JP2025071393A - Resin composition, resin-coated copper foil and composite material - Google Patents

Abstract

[Problem] To provide a resin composition that enables bonding between copper foil and glass substrates by lamination and has excellent heat resistance. [Solution] The resin composition contains two or more polymers selected from the group consisting of polyamide resins, polyimide resins, and polyacrylic resins, one or more epoxy resins, and a curing agent, wherein at least one of the two or more polymers has a weight-average molecular weight of 50,000 or more, and at least one other polymer has a weight-average molecular weight of less than 50,000. [Selected Figures] None

Description

The present invention relates to a resin composition, a resin-coated copper foil, and a composite material.

Glass substrates are used for glass antennas that impart antenna functions to glass for automobiles and buildings, various flat panel displays, glass interposers, and the like. For example, Patent Document 1 (International Publication No. WO 2020/195661) discloses a resin composition intended for application to glass substrates, which comprises (a) an acrylic polymer having a tensile modulus of elasticity of 200 MPa or less, (b) a resin that is solid at 25°C, (c) a resin that is liquid at 25°C and can be crosslinked with at least one of the components (a) and (b), and (d) a polymerization initiator, and in which the content of the component (a) is 35 parts by weight or more and 93 parts by weight or less, the content of the component (b) is 3 parts by weight or more and 60 parts by weight or less, and the content of the component (c) is 1 part by weight or more and 25 parts by weight or less, relative to a total amount of 100 parts by weight of the components (a), (b), and (c).

In addition to the above-mentioned glass substrate, the resin composition is also used in various applications, for example, in electronic devices such as flexible printed wiring boards. For example, Patent Document 2 (JP 2007-168123 A) discloses a method for manufacturing a metal foil-attached flexible substrate in which a metal foil is provided on at least one side of a resin film, the method comprising a step of thermocompressing the metal foil to the resin film at 300°C or more and 500°C or less, the resin film containing a non-thermoplastic polyimide resin. Patent Document 3 (WO 2018/139559 A) discloses a curable resin composition that contains a curable resin, an imide oligomer having an imide skeleton in the main chain and a crosslinkable functional group at the end and a number average molecular weight of 4000 or less, and a curing accelerator, and in which the initial adhesive strength of the cured product to the polyimide is 3.4 N/cm or more, and the adhesive strength of the cured product to the polyimide after storage at 200°C for 100 hours is 0.8 times or more the initial adhesive strength. Patent Document 4 (JP Patent Publication 5-179220) discloses a heat-resistant adhesive that contains, as resin components, (A) 100 parts by weight of a soluble aromatic polyamideimide, (B) 25 to 300 parts by weight of an epoxy resin, and (C) an epoxy curing agent.

International Publication No. 2020/195661 JP 2007-168123 A International Publication No. 2018/139559 Japanese Patent Application Publication No. 5-179220

As mentioned above, resin compositions are used in various applications, but unlike applications such as laminating a resin material such as prepreg with a metal foil, as disclosed in Patent Documents 2 to 4, when laminating a metal foil (e.g., copper foil) with a glass substrate through a resin composition, problems specific to the application arise. For example, when a composite material is produced by laminating a copper foil with a glass substrate through a resin composition as a resin layer, if a press method is used, not only is it time-consuming and the size of the composite material itself is limited, but the glass substrate may also be broken. On the other hand, the lamination method is a method of laminating two or more sheets by roll-to-roll at a lower pressure than the press method, so continuous production is possible and the possibility of the glass substrate being broken is low. Therefore, when laminating a copper foil with a glass substrate through a resin composition as a resin layer, it is desirable to use the lamination method instead of the press method. However, although the lamination method has the above-mentioned advantages, it is difficult to increase the pressure to the same level as the press method, so a resin composition that enables adhesion of copper foil with a glass substrate by the lamination method is required. However, when a desired product is manufactured using such a resin composition, problems such as the generation of voids, phase separation of the resin, warping, and cracks may occur during lamination in the manufacturing process. Therefore, a resin composition that can solve these problems is required. In addition, such a resin composition is also required to have heat resistance that can withstand the high temperatures that are encountered during product manufacturing.

The present inventors have now discovered that a resin composition containing two or more polymers selected from polyamide resin, polyimide resin, and polyacrylic resin, an epoxy resin, and a curing agent, at least one of which has a weight average molecular weight of 50,000 or more and at least one of which has a weight average molecular weight of less than 50,000, enables bonding of copper foil and a glass substrate by a lamination method and also has excellent heat resistance.

Therefore, the object of the present invention is to provide a resin composition that enables bonding of copper foil and a glass substrate by a lamination method and has excellent heat resistance.

