Tabular composite material

Abstract

To provide a tabular composite material capable of sufficiently exerting an interference effect between antenna elements when used as a substrate of a micro strip patch array antenna.SOLUTION: A composite material is controlled to maintain a standard deviation of density values of plural areas obtained by dividing within a material, below a prescribed level, so that an interference effect between antenna elements can be fully exerted.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a plate-shaped composite material suitable for use as a substrate for a microstrip patch antenna used in a millimeter wave radar or the like. [Background technology]

[0002] In recent years, the automotive industry has been actively researching and developing ADAS (Advanced Driver Assistance Systems) and autonomous driving, and millimeter-wave radar is becoming increasingly important as a sensing technology that supports these. From the perspectives of small size, high performance, and low cost, the use of "microstrip patch antennas," which are flat antennas with antenna elements (patches) printed on a resin substrate, is promising for automotive millimeter-wave radar, and studies are underway on antenna pattern designs and substrate materials to improve performance.

[0003] One of the promising substrate materials used for these antennas is polytetrafluoroethylene (PTFE), which has a small dielectric tangent, and in order to further improve the mechanical, thermal, and electrical properties, it has been proposed to blend in granular fillers such as boron nitride, silicon dioxide (silica), and titanium oxide (titania), as well as fillers such as glass fiber and carbon fiber (see Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 03-212987 [Patent Document 2] Japanese Patent Application Publication No. 06-119810 Summary of the Invention [Problem to be solved by the invention]

[0005] Microstrip patch antennas have the advantage of being able to achieve high directivity by taking advantage of the interference effect between antenna elements (patches). However, even if one tries to resonate the radio waves emitted from each antenna element, there can be a discrepancy in the wavelengths of the radio waves, preventing the antenna from fully utilizing its effect. The present invention provides a plate-shaped composite material that can fully exert the interference effect between antenna elements when used as a substrate for a microstrip patch antenna or the like. [Means for solving the problem]

[0006] As a result of extensive research into solving the above-mentioned problems, the inventors have discovered that by controlling a composite material so that the density value of each region when it is divided into multiple regions satisfies specific conditions, it is possible to fully utilize the interference effect between antenna elements when used as a substrate for a microstrip patch antenna, etc. That is, the present invention is as follows. <1-1> A plate-shaped composite material containing a resin and at least one selected from the group consisting of a filler and a reinforcing material, wherein the density of each region when divided into a plurality of regions (unit: g / cm 3 ) is a standard deviation of the density calculated from a group of density values ​​collected from the above-mentioned density values ​​of 0.027 or less. <1-2> The plate-shaped composite material according to <1-1>, wherein a variation value of the density calculated by substituting a maximum value, a minimum value, and an average value of the group of density values ​​into a formula ((maximum value-minimum value) / average value×100) is 7.4% or less. <1-3> The plate-shaped composite material according to <1-1> or <1-2>, having a porosity of 3 to 90 volume %. <1-4> The plate-shaped composite material according to any one of <1-1> to <1-3>, comprising the filler, the content of the filler being 10 to 90 mass %. <1-5> The plate-shaped composite material according to any one of <1-1> to <1-4>, comprising the filler, a content of the filler being 57% by mass or less, and a standard deviation of the content calculated from a group of content values ​​obtained by collecting the contents (unit: mass%) of the filler in each of a plurality of regions when the composite material is divided into a plurality of regions is 1.0 or less. <1-6> The plate-shaped composite material according to any one of <1-1> to <1-5>, comprising the reinforcing material, the content of the reinforcing material being 10 to 90 mass %. <1-7> The plate-shaped composite material according to any one of <1-1> to <1-6>, wherein the standard deviation of the dielectric constant calculated from a group of dielectric constant values ​​obtained by collecting the dielectric constants of the respective regions when the composite material is divided into a plurality of regions is 0.02 or less. <1-8> A substrate comprising the plate-shaped composite material according to any one of <1-1> to <1-6>. <1-9> The substrate according to <1-8>, which is for a microstrip patch antenna.

[0007] The present invention can also be expressed as follows. <2-1> Use of a plate-shaped composite material containing a resin and at least one selected from the group consisting of a filler and a reinforcing material as a substrate, the density of each region (unit: g / cm) when divided into a plurality of regions 3 ) is a density value group obtained by collecting the standard deviation of the density calculated from the density value group of 0.027 or less. <2-2> The substrate according to <2-1>, wherein the substrate is for a microstrip patch antenna. Effect of the Invention

[0008] According to the present invention, it is possible to provide a plate-shaped composite material that can fully exert the interference effect between antenna elements when used as a substrate for a microstrip patch antenna or the like. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a conceptual perspective view showing a specific example of a microstrip patch antenna. [Diagram 2] 1 is a conceptual side view showing an interference effect such as resonance of radio waves radiated from a microstrip patch antenna. [Diagram 3] FIG. 1 is a conceptual perspective view showing a substrate divided into a plurality of regions. [Figure 4] 1 is a scanning electron microscope (SEM) image of a porous inorganic fine particle aggregate formed by aggregation of inorganic fine particles having an average primary particle diameter of 5 to 200 nm (photograph substituted for drawing). [Diagram 5] 1 is a conceptual diagram of a ring resonator pattern formed on a substrate with a copper layer using the composite material of Example 1 and a substrate with a copper layer using the composite material of Comparative Example 2. FIG. [Figure 6] 13 is a conceptual diagram of a probe contact pattern for connecting a ring resonator pattern and an evaluation probe. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In explaining the present invention, specific examples will be given. However, the present invention is not limited to the following contents as long as it does not deviate from the spirit of the present invention, and can be modified appropriately.

[0011] <Plate-shaped composite material> The composite material according to one embodiment of the present invention (hereinafter, may be abbreviated as "composite material") is a plate-shaped composite material containing a resin and at least one selected from the group consisting of a filler and a reinforcing material, and when the material is divided into a plurality of regions, the density (unit: g / cm) of each region can be calculated. 3 ) is characterized in that the standard deviation of the density calculated from the density value group collected is 0.027 or less. A microstrip patch antenna (also called a "microstrip patch array antenna") as shown in FIG. 1 has the advantage of being able to obtain high directivity because it can utilize the interference effect between antenna elements (patches) as shown in FIG. 2. However, for example, if the quality of the substrate is poor, even if the radio waves emitted from each antenna element are resonated, there may be a shift in the wavelength between the radio waves, and the effect may not be fully exerted. The inventors of the present invention have clarified that one of the causes is "unevenness" in the composition, etc. within the substrate (especially unevenness in the distribution within the substrate), and that this problem is particularly noticeable in substrates containing fillers or substrates containing reinforcing materials. The incorporation of fillers has the effect of improving the performance of the substrate, but since the fillers are solid, it is difficult to distribute them uniformly within the resin that is the base material, and as a result, it is thought that "unevenness" is likely to occur in the distribution of the fillers themselves and voids. The same is true for the introduction of reinforcing materials, and it is thought that "unevenness" is likely to occur in the distribution of the resin and voids. It is considered that differences in physical properties such as dielectric constant occur within the substrate, and as a result, a shift occurs in the wavelength of radio waves emitted from the antenna elements arranged thereon. This problem of "unevenness" has been confirmed even in existing commercially available substrates containing fillers or existing commercially available substrates containing reinforcing materials (see, for example, Comparative Examples 2 and 3). Therefore, it is important to create a new composite material that solves this problem, especially in the application of microstrip patch antennas (hereinafter sometimes abbreviated as "patch antennas"). The present inventors have focused on "density," which allows a comprehensive understanding of fillers, reinforcing materials, voids, etc., and have found that the interference effect between antenna elements can be fully exerted by controlling the composite material so that the standard deviation of the density value of each region when the material is divided into multiple regions is kept below a certain level. Below, we will explain in detail the contents of "density," "resin," "filler," "reinforcing material," etc. related to "composite material."

[0012] Composite materials are divided into multiple regions and their density (unit: g / cm 3The standard deviation of the density calculated from the density value group collected from the density values ​​of the composite material is 0.027 or less, and "dividing into a plurality of regions" means dividing the composite material into a plurality of regions, either actually or virtually, for analysis, as shown in FIG. 3. The method of dividing the regions of the composite material and the method of measuring the density are not particularly limited, but usually, the composite material is divided (cut) into a plurality of test pieces with a predetermined dimension (the dimensions are usually standardized), which are used as each region, and the mass and volume of each test piece are measured, and the value obtained by dividing the mass by the volume is the density of the region. Since the filler and pores in the composite material are usually very small compared to the test piece, the density value can be obtained stably, but if the error is large, the dimensions of the test pieces are standardized to "10mm x 10mm" for measurement (possible vertical and horizontal dimensions: 2mm, 5mm, 10mm, 20mm, 30mm, 40mm, 50mm, 100mm, etc.). A "density value group" is a set of density numerical values ​​(density values), including density values ​​for the number of regions divided for analysis, and for example, if the number of regions is 10, the number of density value groups will usually be 10. However, it is not necessary to measure the density for all of the divided regions.

[0013] Composite materials are divided into multiple regions and their density (unit: g / cm 3 ) is characterized in that the standard deviation of density calculated from a group of density values ​​collected from the above regions is 0.027 or less, where "standard deviation of density" is a value calculated by substituting the density of each region into the following formula. In other words, "standard deviation of density" is an index for understanding the variation in density between regions of a composite material.

[0014]

number

[0015] The number of regions of the composite material is usually 2 to 100, but is preferably 4 or more, more preferably 8 or more, and is preferably 50 or less, more preferably 30 or less. Within this range, the standard deviation of density can be calculated more accurately.

[0016] The standard deviation of the density of the composite material is 0.027 or less, preferably 0.026 or less, more preferably 0.025 or less, even more preferably 0.024 or less, particularly preferably 0.020 or less, particularly preferably 0.018 or less, most preferably 0.015 or less, and usually 0.001 or more. If it is within the above range, the interference effect between antenna elements is more easily exhibited when the composite material is used as a substrate for a patch antenna or the like.

[0017] The density variation value of the composite material [a numerical value calculated by substituting the maximum, minimum, and average values ​​of the density values ​​into the formula ((maximum value-minimum value) / average value x 100)] is usually 7.4% or less, preferably 7.0% or less, more preferably 6.8% or less, even more preferably 6.5% or less, particularly preferably 6.0% or less, and most preferably 5.0% or less, and is usually 0.1% or more. If it is within the above range, the interference effect between antenna elements is more easily exhibited when it is used as a substrate for a patch antenna or the like.

[0018] When the composite material contains a filler, the standard deviation of the content calculated from the content value group of the filler contents (unit: mass%) of each region when divided into a plurality of regions is preferably 1.0 or less. The standard deviation of the filler content in the composite material is preferably 0.8 or less, more preferably 0.7 or less, even more preferably 0.6 or less, particularly preferably 0.5 or less, most preferably 0.4 or less, and usually 0.01 or more. In addition, when the filler content is 57 mass% or less, the standard deviation of the filler content in the composite material is preferably 0.9 or less, more preferably 0.8 or less, even more preferably 0.7 or less, particularly preferably 0.6 or less, most preferably 0.55 or less, and usually 0.01 or more. Within the above range, the interference effect between antenna elements is more easily exhibited when used as a substrate for a patch antenna, etc.

[0019] When the composite material contains a filler, the variation value of the filler content [a value calculated by substituting the maximum value, minimum value, and average value of the content value group into the formula ((maximum value-minimum value) / average value x 100)] is preferably 11.0% or less. The variation value of the filler content in the composite material is preferably 10.0% or less, more preferably 7.5% or less, particularly preferably 5.0% or less, more preferably 2.8% or less, more preferably 2.6% or less, more preferably 2.4% or less, more preferably 2.2% or less, most preferably 2.0% or less, and usually 0.1% or more. In addition, when the filler content is 57% by mass or less, the variation value of the filler content in the composite material is preferably 11.0% or less, more preferably 10.0% or less, more preferably 7.5% or less, particularly preferably 5.0% or less, most preferably 2.5% or less, and usually 0.1% or more. Within this range, when used as a substrate for a patch antenna or the like, the interference effect between antenna elements is more easily exhibited.

[0020] When the composite material contains a reinforcing material, the standard deviation of the content calculated from a group of content values ​​obtained by collecting the reinforcing material contents (unit: mass%) of each region when the composite material is divided into a plurality of regions is preferably 0.60 or less. The standard deviation of the reinforcing material content in the composite material is preferably 0.58 or less, more preferably 0.56 or less, even more preferably 0.54 or less, particularly preferably 0.52 or less, and most preferably 0.50 or less, and is usually 0.01 or more. If it is within the above range, the interference effect between antenna elements is more easily exhibited when the composite material is used as a substrate for a patch antenna or the like.

[0021] When the composite material contains a reinforcing material, the variation value of the reinforcing material content [a numerical value calculated by substituting the maximum value, minimum value, and average value of the content value group into the formula ((maximum value-minimum value) / average value x 100)] is preferably 3.0% or less. The variation value of the reinforcing material content in the composite material is preferably 2.8% or less, more preferably 2.6% or less, even more preferably 2.4% or less, particularly preferably 2.2% or less, and most preferably 2.0% or less, and is usually 1.4% or more. If it is within the above range, the interference effect between antenna elements is more easily exhibited when used as a substrate for a patch antenna or the like.

[0022] The dielectric constant of the composite material (frequency: 10 GHz) is usually 3.50 or less, preferably 3.00 or less, more preferably 2.50 or less, further preferably 2.25 or less, particularly preferably 2.00 or less, and is usually 1.50 or more. The dielectric constant of the composite material is the numerical value of the real part (εr') calculated by measuring the complex dielectric constant by the cavity resonator perturbation method (measurement frequency: 10 GHz).

[0023] The standard deviation of the dielectric constant of the composite material calculated from a group of dielectric constant values ​​obtained by collecting the dielectric constants of the respective regions when the composite material is divided into a plurality of regions is preferably 0.025 or less. The standard deviation of the dielectric constant of the composite material is preferably 0.02 or less, more preferably 0.015 or less, even more preferably 0.012 or less, particularly preferably 0.01 or less, and most preferably 0.008 or less, and is usually 0.001 or more. If it is within the above range, the interference effect between antenna elements is more easily exhibited when the composite material is used as a substrate for a patch antenna or the like.

[0024] The composite material preferably has a dielectric constant variation value (a numerical value calculated by substituting the maximum, minimum, and average of the dielectric constant values ​​into the formula ((maximum-minimum) / average×100)) of 5.0% or less. The dielectric constant variation value of the composite material is preferably 3.0% or less, more preferably 2.5% or less, even more preferably 2.0% or less, particularly preferably 1.5% or less, and most preferably 1.3% or less, and is usually 0.1% or more. If it is within the above range, the interference effect between antenna elements is more easily exhibited when used as a substrate for a patch antenna or the like.

[0025] The composite material is in the form of a plate, and its thickness is usually 2.0 to 3000 μm, but is preferably 10 μm or more, more preferably 50 μm or more, even more preferably 80 μm or more, and most preferably 100 μm or more, and is preferably 2000 μm or less, more preferably 1000 μm or less, even more preferably 800 μm or less, particularly preferably 600 μm or less, and most preferably 400 μm or less. If it is within the above range, a good relative dielectric constant, etc. of the composite material can be ensured.

[0026] The composite material is preferably divided into a plurality of regions, and the standard deviation of the thickness calculated from a group of thickness values ​​obtained by collecting the thicknesses (unit: μm) of each region is 24 or less. The standard deviation of the thickness of the composite material is preferably 20 or less, more preferably 15 or less, even more preferably 10 or less, particularly preferably 5 or less, and most preferably 3 or less, and is usually 0.1 or more. If it is within the above range, the interference effect between antenna elements is more easily exhibited when the composite material is used as a substrate for a patch antenna or the like.

[0027] The composite material preferably has a thickness variation value (a value calculated by substituting the maximum, minimum, and average values ​​of the thickness values ​​into the formula ((maximum value-minimum value) / average value x 100)) of 20% or less. The thickness variation value in the composite material is preferably 18% or less, more preferably 15% or less, even more preferably 10% or less, particularly preferably 8% or less, and most preferably 6% or less, and is usually 0.1% or more. If it is within the above range, the interference effect between antenna elements is more easily exhibited when used as a substrate for a patch antenna or the like.

[0028] The porosity of the composite material (whole composite material) is usually 3 to 90% by volume, but is preferably 20% by volume or more, more preferably 30% by volume or more, even more preferably 40% by volume or more, particularly preferably 50% by volume or more, and is preferably 80% by volume or less, more preferably 70% by volume or less, and even more preferably 60% by volume or less. Within the above range, the composite material can have good properties such as a dielectric constant and a thermal expansion coefficient. The porosity of the composite material is a value calculated by measuring the density and mass (blended mass) of the resin and the density and mass (blended mass) of the filler, and substituting the true density of the composite material calculated from the measurement results, the bulk density of the composite material, and the density of air into the following formula. Porosity [volume %] = (bulk density [g / cm 3 ]-True density [g / cm 3 ])÷(bulk density [g / cm 3 ]-Air density [g / cm 3 ]) x 100 True density [g / cm 3 ] = mass% of filler × filler density [g / cm 3 ] + resin mass% × resin density [g / cm 3 ]

[0029] The dielectric loss tangent of the composite material (frequency: 10 GHz) is usually 0.01 or less, preferably 0.008 or less, more preferably 0.006 or less, even more preferably 0.004 or less, particularly preferably 0.002 or less, and is usually 0.0005 or more. The dielectric loss tangent of the composite material is defined as the ratio (εr" / εr') of the imaginary part (εr") to the real part (εr') calculated by measuring the complex dielectric constant by the cavity resonator perturbation method (measurement frequency: 10 GHz).

[0030] The thermal expansion coefficient (Z-axis direction) of the composite material is usually 100 ppm / K or less, preferably 90 ppm / K or less, more preferably 80 ppm / K or less, even more preferably 70 ppm / K or less, particularly preferably 60 ppm / K or less, and most preferably 50 ppm / K or less, and is usually 5 ppm / K or more. The thermal expansion coefficient (Z-axis direction) of the composite material is a value calculated from a formula in accordance with Japanese Industrial Standard JIS R3251-1990 using laser interference method (laser thermal dilatometer, measurement temperature range: -50 to 200°C, heating rate: 2°C / min, atmosphere: He, load: 17g).

[0031] The dimensions of the composite material (maximum diameter, vertical or horizontal length) are usually 20 to 1500 mm, but are preferably 30 mm or more, more preferably 40 mm or more, even more preferably 50 mm or more, and most preferably 60 mm or more, and are preferably 1400 mm or less, more preferably 1300 mm or less.

[0032] (resin) The type of resin is not particularly limited, and resins used for substrates and the like can be appropriately adopted, including thermoplastic resins such as fluorine-based resins; and thermosetting resins such as epoxy resins, polyimide resins, and phenolic resins. Among these, fluorine-based resins, epoxy resins, and polyimide resins are preferred, and fluorine-based resins are particularly preferred. With these resins, there is a tendency for the distribution of fillers, reinforcing materials, and voids to be less "uneven," and the features of the present invention can be effectively utilized. In addition, fluorine-based resins exhibit excellent characteristics as substrates for millimeter wave radars. The term "fluorine-based resin" refers to a polymer compound obtained by polymerization of olefins containing fluorine atoms.

[0033] Examples of fluorine-based resins include polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTEF), tetrafluoroethylene-ethylene copolymer (ETFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), and polyvinylidene fluoride (PVDF), with PTFE being particularly preferred. These may be used alone or in combination of two or more. Examples of the epoxy resin include bisphenol type epoxy resins such as bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol E type epoxy resin, bisphenol M type epoxy resin, bisphenol P type epoxy resin, and bisphenol Z type epoxy resin; novolac type epoxy resins such as phenol novolac type epoxy resin and cresol novolac type epoxy resin; biphenyl type epoxy resin, biphenyl aralkyl type epoxy resin, aryl alkylene type epoxy resin, naphthalene type epoxy resin, anthracene type epoxy resin, phenoxy type epoxy resin, dicyclopentadiene type epoxy resin, norbornene type epoxy resin, adamantane type epoxy resin, and fluorene type epoxy resin. Examples of the phenol resin include novolac-type phenol resins such as phenol novolac resin, cresol novolac resin, bisphenol A novolac resin, and triazine skeleton-containing phenol novolac resin; and resol-type phenol resins such as unmodified resol phenol resin and oil-modified resol phenol resin. The polyimide resin can be obtained by reacting an organic tetracarboxylic dianhydride with a diamino compound (diamine) to synthesize a polyimide precursor (polyamic acid), and dehydrating and cyclizing the polyimide precursor. Examples of the organic tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 2,2-bis(2,3-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, and bis(3,4-dicarboxyphenyl)sulfone dianhydride. These organic tetracarboxylic dianhydrides may be used alone or in combination of two or more. Examples of the diamino compound include m-phenylenediamine, p-phenylenediamine, 3,4-diaminodiphenyl ether, 4,4'-diaminophenyl ether, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 2,2-bis(4-aminophenoxyphenyl)propane, 2,2-bis(4-aminophenoxyphenyl)hexafluoropropane, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,4-diaminotoluene, 2,6-diaminotoluene, diaminodiphenylmethane, 4,4'-diamino-2,2-dimethylbiphenyl, 2,2-bis(trifluoromethyl)-4,4'-diaminobiphenyl, etc. These diamino compounds may be used alone or in combination of two or more.

[0034] When the resin is a fluororesin, the fluororesin is preferably "fibrillated (fibrous structured)". The fibers in the fibrillation can be oriented in one direction or multiple directions, but it is more preferable that they are oriented in multiple directions, and it is particularly preferable that the fibrils and inorganic fine particle aggregates described later are linked to form a "three-dimensional fine mesh structure". When the fluororesin is fibrillated, particularly when a three-dimensional fine mesh structure is formed, it is possible to ensure excellent mechanical strength and dimensional stability as a composite material. The fibrillation of the fluororesin can be confirmed by surface observation using an SEM or the like. The fibrillation of the fluororesin can be promoted by applying a shear force, for example, but more specifically, it can be carried out by multi-stage rolling described later, and the three-dimensional fine mesh structure can be formed by different direction multi-stage rolling described later.

[0035] When the resin is a thermosetting resin, a curing accelerator is usually blended in. The "curing accelerator" includes a heat-curing type that accelerates curing by heat and an activation energy ray curing type that cures by activation energy rays such as ultraviolet rays. Examples of the thermosetting curing accelerator include phenol compounds, acid anhydride compounds, amide compounds, hydrazide compounds, imidazoline compounds, urea compounds, polysulfide compounds, etc. Phenol compounds are preferred. These curing agents can be used alone or in combination of two or more. Examples of the activation energy ray-curable curing accelerator include benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators.

[0036] The content of the curing accelerator is usually 0.1 to 10 parts by mass relative to 100 parts by mass of the total of the thermosetting resins, and is preferably 0.2 parts by mass or more, preferably 0.3 parts by mass or more, more preferably 0.4 parts by mass or more, even more preferably 0.5 parts by mass or more, and particularly preferably 0.6 parts by mass or more, and is usually 9 parts by mass or less, preferably 8 parts by mass or less, more preferably 7 parts by mass or less, even more preferably 6 parts by mass or less, and particularly preferably 5 parts by mass or less.

[0037] (Filler) The type of filler is not particularly limited, but includes granular fillers and fibrous fillers. Granular fillers include solid carbon such as carbon black and graphite; silicon dioxide (silica) such as porous silica, fused silica, and silica gel; transition metal oxides (including composite oxides) such as titanium oxide (titanium dioxide (titania) and the like), iron oxide, and zirconium oxide (zirconium dioxide (zirconia)); and nitrides of typical elements such as boron nitride and silicon nitride. Fibrous fillers include glass fiber and carbon fiber. Hollow inorganic particles such as silica balloons and glass balloons are also included. These can be used alone or in combination of two or more kinds, but granular fillers are preferred.

[0038] The amount of the filler in the composite material is usually 10 to 90 parts by mass, preferably 20 parts by mass or more, preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, particularly preferably 50 parts by mass or more, and usually 85 parts by mass or less, preferably 80 parts by mass or less, more preferably 75 parts by mass or less, even more preferably 70 parts by mass or less, and particularly preferably 65 parts by mass or less, when the total of the resin and the filler (including the reinforcing material when the reinforcing material is included) is taken as 100 parts by mass. The content of the filler in the composite material (actual measured value) is usually 10 to 90% by mass, preferably 20 parts by mass or more, preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 45 parts by mass or more, and particularly preferably 50 parts by mass or more, and usually 85% by mass or less, preferably 80% by mass or less, more preferably 75% by mass or less, even more preferably 70% by mass or less, and particularly preferably 65% ​​by mass or less. In addition, when a composite material is divided into a plurality of regions, the filler content of each region usually varies, so the "filler content" refers to the average value. If the filler content is within the above range, the composite material can exhibit good properties such as a dielectric constant and a thermal expansion coefficient.

[0039] The filler preferably contains "porous inorganic fine particle aggregates formed by agglomeration of inorganic fine particles having an average primary particle diameter of 5 to 200 nm (hereinafter, sometimes abbreviated as "inorganic fine particle aggregates")" and nonporous inorganic fine particles. The inorganic fine particle aggregate is specifically as shown in the SEM photographed image of FIG. 4, and means an aggregate formed by fusing a plurality of inorganic fine particles, and has voids between the inorganic fine particles, making it porous. The inorganic fine particles in the aggregate may be fused at the time of formulation, and may be unfused by subsequent mixing with a fluorine-based resin, etc. On the other hand, the "nonporous" of nonporous inorganic fine particles is an expression for "porous", which is characteristic of inorganic fine particles, and nonporous inorganic fine particles may be inorganic fine particles that are not "porous". In other words, nonporous inorganic fine particles do not need to be completely free of pores, and may have pores as long as they are not recognized as "porous". The "aggregates of inorganic fine particles" and "nonporous inorganic fine particles" will be described in detail below.

[0040] Examples of the material of the inorganic fine particles in the inorganic fine particle aggregate include oxides of typical elements such as silicon oxide (silicon monoxide, silicon dioxide (silica), etc.) and aluminum oxide (alumina) (including composite oxides); transition metal oxides such as titanium oxide (titanium dioxide (titania)), iron oxide, and zirconium oxide (zirconium dioxide (zirconia)) (including composite oxides); and nitrides of typical elements such as boron nitride and silicon nitride, which can be used alone or in combination of two or more. Among them, oxides of typical elements are preferred, and silicon dioxide (silica) is particularly preferred. When an oxide of a typical element is used, the relative dielectric constant of the composite material can be kept extremely low, and the composite material can be produced at a lower cost. The crystallinity of the inorganic fine particles is not particularly limited, but silicon dioxide is usually amorphous.

[0041] The average primary particle diameter of the inorganic fine particle aggregate is 5 to 200 nm, preferably 10 nm or more, more preferably 15 nm or more, even more preferably 20 nm or more, and preferably 150 nm or less, more preferably 120 nm or less, even more preferably 100 nm or less, particularly preferably 80 nm or less, and most preferably 70 nm or less. Within the above range, the inorganic fine particle aggregate is not easily broken even when subjected to processing such as mixing, molding, rolling, etc., and good voids can be secured between the inorganic fine particles, and a smooth surface can be easily secured as a plate-shaped composite material. The average primary particle diameter of the inorganic fine particle aggregate is a numerical value obtained by measuring the particle diameter by observation with a SEM and averaging the measured values. Specifically, the procedure is to randomly select inorganic fine particle aggregates (100 pieces), measure the average primary particle diameter (length of the long side of the particle) of each, and average the obtained particle diameters to obtain a numerical value.

[0042] The BET specific surface area of ​​inorganic fine particle aggregates is usually 0.1 m 2 / g or more, preferably 0.5m 2 / g or more, more preferably 1m 2 / g or more, more preferably 5m2 / g or more, usually 250m 2 / g or less, preferably 240m 2 / g or less, more preferably 210m 2 / g or less, more preferably 150m 2 / g or less, particularly preferably 80m 2 / g or less. Within this range, a high porosity can be ensured as a composite material, and an increase in the dielectric tangent can be suppressed. In particular, if the BET specific surface area is too high, the dielectric tangent of the composite material tends to be high. The BET specific surface area of ​​the inorganic fine particle aggregate is a value calculated by substituting the gas adsorption amount measured by a gas adsorption method (particularly nitrogen adsorption isotherm) into the BET formula, and is expressed as a value before being used to manufacture a composite material.

[0043] The apparent specific gravity of the inorganic fine particle aggregate is usually 10 g / L or more, preferably 20 g / L or more, more preferably 30 g / L or more, and even more preferably 40 g / L or more, and usually 100 g / L or less, preferably 90 g / L or less, more preferably 80 g / L or less, even more preferably 70 g / L or less, and particularly preferably 60 g / L or less. Within the above range, a high porosity can be ensured as a composite material, and the inorganic fine particle aggregate is less likely to be broken. The apparent specific gravity of the inorganic fine particle aggregate is determined by filling the inorganic fine particle aggregate in a container capable of measuring the volume, such as a 250 mL graduated cylinder, measuring the filling mass (Xg) and filling volume (YmL) of the inorganic fine particle aggregate, and dividing the filling mass by the filling volume ([apparent specific gravity (g / L)] = X / Y × 1000).

[0044] As inorganic fine particle aggregates, commercially available products such as the Mizukasil series (manufactured by Mizusawa Chemical Industry Co., Ltd.), the Sylysia series (manufactured by Fuji Silysia Corporation), the hydrophobic AEROSIL series (manufactured by Nippon Aerosil Co., Ltd.), and the Nipseal series (manufactured by Tosoh Silica Corporation) can be suitably used, and among these, hydrophobic fumed silica from the hydrophobic AEROSIL series (manufactured by Nippon Aerosil Co., Ltd.) is particularly preferred.

[0045] Examples of the material of the nonporous inorganic fine particles include oxides of typical elements such as silicon oxide (silicon monoxide, silicon dioxide (silica), etc.) and aluminum oxide (alumina) (including composite oxides); transition metal oxides such as titanium oxide (titanium dioxide (titania)), iron oxide, and zirconium oxide (zirconium dioxide (zirconia)) (including composite oxides); and nitrides of typical elements such as boron nitride and silicon nitride. Examples of composite oxides include cordierite, talc, wollastonite, mullite, steatite, and forsterite. The material of the nonporous inorganic fine particles is not limited to one type, and two or more types may be combined.

[0046] The average primary particle diameter of the nonporous inorganic fine particles is 0.2 to 50 μm, preferably 0.3 μm or more, more preferably 0.4 μm or more, even more preferably 0.5 μm or more, and preferably 40 μm or less, more preferably 30 μm or less, even more preferably 20 μm or less, particularly preferably 10 μm or less, and most preferably 5 μm or less. Within the above range, a moderate specific surface area is obtained, and a good dielectric tangent can be secured, and the surface of the composite material is easily made smooth, making it a material more suitable for high frequency substrates. The average primary particle diameter of the nonporous inorganic fine particles is a numerical value obtained by measuring the particle diameter by observation with a SEM and averaging the measured values. Specifically, the procedure is as follows: inorganic fine particle aggregates (100 pieces) are randomly selected, the average primary particle diameter (the major axis of the particle) of each is measured, and the obtained particle diameters are averaged to obtain a numerical value.

[0047] The BET specific surface area of ​​non-porous inorganic particles is usually 0.1 m 2 / g or more, preferably 0.5m 2 / g or more, more preferably 1m 2 / g or more, more preferably 2m 2 / g or more, usually 30m 2 / g or less, preferably 25m 2 / g or less, more preferably 20m 2 / g or less, more preferably 15m 2 / g or less, particularly preferably 10m 2 / g or less. Within this range, a good dielectric tangent can be ensured, and the surface of the composite material is easily made smooth, making the material more suitable for use as a substrate for high frequencies. The BET specific surface area of ​​the nonporous inorganic fine particles is a value calculated by substituting the amount of gas adsorption measured by a gas adsorption method (particularly nitrogen adsorption isotherm) into the BET formula, and is expressed as a value before use in the production of a composite material.

[0048] The dielectric constant of the nonporous inorganic fine particles is usually 10 or less, preferably 8 or less, more preferably 7 or less, even more preferably 6 or less, particularly preferably 5 or less, and is usually at least 3. The dielectric constant of the nonporous inorganic fine particles is a value determined by a method in accordance with Japanese Industrial Standard JIS C2565.

[0049] Commercially available nonporous inorganic fine particles include fused silica such as SFP-130MC, SFP-30M, FB-3SDC manufactured by Denka Corporation; cordierite such as cordierite powder FINE type, ELP-150N, ELP-325N manufactured by AGC Ceramics Co., Ltd.; boron nitride such as FS-1, HP-P1, HP40J series manufactured by Mizushima Ferroalloy Co., Ltd.; and talc such as Nano Ace D-600, D-800, D-1000, FG-15 manufactured by Nippon Talc Co., Ltd.

[0050] The mass ratio of the content of nonporous inorganic microparticles to the total content of inorganic microparticle aggregates and nonporous inorganic microparticles (content of nonporous inorganic microparticles / (content of inorganic microparticle aggregates+content of nonporous inorganic microparticles)) is usually 0.15 to 0.90, preferably 0.2 or more, more preferably 0.3 or more, even more preferably 0.4 or more, and most preferably 0.5 or more, and preferably 0.8 or less, more preferably 0.75 or less, even more preferably 0.7 or less, and most preferably 0.65 or less.

[0051] The composite material may contain materials other than the above-mentioned resins and fillers, but the total content of the resins and fillers in the composite material is usually 60 mass% or more, preferably 70 mass% or more, more preferably 80 mass% or more, even more preferably 90 mass% or more, and particularly preferably 100 mass%.

[0052] From the viewpoint of dielectric loss tangent, the filler (including inorganic fine particle aggregates and nonporous inorganic fine particles) is preferably surface-modified with a surface modifier having a hydrophobic group (hereinafter, sometimes abbreviated as "surface modifier"). However, when filling a thermosetting resin, a surface modifier having a functional group other than a hydrophobic group can also be selected to prevent the filler from agglomerating. The modification with the "surface modifier" will be described in detail below.

[0053] The hydrophobic group of the surface modifier is a fluoro group (-F), a hydrocarbon group (-C n H 2n+1 (n=1 to 30)), among which a fluoro group that exhibits liquid repellency not only to water but also to oily agents is particularly preferred. The surface modifier may be one that chemically adsorbs (reacts) to the surface of the filler, or one that physically adsorbs to the surface of the filler, and may be a low molecular weight compound or a high molecular weight compound. The surface modifier that chemically adsorbs (reacts) to the surface of the filler usually has a reactive functional group that reacts with the surface functional group of the filler (hydroxyl group (-OH) etc.), and examples of the reactive functional group include an alkoxysilyl group (-SiOR (R has 1 to 6 carbon atoms)), a chlorosilyl group (-SiCl), a bromosilyl group (-SiBr), a hydrosilyl group (-SiH) and the like. The method of modifying the surface of the filler with the surface modifier can be appropriately adopted from known methods, and examples thereof include contacting the filler with the surface modifier.

[0054] The surface modifiers can be used alone or in combination of two or more kinds. For example, a surface modifier of a low molecular weight compound having a reactive functional group may be reacted with the surface of the filler, and then a surface modifier of a high molecular weight compound having a hydrophobic group may be physically adsorbed thereon. If the filler material is silicon dioxide (silica) or the like, it may dissolve (decompose) when exposed to a basic aqueous solution, but by modifying it in this way, it is possible to increase the resistance to the basic aqueous solution.

[0055] The thermal decomposition temperature of the surface modifier is usually 250° C. or higher, preferably 300° C. or higher, more preferably 350° C. or higher, even more preferably 360° C. or higher, and particularly preferably 370° C. or higher. Within the above range, decomposition can be suppressed even when treatment such as high-temperature heating is performed. The thermal decomposition temperature of the surface modifier is defined as the temperature at which the weight is reduced by 5% when the temperature is increased at 20° C. / min by thermogravimetry-dependent thermogravimetry analysis (TG-DTA).

[0056] Examples of surface modifiers that are low molecular weight compounds having a fluoro group and a reactive functional group include those represented by the following formula: The compounds represented by the following formula are commercially available and can be obtained as appropriate and used as surface modifiers. [ka]

[0057] Examples of the surface modifying agent of a polymer compound having a fluoro group include those represented by the following formula: [ka]

[0058] A commercially available solution may be used as the surface modifier, and a suitable example is Novec (registered trademark) 2202 manufactured by 3M. Novec (registered trademark) 2202 contains a polymeric compound having a fluoro group, and it has been announced that it contains a "fluoroalkylsilane polymer." When Novec (registered trademark) 2202 is used as a surface modifier, it has the advantage that the critical liquid repellency tension of the composite material can be easily reduced by a relatively simple operation.

[0059] Examples of functional groups other than hydrophobic groups of surface modifiers include glycidyl groups (-C2H3O), hydroxyl groups (-OH), amino groups (-NH2), carboxyl groups (-COOH), and mercapto groups (-SH). In general, functional groups that form bonds with functional groups in the resin or have similar polarity to the functional groups in the resin are selected. Commercially available products include silane coupling agents, such as N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-mercaptopropylmethyldimethoxysilane.

[0060] The content of the surface modifier in the filler (content of organic matter) is usually 0.1 mass% or more, preferably 1 mass% or more, more preferably 2 mass% or more, even more preferably 3 mass% or more, and particularly preferably 4 mass% or more, and is usually 50 mass% or less, preferably 40 mass% or less, more preferably 30 mass% or less, even more preferably 25 mass% or less, and particularly preferably 20 mass% or less.

[0061] (Reinforcement) The reinforcing material means a plate-like material that plays a role in reinforcing the mechanical properties of a composite material, and when the composite material is used as an electronic circuit board, it corresponds to the so-called "substrate (support)". The material of the reinforcing material is not particularly limited, but examples of the material of the reinforcing material include glass, resin fiber, cellulose, etc., and more specific examples include glass cloth, woven fabric, nonwoven fabric, paper, etc., and glass cloth is particularly preferred.

[0062] The thickness of the reinforcing material (the thickness of one layer of the reinforcing material regardless of whether multiple layers of the reinforcing material are filled) is usually 1 to 500 μm, but is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 30 μm or more, and most preferably 50 μm or more, and is preferably 400 μm or less, more preferably 300 μm or less, even more preferably 250 μm or less, particularly preferably 200 μm or less, and most preferably 150 μm or less.

[0063] The amount of the reinforcing material in the composite material is usually 10 to 90 parts by mass, preferably 20 parts by mass or more, preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, particularly preferably 60 parts by mass or more, and usually 85 parts by mass or less, preferably 80 parts by mass or less, more preferably 78 parts by mass or less, even more preferably 73 parts by mass or less, and particularly preferably 70 parts by mass or less. The content (actual value) of the filler in the composite material is usually 10 to 90% by mass, preferably 20 parts by mass or more, preferably 30 parts by mass or more, more preferably 40 parts by mass or more, even more preferably 50 parts by mass or more, particularly preferably 60 parts by mass or more, and usually 85% by mass or less, preferably 80% by mass or less, more preferably 78% by mass or less, even more preferably 73% by mass or less, and particularly preferably 70% by mass or less. When it is within the above range, the composite material can exhibit good properties such as relative dielectric constant and thermal expansion coefficient.

[0064] (Applications of composite materials) The use of the composite material is not particularly limited, but is preferably an electronic circuit board, more preferably a circuit board for a mobile phone, a computer, etc., a substrate for a microstrip patch antenna for a millimeter wave radar, etc. That is, a substrate (hereinafter sometimes abbreviated as "substrate") containing the above-mentioned composite material is also an embodiment of the present invention.

[0065] The substrate comprises a composite material, and preferably has a layer comprising a thermoplastic resin attached to one or both sides of the composite material, and a fluorine-based resin is particularly preferred as the thermoplastic resin. Examples of fluorine-based resins include polytetrafluoroethylene (PTFE, melting point: 327°C), perfluoroalkoxyalkane (PFA, melting point: 310°C), tetrafluoroethylene-hexafluoropropylene copolymer (FEP, melting point: 260°C), polychlorotrifluoroethylene (PCTEF, melting point: 220°C), tetrafluoroethylene-ethylene copolymer (ETFE, melting point: 270°C), chlorotrifluoroethylene-ethylene copolymer (ECTFE, melting point: 270°C), and polyvinylidene fluoride (PVDF, melting point: 151 to 178°C), with PTFE and PFA being particularly preferred. These may be used alone or in combination of two or more.

[0066] The thickness of the resin layer is usually 0.050 to 30 μm, but is preferably 0.100 μm or more, more preferably 0.40 μm or more, even more preferably 1.0 μm or more, and most preferably 1.5 μm or more, and is preferably 20 μm or less, more preferably 10 μm or less, even more preferably 8.0 μm or less, particularly preferably 6.0 μm or less, and most preferably 5.0 μm or less. The substrate is exposed to various chemicals used in the manufacturing process of antennas and the like. For example, when exposed to a highly penetrating treatment liquid, the treatment liquid may penetrate into the substrate, causing poor appearance and changes in characteristics. Since the resin layer also has the function of suppressing the penetration of the treatment liquid, if the thickness is within the above range, peeling of the conductor layer and the like can be effectively suppressed, and poor appearance and changes in characteristics are unlikely to occur even when exposed to a highly penetrating treatment liquid used in the manufacture of electronic circuit boards. The thickness of the resin layer means a numerical value obtained by measuring the distance from the end of the resin layer in the thickness direction to the interface between the composite material and the resin layer at about 5 to 10 points and averaging the measured values.

[0067] The resin layer may be laminated (attached) not only on one side of the composite material, but also on both sides of the composite material.

[0068] The substrate is usually provided with a conductor layer, which is usually a metal layer. If the substrate has a resin layer, the conductor layer is laminated on the resin layer. Examples of the metal species of the metal layer include gold (Au), silver (Ag), platinum (Pt), copper (Cu), aluminum (Al), and alloys containing these metal species. The thickness of the metal layer is usually 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more, and usually 50 μm or less, preferably 45 μm or less, more preferably 40 μm or less.

[0069] The maximum height Rz of the contact surface of the conductor layer with the composite material or resin layer is usually 0.020 μm or more, preferably 0.050 μm or more, more preferably 0.10 μm or more, even more preferably 0.20 μm or more, and particularly preferably 0.30 μm or more, and is usually 10 μm or less, preferably 8.0 μm or less, more preferably 6.0 μm or less, even more preferably 4.0 μm or less, and particularly preferably 2.0 μm or less. The "maximum height Rz" means a value determined by a method conforming to the Japanese Industrial Standard JIS B0601:2013 (a Japanese Industrial Standard created without changing the technical content of the International Organization for Standardization standard ISO4287). In addition, the "maximum height Rz of the contact surface of the conductor layer with the composite material or resin layer" may be directly measured, or the maximum height Rz of the material used for the conductor layer may be used as it is.

[0070] The thickness obtained by subtracting the maximum height Rz of the conductor layer from the thickness of the resin layer ((thickness of resin layer) - (maximum height Rz of conductor layer)) is usually 0.005 μm or more, preferably 0.010 μm or more, more preferably 0.050 μm or more, even more preferably 0.10 μm or more, and particularly preferably 0.50 μm or more, and is usually 29.98 μm or less, preferably 20 μm or less, more preferably 15 μm or less, even more preferably 10 μm or less, and particularly preferably 5.0 μm or less. If it is within the above range, the thickness of the resin layer is sufficiently ensured, so that poor appearance and changes in characteristics are unlikely to occur even when exposed to highly penetrative treatment solutions used in the manufacture of electronic circuit boards.

[0071] (Method of manufacturing composite materials) The composite material contains a resin and at least one selected from the group consisting of a filler and a reinforcing material, and preferably contains at least a filler. The method for producing the composite material is not particularly limited, and the composite material can be produced by appropriately adopting known knowledge. However, in order to keep the standard deviation of density low, when the resin is a thermoplastic resin such as a fluorine-based resin, it is preferable to use a production method that focuses on at least one of the following viewpoints (1) to (3). (1) The particle size ratio of the average particle size of the granulated resin and the granulated filler to be prepared is controlled. By controlling the particle size ratio between the average particle sizes of the granulated resin and the granulated filler, it becomes easier to distribute the filler uniformly within the base resin. (2) Applying physical stress when mixing the resin granules and the filler granules. By applying a physical load when mixing the granulated resin and granulated filler, the particle sizes of the granulated resin and granulated filler become uniform, making it easier to distribute the filler uniformly within the base resin. (3) Uniform pressure is applied to the plate-shaped composite material. By applying uniform pressure across the surface of a plate-shaped composite material, the density, thickness, etc. tend to become uniform.

[0072] On the other hand, when the resin is a thermosetting resin such as an epoxy resin, it is preferable to adopt a production method that focuses on at least one of the following aspects (1') to (4'). (1') Controlling the average particle size of the granulated filler. By controlling the average particle size of the granulated filler, it becomes easier to distribute the filler uniformly within the base resin. (2') Applying physical stress when mixing the granulated filler. By applying a physical load when mixing the filler with the resin before heat curing, the particle size of the granulated filler becomes uniform, making it easier to distribute the filler uniformly within the base resin. (3') The filler is surface-modified. By modifying the surface of the filler with a functional group that has a polarity similar to that of the base material, the filler can be prevented from agglomerating and can be easily dispersed uniformly within the base resin. (4') Uniform pressure is applied to the plate-shaped composite material. By applying uniform pressure across the surface of a plate-shaped composite material before it hardens, the density, thickness, etc. tend to become uniform.

[0073] When a reinforcing material is further contained, it is preferable to adopt a production method that focuses on at least one of the following aspects (1") to (3"). (1") The volume ratio of resin to reinforcing material within the surface is kept constant. By making the in-plane distribution of resin and reinforcing material in a composite material constant, the density of the reinforcing material and resin becomes more uniform. Specific methods include using reinforcing material with a more uniform thickness and less unevenness, and overlapping multiple reinforcing materials to compensate for the in-plane thickness variation of the reinforcing material. (2") Improves adhesion between reinforcing material and resin. By improving the adhesion between the reinforcing material and the resin, it is possible to reduce the number of pores between the reinforcing material and the resin, making it easier to achieve uniform density, thickness, etc. Specific methods include performing surface modification on the surface of the reinforcing material with a polarity similar to that of the base material to increase the wettability of the resin to the reinforcing material, and degassing during the manufacturing process of the resin and reinforcing material. (3) Apply pressure uniformly across the surface of the plate-shaped composite material before it is heat-cured.

[0074] When the resin of the composite material is a thermoplastic resin, a manufacturing method of the composite material (hereinafter sometimes abbreviated as "manufacturing method of the composite material") including the following resin preparation step, filler preparation step, mixing step, molding step, and rolling step is preferred. A resin preparation process for preparing a thermoplastic resin (hereinafter, may be abbreviated as "resin preparation process"). A filler preparation process for preparing a filler (hereinafter, may be abbreviated as "filler preparation process"). A mixing step of mixing the thermoplastic resin, the filler, and the volatile additive to obtain a precursor composition (hereinafter, sometimes abbreviated as "mixing step"). A molding step of molding the precursor composition to obtain a rollable object (hereinafter, may be abbreviated as "molding step"). A rolling process (hereinafter, sometimes abbreviated as "rolling process") in which the rolled object is rolled to obtain a composite material. The "resin preparation step," "filler preparation step," "mixing step," "molding step," "rolling step," and other steps when the resin of the composite material is a thermoplastic resin will be described in detail below.

[0075] The resin preparation step is a step of preparing a thermoplastic resin, and the thermoplastic resin may be obtained or produced by the user. The median diameter d50 of the prepared thermoplastic resin granules (particles after secondary particles) is usually 0.5 μm or more, preferably 1.0 μm or more, more preferably 10 μm or more, and even more preferably 30 μm or more, and is usually 700 μm or less, preferably 300 μm or less, more preferably 150 μm or less, even more preferably 100 μm or less, and particularly preferably 50 μm or less. Within the above range, it becomes easier to uniformly disperse the resin and the filler, and it becomes easier to keep the standard deviation of the density when the composite material is divided into multiple regions low. The thermoplastic resin granules can be determined by a method conforming to Japanese Industrial Standard JIS Z 8825:2001.

[0076] The filler preparation step is a step of preparing a filler, and the filler (including inorganic fine particle aggregates) may be obtained or produced by the user. The median diameter d50 of the granulated filler (secondary particles or later particles) to be prepared is usually 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 3 μm or more, and usually 500 μm or less, preferably 200 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, and particularly preferably 20 μm or less. Within the above range, it becomes easier to uniformly disperse the resin and the filler, and it becomes easier to keep the standard deviation of the density when the composite material is divided into multiple regions low. The particle diameter of the granulated filler can be determined by a method conforming to Japanese Industrial Standard JIS Z 8825:2001. In addition, the filler is preferably surface-modified with the above-mentioned surface modifier.

[0077] The particle size ratio of the average particle sizes of the prepared resin granules and filler granules (median size d50 of thermoplastic resin / median size d50 of filler) is usually 150 or less, preferably 100 or less, more preferably 60 or less, even more preferably 40, particularly preferably 30 or less, and most preferably 10 or less, and is usually 1 or more. If it is within the above range, it becomes easier to uniformly disperse the resin and filler, and it becomes easier to keep the standard deviation of density low when the composite material is divided into multiple regions. The term "average particle size" used herein means the particle size (median size) at an integrated value of 50% in the particle size distribution determined by a laser diffraction method in accordance with Japanese Industrial Standard JIS Z 8825:2001.

[0078] The mixing step is a step of mixing a thermoplastic resin, a filler, and a volatile additive to obtain a precursor composition. The mixing can be carried out by appropriately adopting a known method such as a dry method or a wet method, or by using a mixer, etc. In the case of a dry process, the rotation speed (circumferential speed) of the stirrer or the like is usually 0.5 m / sec or more, preferably 1 m / sec or more, more preferably 5 m / sec or more, even more preferably 10 m / sec or more, and particularly preferably 15 m / sec or more, and is usually 200 m / sec or less, preferably 180 m / sec or less, more preferably 140 m / sec or less, even more preferably 100 m / sec or less, particularly preferably 50 m / sec or less, and most preferably 20 m / sec or less. If it is within the above range, it becomes easier to uniformly disperse the resin and filler, and it becomes easier to keep the standard deviation of density low when the composite material is divided into multiple regions.

[0079] In the case of a dry mixing method, the mixing time is usually 10 seconds or more, preferably 20 seconds or more, more preferably 30 seconds or more, even more preferably 40 seconds or more, particularly preferably 1 minute or more, and most preferably 5 minutes or more, and usually 60 minutes or less, preferably 50 minutes or less, more preferably 40 minutes or less, even more preferably 30 minutes or less, particularly preferably 20 minutes or less, and most preferably 15 minutes or less. Within the above range, the resin and filler can be easily dispersed uniformly, and the standard deviation of the density when the composite material is divided into a plurality of regions can be easily suppressed.

[0080] In the case of a wet method, the rotation speed (peripheral speed) of the stirrer or the like is usually 1 m / sec or more, preferably 5 m / sec or more, more preferably 10 m / sec or more, even more preferably 15 m / sec or more, particularly preferably 20 m / sec or more, and most preferably 25 m / sec or more, and is usually 160 m / sec or less, preferably 130 m / sec or less, more preferably 100 m / sec or less, even more preferably 80 m / sec or less, particularly preferably 60 m / sec or less, and most preferably 40 m / sec or less. If it is within the above range, it becomes easy to uniformly disperse the resin and filler, and it becomes easy to keep the standard deviation of the density when the composite material is divided into a plurality of regions low.

[0081] In the case of a wet mixing method, the mixing time is usually 5 seconds or more, preferably 10 seconds or more, more preferably 20 seconds or more, even more preferably 30 seconds or more, particularly preferably 40 seconds or more, and most preferably 50 seconds or more, and is usually 60 minutes or less, preferably 50 minutes or less, more preferably 40 minutes or less, even more preferably 20 minutes or less, particularly preferably 10 minutes or less, and most preferably 5 minutes or less. Within the above range, the resin and filler can be easily dispersed uniformly, and the standard deviation of the density when the composite material is divided into a plurality of regions can be easily kept low.

[0082] The volatile additive has the function of forming sufficient pores in the composite material by finally volatilizing and removing it. The volatile additive means a compound that has a boiling point of 30 to 300°C and is liquid at room temperature (25°C), and the boiling point of the volatile additive is preferably 50°C or higher, more preferably 100°C or higher, and even more preferably 200°C or higher, and is preferably 280°C or lower, more preferably 260°C or lower, and even more preferably 240°C or lower.

[0083] The types of volatile additives include low-reactivity hydrocarbons, ethers, esters, alcohols, etc., but aliphatic saturated hydrocarbons are preferred. Specific examples include hexane (boiling point: 69°C), heptane (boiling point: 98°C), octane (boiling point: 126°C), nonane (boiling point: 151°C), decane (boiling point: 174°C), undecane (boiling point: 196°C), dodecane (boiling point: 215°C), tridecane (boiling point: 234°C), tetradecane (boiling point: 254°C), etc., with dodecane being particularly preferred. These can be used alone or in combination of two or more.

[0084] The amount of the volatile additive added is usually 1 part by mass or more, preferably 5 parts by mass or more, more preferably 10 parts by mass or more, even more preferably 20 parts by mass or more, and particularly preferably 30 parts by mass or more, and usually 200 parts by mass or less, preferably 150 parts by mass or less, more preferably 130 parts by mass or less, even more preferably 110 parts by mass or less, and particularly preferably 100 parts by mass or less, when the amount is within the above range, a good porosity can be ensured as a composite material.

[0085] In the mixing step, it is preferable to add and mix a solvent in addition to the thermoplastic resin, the filler, and the volatile additive. The solvent has the function of making the precursor composition into a paste and enabling it to be uniformly dispersed. Examples of the solvent include water, and lower alcohols such as methanol, ethanol, isopropanol, and butanol. These can be used alone or in combination of two or more kinds.

[0086] The molding step is a step of molding the precursor composition to obtain a rollable object, and examples of the molding machine used in the molding step include an FT die (fishtail extrusion die), a press machine, an extrusion molding machine, a calendar roll, etc. In particular, an FT die is preferred.

[0087] The rolling process is a process in which the rolled object is rolled to obtain a composite material, and is preferably "multi-stage rolling" in which the obtained rolled object is stacked and rolled as the rolled object multiple times, and is particularly preferably "multi-stage different direction rolling" in which the rolled object is rolled in a direction different from the previous rolling direction. As an example of multi-stage different direction rolling, the rolled object is stacked so that they face the same rolling direction to obtain the rolled object, and the rolling direction of the rolled object is rotated 90° from the previous rolling direction to perform rolling repeatedly.

[0088] The number of layers of the rolled product in the multi-stage rolling is usually 2 or more, preferably 3 or more, more preferably 4 or more, even more preferably 10 or more, and particularly preferably 30 or more, and is usually 2000 or less, preferably 1000 or less, more preferably 700 or less, even more preferably 500 or less, and particularly preferably 300 or less.

[0089] The rolling ratio in the rolling step is usually 10 or more, preferably 20 or more, more preferably 40 or more, even more preferably 50 or more, and particularly preferably 100 or more, and is usually 20,000 or less, preferably 15,000 or less, more preferably 10,000 or less, even more preferably 5,000 or less, and particularly preferably 3,000 or less.

[0090] The apparatus used in the rolling step includes a press, an extruder, a rolling roll (for example, a calender roll), and the like.

[0091] The method for producing a composite material or a substrate may include other steps, specifically the following steps: An additive removal step of removing the volatile additive from the rolled product (hereinafter, may be abbreviated as "additive removal step"). A hot compression process for hot compressing the rolled product (hereinafter, sometimes abbreviated as "hot compression process"). A resin layer forming step of forming a resin layer containing a thermoplastic resin on one or both sides of the composite material (hereinafter, sometimes abbreviated as "resin layer forming step"). A conductor layer forming step of forming a conductor layer on one or both sides of the composite material (hereinafter, sometimes abbreviated as "conductor layer forming step"). A patterning process for patterning the conductor layer (hereinafter, sometimes abbreviated as "patterning process"). The "additive removing step", "heat compression step", "resin layer forming step", "conductor layer forming step", "patterning step", etc. will be described in detail below.

[0092] The additive removing step is a step of removing the volatile additive from the rolled product, and typically includes a method of heating the rolled product in a heating furnace that can be used for drying. The heating conditions can be appropriately selected depending on the boiling point of the volatile additive, etc.

[0093] The hot compression step is a step of hot compressing the rolled product, and typically includes a method of hot compressing using a press, etc. Hot compression conditions can be appropriately selected, but it is preferable to apply pressure uniformly in the plane of the rolled product.

[0094] The resin layer forming step is a step of forming a resin containing a thermoplastic resin on one or both sides of the composite material, and the resin layer can be formed by a method of attaching a resin film containing a thermoplastic resin to the composite material by heating and pressurizing it using a press machine, etc. By heating and pressurizing the resin film containing a thermoplastic resin, the thermoplastic resin permeates the composite material, effectively suppressing peeling of the conductor layer, etc., and ensuring a good relative dielectric constant, etc., for the composite material. The thickness of the resin film containing a thermoplastic resin is usually 0.050 μm or more, preferably 0.10 μm or more, more preferably 0.40 μm or more, even more preferably 1.0 μm or more, and particularly preferably 1.5 μm or more, and is usually 30 μm or less, preferably 20 μm or less, more preferably 10 μm or less, even more preferably 8.0 μm or less, particularly preferably 6.0 μm or less, and most preferably 5.0 μm or less.

[0095] The pressure in the resin layer forming step is usually 0.01 MPa or more, preferably 0.10 MPa or more, more preferably 0.50 MPa or more, even more preferably 0.80 MPa or more, and particularly preferably 1.00 MPa or more, and is usually 50 MPa or less, preferably 40 MPa or less, more preferably 30 MPa or less, even more preferably 20 MPa or less, and particularly preferably 10 MPa or less. Within the above range, peeling of the conductor layer and the like can be effectively suppressed, and a good relative dielectric constant and the like of the composite material can be ensured.

[0096] The temperature in the resin layer formation step is usually 250° C. or higher, preferably 280° C. or higher, more preferably 300° C. or higher, even more preferably 320° C. or higher, and particularly preferably 340° C. or higher, and usually 500° C. or lower, preferably 480° C. or lower, more preferably 460° C. or lower, even more preferably 440° C. or lower, and particularly preferably 420° C. or lower. Within the above range, peeling of the conductor layer and the like can be effectively suppressed, and a good relative dielectric constant and the like of the composite material can be ensured.

[0097] The heating and pressing time in the resin layer forming step is usually 1 second or more, preferably 30 seconds or more, more preferably 1 minute or more, even more preferably 2 minutes or more, and particularly preferably 3 minutes or more, and is usually 180 minutes or less, preferably 120 minutes or less, more preferably 60 minutes or less, even more preferably 30 minutes or less, and particularly preferably 20 minutes or less. Within the above range, peeling of the conductor layer and the like can be effectively suppressed, and a good relative dielectric constant and the like of the composite material can be ensured.

[0098] Examples of the device used in the resin layer forming step include a press machine, a heat roll laminator, and a belt press machine.

[0099] The conductor layer forming step is a step of forming a conductor layer on one or both sides of the composite material. Examples of the method for forming the conductor layer include sputtering, plating, pressure bonding of metal foil, lamination, and the like.

[0100] The patterning step is a step of patterning the conductor layer, and examples of the patterning method include an additive method using a photoresist or the like, and a subtractive method using etching.

[0101] When the resin of the composite material is a thermosetting resin, a manufacturing method of the composite material including the following filler preparation step, mixing step, molding step, and curing step (hereinafter sometimes abbreviated as "manufacturing method of the composite material") is preferred. A filler preparation process for preparing a filler (hereinafter, may be abbreviated as "filler preparation process"). A mixing step of mixing the thermosetting resin, the filler, and the curing accelerator to obtain a precursor composition (hereinafter, may be abbreviated as "mixing step"). A molding process (hereinafter, sometimes abbreviated as "molding process") in which the precursor composition is molded to obtain a plate-shaped pre-cured composite material. A hardening step of hardening the molded body to obtain a composite material (hereinafter, may be abbreviated as "hardening step"). A conductor layer forming step of forming a conductor layer on one or both sides of the composite material (hereinafter, sometimes abbreviated as "conductor layer forming step"). A patterning process for patterning the conductor layer (hereinafter, sometimes abbreviated as "patterning process"). The "filler preparation step," "mixing step," "molding step," "curing step," "conductor layer formation step," "patterning step," and other steps will be described in detail below when the resin of the composite material is a thermosetting resin.

[0102] The filler preparation step is a step of preparing a filler, and the filler (including inorganic fine particle aggregates) may be obtained or produced by the process itself. The median diameter d50 of the granulated filler (secondary particles or later particles) to be prepared is usually 0.1 μm or more, preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 3 μm or more, and usually 500 μm or less, preferably 200 μm or less, more preferably 100 μm or less, even more preferably 50 μm or less, and particularly preferably 20 μm or less. The particle diameter of the granulated filler can be determined by a method conforming to Japanese Industrial Standard JIS Z 8825:2001. In addition, the filler is preferably surface-modified with the above-mentioned surface modifier.

[0103] In the mixing step, the filler is added to the heated thermosetting resin, and the curing accelerator is added after stirring. The heating temperature of the thermosetting resin is usually 40° C. or higher, preferably 50° C. or higher, more preferably 60° C. or higher, and even more preferably 70° C. or higher, and usually 120° C. or lower, preferably 110° C. or lower, more preferably 100° C. or lower, even more preferably 95° C. or lower, and particularly preferably 90° C. or lower. When the filler is added to the thermosetting resin, it is desirable to gradually drop the filler while stirring with a stirrer or the like, and the rotation speed (circumferential speed) is usually 0.2 m / sec or higher, preferably 0.5 m / sec or higher, more preferably 1 m / sec or higher, and even more preferably 1.5 m / sec or higher, and usually 30 m / sec or lower, preferably 25 m / sec or lower, more preferably 20 m / sec or lower, even more preferably 15 m / sec or lower, and particularly preferably 10 m / sec or lower. The stirring time is usually 10 minutes or more, preferably 30 minutes or more, more preferably 45 minutes or more, and even more preferably 60 minutes or more, and usually 240 minutes or less, preferably 210 minutes or less, more preferably 180 minutes or less, even more preferably 150 minutes or less, and particularly preferably 120 minutes or less. Within the above range, it becomes easier to uniformly disperse the resin and the filler, and it becomes easier to keep the standard deviation of the density when the composite material is divided into a plurality of regions low. When gradually adding the curing accelerator to the mixture of the thermosetting resin and the filler, it is desirable to gradually drop it while stirring with a stirrer or the like, and the rotation speed (circumferential speed) is usually 0.2 m / sec or more, preferably 0.5 m / sec or more, more preferably 1 m / sec or more, and even more preferably 1.5 m / sec or more, and usually 30 m / sec or less, preferably 25 m / sec or less, more preferably 20 m / sec or less, even more preferably 15 m / sec or less, and particularly preferably 10 m / sec or less. The stirring time is usually 5 minutes or more, preferably 10 minutes or more, more preferably 15 minutes or more, and even more preferably 20 minutes or more, and usually 120 minutes or less, preferably 60 minutes or less, more preferably 50 minutes or less, even more preferably 40 minutes or less, and particularly preferably 30 minutes or less.

[0104] The forming process is a process of forming the precursor composition into a sheet on one or both sides of a Cu foil, and the forming method is not particularly limited as long as the desired thickness and shape can be obtained. Typical coating methods include slot die coating, gravure coating, bar coating, and impregnation coating, but by adding a method for reducing the unevenness of the surface of the molded product, such as a doctor blade, to bar coating or a typical coating method, the standard deviation of the density when the composite material is divided into multiple regions can be easily suppressed.

[0105] The curing step is a step of curing the precursor composition molded on one or both sides of the Cu foil. As described above, the chemical reaction of the (curing accelerator) is usually accelerated by heat or ultraviolet light, so the curing method and conditions can be selected depending on the type of thermosetting resin and curing accelerator selected. In the case of the ultraviolet curing type, the curing reaction can be accelerated by annealing with heat after irradiation with ultraviolet light. In the case of the thermosetting type, the curing can be accelerated only by annealing, excluding the ultraviolet irradiation step. In the annealing treatment, the treatment method is not particularly limited as long as heat is applied to the precursor composition, but in order to reduce the surface unevenness of the composite, it is preferable to apply uniform pressure within the surface using a hot press.

[0106] The conductor layer forming step is a step of forming a conductor layer on one or both sides of the composite material. Examples of the method for forming the conductor layer include sputtering, plating, pressure bonding of metal foil, lamination, and the like.

[0107] The patterning step is a step of patterning the conductor layer, and examples of the patterning method include an additive method using a photoresist or the like, and a subtractive method using etching. EXAMPLES

[0108] The present invention will be described in more detail below with reference to examples, but the examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited to the specific examples shown below.

[0109] <Example 1> The resin used was polytetrafluoroethylene (hereinafter sometimes abbreviated as "PTFE"), a fluorine-based resin, and the filler was hydrophobic fumed silica (hereinafter sometimes abbreviated as "fumed silica"). As a pretreatment of the resin, PTFE (manufactured by Daikin, product number "Polyflon PTFE F-104", average particle size: 768 μm) and dry ice pellets (1 × 1 × 3 mm) were adjusted to a mass ratio of 1:3, and pulverized in a mechanical continuous pulverizing mill (circumferential speed: 100 m / sec, time: 1 second) to produce PTFE powder with an average particle size of 114 μm (the average particle size is a value determined by a method conforming to the Japanese Industrial Standard JIS Z 8825:2001). Fumed silica (manufactured by Nippon Aerosil, product number "NY50", BET: specific surface area 30 m 2 The mixture was mixed with pretreated PTFE and fumed silica (weight ratio: 40:60 (mass ratio)) in a high-speed fluid mixer (peripheral speed: 18 m / sec, time: 10 minutes). Dodecane, a volatile additive, was added to this mixture in an amount of 40 mass% (total), and mixed in a paddle mixer (peripheral speed: 9 m / sec, temperature: 24°C, time: 1 minute). The obtained paste was extruded in a fishtail extrusion die and a rectangular mother sheet (sheet-shaped molded product) with a sheet thickness of 2 mm, width of 40 mm, and arbitrary length was obtained in a molding machine. Note that multiple mother sheets were produced.

[0110] Two mother sheets were stacked with the rolling direction aligned, and the sheet surfaces were rolled in the previous rolling direction while keeping them parallel to each other to produce a second rolled laminate sheet. A plurality of second rolled laminate sheets were produced. Furthermore, four second rolled laminate sheets were stacked together to produce a third rolled laminate sheet. In this way, the process of stacking and rolling the sheets was repeated a total of four times, counting from the stacking and rolling of the mother sheets, and then the gap between the rolls was narrowed by 0.5 mm each time and rolled multiple times to obtain a sheet with a thickness of about 160 μm (128 layers in total). Next, the obtained rolled laminate sheet was heated at 150 ° C for 20 minutes to remove the volatile additives, and the composite material of Example 1 was produced.

[0111] Next, Fluon (registered trademark) PTFE dispersion AD939E (manufactured by Asahi Glass Co., Ltd., solid content: 60 mass%, average particle size: 39 μm) was applied by dip coating to one side of the polyimide carrier so that the wet thickness (undried coating thickness) was 4 μm, and heated at 150 ° C for 5 minutes and at 380 ° C for 5 minutes to produce a resin film that would become a resin layer. A Cu foil (manufactured by JX Metals Co., Ltd., product number "BHFX-HS-92F", thickness: 18 μm, maximum height Rz: 0.75 μm) that would become a conductor layer was prepared, and the resin film and Cu foil were laminated, and pressed with a press machine at a pressure of 6 MPa, a temperature of 360 ° C, and for 10 minutes to produce a resin conductor sheet. This resin conductor sheet and the above-mentioned composite material were laminated, and pressure-molded at 360 ° C for 10 minutes at 6 MPa to obtain a copper layer-attached substrate using the composite material of Example 1. The final thickness (substrate (composite material) + copper layer (conductor layer)) was approximately 162 μm.

[0112] <Example 2> Fluon® PTFE dispersion AD939E (Asahi Glass Co., Ltd., solid content: 60% by mass, average particle size: 39 μm) and fumed silica (Nippon Aerosil Co., Ltd., product number "NY50", BET specific surface area: 30 m 2The mixture was adjusted to a ratio of PTFE and fumed silica of 40:60 (mass ratio), and then charged into a methanol aqueous solution (methanol concentration: 60 mass%) in an amount 10 times the mass of the fumed silica, and dispersed with a homogenizer (peripheral speed: 30 m / sec, temperature: 25°C, time: 1 minute). The gel-like PTFE-fumed silica dispersion obtained was dried at 150°C for 3 hours, and the volatile additive dodecane was added to the obtained powder in the same manner as in Example 1, and the composite material of Example 2 was obtained by rolling and pressing. Next, a resin conductor sheet was laminated in the same manner as in Example 1, and a substrate with a copper layer was obtained using the composite material of Example 2. The final thickness (substrate (composite material) + copper layer (conductor layer)) was about 169 μm.

[0113] <Example 3> As a pretreatment of the resin, PTFE (manufactured by Daikin, product number "Polyflon PTFE F-104", average particle size: 768 μm) and dry ice pellets (1 × 1 × 3 mm) were adjusted to a mass ratio of 3:1, and pulverized in a mechanical continuous pulverizing mill (circumferential speed: 100 m / sec, time: 1 second) to produce PTFE powder with an average particle size of 249 μm. Fumed silica (manufactured by Nippon Aerosil, product number "NY50", BET specific surface area: 30 m 2 The pretreated PTFE and fumed silica (weight ratio: 40:60 (mass ratio), apparent specific gravity: 60 g / L, average particle size of primary particles: 30 nm, average particle size of granulated material: 5 μm) were adjusted to 40:60 (mass ratio) and mixed in a high-speed fluid mixer (circumferential speed: 18 m / sec, time: 10 minutes). Dodecane, a volatile additive, was added to the obtained mixed powder in the same manner as in Example 1, and the mixture was rolled and pressed to obtain a composite material of Example 3. Next, a resin conductor sheet was laminated in the same manner as in Example 1 to obtain a substrate with a copper layer using the composite material of Example 3. The final thickness (substrate (composite material) + copper layer (conductor layer)) was about 169 μm.

[0114] <Example 4> As a pretreatment of the resin, a PTFE powder having an average particle size of 114 μm was prepared in the same manner as in Example 1. Fumed silica (manufactured by Nippon Aerosil Co., Ltd., product number "NY50", BET specific surface area: 30 m 2 / g, apparent specific gravity: 60g / L, average particle size of primary particles: 30nm, average particle size of granulated material: 5μm) and fused silica (manufactured by Denka, product number "SFP-130MC", BET specific surface area: 6m 2 The mixture was adjusted to a mass ratio of 45:55 (mass ratio) and mixed in a high-speed fluid mixer (circumferential speed: 18 m / sec, time: 1 minute) to obtain a mixed powder (BET specific surface area: 18 m 2 / g, apparent specific gravity: 130g / L, average particle size of primary particles: 320nm, average particle size of granulated material: 8μm) was produced. The mixed powder and the pretreated PTFE powder were adjusted to 62:38, and mixed in a high-speed fluid mixer (circumferential speed: 18m / sec, time: 1 minute). Dodecane, a volatile additive, was added to this mixture so as to be 40 mass% (total), and mixed in a paddle mixer (circumferential speed: 9m / sec, temperature: 24°C, time: 1 minute). The obtained paste was extruded in a fishtail extrusion die and a rectangular mother sheet (sheet-shaped molded body) with a sheet thickness of 2mm, width of 40mm, and arbitrary length was obtained in a molding machine. Note that multiple mother sheets were produced. As a subsequent process, a substrate with a copper layer was produced in the same manner as in Example 1. The final thickness (substrate (composite material) + copper layer (conductor layer)) was about 163μm.

[0115] <Example 5> Liquid epoxy resin (Mitsubishi Chemical Corporation, jER828) and fumed silica (Nippon Aerosil Co., Ltd., product number "NY50", BET specific surface area: 30 m 2 / g, apparent specific gravity: 60g / L, average particle size of primary particles: 30nm, average particle size of granulated material: 5μm) were weighed out to be 80:20 (mass ratio), and the liquid epoxy resin was heated to 80 ° C. and stirred with a small dispersing device (Primix Corporation, Lavlution, Homo Disper 2.5 type, peripheral speed: 1.5m / sec, time: 90 minutes), and fumed silica was gradually added. After the addition of fumed silica, a curing accelerator (San-Apro Corporation, CPI-101A) and the liquid epoxy resin were added so that the ratio was 2:100 (mass ratio), and the mixture was stirred with a small dispersing device (Primix Corporation, Lavlution, Homo Disper 2.5 type, peripheral speed: 1.5m / sec, time: 30 minutes). The conductor layer was formed on Cu foil (JX Metals, product number "BHFX-HS-92F", thickness 18 μm, maximum height Rz: 0.75 μm) using an applicator (Imoto Manufacturing, simple applicator 3400) with an applicator gap adjusted to 0.5 mm, and then coated with a UV irradiation device (HOYA CANDEO OPTRONICS, H-300AH4-V1-NI1, emission wavelength 365 nm, exposure dose 1000 mJ / cm). 2 ), then annealed by heat pressing at 140°C, 0.1 MPa, for 60 minutes. On the side opposite the Cu foil, NiCr 5nm and Cu 200nm were formed by sputtering, and then an 18μm Cu layer was formed by electrolytic plating to produce a substrate with a copper layer. The final thickness (substrate (composite material) + copper layer (conductor layer)) was approximately 153μm.

[0116] <Comparative Example 1> The fluororesin used was polytetrafluoroethylene (manufactured by Daikin Corporation, product number "Polyflon PTFE F-104", average particle size 768 μm) and the filler was hydrophobic fumed silica (manufactured by Nippon Aerosil Co., Ltd., product number "NY50", BET specific surface area 30 m 2 / g, apparent specific gravity 60g / L, average particle size of primary particles 30nm, average particle size of granulated material: 5μm) were mixed in a high-speed fluid mixer (circumferential speed: 14m / sec, time: 10 minutes) so that the fumed silica and pulverized PTFE were in a ratio of 60:40 (mass ratio). Dodecane, a volatile additive, was added to the obtained mixed powder in the same manner as in Example 1, and the mixture was rolled and pressed to obtain a composite material of Comparative Example 1. Next, a resin conductor sheet was laminated in the same manner as in Example 1 to obtain a substrate with a copper layer using the composite material of Comparative Example 1. The final thickness (substrate (composite material) + copper layer (conductor layer)) was about 166μm.

[0117] <Comparative Example 2> A commercially available circuit board material (manufactured by ROGERS, product number "RO3003", thickness: 129 μm, thickness of substrate (composite material) + copper layer (conductor layer): 167 μm) was used as the composite material of Comparative Example 2. Note that, as described in U.S. Patent No. 5,922,453, the composite material of Comparative Example 2 contains silica and titania, and it was confirmed that the silica content was 53.5 vol%, the titania content was 2 vol%, and the PTFE content was 44.5 vol%.

