JPH021789A - Epoxy resin adhesive and electrical circuit board - Google Patents

Abstract

PURPOSE:To obtain the subject adhesive having durable high heat-resistance, electrical insulation, moisture resistance and adhesivity stable over a long period and good workability by mixing specific epoxy resin, phenoxy resin (halide) and curing agent at specific ratios together with a solvent. CONSTITUTION:The objective adhesive is produced by kneading (A) an epoxy resin having an epoxy equivalent of >=800 and composed of bisphenol A and/or bisphenol F epoxy resin (or its halide), (B) a phenoxy resin (or its halide) having a number-average molecular weight of >=4,000 and a weight-average molecular weight of >=19,000 and (C) a curing agent produced by reacting an aromatic diamine and/or cycloaliphatic diamine with a polyfunctional epoxy resin having an epoxy equivalent of >=170 together with (D) a solvent. The weight ratio B/(A+B) in the adhesive is <50%.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to an epoxy resin adhesive used for bonding substrates and metal foils, coating agents, etc., and an electric circuit board using the epoxy resin adhesive. Regarding.

[Conventional technology]

With regard to electrical circuit boards such as printed wiring boards, metal printed wiring boards with high heat dissipation properties have recently been increasing as electronic devices become smaller, packaging density increases, and multilayer wiring becomes more common. This metal printed wiring board is made by bonding a metal foil such as copper foil or aluminum foil that serves as an electric path to a metal substrate such as aluminum, iron, brass, or copper using an insulating adhesive.

In this type of printed wiring board, as electronic devices become more multi-functional and diversified, adhesives with higher reliability are required. In other words, adhesives for printed wiring boards are heat resistant, electrically insulating,
There is a growing demand for good workability, such as excellent chemical properties such as moisture resistance and peel strength, fast curing speed during molding, and long self-life in the face state.

Epoxy resin adhesives conventionally used as adhesives for printed wiring boards include, for example, acrylonitrile-butadiene copolymer rubber (generally referred to as rNBRJ) and acrylonitrile-butadiene copolymer rubber (generally referred to as rNBRJ), which has a carboxyl group at the end of the molecule. rCTBNJ), polyester, soluble nylon, etc., to improve adhesion at room temperature.

[Problem to be solved by the invention]

Epoxy resin adhesives to which NBRXCTBN, polyester, or soluble nylon are added have improved adhesion at room temperature, but have problems in that high temperature adhesion, electrical insulation, and moisture resistance are significantly reduced.

In order to improve the heat resistance of epoxy resin adhesives, attempts have been made to add modified maleimide resins. However, epoxy resin adhesives containing modified maleimide resins have poor curability and moisture resistance, so there is a problem in that it is difficult to obtain sufficient reliability.

The first object of this invention is to overcome the above problems and provide an epoxy resin adhesive that has excellent heat resistance, electrical insulation, moisture resistance, and adhesive strength over a long period of time, and is also highly workable. do. Furthermore, a second object of the present invention is to provide an electric circuit board using an epoxy resin adhesive having such excellent properties.

[Means to solve the problem]

In order to solve the first problem mentioned above, the inventors conducted intensive research and found that a certain phenoxy resin was converted into NBR or C.
An epoxy resin composition that is used in place of TBN etc. to improve adhesion and uses a certain substance as a curing agent,
It was found that it has excellent chemical properties such as heat resistance, electrical insulation, moisture resistance, and peel strength. Moreover, this epoxy resin composition can be easily B-staged, has a long pot life at the B-stage, and has a fast curing speed during molding.
It has also been found that the self-life in the face state is long, and by adding a filler and/or a thixotropic material, the workability is good, such as good printability. In addition, an epoxy resin composition formed by kneading a filler and/or a thixotropic material using three specific epoxy compounds and a specific curing agent also has properties such as heat resistance, electrical insulation, moisture resistance, and peelability. It has excellent chemical properties such as strength, and
It has been found that by adding a curing accelerator, it is possible to cure in a short time and has good workability. When these epoxy resin compositions are used to form an adhesive layer on the surface of a substrate with a specific layer configuration, and a conductor circuit is formed on the adhesive layer, electrical It has also been found that a circuit board can be obtained. As a result, this invention was completed.

Therefore, in order to solve the first problem, the epoxy resin adhesive according to the invention of claim 1 has the following components (a
1, (b) and (c) are kneaded together with a solvent, and the weight of component bl is less than 50% of the total weight of components (11) and (bl).

In the epoxy resin adhesive according to the invention of claim 2, in the invention of claim 1, the following component d) is also kneaded together with the solvent.

(al At least one selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and their halides, with 80%
An epoxy resin having an epoxy equivalent weight of 0 or more.

(bl At least one of a phenoxy resin and its halide having a number average molecular weight of 4,000 or more and a weight average molecular weight of 119,000 or more.

(C) A curing agent obtained by reacting an aromatic diamine and/or a cycloaliphatic diamine with a polyfunctional epoxy resin having an epoxy equivalent of 170 or more.

(dl filler and/or thixotropic material.

In order to solve the first problem, the epoxy resin adhesive according to the invention of claim 3 contains the following components (Al, 031
．． (C), (DJ) and (2) are kneaded together.

(2) At least one selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and their halides, and 400%
An epoxy resin having an epoxy equivalent of or more than 10%.

(I3) At least one selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, glycidylamine type epoxy resin, and novola-ink type epoxy resin, and having an epoxy equivalent of less than 300. Epoxy resin.

(C) An epoxy resin dilution modifier that is at least one selected from the group consisting of glycidyl ether epoxy resins, glycidyl esters, and glycidyl amines and has a viscosity of 1000 cP or less at room temperature (25° C.).

■) A small amount selected from the group consisting of dicyandiamide, cycloaliphatic diamine and aromatic diamine.
Seed curing agent and curing accelerator (2) Filler and/or thixotropic material.

