JPH11207740A - Prepreg and laminate - Google Patents

Abstract

(57) [Problem] To provide a prepreg capable of obtaining a laminate having high bending strength. SOLUTION: The present invention relates to a prepreg obtained by impregnating and drying an epoxy resin varnish prepared by containing a liquid crystal polyester fiber base material containing an epoxy resin, a curing agent, and a solvent having a boiling point of 150 ° C. or higher. In such a prepreg, the boiling point in 150 parts by weight of the prepreg is 150 ° C.
The content of the above solvent is adjusted to 0.2 parts by weight or less. Erosion of the liquid crystal polyester fiber substrate by a solvent having a boiling point of 150 ° C. or higher can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepreg and a laminate used for manufacturing a printed wiring board used for electric / electronic equipment and the like.

[0002]

2. Description of the Related Art Conventionally, a prepreg is prepared by impregnating a base material such as a glass cloth with a thermosetting resin varnish such as an epoxy resin.
It is prepared by heating, drying and semi-curing. Then, the required number of the prepregs are stacked, and if necessary, a metal foil such as a copper foil is stacked on one or both sides of the prepreg, and then heated and pressed to form a laminate, thereby forming a copper-clad laminate used for manufacturing a printed wiring board. Such a metal-clad laminate can be obtained.

[0003] When an epoxy resin is used as the thermosetting resin, a curing agent is used to ensure the storage stability of the prepreg containing the epoxy resin and the heat resistance of a laminate manufactured using the prepreg. Is generally difficult to dissolve using a high boiling point solvent such as dicyandiamide (Dicy). When an epoxy resin varnish is prepared by blending a hardly soluble curing agent such as dicyandiamide, the boiling point is 1
Unless the solvent is dissolved using a solvent at 50 ° C. or higher, it is often difficult to obtain an epoxy resin varnish in which an epoxy resin or a curing agent is uniformly dissolved at an appropriate viscosity.
It is common to prepare an epoxy resin varnish using a solvent at 50 ° C. or higher.

On the other hand, with the progress of high-density mounting of printed wiring boards in recent years, improvements in various characteristics such as lowering the dielectric constant and weight of the laminated board are required. As a countermeasure, it has been proposed to use a substrate using liquid crystal polyester fibers instead of a substrate using glass fibers. The above-mentioned boiling point of 1 is applied to the substrate using the liquid crystal polyester fiber.
It is possible to prepare a prepreg by impregnating and drying an epoxy resin varnish containing a solvent at 50 ° C. or higher, and to prepare a laminate using this prepreg.
No. 13 discloses an example.

[0005]

However, the bending strength of the laminate prepared using the above liquid crystal polyester fiber as a base material and an epoxy resin varnish containing a solvent having a boiling point of 150 ° C. or more is low. There is a problem that when a large force is applied to the laminate, such as when the laminate is punched out by a die to form an outer shape, the laminate may be broken or bent.

[0006] The present invention has been made in view of the above points, and has as its object to provide a prepreg capable of obtaining a laminate having high bending strength, and to provide a laminate having high bending strength. The purpose is to do so.

[0007]

A prepreg according to the present invention comprises a liquid crystal polyester fiber substrate, an epoxy resin,
A prepreg obtained by impregnating and drying an epoxy resin varnish prepared containing a curing agent and a solvent having a boiling point of 150 ° C. or more, and containing a solvent having a boiling point of 150 ° C. or more in 100 parts by weight of the prepreg. The amount is 0.2 parts by weight or less.

The invention according to claim 2 is characterized in that the liquid crystal polyester fiber base material is a liquid crystal polyester fiber nonwoven fabric produced by a wet papermaking method. The invention according to claim 3 is characterized in that the solvent having a boiling point of 150 ° C. or more is N, N-dimethylformamide. Further, in the invention of claim 4, the amount of resin in the prepreg is 40 parts by weight based on 100 parts by weight of the prepreg.
６０60 parts by weight.

The laminate according to the present invention is characterized in that the prepreg and the metal foil are formed by lamination and integrated.

