JP2001302887A - Epoxy resin composition, metal foil with resin, and insulating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition scarcely causing cracking or peeling, etc., in a semicured state (B stage) and without making a resin residue remain in a cured state even when via holes are formed by carrying out perforation with laser beams. SOLUTION: This epoxy resin composition consists essentially of a novolak type epoxy resin and a cross-linked rubber having <=1 μm particle diameter. The amount of the novolak type epoxy resin contained therein is 20-80 pts.mass based on 100 pts.mass of the solid content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an epoxy resin composition, a metal foil with resin, and an insulating film used for manufacturing a printed wiring board and the like.

[0002]

2. Description of the Related Art In recent years, in the production of multilayer printed wiring boards,
Metal foils with resin and insulating films are widely used, and these are produced and used as follows.

A resin-coated metal foil is formed by applying a resin such as an epoxy resin composition to one surface of a metal foil such as a copper foil and semi-curing the resin to form a semi-cured resin layer on the metal foil surface. It is produced. Then, a semi-cured resin layer of the resin-coated metal foil is superimposed on one or both sides of the inner layer substrate on which a circuit pattern has been formed as an inner layer circuit, and heated and pressed to form a semi-cured resin. The resin is completely cured to form a cured resin, and a multilayer wiring board can be manufactured. Thereafter, a laser hole is formed in the multilayer wiring board to form a via hole, and a subtractive method or the like is performed on the outer metal foil to form a circuit pattern as an outer layer circuit, thereby forming a circuit pattern between the inner layer circuit and the outer layer circuit. It is possible to manufacture a multilayer printed wiring board in which conduction has been achieved.

On the other hand, an insulating film is formed by applying a resin such as an epoxy resin composition to the surface of a carrier film such as a PET film and semi-curing the resin to form a film-like semi-cured resin on the carrier film. Produced. Then, the surface of the semi-cured resin formed in the form of a film of the insulating film is superimposed on one or both surfaces of the inner layer substrate similar to the above, and this is heated and pressed to form a laminate, thereby forming the semi-cured resin. Is completely cured to obtain a cured resin, whereby a multilayer wiring board can be manufactured. Thereafter, the carrier film covering the outside of the multilayer wiring board is peeled off, and the exposed cured resin is drilled with a laser to form a via hole, and by performing an additive method or the like on the surface of the cured resin, A circuit pattern is formed as an outer layer circuit, and a multilayer printed wiring board in which conduction between the inner layer circuit and the outer layer circuit is established can be manufactured.

[0005] However, the above-mentioned semi-cured resin such as resin-coated metal foil and insulating film is generally fragile, and when subjected to an impact during handling before lamination molding,
In some cases, the semi-cured resin was cracked or peeled off to generate resin pieces or resin powder. The multilayer printed wiring board manufactured using the resin-coated metal foil or the like in which the semi-cured resin is damaged as described above has a problem that the damaged portion of the semi-cured resin becomes a cavity and the insulation between the inner layer circuit and the outer layer circuit is reduced. There is a problem that the property is reduced.

Further, if resin powder or the like generated before adheres to the surface of the metal foil of the resin-attached metal foil before lamination molding, fine hardening occurs on the surface of the metal foil of the multilayer wiring board to be manufactured. A resin is formed. When a circuit pattern is formed by performing etching or the like on the metal foil of such a multilayer wiring board, a portion where the cured resin is formed remains without being removed, and if this portion is a portion that should be originally removed, Short circuit failure occurs between circuit patterns in a manufactured multilayer printed wiring board, and the yield is reduced.

[0007] Therefore, by adding a non-crosslinked rubber or a phenoxy resin as a component for imparting plasticity to an epoxy resin composition or the like that forms a semi-cured resin such as a metal foil with a resin, the semi-cured resin has flexibility. To avoid damages such as cracks and peeling.

[0008]

However, in the case of a metal foil with a resin in which a non-crosslinked rubber is blended with a semi-cured resin, cracks and peeling of the semi-cured resin are less likely to occur. Such semi-cured state (B-stage)
Tacking on (the property of sticking in a short time with a light force)
Therefore, there is a problem that semi-cured resins such as metal foils with different resins or the semi-cured resin and the metal foil are inadvertently adhered to each other during handling before lamination molding.