In order to solve the second problem, an electric circuit board according to the invention of claim 4 is provided, in which an adhesive HA made of the epoxy resin adhesive according to claim 1 or 2 is formed on the surface of the board. has been done.

In order to solve the second problem, the electric circuit board according to the invention of claim 5 has a first adhesive layer formed on the surface of the substrate, and a first adhesive layer formed on the surface of the first adhesive layer. In the electric circuit board in which two adhesive layers are formed, the first adhesive layer is adhesive layer B made of the epoxy resin adhesive according to claim 3, and/or the second adhesive layer is is the adhesive layer A made of the epoxy resin adhesive according to claim 1 or 2.

[For production]

The epoxy resin adhesive according to the invention of claim 1 or 2 (
In the component (hereinafter referred to as "adhesive A") (al~(d
The functions of l are as follows.Component (a) is the main ingredient of the adhesive and is a component that imparts adhesive properties.

The component (bl) has the function of improving the adhesive properties of the adhesive. Moreover, by using this component (b), NBR't') can improve the adhesive properties compared to adhesives using CTBN. It can be used as an adhesive with excellent high temperature adhesiveness and moisture resistance.

Component (C) is a curing agent for crosslinking component (a). By using component tc+ as a curing agent, B- can be achieved in a shorter time than with adhesives using conventional curing agents.
Can be staged and C-staged.

Component (d) is used in the epoxy resin adhesive according to the second aspect of the invention, and is added to improve printability, give the adhesive a desired thickness, and function as an insulating film.

In the epoxy resin adhesive according to the invention of claim 3 (hereinafter referred to as "adhesive B"), the functions of components (2) to 3 are as follows.

Component (A) is a main agent for imparting adhesive properties to the adhesive.

Component CB) has the function of improving the heat resistance of the adhesive.

Component (C) functions as a dilution modifier used to impart adhesion and liquefy component (A). As a result, the adhesive B can be made solvent-free or low-solvent, and can be applied thickly.

Component (D) is a curing agent for causing a crosslinking reaction between component (2), (Bl and (O), and a curing accelerator for promoting the crosslinking reaction.

By using these component colors) to (3), C-stage can be achieved in a shorter time than with conventional adhesives.

The component is added to give the adhesive a desired thickness and to function as an insulating film. By using this component (2), in the case of a system that contains a solvent during curing, the solvent bone can be quickly scattered.

In the electric circuit board according to the invention of claim 4, since the adhesive layer A with strong peel strength is formed on the surface of the board, the adhesive layer A with strong peel strength is stronger than that using a conventional adhesive. Provides good adhesion.

In the electric circuit board according to the invention of claim 5, at least one of an adhesive layer B made of adhesive B that can be applied thickly and an adhesive layer A having strong peel strength is formed on the substrate. Therefore, an adhesive layer of a desired thickness can be formed with fewer applications than conventional ones, and/or
Stronger adhesion with metal foil can be obtained.

〔Example〕

Components used in adhesive A (al is epoxy equivalent (hereinafter r)
EEWJ) is 800 or more epoxy resin, including bisphenol A epoxy resin, bisphenol F
One or more epoxy resins selected from the group consisting of type epoxy resins and their halides. The halide is, for example, a bromide. However, if the EEW of the epoxy resin of component (a) is less than 800, there is a problem that the peel strength at high temperatures decreases.

Note that the epoxy resin of component (a) has an EEW of 1500
It is preferable that it is above. This is because the peel strength at high temperatures is better.

Examples of bisphenol A type epoxy resins having the component (al) include those represented by the following formula 0 (n = a positive number of 4 or more).

As the bisphenol F type epoxy resin of component (a), there is, for example, one represented by the following formula 0 (n=positive number of 4 or more).

The epoxy resin of component (a) should be used alone or in combination of two or more, taking into consideration the solubility in solvents, blending ratio with hardening agent, peel strength at high temperatures, etc. .

Component (b) used in adhesive A has a number average molecular weight (r
At least one of a phenoxy resin and a halide thereof having a weight average molecular N (hereinafter referred to as rMWJ) of 19,000 or more and a weight average molecular N (hereinafter referred to as rMWJ) of 4,000 or more. The halide is, for example, a bromide. Phenoxy resin, for example, is synthesized from bisphenol A and shrimp chlorohydrin, but it is a high molecular weight polyhydroxy polyether that has almost no epoxy groups at the end, which is a characteristic of epoxy resin, and is a thermoplastic having the chemical structure shown below. It is resin.

, Mw is less than 19,000, the peel strength decreases,
In particular, there is a problem in that the peel strength at high temperatures decreases. ,
Some of the commercially available phenoxy resins preferred as component b) have M fl % M vi and dispersion (Mw
/Mn: standard of molecular weight distribution) are as shown in Table 1, but are not limited to these.

Table 1 Ingredients (bl is used to improve the adhesive properties of the adhesive. Component (bl) has a phenoxy resin and its halide with Mn of less than 4000, or component (c) used in adhesive A is is a curing agent obtained by addition-reacting a polyfunctional epoxy resin with an EEW of 170 or more to aromatic diamine and/or cycloaliphatic diamine. Examples of aromatic diamines include methylene bis(aniline), methylene bis( (toluidine), methylenebis(dimethylaniline), etc., each of which may be used alone or in combination of two or more, but is not limited to these. Examples of the cycloaliphatic diamine include, but are not limited to, isophorone diamine. Not done.EE
Examples of polyfunctional epoxy resins having a W of 170 or more include bisphenol A epoxy resins having an EEW of 180 to 500, bisphenol F epoxy resins having an EEW of 170 to 500, and xylenol having an EEW of 180 to 450 (for example, 2 .6-xylenol, etc.) dimer type epoxy resins, novolak type epoxy resins with an EEW of 170 to 220, and halogenated (e.g., brominated) bisphenol type epoxy resins with an EEW of 380 to 1300. Although more than one species can be used in combination, it is not limited to these. If a halogenated epoxy resin is used, it can be made nonflammable or flame retardant.

aromatic diamine and/or cycloaliphatic diamine,
A polyfunctional epoxy resin having an eff of 1170 or more is subjected to an addition reaction. This addition reaction is carried out by setting the combination of the two in consideration of the active hydrogen equivalent of the diamine and the EEW of the epoxy resin as an adduct agent. For example, it is preferable that 100 parts by weight of diamine be reacted with 20 to 600 parts by weight of epoxy resin. If the epoxy resin content is less than this ratio, there will be problems such as lower peel strength at high temperatures and increased toxicity of the curing agent; if it is more than this ratio, there will be problems with solubility in solvents and gelation. .

