JPH11343476A - Adhesive composition and copper-clad laminate using the same - Google Patents

Abstract

(57) [Problem] To provide an adhesive composition having good wet heat resistance and a copper-clad laminate using the same. An adhesive composition containing an epoxy resin, an elastomer having a carboxyl group, a curing agent, and a curing accelerator, wherein the curing accelerator includes the following components (A) and (B): A mixture of components is used. (A) Imidazole derivatives. (B) At least one of an aromatic carboxylic acid and an acid anhydride.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive composition used for printed wiring boards and the like, and more particularly, to an adhesive composition used for a flexible printed circuit board (hereinafter referred to as "FPC board"). The present invention relates to a copper-clad laminate using the same.

[0002]

2. Description of the Related Art Conventionally, adhesives used for printed wiring boards such as FPC boards are required to have properties such as adhesiveness, workability, and electrical insulation. Therefore, epoxy resins and acrylonitrile having a carboxyl group are required. -Butadiene rubber (N
An adhesive composition containing an elastomer such as BR) is widely used. Then, in order to control the reaction rate of this composition and increase the storage stability of the blended liquid, it has been proposed to blend an amine-based curing agent or an imidazole-based curing accelerator. The imidazole type is an anion polymerization type with respect to the epoxy resin, has a relatively long pot life and exhibits appropriate reactivity, so that workability can be improved, and medium temperature (80 to 120 ° C.) (Degree) There is an advantage that a cured body having a high heat deformation temperature can be obtained by a short-time heat treatment.

[0003]

However, in recent years, as electronic devices have become smaller and more multifunctional, higher performance adhesives have been required, and epoxy resins, elastomers, amine-based curing agents and Adhesives comprising imidazole-based curing accelerators have become unable to achieve high performance. That is, when an imidazole-based curing agent is used alone as a curing accelerator, the adhesiveness under high-temperature and high-humidity conditions becomes insufficient, or a layer composed of the adhesive causes appearance defects such as discoloration and swelling. Because. Therefore, there is a strong demand for the development of an adhesive composition having good wet heat resistance.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an adhesive composition having good wet heat resistance and a copper-clad laminate using the same.

[0005]

According to the present invention, there is provided an adhesive composition comprising an epoxy resin, an elastomer having a carboxyl group, a curing agent, and a curing accelerator. A first gist is an adhesive composition using a mixture of the following components (A) and (B) as the curing accelerator. (A) Imidazole derivatives. (B) At least one of an aromatic carboxylic acid and an acid anhydride.

The present invention also relates to a copper-clad laminate comprising an insulating film, an adhesive layer formed on the surface thereof, and a copper foil formed via the adhesive layer, A copper-clad laminate, the layer of which is made of the adhesive composition
The summary of the

That is, the present inventors have conducted a series of studies in order to obtain an adhesive composition having good wet heat resistance. In the process, an imidazole-based derivative having good properties other than wet heat resistance was used as it is, and a new substance was added to the derivative to improve the wet heat resistance.
As a result, for an adhesive composition containing an epoxy resin, an elastomer having a carboxyl group, and a curing agent,
As a curing accelerator, an imidazole derivative (component A)
And the use of at least one of the aromatic carboxylic acid and the acid anhydride (component (B)), it is possible to improve the wet heat resistance while maintaining good characteristics when the imidazole derivative is used. Ascertained, the present invention has been reached.

In particular, it has been found that the use of the aromatic carboxylic acid represented by the general formula (1) is highly effective when used in combination with the imidazole derivative of the component A. In addition, it has been found that the use of the imidazole derivative represented by the general formula (2) has a high effect when used in combination with the component B.
And it has been found that if the weight-based mixing ratio of the component A and the component B is set in a specific range, the effect of the combined use is higher.

Further, it has been found that it is preferable from the viewpoint of production efficiency and water resistance to use the epoxy resin, which is a constituent component of the adhesive composition, and an elastomer having a carboxyl group in advance. The reason why the water resistance is improved is not necessarily clear, but it is considered that unreacted carboxylic acid in the elastomer, which is considered to adversely affect the water resistance, can be reduced.

In a copper-clad laminate comprising an insulating film, an adhesive layer formed on the surface of the insulating film, and a copper foil formed via the adhesive layer, the adhesive layer is formed of the adhesive composition It has been found out that it is particularly preferable from the viewpoint of reliability that it is formed by an object.