[0010]

Embodiments of the present invention will be described below. In the present invention, as the epoxy resin used for preparing the epoxy resin varnish, any epoxy resin having two or more epoxy groups in one molecule can be used without particular limitation. For example, bisphenol A type Epoxy resin, bisphenol F type epoxy resin, phenol novolak type epoxy resin, bisphenol A novolak type epoxy resin, cresol novolak type epoxy resin, diaminodiphenylmethane type epoxy resin and some of the hydrogen atoms in these epoxy resin structures are halogenated A single product, a modified product, or a mixture of an epoxy resin or the like which has been made flame-retardant by the conversion can be used. In particular, the use of one or more epoxy resins selected from bisphenol A type epoxy resin, tetrabromobisphenol A type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, and bisphenol A novolak type epoxy resin can provide excellent electric power. It is preferable because a laminate having both characteristics and physical characteristics and a balance between the two can be obtained. In addition, a plurality of the above epoxy resins may be used in combination.

In the present invention, dicyandiamide is generally used as a curing agent for preparing an epoxy resin varnish, but is not particularly limited thereto, and an amide-based curing agent such as an aliphatic polyamide may be used. , Amine, hardeners such as ammonia, triethylamine and dimethylamine, phenolic resin-based hardeners such as phenol novolak resin, cresol novolak resin, p-xylene-novolak resin, and hardeners such as acid anhydrides also have boiling points. It can be applied in the case of an epoxy resin varnish using a solvent at 150 ° C. or higher. Two or more of these curing agents can be used in combination.

The curing accelerator which can be contained in the epoxy resin varnish is not particularly limited, but tertiary amines such as triethyldiamine and benzyldimethylamine, 2-methylimidazole, and 2-ethyl- Examples thereof include imidazoles such as 4-methylimidazole and 2-phenylimidazole, organic phosphines such as tributylphosphine and triphenylphosphine, and tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate and triphenylphosphine tetraphenylborate. Can be. Two or more of these curing accelerators can be used in combination.

The filler which can be added to the epoxy resin varnish as required is not particularly limited, but may be alumina, silica, calcium carbonate, talc, clay, barium sulfate, aluminum hydroxide or the like. Inorganic powder filler, glass fiber, pulp fiber,
Examples thereof include fibrous fillers such as aramid fibers and ceramic fibers. Two or more of these fillers can be used in combination.

In the present invention, the epoxy resin varnish has a boiling point of 1 in order to obtain a uniform solution having an appropriate viscosity.
It contains a high boiling point solvent of 50 ° C. or higher. Boiling point is 15
Examples of the solvent at 0 ° C or higher include amides such as N, N-dimethylformamide (DMF) and N, N-dimethylacetamide. Although the upper limit of the boiling point is not particularly set, it is 165 in consideration of a practical solvent.
It is about ° C. By using a solvent having a boiling point of 150 ° C. or more, even if a hardly soluble curing agent such as dicyandiamide or a hardly soluble epoxy resin is used, the curing agent or the epoxy resin may have an appropriate viscosity. To obtain an epoxy resin varnish uniformly solutionized. When N, N-dimethylformamide is used as the solvent having a boiling point of 150 ° C. or higher, an epoxy resin varnish having a particularly appropriate viscosity can be easily obtained.

As the solvent, such a boiling point is 150 ° C.
A solvent having a boiling point of less than 150 ° C. can be used in combination with the above. Examples of the solvent having a boiling point of less than 150 ° C. include amides such as formamide, ethers such as ethylene glycol monomethyl ether, ketones such as acetone and methyl ethyl ketone (MEK), alcohols such as methanol and ethanol, and aromatics such as benzene and toluene. Group hydrocarbons and the like can be used. As described above, when a solvent having a boiling point of 150 ° C. or more and a solvent having a boiling point of less than 150 ° C. are used in combination, the mixing ratio of the two greatly changes depending on the type of the epoxy resin and the curing agent, and the desired varnish viscosity. However, for example, a solvent having a boiling point of 150
The range of about 300 to 1300 parts by weight of the solvent having a temperature of less than C is preferable.