The above addition reaction is preferably carried out by heating at around 100° C. in a solvent, for example.

Performing under these conditions has the advantage of suppressing runaway reactions. Note that the above addition reaction may be performed under conditions other than these conditions.

In addition, although it is preferable to use only the above-mentioned component (C) as a curing agent in adhesive A, other curing agents may also be used in combination.

The blending ratio of component (a) and component (b) is 50% by weight of component b based on the total weight of component (a) and component (bl).
Must be less than This is because when the proportion of component (1)) exceeds 50% by weight, the peel strength at high temperatures decreases significantly. In addition, the ratio of component (bl is component + a
It is preferable that the amount is 5% by weight or more based on the total weight of component (b) and component (b). This is because if the ratio of component (b) is less than 5% by weight, the peel strength in normal conditions may decrease. Because there is.

Component (e) is basically used in a stoichiometric amount with respect to the epoxy group of component (a), but it may be used in excess or less than this, and the blending ratio is not particularly limited.

Adhesive A uses a filler and/or a thixotropic material as component (dl) and adhesive B as component (2).

The filler, for example, makes the adhesive a desired thickness,
It is added to function as an insulating film. It is preferable to use a filler with excellent electrical insulation and moisture resistance. For example, alumina, talc, silica, etc. are used alone or in combination of two or more.
Not limited to these. .

The thixotropic material prevents hard caking of the filler,
Used to improve workability such as fluidity and printability. Examples of the thixotropic material include, but are not limited to, colloidal silica, white carbon, asbestos, and the like, each used singly or in combination of two or more.

The amount of thixotropic material added varies depending on the type thereof, and is preferably determined based on workability and normal sedimentation state of the filler.

Adhesive A contains the above components (a), (bl, (cl)
In addition to (dl), accelerators and the like can be used alone or in combination of two or more, if necessary.

Adhesive A is obtained by uniformly dissolving and dispersing components (al, component (bl), component (c), component (dl), and other components added as necessary in a solvent, and kneading the mixture. The preparation method is not particularly limited.

In adhesive A, the solvent used to knead the ingredients is one that has a melting point equivalent to that of the epoxy resin of the ingredients (Al,
Alternatively, it is preferable to use a part or all of a solvent having a boiling point higher than the melting point by about 50°C. In this way, blistering of the coating film can be prevented when the adhesive is cured. In addition, when applying adhesive by printing method,
It is preferable to use a solvent having a vapor pressure of about 0.01 to 10 mmHg at 20°C.

Adhesive A is B-staged in approximately 3 to 30 minutes by heating at a temperature of 130 to 180°C.

The pot life at B-stage is approximately 30 to 120 days at a temperature of 5 to 30°C. This B-staged adhesive is then C-staged by heating at a temperature of 150 to 200°C for approximately 10 to 30 minutes.

Component (5) used in adhesive B is an epoxy resin having an EEW of 400 or more, and is one or more selected from the group consisting of bisphenol A epoxy resin, bisphenol F epoxy resin, and their halides. It is an epoxy resin. The halide is, for example, a bromide.

If the EEW of the epoxy resin of component (2) is less than 400, there is a problem that the peel strength at high temperatures decreases.

As the bisphenol A type epoxy resin of component (A), for example, in the above formula 0, n is represented by a positive number of 1 or more.

The bisphenol F type epoxy resin of component (A) is, for example, one represented by n=1 or more positive number in the above formula 0.

The epoxy resin of component (2) can be used alone or in combination of two or more, taking into consideration the viscosity after liquefaction, the blending ratio with the curing agent, the peel strength at high temperatures, the curing speed, etc. use.

Component 031 used in adhesive B is an epoxy resin with an EEW of less than 300, selected from the group consisting of bisphenol A epoxy resin, bisphenol F epoxy resin, glycidylamine epoxy resin, and novolak epoxy resin. One or more selected epoxy resins. If the EEW of the epoxy resin of component (Bl) is 300 or more, the viscosity of the adhesive after kneading will increase, resulting in poor workability, or a larger amount of component (a) will be added, resulting in peeling at high temperatures. There is a problem that the strength decreases.

Commercially available products that can be used as component (B) include, for example, Epicoat 8 (trademark) manufactured by Yuka Shell Epoxy Co., Ltd.
28 (bisphenol A type epoxy resin), trademark Epicote 807 (bisphenol F type epoxy resin) manufactured by Yuka Shell Epoxy Co., Ltd., trademark TETRAD (glycidylamine type epoxy resin) manufactured by Mitsubishi Gas Chemical Co., Ltd., Yuka Shell Epoxy Co., Ltd. trademark epiny) made by the company
154 (novolac type epoxy resin), etc., respectively.

Components used in adhesive B (a is at least one member selected from the group consisting of glycidyl ether-based epoxy resins, glycidyl esters, and glycidyl amines,
It is an epoxy resin dilution modifier that has a viscosity of 1000 cP or less at room temperature (25°C). If the viscosity of component (C) at room temperature exceeds 1000 cP, there is a problem that workability such as printability deteriorates.

