JP2001234153A - Adhesive composition for flexible printed circuit board and flexible printed circuit board prepared by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive composition for flexible printed circuit boards which is highly flame-retardant and excellent in flexural reliability. SOLUTION: This adhesive composition contains a polyhedral metal hydroxide represented by the generic formula (1): M1-XQX(OH)2 [wherein M is at least one kind of a metal atom selected from among Mg, Ca, Sn, and Ti; Q is at least one kind of a metal atom selected from among Mn, Fe, Co, Ni, Cu, and Zn; and X is 0.01-0.5].

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive composition for flexible printed circuit boards having excellent flame retardancy and excellent bending reliability, and to a substrate for flexible printed circuit boards using the same.

[0002]

2. Description of the Related Art In recent years, the development of the electronics field has been remarkable.
The demand for flexible printed circuit boards, which are lightweight and capable of three-dimensional wiring and mounting in a narrow space, is increasing. As a result, as a composite component that withstands repeated bending and provides wiring, cables, and connectors to electronic devices, Its applications are also expanding.

[0003] Further, in the consumer equipment, particularly from the standpoint of safety, there is a strong demand for flame retardancy of the flexible printed circuit board, and a flexible printed circuit board that satisfies not only the bending reliability but also the flame retardancy is required. It has been demanded.

[0004] Usually, the adhesive for flexible printed circuit boards is formed by bonding an insulating layer made of a synthetic resin thin film having electrical insulation and a metal foil treated surface, or forming a metal foil on a wiring board having a pattern formed thereon. The adhesion of a coverlay film for preventing oxidation, insulation and protection of the circuit plays an important role on the glossy surface.

As described above, a high flame retardancy is required for such an adhesive for a flexible printed circuit board. Specifically, a high flame retardant of UL-94-VTM-0 class is required. Is required. In order to satisfy such high flame retardancy, a halogenated epoxy resin or the like has been conventionally used as a flame retardant. However, in recent years, a metal hydroxide has been used in consideration of environmental issues.

[0006]

However, in order to impart a satisfactory flame retardancy to the adhesive for flexible printed circuit boards by adding the metal hydroxide, a large amount of the metal hydroxide is added. For example, conventionally, when aluminum hydroxide was used as the metal hydroxide, it was necessary to mix 67% by weight or more in the adhesive for flexible printed circuit boards.

However, when a large amount of metal hydroxide is blended as described above, the flexibility of the manufactured flexible printed circuit board is reduced due to the large amount of blending, and the bending reliability is impaired. Become.

The present invention has been made in view of such circumstances, and has an adhesive composition for a flexible printed circuit board having high flame retardancy and excellent bending reliability, and a flexible printed circuit using the same. It is an object of the present invention to provide a board base material.

[0009]

In order to achieve the above object, the present invention provides an adhesive composition for a flexible printed circuit board containing a polyhedral metal hydroxide represented by the following general formula (1): The object is the first gist.

[0010]

Embedded image

Further, an insulator layer and a conductor layer are laminated and integrated via an adhesive layer formed of the adhesive composition for a flexible printed circuit board. The substrate is a second gist.

The present inventors have conducted a series of studies in order to obtain an adhesive composition for a flexible printed circuit board, which can impart excellent bending reliability together with excellent flame retardancy. As a result, when a polyhedral metal hydroxide represented by the above general formula (1) is used instead of a conventionally used metal hydroxide such as a hexagonal plate-like or scale-like metal hydroxide, The oxide can provide high flame retardancy even when used in a smaller amount than the above-mentioned conventional metal hydroxide, and as a result, found that good bending reliability is provided, and reached the present invention. did. The reason why the high flame retardancy is exhibited even when the amount of the polyhedral metal hydroxide used is smaller than the amount of the conventional metal hydroxide is considered to be as follows. In other words, the crystal has a crystal habit that is completely different from that of a conventional metal hydroxide crystal, and has a large crystal growth in the thickness direction. Fluidity and processability are improved, and filling properties are also improved. Then, the dispersibility in the adhesive composition becomes good, and the flame retardant function can be sufficiently exhibited.

[0013] When the content of the metal hydroxide is set in a specific range, the balance between flame retardancy and flex reliability is particularly excellent.

