Composite material, product resulting from applying said composite material, and method for producing composite material

Abstract

A composite material according to one embodiment of the present disclosure comprises a substrate and a polydopamine that contains multiple hydroxyl groups and at least one acyl group.

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, 5701-5708

[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 comprises: a substrate; and a polydopamine containing a plurality of hydroxyl groups and at least one acyl group.

[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 a first embodiment. FIG. 2A is a diagram illustrating the behavior of an acylating agent when it is added to a substrate having polydopamine attached thereto in a hydrophobic solvent. FIG. 2B is a diagram illustrating the behavior of an acylating agent when it is added to a substrate having polydopamine attached thereto in a hydrophilic solvent. FIG. 3 is a flowchart showing an example of a method for producing a composite material according to the first embodiment. FIG. 4 is a diagram showing a schematic configuration of a resin composition according to a fourth embodiment. FIG. 5 is a cross-sectional view of a resin-coated film according to a sixth embodiment. FIG. 6 is a cross-sectional view of a resin-coated metal foil according to a seventh embodiment. FIG. 7 is a cross-sectional view of a metal-clad laminate according to an eighth embodiment. FIG. 8 is a cross-sectional view of a wiring board according to a ninth embodiment.

[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.

[0014] However, polydopamine has many hydroxyl groups, making it hydrophilic and prone to adsorbing moisture from the atmosphere. Therefore, when boron nitride with polydopamine attached is used as a filler, first, there is a concern that the hydroxyl groups and adsorbed water may cause a deterioration in the dielectric tangent. Second, heating during the solder reflow process can cause the moisture adsorbed on the surface of the polydopamine to evaporate, generating bubbles. These bubbles can accumulate inside the wiring board, potentially causing various problems.

[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 includes: a substrate; and polydopamine containing a plurality of hydroxyl groups and at least one acyl group.

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

[0018] In a second aspect of the present disclosure, for example, in the composite material according to the first aspect, the at least one acyl group may be generated by acylation of at least a portion of the plurality of hydroxyl groups.

[0019] In a third aspect of the present disclosure, for example, in the composite material according to the first aspect, when the number of moles of the hydroxyl groups contained in the polydopamine is defined as N1 and the number of moles of the at least one acyl group contained in the polydopamine is defined as N2, the following relationship may be satisfied: 0.20≦N2 / N1. With the above configuration, the dielectric loss tangent of the composite material can be further reduced.

[0020] In the fourth aspect of the present disclosure, for example, the composite material according to the third aspect may satisfy 0.30≦N2 / N1. With the above configuration, the dielectric loss tangent of the composite material can be further reduced.

[0021] In the fifth aspect of the present disclosure, for example, in the composite material according to the third or fourth aspect, N2 / N1≦0.5 may be satisfied.

[0022] In a sixth aspect of the present disclosure, for example, in the composite material according to any one of the first to fifth 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.

[0023] In a seventh aspect of the present disclosure, for example, in the composite material according to the sixth aspect, the substrate may contain boron nitride. The composite material of the present disclosure is particularly useful when the substrate contains boron nitride.

[0024] A composite material according to an eighth aspect of the present disclosure includes a substrate and polydopamine containing a functional group represented by -OCOR, where R is a hydrocarbon group.

[0025] A filler according to a ninth aspect of the present disclosure includes the composite material according to any one of aspects 1 to 8. According to the above configuration, the dielectric loss tangent of the filler can be reduced.

[0026] A resin composition according to a tenth aspect of the present disclosure includes the filler according to the ninth aspect. According to the tenth aspect, it is possible to provide a resin composition that exhibits a low dielectric loss tangent and excellent heat resistance.

[0027] A prepreg according to an eleventh aspect of the present disclosure includes the resin composition of the tenth aspect or a semi-cured product of the resin composition.

[0028] A resin-coated film according to a twelfth aspect of the present disclosure comprises: a resin layer containing the resin composition of the tenth aspect or a semi-cured product of the resin composition; and a support film.

[0029] A resin-coated metal foil according to a thirteenth aspect of the present disclosure includes: a resin layer containing the resin composition of the tenth aspect or a semi-cured product of the resin composition; and a metal foil.

