Composition, sheet and metal clad laminate

Abstract

To provide a composition that inhibits water absorption and moisture absorption, particularly a composition for obtaining a sheet in which an increase in dielectric loss tangent due to moisture absorption is suppressed, and also to provide a sheet and a metal-clad laminate, each obtained using the composition.SOLUTION: The present invention provides a composition that comprises a fluororesin, inorganic particles, and an organosiloxane, as well as a sheet and a metal-clad laminate, each obtained using the composition.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to compositions, sheets and metal clad laminates. [Background technology]

[0002] High-frequency printed wiring boards with low transmission loss are required. The use of fluororesin films in such high-frequency printed wiring boards is known (Patent Document 1, etc.). In addition, Patent Documents 2 and 3 describe the use of fluororesin containing fillers as wiring board materials.

[0003] Furthermore, Patent Document 4 discloses that a fluororesin composition in which spherical silica particles are blended with a fluororesin is used for a circuit board. Furthermore, Patent Document 5 describes a method of forming a polymer layer on a substrate using a dispersion containing a tetrafluoroethylene-based polymer and a liquid compound having a specific kinematic viscosity and boiling point, thereby obtaining a laminate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-8260 [Patent Document 2] Japanese Patent Application Publication No. 63-259907 [Patent Document 3] Special Publication No. 2022-510017 [Patent Document 4] International Publication No. 2020 / 145133 [Patent Document 5] Japanese Patent Publication No. 2022-69962 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure aims to provide a composition that suppresses water absorption and moisture absorption. It also aims to provide a composition that can provide a sheet that suppresses not only poor appearance due to water absorption but also an increase in dielectric loss tangent due to moisture absorption, and a sheet and a metal clad laminate that use the composition. [Means for solving the problem]

[0006] The present disclosure relates to a composition comprising a fluororesin, inorganic particles, and an organosiloxane. The organosiloxane is contained in an amount of 0.05% by mass or more and 2% by mass or less of the entire composition, and components other than the fluororesin particles, inorganic particles, and organosiloxane are contained in an amount of 10% by mass or less of the composition. is. The inorganic particles are preferably inorganic particles containing silica as an essential component. The fluororesin is preferably a perfluororesin. The perfluoro-based fluororesin is preferably polytetrafluoroethylene (PTFE).

[0007] The silica is preferably spherical silica. The dielectric loss tangent of the silica at 10 GHz is preferably 0.0025 or less.

[0008] The inorganic particles are preferably coated with a silane coupling agent. The content of the inorganic particles is preferably 40% by mass or more of the total composition. The inorganic particles preferably have an average particle size of 0.5 μm or more.

[0009] The viscosity of the organosiloxane is preferably 3 to 18,000 mm / s (25°C). 。

[0010] The organosiloxane is preferably a modified organosiloxane. The modified organosiloxane preferably has at least one group selected from the group consisting of a hydrogen atom, an amino group, an ether group, an epoxy group, a mercapto group, a carboxyl group, an acrylic group, a methacrylic group, a carboxylic anhydride group, an alkyl group, an aralkyl group, a fluoroalkyl group, a perfluoroalkyl group, an ester group, an amide group, and a phenyl group at any or all of its side chains, one end, and both ends.

[0011] The modified polyorganosiloxane preferably has at least one selected from the group consisting of a hydrogen atom, an amino group, a carboxyl group, an acrylic group, a carboxylic anhydride group, an alkyl group, a fluoroalkyl group, a perfluoroalkyl group, an ester group, an amide group, and a phenyl group at any or all of its side chains, one end, and both ends. The modified polyorganosiloxane preferably has at least one selected from the group consisting of a hydrogen atom, an amino group, a carboxyl group, an acrylic group, a fluoroalkyl group, a phenyl group, and a carboxylic anhydride group at either its side chain, one end, or both ends. the fluororesin is polytetrafluoroethylene, the inorganic particles are silica, The content of the inorganic particles is 50% by mass or more and 70% by mass or less, The organosiloxane is preferably at least one selected from the group consisting of dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane, carboxyl-modified polysiloxane, amino-modified polysiloxane, acrylic-modified polysiloxane, carboxylic anhydride-modified polysiloxane, and fluoroalkyl group-modified polysiloxane.

[0012] The present disclosure also relates to a sheet made of the moisture absorption suppressing composition described above. The sheet of the present disclosure preferably exhibits an increase in moisture content of 60 ppm or less when stored for 24 hours in an environment of 30°C and 90% RH. The sheet of the present disclosure preferably has a dielectric loss tangent that increases by 30% or less when stored for 24 hours in an environment of 30°C and 90% RH. The sheet of the present disclosure preferably has a coefficient of linear expansion (CTE) of 200 ppm / K or less.

[0013] The present disclosure also relates to a method for producing the above-mentioned sheet, which is characterized by molding a composition in which fluororesin particles, inorganic particles, and organosiloxane are mixed. In the method for producing the sheet, it is preferable to form the sheet using a composition substantially consisting of fluororesin particles, inorganic particles, and organosiloxane.

[0014] The present disclosure also relates to a metal clad laminate having a metal layer and the above-described sheet as essential layers. The sheet included in the metal clad laminate may contain at least one selected from the group consisting of formaldehyde, formic acid, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane. The metal layer is preferably a copper foil. The present disclosure also provides a circuit board comprising the above-described metal clad laminate in which the metal layer is copper foil. [Effects of the Invention]

[0015] The present disclosure makes it possible to provide a composition that suppresses water and moisture absorption. In particular, sheets obtained using the water and moisture absorption suppressing composition containing the fluororesin of the present disclosure exhibit excellent performance in that they can suppress poor appearance and changes in properties due to water absorption, and also suppress an increase in dielectric loss tangent due to moisture absorption. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present disclosure will be described in detail below. Many studies have been conducted on compositions in which fillers such as inorganic particles are blended with fluororesins or other resins. However, for example, sheets used for circuit boards and the like, which are produced from compositions containing inorganic particles, may have problems such as poor appearance and changes in properties, particularly an increase in the dielectric loss tangent of the sheet, due to the water absorption and hygroscopicity caused by the incorporation of inorganic particles.