[0011]

Next, an embodiment of the present invention will be described.

The adhesive composition of the present invention is obtained using an epoxy resin, an elastomer having a carboxyl group, a curing agent, and a curing accelerator.

The epoxy resin is not particularly limited, and a conventionally known epoxy resin is used. Among them, those having two or more epoxy groups in one molecule are preferable. Examples include glycidyl ether type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin and brominated epoxy resin, cycloaliphatic epoxy resin, heterocyclic epoxy resin and the like. These may be used alone or in combination of two or more. Among them, a brominated bisphenol A type epoxy resin is preferred from the viewpoint of the stability of the reaction solution when the epoxy resin is reacted with the elastomer having a carboxyl group in advance, and the adhesiveness, heat resistance and flame retardancy.

The carboxyl group-containing elastomer (hereinafter simply referred to as “elastomer”) used with the epoxy resin is not particularly limited.
For example, NBR having at least one carboxyl group in one molecule can be mentioned. As this NBR, for example,
Acrylonitrile and a copolymer rubber obtained by polymerizing butadiene by a conventionally known method, in which the terminal group is a carboxyl group, acrylonitrile, butadiene, and a polymerizable monomer containing a carboxyl group such as acrylic acid. Ternary copolymer rubber polymerized by a conventionally known method can be used. These may be used alone or in combination of two or more.

It is preferable that the amount of the elastomer is set in the range of 10 to 100 parts by weight based on 100 parts by weight of the epoxy resin. That is, the above 1
If the amount is less than 0 parts by weight, the adhesive strength of the adhesive layer formed by the adhesive composition may be reduced or the adhesive layer may become brittle. Conversely, if it exceeds 100 parts by weight, the electrical insulation of the adhesive layer may be reduced, or the heat resistance may be reduced.

The curing agent used together with the epoxy resin and the elastomer is not particularly limited, and examples thereof include amine-based curing agents such as aromatic polyamines, and acids and acid anhydrides. As the curing agent, an appropriate curing agent is selected according to the epoxy resin or the like. From the viewpoint of curing speed and solder heat resistance, an amine-based curing agent is preferable, and an aromatic polyamine is particularly preferable.

As the curing accelerator used together with the epoxy resin, elastomer and curing agent, a mixture of an imidazole derivative (component A) and at least one of an aromatic carboxylic acid and an acid anhydride (component B) must be used. This is because the greatest feature of the present invention is to improve the wet heat resistance by using these in combination.

The imidazole derivative of the component A is not particularly limited, and various derivatives may be used. These may be used alone or in combination of two or more. Among them, a compound represented by the following general formula (2), which has a high combined effect with the component B, is preferable.

[0019]

Embedded image

Specific examples of the compound represented by the general formula (2) include 2-methylimidazole and 2-ethyl-4
-Methylimidazole, 2-undecylimidazole,
1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-
Cyanoethyl-2-undecylimidazole, 2,4-
Diamino-6- (2-methyl-1-imidazolyl) -ethyl-1,3,5-triazine, 2,4-diamino-6
-(2-undecyl-1-imidazolylethyl) -1,
3,5-triazine, 2,4-diamino-6- (2-ethyl-4-methyl-1-imidazolylethyl) -1,
3,5-triazine.

As the aromatic carboxylic acid of the component B,
There is no particular limitation, and various types are used.
Among them, the combined effect with imidazole derivatives is high,
Those represented by the following general formula (1) are mentioned.

[0022]

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Specific examples of the compound represented by the general formula (1) include benzoic acid, 1,2-benzenedicarboxylic acid, 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,2,3 -Benzenetricarboxylic acid,
Examples thereof include 1,2,4-benzenetricarboxylic acid and 1,3,5-benzenetricarboxylic acid. Optimally, benzenedicarboxylic acid and benzenetricarboxylic acid, which are polyfunctional, are cited in that the degree of crosslinking of the cured product can be increased to further improve the wet heat resistance.

Examples of the acid anhydride of the component B include phthalic anhydride represented by the following chemical formula (3), trimellitic anhydride represented by the following chemical formula (4), and the following chemical formula ( Pyromellitic anhydride represented by 5) is mentioned.

[0025]

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[0026]

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[0027]

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The aromatic carboxylic acid and acid anhydride of the component B may be used alone or in combination of two or more.

