Film for electronic devices and printed circuit board

Abstract

To provide a film for an electronic apparatus and a printed circuit board that secures heat resistance and adhesion in an assembly process to achieve a low dielectric constant and a dielectric tangent.SOLUTION: A film for an electronic apparatus has a film-like-formed main material a compound dispersed in the main material. The compound is a homopolymer of a monomer unit represented by formula (1) or a copolymer of a plurality of kinds of monomer units, and a weight average molecular weight of the compound is from 1000 to 20000, inclusive. In the formula (1), R1 and R2 are each independently selected from a group composed of a hydrogen atom and a hydrocarbon group having 1 to 30 carbon atoms or jointly form an alkylidene group. R3 and R4 are each independently selected from a group composed of a hydrogen atom and a hydrocarbon group having 1 to 30 carbon atoms or jointly form an alkylidene group.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a film for electronic devices and a printed circuit board. [Background technology]

[0002] Printed circuit boards are widely used for applications such as high-frequency devices. A printed circuit board typically has a flat plate structure in which an insulating substrate material, copper foil, and a coating material are laminated, and the substrate material and the coating material are mainly composed of a resin material. When mounting such a printed circuit board in an electronic device, various elements are connected to the wiring (copper foil) provided on the printed circuit board by a method such as soldering.

[0003] When soldering is performed in the mounting stage as described above, the printed circuit board is temporarily exposed to high temperatures (e.g., 250°C). Therefore, the resin material used in the printed circuit board is required to have a certain level of heat resistance. For example, liquid crystal polymers are used as insulating materials having such heat resistance (Patent Document 1, Patent Document 2). Also, materials having adhesive properties are used to bond such insulating materials to metals that form the circuit (Patent Document 3, Patent Document 4). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-65061 A [Patent Document 2] International Publication No. 2020 / 179443 [Patent Document 3] JP 2020-90564 A [Patent Document 4] Patent Publication No. 2021-66865 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to improve the performance of a printed circuit board, it is preferable to use a material with a low dielectric constant and dielectric loss tangent. However, due to requirements in the assembly process, the heat resistance and adhesiveness of the material are given priority, and there are cases where a material with a relatively high dielectric constant and dielectric loss tangent must be used. Therefore, there is room for improvement in the performance of printed circuit boards.

[0006] Therefore, there is a demand for a simple means for improving the electrical properties of insulating materials and adhesive materials that are conventionally used, as well as for realizing films and printed circuit boards for electronic devices that incorporate such a means. [Means for solving the problem]

[0007] The film for electronic devices according to the present invention comprises at least one kind of main material formed into a film shape and a compound dispersed in the main material, the compound being a homopolymer of a monomer unit represented by formula (1) or a copolymer of a plurality of kinds of the monomer units, and the weight-average molecular weight of the compound is 1,000 or more and 20,000 or less. [ka]

[0008] In the formula, R 1 and R 2 are each independently selected from the group consisting of a hydrogen atom and a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, or together form an alkylidene group, R 3 and R 4 are each independently selected from the group consisting of a hydrogen atom and a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, or together form an alkylidene group.

[0009] A printed circuit board according to the present invention is characterized by including the above-mentioned film for electronic devices.

[0010] According to these configurations, the electrical properties of the above-mentioned compound can be reflected in the performance of the film for electronic devices and the printed circuit board without significantly impairing the preferable physical properties of the main material, and thus it is possible to provide a film for electronic devices and a printed circuit board in which the electrical properties of the insulating material and the adhesive material used in the past are improved by a simple method.

[0011] Preferred embodiments of the present invention will be described below. However, the scope of the present invention is not limited to the preferred embodiments described below.

[0012] In one embodiment of the film for electronic devices according to the present invention, the compound is represented by the formula (1), 1 , R 2 , R 3 , and R 4 are preferably hydrogen atoms.

[0013] According to this configuration, the film for electronic devices according to the present invention can be provided using unsubstituted norbornene, which is relatively easily available, as a raw material.

[0014] In one embodiment of the film for electronic devices according to the present invention, the compound is preferably the copolymer.

[0015] According to this configuration, the heat resistance, flexibility, and bending resistance of the film for electronic devices are likely to be at levels particularly suitable for printed circuit boards. In addition, the physical properties of the compound can be easily adjusted by changing the ratio of the copolymerized monomer units.

[0016] In one embodiment, the film for electronic devices according to the present invention has particles dispersed in the main material, and the particles preferably contain the compound.

[0017] This configuration makes it easy to disperse the compound in the main material.