Commercially available products that can be used as component (C) include, for example, Nitto Kasei Co., Ltd.'s trademark Eboniso) 028 (aliphatic polyglycidyl ether epoxy resin), Yuka Shell Epoxy Co., Ltd.'s trademark Cardura E10 (carboxylic acid). monoglycidyl ester), trademark GOT, GAN (aminoglycidyl ether) manufactured by Nippon Kayaku Co., Ltd.
etc. can be mentioned respectively.

Component CB) and component (C), like component (2), can be used alone or in combination of two or more, taking into consideration the viscosity of the adhesive after liquefaction, peel strength, etc. do.

Component D) used in adhesive B includes at least one curing agent (hereinafter referred to as "specific curing agent") selected from the group consisting of dicyandiamide, cycloaliphatic diamine, and aromatic diamine, and , a curing accelerator. Examples of the aromatic diamine and cycloaliphatic diamine used here include those mentioned above. The curing accelerator used here includes benzyldimethylamine, imidazoles, salicylic acid, DBU (1,8-diazabicyclo(
5,4,0) undecene-7] and the like, each of which may be used alone or in combination of two or more, but is not limited thereto.

In adhesive B, it is preferable to liquefy component () before use. This is due to the dispersibility of the component (component ■) and the base agent (components (A) to (C)) by liquefying DJ.
This is because it can improve solubility, uniformly harden, and improve adhesion.

A solvent may be used to liquefy the component (DJ), and examples of the solvent include DMF (N,N-dimethylformamide) and methyl cellosolve, each of which may be used alone or in combination of two or more. However, the proportions of the specific curing agent, curing accelerator, and solvent are not particularly limited when liquefying the components (), but the proportions of the specific curing agent, curing accelerator, and solvent are not particularly limited. It is preferable to use 5 to 15 parts by weight of the agent and 0 to 1000 parts by weight of the solvent. If the ratio of the curing accelerator is out of this range, the curing properties may deteriorate or the cured product may become brittle. If the ratio of the solvent exceeds 1000 parts by weight, the solvent may remain or the cured film may become brittle. There is a risk that the thickness may become thinner.

In addition, although it is preferable to use only the specific curing agent of the component Dl as a curing agent in the adhesive B, other crosslinking agents may be used in combination.

The blending ratio of component (A), component (B) and component (0) is
Although not particularly limited, it is preferable that these three components (2) to (component color) be 30 parts by weight or more based on 100 parts of the total weight of a. This is because if the proportion of component (5) is less than 30 parts by weight, the peel strength under normal conditions may become low. Component Q3) is preferably contained in an amount of 5 to 50 parts by weight, more preferably 10 to 40 parts by weight, based on 100 parts of the total weight. If the amount of component (g)) exceeds these ranges, the adhesiveness may decrease, and if the amount exceeds these ranges, the heat resistance may decrease.

Component (a is a low-viscosity reactive resin used to impart adhesion and dissolve component (A+); component (5)
The proportion is preferably 100 parts by weight or less, more preferably 80 parts by weight or less, based on 100 parts by weight. If the proportion of component (a) exceeds these ranges, the peel strength at high temperatures may decrease significantly.

Components) are basically components (2), (B) and (C
) is used in a theoretical amount in terms of stoichiometric equivalent of the epoxy equivalent, but it may be used in excess or less than the theoretical amount, and the blending ratio is not particularly limited. For example, when dicyandiamide (DICY) is used, it is used in a proportion of about 1/2 of that of 34 il.

Adhesive B contains the above components (2), (B), (C),
■) and other ingredients other than (2), if necessary, 1
It can contain more than one species.

Adhesive B is obtained by uniformly kneading component (A), component (B), component (C), component CD+, component surface, and other components added as necessary.
The preparation method is not particularly limited.

In adhesive B, if a solvent is used to knead the ingredients, the solvent must have a melting point equal to or 50% higher than the melting point of the epoxy resin of component (A).
It is preferable to use some or all of the solvents having a boiling point as high as 0.degree. In this way, it is possible to prevent the adhesive coating from blistering during curing.

Adhesive B is C-staged in approximately 3 to 30 minutes by heating at a temperature of 130 to 180°C.

Adhesive A and adhesive B are each used, for example, to bond a substrate and a metal foil. When making an electrical circuit board using Adhesives A and B, apply Adhesive A and/or Adhesive B to the substrate and/or metal foil in a desired manner, and after splattering the solvent or B-stage. , the substrate and the metal foil are bonded together via an adhesive and completely cured (C staged). The adhesive layer provided between the substrate and the metal foil may be one layer or two or more layers.

When providing two or more adhesive layers, on the side that contacts the substrate,
An adhesive layer made of adhesive A (hereinafter referred to as "adhesive layer A") may be provided, or an adhesive Fi made of adhesive B (hereinafter referred to as "adhesive layer B") may be provided. Adhesive A
, B may be provided. Further, the adhesive layer A may be provided on the side in contact with the metal foil, or a layer made of an adhesive other than adhesives A and B may be provided. However, if the electrical insulation in the thickness direction of the electrical circuit board is to be ensured by the thickness of the adhesive layer, as will be described later, adhesive layer B is provided on the side in contact with the board, and adhesive layer B is provided on the side in contact with the metal foil. Preferably, a coating layer A is provided. In this way, it is easy to form a thick layer of adhesive B, so the application work of adhesive A and the application work of adhesive B can be performed as few times as one time each, and electrical insulation in the thickness direction can be easily achieved. In addition, since adhesive A has excellent peel strength, especially at high temperatures, it can also ensure good adhesion to metal foil. When providing adhesive layer B on the substrate side, after applying adhesive B to the substrate and forming a C-stage, adhesive A is applied to adhesive NB and metal foil is bonded together, or adhesive A is applied to the substrate to form a C-stage. Adhesive A can also be made into a C-stage by bonding coated metal foils together. In this way, the adhesive B of the present invention may be used in such a manner that it is completely cured in advance and then bonded with another adhesive layer.

