JPH08176324A - Production of prepreg - Google Patents

Abstract

PURPOSE: To obtain a heat-resistant and rapidly curable prepreg, capable of largely shortening a molding time, and useful for electric laminates, etc., by impregnating a varnish containing a specific epoxy resin in a fiber substrate and subsequently drying the impregnated varnish. CONSTITUTION: A varnish comprising an epoxy resin composition containing (A) epoxy resins having two or more epoxy groups, which contain an epoxy resin of formula I (G is group of formula II) in an equivalent ratio of 10-50%, (B) an aromatic polyamine [e.g. bis(4-amino-3-ethyl-5-methylphenyl)methane], and (C) a guanide compound (e.g. 1-o-tolyldiguanide) preferably in an equivalent ratio of 1, 0.1-0.8, 0.05-0.8, respectively, is impregnated in a fiber substrate and subsequently dried to obtain the objective prepreg. (D) Dicyandiamide is preferably further added to the composition in an amount of 0.1-0.8 equivalent per equivalent of the component A.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a prepreg used for electrical laminates such as copper clad laminates and multilayer printed wiring boards which require heat resistance and water absorption resistance, and particularly the time required for forming the laminate. The present invention relates to a method of manufacturing a prepreg for shortening.

[0002]

2. Description of the Related Art Conventionally, electrical laminates such as copper-clad laminates are made by impregnating glass fiber or paper with thermosetting resin such as epoxy resin or phenol resin to form prepregs. It is manufactured by stacking, laminating metal foils such as copper foils if necessary, and heating and pressurizing this. Further, the multilayer prepreg wiring board, a circuit is formed on the surface of the laminate obtained by the above method as an inner layer circuit board, usually prepreg and a metal foil are stacked on both sides,
It is manufactured by heat and pressure molding. These laminates are
In recent years, the tendency toward high-density mounting and high integration of printed wiring boards has increased, and the demands for various characteristics such as workability, heat resistance, and moldability have become more sophisticated and multifaceted. Among them, regarding moldability, it is strongly desired that the molding time can be shortened without deteriorating other properties.
Therefore, shortening the curing time of the resin used for the prepreg has been studied. For example, in the case of an epoxy resin, various combinations of a curing agent and a curing accelerator have been proposed.

[0003]

However, although the molding time can be shortened to some extent in any of the formulations,
This is not sufficient, and if it is attempted to further shorten the molding time, disadvantages such as deterioration in heat resistance and electrical properties after water absorption treatment will appear. In particular, regarding resins having high heat resistance and water absorption resistance, the glass transition temperature of the cured product is high, but the reaction leading to final curing is slow, and it is currently very difficult to shorten the molding time. As a result of various studies on the forming technology for laminated plates, the present inventors have succeeded in achieving a shortening of the forming time, which was insufficient with the conventional technology, without deteriorating other properties. .

[0004]

SUMMARY OF THE INVENTION The present invention provides a varnish comprising an epoxy resin composition containing (a) an epoxy resin having two or more epoxy groups, (b) an aromatic polyamine, and (c) a guanide compound. In a method of manufacturing a prepreg in which a fiber base material is impregnated and dried, an epoxy resin having an epoxy group of 10 to 50% in an epoxy resin equivalent ratio (hereinafter, referred to as a dicyclopentadiene phenol type epoxy resin) is used. ) Is a prepreg manufacturing method.

[0005]

Embedded image

In the present invention, as the epoxy resin (a) having two or more epoxy groups, any epoxy resin conventionally used for electrical insulation can be used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin. Resin, bisphenol S type epoxy 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 a biphenyl skeleton (biphenyl type Epoxy resin), dicyclopentadiene phenol type epoxy resin, naphthalene type epoxy resin, epoxy resin having a limonene skeleton, and the like. These may be used alone or in combination of several kinds.
Among such epoxy resins, the dicyclopentadiene phenol type epoxy resin has extremely low water absorption of the cured product, good heat resistance and flexibility when heated,
It is preferably used in the present invention.

Further, in order to impart flame retardancy, the above epoxy resin is blended with brominated epoxy resin, and the above epoxy resin and epoxy tetrabromobisphenol A are blended.
And co-condensing bisphenol A, blending the above epoxy resin with epoxy tetrabromobisphenol A and bisphenol A, blending the above epoxy resin with tetrabromobisphenol A, or
Any method such as blending the above-mentioned epoxy resin with brominated epoxyphenol novolac is possible.

