JP2007238707A - Epoxy-based adhesive, coverlay, prepreg, metal-clad laminated plate and printed circuit substrate plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an epoxy-based adhesive having both excellent flexibility and high electric insulation jointly, and a coverlay, prepreg, metal-clad laminated plate and printed circuit substrate plate by using the same. <P>SOLUTION: This epoxy-base adhesive is obtained by adding ≥10 and ≤50 pts.mass carboxy group-modified rubber to 100 pts.mass base resin containing a modified bisphenol A type epoxy resin introduced with a flexible back bone through a low polar bonding group, and a curing agent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an epoxy adhesive excellent in electrical insulation and flexibility, and a coverlay, prepreg, metal-clad laminate, and printed wiring board using the epoxy adhesive.

In the field of electronic materials, epoxy adhesives are widely used as insulating materials in applications of printed circuit boards such as flexible printed circuit boards (hereinafter abbreviated as “FPC”).
However, the epoxy adhesive does not sufficiently satisfy the performance required for FPC in terms of the flexibility (flexibility) of the adhesive layer after curing and the adhesion with a metal layer (for example, copper foil). It was.

Therefore, as an adhesive for FPC use, an epoxy adhesive added with an elastomer (rubber component) is used in order to improve the above-described flexibility and adhesion.
As the elastomer, carboxylated NBR (NBR represents acrylonitrile butadiene rubber), acrylic rubber, and the like are used.

  As such an adhesive, for example, a thermosetting epoxy resin adhesive composed of an epoxy resin, an aromatic amine, an acrylonitrile copolymer having a carboxy group at its terminal, and a tertiary amine or imidazole compound is proposed. (For example, refer to Patent Document 1).

  Also obtained by addition reaction of a polyfunctional epoxy resin containing two or more epoxy groups in one molecule, and a modified polyphenol obtained by acetalizing a polyphenol with a polyvalent vinyl ether. An epoxy resin composition containing a modified epoxy resin and a curing agent as essential components has been proposed (see, for example, Patent Document 2).

Further, a modified epoxy resin containing an epoxy resin and a curing agent, and the epoxy resin is obtained by glycidyl ether-modified polyphenols obtained by acetalizing a polyhydric phenol and a polyvalent vinyl ether; An epoxy resin composition obtained by addition reaction with polyhydric phenols has been proposed (see, for example, Patent Document 3).
JP-A-62-199627 JP 2005-29634 A JP-A-2005-187609

  However, when a large amount of these rubber components is added to achieve higher flexibility, there is a problem that the electrical insulation of the adhesive layer after curing is lowered due to the influence of ionic impurities contained in the rubber components. there were.

  The present invention has been made in view of the above circumstances, and an epoxy adhesive having both excellent flexibility and high electrical insulation, and a cover lay, a prepreg, and a metal-clad laminate using the epoxy adhesive An object of the present invention is to provide a printed wiring board.

  The epoxy adhesive according to claim 1 of the present invention is a carboxy group-modified resin in 100 parts by mass of a base resin containing a modified bisphenol A type epoxy resin having a flexible skeleton introduced through a low-polar bonding group and a curing agent. It is characterized by adding 10 to 50 parts by mass of rubber.

  The epoxy adhesive according to a second aspect of the present invention is the epoxy adhesive according to the first aspect, wherein the carboxy group-modified rubber comprises a carboxylated acrylonitrile butadiene rubber and a carboxylated ethylene-acrylic rubber, and the carboxyl relative to the carboxylated acrylonitrile butadiene rubber. The blending ratio of the fluorinated ethylene-acrylic rubber is characterized by being 20 to 80% (by mass ratio).

  The cover lay according to claim 3 of the present invention is a cover lay in which an adhesive layer is provided on one side of an insulating film, wherein the adhesive constituting the adhesive layer has a flexible skeleton via a low-polarity bonding group. A carboxy group-modified rubber is added in an amount of 10 to 50 parts by mass to 100 parts by mass of the base resin containing the introduced modified bisphenol A type epoxy resin and a curing agent.

  The prepreg according to claim 4 of the present invention is a prepreg obtained by impregnating a glass cloth with an epoxy adhesive, wherein the epoxy adhesive is a modified bisphenol A type in which a flexible skeleton is introduced through a low-polar bonding group. A carboxy group-modified rubber is added to 10 to 50 parts by mass to 100 parts by mass of a base resin containing an epoxy resin and a curing agent.