As the substrate, for example, one for an electric circuit board is used, and metal materials such as aluminum, brass, copper, and iron, or organic materials such as glass epoxy resin and phenol resin are used. As the metal foil, for example, electrolytic copper foil, rolled copper foil, aluminum foil, etc. are mainly used.

Adhesive A and Adhesive B are used to apply a desired circuit pattern to a board using printing methods, etc., and then apply metal plating or apply conductive paste on top of it to form electrical circuits. can. The uses of adhesives A and B are:
Not limited to these materials, for example, it can be used as a deep coating agent, a partial insulating agent for the purpose of protecting hybrid ICs, etc. for printed wiring boards by taking advantage of its characteristics such as good electrical insulation and adhesive properties. It is used for coating of hybrid ICs, coating of hybrid ICs, etc.
It can also be used as a botting agent for electronic parts. In particular, since adhesive B can be applied thickly as described above, when used as a coating agent, etc., it also has the advantage that the number of application operations can be reduced.

In this invention, the term "electric circuit board" refers not only to a board on which an electric circuit is formed on the surface of the board, but also to a board with metal foil pasted on the board, or a board with an electric circuit formed on the surface of the board. It also includes those in which an electric circuit is formed with an insulating layer sandwiched between the circuits (multilayer circuit board), and those in which circuit elements are mounted and connected after the electric circuit is formed on the surface of the board.

The electric circuit board according to the invention of claim 4 has an adhesive layer A formed of the adhesive A according to the invention of claim 1 or 2 on the substrate. On this adhesive layer A, for example, metal foil, metal plating film, conductive paste Fi, etc. are bonded.

This electric circuit board can be produced, for example, by applying adhesive A to a substrate and/or metal foil in a desired manner, and after splattering with a solvent or B-staged, the substrate and metal foil are bonded together via adhesive layer A. It is obtained by superimposing them and completely curing them (C-staged).

FIG. 1 shows one embodiment of an electric circuit board according to the invention. This electric circuit board 100 is made of gold Hr on the surface of a metal plate 1, which is a substrate for an electric circuit board, through an adhesive layer A.
7r32 is joined.

The electric circuit board according to the invention of claim 5 has a first
An adhesive layer is formed, and a second adhesive layer is formed thereon, and the first adhesive layer is formed of adhesive B and/or the second adhesive layer is formed of adhesive A. It is characterized by being formed of. On this adhesive layer A, for example, a metal foil, a metal plating film, a conductive paste layer, etc. are bonded.

FIG. 2 shows a first embodiment of the electric circuit board according to the fifth aspect of the invention. In this electric circuit board 10, an adhesive layer B, which is a first adhesive layer, is formed on a metal plate 1, which is a substrate for an electric circuit board, and a second adhesive layer is formed on the first adhesive layer. An adhesive layer A, which is a layer, is formed, and a metal plate l and a metal T
32 are bonded together with adhesive layers A and B sandwiched therebetween.

The first adhesive layer is formed mainly for the purpose of insulation when an insulation distance is required due to voltage resistance or the like. Adhesive B can be applied thickly, for example, in thick film printing.
When forming the first adhesive layer with
A desired thickness can be obtained with one coating, the number of coating steps can be reduced, and costs can be reduced. Furthermore, since the adhesive B has a short curing time, it also saves energy. Note that the first adhesive layer may be formed using an adhesive other than adhesives A and B. The second adhesive layer is mainly intended for adhesion, and is formed from, for example, adhesive A that has strong peel strength at room temperature and high temperature. Adhesive A also has the advantage of being easily B-staged and easy to work with for joining metal foils and the like. The second adhesive layer may be formed using an adhesive that cannot be applied thickly as long as it has good adhesive properties, and does not need to be formed from adhesive A.

In this way, adhesive layer B and adhesive layer A are formed on the surface of the substrate.
By combining the two, it is possible to compensate for the weaknesses of each and effectively utilize the strengths of each. When adhesive B is used in the first adhesive layer, the effect of adhesive B is exhibited, and when adhesive A is used in the second adhesive layer, the effect of adhesive A is exhibited. . When adhesive B is used for the first adhesive layer and adhesive A is used for the second adhesive layer, the effects of both adhesives A and B are exhibited.

In particular, when the electric circuit board is a multilayer printed wiring board, the adhesive layer B is most excellent as an insulating layer after the second insulating layer. The second conductor layer formed on the adhesive layer may be formed of a metal paste such as a copper paste, or may be formed by plating using an additive method.

In the invention of claim 5, in the adhesive structure consisting of two layers, the first adhesive layer and the second adhesive layer, it does not matter which one of the adhesives iA and B is the main adhesive. In other words, as shown in the second embodiment of FIG. The adhesive layer A may be formed by applying a thin layer of adhesive A only to the portion 3, or as shown in the electric circuit board (metal printed wiring board) 12 of the third embodiment shown in FIG. The adhesive layer A may be formed by applying a thin layer of adhesive A to the entire surface of one side of a certain metal plate 1. 2nd~
In Figure 4, the same numbers and symbols are given to the same parts.

Adhesive A in advance on the metal foil to form adhesive NA
may be applied, B-staged if necessary, and then bonded with adhesive NB. For example, when a withstand voltage of 5 kV is required, the thickness of the adhesive layer B is approximately 1 On, and the thickness of the adhesive layer A is approximately 10 nm, but the present invention is not limited thereto.

Adhesive A will be mainly considered. When forming an electric circuit by sandwiching an insulating layer on the surface of a metal plate that is a substrate, or by sandwiching an insulating layer (second insulating layer) on the electric circuit (first conductive circuit layer) formed on the surface of the substrate. Furthermore, when forming an electric circuit (second conductive circuit layer), insulation reliability is not very high if the thickness of the insulating layer is thin. For example, as shown in FIG. 8, if an insulating layer is formed only with adhesive A, which does not form a thick film in one application, the edge portions of the first conductor circuit layer 5 formed on the surface of the substrate 4 ( The thickness of the adhesive layer A at the upper end) is too thin, resulting in low insulation reliability.