The polyhedral metal hydroxide used in the present invention is a metal hydroxide having a hexagonal plate shape as shown in FIG. 2 or a so-called thin flat plate shape such as a scale. It does not have a crystal shape, and has a large crystal growth in the thickness direction (c-axis direction) both vertically and horizontally.
For example, a plate-shaped crystal grows in the thickness direction (c-axis direction) and grows more three-dimensionally and more spherically, for example, a granular crystal shape such as a substantially dodecahedral, substantially octahedral, or substantially tetrahedral shape. And usually a mixture thereof. Of course, in addition to the crystal growth method, the shape of the polyhedron changes due to pulverization or grinding, and the shape can be approximated more three-dimensionally and spherically. FIG. 1 shows an example of a scanning electron micrograph (magnification: 50,000) showing the crystal shape of the polyhedral metal hydroxide.
As described above, in the present invention, by using the metal hydroxide, a small amount compared to a conventional hexagonal plate-like or scale-like one having a flat plate-like crystal shape by using the metal hydroxide. Excellent flame retardancy can be obtained by using.

The polyhedral metal hydroxide used in the present invention will be described in more detail with reference to a substantially octahedral metal hydroxide as an example. That is, an octahedral shape which is an example of the metal hydroxide of the present invention is composed of two parallel upper and lower base surfaces and six outer peripheral pyramid surfaces, and the pyramid surface is an upward inclined surface and a downward inclined surface. Have an octahedral shape alternately arranged.

More specifically, a conventional thin plate-shaped crystal having a flat crystal shape has a hexagonal crystal structure, for example, as shown in FIG.
Upper and lower 2 represented by (00 · 1) plane in the Bravais index
It has a hexagonal prism shape whose outer periphery is surrounded by a base surface 10 of the surface and six square cylinder surfaces 11 belonging to a {10.0} mold surface. And
Since there is little crystal growth in the [001] direction (c-axis direction), it has a thin hexagonal column shape.

On the other hand, as shown in FIG. 4, the polyhedral metal hydroxide used in the present invention has two upper and lower surfaces represented by the (00 · 1) plane due to crystal habit control during crystal growth. Is surrounded by six pyramidal surfaces 13 belonging to a {10 · 1} mold surface. And the pyramidal surface 13
Is an upwardly inclined surface 13a such as a (10 · 1) plane, and (10 · 1) plane.
--1) It has an octahedral shape having a special crystal habit in which the downward inclined surfaces 13b such as surfaces are alternately arranged. Also,
The crystal growth in the c-axis direction is also larger than the conventional one. FIG. 4 shows a plate-like shape, but FIG. 5 shows that the crystal growth in the c-axis direction further progressed and the crystal habit became remarkable and became isotropic. As described above, the polyhedral metal hydroxide of the present invention includes those having a shape close to a regular octahedron. That is, the ratio (major axis diameter / thickness) of the major axis diameter of the basal plane to the thickness between the basal planes is preferably 1 to 9.
7 is more preferable as the upper limit of the ratio between the major axis diameter and the thickness. In the Miller-Bravey index, “1 bar” is indicated as “−1”.

As described above, the polyhedral metal hydroxide used in the present invention has six surfaces surrounding the outer periphery of {10 ·
It can be seen from the following that the pyramidal surface belongs to 1 °. That is, when the metal hydroxide crystal of the present invention is observed with a scanning electron microscope from the c-axis direction,
It exhibits three-fold rotational symmetry with the axis as the axis of rotation. The measured value of lattice constant by powder X-ray diffraction was used (10 ·
1) The calculated value of the angle between the faces and the {10 · 1} mold face is
It is almost the same as the measured value of the angle between planes in the scanning electron microscope observation.

Further, the polyhedral shape used in the present invention is
The metal hydroxide has a (110) plane in powder X-ray diffraction.
Half width B of peak₁₁₀And the half value of the peak of the (001) plane
Width B ₀₀₁And the ratio (B₁₁₀/ B₀₀₁) Is 1.4 or more
You. This indicates that the crystallinity in the c-axis direction is good.
It can be confirmed that the thickness has grown. That is,
In a conventional crystal such as magnesium hydroxide, the c-axis direction
Crystals are not growing, and peak of (001) plane blows
Half width B₀₀₁Also increases. Therefore, (B ₁₁₀/
B₀₀₁) Will be smaller. In contrast, many of the present invention
A facet-shaped metal hydroxide has good crystallinity in the c-axis direction
Therefore, the peak of the (001) plane becomes sharp and narrow,
Width B₀₀₁Is also smaller. Therefore, (B₁₁₀/ B₀₀₁)
The value of becomes large.

[0020]

Next, embodiments of the present invention will be described in detail.