[0018] In one embodiment, the film for electronic devices according to the present invention comprises an adhesive layer having adhesion to metal and an insulating layer at least partially covering the adhesive layer, and it is preferable that the main material is an insulating material, and that in the insulating layer, the compound is dispersed in the main material.

[0019] According to this configuration, in contrast to the conventional adhesive layer in which it was difficult to achieve both electrical properties and adhesiveness, the dielectric constant and dielectric dissipation factor of the adhesive layer can be reduced by reflecting the electrical properties of the compound, thereby reducing the dielectric constant and dielectric dissipation factor of the entire film.

[0020] In one embodiment, the film for electronic devices according to the present invention comprises an adhesive layer having adhesion to metal and an insulating layer at least partially covering the adhesive layer, and it is preferable that the main material is a material having adhesion to metal, and that in the adhesive layer, the compound is dispersed in the main material.

[0021] According to this configuration, the electrical properties of the insulating layer can be improved without changing the basic design of an existing film for electronic devices having an insulating layer and an adhesive layer, or with minimal changes.

[0022] Further features and advantages of the present invention will become more apparent from the following description of exemplary and non-limiting embodiments, which are given with reference to the drawings. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic cross-sectional view showing a structure of a film for electronic devices according to a first embodiment. [Diagram 2] FIG. 4 is a schematic cross-sectional view showing a structure of a film for electronic devices according to a second embodiment. [Diagram 3] This is the first example of a wide-angle X-ray scattering profile of a film for electronic devices. [Figure 4] This is a second example of a wide-angle X-ray scattering profile of a film for electronic devices. [Diagram 5] FIG. 2 is a schematic cross-sectional view showing a structure of a printed circuit board. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An embodiment of a film for electronic devices and a printed circuit board according to the present invention will be described with reference to the drawings. In the following, an example in which the film for electronic devices according to the present invention is applied to a film for electronic devices for a printed circuit board 1 will be described. In this specification, two embodiments of the film for electronic devices (a film for electronic devices 10 (FIG. 1) and a film for electronic devices 20 (FIG. 2)) will be described as an embodiment of the film for electronic devices, and matters other than those clearly stated as individual descriptions of each embodiment are common to both embodiments. Note that when both embodiments are referred to collectively, they will be referred to as a film for electronic devices without being given a reference symbol.

[0025] [Structure of Compound I] The film for electronic devices according to the present embodiment includes at least one main material formed into a film shape and a compound (hereinafter, referred to as compound I) dispersed in the main material. Compound I is a homopolymer of a monomer unit represented by formula (1) or a copolymer of a plurality of kinds of the monomer units. [ka]

[0026] In formula (1), R 1 and R 2 are each independently selected from the group consisting of a hydrogen atom and a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, or together form an alkylidene group, R 3 and R 4 are each independently selected from the group consisting of a hydrogen atom and a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, or together form an alkylidene group. Therefore, compound I is a homopolymer or copolymer having a polynorbornene skeleton. In addition, terminal functional groups derived from the polymerization initiator are present at both ends of the polynorbornene skeleton.

[0027] Compound I is represented by the formula (1) 1 , R 2 , R 3 , and R 4 is a hydrogen atom. This monomer unit is, in other words, an unsubstituted norbornene unit.

[0028] Compound I is R 2 , R 3 , and R 4 are all hydrogen atoms, and R 1 is any one selected from the group consisting of an alkyl group, an alkenyl group, and a cycloalkyl group; and 3 and R 4 are all hydrogen atoms, and R 1 and R 2 and a monomer unit which combines with each other to form an alkylidene group. These monomer units are, in other words, substituted norbornene units. The alkyl group, alkenyl group, cycloalkyl group, and alkylidene group preferably have 20 or less carbon atoms.

[0029] The alkyl group is not particularly limited, and may be a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, or an alkyl group having a longer chain length. However, the number of carbon atoms in the alkyl group is preferably 4 or more, more preferably 6 or more. The number of carbon atoms in the alkyl group is preferably 20 or less, more preferably 10 or less, and even more preferably 8 or less.

[0030] The above alkenyl group is not particularly limited, and may be an allyl group, a vinyl group, an ethynyl group, a propenyl group, a butenyl group, or an alkenyl group having a longer chain length. In an alkenyl group having 3 or more carbon atoms, the position and number of double bonds are not limited. However, the number of carbon atoms in the alkenyl group is preferably 2 or more, and more preferably 6 or more. In addition, the number of carbon atoms in the alkenyl group is preferably 20 or less, more preferably 10 or less, and even more preferably 8 or less.