Therefore, instead of forming an insulating layer only with adhesive A,
First, adhesive B, which can be applied thickly, is applied to form adhesive layer B, and then adhesive A is applied on top of adhesive layer B to form adhesive layer A, which serves as an insulating layer. It improves sex. For example, as shown in Figures 2 to 7. 2 to 4 have already been explained. Note that the same numbers and symbols are given to the same parts in FIGS. 1 to 8.

FIG. 5 shows a fourth embodiment of the electric circuit board according to the fifth aspect of the invention. This electric circuit board 13 has an insulating layer (second insulating layer) on the first conductor circuit layer 5 formed on the surface of the substrate 4.
A second conductor circuit layer 6 is further formed on both sides, and as the insulating layer, an adhesive layer A is formed on the second conductor circuit layer 6 side, and an adhesive layer B is formed on the substrate 4 side. ing.

FIG. 6 shows a fifth embodiment of the electric circuit board according to the fifth aspect of the invention. This electric circuit board 14 has an adhesive layer B formed by applying an adhesive B between the first conductor circuits N5 formed on the surface of the board 4, and the first conductor circuit layer 5 and the adhesive layer A second conductive circuit layer 6 is further formed on top of B with an adhesive layer A, which is an insulating layer, interposed therebetween. In this way, the difference in level between the recesses between the first conductive circuit layers 5 is reduced, or the adhesive layer B is made higher than the first conductive circuit layer 5, so that the thickness of the insulating layer is increased. The insulation reliability at the edge portion E of the first conductive circuit layer 5 can be improved without deteriorating along the edge portion. The adhesive layer B between the first conductive circuit layers 5 may cover the edge portion E side portion of the first conductive circuit layer 5, as shown in FIGS. 7(al) and 7(b). Alternatively, the adhesive layer B and the adhesive layer A may be formed between the first and second conductive circuit layers 5 and 6 in a configuration as shown in FIG.

In the first to sixth embodiments above, for example, withstand voltage 2k
When V is required, the thickness of the adhesive layer B is approximately 3 On, and the thickness of the adhesive layer A is approximately 30 mm, but is not limited thereto.

Note that this invention is not limited to what has been described above. For example, when the electric circuit board according to each of claims 4 and 5 is a multilayer circuit board, the board and the first conductive circuit layer formed on the surface of the board are bonded using only adhesive A. Alternatively, it may be performed by forming adhesive layer B on the substrate side and adhesive layer A on the first conductive circuit layer side, or by using adhesives other than adhesives A and B. You may also use

Specific examples and comparative examples of this invention are shown below, but the invention is not limited to the following examples. A fitted 500 d 4 day flask was used. This flask was charged with diamine and butyl cellosolve shown in Table 2 at a ratio of diamine:butyl cellosolve = 2:1 (weight ratio) as shown in Table 2, sealed with nitrogen, and heated to dissolve at 70°C. On the other hand, the polyfunctional epoxy resin shown in Table 2 was dissolved in butyl cellosolve at the ratio shown in Table 2, and this solution was dropped into a flask over 1 hour on 4 days to react the diamine and the epoxy resin. Although this reaction was exothermic, the temperature was controlled so as not to exceed 120°C. After the exothermic reaction was completed, the reaction mixture was heated to 130° C. and stirred for 1 hour to complete the reaction, and each of component (C) (symbols ① to ①) was obtained in a state dissolved in butyl cellosolve. Component (C) I to
No. 18 and Comparative Example 1 were used.

- Examples 1 to 18 - Epoxy resins A-E shown in Table 3 were used as components (al). Phenoxy resin A shown in Table 3 was used as component (b).
-D was used.

Component (a) was heated and dissolved in the same xylene [1]. This solution is called liquid (2).

Component (a) is mixed with the same weight of methyl ethyl ketone (rM
(denoted as EKJ). This solution is called liquid (2).

Component (b) was mixed and dissolved in a xylene/MEK mixed solvent (weight ratio xylene:MEK=I:1) to a concentration of 35% by weight. This solution was mixed with 60% by weight of molten alumina (average particle size 1 to 5 μm layer) to the solution (referred to as solution (2)), and then passed through three rolls to fully disperse the alumina. This dispersion liquid is called liquid (2).

4 thixotropic material made of colloidal silica against xylene
The colloidal silica was added at a ratio of 0% by weight and kneaded to sufficiently disperse the colloidal silica. This dispersion liquid is called liquid (2).

Each solution of component (C) is referred to as solution (2).

The liquid ■
~■, Xylene and MEK were appropriately combined and kneaded with a disperser to obtain an epoxy resin adhesive. Note that in Examples 13 to 18, filler and thixotropic material were not used, and a clear type adhesive was used. An epoxy resin adhesive was obtained in the same manner as in the example.

Comparative Example 3 - An epoxy resin adhesive was obtained in the same manner as Comparative Example 2, except that CTBN was used instead of NBR.

In addition, in all Examples 1 to 18, the curing agent component (
This means that about twice the theoretical amount of c) was added. Moreover, each comparative example was also the same.

- Comparative Example 1 - Epoxy resin adhesives were obtained in the same manner as in the examples using the compounds shown in Tables 2 and 3 in the proportions shown in each table.

Comparative Example 2 - NBR was used instead of component (b), DDS (diaminodiphenylsulfone) was used instead of component (C), MIBK was used instead of xylene and butyl cellosolve.
Using each of the epoxy resin adhesives of Examples and Comparative Examples using (methyl isobutyl ketone), the physical properties were investigated in the following manner, and the results are shown in Table 4. In addition, as shown in Table 4, the adhesive of Example 1 is 1-1. 1
-2. It was cured under three conditions of L-3.