[0030] A metal-clad laminate according to a fourteenth aspect of the present disclosure comprises: an insulating layer containing a cured product of the resin composition according to the tenth aspect or a cured product of the prepreg according to the eleventh aspect; and a metal foil.

[0031] A wiring board according to a fifteenth aspect of the present disclosure includes: an insulating layer including a cured product of the resin composition according to the tenth aspect or a cured product of the prepreg according to the eleventh aspect; and wiring.

[0032] According to the eleventh to fifteenth aspects, various application products suitable for high frequencies can be provided.

[0033] A method for producing a composite material according to a sixteenth aspect of the present disclosure includes contacting a material containing polydopamine having a plurality of hydroxyl groups with an acylating agent, and acylating at least a portion of the hydroxyl groups, the material including a substrate and the polydopamine attached to a surface of the substrate. This configuration allows for the production of a composite material with a reduced dielectric loss tangent.

[0034] In a seventeenth aspect of the present disclosure, for example, in the method for producing a composite material according to the sixteenth aspect, the acylation may be performed in a hydrophilic solvent. With this configuration, the dielectric loss tangent of the composite material is further reduced.

[0035] In an eighteenth aspect of the present disclosure, for example, in the method for producing a composite material according to the seventeenth aspect, the hydrophilic solvent may contain water. With this configuration, the dielectric loss tangent of the composite material is further reduced.

[0036] In a nineteenth aspect of the present disclosure, for example, in the method for producing a composite material according to any one of the sixteenth to eighteenth aspects, the acylating agent may contain an acid anhydride. With this configuration, the dielectric loss tangent of the composite material is further reduced.

[0037] In a twentieth aspect of the present disclosure, for example, in the method for producing a composite material according to the nineteenth aspect, the acid anhydride may include at least one selected from the group consisting of methacrylic anhydride, acrylic anhydride, acetic anhydride, and benzoic anhydride. This configuration further reduces the dielectric loss tangent of the composite material.

[0038] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0039] First Embodiment Hereinafter, a first embodiment will be described with reference to FIGS. 1 to 3. FIG.

[0040] 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. At least a portion of the hydroxyl groups contained in the polydopamine 2 are acylated.

[0041] 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.

[0042] When a compound having hydroxyl groups, such as polydopamine, is reacted with an acylating agent in the presence of a catalyst, the hydroxyl groups are acylated. In the composite material 10, at least a portion of the hydroxyl groups contained in the polydopamine 2 are acylated. That is, in the composite material 10, the amount of hydroxyl groups contained in the polydopamine 2 is reduced. Therefore, the composite material 10 achieves a reduced dielectric loss tangent.

[0043] Whether or not at least a portion of the hydroxyl groups contained in polydopamine 2 in composite material 10 are acylated can be confirmed, for example, from the infrared absorption spectrum of composite material 10. Specifically, this can be confirmed from the absorption in the infrared absorption spectrum resulting from the stretching vibration of the carbonyl group contained in the acylating agent used for acylation. The infrared absorption spectrum is a spectrum obtained by the diffuse reflectance method of Fourier transform infrared spectroscopy (FT-IR).

[0044] The number of moles of hydroxyl groups contained in polydopamine 2 is defined as N1, and the number of moles of acyl groups contained in polydopamine 2 is defined as N2. In this case, the composite material 10 may satisfy 0.20≦N2 / N1.

[0045] The number of moles N of acyl groups contained in polydopamine 2 reflects the number of moles of acyl groups derived from the acylating agent contained in polydopamine 2. Therefore, the value calculated by N / N indicates the degree to which the acylating agent has reacted with the hydroxyl groups contained in polydopamine 2, i.e., the acylation rate. In this embodiment, since 0.20≦N / N is satisfied, the acylating agent has sufficiently reacted with the hydroxyl groups contained in polydopamine 2. Therefore, a reduction in the dielectric tangent is achieved in composite material 10.

[0046] The number of moles N1 is calculated based on the following formula (1).