On the other hand, in the case of a semi-cured resin in which a phenoxy resin is blended, the semi-cured resin is hardly cracked or peeled off. Resin residues are easily generated by laser processing, and when a via hole is formed by drilling with a laser, there is also a problem that poor conduction occurs due to the resin residues generated inside the holes after laser processing.

The present invention has been made in view of the above points. In a semi-cured state (B-stage), cracks and peeling are less likely to occur, and no tacking is exhibited. In the state, an object is to provide an epoxy resin composition in which a resin residue does not remain even when a via hole is formed by drilling with a laser, and a resin-coated metal foil and an insulating film produced using the same. It is assumed that.

[0011]

The epoxy resin composition according to claim 1 of the present invention contains a novolak type epoxy resin and a crosslinked rubber having a particle diameter of 1 μm or less as essential components,
A novolak type epoxy resin is contained in an amount of 20 to 80 parts by mass based on 100 parts by mass of a solid content.

Further, the invention according to claim 2 comprises a novolak type epoxy resin, a crosslinked rubber having a particle diameter of 1 μm or less, and a polyvinyl acetal resin as essential components. 80
It is characterized by containing by mass.

According to a third aspect of the present invention, there is provided a metal foil with a resin, wherein the epoxy resin composition according to the first or second aspect is applied to the surface of the metal foil and is semi-cured. It is.

Further, an insulating film according to a fourth aspect of the present invention is characterized in that the epoxy resin composition according to the first or second aspect is semi-cured.

[0015]

Embodiments of the present invention will be described below.

In the present invention, as the epoxy resin, a novolak type epoxy resin is used, and specific examples thereof include a cresol novolak type epoxy resin and a phenol novolak type epoxy resin.
Further, a resin other than the novolak type epoxy resin can be used in combination. Examples of such a resin include a brominated bisphenol A type epoxy resin and a bisphenol F type epoxy resin.

The novolak type epoxy resin contains 20 to 80 parts by mass based on 100 parts by mass of the solid content in the epoxy resin composition described later. If the content is less than 20 parts by mass, a resin residue of the cured resin remains inside the hole processed by the laser, and the conduction reliability of the via hole (including the IVH of a multilayer printed wiring board or the like) is reduced. . Conversely, when the content exceeds 80 parts by mass, the hardened resin on the inner peripheral surface of the hole processed by the laser becomes difficult to be roughened by desmear treatment, and the hardened resin on the inner peripheral surface of the hole and the plating of copper or the like. As a result, sufficient adhesion strength cannot be obtained, and the conduction reliability of the via hole decreases.

In the present invention, the crosslinked rubber is not particularly limited as long as it is a fine particle rubber having a particle diameter of 1 μm or less, but the lower limit of the particle diameter is 0.01 μm.
m, and specific examples thereof include butadiene-acrylonitrile copolymer rubber and acrylonitrile rubber. Such a crosslinked rubber is preferably contained in the epoxy resin composition described later in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the resin, whereby the epoxy resin composition is good in a semi-cured state (B-stage). In addition to having high flexibility, tacking does not occur. When a non-crosslinked rubber is used instead of the crosslinked rubber, tacking occurs in a semi-cured state (B-stage), the glass transition temperature (Tg) decreases, and a crosslinked rubber having a particle diameter exceeding 1 μm is used. When rubber is used, agglomeration occurs in a varnish described later, and the agglomerated rubber remains even after drying, which hinders the formation of a circuit pattern.

It is preferable to add a polyvinyl acetal resin in addition to the above components. The polyvinyl acetal resin at this time is preferably contained in the epoxy resin composition described below in an amount of 1 to 20 parts by mass with respect to 100 parts by mass of the resin, whereby the epoxy resin composition in a semi-cured state (B-stage) is obtained. Flexibility is further enhanced, and cracks and peeling are less likely to occur.

In the present invention, the curing agent is not particularly limited, and examples thereof include dicyandiamide, phenol novolak, and acid anhydrides (trimellitic anhydride), which are general curing agents for epoxy resins. it can.

Further, if necessary, a curing accelerator and other additives can be used. Examples of the curing accelerator include imidazoles such as 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenyl-4-methylimidazole, dimethylbenzylamine, triethylenediamine, benzyldimethylamine, and triethanolamine. Amines, triphenylphosphine,
Organic phosphines such as diphenylphosphine and phenylphosphine; tetra-substituted phosphonium / tetra-substituted borate such as tetraphenylphosphonium / ethyltriphenylborate; 2-ethyl-4-methylimidazole;
Tetraphenylboron salts such as tetraphenylborate can be exemplified.