  The metal-clad laminate according to claim 5 of the present invention is a metal-clad laminate in which an adhesive layer is provided between a base film and a metal foil, and the adhesive constituting the adhesive layer has a low polarity bond. A carboxy group-modified rubber is added in an amount of 10 to 50 parts by mass to 100 parts by mass of a base resin containing a modified bisphenol A type epoxy resin having a flexible skeleton introduced through a group and a curing agent. Features.

  A printed wiring board according to claim 6 of the present invention is characterized in that the coverlay according to claim 3 of the present invention is bonded to the metal foil surface of the metal-clad laminate according to claim 5 of the present invention. And

The epoxy adhesive of the present invention is prepared by adding 10 parts by mass of a carboxy group-modified rubber to 100 parts by mass of a base resin containing a modified bisphenol A type epoxy resin having a flexible skeleton introduced through a low-polar bonding group and a curing agent. As mentioned above, since 50 mass parts or less are added, it shows the outstanding softness | flexibility and high electrical insulation. Therefore, when this epoxy adhesive is applied to coverlays, prepregs, metal-clad laminates and printed wiring boards for electronic devices, coverlays, prepregs, metal-clad laminates and printed wiring boards that are excellent in flexibility and electrical insulation. Is obtained.
Therefore, according to the epoxy-based adhesive of the present invention, it is possible to provide a printed wiring board such as an FPC that requires a narrow pitch wiring. As a result, downsizing, high functionality and long life of various electronic devices are achieved. It can contribute to the conversion.

  Hereinafter, the present invention will be described in detail.

  The epoxy adhesive of the present invention is prepared by adding 10 parts by mass of a carboxy group-modified rubber to 100 parts by mass of a base resin containing a modified bisphenol A type epoxy resin having a flexible skeleton introduced through a low-polar bonding group and a curing agent. As mentioned above, 50 mass parts or less are added.

If the carboxy group-modified rubber is less than 10 parts by mass with respect to 100 parts by mass of the base resin, the flexibility (flexibility) of the adhesive layer formed using this epoxy adhesive cannot be sufficiently obtained. On the other hand, when the carboxy group-modified rubber exceeds 50 parts by mass with respect to 100 parts by mass of the base resin, the electrical resistance value of the adhesive layer formed using this epoxy adhesive decreases, and sufficient insulation is obtained. I can't.
By setting the amount of rubber to be in the above range, an adhesive layer excellent in both flexibility (flexibility) and insulation can be formed.

  The carboxy group-modified rubber is composed of a carboxylated acrylonitrile butadiene rubber (carboxylated NBR) and a carboxylated ethylene-acrylic rubber, and the compounding ratio of the carboxylated ethylene-acrylic rubber to the carboxylated NBR is 20 to 80 (by mass ratio). % Is preferred.

  If the compounding ratio of the carboxylated ethylene-acrylic rubber to the carboxylated NBR is less than 20% (by mass ratio), the migration resistance of the epoxy adhesive is lowered. On the other hand, when the blending ratio of the carboxylated ethylene-acrylic rubber to the carboxylated NBR exceeds 80% (by mass ratio), the flow distance after applying the epoxy adhesive increases.

  Examples of the modified bisphenol A type epoxy resin into which a flexible skeleton is introduced through a low polar bonding group include EPICLON EXA-4850-150 (Dainippon Ink Chemical Co., Ltd.).

As the curing agent, any curing agent can be used without particular limitation as long as it can be used for curing an epoxy resin. For example, an aliphatic amine curing agent, an alicyclic amine curing agent, a secondary or Tertiary amine-based curing agents, aromatic amine-based curing agents, acid anhydride-based curing agents, dicyandiamide, boron trifluoride amine complex salts, imidazole compounds, phenol resins and the like can be mentioned. These may be used alone or in combination of two or more.
Further, the blending amount of the curing agent is determined according to the epoxy resin, and is appropriately adjusted according to molding conditions, characteristics, and the like within a range in which the curing agent is normally used.

Carboxylated NBR is an elastomer obtained by NBR modification, which is a copolymer of acrylonitrile and butadiene, and introducing a boxy group.
Examples of carboxylated NBR include Nipol 1072 (manufactured by Nippon Zeon Co., Ltd.).
As a method for introducing a carboxy group into NBR, (1) a method in which acrylonitrile and butadiene are copolymerized, a monomer having a carboxy group is further copolymerized; and (2) after acrylonitrile and butadiene are copolymerized, Examples thereof include a method of graft-reacting a monomer having a carboxy group.