[0047] N1 = (W P / X D ) × 2 ... Formula (1)

[0048] In the above formula (1), W P is the mass (g) of polydopamine 2 attached to the substrate 1. X Dis the molar mass (g / mol) of the dopamine monomer, which is 147.1 (g / mol). The number 2 in the above formula (1) is the number of hydroxyl groups contained in the dopamine monomer.

[0049] The number of moles N2 is calculated based on the following formula (2).

[0050] N2 = W A / X A ...Equation (2)

[0051] In the above formula (2), W A is the mass (g) of the acylating agent contained in polydopamine 2. A is the molar mass (g / mol) of the acyl group, specifically, the molar mass (g / mol) of the RCO moiety in the acylating agent represented by (RCO)O.

[0052] W P and W A can be calculated, for example, by thermogravimetric analysis (TGA) under the following conditions: The mass M1 (g) of the substrate 1 before polydopamine 2 is attached and the mass M2 (g) of the substrate 1 after polydopamine 2 is attached are measured. The mass W of polydopamine 2 attached to the substrate 1 is calculated from the difference between the measured values. P The mass M2 (g) of the substrate 1 to which polydopamine 2 is attached before acylation of polydopamine 2 and the mass M3 (g) of the composite material 10 after acylation of polydopamine 2 are measured. The mass W of the acylating agent contained in polydopamine 2 is calculated from the difference between the measured values. A <Conditions> Measurement start temperature: 20°C Heating rate: 5°C / min Heating temperature: 800°C Measurement atmosphere: air Flow rate of gas in measurement atmosphere: 200mL / min

[0053] Note that polydopamine 2 dissolves in a basic solution, so that the substrate 1 to which polydopamine 2 has been attached can be immersed in, for example, an NaOH solution to remove the polydopamine 2 from the substrate 1 and obtain the original substrate 1.

[0054] The composite material 10 may satisfy 0.30≦N2 / N1. According to the above configuration, the dielectric loss tangent of the composite material 10 is further reduced.

[0055] The composite material 10 may satisfy N2 / N1≦0.5. According to the above configuration, the dielectric loss tangent of the composite material 10 is further reduced.

[0056] (Acylating Agent) Acylation is performed using an acylating agent. The acylating agent is not particularly limited as long as it is capable of reacting with polar functional groups, such as hydroxyl groups, contained in polydopamine 2 to acylate them. The acylating agent may be an acid anhydride. Examples of known acylating agents include carboxylic acid anhydrides. More specifically, examples include methacrylic acid anhydride, acetic anhydride, benzoic acid anhydride, and propanoic acid anhydride. The acid anhydride may include at least one selected from the group consisting of methacrylic acid anhydride, acrylic acid anhydride, acetic anhydride, and benzoic acid anhydride. When the acylating agent has a double bond at its terminal, this double bond reacts with the reactive residue of the resin of the insulating layer to form a bond, thereby improving the adhesion between the composite material 10 and the resin. From this perspective, methacrylic acid anhydride or acetic anhydride is particularly desirable as the acylating agent.

[0057] (Solvent) Acylation may be carried out by adding an acylating agent to a solvent. As the solvent, a hydrophilic solvent or a hydrophobic solvent may be used. In the present disclosure, a hydrophilic solvent refers to a solvent that has a high affinity with water, such as a solvent having a hydroxyl group. A hydrophobic solvent refers to a solvent that has a low affinity with water, such as a solvent that does not have a hydroxyl group.

[0058] The solvent may be a hydrophilic solvent. That is, acylation may be carried out by adding an acylating agent to a hydrophilic solvent. Polydopamine 2 exhibits hydrophilicity and therefore tends to swell in a hydrophilic solvent. Therefore, the use of a hydrophilic solvent can promote the penetration of the acylating agent into the interior of the thin film of polydopamine 2. This improves the acylation rate of polydopamine 2.

