JPH0832243A - Production of multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To achieve high moldability without generating any void by applying a thermosetting undercoat agent to the opposite sides of a double side copper clad laminate formed with a circuit and then laminating a prepreg containing a specified resin compound to the opposite sides. CONSTITUTION:A thermosetting undercoat agent is applied to the opposite sides of a double side copper clad laminate formed with a circuit. It is then laminated, on the opposite sides with a prepreg containing a resin composition comprising an epoxy resin having more than one epoxy group in one molecule, an aromatic diamine, dicyandiamide, and a guanido compound having aromatic ring structure before being pressed. Since a thermosetting undercoat agent is previously applied and dried, bubble can be eliminated perfectly and high moldability is achieved without generating any void. Furthermore, since the residual copper foil rate in the inner layer circuit eliminates the need of changing the kind of prepreg, the kind of prepreg can be decreased.

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 which shortens the manufacturing time.

[0002]

2. Description of the Related Art As a conventional manufacturing method of a multilayer printed wiring board, a circuit-processed double-sided copper clad laminate (inner layer material)
One or more prepregs in which a base material is impregnated with a thermosetting resin and dried are directly stacked on both sides of the above, and a metal foil is further stacked on the upper surface, and laminated pressing is performed for a long time by a heated hot platen. Met.

[0003]

In this case, first, since the circuit is formed on the surface of the inner layer material, in order to sufficiently remove the bubbles existing in the recesses between the circuits, the melting time of the resin in the prepreg is set. It is necessary to make the length longer and to keep the pressure reduced for a long time by a vacuum press. Also, since the plate thickness of the molded product greatly depends on the copper foil residual rate of the inner layer material, in order to control the plate thickness accuracy, prepare a great many types of prepregs with different resin amounts, melting times, etc. This is necessary, which increases man-hours in terms of manufacturing, quality control, raw materials, and product distribution, which is a factor of cost increase.

In the present invention, a thermosetting undercoating agent is applied in advance on both sides of a circuit-processed double-sided copper-clad laminate, dried or semi-cured, and then a prepreg and a metal foil are superposed and laminated and pressed. It is related to the improvement of technology, and there are no bubbles existing in the recesses between the circuits, and it is possible to obtain good formability without generating voids without applying pressure for a long time using a vacuum press as in the past. You can In addition, since it is possible to shorten the curing time of the prepreg in terms of formability, it is possible to significantly reduce the manufacturing time of the multilayer printed wiring board. Furthermore, since the undercoating agent is applied to the surface of the inner layer circuit in advance, it becomes possible to control the plate thickness accuracy without being affected by the copper foil residual rate, and as a result, the type of prepreg used can be reduced. . The production of prepregs will be a large quantity and a small number of products, which will reduce the manufacturing cost and the man-hours for quality control and inventory control.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a multi-layer printed wiring in which a circuit-processed double-sided copper-clad laminate is laminated on both sides with a prepreg which is a base material impregnated with a thermosetting resin and dried, and laminated and pressed. In the method for producing a plate, a thermosetting undercoating agent is applied to both surfaces of the circuit-processed double-sided copper-clad laminate, and (a) two or more epoxy groups are contained in one molecule on the both surfaces. Epoxy resin (b) Aromatic diamine (c) Dicyandiamide (d) A method for producing a multilayer printed wiring board in which a prepreg containing a resin composition comprising a guanide compound having an aromatic ring skeleton is laminated and pressed.

As a method for applying the thermosetting undercoating agent, there are methods such as a roll coater, a curtain coater, a casting method, a spinner coater, and a screen printing, and any method is possible. 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, it may be in any state. In terms of the composition of the thermosetting undercoat agent, it should be selected in consideration of adhesiveness with copper foil, heat resistance, moisture resistance, compatibility with prepreg, etc., but is not particularly limited.

Next, the composition of the prepreg will be described. As described in detail in the section "Problems to be solved by the invention", the important point of the present invention is that the thermosetting undercoat agent pre-fills the concave portion of the inner layer circuit, and therefore is required for the conventional prepreg. That is, the embedding function that was said to be 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. In that sense, by using a fast-curing type epoxy resin composition instead of the conventional prepreg, a great effect is exerted on the productivity improvement which is the object of the present invention.

The epoxy resin composition comprises (a) an epoxy resin having two or more epoxy groups in one molecule, (b) an aromatic diamine, (c) dicyandiamide, and (d) a guanidine compound having an aromatic ring skeleton. A characteristic is that the curing speed from the B stage state, which is the curing state of the prepreg, to the final curing is particularly high.

As the epoxy resin, any epoxy resin having two or more epoxy groups, which has been 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. Resin, phenol novolac type epoxy resin, orthocresol novolac type epoxy resin,
Isocyanurate type epoxy resin, trifunctional or tetrafunctional glycidylamine type epoxy resin, epoxy resin having biphenyl skeleton, epoxy resin having naphthalene skeleton, epoxy resin having cyclopentadiene skeleton, epoxy having limonene skeleton Resin etc. are mentioned. Further, their bromides and the like are also exemplified. These may be used alone or in combination of several kinds.

