Composite material, application product thereof, and composite material manufacturing method

Abstract

A composite material according to one aspect of the present disclosure includes a base material and polydopamine. Where a straight line connecting the measurement point at 3070 cm-1 and the measurement point at 3700 cm-1 in the infrared absorption spectrum of the composite material obtained by Fourier transform infrared spectroscopy is defined as a baseline, the following condition is satisfied: 0.66 ≤ HB / HA ≤ 1.1. Here, HA indicates the vertical distance from the measurement point at 3380 cm-1 of the infrared absorption spectrum to the baseline, and HB indicates the vertical distance from the measurement point at 3630 cm-1 of the infrared absorption spectrum to the baseline.

Description

Composite materials, their application products, and manufacturing methods for composite materials

[0001] The present disclosure relates to composite materials, their applications, and methods for manufacturing composite materials.

[0002] In recent years, in the electronics field, the level of performance required of electronic devices has been increasing in preparation for the expansion of fifth-generation mobile communication systems (5G). For example, 5G uses higher frequency bands to achieve faster communication speeds than previous generations. This means that electronic devices require wiring boards that can handle high frequencies.

[0003] Transmission loss in the transmission path of a wiring board depends on frequency, increasing as the signal frequency increases. Transmission loss depends on the relative dielectric constant and dielectric dissipation factor. Therefore, to reduce transmission loss of high-frequency signals, the substrate material that makes up the insulating layer of a wiring board must have a low relative dielectric constant and dielectric dissipation factor. Particularly in the high-frequency band, the dielectric dissipation factor is highly dependent on the orientation polarization of the organic molecules contained in the substrate material. Therefore, it is necessary to reduce the polar groups, such as hydroxyl groups and amino groups, contained in the substrate material.

[0004] Furthermore, high-capacity communications such as 5G use high-frequency bands, resulting in short radio wave transmission distances. This necessitates increased output power from electronic devices. Furthermore, with the realization of high integration and miniaturization, circuit packaging density also increases. Meeting these needs increases the amount of heat generated per unit area of ​​the wiring board. Therefore, wiring boards are required to have high heat dissipation properties. To improve the heat dissipation properties of wiring boards, the substrate material that constitutes the insulating layer of the wiring board is enriched with a filler (filling agent) with excellent thermal conductivity to increase the thermal conductivity of the wiring board.

[0005] Japanese Patent Application Laid-Open No. 2018-043899

[0006] Haeshin Lee, Shara M. Dellatore, William M. Miller, Phillip B. Messersmith, Science, 2007, vol. 318, 426-430Heng Shen, Jing Guo, Hao Wang, Ning Zhao, Jian Xu, ACS Appl. Mater. Interfaces, 2015, 7, 5701-5708Katerina G. Malollari, Peyman Delparastan, Caroline Sobek, Shraddha J. Vachhani, Tanner D. Fink, R. Helen Zha, Phillip B. Messersmith, Mechanical Enhancement of Bioinspired Polydopamine Nanocoatings, ACS Appl. Mater. Interfaces, 2019, 11, 43599-43607

[0007] In the prior art, it is desirable to reduce the dielectric loss tangent of the substrate.

[0008] The composite material of the present disclosure is a composite material comprising: a substrate; and polydopamine, wherein the composite material has a peak at 3070 cm in an infrared absorption spectrum obtained by Fourier transform infrared spectroscopy. -1 Measurement points at 3700 cm -1 When the straight line connecting the measurement points at H is defined as the baseline, 0.66≦H B / H A ≦1.1, and H A is the 3380 cm of the infrared absorption spectrum -1 indicates the vertical distance from the measurement point at B is the 3630 cm of the infrared absorption spectrum -1 The vertical distance from the measurement point to the baseline is shown.

[0009] According to the present disclosure, the dielectric loss tangent of the substrate can be reduced.

[0010] FIG. 1 is a diagram showing a schematic configuration of a composite material according to Embodiment 1. FIG. 2 is an example of an infrared absorption spectrum of the composite material according to Embodiment 1. FIG. 3 is an enlarged view of a key portion of the infrared absorption spectrum of FIG. 2. FIG. 4 is a flowchart showing an example of a method for producing a composite material according to Embodiment 1. FIG. 5 is a diagram showing a schematic configuration of a resin composition according to Embodiment 4. FIG. 6 is a cross-sectional view of a resin-coated film according to Embodiment 6. FIG. 7 is a cross-sectional view of a resin-coated metal foil according to Embodiment 7. FIG. 8 is a cross-sectional view of a metal-clad laminate according to Embodiment 8. FIG. 9 is a cross-sectional view of a wiring board according to Embodiment 9. FIG. 10 is an infrared absorption spectrum of Examples 1, 2, 7, 8, and Comparative Example 1. FIG. 11A is an enlarged view of a key portion of the infrared absorption spectrum of Example 1. FIG. 11B is an enlarged view of a key portion of the infrared absorption spectrum of Example 2. FIG. 11C is an enlarged view of a key portion of the infrared absorption spectrum of Example 7. FIG. 11D is an enlarged view of a key portion of the infrared absorption spectrum of Example 8. FIG. 12 is an XPS N1s spectrum of Example 2.

[0011] (Findings that form the basis of the present disclosure) Increasing the filler content in a resin composition to improve the heat dissipation of a wiring board impairs mechanical properties such as flexibility, and the insulating layer tends to become brittle. This is thought to be due to the aggregation of the filler in the resin composition. Chemical modification of the filler surface is effective in improving dispersibility while suppressing the aggregation of the filler.