[0017] In other applications, sheets, lenses, and sealing materials produced from compositions containing inorganic particles may also have problems such as changes in light diffusion properties due to dimensional changes in light diffusion sheets, changes in refractive index in lenses, and peeling due to dimensional changes in sealing materials, due to moisture absorption caused by the incorporation of inorganic particles.

[0018] The present disclosure makes it possible to provide a composition for obtaining a sheet in which an increase in dielectric loss tangent is suppressed under high humidity conditions, a light diffusion sheet in which light diffusion properties do not change, a lens in which a change in refractive index is small, and an encapsulant with excellent dimensional stability.

[0019] The composition of the present disclosure is characterized by comprising a resin, inorganic particles, and an organosiloxane as essential components. The addition of the organosiloxane inhibits water and moisture absorption, providing a composition that can reduce changes due to water and moisture absorption.

[0020] The shape of the molded article made of the composition of the present disclosure may be a sheet, a lens, an encapsulant, or the like. The composition of the present disclosure may also be a laminate containing the composition as a part of a layer. The composition may also be molded into these shapes from a liquid state by a curing reaction.

[0021] Water absorption indicates the degree of adsorption of water molecules that have clustered together through hydrogen bonds, while hygroscopicity is determined by the degree of adsorption of water molecules (water vapor). While there has traditionally been a demand for suppressing water absorption, there has been no specific mention of hygroscopicity. Water absorption is the effect on liquid water, and even if water absorption can be suppressed, it cannot be said that the effect of water vapor has been suppressed. The sheet of the present disclosure has low water absorption as well as low moisture absorption.

[0022] The composition of the present disclosure is characterized by containing a fluororesin, inorganic particles, and an organosiloxane. That is, the composition of the present disclosure is characterized by blending an organosiloxane with a fluororesin together with inorganic particles. The mechanism by which the addition of organosiloxane suppresses poor appearance due to water absorption and the mechanism by which the increase in dielectric tangent due to moisture absorption is suppressed has not yet been specifically elucidated, but it is thought that in sheets containing fluororesin and inorganic particles, moisture absorption occurs when water vapor is adsorbed into the voids between the inorganic particles and the fluororesin, which is the matrix resin.It is speculated that by mixing an organosiloxane, which has low surface tension, with the fluororesin and inorganic particles to form a composition, the organosiloxane spreads over the surfaces of the inorganic particles (void surfaces), and that a sheet made from this composition prevents water vapor from penetrating into the sheet and prevents the surface of the sheet from adsorbing water vapor and clustered water molecules. In this way, it is believed that the sheet made of the composition of the present disclosure is less likely to absorb water and moisture, thereby suppressing poor appearance and changes in properties, particularly an increase in dielectric loss tangent.

[0023] (organosiloxane) Organosiloxanes as used in the present disclosure are compounds having a Si-O-Si bond (siloxane bond) in which organic substituents are bonded to silicon. The organosiloxanes used in the present disclosure may be oligomeric or polymeric. A typical example of the organosiloxane is a compound in which a methyl group is bonded to silicon. In the present disclosure, dimethylpolysiloxanes in which all side chains and terminals are methyl groups are preferably used, and linear dimethylpolysiloxanes are particularly preferred. Volatile organosiloxanes, such as hexamethyldisiloxane and decamethylcyclopentasiloxane, are not suitable for use in the present disclosure. These volatilize when the sheet is heated to 300°C or higher, making it difficult to achieve the desired effects of the present disclosure.

[0024] In addition, in the present disclosure, it is preferable to use a modified organosiloxane in which some of the methyl groups of the dimethylpolysiloxane are modified with hydrogen atoms or various organic groups. The use of the modified organosiloxane is expected to suppress an increase in the dielectric loss tangent due to moisture absorption in the sheet, as well as to suppress decomposition during firing and the amount of gas generated.

[0025] The organosiloxane used in the present disclosure is preferably a liquid, and its viscosity is 3 to 18,000 mm 2 / s (25°C) is preferable. When the viscosity of the organosiloxane is in the above range, it is preferable in that it is easy to mix and has a high effect of suppressing moisture absorption. The lower limit of organosiloxane viscosity is 5 mm 2 / s (25°C), and more preferably 10 mm 2 / s (25°C), and more preferably 20 mm 2 / s (25°C). The upper limit of the viscosity of the organosiloxane is 10,000 mm 2 / s (25°C), and more preferably 5000mm 2 / s (25°C), and more preferably 2000mm 2 / s (25°C) is most preferred.

[0026] In this disclosure, the viscosity of the organosiloxane is a value measured at 25°C using an Ubbelohde viscometer. When two or more types of organosiloxanes are used in combination, the viscosity at 25°C refers to the viscosity of the mixture.

[0027] The modified organosiloxane may be one in which an organic group other than a hydrogen atom or a methyl group (hereinafter, sometimes referred to as an organic group, etc.) has been introduced into any or all of its side chain, one end, or both ends. For example, one in which an organic group, etc. has been introduced into part of the side chain of the organosiloxane, one in which an organic group, etc. has been introduced into one end of the organosiloxane, one in which an organic group, etc. has been introduced into both ends of the organosiloxane, one in which an organic group, etc. has been introduced into part of the side chain and both ends of the organosiloxane, etc., and an appropriate one may be selected and used. Among these, from the viewpoint of suppressing the rate of increase in the dielectric loss tangent, those in which an organic group or the like is introduced into a part of the side chain are preferred.

[0028] In the present disclosure, "having hydrogen atoms at any one or all of its side chains, one end, and both ends" means that a single hydrogen atom is present at any one or all of its side chains, one end, and both ends, rather than a hydrogen atom present in an organic group.

[0029] The modified organosiloxane may be either a reactive type or a non-reactive type. The organosiloxane used in the present disclosure does not include the silane coupling agent used when coating inorganic particles, which will be described later. Specifically, the organosiloxane is an alkoxy group (-OR (where R has 1 to 6 carbon atoms) ) Those having halogen groups such as hydroxyl groups and chloro groups are not included in the organosiloxanes used in the present disclosure.

