Resin film, multilayer wiring board, copper foil with resin, coil structure, and magnetic device

Abstract

To provide a resin film capable of preventing interlayer delamination even under high-temperature thermal treatment.SOLUTION: Provided is a resin film 100 comprising a core layer 2 and adhesive resin layers 1 provided on both surfaces of the core layer 2, wherein each adhesive resin layer 1 is composed of an adhesive resin composition, and the minimum viscosity of the adhesive resin composition from 40°C to 160°C as measured with a rheometer is 500 Pa s or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a resin film, a multilayer wiring board, a copper foil with resin, a coil structure, and a magnetic device.

Background Art

[0002] As a thin transformer which is one of magnetic devices, for example, Patent Document 1 describes a thin transformer including a printed coil and a core made of a magnetic material, and a pedestal with terminals on which the printed coil and the core are mounted. This thin transformer is characterized in that the surface where the conductor of the printed coil is exposed is covered with a heat-resistant resin.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in recent years, magnetic devices have been required to handle higher voltages and larger currents. Therefore, in order to surely ensure the insulation of the heat-resistant resin layer, for example, it is conceivable to use an interlayer insulating material having a three-layer structure including an adhesive resin layer provided on both surfaces of the core layer. However, it has been found that when a multilayer wiring board using such an interlayer insulating material is subjected to a reflow process, there is a risk of delamination.

[0005] An object of the present invention is to provide a resin film capable of suppressing the occurrence of delamination even when subjected to high-temperature heat treatment, and a multilayer wiring board, a copper foil with resin, a coil structure, and a magnetic device using the same.

Means for Solving the Problems

[0006] According to the present invention, there are provided a resin film, a multilayer wiring board, a copper foil with resin, a coil structure, and a magnetic device as described below. [1] A resin film comprising a core layer and adhesive resin layers provided on both sides of the core layer, respectively, wherein the adhesive resin layer is made of an adhesive resin composition, and the minimum viscosity of the adhesive resin composition measured by a rheometer from a temperature of 40°C to 160°C is 500 Pa·s or more. Resin film. [2] In the resin film according to [1], the adhesive resin composition contains an epoxy resin, an aromatic amine-based curing agent, and a solvent-soluble polyimide resin. Resin film. [3] In the resin film according to [1] or [2], the core layer is made of a polyimide film. Resin film. [4] In the resin film according to any one of [1] to [3], the viscosity of the adhesive resin composition measured by a rheometer at a temperature of 60°C is 5×10 5 Pa·s or more. Resin film. [5] A multilayer wiring board comprising an insulating layer formed using the resin film according to any one of [1] to [4]. Multilayer wiring board. [6] A copper foil with resin comprising the resin film according to any one of [1] to [4] and a copper foil laminated on the resin film. Copper foil with resin. [7] A coil structure comprising an insulating layer formed using the resin film according to any one of [1] to [4]. Coil structure. [8] A magnetic device comprising an insulating layer formed using the resin film according to any one of [1] to [4]. Magnetic device.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide a resin film capable of suppressing the occurrence of delamination even when subjected to high-temperature heat treatment, and a multilayer wiring board, a copper foil with resin, a coil structure, and a magnetic device using the same.

Brief Description of Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] Hereinafter, the present invention will be described based on the drawings by taking embodiments as examples. The present invention is not limited to the contents of the embodiments. In the drawings, there are parts illustrated with enlargement or reduction for ease of explanation.

[0010] [Resin Film] As shown in FIG. 1, the resin film 100 according to the present embodiment includes a core layer 2, an adhesive resin layer 1, and a release film layer 3. The adhesive resin layer 1 is provided on both sides of the core layer 2, respectively. A release film layer 3 is provided on the adhesive resin layer 1. When using the resin film 100, the release film layer 3 is peeled off from the adhesive resin layer 1 and used. And the adhesive resin layer 1 is composed of an adhesive resin composition. Further, in this adhesive resin composition, the minimum viscosity measured with a rheometer from a temperature of 40°C to 160°C needs to be 500 Pa·s or more. The reason why the resin film 100 according to the present embodiment can suppress the occurrence of delamination even when subjected to high-temperature heat treatment is as follows. That is, the inventors speculated that the occurrence of delamination when manufacturing the multilayer wiring board 200 (see FIG. 3) using the resin film 100 is affected by the viscosity change when the adhesive resin composition cures. The adhesive resin composition becomes softer as the temperature increases, but hardens due to heat. The inventors found that delamination occurs when the minimum viscosity at that time is too low. As a result of intensive research, it was found that the occurrence of delamination can be suppressed by using an adhesive resin composition having a minimum viscosity of 500 Pa·s or more measured with a rheometer from a temperature of 40°C to 160°C.