According to one aspect of the present invention,
Two or more polymers selected from the group consisting of polyamide resins, polyimide resins, and polyacrylic resins;
One or more epoxy resins;
A hardener;
Among the two or more polymers,
At least one of the polymers has a weight average molecular weight of 50,000 or more,
A resin composition is provided, wherein at least one of the other is a polymer having a weight average molecular weight of less than 50,000.

According to another aspect of the present invention,
A copper layer having a smooth surface with an aspect ratio Str of a surface property of 0.3 or more and 1 or less as measured in accordance with ISO 25178;
a resin layer formed on the smooth surface and composed of the resin composition;
The present invention provides a resin-coated copper foil comprising:

According to another aspect of the present invention,
A glass substrate;
the resin-coated copper foil being provided on at least one surface of the glass substrate such that the resin layer is in contact with the glass substrate;
A composite material is provided, comprising:

Resin composition The resin composition of the present invention contains two or more polymers selected from the group consisting of polyamide resins, polyimide resins, and polyacrylic resins, one or more epoxy resins, and a curing agent. At least one of the two or more polymers has a weight average molecular weight of 50,000 or more, and at least another has a weight average molecular weight of less than 50,000. In this way, the resin composition containing the two or more polymers, the epoxy resin, and the curing agent enables adhesion between copper foil and a glass substrate by a lamination method, and exhibits excellent heat resistance. And, the resin composition having excellent heat resistance can withstand high temperatures when manufacturing a product equipped with the resin composition.

As mentioned above, when a composite material is produced by bonding a copper foil and a glass substrate via a resin composition as a resin layer, a lamination method is desirable because it allows continuous production and is less likely to crack the glass substrate. However, although the lamination method has the above-mentioned advantages, it is difficult to increase the pressure as much as the press method, so a resin composition that enables adhesion of a copper foil and a glass substrate by the lamination method is required. However, when a desired product is produced using such a resin composition, problems such as void generation, resin phase separation, warping, and cracking may occur during lamination in the manufacturing process. In addition, the resin is usually not brought to the C stage by lamination alone, and additional heat treatment for main curing is required. Problems such as warping and cracking may also occur during this additional heat treatment. Furthermore, in the later process, a heating process may be performed for annealing (baking) or component mounting, and heat resistance that can withstand such high temperatures during manufacturing is also desired. In this regard, the resin composition of the present invention can conveniently solve the above problems. Here, the properties of the resin composition, such as heat resistance, can be determined, for example, by evaluating the storage modulus at 200°C in the C-stage state after curing, as well as the degree of void generation, adhesion and adhesive strength between the resin and the glass substrate or copper foil, and the degree of warping in a composite material in which copper foil and a glass substrate are bonded together via the resin composition.

The resin composition of the present invention preferably has a storage modulus of 10 MPa or more at 200°C in the C-stage state after curing, more preferably 30 MPa or more, and even more preferably 300 MPa or more. Such a high storage modulus can suppress deformation and cracking during heating of the resin composition, and can improve heat resistance. A high storage modulus at 200°C is preferable, and the upper limit is not particularly limited, but is typically 10,000 MPa or less, more typically 5,000 MPa or less, and even more typically 1,000 MPa or less. The storage modulus at 200°C is measured using a DMA (dynamic viscoelasticity measurement) device. Specifically, this DMA measurement is performed in accordance with JIS K 7244-4:1999, by placing a resin with a test piece width of 5.0 mm and a test piece thickness of 100 μm in a clamp with a clamp length of 20.0 mm, and heating it from 30°C to 280°C at a temperature increase rate of 5°C/min in an air atmosphere at a measurement frequency of 1 Hz.

The resin composition of the present invention contains two or more polymers selected from the group consisting of polyamide resins, polyimide resins, and polyacrylic resins. These polymers contribute to improving adhesion and storage modulus during lamination. The polyamide resin is not particularly limited as long as it is a polymer having an amide structure in the main chain, but from the viewpoint of using it in combination with an epoxy resin, a soluble polyamide is preferable, and more preferably a soluble polyamide having a functional group capable of reacting with an epoxy resin. The polyimide resin is not particularly limited as long as it is a polymer having an imide structure in the main chain, but from the viewpoint of using it in combination with an epoxy resin, a soluble polyimide is preferable, and more preferably a soluble polyimide having a functional group capable of reacting with an epoxy resin. Examples of polyacrylic resins include acrylic acid ester polymers and methacrylic acid ester polymers, and preferably have functional groups capable of reacting with an epoxy resin. Examples of functional groups capable of reacting with an epoxy resin include phenolic hydroxyl groups, amino groups (primary amines and secondary amines), carboxyl groups (including acid anhydrides), cyanate groups, mercapto groups, and the like.