[0031] The cycloalkyl group is not particularly limited, and may be a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, or a cycloalkyl group having a larger number of carbon atoms. However, the number of carbon atoms in the cycloalkyl group is preferably 4 or more, more preferably 6 or more. The number of carbon atoms in the cycloalkyl group is preferably 20 or less, more preferably 10 or less, and even more preferably 8 or less.

[0032] The alkylidene group is not particularly limited, and may be an ethylidene group, a propylidene group, a butylidene group, or an alkylidene group having a longer chain length. However, the number of carbon atoms in the alkylidene group is preferably 2 or more, and more preferably 6 or more. The number of carbon atoms in the alkylidene group is preferably 20 or less, more preferably 10 or less, and even more preferably 8 or less.

[0033] Compound I may be, for example, a copolymer represented by the following formula (2) (hereinafter referred to as copolymer II). Copolymer II contains two types of monomer units. The first monomer unit is the unsubstituted norbornene unit described above, and the second monomer unit is the substituted norbornene unit described above. Copolymer II contains the first monomer unit and the second monomer unit in a molar ratio of n:m. [ka]

[0034] When compound I is copolymer II, the ratio of the first monomer unit (unsubstituted norbornene unit) to the second monomer unit (substituted norbornene unit) is not particularly limited, and therefore the combination of n and m in formula (2) is arbitrary. The combination of n and m is preferably such that m / (n+m) is 0.05 or more (substituted norbornene unit is 5 mol% or more), more preferably 0.1 or more. In addition, the combination of n and m is preferably such that m / (n+m) is 0.99 or less, more preferably 0.8 or less, even more preferably 0.5 or less, and particularly preferably 0.3 or less.

[0035] The weight-average molecular weight of the compound I is 1000 or more and 20000 or less. In the electronic device film according to this embodiment, the compound I is dispersed in the main material. When the weight-average molecular weight of the compound I is 20000 or less, the compound I is easily uniformly dispersed in the main material. In addition, when the weight-average molecular weight of the compound I is such a relatively low value, the compound I is easily dissolved in an organic solvent such as toluene, decane, cyclohexane, or cyclohexanone, or is easily uniformly dispersed in these solvents, so that a liquid-liquid mixture of a solution containing the compound I and a solution (varnish) containing the main material can be performed, and thus a uniform dispersion state of the compound I is easily realized. In addition, when the weight-average molecular weight of the compound I is 20000 or less, the phenomenon that the compound I gels in an organic solvent can also be suppressed. From the viewpoint of dispersibility, the weight-average molecular weight of the compound I is preferably 10000 or less, more preferably 5000 or less.

[0036] In addition, when the weight-average molecular weight of compound I is 1000 or more, the heat resistance and electrical properties of the compound of formula (1) are easily reflected in the performance of the film for electronic devices. From the viewpoint of heat resistance and electrical properties, the weight-average molecular weight of compound I is preferably 2000 or more, and more preferably 3000 or more.

[0037] The weight average molecular weight of Compound I can be determined by a method such as gel permeation chromatography.

[0038] [Method for producing compound I] Compound I can be obtained by a known polymerization reaction using the corresponding monomer as a starting material. That is, the monomer unit represented by formula (1) (one type in the case of a homopolymer, multiple types in the case of a copolymer) is reacted in a reaction solvent in the presence of a polymerization catalyst and a chain transfer agent. The reaction temperature is not particularly limited, but can be, for example, 25 to 200°C.

[0039] The reaction solvent is not particularly limited, and may be, for example, one or a mixture of two or more selected from ketone-based solvents, ether-based solvents, ester-based solvents, acyclic aliphatic alcohol-based solvents, aromatic solvents, and the like.

[0040] The polymerization catalyst is not particularly limited, and may be, for example, a palladium complex or a nickel complex. The ligands contained in these complexes may be phosphine-based, diimine-based, and nitrile-based ligands. A counter anion may also be contained. The polymerization catalyst may be one type or a mixture of multiple types. The amount of catalyst used may be, for example, 1 ppmmol or more and 1000 ppmmol or less relative to the monomer.

[0041] The palladium complex is not particularly limited, and examples thereof include allylpalladium complexes such as palladium(II)(acetonitrile)bis(triisopropylphosphine)acetate tetrakis(2,3,4,5,6-pentafluorophenyl)borate and π-allylpalladium chloride dimer; organic carboxylates of palladium such as acetate, propionate, maleate, and naphthoate of palladium; and organic carboxylates of palladium such as triphenylphosphine complex of palladium acetate, tri(m-tolyl)phosphine complex of palladium acetate, tricyclohexylphosphine complex of palladium acetate, and triisopropylphosphine complex of palladium acetate. , organic sulfonates of palladium such as dibutyl phosphite and p-toluenesulfonate of palladium, β-diketone compounds of palladium such as palladium bis(acetylacetonate), bis(hexafluoroacetylacetonate), palladium bis(ethylacetoacetate), and palladium bis(phenylacetoacetate), and halide complexes of palladium such as dichlorobis(triphenylphosphine)palladium, bis[tri(m-tolylphosphine)]palladium, dibromobis[tri(m-tolylphosphine)]palladium, and acetonyltriphenylphosphonium complexes.