Thus, the above epoxy resin, curing agent,
An epoxy resin varnish can be obtained by mixing a curing accelerator, a filler, and a solvent. The amounts of these components vary greatly depending on the type of each component, and thus cannot be specified unconditionally. For example, the curing agents 1 to 5 are added to 100 parts by weight of the epoxy resin.
Parts by weight, 0.03 to 0.3 parts by weight of curing accelerator, solvent 25
The range of 0 to 700 parts by weight is preferred.

On the other hand, in the present invention, a substrate made of liquid crystal polyester fiber is used as the substrate, and a nonwoven fabric or woven fabric of liquid crystal polyester fiber can be used. The liquid crystal polyester fiber can be obtained by melt-spinning a liquid crystal polyester resin. The liquid crystal polyester resin is a polymer capable of forming an anisotropic compatible layer, and is preferably composed of a wholly aromatic polyester resin.
No. 5306 (International publication number WO / 96/1530)
The one disclosed in 6) can be used. A strand obtained by bundling ultrafine filaments obtained by melt-spinning the liquid crystal polyester resin with a sizing agent is used as a fiber, and the fiber is woven into a woven fabric, or the fiber is cut to an appropriate length. A non-woven fabric made into a thin layer by a dry or wet process can be used as a substrate. Among them, a nonwoven fabric manufactured by a wet papermaking method of forming a slurry in which fibers are dispersed in white water has a uniform fiber distribution state, and can be impregnated with an epoxy resin uniformly, and has a laser processing property and the like. This is preferable because the drillability is good.

A prepreg can be obtained by impregnating the liquid crystal polyester fiber base material with the epoxy resin varnish described above and drying by heating to semi-harden the epoxy resin. The drying conditions are appropriately determined by setting the temperature and time according to the resin and the curing agent used. If the drying temperature is lower than the boiling point of the solvent used, the solvent is difficult to evaporate, so it is desirable to set the temperature to a temperature higher than the boiling point of the solvent, but it contains two or more solvents having different boiling points. When using epoxy resin varnish, if drying is performed at a higher temperature than the solvent with the higher boiling point, the solvent with the lower boiling point evaporates rapidly, causing irregularities on the surface of the prepreg, and lamination using this prepreg. When the board is manufactured, bubbles are likely to be generated in the laminated board, which may cause a problem in electrical characteristics. Therefore, it is preferable to appropriately adjust the boiling point and the amount of the solvent used.

It is preferable to adjust the impregnating amount of the prepreg so that the amount of the resin is 40 to 60 parts by weight of the epoxy resin based on 100 parts by weight of the prepreg. When the resin amount of the prepreg is in this range, the moldability when molding a laminate using this prepreg becomes good,
The heat resistance of the laminate obtained by using the prepreg is improved.

In preparing the prepreg by impregnating the liquid crystal polyester fiber base material with the epoxy resin varnish and drying by heating as described above, a part of the solvent mixed in the epoxy resin varnish remains in the prepreg. In particular, a high boiling point solvent having a boiling point of 150 ° C. or more tends to remain. The present inventors have conducted various studies and found that the strength of the liquid crystal polyester fiber base material is reduced by the erosion of the remaining boiling point by a solvent having a boiling point of 150 ° C. or higher. This is one of the causes of a decrease in the bending strength of a laminated plate using a material, and has solved the conventional problems. That is, by preparing the prepreg so that the content of the solvent having a boiling point of 150 ° C. or more in the prepreg is 0.2 parts by weight or less based on 100 parts by weight of the prepreg, the bending strength of the obtained laminate is obtained. Has been found to be able to enhance The content of the solvent having a boiling point of 150 ° C. or higher in the prepreg is 0.1% based on 100 parts by weight of the prepreg.
In the case of a prepreg exceeding 2 parts by weight, the liquid crystal polyester fiber base material is eroded by a solvent having a boiling point of 150 ° C. or higher,
This causes a problem that the bending strength of the laminate obtained using the prepreg is reduced. Boiling point in prepreg 15
In order to prepare a prepreg having a solvent content of 0 ° C. or more and 0.2 parts by weight or less based on 100 parts by weight of the prepreg, a boiling point of 150 ° C.
It can be carried out by adjusting the amount of the solvent described above, or by adjusting the heating temperature and the heating time during heating and drying. When a solvent having a boiling point of 150 ° C or more and a solvent having a boiling point of less than 150 ° C are used in combination, the residual amount of the solvent having a boiling point of less than 150 ° C is much smaller than the residual amount of the solvent having a boiling point of 150 ° C or more. So it doesn't matter.