The total content of two or more polymers selected from the group consisting of polyamide resins, polyimide resins, and polyacrylic resins is preferably 16 parts by weight or more and 70 parts by weight or less, more preferably 30 parts by weight or more and 68 parts by weight or less, even more preferably 33 parts by weight or more and 45 parts by weight or less, and particularly preferably 35 parts by weight or more and 42 parts by weight or less, relative to 100 parts by weight of the total amount of the resin composition.

Of these two or more polymers, it is preferable that at least one is a polyamide resin and at least one other is a polyimide resin. In this way, the above two or more polymers contain at least a polyamide resin and a polyimide resin, so that a wide temperature range in which lamination is possible can be ensured.

At least one of the two or more polymers selected from the group consisting of polyamide resins, polyimide resins, and polyacrylic resins is a polymer having a weight average molecular weight of 50,000 or more, and at least another is a polymer having a weight average molecular weight of less than 50,000. In this way, the two or more polymers contain a polymer having a weight average molecular weight of 50,000 or more, which can improve the brittleness of the resin composition after curing, but can also reduce lamination properties and adhesive strength. The two or more polymers contain a polymer having a weight average molecular weight of less than 50,000, which can improve lamination properties and adhesive strength, but can also reduce the storage modulus of the resin composition after curing. In other words, the two or more polymers contain a polymer having a weight average molecular weight of 50,000 or more and a polymer having a weight average molecular weight of less than 50,000, which can adjust the physical properties of the resin composition, and can particularly improve lamination properties and adhesive strength.

In addition, from the viewpoint of further adjusting the physical properties of the resin composition, the resin composition preferably contains 15 parts by weight or more and 70 parts by weight or less of a polymer having a weight average molecular weight of less than 50,000, relative to 100 parts by weight of the total amount of the resin composition, more preferably 20 parts by weight or more and 60 parts by weight or less, even more preferably 20 parts by weight or more and 50 parts by weight or less, and particularly preferably 20 parts by weight or more and 40 parts by weight or less. Furthermore, the resin composition preferably contains 1 part by weight or more and 20 parts by weight or less of a polymer having a weight average molecular weight of 50,000 or more, relative to 100 parts by weight of the total amount of the resin composition, more preferably 1 part by weight or more and 18 parts by weight or less, even more preferably 5 parts by weight or more and 18 parts by weight or less, and particularly preferably 5 parts by weight or more and 15 parts by weight or less.

The resin composition of the present invention contains one or more epoxy resins, and at least one of the one or more epoxy resins preferably has a naphthalene skeleton. The epoxy resin contributes to improving the lamination properties and storage modulus of the cured resin composition, and at least one of the epoxy resins has a naphthalene skeleton, which provides a higher storage modulus to the cured resin composition.

The total content of the one or more epoxy resins is preferably 30 parts by weight or more and 70 parts by weight or less, more preferably 35 parts by weight or more and 65 parts by weight or less, even more preferably 45 parts by weight or more and 65 parts by weight or less, and particularly preferably 50 parts by weight or more and 63 parts by weight or less, based on 100 parts by weight of the total amount of the resin composition.

で表される化合物等が挙げられる。ナフタレン骨格を有するエポキシ樹脂の市販例としては、ＤＩＣ株式会社製のＨＰ４７１０、ＨＰ４７７０、ＨＰ４０３２Ｄ、ＨＰ５０００及びＨＰ６０００、並びに日本化薬株式会社製のＮＣ７０００Ｈ及びＮＣ７３００Ｌが挙げられ、好ましくはビナフチル型エポキシ樹脂である。 Examples of epoxy resins having a naphthalene skeleton include, but are not limited to, those having a naphthalene skeleton, such as those having the following formula:

Examples of commercially available epoxy resins having a naphthalene skeleton include HP4710, HP4770, HP4032D, HP5000, and HP6000 manufactured by DIC Corporation, and NC7000H and NC7300L manufactured by Nippon Kayaku Co., Ltd., and are preferably binaphthyl-type epoxy resins.

The resin composition preferably contains 30 to 70 parts by weight of an epoxy resin having a naphthalene skeleton, more preferably 40 to 70 parts by weight, even more preferably 50 to 70 parts by weight, and most preferably 55 to 65 parts by weight, per 100 parts by weight of the total amount of the resin composition.