[0012] Boron nitride is a material with high thermal conductivity, excellent heat dissipation, and excellent electrical insulation. Therefore, boron nitride has recently attracted attention as a filler for the insulating layer of wiring boards (see, for example, Patent Document 1). However, the amount of functional groups present on the surface of boron nitride particles is small, and most of the surface is inactive. Therefore, it has been difficult to improve the dispersibility of boron nitride particles in resin compositions by directly treating the surface of the particles using methods such as silane coupling.

[0013] Here, dopamine-containing proteins secreted from the byssus glands of the blue mussel, a type of bivalve, exhibit stable adhesive strength even in seawater and are known as natural adhesives. According to Non-Patent Document 1, when a substrate is immersed in an aqueous dopamine solution, a thin film of polydopamine is formed on the surface of the substrate due to the autoxidative polymerization of dopamine. Non-Patent Document 2 describes that by utilizing this property to coat boron nitride with polydopamine, the dispersibility of boron nitride as a filler is improved. Furthermore, Non-Patent Document 3 describes heat-treating polydopamine at 130°C.

[0014] However, polydopamine has many hydroxyl groups, making it hydrophilic, meaning that it easily absorbs moisture from the atmosphere. Therefore, when polydopamine is attached to boron nitride and used as a filler, there is a concern that the dielectric loss tangent may deteriorate.

[0015] The present inventors have conducted extensive research into reducing the dielectric loss tangent of a substrate, and as a result have come up with the composite material of the present disclosure.

[0016] (Summary of one aspect of the present disclosure) A composite material according to a first aspect of the present disclosure is a composite material including: a substrate; and polydopamine, wherein an infrared absorption spectrum of the composite material obtained by Fourier transform infrared spectroscopy has a peak at 3070 cm -1 Measurement points at 3700 cm -1 When the straight line connecting the measurement points at H is defined as the baseline, 0.66≦H B / H A ≦1.1, where H A is the 3380 cm of the infrared absorption spectrum -1 indicates the vertical distance from the measurement point at B is the 3630 cm of the infrared absorption spectrum -1 The vertical distance from the measurement point to the baseline is shown.

[0017] According to the above configuration, the dielectric loss tangent of the composite material can be reduced.

[0018] In the second aspect of the present disclosure, for example, in the composite material according to the first aspect, 0.70≦H B / H A ≦0.90. According to the above configuration, the dielectric loss tangent of the composite material can be further reduced.

[0019] In a third aspect of the present disclosure, for example, in the composite material according to the first or second aspect, in an N1s spectrum of the composite material obtained by X-ray photoelectron spectroscopy, the ratio of the area of ​​the peak attributable to the nitrogen atom of the primary amino group to the area of ​​the entire N1s spectrum may be 3.0% or more and 7.0% or less. With this configuration, the dielectric loss tangent of the composite material can be further reduced.

[0020] In a fourth aspect of the present disclosure, for example, in the composite material according to any one of the first to third aspects, the substrate may contain at least one selected from the group consisting of boron nitride, aluminum nitride, silicon nitride, aluminum oxide, magnesium oxide, and silica. The composite material of the present disclosure is particularly useful when the substrate contains at least one selected from the above group.

[0021] In a fifth aspect of the present disclosure, for example, in the composite material according to the fourth aspect, the substrate may contain boron nitride. The composite material of the present disclosure is particularly useful when the substrate contains boron nitride.

[0022] A filler according to a sixth aspect of the present disclosure includes the composite material according to any one of the first to fifth aspects. According to the above configuration, the dielectric loss tangent of the filler can be reduced.

[0023] A resin composition according to a seventh aspect of the present disclosure includes the filler according to the sixth aspect. According to the seventh aspect, it is possible to provide a filler that exhibits a low dielectric loss tangent and excellent heat resistance.

[0024] A prepreg according to an eighth aspect of the present disclosure includes the resin composition of the seventh aspect or a semi-cured product of the resin composition.

[0025] A resin-coated film according to a ninth aspect of the present disclosure comprises: a resin layer containing the resin composition of the seventh aspect or a semi-cured product of the resin composition; and a support film.

[0026] A resin-coated metal foil according to a tenth aspect of the present disclosure comprises: a resin layer containing the resin composition of the seventh aspect or a semi-cured product of the resin composition; and a metal foil.

[0027] A metal-clad laminate according to an eleventh aspect of the present disclosure comprises: an insulating layer containing a cured product of the resin composition according to the seventh aspect or a cured product of the prepreg according to the eighth aspect; and a metal foil.

[0028] A wiring board according to a twelfth aspect of the present disclosure includes: an insulating layer including a cured product of the resin composition of the seventh aspect or a cured product of the prepreg of the eighth aspect; and wiring.

[0029] According to the eighth to twelfth aspects, various application products suitable for high frequencies can be provided.

[0030] A method for producing a composite material according to a thirteenth aspect of the present disclosure includes: attaching polydopamine to a surface of a substrate; and heating the substrate and the polydopamine attached to the surface.

[0031] According to the above-described configuration, a composite material with a reduced dielectric loss tangent can be produced.

[0032] In a fourteenth aspect of the present disclosure, for example, in the method for producing a composite material according to the thirteenth aspect, the heating may involve heating the substrate and the polydopamine at a temperature of 100° C. or higher and 400° C. or lower. This configuration further reduces the dielectric loss tangent of the composite material.