[0042] The phosphine ligand is not particularly limited, but can be triphenylphosphine, dicyclohexylphenylphosphine, cyclohexyldiphenylphosphine, tricyclohexylphosphine, and the like.

[0043] The chain transfer agent is not particularly limited, but may be, for example, a trialkylsilane compound such as trimethylsilane, triethylsilane, or tributylsilane, or a cyclobutene compound such as bicyclo[4.2.0]oct-7-ene.

[0044] After the reaction, compound I can be isolated by a known method, however, compound I may be used in the next step without isolation if it does not interfere with the next step.

[0045] [Physical properties of compound I] In the electronic device film according to the present embodiment, the 5% weight loss temperature of compound I measured by thermogravimetry (TG) at a heating rate of 5°C / min according to JIS K 7120-1987 is preferably 300°C or higher. When the 5% weight loss temperature of compound I is 300°C or higher, it is easy to achieve a level of heat resistance required for electronic device applications. For example, when the electronic device film according to the present embodiment is used for an electronic substrate, it is required to have heat resistance that can withstand soldering performed on the substrate. The 5% weight loss temperature of compound I is more preferably 350°C or higher.

[0046] In the electronic device film according to the present embodiment, the dielectric constant of compound I measured at a frequency of 10 GHz according to JIS C 2565-1992 is preferably 3.0 or less. When the dielectric constant of compound I is 3.0 or less, the signal transmission speed is increased in the high-frequency device using the electronic device film according to the present embodiment, so that the film can be particularly suitably used in electronic devices for high-speed communication. The dielectric constant of compound I is more preferably 2.5 or less.

[0047] In the electronic device film according to the present embodiment, the dielectric loss tangent of compound I measured at a frequency of 10 GHz according to JIS C 2565-1992 is preferably 0.003 or less. When the dielectric loss tangent of compound I is 0.003 or less, the signal loss is suppressed in the high-frequency device using the electronic device film according to the present embodiment, so that the film can be particularly suitably used in electronic devices for high-speed communication. The dielectric loss tangent of compound I is more preferably 0.002 or less.

[0048] A wide-angle X-ray scattering (WAXS) profile was measured for a sample of compound I molded into a film using the "BL03XU Beamline X-ray Scattering Measurement System" test equipment installed at SPring8 (Japan Synchrotron Radiation Research Institute), with a detector "Pilatus 1M," a camera distance of 0.3 m, an X-ray exposure time of 5 s, and one accumulation. X-rays with a wavelength of 0.1 nm were incident perpendicularly to the film sample surface. The measured wide-angle X-ray scattering profile showed that the scattering vector q was 2 nm -1 8nm or more -1 The first region below, and 10 nm -1 More than 20nm -1 The scattering pattern was evaluated in the range of the second region below. The scattering vector q is given by the following formula (3): where λ is the wavelength of the X-ray used in the measurement, and 2θ is the scattering angle.

number

[0049] The scattering vector q of compound I preferably has at least one peak in the range of the first region. It is more preferable that the scattering vector q of compound I has at least one peak in each of the ranges of the first region and the second region. It is more preferable that the scattering vector q of compound I has at least two peaks in the range of the first region.

[0050] The peaks in the first region are derived from the crystalline portion of compound I. Therefore, the positions, intensities, and number of peaks appearing in the first region vary depending on the crystal structure of compound I. Such a crystal structure is characterized by the presence of a substituent R 1 , R 2 , R 3 , and R 4 The molar ratio of each monomer unit when compound I is a copolymer (for example, the ratio m / (n+m) in copolymer II), the method for producing compound I, and other factors can affect the molecular weight of compound I.

[0051] The peaks in the second region are derived from the non-crystalline portion of Compound I (amorphous component).

[0052] Figures 3 and 4 are examples of wide-angle X-ray scattering profiles of compound I. Figure 3 is an example having two peaks in the first region, where the scattering vector q is around 3.5 and 7.0 (first region), and around 13.5 (second region). Figure 4 is an example having one peak in the first region, where the scattering vector q is around 7.0 (first region), and around 13.5 (second region).