In addition, from the viewpoint of adjusting the functional group density, it is preferable that the one or more epoxy resins include two or more epoxy resins, at least one of which is an epoxy resin with a functional group number of 3 or more, and at least another of which is an epoxy resin with a functional group number of less than 3. It is also preferable that at least one of these two or more epoxy resins is an epoxy resin with a functional group number of 3 or more per molecule, and at least another of which is an epoxy resin with a functional group number of less than 3 per molecule. In this specification, the number of functional groups means the average number of functional groups per molecule present in the resin. For example, in a resin having a structure in which a repeating unit and a functional group is included in the repeating unit, it is difficult to make the number of repeating units (generally represented by n) of all molecules uniform in manufacturing, and molecules with different numbers of repeating units may be mixed. In that case, since molecules with different numbers of functional groups may be mixed, the sum of the number of functional groups x the existence ratio in the molecules present in the resin (i.e., the value obtained by averaging the number of functional groups by the existence ratio, and the total existence ratio is 1.) is used as the number of functional groups of the resin. For example, when the ratio of molecules having a functional group number of 2 in a resin is 0.5 and the ratio of molecules having a functional group number of 3 is 0.5, the number of functional groups of the resin is 2×0.5+3×0.5=2.5. By including an epoxy resin having a functional group number of 3 or more, the heat resistance of the resin composition after curing can be improved, but the resin composition after curing may become brittle. By including an epoxy resin having a functional group number of less than 3, the brittleness of the resin composition after curing can be improved, but the heat resistance of the resin composition after curing may decrease. That is, by including an epoxy resin having a functional group number of 3 or more and an epoxy resin having a functional group number of less than 3, the physical properties of the resin composition can be adjusted, and in particular, the heat resistance of the resin composition after curing can be secured while the brittleness can be improved. When the epoxy resin having a functional group number of 3 or more is a monomer, it preferably has a functional group number of 3 or more and 4 or less. Furthermore, when the epoxy resin has a large number of functional groups in the main chain, such as a novolac type, it is preferable that the number of functional groups is 3 or more and the functional group equivalent is 100 g/eq or more and 400 g/eq or less. Examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol E type epoxy resins, cresol novolac type epoxy resins, phenol novolac type epoxy resins, alkyl type epoxy resins, glycidylamine type epoxy resins, glycidyl ester type epoxy resins, phenol aralkyl type epoxy resins, trisphenol type epoxy resins, tetraphenylethane type epoxy resins, biphenyl type epoxy resins, bisphenol fluorene type epoxy resins, triazine type epoxy resins, isocyanurate type epoxy resins, alicyclic epoxy resins, heterocyclic epoxy resins, naphthol aralkyl type epoxy resins, naphthol novolac type epoxy resins, naphthol-phenol co-condensed novolac type epoxy resins, naphthol-cresol co-condensed novolac type epoxy resins, naphthalene type epoxy resins, naphthylene ether type epoxy resins, binaphthyl type epoxy resins, anthracene type epoxy resins, and the like. These epoxy resins having a functional number of epoxy groups of 3 or more and less than 3 can be used in combination.

The content of the epoxy resin having 3 or more functional groups is preferably 15 parts by weight or more and 70 parts by weight or less, more preferably 20 parts by weight or more and 50 parts by weight or less, even more preferably 25 parts by weight or more and 45 parts by weight or less, and particularly preferably 30 parts by weight or more and 40 parts by weight or less, based on 100 parts by weight of the total amount of the resin composition. The content of the epoxy resin having less than 3 functional groups is preferably 10 parts by weight or more and 65 parts by weight or less, more preferably 12 parts by weight or more and 50 parts by weight or less, even more preferably 14 parts by weight or more and 40 parts by weight or less, and particularly preferably 16 parts by weight or more and 30 parts by weight or less, based on 100 parts by weight of the total amount of the resin composition.

The resin composition of the present invention contains a curing agent. The curing agent contributes to promoting the crosslinking reaction between the two or more polymers and one or more epoxy resins, and to the reaction between epoxy resins. The curing agent is not particularly limited as long as it can promote the epoxy reaction, but preferred examples include imidazole-based curing agents and phosphorus-based curing agents.

The content of the curing agent is preferably 0.3 parts by weight or more and 10 parts by weight or less, more preferably 1.0 parts by weight or more and 5.0 parts by weight or less, and even more preferably 2.0 parts by weight or more and 4.0 parts by weight or less, based on 100 parts by weight of the total amount of the resin composition.

Resin-Coated Copper Foil The resin composition of the present invention is preferably used as a resin layer of a resin-coated copper foil. By forming the resin-coated copper foil in advance, it is possible to efficiently manufacture a member having a glass substrate without separately forming a resin layer. That is, according to a preferred embodiment of the present invention, a resin-coated copper foil is provided, which comprises a copper layer having a smooth surface with an aspect ratio Str of the surface property measured in accordance with ISO25178 of 0.3 to 1, and a resin layer composed of a resin composition provided on the smooth surface. Typically, the resin composition is in the form of a resin layer, and the resin composition is applied to the copper foil (copper layer) using a bar coater so that the thickness of the resin layer after drying is a predetermined value, and then dried to obtain a resin-coated copper foil. The coating method is arbitrary, but can be applied using a doctor blade or a bar coater, and can also be a gravure coating method, a die coating method, a knife coating method, or the like.