Generally, the adhesive composition for a flexible printed circuit board is obtained by blending various polymer components as main components with other additives. And
The adhesive composition for a flexible printed circuit board of the present invention is obtained by using a specific metal hydroxide in addition to the above components. The adhesive composition for a flexible printed circuit board is usually prepared and used as an adhesive solution in which these components are dissolved in a solvent. Here, the “main component” refers to a main component that substantially constitutes the adhesive composition for a flexible printed circuit board, and does not relate only to the amount of use, but to the physical properties of the entire composition. Significant effect on characteristics.

The polymer component is not particularly limited, and includes various polymer components conventionally used in adhesives for flexible printed circuit boards, such as epoxy resin.

The adhesive composition for a flexible printed circuit board of the present invention will be described by way of an example in which the above epoxy resin is used.

As the epoxy resin, 2 per molecule is used.
A commonly used polyepoxy compound such as a bisphenol A type, a novolak type, a glycidyl ether type or a cycloaliphatic type containing at least two epoxy groups can be used. Among them, bisphenol A type is preferable from the viewpoint of adhesiveness, because it has good wettability with the adherend.

When the above-mentioned epoxy resin is used as a main component, a curing agent is used. The curing agent is not particularly limited as long as it has an effect as an epoxy resin curing agent, and a conventionally known curing agent is used. For example, a novolak resin, an amine resin, an acid anhydride, imidazole, dicyandiamide and the like can be mentioned, and these can be used alone or in combination of two or more. Among them, a phenol novolak resin is particularly preferred as the curing agent from the viewpoint of electrical characteristics.

The amount of the curing agent is preferably set to a ratio of 1/4 to 3/4 equivalent to the epoxy equivalent of the epoxy resin. That is, the compounding amount of the curing agent is
If the amount is less than 1/4 equivalent, the chemical resistance tends to decrease, while if it exceeds 3/4 equivalent, the adhesiveness to the adherend tends to decrease.

[0027] Along with the above components, a flexibility-imparting agent, a curing accelerator and the like can be blended.

Examples of the above-mentioned flexibility imparting agent include acrylonitrile-butadiene rubber containing carboxyl group, acrylic rubber, polyester resin and the like, and these may be used alone or in combination of two or more. It is preferable that the blending amount of the flexibility-imparting agent is set in the range of 15 to 40% by weight based on the total amount of the epoxy resin and the curing agent. That is, if the flexibility-imparting agent exceeds 40% by weight, the chemical resistance tends to decrease, and if it is less than 15% by weight, the adhesion to the adherend tends to decrease.

Examples of the curing accelerator include an imidazole complex of BF ₃ , imidazoles, and triphenylphosphine (TPP).

In order to realize UL94-VTM-0 class flame retardancy, the present invention uses a polyhedral metal hydroxide represented by the following general formula (1).

[0031]

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The above-mentioned metal hydroxide has a polyhedral shape. Such a metal hydroxide having a polyhedral shape can be obtained, for example, by controlling various conditions in the production process of the metal hydroxide. Thus, a metal hydroxide having a desired polyhedral shape, for example, a substantially dodecahedral, substantially octahedral, or substantially tetrahedral shape, having a large crystal growth in the thickness direction (c-axis direction) as well as vertically and horizontally. Can be.

The polyhedral metal hydroxide used in the present invention has, as one example, a polyhedral structure having an approximately octahedral crystal outer shape and an aspect ratio of about 1 to 8, preferably 1 to 8.
7, particularly preferably adjusted to 1 to 4. For example, in the case of M = Mg and Q = Zn in the formula (1), it can be manufactured as follows. That is, first, a zinc nitrate compound is added to an aqueous solution of magnesium hydroxide to prepare a partial metal hydroxide as a raw material. Then, the raw material is fired at a temperature in the range of 800 to 1500 ° C., more preferably in a range of 1000 to 1300 ° C., to produce a metal oxide. This metal oxide is represented by the composition of m (MgO) · n (ZnO), and further includes at least one selected from the group consisting of carboxylic acids, metal salts of carboxylic acids, inorganic acids, and metal salts of inorganic acids. By performing a hydration reaction at a temperature of 40 ° C. or more with vigorous stirring in a system in an aqueous medium coexisting with about 0.1 to 6 mol% with respect to the metal oxide, Mg _1-x Zn _x (OH)
₂ (X is a positive number from 0.01 to 0.5) can be used to produce the polyhedral metal hydroxide of the present invention.