Regarding the aromatic diamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, metaphenylenediamine, or 4,4 '
Examples thereof include alkyl-modified aromatic amines such as -diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane. Regarding the blending amount of these, the larger the amount, the more the heat resistance is improved, but the blending amount must be determined in consideration of the storability of the prepreg. Therefore, if the compounding amount is less than 0.1 equivalent relative to 1 equivalent of the epoxy resin, the effect of adding the aromatic diamine for improving the heat resistance is not noticeable, and if the compounding amount exceeds 0.8 equivalent. If done, it is difficult to satisfy the usual market requirement of 3 months of shelf life. Furthermore, when the halogen-containing aromatic amine according to claim 3 is used as the aromatic diamine, 1.5 to 3 times the preservability is obtained at the same compounding amount as compared with the case of using the other aromatic diamine. Shown and still desirable for this application.

Dicyandiamide is added to impart good adhesion to the copper foil. The blending amount is determined in consideration of heat resistance, heat resistance during moisture absorption, and the like. That is,
When the amount is less than 0.1 equivalent, it is difficult to obtain sufficient copper foil adhesion, and when the amount is more than 0.8 equivalent, the amount of moisture absorption increases and the moisture absorption after the moisture absorption treatment is increased. It is likely to cause deterioration of solder heat resistance.

The guanidine compound is a general term for compounds having a guanidine structure represented by the following chemical formula,
As a guanidine compound having an aromatic ring skeleton, 1,3-diphenylguanidine, diorsotolylguanidine, 1
-Orthotolyldiguanide, and further 1- or 2-substituted alkyl-modified phenyldiguanide and the like are exemplified.

[0013]

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In the present invention, the feature of these compounds is that they react with an epoxy group and generate a very large amount of heat when the epoxy ring is opened. As a result, the reaction between the epoxy resin, which is mainly addition-polymerized by heat, and the aromatic diamine or dicyandiamide is significantly accelerated. When the reaction of epoxy resin, aromatic diamine, and dicyandiamide was examined with a scanning calorimeter, the calorific value was small and the reaction peak was broad or separated into two in the system in which no guanidine compound having an aromatic skeleton was present. However, it was found that in a system in which a guanidine compound having an aromatic skeleton is present, the reaction has one peak and is sharp, and the calorific value is large. Regarding the blending amount, the equivalent amount was calculated on the assumption that all the amino groups contained in one molecule of the guanidine compound are reacted, but if the amount is less than 0.1 equivalent, the calorific value is small and sufficient rapid curability cannot be obtained, so that the amount is less than 0.1. When the amount is more than 6 equivalents, the amount of moisture absorption becomes large as in the case of dicyandiamide, and the solder heat resistance tends to deteriorate.

There are no particular restrictions on the composition added other than these. For example, in order to improve the adhesion with glass cloth, addition of a coupling agent exemplified by epoxysilane and aminosilane, or for the purpose of further improving the plate thickness accuracy, polybutadiene rubber, nitrile 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 restriction on the addition of imidazole, adductimidazole, a microencapsulation curing accelerator, a phosphine-based amine accelerator, or an amine-based accelerator for adjusting the gel time of the prepreg or imparting further rapid curing property.

[0016]

By using the thermosetting undercoating agent of the present invention, an undercoat layer is formed on the upper surface of a double-sided copper clad laminate having a circuit processed. Therefore, the recesses between the circuits must be filled with resin in advance. Therefore, even if the prepregs are superposed and laminated, they can be molded without leaving air bubbles. Therefore, conventionally, the resin amount of the prepreg and the fluidity at the time of heating were changed depending on the copper foil remaining rate of the inner layer circuit, but 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 cope with a few kinds of prepregs, so that it is possible to manufacture a large number of prepregs in a small variety. .

Furthermore, since the time required to fill the recesses between the inner layer circuits of the prepreg is completely eliminated, the time required for the press, which conventionally took 120 minutes or more, can be reduced to about 60 minutes at most. It becomes possible to
By using the prepreg having the epoxy resin composition described in claim 1, it is possible to further shorten the time to about 20 minutes. As a result, manufacturing costs are significantly reduced, and man-hours spent for quality control and inventory control are also significantly reduced.

[0018]

EXAMPLES The present invention will now be described in detail 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 to give 10 parts by weight of dicyandiamide. 2-Ethyl-4-methylimidazole 0.
After adding 5 parts by weight and 20 parts by weight of talc, the mixture was kneaded with a three-roll mill, and was mixed with a vacuum defoamer at a vacuum degree of 3 mmHg to 5
Degassing was performed for a minute to obtain a thermosetting epoxy resin undercoat agent.

Next, the substrate thickness is 0.1 mm and the copper foil thickness is 35 μm.
The glass epoxy double-sided copper clad laminate was processed to form an inner layer circuit. 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 of the circuit, followed by heating and drying in a dryer at 150 ° C for 2 minutes. After that, an 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 34μ.
Since it was m, the step was found to be 11 μm.