[0030] Specific examples of the organic group include a carboxyl group, an amino group, an ether group, an epoxy group, a mercapto group, an acrylic group, a methacrylic group, a carbonyl group, a carboxylic anhydride group, an alkyl group other than a methyl group, an aralkyl group, a fluoroalkyl group, a perfluoroalkyl group, an aryl group, an ester group, and an amide group, or substituents containing these.

[0031] Examples of the alkyl group other than the methyl group include alkyl groups having 1 to 6 carbon atoms, such as ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl, tert-butyl, n-pentyl, and n-hexyl, and preferably n-butyl, n-pentyl, and n-hexyl. The aryl group includes aryl groups having 6 to 10 carbon atoms such as phenyl and naphthyl, and preferably a phenyl group. The fluoroalkyl group and perfluoroalkyl group are linear or branched fluoroalkyl or perfluoroalkyl groups having 1 to 50 carbon atoms, and may contain an ether bond. Preferably, it is a linear or branched fluoroalkyl or perfluoroalkyl group having 1 to 40 carbon atoms, which may contain an ether bond. More preferably, it is a linear or branched fluoroalkyl or perfluoroalkyl group having 1 to 30 carbon atoms, which may contain an ether bond. Particularly preferably, it is a linear fluoroalkyl or perfluoroalkyl group having 1 to 20 carbon atoms, which may contain an ether bond.

[0032] The modified organosiloxane used in the present disclosure preferably has at least one group selected from the group consisting of a hydrogen atom, an amino group, an ether group, an epoxy group, a mercapto group, a carboxyl group, an acrylic group, a methacrylic group, a carboxylic anhydride group, an alkyl group other than a methyl group, an aralkyl group, a fluoroalkyl group, a perfluoroalkyl group, an aryl group, an ester group, an amide group, and a phenyl group at any or all of its side chains, one end, and both ends.

[0033] The modified organosiloxane used in the present disclosure more preferably has at least one group selected from the group consisting of a hydrogen atom, an amino group, a carboxyl group, an acrylic group, a carboxylic anhydride group, an alkyl group, a fluoroalkyl group, a perfluoroalkyl group, an ester group, an amide group, and a phenyl group at any or all of its side chains, one end, and both ends.

[0034] The modified organosiloxane used in the present disclosure more preferably has at least one group selected from the group consisting of a hydrogen atom, an amino group, a carboxyl group, an acrylic group, a fluoroalkyl group, a phenyl group, and a carboxylic anhydride group at either its side chain, one end, or both ends.

[0035] Specific examples of modified organosiloxanes include methylhydrogenpolysiloxane, methylphenylpolysiloxane, which is a copolymer of dimethylsiloxane and diphenylsiloxane, carboxyl-modified polysiloxane, amino-modified polysiloxane, acrylic-modified polysiloxane, methacrylic-modified polysiloxane, fluoroalkyl group-modified polysiloxane, carboxylic anhydride-modified polysiloxane, polyether-modified polysiloxane, epoxy-modified polysiloxane, and epoxy-polyether-modified polysiloxane.

[0036] The polyether in the polyether-modified polysiloxane is preferably a polyalkylene glycol, and examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polytrimethylene glycol, polytetramethylene glycol, polyhexamethylene glycol, and polyalkylene glycols derived from block or random copolymers of ethylene oxide and propylene oxide.

[0037] Examples of organosiloxanes used in the present disclosure include commercially available polydimethylsiloxanes (such as KF-96), methylphenylpolysiloxanes (such as KF-50), methylhydrogenpolysiloxanes (KF-99), carboxyl-modified polysiloxanes (such as X-22-3701E and X-22-162C), amino-modified polysiloxanes (such as KF-868, KF-8012, and KF-8008), acid anhydride-modified polysiloxanes (such as X-22-168), acrylic-modified polysiloxanes (such as X-22-2445), fluoroalkyl-modified polysiloxanes (such as X-22-822), and mercapto-modified polysiloxanes (such as X-22-167B) (all from Shin-Etsu Chemical Co., Ltd.). Other examples include WACKER AF98 / 1000, WACKER L655, and WACKER FINISH WT1270 manufactured by Asahi Kasei Wacker Silicone, and TSF4704 manufactured by Momentive.

[0038] In the present disclosure, as the organosiloxane, dimethylpolysiloxane, methylhydrogenpolysiloxane, methylphenylpolysiloxane, carboxyl-modified polysiloxane, amino-modified polysiloxane, acrylic-modified polysiloxane, carboxylic anhydride-modified polysiloxane, fluoroalkyl group-modified polysiloxane, etc. can be suitably used.

[0039] The organosiloxane is preferably contained in an amount of less than 20% by mass of the total composition. This amount effectively suppresses an increase in the dielectric loss tangent due to moisture absorption in the sheet, thereby lowering the dielectric loss tangent and the linear expansion coefficient of the sheet. The amount is more preferably 10% by mass or less, even more preferably 5% by mass or less, and particularly preferably 2% by mass or less. The lower limit of the organosiloxane amount is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, even more preferably 0.05% by mass or more, and particularly preferably 0.2% by mass or more. This amount effectively suppresses an increase in the dielectric loss tangent due to moisture absorption in the sheet. If the organosiloxane is contained in an amount of 20% by mass or more of the total composition, the dielectric loss tangent and linear expansion coefficient of the sheet tend to be large.

[0040] (Inorganic particles) In the present disclosure, the inorganic particles used are not particularly limited, and examples thereof include one or more types selected from silica, ceramics, talc, mica, aluminum oxide, zinc oxide, tin oxide, titanium oxide, calcium carbonate, calcium oxide, magnesium oxide, potassium titanate, glass fiber, glass chips, glass beads, silicon carbide, calcium fluoride, boron nitride, barium sulfate, molybdenum disulfide, and potassium carbonate whiskers. Two or more types of these may also be used in combination.