In the above-mentioned production method, the raw materials include not only the partial metal hydroxide obtained by the above-mentioned method, but also, for example, a metal hydroxide obtained by a coprecipitation method, a mixture of magnesium hydroxide and Zn, and magnesium oxide. A mixture of Zn oxide, a mixture of magnesium carbonate and Zn carbonate, and the like can also be used. In addition, stirring during the hydration reaction,
Strong agitation is preferred for improving uniformity and dispersibility, for improving the contact efficiency with carboxylic acid, at least one selected from the group consisting of metal salts of carboxylic acids, inorganic acids and metal salts of inorganic acids, etc. It is even more preferable to use a high shearing agitation. Such stirring is preferably performed, for example, with a rotary blade type stirrer at a peripheral speed of the rotary blade of 5 m / s or more.

The carboxylic acid is not particularly limited, but preferably includes a monocarboxylic acid, an oxycarboxylic acid (oxyacid) and the like. Examples of the monocarboxylic acid include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, acrylic acid, crotonic acid, and the like. Examples of the oxycarboxylic acid (oxyacid) include glycolic acid, Lactic acid, hydroacrylic acid,
α-oxybutyric acid, glyceric acid, salicylic acid, benzoic acid, gallic acid and the like. The metal salt of the carboxylic acid is not particularly limited, but preferably includes magnesium acetate, zinc acetate and the like. The inorganic acid is not particularly limited, but preferably includes nitric acid, hydrochloric acid, and the like. The inorganic acid metal salt is not particularly limited, but preferably includes magnesium nitrate, zinc nitrate and the like.

A typical representative example of the metal hydroxide having the polyhedral shape is Mg _{1 -x} Ni _x (OH)
₂ [0.01 <X <0.5], Mg _1-X Zn _X (OH)
₂ [0.01 <X <0.5] and the like. Examples of commercially available metal hydroxides include, for example, Echomag manufactured by Tateho Chemical Industries.

The polyhedral metal hydroxide preferably has a maximum particle size of 10 μm or less. Particularly preferably, the maximum particle size is 6 μm or less. That is,
If the maximum particle size exceeds 10 μm, a large amount tends to be required to have desired flame retardancy.

The specific surface area of the polyhedral metal hydroxide is preferably in the range of 2.0 to 4.0 m ² / g. The specific surface area of the polyhedral metal hydroxide is measured by a BET adsorption method.

The aspect ratio of the metal hydroxide having the polyhedral shape is usually 1 to 8, preferably 1 to 8.
7, particularly preferably 1-4. Here, the aspect ratio is expressed by the ratio of the major axis to the minor axis of the metal hydroxide.

In the present invention, a conventional thin-plate-shaped metal hydroxide may be used together with the polyhedral metal hydroxide. In this case, it is preferable to set the proportion of the polyhedral metal hydroxide in the whole metal hydroxide (including the conventional thin flat plate) to be 50% by weight or more. That is, if the proportion of the polyhedral metal hydroxide is less than 50% by weight, it is difficult to obtain a sufficient flame-retardant effect by using a small amount.

The content of the polyhedral metal hydroxide is preferably set in the range of 50 to 65% by weight, particularly preferably 55 to 60% by weight, based on the whole adhesive composition for flexible printed circuit boards. It is. That is, when the content of the metal hydroxide is less than 50% by weight,
It is because it becomes difficult to obtain sufficient flame retardancy, and conversely, if it exceeds 65% by weight, the bending reliability tends to decrease.

In the adhesive composition for a flexible printed circuit board of the present invention, in addition to the above-mentioned components, a silane coupling agent and an inorganic filler as an adhesion improver may be used as needed, as long as the object of the present invention is not impaired. Ordinary additives such as antioxidants, heat stabilizers, ultraviolet absorbers, lubricants, mold release agents, coloring agents including dyes and pigments can be appropriately compounded.

The adhesive composition for a flexible printed circuit board of the present invention can be obtained, for example, by blending and mixing the above-mentioned components and other additives as necessary at an appropriate ratio.

When the adhesive composition for a flexible printed circuit board of the present invention is used, it is used as a solution dissolved in a solvent. Examples of the solvent include methyl ethyl ketone, toluene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, dioxane, methyl cellosolve acetate, and the like. These may be used alone or in combination of two or more.

A substrate for a flexible printed circuit board using the adhesive composition for a flexible printed circuit board of the present invention is formed, for example, on an electrically insulating plastic via an adhesive layer formed by the adhesive composition. It is obtained by laminating and integrating an insulator layer such as a film and a conductor layer such as a metal foil.

