was applied to roughen the circuit surface to produce an inner layer circuit board. Next, a conventional FR-4 prepreg (180 μm thick, resin content 50%) obtained by impregnating a base material with an epoxy resin composition composed only of an epoxy resin, a polyfunctional phenol and dicyandiamide, and drying it was prepared as described above. One sheet is laminated on each side of the inner layer circuit board, one sheet of copper foil with a thickness of 18 μm is laminated on the upper surface, heating is started from room temperature, heating rate is 2.7 ° C./min, maximum attainable temperature is 170 ° C.
It was molded by a vacuum press. The time required to reach the maximum temperature was about 60 minutes. This is because the prepreg needs a sufficient time to fill the recesses between the inner layer circuits, and therefore the temperature rising speed of the material needs to be sufficiently slowed. Further, when the heating time required for molding was examined in the same manner as in Example 1, it was found that heating for about 120 minutes was necessary. The laminated plate characteristics are shown in Table 1.

(Comparative Example 2) The undercoating agent prepared in Example 1 was applied to the inner layer circuit and dried in exactly the same manner as in Example 1. Next, epoxy resin,
Ordinary FR-4 prepreg (180 μm thick, resin component 4 was obtained by impregnating a base material with an epoxy resin composition composed only of polyfunctional phenol and dicyandiamide and drying the composition.
2%) is laminated on both sides of the above inner layer circuit board one by one, and one copper foil having a thickness of 18 μm is laminated on the upper surface thereof, and heating is started from room temperature, the temperature rising rate is 18 ° C./min, and the maximum reached temperature is reached. Molding was performed by a vacuum press at 170 ° C. It took about 10 minutes to reach the maximum temperature,
It was found that the heating time required for molding was about 60 minutes. The laminated plate characteristics are shown in Table 1.

[0032]

[Table 1]

[0033]

As described above, in order to eliminate or reduce the step difference of the copper foil of the inner layer circuit by previously applying the thermosetting type, photocuring type or photothermal combination type undercoating agent on both surfaces of the inner layer circuit board. By combining with a fast-curing prepreg, it has become possible to achieve high productivity three to four times that of the conventional product. At the same time, it is not necessary to change the resin content, gel time, etc. of the prepreg depending on the residual copper foil rate of the inner layer circuit, so that the types of prepreg are greatly reduced.
In addition, it will open the way to the automation of the prepreg set that is currently performed by a huge amount of manpower.

Claims (2)

[Claims] 1. A method for producing a multilayer printed wiring board, comprising laminating and pressing a prepreg obtained by impregnating a base material with a thermosetting resin on both sides of a circuit-processed double-sided copper-clad laminate, and laminating and pressing the prepreg. On both sides of the processed double-sided copper clad laminate, a thermosetting type, a photocuring type or a photothermal combination type undercoating agent is applied to eliminate or reduce the step of the copper foil of the inner layer circuit, and then to both sides, (A) Epoxy resin having two or more epoxy groups in one molecule, (b) polyfunctional phenol, (c) dicyandiamine, and (d)
A method for producing a multilayer printed wiring board, characterized in that a rapid-curing prepreg containing a guanide compound is superposed and laminated and pressed. 2. The epoxy resin composition contained in the prepreg has an equivalent ratio of (a) to one equivalent of an epoxy resin having two or more epoxy groups in one molecule,
The multilayer print according to claim 1, wherein (b) polyfunctional phenol is 0.5 to 1.2 equivalents, (c) dicyandiamide is 0.02 to 0.4 equivalents, and (d) guanide compound is 0.03 to 0.5 equivalents. Wiring board manufacturing method.