[0033] In a fifteenth aspect of the present disclosure, for example, in the method for producing a composite material according to the thirteenth aspect, the heating may involve heating the substrate and the polydopamine at a temperature of 200° C. or higher and 300° C. or lower. This configuration further reduces the dielectric loss tangent of the composite material.

[0034] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0035] First Embodiment Hereinafter, a first embodiment will be described with reference to FIGS. 1 to 4. FIG.

[0036] 1 is a diagram showing a schematic configuration of a composite material 10 according to embodiment 1. The composite material 10 includes a substrate 1 and polydopamine 2.

[0037] Polydopamine 2 may be attached to the surface of the substrate 1. Specifically, the surface of the substrate 1 may be chemically modified with polydopamine 2, thereby causing polydopamine 2 to be attached to the surface of the substrate 1. Polydopamine 2 may cover at least a portion of the surface of the substrate 1. Polydopamine 2 may cover the entire surface of the substrate 1, or may cover only a portion of the surface of the substrate 1.

[0038] In the infrared absorption spectrum of the composite material 10, -1 Measurement point P at 3070 and 3700 cm -1 Measurement point P at 3700 The straight line connecting these points is defined as the baseline L. The composite material 10 has a resistance of 0.66≦H B / H A ≦1.1, where H A is the 3380 cm in the infrared absorption spectrum. -1 indicates the vertical distance from the measurement point P1 to the baseline L at H B is the 3630 cm in the infrared absorption spectrum -1 The vertical distance from the measurement point P2 to the baseline L is shown. The infrared absorption spectrum is a spectrum obtained by the diffuse reflectance method of Fourier transform infrared spectroscopy (FT-IR).

[0039] FIG. 2 shows an example of the infrared absorption spectrum of the composite material 10. In each drawing of the present application, the infrared absorption spectrum is shown with the vertical axis representing transmittance (%). FIG. 2 shows an example in which boron nitride is used as the substrate 1. FIG. 3 is an enlarged view of a main portion of the infrared absorption spectrum of FIG. 2. As shown in FIG. 3, in the infrared absorption spectrum, a peak at 3070 cm -1 More than 3450cm -1 The following range is defined as the first absorption band B1, and 3580 cm -1 More than 3680cm -1The following range is defined as a second absorption band B2: The first absorption band B1 and the second absorption band B2 each have a minimum value of transmittance within their respective ranges.

[0040] The transmittance in the vicinity of the measurement point P1 of the first absorption band B1 depends on the amount of hydroxyl groups forming hydrogen bonds contained in the coating film of polydopamine 2. For example, as the amount of hydroxyl groups forming hydrogen bonds contained in the coating film of polydopamine 2 decreases, the transmittance in the vicinity of the measurement point P1 of the first absorption band B1 increases. A The value of reflects the amount of hydroxyl groups forming hydrogen bonds contained in the coating film of polydopamine 2. The transmittance in the vicinity of the measurement point P2 of the second absorption band B2 depends on the amount of free hydroxyl groups contained in the coating film of polydopamine 2. In other words, the transmittance in the vicinity of the measurement point P2 of the second absorption band B2 depends on the amount of free hydroxyl groups contained in the coating film of polydopamine 2. For example, as the amount of free hydroxyl groups contained in the coating film of polydopamine 2 decreases, the transmittance in the vicinity of the measurement point P2 of the second absorption band B2 increases. Therefore, H B The value of reflects the amount of free hydroxyl groups contained in the coating film of polydopamine 2. B / H A is a parameter that specifies the relationship between the amount of hydroxyl groups forming hydrogen bonds contained in the coating film of polydopamine 2 and the amount of free hydroxyl groups contained in the coating film of polydopamine 2 by the ratio of the vertical distance from the measurement point P2 of the second absorption band B2 to the vertical distance from the measurement point P1 of the first absorption band B1 to the vertical distance from the vertical distance from the vertical distance from the vertical distance from the vertical distance from the vertical distance from the vertical distance from the measurement point P2 of the second absorption band B2 to the vertical distance from the vertical distance from the vertical distance from the vertical distance from the vertical distance from the vertical distance from the measurement point P1 of the first absorption band B1 to the vertical distance from ... B / H A is 0.815.

[0041] The inventors have determined that the composite material 10 has a hardness of 0.66≦H B / H A It was found that when the condition of H≦1.1 is satisfied, a reduction in the dielectric loss tangent is realized. In the heat treatment described below, when the heat treatment temperature is increased, the number of free hydroxyl groups contained in the coating film of polydopamine 2 decreases, and thus the dielectric loss tangent decreases. B / H AThe larger the H, the lower the dielectric loss tangent. However, if the heat treatment temperature is too high, the dielectric loss tangent tends to increase. B / H A When the heat treatment temperature is too high, the dielectric loss tangent tends to increase. This is presumably because the cyclic structure (indoline skeleton and / or indole skeleton) of polydopamine 2 is degraded due to the excessively high heat treatment temperature.

[0042] The composite material 10 has a resistance of 0.70≦H B / H A ≦0.90. According to the above configuration, the dielectric loss tangent of the composite material 10 is further reduced.

[0043] In the N1s spectrum of the composite material 10, the ratio R of the area of ​​the peak derived from the nitrogen atom of the primary amino group to the area of ​​the entire N1s spectrum may be 3.0% or more and 7.0% or less. The N1s spectrum is a spectrum obtained by X-ray photoelectron spectroscopy (XPS).