[0059] 2A and 2B are diagrams illustrating the behavior of the acylating agent 3 when it is added to a substrate 11 to which polydopamine 21 has been attached. FIG. 2A shows an example in which a hydrophobic solvent 4 is used as the solvent. FIG. 2B shows an example in which a hydrophilic solvent 5 is used as the solvent. As shown in FIGS. 2A and 2B, when the acylating agent 3 is added to a substrate 11 to which polydopamine 21 has been attached, at least a portion of the hydroxyl groups contained in the polydopamine 21 are acylated. This reduces the amount of hydroxyl groups contained in the polydopamine 21, thereby achieving a reduction in the dielectric loss tangent. However, as shown in FIG. 2A, when a hydrophobic solvent 4 is used as the solvent, the surface of the thin film of polydopamine 21 is acylated, but penetration of the acylating agent into the interior of the thin film of polydopamine 21 tends to be suppressed. This is because the thin film of polydopamine 21 tends to shrink in the hydrophobic solvent 4 due to the hydrophilic nature of polydopamine 21. 2B, the thin film of polydopamine 21 tends to swell in the hydrophilic solvent 5. Therefore, when the hydrophilic solvent 5 is used as the solvent, the penetration of the acylating agent 3 into the interior of the thin film of polydopamine 21 is promoted. This makes it possible to sufficiently reduce not only the hydroxyl groups present on the surface of the thin film of polydopamine 21 but also the hydroxyl groups present inside the thin film of polydopamine 21.

[0060] The hydrophilic solvent is not particularly limited. Examples of the hydrophilic solvent include water, methanol, isopropanol, dimethyl sulfoxide (DMSO), ethanol, butanol, propanol, and other alcohols. These hydrophilic organic solvents may be used alone or in combination of two or more. Water is particularly desirable as the hydrophilic solvent. When the hydrophilic solvent is water, the acylating agent can be sufficiently penetrated into the thin film of polydopamine 2.

[0061] [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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] [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.

[0066]

[0067] 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.

[0068] 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 .

[0069] 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.

[0070] In this specification, a polymer is considered to be a "polydopamine" even if some of the functional groups derived from dopamine have changed due to binding with other substances. One example of a change in functional group is the loss of a hydroxyl group associated with the substitution of a hydroxyl group of polydopamine with an acyl group of another substance. This substitution is a typical example of the chemical reaction caused by acylation described above.

[0071] [Method for Manufacturing Composite Material] Next, a method for manufacturing the composite material 10 described above will be described.

[0072] 3 is a flowchart showing an example of a method for producing the composite material 10. The method for producing the composite material 10 includes bringing a material containing polydopamine 2 into contact with an acylating agent (step S1) and acylating at least a portion of the hydroxyl groups contained in the polydopamine 2 (step S2). The material containing polydopamine 2 includes a substrate 1 and polydopamine 2 attached to the surface of the substrate 1.

[0073] The material containing polydopamine 2 can be obtained by utilizing the autoxidative polymerization of dopamine to attach polydopamine 2 to the surface of the substrate 1. 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.

[0074] 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.

[0075] In step S1, a material containing polydopamine 2 is contacted with an acylating agent. Examples of the acylating agent are as described above.

[0076] In step S2, for the material containing polydopamine 2, at least a portion of the hydroxyl groups contained in polydopamine 2 is acylated, thereby obtaining a composite material 10.

[0077] Acylation may be carried out by adding an acylating agent to a hydrophilic solvent. Examples of the hydrophilic solvent are as described above. The hydrophilic solvent is preferably water.

[0078] 2B, the thin film of polydopamine 21 tends to swell in the hydrophilic solvent 5. Therefore, when the hydrophilic solvent 5 is used as the solvent, the penetration of the acylating agent 3 into the interior of the thin film of polydopamine 21 is promoted. This makes it possible to sufficiently reduce not only the hydroxyl groups present on the surface of the thin film of polydopamine 21 but also the hydroxyl groups present inside the thin film of polydopamine 21.

[0079] The acylation reaction may be carried out in the presence of a catalyst. Examples of catalysts include DMAP (N,N-dimethylaminopyridine) and aluminum chloride. For example, the acylation reaction proceeds as shown in the following scheme. The following scheme is an example in which a carboxylic acid anhydride is used as the acylating agent. The hydroxyl groups of polydopamine 2 are reacted with the acylating agent in the presence of a catalyst (DMAP). As a result, the hydroxyl groups of polydopamine 2 are acylated.