Further, an epoxy resin having a composition ratio shown in Table 1,
A prepreg composed of aromatic diamine, dicyandiamide and 1-orthotolyldiguanide (180 μm
Thickness, resin content 42%) is laminated on both sides of the inner layer material coated with the dried thermosetting resin undercoat material, and a copper foil having a thickness of 18 μm is laminated on the upper surface thereof. Start heating from room temperature, heating rate 18 ℃ /
Molding was performed by a vacuum press at a maximum attainable temperature of 170 ° C. 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
The heating time required to reach (° C.) was defined as 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 material is 150 ± 2 ° C.,
By viscoelastic method, it is possible to separate the glass transition temperature of the prepreg and the glass transition temperature of the inner layer material by peak separation. As a result, the heating time required for molding was 20 minutes, and the characteristics of the laminated plate during the heating time are shown in Table 1.
Name it.

Here, regarding the preservability of the prepreg,
The prepreg was stored in a temperature / humidity atmosphere of 25 ° C. and 60%, and molded every 2 weeks under the above-mentioned molding conditions, and the etching appearance was compared with the initial state and judged. When the life of the prepreg is exhausted, void residual flow is insufficient, so it is possible to make a simple judgment simply by checking the appearance.

(Examples 2 to 10) Laminates were prepared and evaluated in the same manner as in Example 1 except that the epoxy resin composition of the prepreg was changed. The results are shown in Table 1.

Comparative Example 1 A laminate was prepared in the same manner as in Example 1 except that the epoxy resin composition of the prepreg was the usual FR-4 composition containing no guanidine compound having an aromatic ring. Created and evaluated. The results are shown in Table 1.

(Comparative Example 2) 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. Next, an oxidation treatment generally called black treatment was applied to roughen the circuit surface to prepare an inner layer material. Next, a normal FR-4 prepreg (180 μm thick, resin content 50%) composed only of epoxy resin, aromatic diamine, and dicyandiamide was overlaid on both sides of the above inner layer material one by one, and the upper surface was thickened. 18μ
m copper foils were stacked one by one, heating was started from room temperature, and the material was molded by a vacuum press at a temperature rising speed of 2.7 ° C./min and a maximum attainable temperature of 170 ° C. The time required to reach the maximum temperature was about 70 minutes. This is because the prepreg needs a sufficient time to fill the concave portion of the inner layer circuit, 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 3) The composition of the prepreg of Example 2 was used.
A laminated plate was prepared and evaluated in the same manner as in Comparative Example 2 except that the composition of No. 1 was used. The laminated plate characteristics are shown in Table 1.

[0026]

[Table 1]

In measuring solder heat resistance, Examples 5 and 1 were used.
In 0 and Comparative Example 2, it was found that blisters were generated when the severe moisture absorption treatment was performed. However, when the soldering condition is floated instead of immersion, no blistering occurs and it is considered that there is no practical problem in this respect.

[0028]

As described above, the thermosetting undercoating agent is applied to both surfaces of the circuit-processed double-sided copper-clad laminate in advance, and the recesses between the circuits are filled with resin in order to dry it. Since no bubbles are present in a portion, voids are not generated and good moldability can be obtained without applying pressure for a long time as in the conventional vacuum press. At the same time, since it is not necessary to change the type of prepreg depending on the residual copper foil rate of the inner layer circuit, it is possible to reduce the number of types of prepreg to about 1/5 or 1/10 of the conventional type. Furthermore,
It is expected that a lot of man-hours will be put into practicing manual prepreg set automation now.

Further, the function of burying the concave portion of the inner layer circuit, which is required for the conventional prepreg, becomes completely unnecessary, and the prepreg can be considered as an adhesive sheet having merely insulating properties. Therefore, it is possible to significantly reduce the manufacturing time of the multilayer printed wiring board, and by making the prepreg quick-curing, it is possible to achieve a productivity three to four times higher than the conventional one.

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Claims (3)

[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. After applying a thermosetting undercoating agent to both sides of the processed double-sided copper clad laminate, (a) an epoxy resin having two or more epoxy groups in one molecule on the both sides thereof (b) an aromatic diamine (C) Dicyandiamide (d) A method for producing a multilayer printed wiring board, which comprises stacking and laminating pressing a prepreg containing a resin composition comprising a guanide compound having an aromatic ring skeleton. 2. The resin composition contained in the prepreg has (b) an aromatic diamine of 0.1 to 0.8 with respect to (a) one equivalent of an epoxy resin having two or more epoxy groups in one molecule. Equivalent (c) Dicyandiamide 0.1-0.8 equivalent (d) Guanidine compound having aromatic ring skeleton 0.05
The method for producing a multilayer printed wiring board according to claim 1, wherein the production amount is about 0.6 equivalent. 3. The method for producing a multilayer printed wiring board according to claim 1, wherein the aromatic diamine (b) is an aromatic amine having a halogen group represented by the chemical formula 1. Embedded image (X ₁ represents halogen, X ₂ , X ₃ and X ₄ represent halogen or hydrogen.)