The copper foil may be a metal foil (so-called raw foil) that has been electrolytically or rolled, or may be in the form of a surface-treated foil that has been surface-treated on at least one side. The surface treatment may be any of a variety of surface treatments that are performed to improve or impart certain properties to the surface of the metal foil (e.g., rust resistance, moisture resistance, chemical resistance, acid resistance, heat resistance, and adhesion to a substrate). The surface treatment may be performed on at least one side of the metal foil, or on both sides of the metal foil. Examples of surface treatments performed on copper foil include rust prevention treatment, silane treatment, roughening treatment, and barrier formation treatment.

The copper layer has a smooth surface from the viewpoint of downsizing (miniaturization) of the circuit. The aspect ratio Str of the surface texture is an index for judging the smoothness of the copper layer surface. The aspect ratio Str of the surface texture is an index that indicates the anisotropy of the surface height (presence or absence of places where there is a sudden change). The closer Str is to 0, the more anisotropic it is, and the closer Str is to 1, the less anisotropic it is. In the case of bonding ultra-smooth glass and a copper layer, it is preferable that the Str of the copper layer surface is close to 1 (no anisotropy) from the viewpoint of reducing bonding defects. From this viewpoint, it is preferable that the aspect ratio Str of the surface texture of the copper layer is 0.3 or more and 1 or less, more preferably 0.4 or more and 1 or less, even more preferably 0.5 or more and 1 or less, and particularly preferably 0.6 or more and 1 or less.

The maximum height Sz of the surface of the copper layer on the side in contact with the resin layer is preferably 6.8 μm or less, more preferably 0.15 μm to 6.8 μm, even more preferably 0.25 μm to 5.0 μm, and particularly preferably 0.3 μm to 3.0 μm. Within this range, the resin layer conforms appropriately to ensure sufficient adhesion between the copper layer and the glass substrate. In this specification, the "maximum height Sz" is a parameter that represents the distance from the highest point to the lowest point on the surface, measured in accordance with ISO 25178.

The maximum peak height Sp on the surface of the copper layer that contacts the resin layer is preferably 3.3 μm or less, more preferably 0.06 μm or more and 3.1 μm or less, even more preferably 0.06 μm or more and 3.0 μm or less, and particularly preferably 0.07 μm or more and 2.9 μm or less. Within such a range, the resin layer can conform appropriately to ensure sufficient adhesion between the copper layer and the glass substrate. In this specification, the "maximum peak height Sp" is a three-dimensional parameter that represents the maximum value of the height from the average plane of the surface, measured in accordance with ISO25178.

The root-mean-square gradient Sdq on the surface of the copper layer in contact with the resin layer is preferably 0.01 to 2.3, more preferably 0.02 to 2.0, and even more preferably 0.04 to 1.8. Within such a range, the resin layer can follow suit to ensure sufficient adhesion between the copper layer and the glass substrate. In this specification, the "root-mean-square gradient Sdq" is a parameter calculated from the root-mean-square of the slope at all points in the defined area measured in accordance with ISO25178. In other words, since it is a three-dimensional parameter that evaluates the magnitude of the local slope angle, it can quantify the steepness of the surface unevenness. For example, the Sdq of a completely flat surface is 0, and if the surface is inclined, the Sdq becomes large. The Sdq of a plane consisting of a 45-degree slope component is 1.

The above-mentioned Str, Sz, Sp and Sdq can be measured using a commercially available laser microscope (e.g., OLS5000 manufactured by Olympus Corporation) in accordance with ISO25178 and according to the procedures shown in the examples.

The thickness of the copper layer is preferably 5 μm or less, more preferably 0.5 μm to 4 μm, even more preferably 1 μm to 4 μm, and particularly preferably 1 μm to 3 μm. With such a thickness, it is possible to reduce circuit thinning such as undercut when cutting a fine pattern circuit. However, when using such a thin copper layer, it is preferable to provide a carrier layer on the side opposite the smooth side of the copper layer in order to improve the handleability of the resin-coated copper foil. That is, it is preferable that a copper layer (ultra-thin copper foil) having a thickness of 5 μm or less is provided in the form of a carrier-coated copper foil. Therefore, according to a preferred embodiment of the present invention, a resin-coated copper foil is provided in which the copper layer has a thickness of 5 μm or less and further includes a carrier layer on the side opposite the smooth side of the copper layer. In addition, for circuit formation, a copper layer of a desired thickness can be further formed on the copper layer, typically using a known method such as copper plating.