The epoxy resin composition according to the present invention comprises the novolak type epoxy resin described above and a particle diameter of 1 μm.
The following crosslinked rubber is used as an essential component, and if necessary, a polyvinyl acetal resin, a curing agent, and other additives are blended, and the mixture is uniformly mixed with a mixer, a blender, or the like. It is used as a varnish in the production of foils and insulating films. Note that this preparation was performed using methyl ethyl ketone (ME
It can be carried out using a solvent such as K), methoxypropanol (MP), dimethylformamide (DMF) or the like, or without using a solvent.

The metal foil with resin according to the present invention may be obtained by coating the above-mentioned epoxy resin on one surface of a metal foil such as a copper foil or an aluminum foil using a comma coater, a transfer coater, a curtain coater, a die coater or the like. Apply the composition,
By heating and drying this in a semi-cured state (B-stage) by heating it continuously or discontinuously, it is possible to produce a metal foil having a semi-cured resin layer formed on one surface. . Here, the thickness of the metal foil or the semi-cured resin layer formed on the surface of the metal foil can be appropriately selected, but the thickness of the metal foil is 8 to 80 μm, and the thickness of the semi-cured resin layer is 20 to 200 μm is common.

On the other hand, the insulating film according to the present invention is obtained by applying the above-mentioned epoxy resin composition to a carrier film such as a PET film using a comma coater, a transfer coater, a curtain coater, a die coater or the like. By heating and drying continuously or discontinuously to obtain a semi-cured state (B-stage), it is possible to produce a film in which a semi-cured resin is formed on a carrier film. Here, the thickness of the film-like semi-cured resin formed on the surface of the carrier film can be appropriately selected, and is generally 30 to 100 μm.

In the thus obtained resin-coated metal foil or insulating film, the epoxy resin composition contains a crosslinked rubber having a particle diameter of 1 μm or less, and further contains a polyvinyl acetal resin. The flexibility of semi-cured resin of resin-coated metal foil and insulating film is enhanced, and when handling metal foil with resin and insulating film, the semi-cured resin does not break or peel off, and resin powder etc. And the occurrence of tacking can be prevented. In addition, since the epoxy resin composition contains the novolak-type epoxy resin in the above-described content, the cured resin in which the epoxy resin composition is completely cured is less likely to generate a resin residue by laser processing. Even when laser drilling is performed on the multilayer wiring board, no resin residue remains inside the hole, and a via hole having good conductivity can be obtained.

Examples of the use of the above metal foil with resin include:
A semi-cured resin layer of metal foil with resin is overlaid on one or both sides of the inner layer substrate on which a circuit pattern has been formed as an inner layer circuit in advance, and this is heated and pressed to completely cure the semi-cured resin and cure the resin. Then, a multilayer wiring board for processing into a multilayer printed wiring board can be manufactured by laminating and molding. Then, a circuit pattern is formed on the metal foil of the resin-coated metal foil laminated on one or both surfaces of the multilayer wiring board by a subtractive method or the like, and an outer layer circuit is provided. To form a via hole, whereby a multilayer printed wiring board can be manufactured.

On the other hand, as an example of the use of the above-mentioned insulating film, a semi-cured resin of an insulating film is superimposed on one or both sides of an inner layer substrate on which a circuit pattern is formed as an inner layer circuit, and this is heated and heated. By pressing the semi-cured resin to completely cure the cured resin to form a cured resin, and laminating and molding, a multilayer wiring board for processing into a multilayer printed wiring board can be manufactured. Thereafter, the outer carrier film covering the insulating film laminated on one or both sides of the multilayer wiring board is peeled off, and a circuit pattern is formed on the exposed surface of the cured resin by an additive method or the like to form an outer layer circuit. The multilayer printed wiring board can be manufactured by forming a via hole by performing drilling with a laser and performing plating treatment with copper or the like while forming the hole.