The dicyclopentadiene phenol type epoxy resin is obtained by reacting a phenol compound and dicyclopentadiene under an acid catalyst and then reacting with epichlorohydrin to form a glycidyl ether, and has a water-repellent dicyclopentadiene skeleton. The main chain is a carbon-carbon bond having a relatively long length, particularly excellent water-absorbing properties, and has a feature that flexibility is high and a cross-linking density after curing is relatively high. Therefore, the swelling phenomenon in the component mounting process, which is a problem with a substrate having a high glass transition temperature and a particularly small thickness, is extremely small.

The amount of the dicyclopentadiene phenol type epoxy resin compounded is determined from the relationship between the curing rate and the water absorption property. That is, it is preferably contained in an equivalent ratio of 10 to 50% with respect to all epoxy resins. 10%
If it is less than 50%, the effect of improving the water absorption resistance is small, and if it exceeds 50%, the reaction rate becomes slow. Therefore, when molded for a short time, the crosslink density of the cured product becomes low, and the glass transition temperature becomes low. The cost will be high.

Next, regarding the aromatic polyamine, 4,
4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, metaphenylenediamine, 4,
4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 3,3'-dimethoxy-4,
4'-diaminodiphenyl, 3,3'-dimethyl-4,
4'-diaminodiphenyl, 2,2'-dichloro-4,
4'-diamino-5,5'-dimethoxydiphenyl,
2,2 ', 5,5'-Tetrachloro-4,4'-diaminodiphenyl, 4,4'-methylene-bis (2-chloroaniline), 2,2', 3,3'-tetrachloro-4 ，
4'-diaminodiphenylmethane, bis (4-amino-
2-chloro-3,5-diethyldiphenyl) methane,
4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminobenzanilide, 3,3'-dihydroxy-4,4'-diaminobiphenyl, 9,9'-bis (4 Examples include -aminophenyl) fluorene and 9,10-bis (4-aminophenyl) anthracene.

The guanide compound generally means a compound having a guanidine structure, and includes 1,3-diphenylguanidine, di-orthotolylguanidine, 1-orthotolyldiguanide, α-2,5-dimethylguanide, α,
ω-diphenyldiguanide, 5-hydroxynaphthyl-
1-diguanide, phenyldiguanide, α, α'-bisguanylguanididinodiphenyl ether, p-chlorophenyldiguanide, α-benzyldiguanide, α, ω
-Dimethyldiguanide, α, α'-hexamethylenebis [ω- (p-chlorophenol)] diguanide, o-tolyldiguanide zinc salt, diphenyldiguanide iron salt, phenyldiguanide copper salt, diguanide nickel Salt, ethylenebisdiguanide hydrochloride, lauryldiguanide hydrochloride,
Examples thereof include phenyldiguanide oxalate, mono-substituted or di-substituted alkyl-modified phenyl diguanide, and the like.

The advantage of these guanide compounds is that they generate a large amount of heat when they react with an epoxy group to open the epoxy ring. Therefore, in a reaction system in which an epoxy resin and an addition polymerization are caused by heating, the reaction does not occur. Remarkably promoted. In the present invention, shortening of the molding time is achieved by utilizing this feature. When the reaction of the epoxy resin was examined by a scanning calorimeter, 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 20 to 40 mJ per 1 mg of the resin. The heat generation during the reaction is small, the reaction initiation temperature is about 150 ° C, and the reaction activation temperature is about 170 ° 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, aromatic polyamine, and guanide compound, 60 to 140 per 1 mg of resin.
The amount of heat generated during the reaction with mJ is large, the reaction initiation temperature is about 130 ° C, and the reaction activation temperature is about 150 ° C. That is,
This means that a 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. Regarding the aromatic polyamine, the heat resistance is improved as the blending amount increases in a range not exceeding 1.2 equivalents to 1 equivalent of the epoxy resin, but the blending amount must be determined in consideration of the storage stability of the prepreg. I won't. Therefore, when the compounding amount is in the range of more than 0.8 equivalent, it is difficult to satisfy the storage requirement of 3 months which is usually required in the market. On the other hand, if the amount is less than 0.1 equivalent, the effect of adding the aromatic polyamine to the improvement of heat resistance cannot be sufficiently observed. Therefore, the blending amount of the aromatic polyamine is preferably in the range of 0.1 to 0.8 equivalent. Regarding the blending 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 less than 0.05 equivalent, the amount of heat generated is small and sufficient rapid curing property cannot be obtained. When the amount exceeds 0.8 equivalent, the moisture absorption amount tends to be large and the solder heat resistance tends to decrease. . Therefore, the compounding amount of 0.05 to 0.8 equivalent is appropriate.