Carboxylated ethylene-acrylic rubber is an elastomer obtained by modifying ethylene-acrylic rubber, which is a copolymer of ethylene and acrylic, to introduce a carboxy group.
Examples of the carboxylated ethylene-acrylic rubber include Baymac HVG (manufactured by Mitsui DuPont Polychemical Co., Ltd.).
As a method for introducing a carboxy group into ethylene-acrylic rubber, (1) a method of copolymerizing a monomer having a carboxy group when ethylene and acrylic are copolymerized, and (2) a copolymer of ethylene and acrylic. Then, the method etc. which carry out the graft reaction of the monomer which has a carboxy group are mentioned.

Moreover, you may mix | blend a filler, a flame retardant, another additive, etc. with the epoxy adhesive of this invention as needed.
Examples of the filler include silica, mica, clay, talc, titanium oxide, calcium carbonate and the like.

  As the flame retardant, generally known ones can be used without limitation. For example, inorganic hydroxides such as aluminum hydroxide, magnesium hydroxide, antimony trioxide, inorganic oxides, phosphate ester flame retardants And halogen-containing phosphoric ester-based flame retardants, inorganic bromine-based flame retardants, organic bromine-based flame retardants, and organic chlorine-based flame retardants. These may be used alone or in combination of two or more.

  Examples of other additives include a silane coupling agent and imidazole that are used to improve the adhesion to the circuit.

Next, the usage method of the epoxy adhesive of this invention is demonstrated.
Examples of the method of using the epoxy adhesive of the present invention include constituent materials such as a modified bisphenol A type epoxy resin into which a flexible skeleton is introduced via a low-polar bonding group, a curing agent, carboxylated NBR, and carboxylated ethylene-acrylic rubber. And an organic solvent are mixed in a predetermined amount, and an adhesive solution is prepared by stirring and mixing using a pot mill, a ball mill, a homogenizer, a super mill or the like, and this adhesive solution is applied to an object.

  The epoxy adhesive of the present invention can be used to bond or seal an object by applying the above adhesive solution to the object, and drying and curing. The adhesive composition can be dried and cured at a temperature of about 20 to 200 ° C., for example.

  Examples of the organic solvent used for preparing the adhesive solution include methanol, acetone, methyl ethyl ketone, toluene, dimethylformamide, 2-methoxyethanol and the like. The solid content concentration in the adhesive solution is preferably in the range of 5 to 70% by mass, more preferably in the range of 10 to 50% by mass in consideration of the suppression of coating unevenness and the solubility of the adhesive. Is within.

  The epoxy-based adhesive of the present invention can be suitably used for various applications, but exhibits excellent effects when applied to various materials used for flexible printed circuit boards (FPC). Examples of the FPC material include metal clad laminates such as coverlay (CL) and copper foil clad laminate (CCL), printed wiring boards, and the like.

FIG. 1 is a schematic cross-sectional view showing an embodiment of a cover lay of the present invention.
The cover lay 1 of this embodiment is formed by providing an adhesive layer 3 made of the epoxy adhesive of the present invention on one surface 2a of an insulating film (film base material) 2. In a flexible printed circuit board, It is used to insulate and protect the circuit or the like by being laminated on the circuit or the like formed on the substrate.

As the insulating film 2, for example, a film made of polyimide resin, polyethylene terephthalate resin or the like and having a thickness of about 10 μm to 150 μm can be used.
The thickness (after drying) of the adhesive layer 3 can be set to, for example, about 1 μm to 100 μm.
As described above, the method of forming the adhesive layer from the epoxy adhesive of the present invention can be performed by a method such as coating.

  The CCL to which the cover lay of the present invention is applied is not particularly limited. For example, a three-layer CCL formed by bonding a copper foil (metal foil) with an adhesive to a base film made of polyimide or the like. A two-layer CCL (CCL having no adhesive layer) formed by applying a polyimide varnish to one side of a copper foil (metal foil) and drying can be used.