[0011] The minimum viscosity from a temperature of 40°C to 160°C is preferably 1000 Pa·s or less, and particularly preferably 800 Pa·s or less. If the minimum viscosity is below the above upper limit, the adhesiveness of the adhesive resin composition and the like can be improved. From the same viewpoint, the temperature at which the minimum viscosity is reached is preferably 130°C or higher and 150°C or lower, and particularly preferably 135°C or higher and 145°C or lower. Also, the viscosity at a temperature of 60°C is preferably 5×10 5 Pa·s or more and 5×10 6 Pa·s or less, and particularly preferably 1×10 6 Pa·s or more and 3×10 6 Pa·s or less. If this viscosity is above the above lower limit, the occurrence of delamination can be more reliably suppressed.

[0012] The viscosity of the adhesive resin layer 1 can be measured as follows. That is, first, as a sample, the adhesive resin composition of the adhesive resin layer 1 is collected from the resin film 100. The collected adhesive resin composition is put into a rheometer (device name: "HAAKE MARS III", manufactured by Thermo Fisher Scientific), and the viscosity of the adhesive resin composition is measured when the temperature is changed from 40 °C to 160 °C under the conditions of a heating rate of 2.5 °C / min and a frequency of 1.0 Hz while vibrating the rotation of the plate left and right.

[0013] Examples of methods for adjusting the minimum viscosity of the adhesive resin composition and the degree of viscosity change to the above-mentioned ranges include the following methods. The minimum viscosity and the degree of viscosity change, etc., can be adjusted by changing the type or blending amount of the resin and the curing agent, or by changing the degree of B-stage (semi-curing) of the adhesive resin composition.

[0014] (Adhesive resin layer) The adhesive resin layer 1 is a layer made of an adhesive resin composition. The adhesive resin layer 1 may be formed by applying a coating liquid for the adhesive resin composition and drying it. Further, the adhesive resin composition may be B-staged (semi-cured) by heat. The coating liquid for the adhesive resin composition preferably contains an epoxy resin, an aromatic amine-based curing agent, and a solvent-soluble polyimide resin. By B-staging this adhesive resin composition, the minimum viscosity can be easily adjusted within the above-mentioned range. In addition, the coating liquid for the adhesive resin composition may contain a filler, a curing accelerator, a flame retardant, a solvent, etc., as necessary.

[0015] Any epoxy resin having two or more glycidyl groups can be used. Preferred epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, novolac phenol type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, dicyclopentadiene type epoxy resins, and the like. These may be used alone or in combination of two or more.

[0016] The aromatic amine curing agent is not particularly limited as long as it has an aromatic group and an amino group and has the effect of promoting the curing of the epoxy resin upon light irradiation. Examples of the aromatic group include a phenyl group, a biphenyl group, and a fluorenyl group. Examples of the aromatic amine curing agent include 4,4'-diaminodiphenyl sulfone, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(4-aminophenoxy)phenyl]sulfone, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, trimethylene bis(4-aminobenzoate), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, bis[4-(3-aminophenoxy)phenyl]sulfone, 9,9'-bis(4-aminophenyl)fluorene, and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane. These may be used alone or in combination of two or more.

[0017] When the number of moles of the epoxy resin is 1, the amount of the aromatic amine curing agent used is preferably 0.3 mol or more and 1.5 mol or less. When the amount used is not less than the lower limit, it tends to be easy to obtain an appropriate thermal expansion coefficient. On the other hand, when the amount used is not more than the upper limit, it tends to be easy to obtain an appropriate Tg and thermal expansion coefficient.