[0044] XPS is a method for analyzing the constituent elements and their electronic states of a sample by irradiating the surface of the sample with X-rays and measuring the energy of the resulting photoelectrons. XPS can measure the state of chemical bonding of nitrogen in a composite material 10. Specifically, in the N1s spectrum measured by XPS, a peak called N1s is obtained due to photoelectrons originating from nitrogen atoms present on the surface of the sample. In the N1s spectrum, the vertical axis represents the intensity of the spectrum (arbitrary units), and the horizontal axis represents the binding energy (eV). The N1s peak is a composite of various peaks that depend on the bonding state of the nitrogen atoms present on the surface of the sample. The positions of these various peaks are determined by the state of chemical bonding of the nitrogen atoms. The peak originating from the nitrogen atoms of the primary amino group is defined as peak P1. For example, in the N1s spectrum, peak P1 appears near 402 eV.

[0045] The ratio R1 can be determined by the following method. First, the obtained N1s spectrum is separated into peak P1 and other peaks. The area of ​​each peak is calculated. The ratio R1 can be determined by calculating the ratio of the area of ​​peak P1 to the sum of these areas. Peak P1 can be separated from other peaks by the following method. The N1s spectrum obtained by XPS appears in the binding energy range of the N1s electron of the nitrogen atom (approximately 396 to 404 eV). The composite material 10 is considered to contain three components: =N-R, R2-NH, and R-NH2. However, since the peaks of these components overlap, the peaks of each component can be separated by approximating them with a Gaussian-Lorentzian composite function and performing fitting using the peak intensity, peak position, and full width at half maximum as parameters.

[0046] As described below (see formula (1) below), polydopamine 2 may have an indoline skeleton and / or an indole skeleton. However, polydopamine 2 may include polydopamines that are not completely cyclized. That is, polydopamine 2 may contain a mixture of primary amines and secondary amines. In composite material 10, the heat treatment described below causes primary amines to contribute to the cyclization and crosslinking of polydopamines, thereby stabilizing the polydopamine structure. Therefore, in composite material 10, the amount of primary amines decreases and the amount of secondary amines increases. Furthermore, primary amines react with hydroxyl groups contained in polydopamine to form imine bonds (C═N), thereby reducing the number of hydroxyl groups. Therefore, the dielectric loss tangent of composite material 10 is further reduced.

[0047] In this embodiment, the ratio R1 may satisfy 3.5%≦R1≦6.5%, or 3.9%≦R1≦5.8%, in which case the dielectric loss tangent is further reduced.

[0048] [Substrate] The substrate 1 may contain at least one selected from the group consisting of boron nitride, aluminum nitride, silicon nitride, aluminum oxide, magnesium oxide, and silica. The composite material 10 is particularly useful when the substrate 1 contains at least one selected from the above group.

[0049] The substrate 1 may contain boron nitride. The composite material 10 is particularly useful when the substrate 1 contains boron nitride. Boron nitride has excellent thermal conductivity and is therefore used, for example, as a filler. The substrate 1 may be boron nitride.

[0050] Examples of boron nitride that can be used include hexagonal boron nitride (h-BN) having a graphite-type layered structure, diamond-type cubic boron nitride (c-BN), and amorphous boron nitride (a-BN). h-BN is particularly useful because it can be synthesized relatively easily and has excellent thermal conductivity, electrical insulation, chemical stability, and heat resistance. Boron nitride particles can be used as the boron nitride. Boron nitride particles are usually white. The shape of the boron nitride particles is not particularly limited. The shape of the boron nitride particles may be, for example, scale-like, spherical, oval-spherical, rod-like, or the like.

[0051] The average particle size of the boron nitride particles is not particularly limited. The average particle size of the boron nitride particles may be, for example, 0.05 μm or more and 100 μm or less, or 0.1 μm or more and 50 μm or less. In the present disclosure, the average particle size of the boron nitride particles refers to the median diameter. The median diameter refers to the particle size (d50) when the cumulative volume in the volume-based particle size distribution is equal to 50%. The volume-based particle size distribution is measured, for example, using a laser diffraction measurement device.

[0052] [Polydopamine] Polydopamine 2 is a dopamine polymer and may have, for example, one or both of the two repeating units represented by the following formula (1): In the following formula (1), the indoline skeleton may be an indole skeleton.

[0053]

[0054] In the above formula (1), n ​​is an integer of 1 or more. In the above formula (1), n ​​may be an integer of 2 or more.

[0055] The polydopamine 2 may be in the form of a thin film on the surface of the substrate 1. The thickness of the thin film of polydopamine 2 is, for example, 1 nm to 300 nm. The thin film of polydopamine 2 covers at least a portion of the surface of the substrate 1. The thin film of polydopamine 2 may cover the entire surface of the substrate 1, as exemplified in FIG. 1 .

[0056] The adhesion of polydopamine 2 to the substrate 1 can be confirmed by the fact that the surface of the substrate 1 is colored blackish brown.

[0057] In this specification, even if some of the functional groups derived from dopamine in the polymer are changed by heat treatment, the polymer is treated as a "polydopamine." One example of the change in functional groups is the loss of hydroxyl groups that occurs when polydopamine is heat treated.

[0058] [Method for Manufacturing Composite Material] Next, a method for manufacturing the composite material 10 described above will be described.