In the present invention, the boiling point of the prepreg is 1
For the content of the solvent at 50 ° C or higher, the gas generated during the measurement of the volatile component should be sampled and analyzed by gas chromatography to the value of the volatile component measured by heating according to JIS standard C6521. Is a value obtained by multiplying the composition ratio of the solvent component having a boiling point of 150 ° C. or higher among the composition ratios of the volatile components obtained by the above method.

Then, a required number of the prepregs obtained as described above are laminated, and a metal foil such as a copper foil is laminated on one or both sides of the prepreg. It is possible to obtain a metal-clad laminate such as a copper-clad laminate used in the above.

[0023]

Next, the present invention will be described specifically with reference to examples. (Example 1) 94 parts by weight of a tetrabromobisphenol A type epoxy resin ("YDB-500" manufactured by Toto Kasei Co., Ltd .: epoxy equivalent 500) as a solid content, and a cresol novolac type epoxy resin ("YDCN-22" manufactured by Toto Kasei Co., Ltd.)
0 ": 13 parts by weight of the epoxy equivalent 220) as a solid content, 2.8 parts by weight of dicyandiamide as a curing agent, and 0.2 parts of 2-ethyl-4-methylimidazole as a curing agent.
One part by weight, 55 parts by weight of N, N-dimethylformamide (boiling point: 153 ° C.) as a solvent and 500 parts by weight of methyl ethyl ketone (boiling point: 80 ° C.) were blended to prepare an epoxy resin varnish.

This epoxy resin varnish was weighed at 70 g / m
² was wet impregnated into a wet-laid nonwoven fabric made of liquid crystal polyester fiber (manufactured by Nippon Vileen Co., Ltd.) and dried by heating under the conditions of a maximum temperature of 165 ° C. and a heating time of 4 minutes.
A prepreg having a weight% of 170 ° C. and a gel time of 330 seconds was obtained. The obtained prepreg was heated at 160 ° C. for 15 minutes in accordance with JIS standard C6521, and the volatile content was measured. As a result, the values shown in the column of “volatile content” in Table 1 were obtained. Also, after sampling the gas generated during this heating, the composition ratio of each gas boiling point was analyzed by gas chromatography / mass analyzer. Obtained. The value of the volatile component is multiplied by the component ratio of N, N-dimethylformamide, which is a component having a boiling point of 150 ° C. or higher in the constituent ratio of the volatile component, to obtain a solvent having a boiling point of 150 ° C. or higher with respect to 100 parts by weight of the prepreg. Was determined to be 0.1%.
It was 9 parts by weight.

Next, 11 prepregs obtained as described above were stacked, and a copper foil having a thickness of 35 μm was further stacked on both outer sides of the prepregs.
The laminate was formed by heating and pressing under the conditions of 70 ° C., a pressure of 3.9 Pa, and a time of 120 minutes to obtain a 1.6 mm-thick double-sided copper-clad laminate. Example 2 A resin amount was 50% by weight and a gel time at 170 ° C. was 330 as in Example 1, except that the heating and drying were performed at a maximum temperature of 170 ° C. and a heating time of 4 minutes. Seconds of prepreg were obtained. The content of the solvent having a boiling point of 150 ° C. or more based on 100 parts by weight of this prepreg was determined in the same manner as in Example 1, and it was 0.17 parts by weight. Then, using this prepreg, a double-sided copper-clad laminate was obtained in the same manner as in Example 1.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the amount of the solvent was set to 70 parts by weight of N, N-dimethylformamide (boiling point: 153 ° C.) and 500 parts by weight of methyl ethyl ketone (boiling point: 80 ° C.). Thus, an epoxy resin varnish was prepared. This epoxy resin varnish was impregnated into the same wet-laid nonwoven fabric made of liquid crystal polyester fiber as in Example 1, and heated and dried under the same conditions as in Example 1 to obtain a prepreg. The content of the solvent having a boiling point of 150 ° C. or more based on 100 parts by weight of the prepreg was determined in the same manner as in Example 1. As a result, it was 0.27 parts by weight. Then, using this prepreg, a double-sided copper-clad laminate was obtained in the same manner as in Example 1.