[0080]

[0081] The reaction temperature and reaction time for acylation are appropriately selected depending on the amounts of catalyst and acylating agent used. The reaction temperature is usually 0°C or higher and 100°C or lower, and may be 5°C or higher and 50°C or lower, or 10°C or higher and 30°C or lower. The reaction time is usually 1 hour or higher and 48 hours or lower, and may be 5 hours or higher and 40 hours or lower, or 10 hours or higher and 30 hours or lower. When the reaction time is 5 hours or longer, acylation proceeds sufficiently, so that the hydroxyl groups contained in polydopamine can be sufficiently reduced. When the reaction time is 40 hours or shorter, a decrease in productivity and an increase in costs can be suppressed.

[0082] 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 acylation, allowing the dielectric loss tangent of composite material 10 to be reduced.

[0083] Second Embodiment A heat dissipating gap filler according to this embodiment includes the composite material 10 according to the first embodiment.

[0084] In the present 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. In addition, it can suppress moisture adsorption to the filler.

[0085] 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-based resin.

[0086] Third Embodiment A filler for thermal grease according to this embodiment includes the composite material 10 according to the first embodiment.

[0087] In this disclosure, a 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. It can also suppress moisture adsorption to the filler.

[0088] 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.

[0089] 4 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] (Embodiment 5) A prepreg according to embodiment 5 comprises the resin composition 20 of embodiment 4 shown in Figure 4 or a semi-cured product thereof, 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.

[0094] 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.

[0095] 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.

[0096] 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.

[0097] (Embodiment 6) Fig. 5 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. 5, 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.

[0098] The resin layer 32 includes the resin composition 20 of the fourth embodiment shown in FIG. 4 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.

[0099] 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.

[0100] Seventh Embodiment Fig. 6 is a cross-sectional view of a resin-coated metal foil 40 according to a seventh embodiment. The resin-coated metal foil 40 includes 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. 6, the metal foil 44 is disposed on the surface of the resin layer 42. However, another layer, such as an adhesive layer, may be disposed between the resin layer 42 and the metal foil 44.

[0101] The resin layer 42 includes the resin composition of the fourth embodiment shown in FIG. 4 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 42 hardens and transforms into an insulating layer. An example of such an insulating layer is the insulating layer of a wiring board.

[0102] 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.

[0103] Eighth Embodiment Fig. 7 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. 4 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.

[0104] 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.

[0105] 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.

[0106] (Embodiment 9) Fig. 8 is a cross-sectional view of wiring board 60 in embodiment 9. Wiring board 60 includes insulating layer 62 and wiring 64. According to this embodiment, it is possible to provide wiring board 60 suitable for high frequencies. Insulating layer 62 includes a cured product of resin composition 20 of embodiment 4 shown in Fig. 4 or a cured product of the prepreg of embodiment 5. Wiring 64 is supported by insulating layer 62. More specifically, wiring 64 is disposed on insulating layer 62. Wiring 64 can be formed by partially removing the metal foil.

[0107] 7 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 that a circuit is formed.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] Next, 2.0 g of polydopamine-modified boron nitride was added to 20 ml of deionized water, and 0.1 g of DMAP was added as a catalyst and dissolved. Next, 2 ml of methacrylic anhydride was added as an acylating agent to obtain a mixed solution. The temperature of the mixed solution was set to 25°C and stirred using a magnetic stirrer for 24 hours. The mixed solution was then filtered to obtain a solid. The obtained solid was washed with toluene and then dried. This yielded particles of the composite material of Example 1.

[0112] Example 2 Composite material particles of Example 2 were obtained in the same manner as in Example 1, except that 2 ml of acetic anhydride was used as the acylating agent instead of 2 ml of methacrylic anhydride.

[0113] Example 3 Composite material particles of Example 3 were obtained in the same manner as in Example 1, except that 2 ml of acrylic anhydride was used as the acylating agent instead of 2 ml of methacrylic anhydride.

[0114] Example 4 Composite material particles of Example 4 were obtained in the same manner as in Example 1, except that 20 ml of chloroform was used as the solvent instead of 20 ml of deionized water.