[0059] 4 is a flowchart showing an example of a method for producing the composite material 10. The method for producing the composite material 10 includes adhering polydopamine 2 to the surface of the substrate 1 (step S1) and heating the substrate 1 and the polydopamine 2 adhered to the surface of the substrate 1 (step S2).

[0060] In step S1, polydopamine 2 is attached to the surface of the substrate 1 by utilizing the autoxidative polymerization of dopamine. Specifically, a dopamine solution is brought into contact with the substrate 1, and the dopamine is oxidatively polymerized, thereby attaching polydopamine 2 to the surface of the substrate 1 and forming a thin film of polydopamine 2.

[0061] A dopamine solution can be obtained by adding dopamine hydrochloride to a Tris-HCl solution whose pH has been adjusted to 8.5 and stirring the mixture. The concentration of the dopamine solution is not particularly limited and may be, for example, in the range of 0.01 mg / mL to 30 mg / mL. The pH of the dopamine solution may be in the range of 6 to 11, or may be in the range of 8 to 10. The pH of the dopamine solution can be adjusted by adding a Tris-HCl solution or the like. The temperature of the dopamine solution during oxidative polymerization is, for example, 10°C to 100°C. The polymerization time is, for example, 1 hour to 48 hours. The thickness of the polydopamine 2 thin film is, for example, 1 nm to 300 nm. The thickness of the polydopamine 2 thin film can be controlled by the polymerization time.

[0062] In step S2, the substrate 1 and the polydopamine 2 attached to the surface of the substrate 1 are heated, thereby obtaining a composite material 10.

[0063] The heating method is not particularly limited. Heating can be performed using a known heat treatment device such as a sintering device, an electric furnace, a hot plate, etc. Heating using a sintering device or an electric furnace is preferred because temperature control is easy.

[0064] In step S2, the substrate 1 may be heated so that the ambient temperature is in the range of 100°C or higher and 400°C or lower, or may be heated so that the ambient temperature is in the range of 200°C or higher and 300°C or lower. In step S2, the substrate 1 may be heated so that the ambient temperature is in the range of 220°C or higher and 260°C or lower. When the heating temperature is 100°C or higher, the hydroxyl groups and adsorbed water contained in the polydopamine 2 can be sufficiently reduced. When the heating temperature is 400°C or lower, alteration of the structure of the polydopamine 2 can be suppressed.

[0065] The heating time is, for example, 1 hour or more and 48 hours or less. The heating time may be 5 hours or more and 40 hours or less, or 10 hours or more and 30 hours or less. When the heating time is 5 hours or more, the hydroxyl groups and adsorbed water contained in polydopamine 2 can be sufficiently removed. When the heating time is 40 hours or less, a decrease in productivity and an increase in cost can be suppressed.

[0066] In the high frequency band, ranging from GHz to THz, the dielectric loss tangent is highly dependent on the orientation polarization of the organic molecules contained in the wiring board material. The hydroxyl groups of polydopamine 2 can increase the dielectric loss tangent. However, in composite material 10, the number of hydroxyl groups in polydopamine 2 is reduced by heat treatment, allowing the dielectric loss tangent of composite material 10 to be reduced.

[0067] Second Embodiment A heat dissipating gap filler according to this embodiment includes the composite material 10 according to the first embodiment.

[0068] In this disclosure, a thermal dissipation gap filler is a filler that is applied to electronic components such as substrate materials to fill air pockets or gaps, thereby dissipating heat from the electronic components. The thermal dissipation gap filler is a curing type thermal paste that hardens from a paste state into a sheet state. The thermal dissipation gap filler according to this embodiment can improve the heat resistance of the filler.

[0069] The heat dissipation gap filler according to this embodiment can be produced by, for example, mixing the composite material 10 according to the first embodiment with an epoxy resin or a silicone-based resin, or a non-silicone acrylic resin or a ceramic resin.

[0070] Third Embodiment A filler for thermal grease according to this embodiment includes the composite material 10 according to the first embodiment.

[0071] In this disclosure, the term "thermal grease filler" refers to a filler used in thermal grease. Thermal grease is a non-hardening thermal paste that is applied to electronic components such as circuit board materials to fill air pockets or gaps, thereby dissipating heat from the electronic components. The thermal grease filler according to this embodiment can improve the heat resistance of the filler.

[0072] The filler for thermal grease according to this embodiment can be produced, for example, by kneading the composite material 10 according to embodiment 1 with an epoxy resin or a silicone-based resin, or a non-silicone acrylic resin or a ceramic-based resin.

[0073] 5 is a diagram showing a schematic configuration of a resin composition 20 according to an embodiment 4. The resin composition 20 includes, for example, a filler 22 and a curable resin 24.

[0074] The filler 22 includes the composite material 10 described in the first embodiment. According to the present embodiment, a resin composition 20 can be provided that exhibits a low dielectric tangent and excellent heat resistance. As the filler 22, the composite material 10 alone may be used, or other filler materials such as silica particles may be used in combination with the composite material 10.

[0075] Examples of the curable resin 24 include epoxy resin, cyanate ester compound, maleimide compound, phenol resin, acrylic resin, polyamide resin, polyamideimide resin, thermosetting polyimide resin, polyphenylene ether resin, etc. As the curable resin 24, one or a combination of two or more selected from these can be used.