According to the cover lay of the present invention, since the adhesive layer is formed by the epoxy adhesive of the present invention, it has excellent flexibility and high electrical insulation when applied to a printed wiring board for electronic equipment. Show.
Therefore, according to the coverlay of the present invention, since the insulation resistance is improved, it is possible to provide a printed wiring board such as an FPC which requires a narrow pitch wiring. As a result, it is possible to contribute to miniaturization, high functionality, and long life of various electronic devices. Moreover, since the coverlay of this invention has flexibility, if this is applied to a printed wiring board, a printed wiring board will also have flexibility.

  Moreover, the epoxy adhesive of this invention can form a prepreg by making glass cloth impregnate. This prepreg is provided between a base film and a metal foil in a metal-clad laminate, and is used as an adhesive that constitutes an adhesive layer that bonds the two together.

  The glass cloth is not particularly limited, and examples thereof include an MS cloth manufactured by Asahi Schwer.

According to the prepreg of the present invention, since the glass cloth is impregnated with the epoxy adhesive of the present invention, it exhibits excellent flexibility and high electrical insulation.
Therefore, according to the prepreg of the present invention, it is possible to provide a printed wiring board such as an FPC that requires a narrow pitch wiring. As a result, it is possible to contribute to miniaturization, high functionality, and long life of various electronic devices. Moreover, since this prepreg has flexibility, if this is applied to a printed wiring board, a printed wiring board will also have flexibility.

FIG. 2 is a schematic cross-sectional view showing an embodiment of the metal-clad laminate of the present invention.
In the metal-clad laminate 4 of this embodiment, the adhesive layer 6 made of the prepreg is provided between the base film 5 and the metal foil 7.

As the base film 5, a resin film having electrical insulation and flexibility is used, and examples thereof include films made of resins such as polyimide, aramid, polyethylene terephthalate, polybutylene terephthalate, polyamide, polycarbonate, and polyethersulfone. .
The metal foil 7 is made of copper foil or the like and forms a predetermined circuit pattern.

According to the metal-clad laminate of the present invention, since the adhesive layer made of the above prepreg is provided between the base film and the metal foil, it has excellent flexibility and high electrical insulation. Show.
Therefore, according to the metal-clad laminate of the present invention, it is possible to provide a printed wiring board such as an FPC that requires a narrow pitch wiring. As a result, it is possible to contribute to miniaturization, high functionality, and long life of various electronic devices. In addition, since the metal-clad laminate of the present invention has flexibility, when this is applied to a printed wiring board, the printed wiring board also has flexibility.

FIG. 3 is a schematic cross-sectional view showing an embodiment of the printed wiring board of the present invention.
In the printed wiring board 10 of this embodiment, the cover lay 1 is attached to the surface (metal foil surface) on which the metal foil 7 of the metal-clad laminate 4 is provided, and the cover lay 1 and the metal-clad laminate 4 Are laminated and integrated.

The printed wiring board 10 can be manufactured by a method in which, for example, the metal foil 7 of the metal-clad laminate 4 is etched to form a wiring, and then the coverlay 1 is attached to the metal foil surface. .
The cover lay 1 is attached so that the adhesive layer 3 of the cover lay 1 and the metal foil surface of the metal-clad laminate 4 face each other and are integrated by hot pressing or the like. As hot press conditions, for example, the heating temperature can be about 140 to 200 ° C. and the heating time can be about 0.1 to 3 hours.

According to the printed wiring board of the present invention, the cover lay of the present invention is adhered to the surface of the metal-clad laminate of the present invention on which the metal foil 7 is provided, and the cover lay of the present invention and the metal tension of the present invention are adhered. Since the laminated board is laminated and integrated, it exhibits excellent flexibility and high electrical insulation.
Therefore, according to the printed wiring board of the present invention, it is possible to provide a printed wiring board such as an FPC requiring a narrow pitch wiring. As a result, it is possible to contribute to miniaturization, high functionality, and long life of various electronic devices. In addition, the printed wiring board of the present invention has flexibility because the coverlay having flexibility and the metal-clad laminate are laminated and integrated.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.