[0018] A solvent-soluble polyimide resin is a polyimide resin that is soluble in the solvent used for manufacturing the adhesive resin composition according to this embodiment. As the solvent-soluble polyimide resin, those having characteristics such as high Tg, low coefficient of thermal expansion, excellent film physical properties, low dielectric constant, and low dielectric tangent are preferable. Examples of the solvent-soluble polyimide resin include a completely imidized soluble polyimide resin obtained by reacting diaminotrimethylphenylindane with benzophenone tetracarboxylic dianhydride. This compound can improve the adhesive strength without using an adhesion promoter in combination. The number average molecular weight (Mn) of the solvent-soluble polyimide resin is not particularly limited, but is preferably 10,000 or more and 50,000 or less, and particularly preferably 12,000 or more and 20,000 or less.

[0019] When the total amount of the epoxy resin and the aromatic amine-based curing agent is 100 parts by mass, the blending amount of the solvent-soluble polyimide resin is preferably 10 parts by mass or more and 100 parts by mass or less, and particularly preferably 15 parts by mass or more and 100 parts by mass or less. If the blending amount is equal to or more than the lower limit, the effect of improving the adhesive strength and flexibility is likely to be obtained. Also, if the blending amount is equal to or less than the upper limit, the breaking strength as a film tends to be ensured.

[0020] Examples of the filler include silica, alumina, aluminum hydroxide, magnesium hydroxide, etc. These may be used alone or in combination of two or more. Examples of the curing accelerator include imidazoles, etc. These may be used alone or in combination of two or more. Examples of the flame retardant include condensed phosphate esters, phosphazenes, polyphosphates, and HCA (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) derivatives, etc. These may be used alone or in combination of two or more. Examples of the solvent include NMP (N-methylpyrrolidone), diethylene glycol monomethyl ether acetate, cyclohexanone, and MEK (methyl ethyl ketone). These may be used alone or in combination of two or more.

[0021] The thickness of the adhesive resin layer 1 varies according to the copper thickness of the wiring board to be joined and is not particularly limited. For example, when the copper thickness of the wiring board is 35 μm, the thickness of the adhesive resin layer 1 is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 70 μm or less, still more preferably 20 μm or more and 50 μm or less, and particularly preferably 30 μm or more and 40 μm or less. If the thickness is below the upper limit, the thickness of the resin film 100 can be made thinner. If the thickness is above the lower limit, the adhesiveness of the resin film 100 can be improved.

[0022] (Core layer) The core layer 2 is the core layer at the center of the three-layer resin film 100. By this core layer 2, it is possible to prevent the occurrence of resin bleeding or the like during thermocompression bonding when manufacturing a multilayer wiring board or the like using the resin film 100. The core layer 2 preferably comprises a resin film having excellent heat resistance. Examples of such resin films include polyimide films, polyetherimide films, polyamide films, polyamideimide films, polymethylpentene films, polyester films, polyetheretherketone films, liquid crystal polymer films, polyphenylene ether films, polyphenylene sulfide films, polyolefin films, syndiotactic polystyrene-based films, fluorine-based resin films, and cycloolefin polymer films. Among these, a polyimide film is preferred from the viewpoint of good compatibility with the adhesive resin layer 1.

[0023] The thickness of the core layer 2 varies depending on the configuration of the wiring substrate to be joined and is not particularly limited. For example, the thickness of the core layer 2 is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 50 μm or less, and particularly preferably 20 μm or more and 30 μm or less. If the thickness is below the upper limit, the thickness of the resin film 100 can be made thinner. If the thickness is above the lower limit, the insulation of the resin film 100 can be improved.

[0024] (Release film layer) The release film layer 3 is a layer made of a release film provided on the adhesive resin layer 1. When using the resin film 100, the release film layer 3 can be peeled off from the adhesive resin layer 1 and used. Also, since a coating liquid for the adhesive resin composition can be applied on the release film layer 3 to form a film and B-staged, the adhesive resin layer 1 can be easily formed. Note that the release film layer 3 does not necessarily have to be provided. The release film layer 3 is a member provided as needed. Examples of the release film include a polyethylene terephthalate film (PET film) and a polyethylene naphthalate film. A release treatment may be applied to the surface of the release film.