The thickness of the resin layer is not particularly limited, but is preferably 1 μm to 10 μm, more preferably 2 μm to 8 μm, even more preferably 2 μm to 7 μm, and particularly preferably 3 μm to 7 μm. With such a thickness, the above-mentioned characteristics of the present invention can be more effectively realized, and the resin layer can be easily formed by applying the resin composition. Furthermore, handling properties are improved.

Composite material The resin composition of the present invention is preferably used as a resin layer of a composite material comprising a glass substrate and a resin-coated copper foil. That is, according to a preferred embodiment of the present invention, a composite material is provided comprising a glass substrate and a resin-coated copper foil provided on at least one surface of the glass substrate so that the resin layer is in contact with the glass substrate. As described above, when a composite material is produced by bonding a copper foil and a glass substrate via a resin composition as a resin layer, a lamination method is desirable because it allows continuous production and has a low possibility of cracking the glass substrate. However, although the lamination method has the above-mentioned advantages, it is difficult to increase the pressure as much as the pressing method, and it is difficult to ensure the adhesion between the copper foil and the glass substrate. Therefore, by using the resin composition of the present invention as a resin layer, the copper foil and the glass substrate can be bonded by the lamination method, and the composite material can be efficiently produced.

The present invention will be further illustrated by the following examples.

Examples 1 to 11
(1) Preparation of Varnish First, the resin components shown below were prepared as raw materials for the varnish.
(a1) Polyimide resin having a molecular weight of less than 50,000:
- Polyimide A (weight average molecular weight less than 50,000) manufactured by JFE Chemical Corporation
- Polyimide B (weight average molecular weight less than 50,000) manufactured by JFE Chemical Corporation
- PIAD300 (Arakawa Chemical Industries, Ltd., medium molecular weight thermoplastic polyimide, weight average molecular weight less than 50,000)
(a2) Polyamide resin having a molecular weight of 50,000 or more:
- DAN1 (manufactured by Nippon Kayaku Co., Ltd., weight average molecular weight of 50,000 or more)
(a3) Acrylic resin having a molecular weight of 50,000 or more:
- SG-P3 (Nagase ChemteX Corporation, functional group: epoxy, weight average molecular weight 50,000 or more)
(b1) Epoxy resin having three or more functional groups:
- HP4710 (having naphthalene skeleton) (manufactured by DIC Corporation, number of functional groups: 3 or more, epoxy equivalent: 170 g/eq)
- EPPN502H (no naphthalene skeleton) (manufactured by Nippon Kayaku Co., Ltd., functional group number: 3 or more, epoxy equivalent: 158 g/eq or more and 178 g/eq or less)
(b2) Epoxy resin having a functionality of less than 3:
- HP4770 (having naphthalene skeleton) (manufactured by DIC Corporation, number of functional groups: less than 3, epoxy equivalent: 160 g/eq or more and 170 g/eq or less)
- NC3000H (no naphthalene skeleton) (manufactured by Nippon Kayaku Co., Ltd., number of functional groups: less than 3, epoxy equivalent: 280 g/eq or more and 300 g/eq or less)
(c1) Imidazole-based curing agent:
- TBZ (manufactured by Shikoku Chemical Industry Co., Ltd.)
- 2P4MHZ (manufactured by Shikoku Chemical Industry Co., Ltd.)

Each raw material component and organic solvent were weighed and placed in a flask so as to obtain the compounding ratio (parts by weight) and solid content concentration (% by weight) shown in Tables 1 and 2. The flask was heated to 60°C with a mantle heater while stirring with a stirring blade, and each raw material component was dissolved in the solvent, and then cooled to room temperature to obtain a varnish. At this time, for Examples 1 to 5 and 8 to 11 in which polyamide resin (DAN1) was used as a raw material component for the varnish, DAN1 was added to cyclopentanone solvent in advance to prepare a solution with a solid content concentration of 20%, and this solution was added to a separately prepared solution in which the other components had been dissolved and cooled to room temperature so as to obtain the compounding ratio (parts by weight) of DAN1 shown in Tables 1 and 2, and the mixture was stirred to obtain a varnish.

(2) Preparation of Dilute Varnish A portion of the obtained varnish was set aside, and cyclopentanone was added as a dilution solvent to give a diluted solids concentration (wt %) shown in Tables 1 and 2, followed by stirring to obtain a diluted varnish.