[0041] In order to obtain a sheet in which the increase in dielectric loss tangent due to moisture absorption is suppressed, which is one of the objects of the present disclosure, the use of silica as an essential component is advantageous in that it can reduce the relative dielectric constant and dielectric loss tangent, and also reduce the linear expansion coefficient. Therefore, in the present disclosure, it is preferable that the inorganic particles used contain silica as an essential component. When silica is used, the silica surface is Si-O-Si-O, and organosiloxane also has Si-O-Si-O bonds in its main skeleton, so it is more compatible with organosiloxane than other inorganic particles, and combining silica with organosiloxane further enhances the moisture absorption suppression effect.

[0042] The silica content in the inorganic particles is preferably 50% by mass or more, more preferably 65% ​​by mass or more, and even more preferably 80% by mass or more. The inorganic particles having a silica content within the above range are advantageous in that the dielectric loss tangent can be reduced. Alternatively, the inorganic particles may consist solely of silica.

[0043] The shape of the inorganic particles is not particularly limited, but spherical particles are particularly preferred, as spherical particles are easier to process uniformly during drilling and have a small specific surface area and therefore low transmission loss. The silica used is preferably spherical silica particles.

[0044] The spherical inorganic particles mentioned above refer to particles whose particle shape is close to a perfect sphere. Specifically, the sphericity is preferably 0.80 or more, more preferably 0.85 or more, even more preferably 0.90 or more, and most preferably 0.95 or more. The sphericity is calculated by taking a photograph with an SEM and calculating the value from the area and perimeter of the observed particle using the formula (sphericity) = {4π × (area) ÷ (perimeter)²}. The closer to 1, the closer to a perfect sphere. Specifically, the average value measured for 100 particles using an image processing device (Spectris Inc.: FPIA-3000) is used.

[0045] The inorganic particles used in the present disclosure preferably have a D90 / D10 of 2 or more (preferably 2.3 or more, 2.5 or more) and a D50 of 10 μm or less when integrating the volume from the smallest particle size. Furthermore, it is preferable that the D90 / D50 is 1.5 or more (more preferably 1.6 or more). It is preferable that the D50 / D10 is 1.5 or more (more preferably 1.6 or more). Furthermore, it is more preferable that the D50 is 5 μm or less. Since small inorganic particles can enter the gaps between large inorganic particles, excellent filling properties and high fluidity can be achieved. In particular, it is preferable that the particle size distribution has a higher frequency on the small particle size side compared to a Gaussian curve. The particle size can be measured using a laser diffraction / scattering particle size distribution analyzer. Since coarse particles make it difficult to form a thin sheet, it is preferable that coarse particles having a particle size larger than a predetermined value are removed using a filter or the like.

[0046] The inorganic particles preferably have a water absorption of 1.0% or less, more preferably 0.5% or less. If the water absorption of the inorganic particles is within the above range, the sheet can be prevented from absorbing moisture, and thus a sheet can be obtained in which an increase in the dielectric tangent due to moisture absorption is prevented. The water absorption of inorganic particles is based on the mass of the inorganic particles when dry. To measure water absorption, a dry sample is left at 40°C and 80% RH for 1 hour, and the water generated by heating to 200°C is measured using a Karl Fischer moisture analyzer, and then calculated.

[0047] The inorganic particles preferably have an average particle size of 0.5 μm or more, where the average particle size is the D50 value measured by a laser analysis particle size distribution analyzer. If the average particle size is less than 0.5 μm, the inorganic particles may aggregate, making it impossible to obtain a sufficient effect. The upper limit of the average particle size is not particularly limited, but is preferably 250 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less.

[0048] The dielectric loss tangent of the silica at 10 GHz is preferably 0.0025 or less. This value is preferable because it results in low loss of the sheet. The upper limit is more preferably 0.002, even more preferably 0.0015, and most preferably 0.0010. On the other hand, the lower limit of the dielectric loss tangent is preferably 0.00001.

[0049] In this disclosure, the dielectric loss tangent of silica measured at 10 GHz was measured using a cylindrical cavity resonator and a network analyzer. A filler powder sample was filled into a quartz tube and loaded into the resonator. The resonator characteristics (resonant frequency and Q value) were obtained before and after inserting the sample, and the dielectric loss tangent was calculated from the results. This measurement method complies with the Japanese Industrial Standard JIS 2565 Microwave Ferrite Core Test Method, and measurements were performed in an environment with a room temperature of 25°C and a humidity of 40%.

[0050] Alternatively, the inorganic particles can be measured using the above-mentioned methods after the sheet is heated in an air atmosphere at 600°C for 30 minutes to burn off the fluororesin and the inorganic particles are removed.

[0051] The inorganic particles are preferably surface-treated. By previously subjecting the inorganic particles to surface treatment, aggregation of the inorganic particles can be suppressed, and the inorganic particles can be favorably dispersed in the resin composition. It is also preferable in that the linear expansion coefficient can be reduced.

[0052] The surface treatment is not particularly limited, and any known treatment can be used. Specific examples include treatment with a silane coupling agent such as an epoxy silane, amino silane, isocyanate silane, vinyl silane, acrylic silane, hydrophobic alkyl silane, phenyl silane, or fluorinated alkyl silane, which has a reactive functional group; plasma treatment; and fluorination treatment.

[0053] Among these, it is preferable to use inorganic particles that have been surface-treated with a silane coupling agent and coated with the silane coupling agent. Coating with a silane coupling agent is advantageous in that it can lower the dielectric loss tangent.

[0054] Examples of the silane coupling agent include epoxy silanes such as γ-glycidoxypropyltriethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, amino silanes such as aminopropyltriethoxysilane and N-phenylaminopropyltrimethoxysilane, isocyanate silanes such as 3-isocyanatepropyltrimethoxysilane, vinyl silanes such as vinyltrimethoxysilane, and acrylic silanes such as acryloxytrimethoxysilane.

[0055] The inorganic particles of the present disclosure are preferably surface-treated with a silane coupling agent in an amount of 0.05 to 30% by mass based on the inorganic particles. The surface treatment is not particularly limited and can be carried out by any known method. Specifically, for example, the surface treatment can be carried out by treating the inorganic particles with a silane coupling agent in a solution state in which the silane coupling agent is dissolved in a solvent, or in a solvent-free state.