[0025] [Manufacturing method of resin film] The manufacturing method of the resin film 100 according to the present embodiment is not particularly limited. For example, as shown in FIG. 2, the resin film 100 includes a film-forming step of applying a coating liquid for the adhesive resin composition on the release film layer 3 to form a coating film 1b, and a drying step of drying the coating film 1b formed in the film-forming step to form the adhesive resin layer 1 to obtain an adhesive laminated film, and a laminating step of sandwiching and laminating the core layer 2 with two adhesive laminated films obtained in the drying step to obtain the resin film 100.

[0026] In the film-forming step, as shown in FIG. 2(A), a coating liquid for the adhesive resin composition is applied on the release film layer 3 to form a film. Examples of the coating device for the adhesive resin composition include a bar coater, a curtain coater, a spray coater, a roll coater, and a screen printing machine. The coating thickness of the adhesive resin composition is preferably adjusted so that the thickness of the adhesive resin layer 1 falls within the above-described range.

[0027] In the drying step, as shown in FIG. 2(B), the coating film 1b formed in the film forming step is dried to form the adhesive resin layer 1, thereby obtaining the adhesive laminated film. The drying temperature is preferably 100°C or higher and 160°C or lower, more preferably 105°C or higher and 155°C or lower, and particularly preferably 110°C or higher and 150°C or lower. If the temperature is within the above range, the adhesive resin composition can be appropriately B-staged, and the minimum viscosity of the adhesive resin composition can be adjusted to a suitable range. The drying time is preferably 10 seconds or longer and 600 seconds or shorter, more preferably 15 seconds or longer and 500 seconds or shorter, and particularly preferably 30 seconds or longer and 500 seconds or shorter. If the time is within the above range, the adhesive resin composition can be appropriately B-staged, and the minimum viscosity of the adhesive resin composition can be adjusted to a suitable range.

[0028] In the lamination step, as shown in FIG. 2(C), the core layer 2 is sandwiched and laminated between two adhesive laminated films obtained in the drying step to obtain the resin film 100. Here, the core layer 2 is sandwiched between two adhesive laminated films such that the release film layer 3 of the adhesive laminated film is on the outside. Since the adhesive resin layer 1 has adhesiveness, the resin film 100 can be obtained. Examples of the lamination include vacuum pressure lamination, vacuum roll lamination, and roll lamination. As described above, the resin film 100 according to the present embodiment can be manufactured.

[0029] [Multilayer Wiring Substrate] The multilayer wiring board 200 according to this embodiment includes an insulating layer formed using the resin film 100 according to the foregoing embodiment. This insulating layer has a three-layer structure and can suppress the occurrence of delamination even when subjected to high-temperature heat treatment. The multilayer wiring board 200 can be manufactured, for example, by a method including a release film removing step of removing the release film layer 3 from the resin film 100 as shown in FIG. 3, a lamination step of sandwiching the resin film 100 from which the release film layer 3 has been removed between two single-layer wiring boards 4 to obtain a wiring laminate, and a thermosetting step of subjecting the adhesive resin layer 1 of the wiring laminate obtained in the lamination step to a thermosetting treatment to obtain the multilayer wiring board 200.

[0030] In the release film removing step, as shown in FIG. 3(A), the release film layer 3 is removed from the resin film 100. The release film layer 3 is for protecting the adhesive resin layer 1 until use and can be removed by peeling it from the adhesive resin layer 1.

[0031] In the lamination step, as shown in FIG. 3(B), the resin film 100 from which the release film layer 3 has been removed is sandwiched between two single-layer wiring boards 4 to obtain a wiring laminate. The single-layer wiring board 4 includes a base material 41 and wirings 42. The single-layer wiring board 4 may be a double-sided board having wirings 42 on both sides or a single-sided board. Here, the resin film 100 from which the release film layer 3 has been removed is sandwiched between two single-layer wiring boards 4. Since the adhesive resin layer 1 has adhesiveness, a wiring laminate can be obtained.