[0076] The resin composition 20 may contain other components, such as a curing agent, a flame retardant, an ultraviolet absorber, an antioxidant, a reaction initiator, a silane coupling agent, a fluorescent brightener, a photosensitizer, a dye, a pigment, a thickener, a lubricant, an antifoaming agent, a dispersant, a leveling agent, a gloss agent, an antistatic agent, a polymerization inhibitor, and an organic solvent. If necessary, one or a combination of two or more selected from these may be used.

[0077] (Embodiment 5) A prepreg according to embodiment 5 comprises the resin composition 20 of embodiment 4 or a semi-cured product thereof shown in Figure 5, and a fibrous base material. The fibrous base material is present in the matrix of the resin composition 20 or the semi-cured product. The prepreg is a composite material of the resin composition 20 and the fibrous base material. According to this embodiment, a prepreg suitable for high-frequency wiring boards can be provided.

[0078] In this embodiment, the semi-cured product refers to a material in a partially cured state to the extent that the resin composition 20 can be further cured. In other words, the semi-cured product is a material in a semi-cured state of the resin composition 20. For example, when the resin composition 20 is heated, its viscosity gradually decreases. As heating continues, curing begins, and the viscosity gradually increases. In such a case, the semi-cured state refers to the state of the resin composition 20 from the point when the viscosity starts to increase until the resin composition 20 is completely cured.

[0079] The fibrous substrate may be any known material used in various types of laminates for electrical insulating materials, such as glass cloth, aramid cloth, polyester cloth, glass nonwoven fabric, aramid nonwoven fabric, polyester nonwoven fabric, pulp paper, and linter paper.

[0080] The resin composition 20 is impregnated into the fibrous base material by a process such as immersion or coating. The fibrous base material impregnated with the resin composition 20 is heated under predetermined heating conditions to obtain the prepreg in the uncured or semi-cured state according to the present embodiment.

[0081] (Embodiment 6) Fig. 6 is a cross-sectional view of a resin-coated film 30 in embodiment 6. The resin-coated film 30 comprises a resin layer 32 containing the resin composition 20 or a semi-cured product thereof, and a support film 34. According to this embodiment, a resin-coated film 30 suitable for an insulating layer can be provided. The resin layer 32 is supported by the support film 34. In the example of Fig. 6, the support film 34 is disposed on the surface of the resin layer 32. However, another layer such as an adhesive layer may be provided between the resin layer 32 and the support film 34.

[0082] The resin layer 32 includes the resin composition 20 of the fourth embodiment shown in FIG. 5 or a semi-cured product thereof, and may or may not include a fibrous base material. The fibrous base material may be the same material as the fibrous base material of the prepreg. The resin layer 32 hardens and transforms into an insulating layer. An example of such an insulating layer is the insulating layer of a wiring board.

[0083] Any support film used for a resin-coated film can be used without limitation as the support film 34. Examples of the support film 34 include resin films such as polyester films and polyethylene terephthalate films.

[0084] Seventh Embodiment Fig. 7 is a cross-sectional view of a resin-coated metal foil 40 according to a seventh embodiment. The resin-coated metal foil 40 comprises a resin layer 42 containing the resin composition 20 or a semi-cured product thereof, and a metal foil 44. The resin layer 42 is supported by the metal foil 44. This embodiment can provide a resin-coated metal foil 40 suitable for electronic circuit components such as wiring boards. In the example of Fig. 7, the metal foil 44 is disposed on the surface of the resin layer 42. However, another layer, such as an adhesive layer, may be provided between the resin layer 42 and the metal foil 44.

[0085] The resin layer 42 contains the resin composition of the fourth embodiment shown in FIG. 5 or a semi-cured product thereof, and may or may not contain a fibrous base material. The fibrous base material may be the same material as the fibrous base material of the prepreg. The resin layer 42 hardens and transforms into an insulating layer. An example of such an insulating layer is the insulating layer of a wiring board.

[0086] There are no limitations on the metal foil 44. Metal foils with resins and metal foils used in metal-clad laminates can be used. Examples of metal foils include copper foil and aluminum foil.

[0087] Eighth Embodiment Fig. 8 is a cross-sectional view of a metal-clad laminate 50 according to an eighth embodiment. The metal-clad laminate 50 includes an insulating layer 52 and at least one metal foil 54. According to this embodiment, a metal-clad laminate 50 suitable for wiring boards can be provided. The insulating layer 52 includes a cured product of the resin composition 20 of the fourth embodiment shown in Fig. 5 or a cured product of the prepreg of the fifth embodiment. The metal foil 54 is disposed on the surface of the insulating layer 52. In this embodiment, a metal foil 54 is disposed on each of the front and back surfaces of the insulating layer 52.

[0088] The metal-clad laminate 50 is typically manufactured using the prepreg of the fifth embodiment. For example, 1 to 20 prepregs are stacked to form a laminate. Metal foil is placed on one or both sides of the prepreg laminate, and the laminate is heated and pressed to obtain the metal-clad laminate 50. Examples of the metal foil 54 include copper foil and aluminum foil.

[0089] The molding conditions for producing the metal-clad laminate 50 may be, for example, the molding conditions for producing laminates for electrical insulating materials and multilayer boards.