[0115] 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 treated with an acylating agent.

[0116] The dielectric loss tangent and acylation rate of each of the particles obtained in the above-mentioned Examples and Comparative Examples were evaluated.

[0117] [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 4 and Comparative Example 1. A cavity resonator (MS46122B, manufactured by AET Co., Ltd.) was used as the measuring device.

[0118] The measurement was carried out to determine whether the dielectric loss tangent was good or not. If the measured value was 0.0045 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.

[0119] [Evaluation of Acylation Rate] For each of the particle groups obtained in Examples 1 to 4 and Comparative Example 1, N2 / N1 was determined by the method described above.

[0120] The dielectric loss tangents and N2 / N1 of Examples 1 to 4 and Comparative Example 1 are shown in Table 1, along with the acylating agents and solvents used.

[0121]

[0122] <<Discussion>> As can be seen from Table 1, the composite materials of Examples 1 to 4, in which at least a portion of the hydroxyl groups contained in polydopamine were acylated with an acylating agent, exhibited favorable dielectric loss tangents of 0.0045 or less. The composite materials of Examples 1 to 4 satisfied the condition 0.20≦N2 / N1. The composite materials of Examples 1 to 3, in which water was used as the solvent, exhibited even better dielectric loss tangents of 0.0040 or less. The composite materials of Examples 1 to 3 satisfied the condition 0.35≦N2 / N1.

[0123] In this example, boron nitride was used as the substrate. However, 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. This is because the composite material of the present disclosure achieves a reduction in the dielectric loss tangent by reducing the amount of hydroxyl groups contained in polydopamine.

[0124] 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.

[0125] 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.

[0126] REFERENCE SIGNS LIST 1, 11 Substrate 2, 21 Polydopamine 3 Acylating agent 4 Hydrophobic solvent 5 Hydrophilic solvent 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; a polydopamine comprising a plurality of hydroxyl groups and attached to the substrate; At least one hydrogen atom of the plurality of hydroxyl groups is substituted with an acyl group. Composite material.

2. The acyl group is generated by acylation of at least a portion of the hydroxyl groups.

2. The composite material of claim 1.

3. 0.20≦N ２ / N １ Fulfilling N １ is the number of moles of the hydroxyl groups contained in the polydopamine, N ２ is the number of moles of the acyl group contained in the polydopamine; 2. The composite material of claim 1.

4. 0.30≦N ２ / N １ Fulfilling 4. The composite material of claim 3.

5. N ２ / N １ ≦0.5 is satisfied, 5. A composite material according to claim 3 or 4.

6. 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.

7. The substrate comprises boron nitride; 7. The composite material of claim 6.

8. The polydopamine contains a functional group represented by -OCOR, the functional group includes the acyl group, R is a hydrocarbon group; 2. The composite material of claim 1.

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

10. Comprising the filler of claim 9. Resin composition.

11. The resin composition according to claim 10 or a semi-cured product of the resin composition, Prepreg.

12. A resin layer comprising the resin composition according to claim 10 or a semi-cured product of the resin composition; A support film, Resin-coated film.

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

14. An insulating layer comprising a cured product of the resin composition according to claim 10 or a cured product of the prepreg according to claim 11; A metal foil, Metal-clad laminate.

15. An insulating layer comprising a cured product of the resin composition according to claim 10 or a cured product of the prepreg according to claim 11; With wiring, wiring board.

16. contacting a material comprising a polydopamine containing multiple hydroxyl groups with an acylating agent; acylation of at least a portion of the hydroxyl groups; Including, The material comprises a substrate and the polydopamine attached to a surface of the substrate. Manufacturing methods for composite materials.

17. The acylation is carried out in a hydrophilic solvent. A method for producing the composite material according to claim 16.

18. The hydrophilic solvent comprises water. A method for producing the composite material according to claim 17.

19. The acylating agent comprises an acid anhydride. A method for producing the composite material according to claim 16.

20. The acid anhydride includes at least one selected from the group consisting of methacrylic anhydride, acrylic anhydride, acetic anhydride, and benzoic anhydride. A method for producing the composite material according to claim 19.