The optimum combination of the above-mentioned component A and component B is a combination of 1-cyanoethyl-2-ethyl-4-methylimidazole and 1,2,4-benzenetricarboxylic acid. With such a combination,
Compared to the case of using the imidazole derivative alone,
This is because the wet heat resistance is greatly improved, and the adhesiveness and solder heat resistance are also improved.

It is preferable that the mixing ratio of the component A and the component B is set in a range of A / B = 1/10 to 1 / 0.1 by weight. More preferably, A / B = 1 /
It is 1.9 to 1 / 0.7. That is, if the amount of the B component exceeds 10 with respect to the A component 1, curing at a high temperature is required, and workability is deteriorated, or a cured body having a high heat deformation temperature cannot be obtained by heat treatment at a medium temperature for a short time. This is because there is a risk of doing so. Conversely, if the B component is less than 0.1 with respect to the A component 1, the effect of increasing the wet heat resistance in combination with the imidazole derivative may not be sufficiently obtained.

It is preferable that the curing accelerator is contained in the adhesive composition in an amount of more than 0 part by weight and not more than 60 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the curing agent. . That is, when the amount exceeds 60 parts by weight, the wet heat resistance is adversely affected, and further, the solder heat resistance and the adhesiveness may be reduced.

The adhesive composition of the present invention contains a flame retardant, an antioxidant, a reaction accelerator capable of accelerating a preliminary reaction between an epoxy resin and an elastomer, as long as the object of the present invention is not impaired. May be contained.

The adhesive composition of the present invention can be prepared by appropriately mixing the above-mentioned components, but is preferably prepared, for example, as follows. That is, first, an epoxy resin dissolved in a solvent such as methyl ethyl ketone and an elastomer dissolved in a solvent such as methyl ethyl ketone are blended at an appropriate ratio, and sufficiently stirred and mixed until uniform. Then, under predetermined conditions (for example, 70 ° C.
(× 40 minutes) to pre-react the epoxy resin with the elastomer to obtain a reaction product. Then, the reactant, the curing agent, the curing accelerator, and if necessary, other conventionally known materials are blended in an appropriate ratio, and the mixture is stirred and mixed according to a conventional method to form a liquid adhesive composition. You can get things.

The adhesive composition thus obtained is
Since a mixture of the component A and the component B is used as the curing accelerator, the combination of the components improves the wet heat resistance and also improves other characteristics. And when the epoxy resin and the elastomer are reacted in advance, the unreacted carboxylic acid in the elastomer does not exist,
The effect of increasing the water resistance is obtained.

The adhesive composition of the present invention is used as an adhesive for a copper-clad laminate as an example of its use.

As a copper-clad laminate using the adhesive composition of the present invention, specifically, for example, as shown in FIG. 1, an adhesive layer composed of the adhesive composition is formed on the surface of an insulating film 11. 12 is formed, and a copper-clad laminate in which a copper foil 13 is laminated via the adhesive layer 12 is exemplified.

Examples of the insulating film 11 include various films such as polyimide, polyester, epoxy resin and glass cloth (flexible type).

The copper-clad laminate of the present invention can be manufactured, for example, as follows. That is, first, the adhesive composition of the present invention is applied to the surface of the insulating film 11, and is heated and dried (for example, at 160 ° C. for 2 minutes) to remove the solvent, thereby forming the adhesive layer 12. The method for applying the adhesive composition is not particularly limited,
It can be performed by various methods such as a die coater and a roll coater. Then, the adhesive layer 12 and the copper foil 1
3 and then heated (for example, at 80 to 160 ° C. for 4 hours) to cure the adhesive layer 12 and bond the insulating film 11 and the copper foil 13 via the adhesive layer 12. The heating method is not particularly limited, and can be performed by a dryer such as an oven or various methods such as a heating press. Thus, the copper-clad laminate shown in FIG. 1 can be obtained.

The copper-clad laminate thus obtained is
Although it can be used for manufacturing a printed wiring board, it is particularly preferably used for manufacturing an FPC board.

Next, examples will be described together with comparative examples.

[0041]

Example 1 First, 125.2 g of a brominated bisphenol A type epoxy resin dissolved in methyl ethyl ketone.
(Solid content 70% by weight) and 58.4 g (solid content 35.2% by weight) of carboxyl group-containing NBR dissolved in methyl ethyl ketone were mixed and stirred until sufficiently uniform. Then, at about 70 ° C.,
The reaction was performed under the condition of time. After cooling the obtained reaction product, 4.5 g of an aromatic polyamine as a curing agent, 0.218 g of 1-cyanoethyl-2-ethyl-4-methylimidazole (CN) as a curing accelerator and 1,2,4-
A mixture of 0.282 g of benzenetricarboxylic acid (TMA) was added and dissolved and mixed to obtain an adhesive composition.