In manufacturing a multilayer printed wiring board by processing the multilayer wiring board in this way, since the multilayer wiring board is made of the above-mentioned resin-coated metal foil or insulating film, voids are generated in the cured resin. This eliminates the problem that the metal foil to be removed by etching or the like at the time of forming a circuit pattern remains, and the deterioration of insulation properties and short-circuit failure can be prevented. Furthermore, in forming via holes by laser drilling, since the multilayer wiring board is made of the above-mentioned resin-coated metal foil and insulating film, no resin residue remains inside the holes after laser processing and conduction This makes it possible to obtain a via hole having good performance and improve the reliability of the multilayer printed wiring board.

[0029]

The present invention will be specifically described below with reference to examples.

As the epoxy resin, a brominated bisphenol A type epoxy resin ("YDB-50" manufactured by Toto Kasei Co., Ltd.)
0 ": epoxy equivalent 500, bromination ratio about 24 mass%),
Cresol novolak type epoxy resin ("YDCN-220" manufactured by Toto Kasei Co., Ltd .: epoxy equivalent 220, bromination ratio about 24 mass%) was used.

As the fine particle rubber, a crosslinked rubber of butadiene-acrylonitrile copolymer rubber (“XE” manufactured by JSR Corporation) is used.
R-91: particle size 0.5 μm or less), butadiene-acrylonitrile copolymer rubber crosslinked rubber (“X” manufactured by JSR Corporation)
ER-81 ": particle diameter 12 μm), non-crosslinked rubber (JSR
"N220S": particle size 5 m).

As the polyvinyl acetal resin, "6000AS" manufactured by Denki Kagaku Kogyo KK was used.

Further, dicyandiamide (molecular weight 84, theoretically active hydrogen equivalent 21) as a curing agent, 2-ethyl-4-methylimidazole as a curing accelerator, methyl ethyl ketone (MEK), methoxypropanol (MP), dimethylform as a solvent Amide (DMF) was used. <Preparation of Varnish of Epoxy Resin Composition> A fine particle rubber previously dispersed uniformly in dimethylformamide (DMF) at about 15% by mass and other components are mixed in a prescribed solvent (solid content) in the amounts shown in Tables 1 to 3. 40 parts by mass of methyl ethyl ketone (MEK), 20 parts by mass of methoxypropanol (MP), and dimethylformamide (DM
F) was added to a solvent prepared by mixing 40 parts by mass), and the mixture was mixed at about 1000 rpm with a “Homomixer” manufactured by Tokushu Kika Kogyo Co., Ltd.
m for about 90 minutes. Then, the curing accelerator (2-
Ethyl-4-methylimidazole) and add about 1
Stir for 5 minutes, then degas, at 500C for about 500-1
A varnish of 000 poise epoxy resin composition was prepared. <Preparation of metal foil with resin> A thickness of 0.01 as a metal foil
8mm copper foil ("GT" manufactured by Furukawa Circuit Foil)
Varnish of the epoxy resin composition prepared as described above is applied to the roughened surface of the copper foil with a comma coater at room temperature, and then, by a non-contact type heating unit, about 130 to 170 ° C. The solvent in the varnish is dried and removed by heating the epoxy resin composition, and the thickness of the semi-cured resin layer is 75 to 85.
A metal foil with a resin of μm was produced. <Preparation of insulating film> As a carrier film,
Using a PET film having a thickness of 0.035 mm,
A varnish of the epoxy resin composition prepared as described above is applied to the ET film at room temperature with a comma coater, and thereafter, by a non-contact type heating unit, about 130 to
By heating at 170 ° C., the solvent in the varnish was dried and removed, and the epoxy resin composition was semi-cured, whereby a semi-cured resin having a thickness of 75 to 85 μm was produced. <Evaluation items> 1. Rubber agglomeration in varnish The presence or absence of aggregation of the fine particle rubber in the varnish was visually inspected. 2. Resin crack angle First, the resin-attached metal foil 1 prepared as described above is cut into a width of 10 mm, and as shown in FIG. Cylindrical rod 4
(Diameter 10 mm) was placed and fixed so as to be substantially perpendicular to the longitudinal direction of the metal foil 1 with resin. Next, one of the metal foils 1 with resin is fixed in contact with the flat plate 3 via the cylindrical bar 4, and the metal foil 1 with resin is bent in the direction of the arrow so that the other is wound around the cylindrical bar 4. , The minimum angle θ (degree) at which a crack (crack) or the like occurs in the semi-cured resin is measured,
This was taken as the resin crack angle.