(3) Preparation of resin film The varnish obtained in (1) above was applied to a fluororesin film (manufactured by AGC Corporation, Aflex (registered trademark)) and air-dried for 15 seconds, then placed in an oven preheated to 150°C and heated and dried for 5 minutes. In this way, a resin layer with Aflex was obtained. At this time, the coating conditions were adjusted so that the thickness of the resin layer after drying (not including the thickness of the Aflex) was 20 μm. The Aflex was peeled off from the obtained resin layer with Aflex, and five sheets of only the resin layer were laminated. The obtained resin laminate was held in a vacuum press at 220°C and 40 kgf/ ^cm2 for 90 minutes to be cured, and a resin film was obtained.

(4) Preparation of resin-coated copper foil An electrolytic copper foil (manufactured by Mitsui Mining & Smelting Co., Ltd.) having a thickness of 2 μm and a smooth surface with a surface property aspect ratio Str of 0.39, a maximum height Sz of 0.81, a maximum peak height Sp of 0.40, and a root-mean-square gradient Sdq of 0.22 was prepared. The surface property aspect ratio Str, maximum height Sz, maximum peak height Sp, and root-mean-square gradient Sdq were measured by surface roughness analysis using a laser microscope (manufactured by Olympus Corporation, OLS5000) in accordance with ISO25178 as follows. First, the surface profile of an area of 16384 μm ² on the smooth surface of the copper foil was measured using a 100x objective lens with the above laser microscope under the conditions of scanning mode "3D standard + color" and shooting mode "Auto". The obtained surface profile of the smooth surface was subjected to noise removal to remove spike noise, and tilt removal was automatically performed, after which the aspect ratio Str of the surface property was measured by surface property analysis. At this time, shape removal was performed by F calculation (selecting "multiple surface cubic"), and the cutoff wavelength by the S filter was set to 0.55 μm, and the cutoff wavelength by the L filter was set to 10 μm. The above Str, Sz, Sp, and Sdq were measured in eight different fields of view, and the average values of Str, Sz, Sp, and Sdq in all fields of view were adopted as the values of the smooth surface of the sample.

The diluted varnish obtained in (2) above was applied to the smooth surface of the copper foil using a bar coater, and then placed in an oven preheated to 150°C and dried for 2 minutes to obtain a resin-coated copper foil. The coating conditions were adjusted so that the thickness of the resin layer after drying would be 5 μm.

(5) Lamination with glass substrate The resin-coated copper foil obtained in (4) above was cut into a square of 10.5 cm x 10.5 cm. The cut resin-coated copper foil was placed on a 0.5 mm thick glass substrate (Corning, alkali-free glass, Eagle XG) measuring 10 cm x 10 cm so that the resin surface was in contact with the glass substrate, and laminated using a vacuum laminator. This lamination was performed by holding the laminate under conditions of 170 ° C and 0.95 MPa after evacuation for 20 seconds. In this way, a composite material after lamination comprising a glass substrate and a resin-coated copper foil was obtained.

(6) Main curing: The laminated composite material obtained in (5) above was subjected to additional heat treatment to complete the curing, and a fully cured (C-stage) composite material comprising a glass substrate and a resin-coated copper foil was obtained. The additional heat treatment was performed by placing the composite material in an oven preheated to 230° C. and holding it there for 30 minutes.

(7) Various Evaluations The produced resin films and composite materials were evaluated as follows.

<Storage modulus>
A 5 mm x 50 mm rectangular sample was cut out from the resin film obtained in (3) above, and a DMA (dynamic viscoelasticity measurement) measurement was performed using a DMA (dynamic viscoelasticity measurement) device (Hitachi High-Tech Science, DMA7100). This measurement was performed in accordance with JIS K 7244-4:1999, by placing a resin with a test piece width of 5.0 mm and a test piece thickness of 100 μm in a clamp with a clamp-to-clamp length of 20.0 mm, and heating it from 30 ° C. to 280 ° C. at a temperature increase rate of 5 ° C./min in an air atmosphere, at a measurement frequency of 1 Hz. The obtained measurement data was analyzed, and the storage modulus E' (MPa) at 200 ° C. was calculated and evaluated according to the following criteria. The results were as shown in Tables 3 and 4.
- Rating AA: 300 MPa or more - Rating A: 30 MPa or more and less than 300 MPa - Rating B: 10 MPa or more and less than 30 MPa - Rating C: less than 10 MPa

<Lamination properties (presence or absence of voids)>
The composite material obtained in (5) above was visually observed from its glass surface to check for the presence or absence of voids and was evaluated according to the following criteria. The results are shown in Tables 3 and 4.
- Rating A: No voids were visible - Rating B: Voids were visible - Rating C: The resin-coated copper foil was not attached to the glass substrate

<Lamination properties (void occupancy rate)>
The composite material obtained in (5) above was photographed from its glass surface using an optical microscope (Keyence, VHX7100). The photographed image was imported into image analysis software ImageJ (free software) and analyzed, and the ratio (%) of the void area to the photographed image area was calculated and evaluated according to the following criteria. The results are shown in Tables 3 and 4.
- Grade A: The void area ratio is less than 1%. - Grade B: The void area ratio is 1% or more. - Grade C: The resin-coated copper foil is not attached to the glass substrate.