[0032] In the thermosetting step, the adhesive resin layer 1 of the wiring laminate obtained in the lamination step is subjected to a thermosetting treatment to obtain the multilayer wiring board 200. The adhesive resin layer 1 becomes a cured resin layer 1a made of a cured product of the adhesive composition by the thermosetting treatment. Examples of the thermosetting treatment include a heat press treatment and a heat treatment. The thermosetting treatment may be a single-step treatment or a multi-step treatment of two or more steps. The temperature of the thermosetting treatment is preferably 150°C or higher and 200°C or lower, and particularly preferably 170°C or higher and 190°C or lower. The pressure of the thermosetting treatment is preferably 0.1 MPa or higher and 10 MPa or lower, and particularly preferably 0.5 MPa or higher and 4 MPa or lower. The time of the thermosetting treatment is preferably 0.5 hours or longer and 4 hours or shorter, and particularly preferably 1 hour or longer and 3 hours or shorter.

[0033] As described above, the multilayer wiring board 200 according to this embodiment can be manufactured. Even when an electronic component is mounted on the wiring 42 of this multilayer wiring board 200 and a reflow treatment is performed, the occurrence of delamination can be suppressed.

[0034] [Copper foil with resin] The copper foil with resin according to this embodiment (not shown) includes the resin film 100 according to the above-described embodiment (at least one release film layer 3 removed) and a copper foil laminated on the resin film 100. According to this copper foil with resin, another wiring can be built up on the wiring of the wiring board via an insulating layer. The copper foil may be laminated on one side of the resin film 100 or may be laminated on both sides of the resin film 100.

[0035] [Coil structure and magnetic device] The coil structure according to this embodiment (not shown) includes an insulating layer formed using the resin film 100 according to the above-described embodiment. This coil structure can be manufactured by the same method as the multilayer wiring board 200 according to the above-described embodiment. That is, a coil structure can be manufactured by using a wiring board having a coil-shaped wiring as the single-layer wiring board 4. The magnetic device according to this embodiment (not shown) includes an insulating layer formed using the resin film 100 according to the above-described embodiment. This magnetic device can be manufactured in the same manner as the multilayer wiring board 200 according to the above-described embodiment. That is, as the single-layer wiring board 4, a wiring board having a coiled wiring can be used to manufacture a coil structure. And a device including this coil structure and a core is the magnetic device according to the present embodiment. As the core, a known one can be used, such as ferrite.

[0036] [Modifications of the Embodiment] The present invention is not limited to the above-described embodiment, and modifications or improvements within the scope that can achieve the object of the present invention are included in the present invention. For example, in the above-described embodiment, the multilayer wiring board 200 is formed by bonding two single-layer wiring boards 4 using a resin film 100, but it is not limited thereto. For example, the multilayer wiring board 200 may include three or more single-layer wiring boards 4. Further, the multilayer wiring board 200 may be provided with an FR-4 base material or the like on the outermost layer to improve the strength.

Examples

[0037] Next, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by these examples.

[0038] [Preparation Example 1] A mixture consisting of 453 parts by mass of bisphenol A type epoxy resin "Epiclon 850-S" (manufactured by DIC Corporation, epoxy equivalent: 188), 247 parts by mass of aromatic amine-based curing agent "BAPP" (manufactured by Wakayama Seika Kogyo Co., Ltd., 2,2-bis[4-(4-aminophenoxy)phenyl]propane), 1500 parts by weight of soluble polyimide resin "Q-VR-X0163" (manufactured by PI Technology Research Institute, resin solid content 20% by mass), and 0.7 parts by mass of 2-ethyl-4-methylimidazole was prepared to obtain a resin varnish having a resin solid content of 46% by mass.

[0039] [Example 1] On a release film (PET film subjected to a release treatment), the resin varnish obtained in Preparation Example 1 was applied and dried at 110 °C for 300 seconds to produce a PET film with an adhesive resin layer. The thickness of the adhesive resin layer was 36 μm. Two sheets of this PET film with an adhesive resin layer were arranged such that the adhesive resin layers faced each other, and a core layer (polyimide film, thickness: 25 μm) was sandwiched between them, and they were laminated using a roll laminator under the conditions of a peak actual temperature of 111 °C and a roll speed of 0.35 m / min to produce a resin film. Next, two FR-4 substrates (base material thickness: 0.4 mm) having test patterns (copper foil thickness: 35 μm) were prepared. The two FR-4 substrates were arranged such that the test patterns faced each other. Then, the release film was removed from the obtained resin film, sandwiched between the FR-4 substrates, and subjected to a hot press treatment to produce a multilayer wiring board. The conditions of the hot press treatment were 30 minutes at a set temperature of 150 °C and a pressure of 0.5 MPa in the first stage, and 70 minutes at a set temperature of 190 °C and a pressure of 2 MPa in the second stage.