[0053] [Configuration of film for electronic devices] First Embodiment The electronic device film 10 according to the first embodiment includes an adhesive layer 11 having adhesion to metal, and an insulating layer 12 covering the adhesive layer (FIG. 1). In the first embodiment, the main material is an insulating material, and examples of the material include polyimide, modified polyimide, liquid crystal polymer, and polyphenylene ether resin (PPE). Compound I is dispersed in the main material in the insulating layer 12. More specifically, compound I is compatible with the main material, and there is no clear boundary between compound I and the main material in the insulating layer 12.

[0054] The insulating material is not particularly limited as long as it is a material that is commonly used as an electrical insulating material. For example, the insulating material may have a volume resistivity of 1×10 13 It can be a material with a resistance of Ω·m or higher.

[0055] Second Embodiment The electronic device film 20 according to the second embodiment includes an adhesive layer 21 having adhesiveness to metals and an insulating layer 22 covering the adhesive layer (FIG. 2). In the second embodiment, the main material is a material having adhesiveness to metals, and examples of the material include epoxy resin, polyimide, modified polyimide, polyphenylene ether resin (PPE), etc. Compound I is dispersed in the main material in the adhesive layer 21.

[0056] More specifically, the adhesive layer 21 has a dispersion medium portion 23 made of a main material and particles 24 dispersed in the dispersion medium portion 23, and the particles 24 contain the compound I. In this case, the particle diameter of the particles can be, for example, 0.05 to 5 μm. Such particles can be manufactured, for example, by a melting method.

[0057] A material that has adhesive properties to metals may be, for example, a material that has a peel strength of 0.1 N / mm or more, measured by pressing a sample piece at 180°C and 3 MPa for 45 minutes using a cold-hot press machine, and peeling it at an angle of 180° and a tensile speed of 50 mm / min. In particular, it is preferable that the material has adhesive properties to copper, polyimide, etc.

[0058] (Modification) The above two embodiments are merely examples of the combination of the layer in which compound I and the main material are present and the dispersion form of compound I. Therefore, a configuration in which compound I is dispersed in the main material in the form of particles in the insulating layer, and a configuration in which compound I is compatible with the main material in the adhesive layer may also be adopted.

[0059] [Other components constituting films for electronic devices] The film for electronic devices according to the present embodiment may contain other components than the main material and compound I. The content of each component is not particularly limited, but the content of compound I is preferably 40% or more by weight, more preferably 50% or more by weight. The content of compound I is preferably 95% or less by weight, more preferably 90% or less by weight.

[0060] The electronic device film according to the present embodiment preferably contains a filler having a relative dielectric constant of 10 or less. In this case, the content of the filler is preferably 50% or less by weight. Examples of such a filler include, but are not limited to, low-dielectric silica and alumina.

[0061] The film for electronic devices according to this embodiment may contain known additives. Examples of such additives include, but are not limited to, plasticizers, antioxidants, flame retardants, stabilizers, ultraviolet absorbers, antistatic agents, lubricants, water repellents, oil repellents, and the like.

[0062] 〔Physical properties of the film for electronic devices〕 The film for electronic devices according to this embodiment preferably has a coefficient of linear expansion, specified as the slope at 50 to 100 °C in thermomechanical analysis under the conditions of a tensile load of 10 mN, a temperature range of 25 to 250 °C, and a heating rate of 5 °C / min, of 40 ppm or less. When the coefficient of linear expansion of the film for electronic devices is 30 ppm or less, it can be suitably used for applications where it is bonded to a copper foil (for example, as a substrate material and a coating material for printed circuit boards). More preferably, the coefficient of linear expansion of the film for electronic devices is 25 ppm or less. The lower limit of the coefficient of linear expansion is not particularly limited, but it can be, for example, 10 ppm or more. Thermomechanical analysis can be carried out using, for example, TMA7100 (manufactured by Hitachi High-Tech Science Corporation).

[0063] The film for electronic devices according to this embodiment preferably has a relative permittivity measured at a frequency of 10 GHz in accordance with JIS C 2565-1992 of 3.0 or less. When the relative permittivity of the film for electronic devices is 3.0 or less, it can be particularly suitably used for electronic devices for high-speed communication. More preferably, the relative permittivity of the film for electronic devices is 2.5 or less. Since Compound I has a lower relative permittivity compared to substances conventionally used in the art, it is easy to achieve a relative permittivity suitable for electronic device films.

[0064] The film for electronic devices according to the present embodiment preferably has a dielectric loss tangent of 0.003 or less, measured at a frequency of 10 GHz according to JIS C 2565-1992. If the film for electronic devices has a dielectric loss tangent of 0.003 or less, it can be particularly suitably used in electronic devices for high-speed communication. The film for electronic devices more preferably has a dielectric loss tangent of 0.002 or less. Compound I has a lower dielectric loss tangent than substances conventionally used in this field, and therefore it is easy to realize a dielectric loss tangent suitable for electronic device films.

[0065] The electronic device film according to the present embodiment preferably has a Young's modulus of 0.5 GPa or more as measured according to JIS K 7127:1999. When the Young's modulus of the electronic device film is 0.5 GPa or more, the electronic device film has high bending resistance, and is particularly suitable for use in printed circuit boards. The Young's modulus of the electronic device film is more preferably 1.0 GPa or more. The upper limit of the Young's modulus of the electronic device film is not particularly limited, but may be, for example, 10 GPa or less.

[0066] The film for electronic devices according to the present embodiment preferably has a breaking elongation of 3% or more as measured according to JIS K 7127:1999. When the breaking elongation of the film for electronic devices is 3% or more, the film for electronic devices has high bending resistance and is particularly suitable for use in printed circuit boards. The breaking elongation of the film for electronic devices is more preferably 5% or more. The upper limit of the breaking elongation of the film for electronic devices is not particularly limited, but may be, for example, 50% or less.

[0067] [Method of manufacturing a film for electronic devices] The film for electronic devices according to the present embodiment can be produced, for example, by a method including a dispersing step of dispersing compound I in a main material to obtain a precursor, and a film-forming step of forming a film from the precursor obtained in the dispersing step.

[0068] (1) Dispersion process In this embodiment, compound I is soluble in organic solvents such as toluene, decane, cyclohexane, cyclohexanone, etc., or is easily dispersed uniformly in these solvents. Therefore, the dispersion process can be carried out in the following order (first procedure example): first, a step of dissolving (or dispersing) compound I in an organic solvent is carried out, and second, a step of liquid-liquid mixing a solution containing compound I with a solution containing a main material (varnish) is carried out.

[0069] In addition, when a film for electronic devices (for example, film for electronic devices 20) in which compound I is dispersed in the main material in the form of particles is to be obtained, the dispersion process may be carried out in the following order (second procedure example): first, a step of producing particles of compound I is carried out, and second, a step of mixing the particles with a solution (varnish) containing the main material is carried out. The particles of compound I may be produced, for example, by a melting method as described above. A step of dispersing the particles in an organic solvent may also be provided.

[0070] Alternatively, the dispersion step may be carried out by mixing compound I and the main material by dry mixing (third procedure example).

[0071] (2) Film making process The method for carrying out the film-forming step is not particularly limited, and may be, for example, a casting method, a melt extrusion method, etc. When the casting method is adopted, it is preferable that a precursor in which the compound I and the main material are dissolved or dispersed in a liquid is obtained in the dispersion step, and for example, the above-mentioned first or second procedure example may be adopted.

[0072] When the melt extrusion method is adopted, it is preferable to obtain a solid mixture of compound I and the main material as a precursor, for example, the above-mentioned third procedure example can be adopted. Also, the mixing of compound I and the main material can be carried out as a single melt extrusion process without providing a dispersion step.

[0073] When the film for electronic devices according to the present embodiment contains other components than the main material and compound I, such other components may be mixed in the above-mentioned dispersion step or film formation step.

[0074] [Use of films for electronic devices] The film for electronic devices according to this embodiment can be used, for example, in a printed circuit board 1 including the film for electronic devices. Fig. 5 shows a schematic cross-sectional view illustrating the structure of the printed circuit board 1. The printed circuit board 1 has a substrate material 2, a copper foil 3, and a covering material 4, and the covering material 4 is composed of the film for electronic devices according to this embodiment. The substrate material 2 is composed of a material known as a material for printed circuit boards, and a detailed description thereof will be omitted.

[0075] When manufacturing the printed circuit board 1, the substrate material 2, copper foil 3, and covering material 4 (film for electronic devices) are stacked in this order and then heat-pressed. This causes the substrate material 2, copper foil 3, and covering material 4 to be thermally fused together. At this time, the adhesive layer (adhesive layer 11 or adhesive layer 21) of the film for electronic devices is in contact with the copper foil 3, so that the adhesive strength between the copper foil 3 and covering material 4 tends to be high. In this way, since the adhesive layer is provided, it is possible to change the conditions of the process for adhering the copper foil 3 and covering material 4 to be milder than when no adhesive layer is provided, and for example the processing temperature can be lowered.

[0076] [Functions and Effects of Film for Electronic Devices] The film for electronic devices according to the present embodiment exhibits physical properties (mechanical properties, heat resistance, adhesiveness, insulating properties, etc.) attributable to the main material, as well as improved electrical properties (dielectric constant and dielectric loss tangent lower than those of the main material). The improved electrical properties are attributable to the low dielectric constant and dielectric loss tangent of compound I.

[0077] In addition, Compound I has physical properties (glass transition point, linear expansion coefficient, etc.) at a level that allows it to be used alone as a material for films for electronic devices. Therefore, the addition of Compound I is unlikely to impair the physical properties of the main material that are favorable for films for electronic devices.

[0078] From the above, according to the present embodiment, it is possible to effectively improve only the electrical properties without making a major change to the design of an existing film for electronic devices that is constructed using a specific main material. Conventionally, it has been difficult to achieve both electrical properties and adhesiveness in an adhesive layer, but according to the present embodiment, it is possible to improve the electrical properties of the adhesive layer. In addition, the insulating layer is the main part of a film for electronic devices, and a change in the design of the insulating layer can have a significant effect on the performance of the film for electronic devices. However, according to the present embodiment, it is possible to improve the electrical properties of the insulating layer without changing the basic design of an existing film for electronic devices, or with a minimum change.

[0079] Other embodiments Finally, other embodiments of the film for electronic devices and the printed circuit board according to the present invention will be described below. Note that the configurations disclosed in the following embodiments can be combined with the configurations disclosed in other embodiments as long as no contradiction occurs.

[0080] In the above embodiment, an example of a film for electronic devices having an insulating layer and an adhesive layer has been described. However, the film for electronic devices according to the present invention may be composed of a single layer or may have three or more layers. For example, it is also possible to form the film for electronic devices according to the present invention, which is mainly made of an adhesive resin, on a metal foil, and then adhere a film made of an insulating material onto the film for electronic devices.

[0081] In the above embodiment, an example has been described in which the film for electronic devices according to the present embodiment is used for the printed circuit board 1. However, the application of the film for electronic devices according to the present invention is not limited to the printed circuit board, and may be, for example, a peripheral member for electronic devices such as a coverlay film or a bonding sheet.

[0082] Regarding other configurations, it should be understood that the embodiments disclosed in this specification are illustrative in all respects and that the scope of the present invention is not limited thereto. A person skilled in the art would easily understand that appropriate modifications are possible without departing from the spirit of the present invention. Therefore, other embodiments modified without departing from the spirit of the present invention are naturally included in the scope of the present invention. EXAMPLES

[0083] The present invention will be further described below with reference to examples, but the present invention is not limited to the following examples.

[0084] [Synthesis Example of Compound I] Compounds having the compositions shown below were synthesized as examples of the synthesis of compound I. The synthesis method of each compound was the same as that described above in the section "Method for producing compound I," except that the monomer unit of each compound was used.

[0085] (Compound Ia) As the compound Ia, an unsubstituted norbornene unit (in the formula (1), R 1 , R 2 , R 3 , and R 4 Compound I was synthesized in an embodiment containing only monomer units in which each of the monomer units is a hydrogen atom. The weight average molecular weight was 1,600. [ka]

[0086] (Compound Ib) Compound Ib is a compound having 30 mol % of unsubstituted norbornene units and vinylnorbornene units (in formula (1), R 1 is a vinyl group, and R 2 , R 3 , and R 4 Compound I was synthesized in an embodiment containing 70 mol % of a monomer unit in which R 1 is a vinyl group, and R2 is a hydrogen atom, and m / (n+m) is 0.7. [ka]

[0087] (Compound Ic) Compound Ic is a compound having 50 mol % of unsubstituted norbornene units, 30 mol % of vinylnorbornene units, and phenylethylnorbornene units (in formula (1), R 1 is a phenylethyl group, and R 2 , R 3 , and R 4 Compound I having an embodiment containing 20% ​​of (monomer units in which each of the monomer units is a hydrogen atom) was synthesized. The weight average molecular weight was 4,900. [ka]

[0088] (Compound Id) Compound Id was prepared by mixing 50 mol % of unsubstituted norbornene units and hexylnorbornene units (R 1 is a hexyl group, and R 2 , R 3 , and R 4 Compound I was synthesized having a weight average molecular weight of 50,000. Compound Id is a monomer unit represented by the formula (2) in which R 1 is a hexyl group, and R 2 is a hydrogen atom, and m / (n+m) is 0.5. [ka]

[0089] [Example of film for electronic devices] According to the first procedure example in the above section "Production method of film for electronic device", films for electronic devices of Examples 1 to 4 and Comparative Examples 1 to 4 were produced. Toluene was used as a solvent for dissolving compound I (compounds Ia to Id). Polyphenylene ether resin (PPE) or polyimide was used as varnish. The materials used as raw materials in each example are as shown in Table 1. The mixing ratio of varnish and compound I in each example is as shown in Tables 2 and 3 below.

[0090] Table 1: Materials used in the examples and comparative examples [Table 1]

[0091] When preparing the film for electronic devices in each example, the mixed solution after the dispersion process was visually evaluated for the dispersion state of Compound I (except for Comparative Examples 1 and 3 in which Compound I was not added). Tables 2 and 3 shown later show the evaluation results of the dispersion state according to the following three levels A to C. A: No gelation was observed and the dispersion was in a good state. B: Slight gelation is observed, but coating is possible. C: Gelation has occurred and coating is not possible.

[0092] The dielectric constant and dielectric loss tangent of each of the films for electronic devices obtained in the examples were measured according to the method described in the section "Physical properties of films for electronic devices." The compositions and evaluation results of each example are shown in Tables 2 and 3.

[0093] Table 2: Composition and evaluation results of films for electronic devices (1) [Table 2]

[0094] Table 3: Composition and evaluation results of films for electronic devices (2) [Table 3]

[0095] In all of Examples 1 to 4, when the varnish and compound I were mixed, a mixed solution was obtained that was homogeneous enough to be able to be cast into a film (Tables 2 and 3). On the other hand, in Comparative Examples 2 and 4, the dispersion of compound I in the varnish was non-uniform, and film formation by the cast method could not be performed. In Comparative Examples 2 and 4, the molecular weight of compound I was larger than in Examples 1 to 4, so it is considered that compound I (compound Id) was difficult to disperse. Note that, since no film was obtained in Comparative Examples 2 and 4, the relative dielectric constant and dielectric loss tangent could not be measured.

[0096] Furthermore, among the examples in which a polyphenylene ether resin was used as the varnish, Examples 1 to 3 containing compound I had lower dielectric constants and dielectric loss tangents than Comparative Example 1 not containing compound I. Similarly, among the examples in which a polyimide was used as the varnish, Example 4 containing compound I had lower dielectric constants and dielectric loss tangents than Comparative Example 3 not containing compound I. That is, it was shown that the addition of compound I reduced the dielectric constant and dielectric loss tangent in both the cases in which a polyphenylene ether resin was used as the varnish and the case in which a polyimide was used. [Industrial Applicability]

[0097] The present invention can be used in electronic devices, such as printed circuit boards. [Explanation of symbols]

[0098] 10: Film for electronic devices (first embodiment) 11: Adhesive layer 12: Insulating layer 20: Film for electronic devices (second embodiment) 21: Adhesive layer 22: Insulating layer 23:Dispersion medium part 24: Particle 1: Printed circuit board 2: Substrate material 3: Copper foil 4: Coating material

Claims

1. At least one type of main material formed into a film shape; a compound dispersed in the base material; The compound is a homopolymer of a monomer unit represented by formula (1) or a copolymer of a plurality of types of the monomer units, The compound has a weight average molecular weight of 1,000 or more and 20,000 or less. 【Chemistry 1】 During the ceremony, R １ and R ２ are each independently selected from the group consisting of a hydrogen atom and a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, or are joined together to form an alkylidene group, R ３ and R ４ are each independently selected from the group consisting of a hydrogen atom and a substituted or unsubstituted hydrocarbon group having 1 to 30 carbon atoms, or together form an alkylidene group.

2. The compound has the formula (1) R １ , R ２ , R ３ , and R ４ The film for electronic devices according to claim 1 , comprising a monomer unit in which all of the radicals are hydrogen atoms.

3. 3. The film for electronic devices according to claim 1, wherein the compound is a copolymer.

4. having particles dispersed in the base material; 4. The film for electronic devices according to claim 1, wherein the particles contain the compound.

5. An adhesive layer having adhesion to metal, and an insulating layer at least partially covering the adhesive layer, the main material is an insulating material, 5. The film for electronic devices according to claim 1, wherein the compound is dispersed in the main material in the insulating layer.

6. An adhesive layer having adhesion to metal, and an insulating layer at least partially covering the adhesive layer, the main material is a material having adhesion to metal, 5. The film for electronic devices according to claim 1, wherein the compound is dispersed in the main material in the adhesive layer.

7. A printed circuit board comprising the film for electronic devices according to any one of claims 1 to 6.

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