<Lamination properties (adhesion)>
When the composite material obtained in (5) above was handled (transported for the main curing in (6) above), it was checked whether the resin and/or copper foil peeled off from the glass (whether it was possible to handle it), and was evaluated according to the following criteria. The results are shown in Tables 3 and 4.
- Evaluation A: No peeling occurred, and handling was possible without any problems. - Evaluation B: Peeling of less than 1 mm in width occurred between the glass and resin at the edge of the sample due to handling. - Evaluation C: Peeling of 1 mm in width or more occurred between the glass and resin at the edge of the sample due to handling.

<Adhesive strength>
The composite material obtained in (6) above was copper plated to form copper wiring with a wiring width of 10 mm and a wiring thickness of 20 μm by a subtractive method, and the adhesive strength (peel strength) was measured in accordance with JIS C 6481. The measurement was performed five times, and the average value was taken as the adhesive strength value and evaluated according to the following criteria. The adhesive strength measured here is a value that reflects three failure modes: interfacial peeling between glass and resin, cohesive failure in the resin, and interfacial peeling between resin and copper foil, and the higher the value, the better the adhesion to glass, the strength of the resin layer, and the adhesion to low roughness foil. The results were as shown in Tables 3 and 4.
- Grade AA: Adhesive strength is 1.0 kgf/cm or more - Grade A: Adhesive strength is 0.5 kgf/cm or more and less than 1.0 kgf/cm - Grade B: Adhesive strength is 0.1 kgf/cm or more and less than 0.5 kgf/cm - Grade C: Adhesive strength is less than 0.1 kgf/cm

＜Warping＞
The composite material obtained in (6) above was used to measure the amount of warping of the substrate using a 3D heating surface profiler (Thermoray PS200S, manufactured by Akrometrix). The amount of warping was calculated from the difference between the maximum and minimum values of the Z coordinate of the glass laminate. The measurement was performed five times in an atmosphere of 27°C, and the average value of the obtained measurements was taken as the warping, and was evaluated according to the following criteria. The results are shown in Tables 3 and 4.
- Rating A: Warpage is less than 500 μm - Rating C: Warpage is 500 μm or more

Claims (11)

Two or more polymers selected from the group consisting of polyamide resins, polyimide resins, and polyacrylic resins;
One or more epoxy resins;
A hardener;
Among the two or more polymers,
At least one of the polymers has a weight average molecular weight of 50,000 or more,
A resin composition, wherein at least one other of the resins is a polymer having a weight average molecular weight of less than 50,000. The resin composition according to claim 1, wherein at least one of the epoxy resins has a naphthalene skeleton. The epoxy resin contains two or more epoxy resins, and among the two or more epoxy resins,
At least one of the epoxy resins has a functionality of 3 or more,
The resin composition according to claim 1 or 2, wherein at least one of the other resins is an epoxy resin having a functionality of less than 3. Among the two or more polymers,
At least one of the resins is a polyamide resin,
The resin composition according to any one of claims 1 to 3, wherein at least one of the other resins is a polyimide resin. The resin composition according to any one of claims 2 to 4, comprising 30 parts by weight or more and 70 parts by weight or less of the epoxy resin having a naphthalene skeleton relative to 100 parts by weight of the total amount of the resin composition. The resin composition according to any one of claims 1 to 5, comprising 15 parts by weight or more and 70 parts by weight or less of the polymer having a weight average molecular weight of less than 50,000 relative to 100 parts by weight of the total amount of the resin composition. The resin composition according to any one of claims 1 to 6, comprising 1 part by weight or more and 20 parts by weight or less of the polymer having a weight average molecular weight of 50,000 or more per 100 parts by weight of the total amount of the resin composition. The resin composition according to any one of claims 1 to 7, wherein the storage modulus at 200°C in a C-stage state after curing is 10 MPa or more. A copper layer having a smooth surface with an aspect ratio Str of a surface property of 0.3 or more and 1 or less as measured in accordance with ISO 25178;
A resin layer formed on the smooth surface and composed of the resin composition according to any one of claims 1 to 8;
The resin-coated copper foil is provided with: The thickness of the copper layer is 5 μm or less, and a carrier layer is further provided on the surface of the copper layer opposite to the smooth surface.
The resin-coated copper foil according to claim 9. A glass substrate;
The resin-coated copper foil according to claim 9 or 10, wherein the resin layer is provided on at least one surface of the glass substrate so as to be in contact with the glass substrate;
A composite material comprising: