Curable resin composition, cured product, laminate, and antenna module

Abstract

To provide a curable resin composition, a cured product, a laminate, and an antenna module for an antenna substrate, which achieve low dielectric constant (Dk) and low dielectric loss tangent (Df), with reduced frequency dependence.SOLUTION: A curable resin composition for an antenna substrate, comprising a maleimide resin.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a curable resin composition, a cured product, a laminate, and an antenna module. [Background technology]

[0002] In recent years, the expansion of 5G (5th Generation Mobile Communication System) and research and development of post-5G mobile communication systems have progressed. To achieve the high speed, large capacity, low latency, and simultaneous multiple connections that characterize these services, frequency bands have been expanded and opened up, including the Sub6 band (3.7 GHz and 4.5 GHz), millimeter wave band (28 GHz), and terahertz wave band (150 GHz and 300 GHz), which are higher frequency bands than 4G and LTE. This has enabled communications using wider bands than ever before. To achieve these communications, a large number of small cells containing radio units (RUs) must be deployed. Furthermore, the antenna modules built into RUs must be highly functional, capable of processing signals in multiple frequency bands and enabling beamforming through phased array antennas. Antenna module configurations such as AiB (Antenna in Board) and AiP (Antenna in Package) have been proposed. For multi-band support, multiple units are combined to form an antenna device. In order to suppress the attenuation of high-frequency signals, the substrate material of the antenna module is required to have low relative permittivity (Dk) and dielectric loss tangent (Df). Known substrate materials for conventional antenna modules include polytetrafluoroethylene (PTFE) (Patent Documents 1 and 2), polyimide (PI), and liquid crystal polymer (LCP). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-086748 [Patent Document 2] Japanese Patent Publication No. 2022-021619 Summary of the Invention [Problem to be solved by the invention]

[0004] The inventors have examined various materials known to be used for antenna substrates and found that antenna modules using PI or LCP have the property (frequency dependency) that the relative permittivity (Dk) and dielectric loss tangent (Df) change depending on the frequency of the signals being transmitted and received.

[0005] If the substrate material of the antenna module is frequency-dependent, it becomes necessary to design the antenna module by optimizing the thickness of each layer for each frequency of the signal to be transmitted and received in order to reduce variations in communication quality. In particular, when manufacturing a multi-band antenna device that is used in multiple frequency bands, it is necessary to prepare and combine several types of antenna modules optimized for each frequency band, which can result in an increased size of the antenna device.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a curable resin composition for antenna substrates, a cured product, a laminate, and an antenna module that have both a low relative dielectric constant (Dk) and a low dielectric loss tangent (Df) and little frequency dependency. [Means for solving the problem]

[0007] In order to solve the above problems, the present disclosure provides the following curable resin composition, cured product, laminate, and antenna module.

[0008] [1] A curable resin composition for an antenna substrate, comprising a maleimide resin. [2] The curable resin composition according to [1] above, wherein the cured product of the curable resin composition has a relative dielectric constant (Dk) of less than 3.0 in the frequency range of 20 GHz to 100 GHz, and the variation of the relative dielectric constant (Dk) of the cured product of the curable resin composition measured by the following method is 0.05 or less. Measurement method for variation in dielectric constant (Dk): The dielectric constant (Dk) of the cured product of the curable resin composition is measured at 10 GHz intervals between 20 GHz and 100 GHz. The maximum and minimum values of the nine measurements obtained are used to determine the variation in the dielectric constant (Dk). Variation in relative permittivity (Dk) = (maximum value of relative permittivity (Dk)) - (minimum value of relative permittivity (Dk)) [3] The dielectric loss tangent (Df) of the cured product of the curable resin composition in the frequency range of 20 GHz to 100 GHz is 3.0 × 10 -3 The curable resin composition according to the above [1] or [2], wherein the dielectric loss tangent (Df) of a cured product of the curable resin composition has a variation of 0.0005 or less as measured by the following method: Measurement method for the variation of dielectric dissipation factor (Df): The dielectric loss tangent (Df) of the cured product of the curable resin composition is measured at 10 GHz intervals between 20 GHz and 100 GHz. The maximum and minimum values of the nine measurements obtained are used to calculate the variation in the dielectric loss tangent (Df) as follows: Variation of dielectric dissipation factor (Df) = (maximum value of dielectric dissipation factor (Df)) - (minimum value of dielectric dissipation factor (Df)) [4] A cured product of the curable resin composition according to any one of [1] to [3] above. [5] A laminate comprising a resin layer containing a cured product of the curable resin composition according to any one of [1] to [3] above. [6] An antenna module comprising: an antenna substrate containing a cured product of the curable resin composition according to any one of [1] to [3] above; and an antenna electrically connected to the antenna substrate. [7] The antenna module according to [6] above, wherein the antenna substrate includes one or more insulating substrate layers, and at least one of the insulating substrate layers includes the cured product. [8] The antenna module described in [6] above, wherein the antenna substrate includes two or more insulating substrate layers and one or more adhesive layers arranged between the insulating substrate layers, and at least one of the insulating substrate layers and the adhesive layers includes the cured product. [9] The antenna module according to any one of the above [6] to [8], further comprising a heat dissipation substrate. [Effects of the Invention]

[0009] According to the present disclosure, it is possible to provide a curable resin composition for antenna substrates, a cured product, a laminate, and an antenna module that have both a low relative permittivity (Dk) and a low dielectric loss tangent (Df) and little frequency dependency. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a cross-sectional view schematically illustrating an embodiment of an antenna module according to the present disclosure. [Figure 2] FIG. 2 is a cross-sectional view schematically showing another embodiment of an antenna module according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, several embodiments of the present disclosure will be described in detail, but the present disclosure is not limited to the following embodiments.

[0012] In this specification, numerical ranges indicated with "to" indicate ranges that include the numerical values before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit of a certain numerical range may be replaced with the upper or lower limit of another numerical range. Furthermore, in numerical ranges described in this specification, the upper or lower limit of that numerical range may be replaced with a value shown in the Examples. When referring to the amount of each component in a composition in this specification, if multiple substances corresponding to each component are present in the composition, the total amount of those multiple substances present in the composition is used unless otherwise specified. "A or B" means that either A or B is present, or both may be present. "Solid content" refers to the non-volatile content of a resin composition, excluding volatile substances (water, solvent, etc.). In other words, "solid content" refers to components other than the solvent that remain without volatilization during drying of the resin composition, as described below, and includes components that are liquid, syrup-like, or waxy at room temperature (25°C). In this specification, for example, "(meth)acrylic acid" means "acrylic acid" and its corresponding "methacrylic acid," and the same applies to other similar terms.

[0013] [Curable resin composition] The curable resin composition for an antenna substrate according to this embodiment contains a maleimide resin (hereinafter also referred to as "component (A)"). The curable resin composition according to this embodiment has a low relative permittivity (Dk) and a low dielectric loss tangent (Df) and exhibits little frequency dependency, making it suitable for producing an antenna substrate.

[0014] The maleimide resin can be obtained, for example, by reacting a tetracarboxylic dianhydride (a1) (hereinafter also referred to as "component (a1)"), an amine (a2) (hereinafter also referred to as "component (a2)"), and maleic anhydride (a3) (hereinafter also referred to as "component (a3)"). Here, the component (a2) may contain dimer diamine. The component (A) can be used alone or in combination of two or more types.

[0015] The tetracarboxylic dianhydride of the component (a1) can be any known polyimide raw material. Examples of the component (a1) include pyromellitic anhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-c]furan-1,3-dione, 4,4'-oxydiphthalic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone ... ,3',4,4'-Benzophenonetetracarboxylic dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, bicyclo[2.2.2]oct-7-ene- 2,3,5,6-Tetracarboxylic dianhydride, bis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylic acid) 1,4-phenylene, 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride, 4,4'-(ethyne-1,2-diyl)diphthalic anhydride, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, dicyclohexyl-3,4,3',4'-tetracarbo Examples of suitable phthalic anhydrides include phthalic dianhydride, 3,4'-oxydiphthalic anhydride, 3,4'-biphthalic anhydride, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride, 5,5'-bis-2-norbornene-5,5',6,6'-tetracarboxylic-5,5',6,6'-dianhydride, and 9,9-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride.Among these, from the viewpoint of availability, pyromellitic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, and 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride are preferred, and from the viewpoint of heat resistance, pyromellitic anhydride is particularly preferred. The component (a1) can be used alone or in combination of two or more.

[0016] Component (a2) may contain dimer diamine. Dimer diamine is a compound derived from dimer acid, which is a dimer of unsaturated fatty acid such as oleic acid, as described in, for example, JP-A-9-12712. By using dimer diamine as component (a2), the dielectric properties of the cured product can be reduced. In this embodiment, any known dimer diamine can be used without particular limitation. The dimer diamine preferably contains at least one of a compound represented by the following general formula (1) and a compound represented by the following general formula (2).

[0017] [ka] [ka]

[0018] In formulas (1) and (2), m, n, p, and q each represent an integer of 1 or greater selected so that m+n=6 to 17 and p+q=8 to 19, and the bond shown by a dashed line represents a carbon-carbon single bond or a carbon-carbon double bond. However, when the bond shown by a dashed line is a carbon-carbon double bond, formulas (1) and (2) have a structure in which the number of hydrogen atoms bonded to each carbon atom constituting the carbon-carbon double bond is reduced by one from the number shown in formulas (1) and (2).

[0019] The dimer diamine may be one represented by the above general formula (2), particularly a compound represented by the following formula (3), from the viewpoints of solubility in organic solvents, heat resistance, heat-resistant adhesion, low viscosity, etc.

[0020] [ka]

[0021] Commercially available dimer diamine products include, for example, PRIAMINE 1075 and PRIAMINE 1074 (both manufactured by Cargill Japan LLC).

[0022] The component (a2) may contain an amine other than dimer diamine (hereinafter also referred to as "second amine"). The second amine is an amine that does not fall under the category of the above-mentioned dimer diamine. The second amine may be a diamine or triamine, or may be a diamine. By using an alicyclic diamine as the second amine, the dielectric constant can be further reduced. By using an aromatic diamine as the second amine, the elastic modulus and Tg of the cured product can be increased, and the CTE can be reduced.

[0023] When the second amine is a diamine, examples of the diamine include 1,3-diaminopropane, norbornanediamine, 4,4'-methylenedianiline, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis[3-fluoro-4-aminophenyl]fluorene, 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, bis(aminomethyl)norbornane, 4,4'-(hexafluoroisopropylidene)dianiline, 3(4),8(9)-bis(aminomethyl)tricyclo[5.2.1.0 2,6]decane, 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), 4,4'-methylenebis(2-methylcyclohexylamine), 1,1-bis(4-aminophenyl)cyclohexane, 2,7-diaminofluorene, 4,4'-ethylenedianiline, 4,4'-methylenebis(2,6-diethylaniline), 4,4'-methylenebis(2-ethyl-6-methylaniline), 2,2-bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(4-aminophenoxy)phenyl]methane, 4,4'-bis(4-aminophenoxy)biphenyl , bis[4-(4-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ketone, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 2,2'-dimethylbiphenyl-4,4'-diamine, (4,4'-diamino)diphenyl ether, (3,3'-diamino)diphenyl ether, paraphenylenediamine, orthophenylenediamine, metaphenylenediamine, 2,2'-dimethylbiphenyl-4,4'-diamine, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, etc. These can be used alone or in combination of two or more.

[0024] When the second amine is a triamine, examples of the triamine include tris(aminomethyl)amine, tris(2-aminoethyl)amine, tris(2-aminopropyl)amine, 2-(aminomethyl)-2-methyl-1,3-propanediamine, trimer triamine, 3,4,4'-triaminodiphenyl ether, 1,2,4-triaminobenzene, 1,3,5-triaminobenzene, 1,2,3-triaminobenzene, 1,3,5-triazine-2,4,6-triamine, 2,4,6-triaminopyrimidine, 1,3,5-tris(4-aminophenyl)benzene, 1,3,5-tris(4-aminophenoxy)benzene, etc. Among these, from the viewpoint of photocurability, aliphatic amines and alicyclic amines are preferred, and norbornanediamine, isophoronediamine, and tris(2-aminoethyl)amine are more preferred. These can be used alone or in combination of two or more.

[0025] The second amine may include one or both of the above-mentioned diamines and triamines, or may include an amine other than a diamine or a triamine.

[0026] In component (a2), the molar ratio of the second amine to the total amount of amines (moles of second amine / (moles of dimer diamine+moles of second amine)) may be 0.70 or less, 0.50 or less, or 0.30 or less. When this ratio is 0.70 or less, the dielectric properties of the cured product can be further reduced.

[0027] When the second amine contains a diamine, the molar ratio of the diamine in the second amine to the total amount of diamine in component (a2) (number of moles of diamine in the second amine / (number of moles of dimer diamine + number of moles of diamine in the second amine)) may be 0.70 or less, 0.50 or less, or 0.30 or less. When this ratio is 0.70 or less, the dielectric properties of the cured product can be further reduced.

[0028] Component (A) can be produced by various known methods. For example, components (a1) and (a2) are first subjected to a polyaddition reaction at about 60 to 120°C, preferably 70 to 90°C, for typically about 0.1 to 2 hours, preferably 0.1 to 1.0 hours. The resulting polyaddition product is then subjected to an imidization reaction, i.e., a dehydration ring-closing reaction, at about 80 to 250°C, preferably 100 to 200°C, for about 0.5 to 30 hours, preferably 0.5 to 10 hours. The product of the dehydration ring-closing reaction is then subjected to a maleimidization reaction, i.e., a dehydration ring-closing reaction, with component (a3) at about 60 to 250°C, preferably 80 to 200°C, for about 0.5 to 30 hours, preferably 0.5 to 10 hours, to obtain the desired component (A).

[0029] In the imidization reaction or maleimidization reaction, various known reaction catalysts, dehydrating agents, and organic solvents can be used.

[0030] Examples of reaction catalysts include aliphatic tertiary amines such as triethylamine, aromatic tertiary amines such as dimethylaniline, heterocyclic tertiary amines such as pyridine, picoline, isoquinoline, and organic acids such as methanesulfonic acid, paratoluenesulfonic acid monohydrate, etc. Examples of dehydrating agents include aliphatic acid anhydrides such as acetic anhydride, and aromatic acid anhydrides such as benzoic anhydride.

[0031] Examples of organic solvents used in the reaction include aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, and pseudocumene; alcoholic solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol; ketone solvents such as acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, cyclopentanone, cyclohexanone, isophorone, and acetophenone; cellosolves such as methyl cellosolve and ethyl cellosolve; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, methyl propionate, butyl formate, and γ-butyrolactone; and ethylene glycol mono-n-butyl ether. Examples of suitable organic solvents include glycol ether solvents such as ethylene glycol mono-iso-butyl ether, ethylene glycol mono-tert-butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-iso-butyl ether, triethylene glycol monoethyl ether, triethylene glycol mono-n-butyl ether, and tetraethylene glycol mono-n-butyl ether; and nitrogen-containing compounds such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide. These organic solvents can be used alone or in combination of two or more. From the viewpoint of solubility, it is preferable to use toluene, xylene, mesitylene, or pseudocumene in combination with methanol or ethanol.

[0032] Component (A) can be purified by various known methods to increase its purity. For example, first, component (A) dissolved in an organic solvent and pure water are placed in a separatory funnel. The separatory funnel is then shaken and allowed to stand. After the aqueous and organic layers separate, the organic layer can be collected to purify component (A).

[0033] An example of the structure of component (A) produced by the above method is shown in general formula (4) below. [ka]

[0034] In general formula (4), each X independently represents a tetravalent organic group, each Y independently represents a divalent organic group, and a represents an integer of 1 or greater. At least one of the multiple Ys represents the divalent organic group derived from the dimer diamine. Furthermore, X and Y may be an aliphatic group, an organic group having an alicyclic structure, or an aromatic ring, and may contain a heteroatom.

[0035] The molecular weight of component (A) can be controlled by the number of moles of component (a1) and component (a2), and the smaller the number of moles of component (a1) is relative to the number of moles of component (a2), the smaller the molecular weight can be. To facilitate the achievement of the effects of the present disclosure, the number of moles of component (a1) per mole of component (a2), i.e., [number of moles of component (a1)] / [number of moles of component (a2)], is generally in the range of about 0.30 to 0.95, preferably 0.50 to 0.85.

[0036] From the viewpoints of solubility in solvents and heat resistance, the molecular weight of component (A) is preferably a weight average molecular weight (Mw) of 3,000 to 40,000, more preferably 4,000 to 30,000, and even more preferably 5,000 to 28,000 or 7,000 to 27,000. A weight average molecular weight of 40,000 or less tends to provide good solubility in organic solvents, while a weight average molecular weight of 3,000 or more tends to provide a sufficient effect of improving heat resistance. Mw can be measured by gel permeation chromatography (GPC) and converted using a calibration curve of standard polystyrene.

[0037] As the maleimide resin, from the viewpoint of low dielectric properties and adhesiveness, the maleimide resin represented by the above general formula (4) is preferred, and in particular, the maleimide resin obtained by reacting dimer diamine as the component (a2) is preferred.

[0038] The component (A) of this embodiment can be a commercially available compound. Specific examples that can be used include SFR-2300MR-T (synthesized from an amine including dimer diamine, a tetracarboxylic dianhydride, and maleic anhydride) manufactured by Resonac Co., Ltd., and BMI-3000 Commercial Grade (synthesized from dimer diamine, pyromellitic anhydride, and maleic anhydride), BMI-1500, BMI-1700, and BMI-5000 manufactured by DESIGNER MOLECULES Inc.

[0039] From the viewpoint of low dielectric properties, the content of the (A) component is preferably more than 50 parts by mass, and may be 55 to 99 parts by mass, 60 to 96 parts by mass, 70 to 92 parts by mass, or 80 to 90 parts by mass, when the total amount of solids in the curable resin composition is 100 parts by mass.

[0040] The curable resin composition of the present embodiment may contain components other than the maleimide resin, such as a polymerization initiator, a curing accelerator, an inorganic filler, a release agent, a flame retardant, an ion trapping agent, an antioxidant, an adhesion promoter, a stress reducing agent, a colorant, and a coupling agent.

[0041] Examples of the polymerization initiator include thermal radical polymerization initiators, organic peroxides, azo compounds, etc. The polymerization initiators may be used alone or in combination of two or more.

[0042] Examples of the curing accelerator include phosphine compounds, compounds having a phosphonium salt, imidazole compounds, etc. The curing accelerators can be used alone or in combination of two or more.

[0043] Inorganic fillers are added to reduce the thermal expansion coefficient of thermosetting resin compositions and improve their moisture resistance. Examples of such inorganic fillers include silicas such as fused silica, crystalline silica, and cristobalite, alumina, silicon nitride, aluminum nitride, boron nitride, titanium oxide, glass fiber, and magnesium oxide. The average particle size and shape of these inorganic fillers can be selected depending on the application. Among these, spherical alumina, spherical fused silica, and glass fiber are preferred.

[0044] Mold release agents are added to improve releasability from a mold. Examples of mold release agents include carnauba wax, rice wax, candelilla wax, polyethylene, polyethylene oxide, polypropylene, montanic acid, montan wax which is an ester compound of montanic acid with saturated alcohol, 2-(2-hydroxyethylamino)ethanol, ethylene glycol, glycerin, etc., stearic acid, stearic acid ester, and stearic acid amide.

[0045] The flame retardant is added to impart flame retardancy. Known flame retardants can be used without any particular limitation. Examples of the flame retardant include phosphazene compounds, silicone compounds, zinc molybdate-supported talc, zinc molybdate-supported zinc oxide, aluminum hydroxide, magnesium hydroxide, and molybdenum oxide.

[0046] The ion trapping agent is added to the liquid resin composition to trap ionic impurities and prevent thermal and moisture-absorbing deterioration. Any known ion trapping agent can be used, and there is no particular limitation. Examples of the ion trapping agent include hydrotalcites, bismuth hydroxide compounds, and rare earth oxides.

[0047] The preparation means, conditions, etc. of the curable resin composition are not particularly limited. For example, a method may be used in which predetermined amounts of various components are thoroughly and uniformly stirred and mixed using a mixer or the like, and then kneaded using a mixing roll, an extruder, a kneader, a roll, an extruder, etc. The kneading method is not particularly limited.

[0048] From the viewpoint of coatability, the viscosity of the curable resin composition according to this embodiment at 25°C may be 400 to 4000 mPa·s, 400 to 3000 mPa·s, or 500 to 2000 mPa·s. The viscosity of the curable resin composition at 25°C can be measured using an E-type viscometer.

[0049] The cured product of the curable resin composition of this embodiment may have a dielectric constant (Dk) of less than 3.0 in the frequency range of 20 GHz to 100 GHz, and the variation in the dielectric constant (Dk) of the cured product of the resin composition measured by the method described below may be 0.05 or less. If the dielectric constant (Dk) of the cured product of the curable resin composition in the frequency range of 20 GHz to 100 GHz and the variation in the dielectric constant (Dk) measured by the method described below are within the above ranges, the resin composition can be more suitably used as a substrate material for an antenna module.

[0050] Measurement method for variation in dielectric constant (Dk): The dielectric constant (Dk) of the cured product of the curable resin composition is measured at 10 GHz intervals between 20 GHz and 100 GHz. The maximum and minimum values of the nine measurements obtained are used to determine the variation in the dielectric constant (Dk). Variation in relative permittivity (Dk) = (maximum value of relative permittivity (Dk)) - (minimum value of relative permittivity (Dk))

[0051] The dielectric constant (Dk) of the cured product of the curable resin composition of this embodiment in the frequency range of 20 GHz to 100 GHz may be 2.8 or less, 2.6 or less, or 2.5 or less from the viewpoint of low transmission loss. Furthermore, the variation in the dielectric constant (Dk) of the cured product of the curable resin composition of this embodiment measured by the above method may be 0.04 or less, 0.03 or less, or 0.02 or less from the viewpoint of improving the quality of the electrical signal.

[0052] The dielectric loss tangent (Df) of the cured product of the curable resin composition of this embodiment in the frequency range of 20 GHz to 100 GHz is 3.0 × 10 -3The dielectric loss tangent (Df) of a cured product of the resin composition may be less than 0.0005, and the variation in the dielectric loss tangent (Df) of the cured product of the resin composition measured by the method described below may be 0.0005 or less. When the dielectric loss tangent (Df) of a cured product of the curable resin composition between 20 GHz and 100 GHz and the variation in the dielectric loss tangent (Df) measured by the method described below are within the above ranges, the resin composition can be more suitably used as a substrate material for an antenna module. Measurement method for the variation of dielectric dissipation factor (Df): The dielectric loss tangent (Df) of the cured product of the curable resin composition is measured at 10 GHz intervals between 20 GHz and 100 GHz. The maximum and minimum values of the nine measurements obtained are used to calculate the variation in the dielectric loss tangent (Df) as follows: Variation of dielectric dissipation factor (Df) = (maximum value of dielectric dissipation factor (Df)) - (minimum value of dielectric dissipation factor (Df))

[0053] The dielectric loss tangent (Df) of the cured product of the curable resin composition of this embodiment in the frequency range of 20 GHz to 100 GHz is 2.8 × 10 -3 Below, 2.6 x 10 -3 or less or 2.5 x 10 -3 From the viewpoint of improving the quality of electrical signals, the variation in the dielectric loss tangent (Df) of the cured product of the curable resin composition of the present embodiment, measured by the above-described method, may be 0.0004 or less or 0.0003 or less.

[0054] The curable resin composition according to the present embodiment can be produced, for example, by the following method. For example, the maleimide resin and the polymerization initiator and / or curing accelerator are mixed, stirred, dissolved, and / or dispersed simultaneously or separately, while optionally being heated, to obtain the curable resin composition. At least one of an inorganic filler, a mold release agent, a flame retardant, and an ion trapping agent may be added and mixed with the curable resin composition.

[0055] There are no particular limitations on the method for producing the composition and the apparatus for performing mixing, stirring, dispersion, etc. Specifically, for example, a mortar and pestle mixer equipped with a stirring and heating device, a two-roll mill, a three-roll mill, a ball mill, a planetary mixer, a mass colloider, or the like can be used, and these apparatuses may be used in appropriate combination.

[0056] [Cured product of curable resin composition and resin layer containing the cured product] The curable resin composition according to the present embodiment can form a resin layer (cured film) containing a cured product of the curable resin composition, which has low relative permittivity (Dk) and dielectric loss tangent (Df) and little frequency dependency. The resin layer can be formed by a conventionally known method. The cured product of the curable resin composition according to the present embodiment may be a cured product cured by heat, a cured product cured by light, or a cured product cured by both heat and light. For example, a resin layer containing a cured product of the curable resin composition according to the present embodiment can be formed by applying the curable resin composition to a substrate using an applicator, drying the composition in a dryer, and then photocuring the composition by ultraviolet (UV) irradiation and / or thermal curing using a nitrogen dryer.

[0057] The curable resin composition according to the present embodiment can be used to fabricate an antenna module including an antenna substrate having a resin layer formed from a cured product of the curable resin composition, and an antenna electrically connected to the antenna substrate, and an antenna device including a combination of a plurality of antenna modules. The resin layer may have via holes.

[0058] From the viewpoint of impedance control, the thickness of the resin layer may be 12 μm or more and 200 μm or less, or 25 μm or more and 100 μm or less.

[0059] [Laminate] The laminate according to the present embodiment includes a resin layer containing a cured product of the curable resin composition. The laminate may further include a resin layer containing a cured product of a curable resin composition other than the curable resin composition, or may further include a layer containing a material other than resin.

[0060] The curable resin composition other than the curable resin composition is not particularly limited as long as it is a curable resin composition that is generally used to form a circuit board, and may be, for example, a resin composition containing at least one resin selected from the group consisting of polyimide resins and epoxy resins.

[0061] Materials other than resin include ceramics, quartz, and glass.

[0062] [Antenna module] The antenna module according to this embodiment includes an antenna substrate containing a cured product of the above-described curable resin composition for the antenna substrate, and an antenna electrically connected to the antenna substrate. In the antenna module according to this embodiment, since the antenna substrate contains a cured product of the above-described curable resin composition for the antenna substrate, the frequency dependency of the substrate material is small, and the antenna module is suitable for antenna modules and antenna devices that are capable of carrying multiple frequency bands.

[0063] [Antenna board] The antenna substrate according to this embodiment may include, for example, one or more insulating substrate layers, and may include a layer made of an insulating material other than the cured product of the curable resin composition according to this embodiment. Examples of insulating materials other than the cured product of the curable resin composition according to this embodiment include liquid crystal polymer (LCP), polytetrafluoroethylene (PTFE), polyphenylene ether (PPE) resin, fluororesin, cycloolefin resin, maleimide resin, polyimide (PI) resin, modified polyimide resin, epoxy resin, polyphenylene sulfide (PPS) resin, quartz, ceramic, sapphire, and magnetic material. When the insulating substrate layer includes the cured product of the curable resin composition according to this embodiment, frequency dependence can be further reduced.

[0064] The number of insulating base material layers is not particularly limited and may be, for example, 1 to 10 layers, 1 to 8 layers, or 1 to 6 layers, or even 10 or more layers. When the antenna substrate includes multiple insulating base material layers, from the viewpoint of reducing transmission loss, it is preferable that the layer of the antenna substrate in contact with the antenna includes an insulating material having low dielectric properties, and more preferably includes a cured product of the above-mentioned curable resin composition for the antenna substrate.

[0065] Examples of insulating materials with low dielectric properties include polytetrafluoroethylene (PTFE), liquid crystal polymer (LCP), polyphenylene ether (PPE) resin, fluororesin, cycloolefin resin, maleimide resin, polyimide (PI) resin, and modified polyimide resin.

[0066] From the viewpoint of impedance control, the thickness of the insulating base material layer may be 12 μm or more and 200 μm or less, or may be 25 μm or more and 100 μm or less.

[0067] The antenna substrate may include a conductor layer composed of an insulating substrate layer and a conductor pattern and / or a build-up layer composed of an insulating substrate layer and a conductor pattern.

[0068] The antenna module according to the present embodiment may include a single antenna or multiple antennas. The antenna module according to the present embodiment may include a single type of antenna or multiple types of antennas.

[0069] The antenna is electrically connected to the antenna substrate via a conductor pattern, etc. The conductor pattern may include, for example, a transmission line such as a microstrip line, a slot line, or a coplanar line, a through hole, a via, etc. Examples of materials for the conductor pattern include copper, aluminum, gold, silver, and alloys thereof.

[0070] The antenna may be an antenna element, an array antenna, a horn antenna, or an antenna of other shape. Examples of antenna elements include a microstrip antenna (patch antenna), a slot antenna, etc. There are no particular limitations on the method of installing the antenna. For example, multiple antenna elements may be arranged in a two-dimensional array on an antenna substrate.

[0071] In the antenna module, the antenna substrate may include one or more insulating substrate layers, and at least one of the insulating substrate layers may include a cured product of the above-described curable resin composition for the antenna substrate. In this case, from the viewpoint of further reducing frequency dependence, it is preferable that the layer including the cured product of the above-described curable resin composition for the antenna substrate is located closer to the antenna. Specifically, it is preferable that the antenna be mounted on the layer including the cured product of the above-described curable resin composition for the antenna substrate.

[0072] When the antenna is mounted in contact with the insulating base material layer of the antenna substrate, from the viewpoint of reducing transmission loss, the insulating base material layer in contact with the antenna is preferably a layer made of an insulating material having low dielectric properties, and more preferably a layer containing a cured product of the above-mentioned curable resin composition for the antenna substrate.

[0073] In the antenna module, the antenna substrate may include two or more insulating substrate layers and one or more adhesive layers disposed between the insulating substrate layers, and at least one of the insulating substrate layers and the adhesive layers may include a cured product of the curable resin composition for the antenna substrate described above. In this case, from the viewpoint of further reducing frequency dependency, it is preferable that the layer containing the cured product of the curable resin composition for the antenna substrate described above be disposed closer to the antenna.

[0074] The adhesive layer may contain a cured product of a general resin composition used in adhesive applications, or may contain a cured product of the curable resin composition for the antenna substrate described above.

[0075] The antenna module according to this embodiment may further include an integrated circuit (IC) that processes high-frequency signals. The integrated circuit may be mounted on the antenna substrate. The integrated circuit is electrically connected to conductor patterns provided on the surface and inside of the antenna substrate via bumps. Examples of the integrated circuit include integrated circuits such as radio frequency integrated circuits (RFICs). The antenna substrate may incorporate components such as an integrated circuit, a multilayer ceramic capacitor, and an inductor.

[0076] The bumps electrically connect the antenna substrate and the integrated circuit, and may be made of a conductor such as solder.

[0077] The antenna module may further include components other than those described above, for example, a heat dissipation substrate.

[0078] FIG. 1 is a cross-sectional view schematically illustrating one embodiment of an antenna module according to the present disclosure. The antenna module 100 includes an antenna substrate 10 containing a cured product of a curable resin composition for an antenna substrate, and multiple antennas (antenna elements) 3a-3d. The antenna substrate 10 also includes insulating base material layers 1a-1d and adhesive layers 2a-2c disposed between the insulating base material layers 1a-1d. An integrated circuit 6 is electrically connected to a conductor pattern 4 provided on the antenna substrate 10 via bumps 5. While FIG. 1 shows adhesive layers, four antennas, and four insulating base material layers, the antenna module according to this embodiment does not necessarily include adhesive layers, and the number of antennas and the number of insulating base material layers including build-up layers are not limited to these numbers.

[0079] Fig. 2 is a cross-sectional view schematically illustrating another embodiment of an antenna module according to the present disclosure. The antenna module 101 includes an antenna substrate 11 containing a cured product of a curable resin composition for the antenna substrate, an antenna 3e, and a heat dissipation substrate 30. At least a portion of the side surface of the antenna substrate 11 is in contact with the antenna 3e. Although not shown in Fig. 2, the antenna substrate 11 and the antenna 3e are electrically connected via a conductor pattern. Although not specifically shown in Fig. 2, the antenna module 101 may also include a conductor pattern, bumps, and an integrated circuit, similar to the antenna module 100 of Fig. 1.

[0080] The heat dissipation substrate 30 is an insulating layer made of a material with high thermal conductivity. Examples of materials for forming the heat dissipation substrate 30 include SiC (silicon carbide), AlN (aluminum nitride), and Si (silicon). The heat dissipation substrate 30 may have via holes.

[0081] The antenna substrate 11 may further include a metal layer. The metal layer is disposed on at least one surface of the antenna substrate 11. Examples of materials for forming the metal layer include Cu plating and Cu paste. [Example]

[0082] The present disclosure will be described in more detail with reference to the following examples, although the present disclosure is not limited to these examples.

[0083] <Synthesis of Maleimide Resin and Preparation of Curable Resin Composition> A 2L pressure-resistant SUS vessel (manufactured by Todoroki Sangyo Co., Ltd.) equipped with a cooling tube, a separation tank, a nitrogen inlet tube, a thermocouple, and a stirrer, capable of carrying out a reaction under pressure while refluxing the solvent, was charged with 111 parts by mass of pyromellitic anhydride (manufactured by Daicel Corporation), 907 parts by mass of toluene (manufactured by Wako Pure Chemical Industries, Ltd.), and 200 parts by mass of methanol (manufactured by Daishin Chemical Co., Ltd.). Next, nitrogen gas was introduced into the vessel to pressurize it to a gauge pressure of 250 kPa, and the temperature was raised to 80 ° C. and maintained at that temperature for 0.5 hours. Subsequently, 368 parts by mass of dimer diamine (trade name "PRIAMINE 1075", manufactured by Cargill Japan LLC) was added dropwise at a rate of 12.3 g / min. After the dropwise addition, the mixture was maintained at 80 ° C. for 0.5 hours, and then 6.5 parts by mass of methanesulfonic acid was added. The reaction mixture was then heated to 160 ° C. while removing the alcohol-based solvent from the reaction solution. After heating, a dehydration ring-closing reaction was carried out at 160°C for 2 hours, and water and alcohol solvents were removed from the reaction solution to obtain a solution containing an intermediate polyimide resin. Subsequently, the obtained solution containing polyimide resin was cooled to 130°C, and 50 parts by mass of maleic anhydride (manufactured by Fuso Chemical Co., Ltd.) was added. The temperature was then raised to 160°C. After heating, a dehydration ring-closing reaction was carried out at 160°C for 4 hours, and water was removed from the reaction solution to obtain a solution containing maleimide resin.

[0084] The resulting maleimide resin solution was placed in a separatory funnel, and 1,200 parts by mass of pure water was added. The separatory funnel was shaken and allowed to stand. After standing, the organic and aqueous layers were separated, and only the organic layer was recovered. The recovered organic layer was placed in a 1-L glass vessel equipped with a condenser, nitrogen inlet tube, thermocouple, stirrer, and vacuum pump, heated to 88-93°C, and the water was removed. The temperature was then raised to 115°C and the solvent was partially removed for 0.5 hours to obtain a curable resin composition (A-1). The weight-average molecular weight (Mw) of the maleimide resin in (A-1) was 17,200, and the solids content of (A-1) was 58.9% by mass.

[0085] Furthermore, 0.589 parts by mass of DCP (manufactured by NOF Corporation, trade name "Perkmyl D") as a polymerization initiator was added to 100 parts by mass of the obtained curable resin composition (A-1) to prepare a curable resin composition (A-2). The solid content of (A-2) was 59.1% by mass.

[0086] The weight average molecular weight (Mw) of the maleimide resin and the solid content of the curable resin compositions (A-1) and (A-2) were determined by the following methods.

[0087] [Weight average molecular weight] The weight-average molecular weight of the maleimide resin was measured by gel permeation chromatography (GPC). A sample prepared by dissolving maleimide resin in tetrahydrofuran (THF) to a concentration of 3% by mass was injected in an amount of 50 μL into columns (one GL-R420 (Hitachi High-Tech Fielding Corporation), one GL-R430 (Hitachi High-Tech Fielding Corporation), and one GL-R440 (Hitachi High-Tech Fielding Corporation)) heated to 30°C. Measurements were performed using THF as the developing solvent at a flow rate of 1.6 mL / min. An L-3350 RI detector (Hitachi, Ltd.) was used as the detector, and the weight-average molecular weight (Mw) was calculated from the elution time using a molecular weight / elution time curve prepared using standard polystyrene (Tosoh Corporation).

[0088] [Solid content] Xg of the curable resin composition was placed in an aluminum dish weighing Z1g, and after heating at 150°C for 0.5 hours, when the weight of the aluminum dish (including the remaining resin composition) was Z2g, the solid content (mass%) was calculated using the following formula. Solid content (mass%)={(Z2-Z1) / X}×100

[0089] <Preparation of cured maleimide resin film> The curable resin composition (A-1) was applied to a Cu foil (manufactured by Mitsui Mining & Smelting Co., Ltd., product name "3EC-M2S-VLP") using an applicator so that the thickness after drying would be 100 μm, and the coating was dried in a dryer at 130°C for 20 minutes. Subsequently, the coating was irradiated with 3000 mJ / cm using a UV irradiator (a UV irradiator with a conveyor, manufactured by GS Yuasa Corporation, using a metal halide lamp (MAL 500NAL)). 2After irradiation, the film was cured in a nitrogen atmosphere at 200°C for 60 minutes using a nitrogen dryer (manufactured by Yamato Scientific Co., Ltd., model number: DN410I). After curing, the film was cooled to room temperature, and the copper foil was removed by etching with an aqueous ammonium persulfate solution. The film was then dried at 105°C for 30 minutes to produce a cured film (B-1).

[0090] A cured film (B-2) was produced in the same manner as in the production of the cured film (B-1), except that the curable resin composition (A-2) was used instead of the curable resin composition (A-1).

[0091] The following materials were prepared as cured films: B-3: Polyimide film (manufactured by Toray DuPont Co., Ltd., product name "Kapton", product number "200EN") B-4: Liquid crystal polymer (LCP) film (manufactured by Kuraray Co., Ltd., product name "Vecstar", product number "CTQ-100") B-5: PTFE film (manufactured by Nitto Denko Corporation, product name "Nitoflon", product number "#900UL")

[0092] (Examples 1 and 2, Comparative Examples 1 and 2, and Reference Example 1) The dielectric constant (Dk), dielectric loss tangent (Df), and their variations were determined for the prepared cured films using the following procedure, and the frequency dependence was evaluated using the following evaluation criteria. The results are shown in Tables 1 and 2.

[0093] [Measurement of relative permittivity (Dk) and dielectric loss tangent (Df)] A 50 mm x 50 mm test piece was prepared using the cured film. This test piece was dried in a dryer at 105°C for 30 minutes and then left at room temperature (25°C, 52% RH) for 24 hours. The dielectric constant (Dk) and dielectric loss tangent (Df) were then measured from 20 to 100 GHz using a network analyzer (product name "P5003A", manufactured by KEYSIGHT Technologies) and a split cylinder resonator (manufactured by KEYSIGHT Technologies) by the balanced disc resonator method (BCDR method). The measured values of the dielectric constant (Dk) and dielectric loss tangent (Df) were used to calculate the variations in the dielectric constant (Dk) and dielectric loss tangent (Df) according to the following formula. For (B-2), measurements were performed using two sheets stacked on top of each other. Variation in relative permittivity (Dk) = (maximum value of relative permittivity (Dk)) - (minimum value of relative permittivity (Dk)) Variation of dielectric dissipation factor (Df) = (maximum value of dielectric dissipation factor (Df)) - (minimum value of dielectric dissipation factor (Df))

[0094] [Evaluation criteria] Dielectric constant (Dk) rating: A: The maximum value of the relative dielectric constant (Dk) is less than 3.0 and the variation is 0.05 or less. B: The maximum value of the relative dielectric constant (Dk) is 3.0 or more or the variation exceeds 0.05 Dissipation Factor (Df) Rating: A: The maximum dielectric loss tangent (Df) is 3.0 x 10 -3 Less than 0.0005 and variation less than 0.0005 B: The maximum dielectric loss tangent (Df) is 3.0 x 10 -3 or more or variation exceeds 0.0005

[0095] [Table 1]

[0096] [Table 2]

[0097] Compared with Comparative Examples 1 and 2, which used polyimide film and LCP film as the cured film, Examples 1 and 2, which used the cured product of the curable resin composition for antenna substrates of this embodiment, had low relative permittivity (Dk) and dielectric loss tangent (Df), and the frequency dependence of the relative permittivity (Dk) and dielectric loss tangent (Df) was also small. Note that the PTFE film of Reference Example 1 is not suitable for antenna substrates because it has poor adhesion to Cu and organic substrates, etc., and has processability issues. [Explanation of symbols]

[0098] 100, 101...antenna module, 10, 11...antenna substrate, 1a, 1b, 1c, 1d...insulating substrate layer, 2a, 2b, 2c...adhesive layer, 3a, 3b, 3c, 3d...antenna (antenna element), 3e...antenna, 4...conductor pattern, 5...bump, 6...integrated circuit, 30...heat dissipation substrate.

Claims

1. A curable resin composition for an antenna substrate, comprising a maleimide resin.

2. a cured product of the curable resin composition has a relative dielectric constant (Dk) of less than 3.0 at a frequency of 20 GHz to 100 GHz; 2. The curable resin composition according to claim 1, wherein the variation in dielectric constant (Dk) of a cured product of the curable resin composition is 0.05 or less as measured by the following method: Measurement method for variation in relative dielectric constant (Dk): The dielectric constant (Dk) of the cured product of the curable resin composition is measured at frequencies between 20 GHz and 100 GHz at intervals of 10 GHz. The maximum and minimum values of the nine measured values obtained are used to determine the variation in the dielectric constant (Dk). Variation in relative dielectric constant (Dk) = (maximum value of relative dielectric constant (Dk)) - (minimum value of relative dielectric constant (Dk))

3. The cured product of the curable resin composition has a dielectric loss tangent (Df) of 3.0×10 between frequencies of 20 GHz and 100 GHz. －３ is less than 2. The curable resin composition according to claim 1, wherein the variation in dielectric loss tangent (Df) of a cured product of the curable resin composition measured by the following method is 0.0005 or less. Measurement method for variation in dielectric dissipation factor (Df): The dielectric loss tangent (Df) of the cured product of the curable resin composition is measured at frequencies between 20 GHz and 100 GHz in increments of 10 GHz. The maximum and minimum values of the nine measured values obtained are used to perform the following calculation to determine the variation in the dielectric loss tangent (Df). Variation in dielectric dissipation factor (Df) = (maximum value of dielectric dissipation factor (Df)) - (minimum value of dielectric dissipation factor (Df))

4. A cured product of the curable resin composition according to any one of claims 1 to 3.

5. A laminate comprising a resin layer containing a cured product of the curable resin composition according to any one of claims 1 to 3.

6. An antenna module comprising: an antenna substrate containing a cured product of the curable resin composition according to any one of claims 1 to 3; and an antenna electrically connected to the antenna substrate.

7. the antenna substrate includes one or more insulating substrate layers; The antenna module according to claim 6 , wherein at least one of the insulating base material layers includes the cured material.

8. the antenna substrate includes two or more insulating substrate layers and one or more adhesive layers disposed between the insulating substrate layers; The antenna module according to claim 6 , wherein at least one of the insulating substrate layer and the adhesive layer contains the cured product.

9. The antenna module according to claim 6 , further comprising a heat dissipation substrate.

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