Dicyandiamide is added as necessary to improve the adhesion to the copper foil or the curability. When dicyandiamide is used in combination, the amount of dicyandiamide blended is determined in consideration of the adhesion to the copper foil and the solder heat resistance when absorbing moisture. That is, when the amount is less than 0.1 equivalent with respect to 1 equivalent of the epoxy resin, the effect of addition is small from the viewpoint of improving the adhesiveness to the copper foil, and when the amount exceeds 0.8 equivalent, the moisture absorption is increased. As the amount increases, it tends to cause deterioration of solder heat resistance after moisture absorption treatment, leading to deterioration of storage stability.

There are no particular restrictions on the composition other than these. For example, to increase the adhesion with glass fiber,
For the purpose of adding a coupling agent exemplified by epoxysilane or aminosilane, or for further improving the plate thickness accuracy,
It is possible to add a polybutadiene rubber, a nitrile rubber, a nitrile butadiene rubber, or a carboxylic acid-modified, amine-modified, or epoxy-modified product thereof. In addition, there is no particular limitation on the addition of an imidazole compound, an adduct imidazole, a microencapsulation curing accelerator, a phosphine-based accelerator, an amine-based accelerator, or the like for adjusting the gel time of the prepreg or imparting further rapid curing property.

[0016]

The prepreg obtained according to the present invention is fast-curing, so that the heating and pressurizing time of the laminated plate can be greatly shortened. In the case of an epoxy resin laminated plate, it has become possible to shorten the molding time, which normally takes 120 to 200 minutes by one lamination molding, to about 40 to 60 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, it is possible to significantly reduce the molding time when molding the multilayer printed wiring board.

The dicyclopentadiene phenol type epoxy resin used in the present invention has a feature that it is particularly excellent in water absorption resistance as described above. Generally, most thermosetting resins have a polar group, and although they have good curability and heat resistance after curing, various properties after water absorption treatment often deteriorate. An aromatic polyamine is used as a curing agent in the epoxy resin composition according to the present invention. In this case, the water absorption resistance is kept good by the reaction between the epoxy resin containing the dicyclopentadiene phenol type epoxy resin and the aromatic polyamine. It was also found that the crosslink density also increased. Therefore, despite being quick-curing, the main thermal characteristics as a circuit board such as water absorption resistance such as solder heat resistance after water absorption treatment, heat resistance, and dimensional stability are excellent.

Further, in the production of a multilayer printed wiring board, by applying an undercoating agent to the inner layer circuit board in advance, the resin flow is small as compared with the case of using a conventional prepreg, so that the board thickness is reduced. The accuracy is good, the surface smoothness of the outer layer surface is high due to the effect of embedding the undercoat agent, and it is possible to form a fine pattern circuit.

[0019]

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

Example 1 A glass fiber woven fabric was impregnated with an epoxy resin composition composed of an epoxy resin having the composition ratio shown in Table 1, an aromatic polyamine and 1-orthotolyldiguanide, and dried to obtain an epoxy resin composition. A prepreg having a thickness of 180 μm and a resin content of 42% was obtained. 6 prepregs and 1 on each side
8μm thick copper foils are stacked and pressure is 30kg /
Pressurize to cm ² , start heating from room temperature, heating rate about 18
Molding was carried out at a maximum reaching 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 ° C.) was almost equal to the glass transition temperature of the prepreg in 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. As a result, the heating time required for molding was 40 minutes, and Table 1 shows the characteristics of the laminated plate 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 A glass fiber woven fabric was impregnated with an epoxy resin composition composed of an epoxy resin having the composition ratio shown in Table 1, an aromatic polyamine, dicyandiamide, and p-chlorophenyldiguanide, and dried to obtain an epoxy resin composition. , 180μ
A prepreg having a thickness of m and a resin content of 42% was obtained. Six pieces of this prepreg and 18 μm thick copper foil were overlaid on both sides of the prepreg, and pressure was applied to the pressure of 30 kg / cm ² with a laminating press, heating was started from room temperature, and the temperature rising rate was about 18 ° C./minute and the maximum reached temperature was 170 ° C. Molded. The time required to reach the maximum temperature was about 10 minutes, and the heating time required for molding was 40 minutes. Table 1 shows the characteristics of the laminated plate during the heating time.

Example 3 A glass fiber woven cloth was impregnated with an epoxy resin composition composed of an epoxy resin having a composition ratio shown in Table 1, an aromatic polyamine and phenyldiguanide,
After drying, a prepreg having a thickness of 180 μm and a resin content of 42% was obtained. Six of these prepregs and 18 μm thick copper foil were laid on both sides of the prepreg, and a pressure of 30 kg / cm ² was applied by a laminating press, heating was started from room temperature, and a heating rate was about 18 ° C./min.
Molding was performed at a maximum temperature of 170 ° C. The time required to reach the maximum temperature was about 10 minutes, and the heating time required for molding was 40 minutes. Table 1 shows the characteristics of the laminated plate during the heating time.