[0056] The spherical silica particles may be commercially available silica particles that satisfy the above-mentioned properties. Examples of commercially available silica particles include Denka Fused Silica FB Grade (manufactured by Denka Company Ltd.), Denka Fused Silica SFP Grade (manufactured by Denka Company Ltd.), Excelica (manufactured by Tokuyama Corporation), high-purity synthetic spherical silica particles Adma Fine (manufactured by Admatechs Co., Ltd.), Admanano (manufactured by Admatechs Co., Ltd.), and Adma Fuse (manufactured by Admatechs Co., Ltd.).

[0057] The inorganic particles are preferably contained in a proportion of 40% by mass or more of the total composition. This amount is preferable in that it achieves low thermal expansion while maintaining a low dielectric constant and low loss. It also allows for a composition with excellent moldability. The amount is more preferably 50% by mass or more, and even more preferably 55% by mass or more. There is no particular upper limit to the amount of inorganic particles, but it is preferably 80% by mass or less, and even more preferably 70% by mass or less.

[0058] (Fluorine resin) Since fluororesins have low dielectric properties, they can be suitably used to obtain a sheet in which an increase in dielectric loss tangent due to moisture absorption is suppressed, which is one of the objects of the present disclosure. For this purpose, the composition of the present disclosure preferably contains a fluororesin.

[0059] The fluororesin that can be used in the present disclosure is not particularly limited, and examples thereof include polytetrafluoroethylene (PTFE), tetrafluoroethylene [TFE] / hexafluoropropylene [HFP] copolymer [FEP], TFE / alkyl vinyl ether copolymer [PFA], TFE / HFP / alkyl vinyl ether copolymer [EPA], TFE / chlorotrifluoroethylene [CTFE] copolymer, TFE / ethylene copolymer [ETFE], polyvinylidene fluoride [PVdF], tetrafluoroethylene having a molecular weight of 300,000 or less [LMW-PTFE], etc. These may be used alone or in combination of two or more.

[0060] In particular, perfluoro-based fluororesin is preferred. Among these, polytetrafluoroethylene resin (PTFE) is particularly preferred from the viewpoint of low dielectric constant. PTFE having fibrillar properties is preferred. Fibrillar PTFE means PTFE that can be paste-extruded as unsintered polymer powder.

[0061] The PTFE may be modified polytetrafluoroethylene (hereinafter referred to as modified PTFE), homopolytetrafluoroethylene (hereinafter referred to as homoPTFE), or a mixture of modified PTFE and homoPTFE. From the viewpoint of maintaining good moldability of polytetrafluoroethylene, the content of modified PTFE in the polymeric PTFE is preferably 10% by weight or more and 98% by weight or less, and more preferably 50% by weight or more and 95% by weight or less. The homo-PTFE is not particularly limited, and homo-PTFE disclosed in JP-A-53-60979, JP-A-57-135, JP-A-61-16907, JP-A-62-104816, JP-A-62-190206, JP-A-63-137906, JP-A-2000-143727, JP-A-2002-201217, WO 2007 / 046345 pamphlet, WO 2007 / 119829 pamphlet, WO 2009 / 001894 pamphlet, WO 2010 / 113950 pamphlet, WO 2013 / 027850 pamphlet, etc. can be suitably used. Among these, homo-PTFE having high stretchability and disclosed in JP-A Nos. 57-135, 63-137906, 2000-143727, 2002-201217, WO 2007 / 046345, WO 2007 / 119829, WO 2010 / 113950, etc. is preferred.

[0062] The modified PTFE is composed of TFE and a monomer other than TFE (hereinafter referred to as a modified monomer). Modified PTFE includes, but is not limited to, PTFE uniformly modified with the modified monomer, PTFE modified at the beginning of the polymerization reaction, and PTFE modified at the end of the polymerization reaction. The modified PTFE is preferably a TFE copolymer obtained by polymerizing a small amount of a monomer other than TFE together with TFE within a range that does not significantly impair the properties of the TFE homopolymer. Modified PTFEs that can be suitably used include those disclosed in, for example, JP-A-60-42446, JP-A-61-16907, JP-A-62-104816, JP-A-62-190206, JP-A-64-1711, JP-A-2-261810, JP-A-11-240917, JP-A-11-240918, WO 2003 / 033555 pamphlet, WO 2005 / 061567 pamphlet, WO 2007 / 005361 pamphlet, WO 2011 / 055824 pamphlet, WO 2013 / 027850 pamphlet, and the like. Among these, modified PTFEs having high stretchability and disclosed in JP-A Nos. 61-16907, 62-104816, 64-1711, 1999-240917, WO 2003 / 033555, WO 2005 / 061567, WO 2007 / 005361, WO 2011 / 055824, etc. are preferred.

[0063] The modified PTFE contains TFE units derived from TFE and modified monomer units derived from a modified monomer. The modified monomer units are a part of the molecular structure of the modified PTFE and are derived from the modified monomer. The modified PTFE preferably contains the modified monomer units in an amount of 0.001 to 0.500% by weight, more preferably 0.01 to 0.30% by weight, of the total monomer units. The total monomer units are the parts derived from all monomers in the molecular structure of the modified PTFE.

[0064] The modifying monomer is not particularly limited as long as it is copolymerizable with TFE, and examples thereof include perfluoroolefins such as hexafluoropropylene (HFP), chlorofluoroolefins such as chlorotrifluoroethylene (CTFE), hydrogen-containing fluoroolefins such as trifluoroethylene and vinylidene fluoride (VDF), perfluorovinyl ethers, perfluoroalkylethylenes (PFAE), ethylene, etc. The modifying monomer used may be one type or multiple types.

[0065] The perfluorovinyl ether is not particularly limited, and examples thereof include perfluorounsaturated compounds represented by the following general formula (1). CF2 = CF-ORf (1) (In the formula, Rf represents a perfluoroorganic group.)