[Preparation of epoxy adhesive]
(Example)
Epoxy adhesives according to the examples were prepared according to the formulations shown in Tables 1 and 2. In addition, in each table | surface, the compounding ratio was represented by the mass part which made base resin alpha which contains a hardening | curing agent in an epoxy resin 100 mass parts.
In addition, the compounding ratio of the epoxy resin and the curing agent in the base resin α was set to epoxy resin: curing agent = 88 mass%: 12 mass%.
An epoxy resin, a curing agent, and carboxylated ethylene-acrylic rubber and carboxylated NBR are dissolved and dispersed in methyl ethyl ketone, and the solid content (base resin α, carboxylated ethylene-acrylic rubber and carboxylated NBR) is 30% by mass. An adhesive solution was prepared.
Modified bisphenol A type epoxy resin (manufactured by Dainippon Ink & Chemicals, trade name: EPICLON EXA-4850-150) having a flexible skeleton introduced through a low-polar bonding group as an epoxy resin, and 4,4′- as a curing agent Diaminodiphenyl sulfone (manufactured by Wako Pure Chemical Industries, reagent special grade), Baymac HVG (manufactured by Mitsui DuPont Polychemical Co., Ltd.) as carboxylated ethylene-acrylic rubber, and Nipol 1072 (manufactured by Nippon Zeon Co., Ltd.) as carboxylated NBR were used.

(Comparative example)
An epoxy adhesive according to a comparative example was prepared according to the formulation shown in Table 3. In addition, in each table | surface, the compounding ratio was represented by the mass part which made 100 mass parts base resin (beta) which contains a hardening | curing agent in an epoxy resin.
In addition, the compounding ratio of the epoxy resin and the curing agent in the base resin β was set to epoxy resin: curing agent = 77 mass%: 23 mass%.
An epoxy resin, a curing agent, and carboxylated ethylene-acrylic rubber, or carboxylated ethylene-acrylic rubber and carboxylated NBR are dissolved and dispersed in methyl ethyl ketone to obtain a solid content (base resin β and carboxylated ethylene- An adhesive solution having an acrylic rubber or carboxylated ethylene-acrylic rubber and carboxylated NBR) concentration of 30% by mass was prepared.
Bisphenol A type epoxy resin (product name: Epicoat 828EL) as an epoxy resin, 4,4'-diaminodiphenylsulfone (made by Wako Pure Chemical Industries, reagent special grade) as a curing agent, carboxylated ethylene-acrylic rubber Baymac HVG (manufactured by Mitsui DuPont Polychemical Co., Ltd.) and Nipol 1072 (manufactured by Nippon Zeon Co., Ltd.) were used as carboxylated NBR.

[Evaluation of repulsive force]
The adhesive solution of each example or each comparative example was applied to a 25 μm thick polyimide film (trade name: Kapton 100H, manufactured by Toray DuPont Co., Ltd.) so that the thickness after drying was 25 μm. Dried to form an adhesive layer.
Next, another polyimide film with a thickness of 25 μm is bonded to the adhesive layer formed on this polyimide film, and pressed for 40 minutes at 170 ° C. and a pressure of 40 kg / cm ² , and two polyimide films are passed through the adhesive. Was obtained.
Thereafter, the laminated film was formed into a strip shape having a width of 20 mm and a length of 100 mm, and both ends of the strip in the longitudinal direction were overlapped with each other to produce a ring-shaped sample having a diameter of about 30 mm.
Subsequently, this ring-shaped sample was compressed with a tensile compression tester (TG-200N, manufactured by Minebea Co., Ltd.), and the repulsive force (gf) of the ring-shaped sample when compressed to a diameter of 10 mm was measured. This value was used as the actual measurement value of the sample.
Next, the thickness of the sample (laminated film) from which the repulsive force was measured was measured, and the value (converted value) converted by the following formula (1) was defined as the repulsive force (gf) of this sample.

The results are shown in Tables 1 to 3.
In addition, the thing with a repulsive force (converted value) of less than 20 gf was passed, and the thing with a repulsive force (converted value) of 20 gf or more was rejected.