Comparative Example 2 The procedure of Example 1 was repeated except that the heating and drying conditions were a maximum temperature of 160 ° C. and a heating time of 4 minutes.
A prepreg having a gel time at 330 ° C. of 330 seconds was obtained. The content of the solvent having a boiling point of 150 ° C. or more based on 100 parts by weight of the prepreg was determined in the same manner as in Example 1, and it was 0.26 part by weight. Using this prepreg, a double-sided copper-clad laminate was obtained in the same manner as in Example 1.

The bending strength of the double-sided copper-clad laminates obtained in Examples 1 and 2 and Comparative Examples 1 and 2 was measured. The bending strength was measured in accordance with JIS C6481 after removing the copper foil on the surface by etching. As shown in Table 1, it was confirmed that Examples 1 and 2 had better bending strength than Comparative Examples 1 and 2.

[0029]

[Table 1]

[0030]

As described above, according to the first aspect of the present invention, a liquid crystal polyester fiber substrate is impregnated with an epoxy resin varnish prepared by containing an epoxy resin, a curing agent, and a solvent having a boiling point of 150 ° C. or more. A prepreg obtained by drying and having a boiling point of 150 ° C. in 100 parts by weight of the prepreg;
Since the content of the solvent is not more than 0.2 parts by weight, it is possible to suppress the base material made of liquid crystal polyester fiber from being eroded by a solvent having a boiling point of 150 ° C. or more. A laminate having high bending strength can be obtained by using a prepreg.

According to the second aspect of the present invention, the non-woven fabric made of the liquid crystal polyester fiber manufactured by the wet papermaking method is used as the base material made of the liquid crystal polyester fiber. Is uniform, the epoxy resin can be uniformly impregnated, and the laser processing property and drilling property of the laminated board manufactured using this nonwoven fabric can be improved.

According to the third aspect of the present invention, since N, N-dimethylformamide is used as the solvent having a boiling point of 150 ° C. or higher, an epoxy resin varnish having an appropriate viscosity can be easily obtained. . Claim 4
In the invention, the amount of resin in the prepreg is reduced by a prepreg weight of 1
Since the amount is adjusted to 40 to 60 parts by weight with respect to 00 parts by weight, the moldability when forming a laminate using this prepreg is improved, and the heat resistance of the laminate obtained using the prepreg is improved. The property becomes good.

In the laminate according to the present invention, the prepreg and the metal foil are integrally formed by laminating, so that the liquid crystal polyester fiber base material has a boiling point of 150 ° C.
Erosion by the above-mentioned solvent is suppressed, and a high bending strength can be obtained.

Continuation of the front page (51) Int.Cl. ⁶ Identification symbol FI C09D 163/00 C09D 163/00 // B29K 63:00 105: 08 (72) Inventor Kazuhiro Tarukawa 1048 Odakadoma, Kazumasa, Osaka Prefecture Matsushita Electric Works, Ltd. In the formula company

Claims (5)

[Claims] 1. A prepreg obtained by impregnating and drying an epoxy resin varnish prepared by adding an epoxy resin, a curing agent, and a solvent having a boiling point of 150 ° C. or higher to a substrate made of liquid crystal polyester fiber. A prepreg characterized in that the content of a solvent having a boiling point of 150 ° C. or more in 100 parts by weight of the prepreg is 0.2 parts by weight or less. 2. The prepreg according to claim 1, wherein the liquid crystal polyester fiber base material is a liquid crystal polyester fiber nonwoven fabric produced by a wet papermaking method. 3. The method according to claim 1, wherein the solvent having a boiling point of 150 ° C. or more is N, N-
2. The composition according to claim 1, which is dimethylformamide.
Or the prepreg according to 2. 4. The prepreg according to claim 1, wherein the amount of the resin in the prepreg is 40 to 60 parts by weight based on 100 parts by weight of the prepreg. 5. A laminate, wherein the prepreg according to claim 1 and a metal foil are laminated and integrated.