[0066] In this specification, a perfluoroorganic group is an organic group in which all hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms. The perfluoroorganic group may have an ether oxygen.

[0067] An example of perfluorovinyl ether is perfluoro(alkyl vinyl ether) (PAVE) in which Rf in the above general formula (1) is a perfluoroalkyl group having 1 to 10 carbon atoms. The number of carbon atoms in the perfluoroalkyl group is preferably 1 to 5. Examples of the perfluoroalkyl group in PAVE include perfluoromethyl group, perfluoroethyl group, perfluoropropyl group, perfluorobutyl group, perfluoropentyl group, and perfluorohexyl group. Preferred PAVEs are perfluoropropyl vinyl ether (PPVE) and perfluoromethyl vinyl ether (PMVE).

[0068] The perfluoroalkylethylene (PFAE) is not particularly limited, and examples thereof include perfluorobutylethylene (PFBE) and perfluorohexylethylene (PFHE).

[0069] The modifying monomer in the modified PTFE is preferably at least one selected from the group consisting of HFP, CTFE, VDF, PAVE, PFAE, and ethylene.

[0070] The fluororesin is preferably non-melt-processable. "Non-melt-processable" means that the resin does not have sufficient fluidity even when heated above its melting point, and cannot be molded by melt molding techniques commonly used for resins. PTFE falls into this category.

[0071] In the present disclosure, it is preferable to use such a non-melt-processable fluororesin and form it into a sheet by a molding method that fibrillates it. The molding method will be described later.

[0072] The PTFE preferably has an SSG of 2.0 to 2.3. The use of such PTFE facilitates the production of a PTFE membrane with high strength (cohesion and puncture strength per unit thickness). PTFE with a large molecular weight has long molecular chains, making it difficult to form a structure in which the molecular chains are regularly arranged. In this case, the length of the amorphous portion increases, and the degree of entanglement between molecules increases. It is believed that when the degree of entanglement between molecules is high, the PTFE membrane is less likely to deform under an applied load and exhibits excellent mechanical strength. Furthermore, the use of PTFE with a large molecular weight facilitates the production of a PTFE membrane with a small average pore size.

[0073] The lower limit of the SSG is more preferably 2.05, and even more preferably 2.1, and the upper limit of the SSG is more preferably 2.25, and even more preferably 2.2.

[0074] Standard specific gravity (SSG) was measured by preparing a sample in accordance with ASTM D-4895-89 and measuring the specific gravity of the obtained sample by the water displacement method.

[0075] In the present disclosure, the molecular weight (number average molecular weight) of the PTFE constituting the PTFE powder is preferably, for example, in the range of 2 million to 12 million. The lower limit of the molecular weight of the PTFE may be 3 million or 4 million. The upper limit of the molecular weight of the PTFE may be 10 million.

[0076] Methods for measuring the number average molecular weight of PTFE include a method of determining it from standard specific gravity and a method of measuring dynamic viscoelasticity in a melt. The method of determining it from standard specific gravity can be carried out by the water displacement method in accordance with ASTM D-792 using a sample molded in accordance with ASTM D-4895 98. The measurement method using dynamic viscoelasticity is explained, for example, by S. Wu in Polymer Engineering & Science, 1988, Vol. 28, 538 and the same document, 1989, Vol. 29, 273.

[0077] The refractive index of the PTFE is preferably in the range of 1.2 to 1.6. Having such a refractive index is preferable in terms of low dielectric constant. The refractive index can be adjusted to fall within the above range by, for example, adjusting the polarizability or the flexibility of the main chain. The lower limit of the refractive index is more preferably 1.25, more preferably 1.30, and most preferably 1.32. The upper limit of the refractive index is more preferably 1.55, more preferably 1.50, and most preferably 1.45.

[0078] The refractive index is a value measured using a refractometer (Abbemat 300).

[0079] The PTFE preferably has a maximum endothermic peak temperature (crystalline melting point) of 340±7°C.

[0080] The PTFE may be a low-melting-point PTFE having a maximum peak temperature of 338°C or lower on the endothermic curve on the crystalline melting curve measured by a differential scanning calorimeter, or a high-melting-point PTFE having a maximum peak temperature of 342°C or higher on the endothermic curve on the crystalline melting curve measured by a differential scanning calorimeter.

[0081] The low-melting-point PTFE powder is a powder produced by emulsion polymerization, and has the maximum endothermic peak temperature (crystalline melting point) described above, a dielectric constant (ε) of 2.08 to 2.2, and a dielectric dissipation factor (tan δ) of 1.9 × 10 -4 ~4.0×10 -4 Examples of commercially available products include Polyflon fine powders F201, F203, F205, F301, and F302 manufactured by Daikin Industries, Ltd., CD090 and CD076 manufactured by Asahi Glass Co., Ltd., and TF6C, TF62, and TF40 manufactured by DuPont.

[0082] The high melting point PTFE powder is also a powder produced by emulsion polymerization, and has the above-mentioned maximum endothermic peak temperature (crystalline melting point), a dielectric constant (ε) of 2.0 to 2.1, and a dielectric dissipation factor (tan δ) of 1.6 × 10 -4 ~2.2×10 -4 Commercially available products include Polyflon fine powder F104 and F106 manufactured by Daikin Industries, Ltd., CD1, CD141, and CD123 manufactured by Asahi Glass Co., Ltd., and TF6 and TF65 manufactured by DuPont.

[0083] The powder formed by secondary aggregation of both PTFE polymer particles usually preferably has an average particle size of 250 to 2000 μm. In particular, granulated powder obtained by granulation using a solvent is preferred from the viewpoint of improving fluidity when filling a mold during preforming.

[0084] Powdered PTFE that satisfies the above-mentioned parameters can be obtained by a conventional manufacturing method, for example, following the manufacturing methods described in International Publication Nos. 2015-080291 and 2012-086710.