An aluminum slope (thickness in) was used as the substrate, and an electrolytic copper foil (thickness 35 μmA) was used as the metal foil. Each epoxy resin adhesive was applied to one side of the substrate, placed in a hot air circulation constant temperature bath, and brought to a B-stage (semi-cured state) at the temperature and time shown in Table 4. The thickness of the adhesive at this time was 100 μl. After that, metal foil was placed on top of the adhesive and heat pressed (pressure 10 kgf/cnl).
The adhesive was brought to a C-stage (completely cured state! 3) by the following steps, and an electric circuit board was obtained. Heat press time and temperature are 4th
It was as shown in the table.

For each electrical circuit board, the peel strength at normal temperature, the peel strength at 150° C., the solder heat resistance, the surface resistance, the volume resistance, and the surface resistance after the electrical corrosion test were examined as follows.

Room temperature peel strength, soldering heat resistance, surface resistance, volume resistance, and surface resistance after electrical corrosion test are in accordance with JIS standard C648-1.
(Test method for copper-clad laminates for printed wiring boards).

The 150°C peel strength was measured by a test method according to the above-mentioned JTS standard after being immersed in oil at 150°C for 5 minutes.

The electrical corrosion test was conducted by applying a DC voltage of 100 μm and leaving the sample at a temperature of 60° C. and a humidity of 95% for 500 hours.

As shown in Table 4, each of the adhesives of the Examples was able to be B-staged and C-staged in a shorter time than that of the Comparative Example. Furthermore, each of the adhesives of Examples had a 1.50°C peel strength greater than that of Comparative Example 2, and had a good surface resistance after the electrical corrosion test. Furthermore, each of the adhesives of Examples was superior to that of Comparative Example 3 in all physical properties.

Example 19 - Components (5) and (0) in the amounts shown in Table 5 are heated and melted at 80°C to dissolve each other, and further, component (I3) in the amount shown in Table 5 is added and mixed. A uniform liquid resin was obtained. This liquid resin is referred to as liquid (2).

The amounts of components shown in Table 5 (Dl were mixed with DMF-butyl cellosolve mixed solvent (weight ratio DMF nibutyl cellosolve = 1:
5) and stirred at room temperature for 1 hour to dissolve. This solution is called liquid (2).

Component (2) was added to liquid (2) in the amount shown in Table 5 and kneaded, and then passed through three rolls to fully disperse component (2). This dispersion liquid is called liquid (2).

Adhesive B was obtained by kneading Liquid (2) and Liquid (2) using a dispersion machine in the proportions shown in Table 5.

This adhesive B was applied to one side of an aluminum plate (substrate) having a thickness of 11 m, and was cured by heating at 180° C. for 10 minutes to form a C-stage. The thickness of the adhesive layer B at this time is approximately 60 mm.
It was μ heavy. Adhesive A of Example 2 was applied onto adhesive layer B and cured by heating at 160° C. for 10 minutes to form a B-stage. The thickness of the entire adhesive layer at this time (adhesive layer A
The thickness of adhesive layer B) was approximately 90 μl.

An electrolytic copper foil having a thickness of 35 μl was superimposed on the adhesive layer A, and the adhesive A was made into a C-stage by hot pressing to obtain an electric circuit board. Heat press conditions are pressure 10kgf/c
al, temperature was 180° C., and time was 15 minutes.

Examples 20-25 Adhesive B was made in the same manner as in Example 19 using the ingredients shown in Table 5. Then, each adhesive B was used to obtain an electric circuit board in the same manner as in Example 19.

Example 26 - Adhesive B was made in a manner similar to Example 19 using the ingredients listed in Table 5. Then, as adhesive A, Example 1
An electric circuit board was obtained using adhesive B in the same manner as in Example 19, except that adhesive No. 3 was used.

Comparative Example 4 In place of components (5) to (C) in Example 19, the same amount of epoxy resin (trademark Epicoat 828 manufactured by Yuka Shell Epoxy Co., Ltd.: EEW = 190) was used in Example 1.
An epoxy resin adhesive was obtained in the same manner as in Example 9. Then, using this epoxy resin adhesive, an electric circuit board was obtained in the same manner as in Example 19. Comparative Example 5 - Same as in Example 19 except that CTBN was used instead of component (A). An epoxy resin adhesive was obtained. Then, using this epoxy resin adhesive, an electric circuit board was obtained in the same manner as in Example 19.

Examples 27-33 Adhesive B was made in the same manner as in Example 19 using the ingredients shown in Table 5. Then, each adhesive B was used in the same manner as in Example 19, except that adhesive A was not applied and the metal foils were not overlapped and heat pressed. I got the circuit board.

Comparative Example 6.7 - An electric circuit board without metal foil was obtained in the same manner as in Example 27, except that each epoxy resin adhesive of Comparative Example 4.5 was used instead of adhesive B.

Example 34 The metal foil of the electric circuit board obtained in Example 3 was removed by etching in a desired circuit pattern to form a first conductive circuit layer. Adhesive B of Example 27 was applied onto this first conductor circuit layer.
was partially applied by screen printing, and the adhesive B was made into a C stage in the same manner as in Example 27. Adhesive A of Example 13 was applied onto the JiH adhesive by screen printing to B-stage the adhesive A in the same manner as in Example 13. The thickness of the insulating layer at this time was 60 μl for adhesive layer B and 10 μl for adhesive layer A. A second conductive circuit layer is formed on the adhesive layer A using a semi-additive method using 35 μm of copper in a desired circuit pattern, and the adhesive A is made into a C stage in the same manner as in Example 13, so that the side cross section is An electric circuit board having a multilayer circuit structure as shown in FIG. 5 was obtained.

Example 35 In Example 34, the adhesive B of Example 27 was applied between the first conductor circuit layers by screen printing, and the first
A multilayer circuit structure having a side cross section as shown in FIG. 6 was prepared in the same manner as in Example 34, except that the adhesive A of Example 2 was used as the adhesive A applied on the conductive circuit layer and the adhesive layer B. An electrical circuit board was obtained. The thickness of adhesive layer B at this time is 50n,
The thickness of 1 mA of adhesive was 20 μm.