[0040] [Comparative Example 1] A resin film and a multilayer wiring board were produced in the same manner as in Example 1, except that the lamination conditions in the roll laminator were changed to a peak actual temperature of 95 °C and a roll speed of 0.5 m / min.

[0041] [Evaluation of Resin Film] The evaluation of the resin film (viscosity of the adhesive resin composition, swelling after reflow) was performed by the following method. The obtained results are shown in Table 1. (1) Viscosity of Adhesive Resin Composition The adhesive resin composition of the adhesive resin layer was collected from the obtained resin film. The collected adhesive resin composition was put into a rheometer (device name "HAAKE MARS III", manufactured by Thermo Fisher Scientific), and the viscosity of the adhesive resin composition was measured when the temperature was changed from 40 °C to 170 °C under the conditions of a heating rate of 2.5 °C / min and a frequency of 1.0 Hz while vibrating the rotation of the plate left and right. The obtained results are shown in Figure 4. Also, from the graph shown in FIG. 4, the minimum viscosity (unit: Pa·s) from a temperature of 40°C to 160°C and the temperature at that time were read. Also, the viscosity (unit: Pa·s) at a temperature of 60°C was read. (2) Swelling after reflow The obtained multilayer wiring board was put into a reflow furnace (manufactured by Tamura Seisakusho) and reflow processing was performed. The reflow conditions were that the preheat temperature was 140°C to 160°C (for about 120 seconds), the time at a temperature of 220°C or higher was about 100 seconds, and the peak temperature was 260°C. Then, the multilayer wiring board after reflow was observed, and the swelling after reflow was evaluated according to the following criteria. ○: No swelling occurred. ×: Swelling occurred.

[0042]

Table 1

[0043] As is clear from the results shown in Table 1 and FIG. 4, when the minimum viscosity measured by the rheometer from a temperature of 40°C to 160°C is 500 Pa·s or more (Example 1), it was confirmed that the result of the swelling after reflow was good. Therefore, according to the resin film of the present invention, it was confirmed that the occurrence of delamination can be suppressed even when subjected to high-temperature heat treatment.

Explanation of reference numerals

[0044] 1... Adhesive resin layer 1a... Cured resin layer 1b... Coating film 2... Core layer 3... Release film layer 4... Single-layer wiring board 41... Base material 42... Wiring 100... Resin film 200... Multilayer wiring board

Claims

1. A resin film comprising a core layer and adhesive resin layers provided on both sides of the core layer, wherein the adhesive resin layer is composed of an adhesive resin composition, and the minimum viscosity of the adhesive resin composition measured by a rheometer from a temperature of 40°C to 160°C is 500 Pa·s or more. Resin film.

2. The resin film according to Claim 1, wherein the adhesive resin composition contains an epoxy resin, an aromatic amine-based curing agent, and a solvent-soluble polyimide resin. Resin film.

3. The resin film according to Claim 1 or Claim 2, wherein the core layer is made of a polyimide film. Resin film.

4. The resin film according to Claim 1 or Claim 2, In the adhesive resin composition, the viscosity measured by a rheometer at a temperature of 60°C is 5 × 10 ５ Pa·s or more, Resin film.

5. A multilayer wiring board comprising an insulating layer formed using the resin film according to Claim 1 or Claim 2. Multilayer wiring board.

6. A copper foil with resin, comprising the resin film according to Claim 1 or Claim 2 and a copper foil laminated on the resin film. Copper foil with resin.

7. A coil structure comprising an insulating layer formed using the resin film according to Claim 1 or Claim 2. Coil structure.

8. A magnetic device comprising an insulating layer formed using the resin film according to Claim 1 or Claim 2. Magnetic device.

Images