[0085] (Resins other than fluororesins) The composition of the present disclosure may use a resin other than a fluororesin as the resin. Examples of resins other than fluororesins include cellulose triacetate film, cycloolefin polymer, cycloolefin copolymer, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, transparent polyimide, thermoplastic polyimide, polyacrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, syndiotactic polystyrene, polymethylpentene, epoxy resin, alicyclic epoxy resin, silicone resin (excluding those included in the above organosiloxane), polyphenylene ether, modified polyphenylene ether, polyurethane, phenolic resin, bismaleimide resin, cyanate resin, urea resin, melamine resin, and unsaturated polyester resin.

[0086] (composition) The composition of the present disclosure contains the organosiloxane, inorganic particles, and a fluororesin or a resin other than a fluororesin. The composition of the present disclosure may contain other components as needed, but is preferably substantially composed of an organosiloxane, inorganic particles, and a fluororesin or a resin other than a fluororesin, and is particularly preferably composed of an organosiloxane, inorganic particles, and a fluororesin. In the present disclosure, the term "substantially" means that the content of components other than fluororesin particles, resins other than fluororesin, inorganic particles, and organosiloxane is 10 mass% or less in the composition. Furthermore, the composition of the present disclosure preferably consists only of organosiloxane, inorganic particles, and fluororesin or resins other than fluororesin. In particular, it is preferable that the composition consist only of organosiloxane, inorganic particles, and fluororesin.

[0087] (Method of producing the composition) The composition of the present disclosure can be obtained, for example, by mixing the above-described resin particles, inorganic particles, and organosiloxane components by stirring or the like. The mixing conditions are not particularly specified, but mixing can be performed by stirring at room temperature using a mixer such as a Wonder Crusher. If the stirring time is too short, mixing may be insufficient, and if it is too long, molecular scission and fiberization of the resin may occur, so it is preferable to stir for an appropriate time. Furthermore, stirring at a low temperature in the presence of dry ice can prevent molecular scission and fiberization of the resin and enable mixing. For example, a composition can be obtained under the following conditions, and a sheet can be obtained from the obtained composition by the sheet manufacturing method described below.

[0088] When producing a sheet by powder rolling molding, it is preferable to weigh out the resin particles, inorganic particles, and organosiloxane components in the desired proportions and stir them in a Wonder Crusher at room temperature for 10 seconds to 10 minutes. Stirring may be performed once or in two or more stages.

[0089] When producing a sheet by paste extrusion molding, it is preferable to weigh out the desired amounts of the resin particles, inorganic particles, and organosiloxane components and mix them in a mixer in the presence of dry ice. The temperature during mixing is preferably −10° C. or lower. It is also preferable to add 18 to 23 mass % of an extrusion aid such as oil (IP Solvent 2028) to the obtained mixed powder, mix it, and then age it for about 5 hours.

[0090] (sheet) The compositions of the present disclosure are suitable for use in forming sheets. The present disclosure also relates to a sheet made of the above composition.

[0091] The sheet of the present disclosure can suppress water absorption and moisture absorption. The water absorption rate is preferably 0.1 wt% or less, more preferably 0.08 wt% or less, and most preferably 0.04 wt% or less. The water absorption rate is a value calculated in accordance with IPC TM650 2.6.2.1.

[0092] The sheet of the present disclosure preferably exhibits a moisture content increase of 60 ppm or less when stored for one week under an environment of 30°C and 90% RH. If the moisture content increase is 60 ppm or less, it can be said that moisture absorption is suppressed. The moisture content increase is more preferably 30 ppm or less, and even more preferably 15 ppm or less.

[0093] The increase in moisture content was calculated by measuring the moisture content generated by heating at 250°C using a Karl Fischer moisture content analyzer.

[0094] The sheet of the present disclosure can also reduce the surface liquid repellent tension. The surface liquid repellent tension can be evaluated by the following method. The sheet was immersed in a "wet tension test mixture" manufactured by Wako Pure Chemical Industries, Ltd. at room temperature for 1 minute, then washed with distilled water, and visually inspected to see if the wet tension test mixture had penetrated into the sheet. Wet tension test mixtures No. 22.6 to 70.0 were used, and the value of the test liquid with the lowest surface tension among the wet tension test mixtures that showed no penetration was taken as the critical liquid repellency result. There are different types of mixed liquids for wetting tension tests, each with a different wetting tension (at 23°C), and each contains a colorant, so it is possible to visually check whether or not they penetrate into the test specimen. The critical liquid repellent tension is preferably 37 mN / M or less, more preferably 32 mN / M, and most preferably 22.6 mN / M.

[0095] The sheet of the present disclosure is one that suppresses fluctuations in dielectric loss tangent due to moisture absorption, particularly when a composition containing a fluororesin is used. The sheet of the present disclosure preferably has a relative dielectric constant of 3.5 or less at 10 GHz, which is preferable in that the dielectric loss is low when the relative dielectric constant is within this range. The upper limit of the relative dielectric constant is more preferably 3.2, and even more preferably 3.1, while the lower limit of the relative dielectric constant is preferably 2.0, and more preferably 2.5.

[0096] The sheet of the present disclosure preferably has a dielectric loss tangent of 0.0015 or less at 10 GHz. Setting the dielectric loss tangent within this range is preferable because it can reduce the loss of electrical signals in the circuit. The dielectric loss tangent is more preferably 0.0012 or less, and even more preferably 0.0011 or less. Meanwhile, the lower limit of the dielectric loss tangent is preferably 0.00001.

[0097] The relative permittivity (Dk) and dielectric loss tangent (Df) of the sheet at 10 GHz in this disclosure are values ​​obtained by measuring Dk and Df at 25°C and 10 GHz using a split cylinder type permittivity / dielectric loss tangent measuring device (manufactured by EM Lab).

[0098] The sheet of the present disclosure preferably exhibits an increase in dielectric tangent of 30% or less when stored for 24 hours in an environment of 30°C and 90% RH, more preferably 20% or less, and even more preferably 12% or less.