On the other hand, in the case of the insulating film 2, except that it is placed on the flat plate 3 with the carrier film side facing out,
The measurement was performed in the same manner as in the case of the metal foil 1 with resin. 3. Tacking Determines whether or not the glossy surface of the copper foil is stuck to the semi-cured resin to determine whether or not it is stuck. If it is stuck, "(Tacking) exists", and if it is not stuck, "No (Tacking)"
And 4. Laser workability As a substrate for the inner layer, a 0.2 mm thick inner layer core double-sided board ("CR1766" manufactured by Matsushita Electric Works: 35 μm thick copper foil), which has been subjected to an inner layer treatment (blackening treatment) on the surface copper foil in advance. Then, the metal foil with resin prepared as described above is superposed on both sides of the inner layer substrate on the side of the semi-cured resin layer,
While heating at 90 ° C. for 90 minutes, pressure was applied at 2.94 MPa to produce a multilayer wiring board. Thereafter, the copper foil on the surface was removed by etching to obtain a sample for laser processing.

On the other hand, in the case of an insulating film, the same kind of substrate for the inner layer as described above is used, and the insulating film prepared as described above is superposed on both sides of the substrate for the inner layer on the side of the semi-cured resin. 2.94MP while heating for 90 minutes
a to produce a multilayer wiring board. Thereafter, the carrier film on the surface was peeled off to obtain a sample for laser processing.

Next, a laser machine “ML50” manufactured by Mitsubishi Electric Corporation was used.
Using 5GT, under the conditions of pulse frequency: 1500 Hz, pulse width: 20 μs, output: 5.4 mj / pulse, irradiation pulse number: 3 shots, the laser processing sample obtained as described above was drilled. After performing, the inside of the hole was observed using a scanning electron microscope SEM, and the presence or absence of resin residue was investigated. 5. Continuity Reliability As a substrate for the inner layer, a daisy chain circuit pattern was previously formed on the copper foil on the surface, and an inner layer core double-sided plate (CR1766 manufactured by Matsushita Electric Works Co., Ltd.) with an inner layer treatment (blackening treatment) was applied. The thickness of the copper foil is 35 μm), and the metal foil with resin produced as described above is superposed on both sides of the inner layer substrate on the side of the semi-cured resin layer.
While heating at 90 ° C. for 90 minutes, pressure was applied at 2.94 MPa to produce a multilayer wiring board. Thereafter, an IVH was formed by laser processing, and an outer layer circuit was formed on the metal foil outside the multilayer wiring board, thereby forming a daisy chain pattern, and a sample for evaluating conduction reliability was obtained.

On the other hand, in the case of an insulating film, the same kind of substrate for the inner layer as described above is used, and the insulating film prepared as described above is superposed on both sides of the substrate for the inner layer on the side of the semi-cured resin. 2.94MP while heating for 90 minutes
a to produce a multilayer wiring board. After that, the carrier film on the surface is peeled off, and the IV
By forming H and forming an outer layer circuit on the surface of the cured resin outside the multilayer wiring board, a daisy chain pattern was formed, and a sample for evaluation of conduction reliability was obtained.

Next, the operation of leaving the sample for conduction reliability evaluation thus obtained in an atmosphere of -55 ° C. for 30 minutes and then in an atmosphere of 125 ° C. for 30 minutes was defined as one cycle. Was repeated 1000 cycles, and the presence or absence of disconnection was examined.

Tables 1 to 4 show the results of the above evaluation items 1 to 5.
Shown in

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

[0043]

[Table 4]

As can be seen from Tables 1 to 4, it is confirmed that the results of each of the examples are good in all evaluation items.

Moreover, comparing Examples 1 to 3 with Examples 4 to 6, the addition of the polyvinyl acetal resin increases the resin crack angle and makes cracks and the like less likely to occur. It is confirmed. This is also confirmed from a comparison between Examples 7 to 9 and Examples 10 to 12.

On the other hand, in the case of Comparative Examples 1 and 6, since non-crosslinked rubber was blended as fine particle rubber, it was confirmed that tacking was exhibited.

In Comparative Examples 2 and 7, the amount of the novolak-type epoxy resin was too small, so that it was confirmed that resin residues remained after laser processing and the conduction reliability was reduced.

Further, in the case of Comparative Examples 3 and 8, it was confirmed that the conduction reliability was lowered because the amount of the novolak type epoxy resin was too large.