As the above-mentioned electrically insulating plastic film, polyimide film, polyparabanic acid film,
Examples include a polyester film, a polyethylene naphthalate film, a polyether sulfone film, a polyether imide film, and a polyether ether ketone film.

The metal foil is not particularly limited, and examples thereof include a metal foil having good conductivity such as a copper foil, an aluminum foil and a nichrome foil. Also, the thickness is not particularly limited, and is set appropriately. If necessary, the surface of the metal foil may be plated with tin, solder, gold, nickel or the like.

The substrate for a flexible printed circuit board of the present invention is produced, for example, as follows. That is, first, each component constituting the adhesive composition for a flexible printed circuit board is mixed with a resin solid content concentration of 20 to 50.
% To prepare an adhesive solution by stirring and dissolving in the solvent. After preparation, reverse coater,
Using a comma coater or the like, it is applied in a dry state to a thickness of 10 to 50 μm on the surface of the electrically insulating film or the metal foil. Then, the solvent is volatilized by drying at 50 to 150 ° C. for 1 to 10 minutes to produce an electrically insulating film having an adhesive layer formed thereon or a metal foil having an adhesive layer formed thereon in a B-stage state.

Next, a metal foil (or an electrically insulating film) is placed on the adhesive layer-forming surface of the above-mentioned electrically insulating film (or an adhesive layer-formed metal foil) on which the adhesive layer has been formed by a batch press method or a continuous pressing method. The substrate for a flexible printed circuit board is manufactured by heat-pressing by a roll laminating method and performing after-curing as necessary.

The conditions for carrying out the continuous roll laminating method include a temperature of 80 to 150 ° C. and a linear pressure of 9.8 to 490 N /
cm and a speed in the range of 1 to 10 m / min are suitable. Also,
Suitable after-curing conditions are a temperature of 80 to 150 ° C. and a time of 1 to 24 hours.

The conditions for heat-pressing the electrically insulating film with an adhesive obtained by the method described above as a coverlay film on a metal foil surface on which a circuit pattern is formed are as follows: Temperature, 80 to 150 ° C, pressure 196 × 10 ^{4 to} 980 × 10
It is preferable to set the conditions in the range of ⁴ Pa and the time of 1 to 60 minutes.

Next, examples will be described together with comparative examples.

The following components were prepared.

[Epoxy resin] Epiclon 900 (manufactured by Dainippon Ink), molecular weight 23,000

[Phenol novolak resin] Tamanol P-180 (manufactured by Arakawa Chemical Co., Ltd.)

[Flexibility-imparting agent] Nipol-1072
(Manufactured by Zeon Corporation)

[Curing accelerator] 2-methylimidazole (manufactured by Shikoku Chemicals)

[Flame Retardants A to F] Each of the flame retardants A to F shown in Table 1 below was prepared. The polyhedral metal hydroxides A to C in Table 1 below were prepared according to the above-described method for producing a polyhedral metal hydroxide.

[0059]

[Table 1]

[0060]

Examples 1 to 5 and Comparative Examples 1 to 3 The components shown in Tables 2 and 3 below were added to 249 parts of methyl ethyl ketone so as to have the proportions shown in the same table, and dissolved and dispersed by stirring. Was prepared as an adhesive solution for flexible printed circuit boards.

Then, the above adhesive solution was applied to the surface of a polyester film having a thickness of 25 μm with a reverse coater so as to have a thickness of 15 μm after drying, and dried in a hot air circulating drier at 100 ° C. for 3 minutes for bonding. A polyester film on which an agent layer was formed was obtained.

Thereafter, the surface on which the adhesive layer is to be formed and the thickness of 35 μm
Rolled copper foil processing surface (for example, nickel-copper alloy processing)
And a roll laminator under the conditions of a roll temperature of 90 ° C., a roll pressure of 29.4 N / cm, and a speed of 5 m / min.
After-curing for 24 hours in a hot air circulating dryer
A substrate for a flexible printed circuit board was obtained.

A cover lay film to be bonded to the glossy side of the substrate was dried in the same manner as the substrate, applied to a thickness of 25 μm, and manufactured under the same drying conditions.
Then, the glossy side of the base material and the adhesive layer of the coverlay film are overlapped so as to be in contact with each other.
Bonding was performed using a hot press under the conditions of ° C., a pressure of 784 × 10 ⁴ Pa, and a time of 2 minutes. Thus, a flexible printed circuit board was obtained.