[Measurement of insulation resistance]
The adhesive solution of each example or each comparative example was applied to a polyimide film having a thickness of 25 μm (trade name: Kapton 100H, manufactured by Toray DuPont Co., Ltd.) so that the thickness after drying was 10 μm. Dried to form an adhesive layer.
Next, a rolled copper foil having a thickness of 18 μm was adhered to the adhesive surface of the adhesive layer formed on the polyimide film to obtain a single-sided plate.
Next, a copper circuit pattern as shown in FIG. 4 was formed on the copper foil of this single-sided plate. The unit of the dimension shown in FIG. 4 is μm.
Next, an adhesive solution is applied to another polyimide film having a thickness of 25 μm (trade name: Kapton 100H, manufactured by Toray DuPont Co., Ltd.) so that the thickness after drying is 25 μm, and this adhesive solution is dried to obtain an adhesive. A layer was formed.
Next, the adhesive layer formed on the polyimide film is bonded to the adhesive surface of the single-sided board on which the copper circuit pattern is formed, and pressed at 170 ° C. and a pressure of 40 kg / cm ^{2 for} 40 minutes to measure insulation resistance. Printed wiring board γ was prepared.
In the normal state, a DC voltage of 500 V was applied to the printed wiring board γ and held for 1 minute, and the insulation resistance between the copper circuit patterns shown in FIG. 4 was measured.
The results are shown in Tables 1 to 3.
A sample having an insulation resistance of 10 ¹¹ Ω or higher was accepted, and a sample having an insulation resistance of less than 10 ¹¹ Ω was rejected.

[Evaluation of migration resistance]
The adhesive solution of each example or each comparative example was applied to a polyimide film having a thickness of 25 μm (trade name: Kapton 100H, manufactured by Toray DuPont Co., Ltd.) so that the thickness after drying was 10 μm. Dried to form an adhesive layer.
Next, a rolled copper foil having a thickness of 18 μm was adhered to the adhesive surface of the adhesive layer formed on the polyimide film to obtain a single-sided plate.
Next, a comb-shaped copper circuit pattern with a line pitch of 100 μm was formed on the copper foil of this single-sided plate.
Next, an adhesive solution is applied to another polyimide film having a thickness of 25 μm (trade name: Kapton 100H, manufactured by Toray Du Pont Co., Ltd.) so that the thickness after drying becomes 30 μm, and this adhesive solution is dried to obtain an adhesive. A layer was formed.
Next, the adhesive layer formed on the polyimide film is bonded to the adhesive surface of the single-sided plate on which the copper circuit pattern is formed, and pressed at 170 ° C. and a pressure of 40 kg / cm ^{2 for} 40 minutes, and is resistant to migration. A printed wiring board δ for evaluation was produced.
The printed wiring board δ produced as described above was used to evaluate migration resistance (presence of dendrite generation).
As test conditions, a DC voltage of 50 V was applied between the electrodes in an atmosphere of 85 ° C. and 85% RH (relative humidity), and the insulation resistance between the electrodes was measured by holding for 250 hours.
The migration resistance was evaluated by observing the printed wiring board δ with an optical microscope.
In addition, the case where dendrite did not generate | occur | produce at all was evaluated as the pass ((circle)), and the case where dendrite had generate | occur | produced as unacceptable (x).
The results are shown in Tables 1 to 3.

[Evaluation of adhesive flow distance]
The adhesive solution of each example or each comparative example was applied to a polyimide film having a thickness of 25 μm (trade name: Kapton 100H, manufactured by Toray DuPont Co., Ltd.) so that the thickness after drying was 30 μm. Dried to form an adhesive layer.
Subsequently, ten punch holes with a diameter of 5 mm were formed through the adhesive layer and the polyimide film in the thickness direction.
Next, a rolled copper foil having a thickness of 18 μm was attached to the adhesive surface of the adhesive layer formed on the polyimide film, and pressed at 170 ° C. and a pressure of 40 kg / cm ^{2 for} 40 minutes.
After pressing, the maximum leaching distance of the adhesive into the punch holes was measured at all 10 locations for each punch hole, and the average distance of 10 locations was defined as the “adhesive flow distance”.
In addition, when the adhesive flow distance was less than 0.50 mm, it was evaluated that the adhesive flow characteristics were excellent.
The results are shown in Tables 1 to 3.

  From the results of Table 1 and Table 2, in Examples 1 to 9, the epoxy adhesive contains a modified bisphenol A type epoxy resin having a flexible skeleton introduced through a low-polar bonding group and a curing agent. Since 100 parts by mass of carboxy group-modified rubber composed of carboxylated acrylonitrile butadiene rubber and carboxylated ethylene-acrylic rubber is added in an amount of 10 parts by weight to 50 parts by weight, excellent flexibility and high electrical insulation It was confirmed that Furthermore, in Examples 3 to 9, since the compounding ratio of the carboxylated ethylene-acrylic rubber to the carboxylated acrylonitrile butadiene rubber is 20 to 80% (by mass ratio), it is excellent in migration resistance and adhesive flowability. It was confirmed.