The rubber composition of Comparative Example 4 has a particle diameter significantly exceeding 1 μm as a fine particle rubber (particle diameter: 12 μm).
It is confirmed that the rubber is agglomerated in the varnish because of the use of.

In the case of Comparative Example 5, the resin cracking angle was extremely small because no fine particle rubber was blended,
It is confirmed that cracks and the like easily occur.

[0051]

As described above, the epoxy resin composition according to the first aspect of the present invention contains a novolak-type epoxy resin and a crosslinked rubber having a particle diameter of 1 μm or less as essential components. Since it is contained in an amount of 20 to 80 parts by mass with respect to 100 parts by mass, the flexibility in a semi-cured state (B-stage) is enhanced by a crosslinked rubber having a particle diameter of 1 μm or less, and the cross-linked rubber may be broken as a semi-cured resin. It does not peel off, can reduce the generation of resin powder and the like, and can prevent the occurrence of tacking. Further, in the epoxy resin composition, a resin residue hardly occurs by laser processing in a cured state due to the novolak type epoxy resin.

The invention of claim 2 comprises a novolak type epoxy resin, a crosslinked rubber having a particle diameter of 1 μm or less, and a polyvinyl acetal resin as essential components. 80
Since it is contained in parts by mass, the flexibility in the semi-cured state (B-stage) is further enhanced by compounding a polyvinyl acetal resin in addition to the crosslinked rubber having a particle diameter of 1 μm or less, Cracks and peeling do not occur, and the generation of resin powder and the like can be further reduced, and the occurrence of tacking can be prevented. Further, in the epoxy resin composition, a resin residue hardly occurs by laser processing in a cured state due to the novolak type epoxy resin.

The resin-coated metal foil according to the third aspect of the present invention is obtained by applying the epoxy resin composition according to the first or second aspect to the surface of the metal foil and semi-curing. The semi-cured resin has increased flexibility, and when handling metal foil with resin, the semi-cured resin does not crack or peel off, reducing the generation of resin powder and the like and generating tacking. Can be prevented. Furthermore, the cured resin in which the semi-cured resin is completely cured has less resin residue due to laser processing, and even if a multilayer wiring board is drilled with a laser, no resin residue remains inside the hole, and good conductivity is obtained. Via holes can be obtained.

Further, the insulating film according to claim 4 of the present invention is obtained by semi-curing the epoxy resin composition according to claim 1 or 2, so that the semi-cured resin of the insulating film has enhanced flexibility. Therefore, when handling the insulating film, the semi-cured resin does not crack or peel off, so that the generation of resin powder and the like can be reduced and the occurrence of tacking can be prevented. Furthermore, the cured resin in which the semi-cured resin is completely cured has less resin residue due to laser processing, and even if a multilayer wiring board is drilled with a laser, no resin residue remains inside the hole, and good conductivity is obtained. Via holes can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a method for measuring a resin crack angle.

[Explanation of symbols]

 1 Metal foil with resin 2 Insulating film

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01B 3/40 H01B 3/40 CP 17/56 17/56 A F term (Reference) 4F071 AA10 AA30 AA42 AC12 AC15 AC17 AH12 AH13 BA02 BB02 BC02 4F100 AB01B AK23A AK53A AN00A BA02 BA07 DE01A GB43 JB15A JG04 JL01 JL11 JM02B YY00A 4J002 AC072 BE063 BG102 CD041 CD05 CD061 CD121 FA002 FD140 A03A15 A15G15 A15A15A15A15A15A15G15 BA03 CB04 CB06 DA03 DA04

Claims (4)

[Claims] 1. A novolak type epoxy resin having a particle size of 1
It contains a crosslinked rubber of μm or less as an essential component, and a novolak type epoxy resin having a solid content of 20 to 100 parts by mass.
An epoxy resin composition comprising 80 parts by mass. 2. A novolak type epoxy resin having a particle size of 1
An epoxy resin composition comprising a crosslinked rubber having a particle size of not more than μm and a polyvinyl acetal resin as essential components, and comprising 20 to 80 parts by mass of a novolak type epoxy resin per 100 parts by mass of a solid content. 3. A resin-coated metal foil, which is obtained by applying the epoxy resin composition according to claim 1 on the surface of the metal foil and semi-curing the epoxy resin composition. 4. An insulating film obtained by semi-curing the epoxy resin composition according to claim 1 or 2.