[0064]

[Table 2]

[0065]

[Table 3]

The flexible printed circuit boards obtained in the examples and the comparative examples thus obtained were subjected to various characteristic tests (flame retardancy and bending reliability) and evaluated. The results are shown in Tables 4 and 5 below.

[Flame Retardancy] Using each of the obtained flexible printed circuit boards, an evaluation test for flame retardancy was conducted in accordance with UL-94.

[Bending reliability] Each flexible printed circuit board was subjected to JPCA-BM02 in a normal state (23 ° C).
The test was performed in accordance with. Then, the number of disconnections at a radius of curvature of 3 mm was measured. As a result, evaluation was made as follows. That is, の も の indicates the case of 1 × 10 ⁷ times or more, and × indicates the case of less than 1 × 10 ⁷ times.

[0069]

[Table 4]

[0070]

[Table 5]

From the results in Tables 4 and 5, Comparative Example 1 was obtained.
The product was set to the same blending amount as that of the products of Examples 1 to 3, and there was no problem regarding the bending reliability, but the flame retardancy was poor due to the small blending amount. The product of Comparative Example 2 was also set to the same amount as the product of Example 1 in the same manner as the product of Comparative Example 1, and there was no problem with respect to the bending reliability. I was The product of Comparative Example 3 had sufficient flame retardancy, but was inferior in bending reliability due to the large amount of the compounding agent. On the other hand, in the example product, the mixing amount was set to be smaller than that of the conventionally used metal hydroxide, but sufficient flame retardancy was obtained, and there was no problem regarding the bending reliability. .

[0072]

As described above, the present invention is an adhesive composition for a flexible printed circuit board containing a metal hydroxide having a polyhedral shape represented by the general formula (1). A flexible printed circuit board base material obtained by laminating and integrating an insulator layer and a conductor layer via an adhesive layer formed as described above. For this reason, it shows high flame retardancy even if it is used in a smaller amount than the above-mentioned conventionally used metal hydroxide. Excellent bending reliability is obtained without generation. Therefore, the base material for a flexible printed circuit board of the present invention is particularly useful for the base material of a flexible printed circuit board whose demand has been increasing in recent years, and has extremely high industrial value.

When the content of the metal hydroxide is set in a specific range, the balance between flame retardancy and bending reliability is particularly excellent.

[Brief description of the drawings]

FIG. 1 is a scanning electron micrograph (magnification: 5) showing an example of the crystal shape of a polyhedral metal hydroxide used in the present invention.
0000 times).

FIG. 2 is a perspective view showing a hexagonal plate-like shape which is one of the crystal shapes of a conventional metal hydroxide.

FIGS. 3A and 3B are explanatory views showing the outer shape of a conventional metal hydroxide, wherein FIG. 3A is a plan view and FIG. 3B is a side view.

FIG. 4 is an explanatory view showing an example of the outer shape of the metal hydroxide of the present invention, wherein (a) is a plan view and (b) is a side view.

FIG. 5 is an explanatory view showing another example of the outer shape of the metal hydroxide of the present invention, wherein (a) is a plan view and (b) is a side view.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Teruhiko Akimoto 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation (72) Inventor Tetsuya Terada 1-1-2 Shimohozumi, Ibaraki-shi, Osaka Inside Nitto Denko (72) Inventor Toshihiko Sugimoto 1-1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Inside Nitto Denko Corporation (72) Inventor Yutaka Aoki 1-1-2 Shimohozumi, Ibaraki City, Osaka Nitto Denko F-term within the company (reference) 4F100 AA17A AA18A AA21A AA23A AA24A AA25A AA28A AB01C AB17 AB33 AK01B AK41 AK53A AR00B AR00C BA03 BA07 BA10B BA10C CA23A CB00A GB43 JG01C JG04 HAJ1J07 KA07 EC01

Claims (4)

[Claims] 1. An adhesive composition for a flexible printed circuit board, comprising a polyhedral metal hydroxide represented by the following general formula (1). Embedded image 2. The adhesive composition for a flexible printed circuit board according to claim 1, wherein the main component of the adhesive composition for a flexible printed circuit board is an epoxy resin. 3. The content of the polyhedral metal hydroxide represented by the general formula (1) is set in the range of 50 to 65% by weight in the whole adhesive composition for a flexible printed circuit board. The adhesive composition for a flexible printed circuit board according to claim 1 or 2. 4. An insulating layer and a conductor layer are laminated and integrated via an adhesive layer formed by the adhesive composition for a flexible printed circuit board according to any one of claims 1 to 3. A base material for a flexible printed circuit board, wherein the base material is formed.