[0118] <Comparative Example 3> A commercially available circuit board material (manufactured by PANASONIC Corporation, product number "R-1766", thickness: 224 μm, thickness of board (composite material) + copper layer (conductor layer): 260 μm) was used as the composite material of Comparative Example 3. It was confirmed that the composite material of Comparative Example 3 was composed of glass cloth and a cured epoxy resin.

[0119] <Measurement of relative dielectric constant> The complex permittivity was measured at a measurement frequency of 10 GHz by the cavity resonator perturbation method (a method conforming to IEC 62562), and its real part (εr') was taken as the relative permittivity. Using a relative permittivity measuring device (Agilent Technologies, model number "Network Analyzer N5230C" and Kanto Electronics Application Development, model number "Cavity Resonator 10 GHz"), 15 rectangular evaluation samples (sample size width 2 mm × length 50 mm) were cut out from each sheet (300 mm × 480 mm), and the average value, standard deviation, and variation value of the relative permittivity [values ​​calculated by substituting the maximum value, minimum value, and average value of the relative permittivity value group into the formula ((maximum value - minimum value) / average value × 100)] were calculated. The results are shown in Tables 1 and 2.

[0120] <Density measurement> The 15 rectangular evaluation samples (width 2 mm × length 50 mm) used in the above-mentioned "Measurement of relative dielectric constant" were cut out by 20 mm from the tip of the end inserted into the cavity resonator, and the dimensions in the width and length directions were measured using a projector (Mitutoyo Corporation, model number "PJ-H30", set magnification 10 times). The end of the evaluation sample can be easily determined by measuring it by the transmission method. The thickness of the evaluation sample was measured using a dial gauge (Mitutoyo Corporation, 543 series ABS solar type digital indicator ID-SS), and the mass of the 15 evaluation samples was measured using an electronic balance (Shimadzu Corporation, AUW220D, measurement environment temperature 25 °C, minimum display unit 0.01 mg), and the density was calculated by substituting it into the following formula. The results are shown in Tables 1 and 2. Density [g / cm 3 ] = mass of sample [g] ÷ (surface area of ​​sample [cm 3 ]×thickness [cm])

[0121] <Thickness of composite material> The thickness of the composite material was determined as the result of thickness measurement using a dial gauge (Mitutoyo Corporation, 543 series ABS solar type digital indicator ID-SS) as described above in "density measurement."

[0122] <Measurement of filler / reinforcement content> The evaluation sample evaluated in the above-mentioned "Measurement of Density" was subjected to TG-DTA (manufactured by BRUKER, 2000SA) under a nitrogen atmosphere with a heating rate of 20 °C / min up to 900 °C, and the mass loss was evaluated. The filler content was calculated by substituting the mass loss, the mass of the resin, and the mass of the remaining components as the filler mass into the following formula. The results are shown in Table 1 and Table 2. Filler content [mass%] = (mass of remaining components [g] ÷ initial mass [g]) × 100 Note that the measurement method of the reinforcing material content can also be applied mutatis mutandis to the above measurement method of the filler content. When both the filler and the reinforcing material are included, the content calculated by the above formula is the content of the filler and the reinforcing material.

[0123] <Calculation of Porosity> The bulk density of the evaluation sample obtained from the above-mentioned "Measurement of Density", the true density calculated from the filler content calculated in the above-mentioned "Measurement of Filler Content", and the density of air were substituted into the following formula to calculate the porosity. As the density of silica, 2.2 [g / cm 3 , as the density of PTFE, 2.1 [g / cm 3 , as the density of titania, 4.0 [g / cm 3 , as the density of glass cloth, 2.4 [g / cm 3 , and as the density of epoxy resin, 1.13 [g / cm 3 were used for the calculation. The results are shown in Table 1 and Table 2. Porosity [volume%] = (bulk density [g / cm 3 - true density [g / cm 3 ) ÷ (bulk density [g / cm 3 - density of air [g / cm 3 ) × 100 True density [g / cm 3 = mass% of filler × filler density [g / cm 3 + mass% of resin × resin density [g / cm 3

[0124] <Measurement of Coefficient of Thermal Expansion in Z-Axis> The thermal expansion coefficient in the Z-axis direction was evaluated by laser interferometry (ULVAC-RIKO Laser Thermal Dilatometer LIX-1, measurement temperature range: -50 to 200°C, heating rate: 2°C / min, atmosphere: He, load: 17g). The thermal expansion coefficient was calculated from a formula based on the Japanese Industrial Standard JIS R3251-1990, and the average value of the thermal expansion coefficient from -50°C to 200°C was used. The results are shown in Tables 1 and 2.

[0125] FIG. 5 shows the ring resonator pattern, and FIG. 6 shows the pattern of the contact portion with the measurement terminal.

[0126] <Formation of ring resonator> A ring resonator pattern was formed by a subtractive method on each of the copper layer-attached substrate using the composite material of Example 1 and the copper layer-attached substrate using the composite material of Comparative Example 2 (see FIG. 5). The plating thickness was set to 17 μm, and 15 ring resonator patterns were evenly formed on the sample (300 mm×480 mm), and a TRL (Through-Reflect-Line) standard was formed in the center. The circuit processing was performed with a processing accuracy in accordance with the Japanese Industrial Standard JIS C 5014:1994. The design value of the ring resonator was determined by substituting the relative dielectric constant of the sample, the thickness of the composite material, and the thickness of the metal layer into the following formula so that a resonant frequency peak was obtained at 60 GHz. The radius of the ring resonator refers to the distance from the center of the ring resonator, which has a width of 0.2 mm, to the center of the line width of the ring resonator, and the length of the microstrip line is 10 mm. The width of the microstrip line was determined by TDR (Time Domain Reflectometry) measurement at 50 Ω termination using a method in accordance with Japanese Industrial Standard JIS C 5402-23-4:2006. The results are shown in Tables 1 and 2. Radius of ring resonator [mm] = 3.14 × 10 8 [m / sec]÷(2×π×60[GHz]×√effective dielectric constant) Effective Permittivity = (dielectric constant + 1) ÷ 2 + ((dielectric constant - 1) ÷ 2) × (1 ÷ √(1 + 12 × composite material thickness [mm] ÷ pattern line width [mm]))

[0127] <Resonant frequency measurement> The resonance frequency was measured by forming 15 ring resonator patterns evenly on a sheet (300 mm x 480 mm) and measuring the resonance points of all 15 patterns using a network analyzer (Keysight Technologies, N5227A PNA Microwave Network Analyzer, frequency: 0 to 67 GHz) and an evaluation probe (Cascade Microtech, ACP65-GSG 150, pad pitch: 150 μm). The contact between the evaluation probe and the evaluation sample was calibrated using a TRL standard device, and the S-parameters (S 21 ) was measured. The resonant frequency peak was determined by a method conforming to IPC-TM-650 2.5.5.5. The difference between the maximum and minimum values ​​of the measured resonant frequency peak was adopted as the resonant frequency variation. The results are shown in Tables 1 and 2. Note that the "actual measurement value" in Tables 1 and 2 means the actual resonant frequency variation value determined by the above-mentioned method, and the "theoretical value" in Tables 1 and 2 means the theoretical value calculated from the relationship between the standard deviation of density and the resonant frequency variation (actual measurement value) of Example 1 and Comparative Example 2 (the plots of Example 1 and Comparative Example 2 are connected by a straight line, and the standard deviation value of density is plotted on the straight line to calculate the theoretical value of the resonant frequency variation). Resonant frequency variation [GHz] = Maximum value of resonant frequency peak [GHz] - Minimum value of resonant frequency peak [GHz]

[0128] [Table 1]

[0129] [Table 2]

[0130] As is clear from the results shown in Tables 1 and 2, the commercially available circuit board materials of Comparative Example 2 and Comparative Example 3 have a standard deviation of density larger than 0.027, and the variation in resonance frequency is also large. The composite material of Comparative Example 2 has a tendency to have a large standard deviation of density, even though the standard deviation of the filler content is low. The reason for this is that the density of titania is very high compared to silica and PTFE contained in the composite material, and the uneven distribution of titania is likely to cause unevenness in the density distribution. The same is true for the composite material of Comparative Example 3, and it is thought to be due to the uneven distribution of pores and the like caused by the large content of reinforcing material. [Industrial Applicability]

[0131] The composite material according to one embodiment of the present invention can be used as a circuit board for mobile phones, computers, etc., a substrate for a microstrip patch antenna for a millimeter wave radar, etc.

[0132] In the above embodiment, specific embodiments of the present invention are shown, but the above embodiment is merely illustrative and should not be interpreted as being limiting. Various modifications that are obvious to those skilled in the art are intended to be within the scope of the present invention. [Explanation of symbols]

[0133] 1 Microstrip patch antenna 2. Board 3 Antenna elements (patches) 4. Radio Waves 5. An area of ​​the board 6 Resonant Ring Pattern 7 Microstrip Line 8 Probe Contact Pattern 9 Through Hole 10 Signal Terminal Pad 11 Microstrip line connection pattern 12 Ground terminal pad

Claims

1. A method for manufacturing a plate-shaped composite material including a resin and at least one selected from the group consisting of a filler and a reinforcing material, The density (unit: g / cm 3 ) of each region when divided into a plurality of regions, and the standard deviation of the density calculated from the group of density values collected is 0.027 or less. A method for manufacturing a plate-shaped composite material, which comprises a step of dispersing at least one selected from the group consisting of a filler and a reinforcing material in the resin during mixing.

2. The method for manufacturing a plate-shaped composite material according to Claim 1, wherein the variation value of the density calculated by substituting the maximum value, the minimum value, and the average value of the density value group into the formula ((maximum value - minimum value) / average value × 100) is 7.4% or less.

3. The method for manufacturing a plate-shaped composite material according to Claim 1 or 2, wherein the porosity of the plate-shaped composite material is manufactured to be 3 to 90% by volume.

4. Including the filler, The method for manufacturing a plate-shaped composite material according to any one of Claims 1 to 3, wherein the content of the filler is manufactured to be 10 to 90% by mass.

5. Including the filler, The method for manufacturing a plate-shaped composite material according to any one of Claims 1 to 4, wherein the content of the filler is 57% by mass or less, and the standard deviation of the content calculated from the content value group obtained by collecting the content of the filler (unit: % by mass) in each region when divided into a plurality of regions is 0.7 or less.

6. Including the reinforcing material, The method for manufacturing a plate-shaped composite material according to any one of Claims 1 to 5, wherein the content of the reinforcing material is manufactured to be 10 to 90% by mass.

7. The method for manufacturing a plate-shaped composite material according to any one of Claims 1 to 6, wherein the standard deviation of the relative permittivity calculated from the relative permittivity value group obtained by collecting the relative permittivity of each region when divided into a plurality of regions is 0.02 or less.

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