Comparative Example 1 A glass fiber woven cloth was impregnated with an epoxy resin composition containing an epoxy resin containing no dicyclopentadiene phenol type epoxy resin, an aromatic polyamine and 1-orthotolyldiguanide, and dried. Thus, a prepreg having a thickness of 180 μm and a resin content of 42% was obtained. Six pieces of this prepreg and 18 μm thick copper foil were overlaid on both sides of the prepreg, and pressure was applied to the pressure of 30 kg / cm ² with a laminating press, heating was started from room temperature, and the temperature rising rate was about 18 ° C./minute and the maximum reached temperature was 170 ° C. Molded. The time required to reach the maximum temperature was about 10 minutes, and the heating time required for molding was 40 minutes. Table 1 shows the characteristics of the laminated plate during the heating time.

Comparative Example 2 A glass fiber woven fabric was impregnated with an epoxy resin composition containing only an epoxy resin containing no dicyclopentadiene phenol type epoxy resin, an aromatic polyamine and dicyandiamide and dried to give a thickness of 180 μm. A prepreg having a resin content of 42% was obtained.
Six pieces of this prepreg and 18 μm thick copper foil were overlaid on both sides of the prepreg, and pressure was applied to the pressure of 30 kg / cm ² with a laminating press, heating was started from room temperature, and the temperature rising rate was about 18 ° C./minute and the maximum reached temperature was 170 ° C. Molded. The time required to reach the maximum temperature was about 10 minutes, and the heating time required for molding was 120 minutes. Table 1 shows the characteristics of the laminated plate during the heating time.

(Comparative Example 3) A glass fiber woven fabric was impregnated with an epoxy resin composition composed of an epoxy resin containing a dicyclopentadiene phenol type epoxy resin, an aromatic polyamine and dicyandiamide and dried to obtain 1
A prepreg having a thickness of 80 μm and a resin content of 42% was obtained. Six of these prepregs and 18 μm thick copper foil were laminated on both sides of the prepreg, pressure was applied to 30 kg / cm ² by a laminating press, heating was started from room temperature, a temperature rising rate was about 18 ° C./min, and a maximum reached temperature was 17
Molding was performed at 0 ° C. It took about 10 minutes to reach the maximum temperature, and the heating time required for molding was 120 minutes.
It was a minute. Table 1 shows the characteristics of the laminated plate during the heating time.

[0028]

[Table 1]

[0029]

As described above, the prepreg obtained by the method of the present invention is excellent in various properties after water absorption treatment, is heat resistant, and is rapidly curable, so that it can be used as an electrical laminate. The time required for molding can be significantly reduced. Further, also in the molding of a multilayer printed wiring board, the molding time can be shortened by using it as an interlayer insulating material. In particular, by applying an undercoating agent to the surface of the inner layer circuit board, not only the molding time is shortened, but also the thickness accuracy of the obtained board is good, and a multilayer printed wiring board having excellent surface smoothness is obtained. be able to.

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Claims (4)

[Claims] 1. A prepreg for impregnating and drying a varnish comprising an epoxy resin composition containing (a) an epoxy resin having two or more epoxy groups, (b) an aromatic polyamine, and (c) a guanide compound in a fiber substrate. Of the epoxy resin, in an equivalent ratio of 10 to 50.
% Is an epoxy resin represented by the following chemical formula (1): a method for producing a prepreg. Embedded image 2. The epoxy resin composition, wherein the equivalent ratio is (b) an aromatic polyamine of 0.1 to 0. 0 to 1 equivalent of (a) an epoxy resin having two or more epoxy groups.
The method for producing a prepreg according to claim 1, wherein the amount is 8 equivalents and the guanide compound (c) is 0.05 to 0.8 equivalents. 3. A varnish made of an epoxy resin composition containing (a) an epoxy resin having two or more epoxy groups, (b) an aromatic polyamine, (c) a guanide compound, and (d) dicyandiamide is used as a fiber base material. The method for producing a prepreg in which the epoxy resin represented by the chemical formula (1) accounts for 10 to 50% of the epoxy resin in an equivalent ratio. 4. The epoxy resin composition, wherein the equivalent ratio is (b) an aromatic polyamine of 0.1 to 0. 0 to 1 equivalent of (a) an epoxy resin having two or more epoxy groups.
The method for producing a prepreg according to claim 3, wherein the amount is 8 equivalents, (c) the guanide compound is 0.05 to 0.8 equivalents, and (d) the dicyandiamide is 0.1 to 0.8 equivalents.