From the results of Table 3, in Comparative Example 1, 50 parts by mass of a carboxy group-modified rubber composed of carboxylated acrylonitrile butadiene rubber and carboxylated ethylene-acrylic rubber is added to 100 parts by mass of the base resin. Since the bisphenol A type epoxy resin was used without using the modified bisphenol A type epoxy resin in which a flexible skeleton was introduced via a low polar bonding group as the epoxy resin, the flexibility was insufficient.
In Comparative Example 2, although a modified bisphenol A type epoxy resin having a flexible skeleton introduced through a low-polar bonding group is used as an epoxy resin, only carboxylated ethylene-acrylic rubber is used with respect to 100 parts by mass of the base resin. Since 10 parts by mass was added, the adhesive flowability was poor.
In Comparative Example 3, although a modified bisphenol A type epoxy resin having a flexible skeleton introduced through a low-polar bonding group is used as an epoxy resin, carboxylated acrylonitrile butadiene rubber and carboxylated ethylene are used with respect to 100 parts by weight of the base resin. -Since only 7 parts by weight of carboxy group-modified rubber composed of acrylic rubber was added, flexibility was insufficient.
In Comparative Example 4, although a modified bisphenol A type epoxy resin having a flexible skeleton introduced through a low-polar bonding group is used as an epoxy resin, carboxylated acrylonitrile butadiene rubber and carboxylated ethylene are used with respect to 100 parts by weight of the base resin. -Since 55 parts by weight of carboxy group-modified rubber composed of acrylic rubber was added, the electrical insulation was insufficient.

  The epoxy adhesive of the present invention can also be applied to coverlays, prepregs, metal-clad laminates, printed wiring boards, photosensitive resists, and photosensitive dry film resists.

It is a schematic sectional drawing which shows one Embodiment of the coverlay of this invention. It is a schematic sectional drawing which shows one Embodiment of the metal-clad laminated board of this invention. It is a schematic sectional drawing which shows one Embodiment of the printed wiring board of this invention. In the Example and comparative example of this invention, it is a top view which shows the copper circuit pattern for measuring the insulation resistance of printed wiring board (gamma).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Coverlay, 2 ... Insulating film, 3 ... Adhesive layer, 4 ... Metal-clad laminate, 5 ... Base film, 6 ... Adhesive layer, 7 ... Metal foil, 10 ... printed wiring board.

Claims (6)

  10 parts by mass or more and 50 parts by mass or less of a carboxy group-modified rubber is added to 100 parts by mass of a base resin containing a modified bisphenol A type epoxy resin having a flexible skeleton introduced through a low polar bonding group and a curing agent. An epoxy adhesive characterized by comprising:   The carboxy group-modified rubber is composed of carboxylated acrylonitrile butadiene rubber and carboxylated ethylene-acrylic rubber, and the compounding ratio of the carboxylated ethylene-acrylic rubber to the carboxylated acrylonitrile butadiene rubber is 20 to 80 (by mass ratio). The epoxy adhesive according to claim 1, wherein the epoxy adhesive is%. In the coverlay that is provided with an adhesive layer on one side of the insulating film,
10 parts of carboxy group-modified rubber is added to 100 parts by mass of a base resin containing a modified bisphenol A type epoxy resin having a flexible skeleton introduced through a low-polar bonding group and a curing agent. A cover lay characterized by being added in an amount of not less than 50 parts by mass. In a prepreg formed by impregnating an epoxy adhesive into a glass cloth,
10 parts by mass or more of carboxy group-modified rubber is added to 100 parts by mass of a base resin containing a modified bisphenol A type epoxy resin and a curing agent in which a flexible skeleton is introduced via a low-polar bonding group. A prepreg obtained by adding 50 parts by mass or less. In the metal-clad laminate in which an adhesive layer is provided between the base film and the metal foil,
10 parts of carboxy group-modified rubber is added to 100 parts by mass of a base resin containing a modified bisphenol A type epoxy resin having a flexible skeleton introduced through a low-polar bonding group and a curing agent. A metal-clad laminate obtained by adding not less than 50 parts by mass and not more than 50 parts by mass. A printed wiring board comprising the coverlay according to claim 3 attached to a metal foil surface of the metal-clad laminate according to claim 5.

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