[0042]

Example 2 1-cyanoethyl-2- as a curing accelerator
0.218 g of ethyl-4-methylimidazole (CN)
And 1,2-benzenedicarboxylic acid (PA) 0.22
Except for using 3 g of the mixture, in the same manner as in Example 1,
An adhesive composition was obtained.

[0043]

Example 3 0.148 g of 2-ethyl-4-methylimidazole (2E4MZ) as a curing accelerator and
0.282 2,4-benzenetricarboxylic acid (TMA)
An adhesive composition was obtained in the same manner as in Example 1 except that the mixture of g was used.

[0044]

Example 4 Example 1 was repeated except that a mixture of 0.296 g of 2-undecylimidazole (C ₁₁ Z) and 0.282 g of 1,2,4-benzenetricarboxylic acid (TMA) was used as a curing accelerator. Similarly, an adhesive composition was obtained.

[0045]

Example 5 In the same manner as in Example 1, except that a mixture of 0.212 g of 2-phenylimidazole (2PZ) and 0.282 g of 1,2,4-benzenetricarboxylic acid (TMA) was used as a curing accelerator. Thus, an adhesive composition was obtained.

[0046]

Example 6 The procedure of Example 1 was repeated except that a mixture of 0.11 g of 2-methylimidazole (2MZ) and 0.282 g of 1,2,4-benzenetricarboxylic acid (TMA) was used as a curing accelerator. Thus, an adhesive composition was obtained.

[0047]

Example 7 2,4-diamino-6- as a curing accelerator
Example 1 except that a mixture of 0.48 g of (2-undecylimidazolyl) -ethyl-s-triazine (C ₁₁ ZA) and 0.282 g of 1,2,4-benzenetricarboxylic acid (TMA) was used. In the same manner as in the above, an adhesive composition was obtained.

[0048]

Example 8 1-cyanoethyl-2- as a curing accelerator
0.436 g of ethyl-4-methylimidazole (CN)
And 0.584 of 1,2,4-benzenetricarboxylic acid
An adhesive composition was obtained in the same manner as in Example 1 except that the mixture of g was used.

[0049]

Example 9 1-cyanoethyl-2- as a curing accelerator
0.436 g of ethyl-4-methylimidazole (CN)
An adhesive composition was obtained in the same manner as in Example 1 except that a mixture of 0.516 g of trimellitic anhydride was used.

[0050]

Example 10 1-cyanoethyl-2 as a curing accelerator
-Ethyl-4-methylimidazole (CN) 0.218
g and benzoic acid 0.164 g, except that a mixture was used in the same manner as in Example 1 to obtain an adhesive composition.

[0051]

Example 11 1-cyanoethyl-2 as a curing accelerator
-Ethyl-4-methylimidazole (CN) 0.218
g and pyromellitic anhydride were used in the same manner as in Example 1 except for using a mixture of 0.293 g of the adhesive composition.

[0052]

Example 12 1-cyanoethyl-
2-ethyl-4-methylimidazole (CN) and 1,
Example 1 except that a mixture with 2,4-benzenetricarboxylic acid (TMA) and trimellitic anhydride was used.
In the same manner as in the above, an adhesive composition was prepared.

[0053]

Comparative Example 1 An adhesive composition was obtained in the same manner as in Example 1 except that no curing accelerator was added.

[0054]

Comparative Example 2 1-cyanoethyl-2- as a curing accelerator
An adhesive composition was obtained in the same manner as in Example 1, except that only 0.5 g of ethyl-4-methylimidazole (CN) was used.

[0055]

Comparative Example 3 Except that 0.282 g of 1,2,4-benzenetricarboxylic acid (TMA) was used as a curing accelerator,
In the same manner as in Example 1, an adhesive composition was obtained.

The adhesive strength, wet heat resistance and solder heat resistance were measured and evaluated by the following methods using each of the above adhesive compositions. The results are shown in Tables 1 to 3 below.

[Adhesive Strength] Measured according to Method A (180 ° C. direction) based on JIS C 6481.