Each of the electrical circuit boards of Examples 19 to 26, 34, and 35 and Comparative Example 45 was examined for room temperature peel strength, solder heat resistance, surface resistance, volume resistance, and 150°C peel strength by the above-mentioned methods. The results are shown in Table 6.

The volume resistivity, surface resistance, and solder heat resistance of each of the electric circuit boards of Examples 27 to 33 and Comparative Example 6.7 were examined, and a board grain test was conducted. The foundation test is based on JIS standard 5.
400. The results are shown in Table 6.

As shown in Table 6, the electrical circuit boards of Examples 19 to 26.3435 have higher peel strength at high temperatures (and better soldering heat resistance) than those of Comparative Examples 4 and 5. The electric circuit board of No. 33 has better board grain test results and better soldering heat resistance than that of Comparative Example 6.7.
In the electric circuit board No. 5, the insulation reliability between the first conductive circuit layer and the second conductive circuit layer was also good.

〔Effect of the invention〕

As described above, the epoxy resin adhesive according to the invention of claim 1 is made by kneading components (a) to (c) with a solvent, and therefore has excellent heat resistance, electrical insulation, moisture resistance, and adhesive strength. There is. Moreover, such excellent performance is obtained without adding rubber or the like. In addition, it is easy to B-stage, has a long pot life at the B-stage, has a fast curing speed during molding, and has a long self-life in the face state, so it has good workability.

The epoxy resin adhesive according to the invention of claim 2 is the epoxy resin adhesive according to the invention of claim 1, which contains the component (
Since d+ is also kneaded, in addition to that, it has electrical insulation properties,
Workability such as printability is better.

As described above, the epoxy 4M fat adhesive according to the invention of claim 3 has excellent heat resistance, electrical insulation, moisture resistance, printability, and adhesive strength because the component A1 and the feathers are kneaded together. There is. Moreover, since it can be applied thickly,
Less coating work is required to form a film of desired thickness. In addition, the curing speed during molding is fast and workability is good.

Since the electrical circuit board according to the invention of claim 4 has the adhesive layer A as described above, it has an adhesive layer with excellent adhesive properties.

Since the electric circuit board according to the invention of claim 5 has the adhesive layer A and/or the adhesive layer B as described above, the adhesive layer has excellent adhesive properties and/or has a It is designed to form an adhesive layer that can easily be thickened.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a portion of one embodiment of an electric circuit board according to the invention of claim 4, and FIG. 2 is a sectional view of a portion of the first embodiment of the electric circuit board according to the invention of claim 5. 3 is a sectional view of a part of the second embodiment, FIG. 4 is a sectional view of two parts of the third embodiment, and FIG. 5 is a sectional view of a part of the fourth embodiment. 6 is a cross-sectional view of a portion of the fifth embodiment, FIG. 7 (al is a cross-sectional view of a portion of the sixth embodiment, and FIG. 7 is a point on the right side of FIG. 7(a). FIG. 8 is an enlarged view of the part surrounded by a chain line circle and a cross-sectional view of a part of another embodiment of the electric circuit board according to the invention of claim 4. 1.4... Substrate 2, 3. ...Metal foil 5...1st
Conductor circuit layer 6...Second conductor circuit layer 10, 11, 1
213.14,15,100...Electric circuit board A...
・Adhesive layer AB...Adhesive layer BE...First conductor circuit shoulder Edge Department Agent Patent attorney Takehiko Matsumoto 1st Figure 3

Claims (1)

[Scope of Claims] 1. The following components (a), (b) and (c) are kneaded together with a solvent, and the weight of component (b) is relative to the total weight of components (a) and (b). Epoxy resin adhesive that is less than 50%. (a) An epoxy resin that is at least one selected from the group consisting of bisphenol A epoxy resins, bisphenol F epoxy resins, and halides thereof, and has an epoxy equivalent of 800 or more. (b) Number average molecular weight 4000 or more and weight average molecular weight 1
At least one of a phenoxy resin and a halide thereof having a molecular weight of 9,000 or more. (c) A curing agent obtained by reacting an aromatic diamine and/or a cycloaliphatic diamine with a polyfunctional epoxy resin having an epoxy equivalent of 170 or more. 2. The epoxy resin adhesive according to claim 1, wherein the following component (d) is also kneaded together with a solvent. (d) Fillers and/or thixotropic materials. 3 The following components (A), (B), (C), (D) and (
An epoxy resin adhesive obtained by kneading E) together with E). (A) An epoxy resin that is at least one selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and halides thereof, and has an epoxy equivalent of 400 or more. (B) At least one epoxy resin selected from the group consisting of bisphenol A epoxy resin, bisphenol F epoxy resin, glycidylamine epoxy resin, and novolac epoxy resin, and having an epoxy equivalent of less than 300. . (C) An epoxy resin dilution modifier that is at least one member selected from the group consisting of glycidyl ether epoxy resins, glycidyl esters, and glycidyl amines and has a viscosity of 1000 cP or less at room temperature (25° C.). (D) At least one selected from the group consisting of dicyandiamide, cycloaliphatic diamine, and aromatic diamine
Seed curing agent and curing accelerator (E) Filler and/or thixotropic material. 4. An electric circuit board having an adhesive layer A made of the epoxy resin adhesive according to claim 1 or 2 formed on the surface of the substrate. 5. In an electric circuit board in which a first adhesive layer is formed on the surface of the substrate and a second adhesive layer is formed on the surface of the first adhesive layer, the first adhesive layer is The adhesive layer B is made of the epoxy resin adhesive according to Item 3;
and/or the second adhesive layer is
An electric circuit board characterized in that the adhesive layer A is made of the epoxy resin adhesive described above.