[0090] (Embodiment 9) Fig. 9 is a cross-sectional view of a wiring board 60 in embodiment 9. The wiring board 60 includes an insulating layer 62 and wiring 64. According to this embodiment, it is possible to provide a wiring board 60 suitable for high frequencies. The insulating layer 62 includes a cured product of the resin composition 20 of embodiment 4 shown in Fig. 5 or a cured product of the prepreg of embodiment 5. The wiring 64 is supported by the insulating layer 62. More specifically, the wiring 64 is disposed on the insulating layer 62. The wiring 64 can be formed by partially removing the metal foil.

[0091] 8 is patterned by a method such as etching to obtain a wiring board 60 having wiring 64 forming a circuit on the surface of an insulating layer 62. That is, the wiring board 60 is obtained by partially removing the metal foil 54 on the surface of the metal-clad laminate 50 so as to form a circuit.

[0092] A new laminate may be formed by laminating the prepreg of embodiment 5 on at least one surface of wiring board 60 and then applying heat and pressure. A multilayer wiring board can be obtained by patterning the metal foil on the surface of the obtained laminate to form wiring.

[0093] The present disclosure will be specifically described below with reference to examples. The examples are intended to illustrate the present disclosure and are not intended to limit the scope of the present disclosure.

[0094] Example 1 Boron nitride was used as the substrate. The boron nitride was h-BN (manufactured by Denka, product number: SGP, average particle size: 18 μm). A dopamine solution (concentration: 23 mg / mL) was obtained by adding dopamine hydrochloride to a Tris-HCl solution adjusted to pH 8.5 and stirring. 4.5 g of boron nitride was added to the obtained dopamine solution. The solution temperature was set to 80°C and stirred with a magnetic stirrer for 24 hours. A solid was then obtained by filtration. The obtained solid was washed with water and then dried. This resulted in particles of boron nitride to which polydopamine had been attached (hereinafter referred to as polydopamine-modified boron nitride for convenience). The attachment of polydopamine was confirmed by the black-brown coloration of the surfaces of the boron nitride particles.

[0095] Next, the polydopamine-modified boron nitride was heat-treated in an electric furnace at 100° C. for 24 hours, thereby obtaining particles of the composite material of Example 1.

[0096] Example 2 Composite material particles of Example 2 were obtained in the same manner as in Example 1, except that the heat treatment was carried out at 200° C. for 24 hours.

[0097] Example 3 Composite material particles of Example 3 were obtained in the same manner as in Example 1, except that the heat treatment was carried out at 220° C. for 24 hours.

[0098] Example 4 Composite material particles of Example 4 were obtained in the same manner as in Example 1, except that the heat treatment was carried out at 240° C. for 24 hours.

[0099] Example 5 Composite material particles of Example 5 were obtained in the same manner as in Example 1, except that the heat treatment was carried out at 260° C. for 24 hours.

[0100] Example 6 Composite material particles of Example 6 were obtained in the same manner as in Example 1, except that the heat treatment was carried out at 280° C. for 24 hours.

[0101] Example 7 Composite material particles of Example 7 were obtained in the same manner as in Example 1, except that the heat treatment was carried out at 300° C. for 24 hours.

[0102] Example 8 Composite material particles of Example 8 were obtained in the same manner as in Example 1, except that the heat treatment was carried out at 400° C. for 24 hours.

[0103] Comparative Example 1 The particles used in Comparative Example 1 were polydopamine-modified boron nitride obtained by the same method as in Example 1. That is, in Comparative Example 1, the polydopamine-modified boron nitride was used without being subjected to a heat treatment.

[0104] The dielectric loss tangent, infrared absorption spectrum, and N1s spectrum of each of the particles obtained in the above-mentioned Examples and Comparative Examples were evaluated.

[0105] [Measurement of Dielectric Loss Tangent] The dielectric loss tangent at a frequency of 1 GHz was measured for each of the particle groups obtained in Examples 1 to 8 and Comparative Example 1. A cavity resonator (MS46122B, manufactured by AET Co., Ltd.) was used as the measuring device.

[0106] The measurement was carried out to determine whether the dielectric loss tangent was good or not. If the measured value was 0.0040 or less, the dielectric loss tangent was determined to be good, and if it was 0.0030 or less, the dielectric loss tangent was determined to be particularly good.

[0107] [Measurement of Infrared Absorption Spectrum] Each of the particle groups obtained in Examples 1 to 8 and Comparative Example 1 was measured by a diffuse reflectance method using an FT-IR measurement device (Nicolet 6700, manufactured by Thermo Fisher Scientific) at a wave number of 400 cm. -1 From 4000 cm -1 The infrared absorption spectrum was measured under the conditions of: From the obtained infrared absorption spectrum, H B / H A asked for.

[0108] 10 shows the infrared absorption spectra of Examples 1, 2, 7, and 8 and Comparative Example 1. In FIG. 10, the vertical axis represents transmittance (%), and the horizontal axis represents wave number (cm -1) are shown. However, in FIG. 10, the vertical scales are shifted and overlapped to facilitate comparison of the infrared absorption spectra, and the vertical scale is omitted. FIGS. 11A to 11D are enlarged views of the main portions of the infrared absorption spectra of Examples 1, 2, 7, and 8, respectively. As shown in FIGS. 11A to 11D, the higher the temperature of the heat treatment, the more the H A Against H B In other words, the higher the temperature of the heat treatment, the larger H B / H A The value calculated by becomes larger.

[0109] Dielectric loss tangent and H of Examples 1 to 8 and Comparative Example 1 B / H A The results are shown in Table 1 together with the heat treatment temperatures.