[Humidity and heat resistance] High temperature and high humidity conditions (121 ° C,
After leaving for 30 hours in a saturated state (2 atm), the adhesive strength was measured in the same manner as above. The appearance was evaluated as follows. In other words, x was observed when discoloration or swelling was observed a lot, and △ was observed when discoloration or swelling was observed to some extent but did not impair product reliability, and discoloration or swelling was not observed at all. Was circled.

[Solder Heat Resistance] After performing a treatment at 280 ° C. for 60 seconds in accordance with JIS C 6481, the adhesive strength was measured. In addition, the time until swelling occurred was measured.

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

[Table 3]

From the above results, all of the products of Examples were excellent in wet heat resistance. In particular, the product of Example 1 is only different from the product of Comparative Example 2 only in the curing accelerator, but has very good moisture and heat resistance, and has slightly improved adhesiveness and solder heat resistance. I was

[0064]

Example 13 The adhesive composition shown in Example 1 was applied to a polyimide film and then dried at 160 ° C. for 2 minutes to form an adhesive layer having a thickness of 25 μm. Then, a copper foil (1 oz) is placed on the adhesive layer surface,
The copper-clad laminate was manufactured by heating in an oven (130 ° C. × 4 hours). Since this copper-clad laminate was manufactured using the adhesive composition of Example 1, the copper-clad laminate was extremely excellent in wet heat resistance, and the copper foil was firmly adhered to the solder heat resistance. Therefore, it has high reliability and very high quality.

[0065]

As described above, the adhesive composition of the present invention contains an epoxy resin, an elastomer, a curing agent, and a curing accelerator, and contains an imidazole derivative ( A mixture of component (A) and at least one of aromatic carboxylic acid and acid anhydride (component (B)) is used. Therefore, by using the above mixture,
The wet heat resistance is improved, and the other properties are also good. Therefore, the adhesive composition of the present invention is suitable for an adhesive for a copper-clad laminate, and is particularly suitable for a copper-clad laminate used in the production of an FPC board which is disposed in a high-temperature, high-humidity environment. Ideal as an agent.

In particular, when the aromatic carboxylic acid of the component B is represented by the general formula (1), better heat and moisture resistance can be obtained. Further, when the imidazole-based derivative represented by the general formula (2) is used, the effect attributable to the combined use with the component B, that is, a favorable effect, is maintained without impairing the effect obtained from the imidazole-based derivative alone. Moist heat resistance can be obtained more effectively. When the weight-based mixing ratio of the component A and the component B is set in a specific range, a favorable curing accelerating ability can be exhibited, and a further improvement in wet heat resistance can be obtained.

Further, in the above adhesive composition, when an epoxy resin and an elastomer are reacted in advance and the reaction product is used, the unreacted elastomer disappears after the curing reaction, and the adhesive composition has excellent water resistance. Becomes In addition, by reacting in advance, the curing time can be shortened and the production efficiency can be improved as compared with the simultaneous mixing of all components.

When the above-mentioned adhesive composition is used as a material for forming the adhesive layer of the copper-clad laminate, the adhesive layer having improved heat and humidity resistance provides high reliability and high reliability. There is an advantage that it becomes a high quality copper-clad laminate.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a copper-clad laminate of the present invention.

Claims (6)

[Claims] 1. An adhesive composition containing an epoxy resin, an elastomer having a carboxyl group, a curing agent, and a curing accelerator, wherein the curing accelerator includes the following components (A) and (B): An adhesive composition characterized by using a mixture of components). (A) Imidazole derivatives. (B) At least one of an aromatic carboxylic acid and an acid anhydride. 2. The adhesive composition according to claim 1, wherein the aromatic carboxylic acid as the component (B) is represented by the following general formula (1). Embedded image 3. The imidazole derivative of the component (A),
3. The adhesive composition according to claim 1, which is represented by the following general formula (2). Embedded image 4. The method according to claim 1, wherein the mixing ratio by weight of the component (A) and the component (B) is set in a range of A / B = 1/10 to 1 / 0.1. An adhesive composition according to claim 1. 5. The method according to claim 1, wherein the epoxy resin is reacted with an elastomer having a carboxyl group in advance.
The adhesive composition according to any one of items 4 to 5. 6. A copper-clad laminate comprising an insulating film, an adhesive layer formed on the surface thereof, and a copper foil formed via the adhesive layer, wherein the adhesive layer is Item 6. A copper-clad laminate comprising the adhesive composition according to any one of Items 1 to 5.