[0110]

[0111] [Measurement of N1s spectrum] For each particle group obtained in Examples 1, 2, 7, and 8 and Comparative Example 1, the N1s spectrum was measured using an XPS device (PHI 5000 VersaProbe, manufactured by ULVAC-PHI, Inc.). Monochrome Al-Kα radiation (1486.6 eV) was used as the light source. From the obtained N1s spectrum, the ratio R1 was calculated using the method described above.

[0112] Fig. 12 is a graph showing the N1s spectrum of Example 2. In Fig. 12, the vertical axis represents the intensity of the spectrum (arbitrary unit), and the horizontal axis represents the binding energy (eV).

[0113] The ratios R1 of Examples 1, 2, 7, 8 and Comparative Example 1 are shown in Table 2 together with the temperatures of the heat treatment.

[0114]

[0115] <<Discussion>> As can be seen from Table 1, in the infrared absorption spectrum, 0.66≦H B / H A In Examples 1 to 8, which satisfied the condition 0.70≦H≦1.1, the dielectric loss tangent was 0.0040 or less, which was a good value. B / H AIn Examples 2 to 7, which satisfied the condition of ≦0.90, the dielectric loss tangent was 0.0030 or less, which was a particularly good value.

[0116] As can be seen from Table 2, in Examples 1 to 8 in which the N1s spectrum satisfied 3.0%≦R1≦7.0%, the dielectric loss tangent was 0.0040 or less, which was a good value.

[0117] Although boron nitride was used as the substrate in this example, it is expected that a similar reduction in the dielectric loss tangent can be achieved even when, for example, aluminum nitride, silicon nitride, aluminum oxide, magnesium oxide, or silica is used instead of boron nitride, because the composite material of the present disclosure achieves a reduction in the dielectric loss tangent by reducing the amount of hydrogen-bonded hydroxyl groups contained in the polydopamine coating film and the amount of free hydroxyl groups contained in the polydopamine coating film.

[0118] In order to express the present disclosure, the present disclosure has been appropriately and sufficiently described through the embodiments in the above, but it should be recognized that those skilled in the art can easily change and / or improve the above-described embodiments. Therefore, unless the changes or improvements made by those skilled in the art are at a level that deviates from the scope of the claims described in the claims, the changes or improvements are interpreted as being included in the scope of the claims.

[0119] The composite material of the present disclosure can realize a filler with a reduced dielectric loss tangent, and is therefore suitable for applications such as wiring boards for electronic devices used in high-capacity communications.

[0120] REFERENCE SIGNS LIST 1 Substrate 2 Polydopamine 10 Composite material 20 Resin composition 22 Filler 24 Curable resin 30 Resin-coated film 32 Resin layer 34 Support film 40 Resin-coated metal foil 42 Resin layer 44 Metal foil 50 Metal-clad laminate 52 Insulating layer 54 Metal foil 60 Wiring board 62 Insulating layer 64 Wiring

Claims

1. A substrate; polydopamine attached to the substrate; A composite material comprising: The substrate to which the polydopamine is attached has an infrared absorption spectrum obtained by Fourier transform infrared spectroscopy at 3070 cm －１ Measurement points at 3700 cm －１ When the line connecting the measurement points at is defined as the baseline, 0.66≦H Ｂ / H Ａ ≦1.1, H Ａ is the 3380 cm in the infrared absorption spectrum. －１ indicates the vertical distance from the measurement point to the baseline, H Ｂ is the 3630 cm in the infrared absorption spectrum. －１ indicates the vertical distance from the measurement point at Composite material.

2. 0.70≦H Ｂ / H Ａ ≦0.90, 2. The composite material of claim 1.

3. In the N1s spectrum of the composite material obtained by X-ray photoelectron spectroscopy, the ratio of the area of ​​the peak derived from the nitrogen atom of the primary amino group to the area of ​​the entire N1s spectrum is 3.0% or more and 7.0% or less; 2. The composite material of claim 1.

4. The substrate contains at least one selected from the group consisting of boron nitride, aluminum nitride, silicon nitride, aluminum oxide, magnesium oxide, and silica.

2. The composite material of claim 1.

5. The substrate comprises boron nitride.

5. The composite material of claim 4.

6. Comprising the composite material of claim 1 . Filler.

7. A composition comprising the filler of claim 6. Resin composition.

8. The resin composition according to claim 7 or a semi-cured product of the resin composition, Prepreg.

9. A resin layer comprising the resin composition according to claim 7 or a semi-cured product of the resin composition; A support film, Resin-coated film.

10. A resin layer comprising the resin composition according to claim 7 or a semi-cured product of the resin composition; A metal foil, Metal foil with resin.

11. An insulating layer comprising a cured product of the resin composition according to claim 7 or a cured product of the prepreg according to claim 8; A metal foil, Metal-clad laminate.

12. An insulating layer comprising a cured product of the resin composition according to claim 7 or a cured product of the prepreg according to claim 8; With wiring, wiring board.

13. Depositing polydopamine on a surface of a substrate; heating the substrate and the polydopamine attached to the surface; Including, A method for producing a polydopamine-attached substrate.

14. In the heating, the substrate and the polydopamine are heated to a temperature of 100° C. or more and 400° C. or less. A method for producing a substrate having the polydopamine attached thereto according to claim 13.

15. In the heating, the substrate and the polydopamine are heated to a temperature of 200° C. or more and 300° C. or less. A method for producing a substrate having the polydopamine attached thereto according to claim 13.