[0099] The rate of increase in the dielectric loss tangent was calculated by placing each sample in a thermostatic oven maintained at 30°C and 90% RH, tracking the change in the dielectric loss tangent after 24 hours, and using the following formula: Increase rate (%) = (dielectric loss tangent after 24 hours - dielectric loss tangent before humidity test) / dielectric loss tangent before humidity test × 100

[0100] The sheet of the present disclosure preferably has a coefficient of linear expansion (CTE) of 200 ppm / K or less. A concentration within the above range is preferable in that it results in a sheet with low shrinkage and excellent dimensional stability. The upper limit is more preferably 150 ppm / K, even more preferably 100 ppm / K, and most preferably 70 ppm / K. The lower limit is not particularly limited, but is preferably 10 ppm / K, and more preferably 20 ppm / K.

[0101] The linear expansion coefficient in this disclosure is a value obtained by performing TMA measurement using a TMA-7100 (manufactured by Hitachi High-Tech Science Corporation) in a tensile mode, using a sheet cut to a length of 20 mm, width of 5 mm, and thickness of 150 μm as a sample piece, setting the distance between chucks to 10 mm, and determining the linear expansion coefficient from the amount of displacement of the sample at a heating rate of 2°C / min from 0 to 150°C while applying a load of 49 mN.

[0102] In the present disclosure, when a modified organosiloxane is used as the organosiloxane, a sheet can be obtained in which moisture absorption is suppressed and decomposition of the organosiloxane during firing is suppressed.

[0103] The sheet of the present disclosure preferably has a thickness of less than 300 μm. Even if the sheet of the present disclosure is thin, it can sufficiently achieve its purpose. From this perspective, it is more preferably less than 200 μm, and even more preferably less than 150 μm. Furthermore, if the sheet can be processed to a thickness of 100 μm or less as necessary, it can be widely applied to substrates of various thicknesses, which is preferable.

[0104] (Sheet manufacturing method) The sheet of the present disclosure can be obtained by molding a composition containing the resin particles, inorganic particles, and organosiloxane described above. The manufacturing method is not limited, but suitable methods include paste extrusion molding, powder rolling molding, and the like.

[0105] The present disclosure also relates to a method for producing the above-mentioned sheet, which is characterized by molding a composition in which fluororesin particles, inorganic particles, and organosiloxane are mixed. In the method for producing a sheet according to the present disclosure, it is preferable to use a composition substantially consisting of fluororesin particles, inorganic particles, and organosiloxane for molding.

[0106] As described above, it is preferable to use a non-melt-processable fluororesin as the fluororesin used in the sheet of the present disclosure. When such a fluororesin is used and is molded into a sheet, it is preferable to mold it by fibrillating powdered PTFE as a raw material.

[0107] The powdered PTFE preferably has a primary particle diameter of 0.05 to 10 μm. The use of such a powder offers the advantages of excellent moldability and dispersibility. The primary particle diameter here is a value measured in accordance with ASTM D 4895.

[0108] The powdered PTFE preferably contains 50% by mass or more, and more preferably 80% by mass or more, of polytetrafluoroethylene resin having a secondary particle diameter of 500 μm or more. The presence of PTFE having a secondary particle diameter of 500 μm or more within this range is advantageous in that a composite sheet with high strength can be produced. By using PTFE with a secondary particle diameter of 500 μm or more, a mixture sheet with lower resistance and excellent toughness can be obtained.

[0109] The lower limit of the secondary particle diameter is more preferably 300 μm, and even more preferably 350 μm. The upper limit of the secondary particle diameter is more preferably 700 μm or less, and even more preferably 600 μm or less. The secondary particle diameter can be determined, for example, by a sieving method.

[0110] The powdered PTFE preferably has an average primary particle size of 50 nm or more, more preferably 100 nm or more, even more preferably 150 nm or more, and particularly preferably 200 nm or more, since this allows for the production of a sheet with higher strength and excellent homogeneity. The larger the average primary particle diameter of PTFE, the more effectively the paste extrusion pressure can be suppressed when the powder is used for paste extrusion molding, and the better the moldability. The upper limit is not particularly limited, but may be 500 nm. From the viewpoint of productivity in the polymerization step, it is preferably 350 nm.

[0111] The average primary particle diameter can be determined by preparing a calibration curve of the transmittance of 550 nm projected light per unit length of an aqueous dispersion of PTFE obtained by polymerization, the polymer concentration of which is adjusted to 0.22% by mass, and the average primary particle diameter determined by measuring the unidirectional diameter in a transmission electron microscope photograph, and measuring the transmittance of the aqueous dispersion to be measured, and then using the calibration curve.

[0112] The PTFE used in the present disclosure may have a core-shell structure. Examples of PTFE having a core-shell structure include modified polytetrafluoroethylene, which contains a core of high molecular weight polytetrafluoroethylene and a shell of lower molecular weight polytetrafluoroethylene or modified polytetrafluoroethylene in the particles. Examples of such modified polytetrafluoroethylene include the polytetrafluoroethylene described in JP-A-2005-527652.

[0113] There are no particular limitations on the specific methods of paste extrusion molding and powder rolling molding, but the following describes general methods.

[0114] (Paste extrusion molding) The method for producing the sheet may include the steps of: (1a) mixing the composition containing the fluororesin powder, inorganic particles, and organosiloxane obtained using a hydrocarbon surfactant with an extrusion aid; (1b) paste-extrusion molding the resulting mixture; (1c) rolling the extrudate obtained by extrusion molding; (1d) drying the rolled sheet; and (1e) firing the dried sheet to obtain a molded product. The paste extrusion molding can also be carried out by adding conventionally known additives such as pigments to the composition.

[0115] The extrusion aid is not particularly limited, and any commonly known extrusion aid can be used, such as hydrocarbon oil.

[0116] (Powder rolling molding) The sheet can also be formed by powder rolling molding. Powder rolling molding is a method in which a resin powder is fibrillated by applying shear force, and then formed into a sheet. This method may include a subsequent step of firing the powder to obtain a molded product. More specifically, the composition containing the fluororesin powder, inorganic particles, and organosiloxane is mixed while being subjected to shear force (step (1)). Step (2) of forming the mixture obtained in step (1) into a bulk form; and Step (3) of rolling the bulk mixture obtained in step (2) into a sheet. The above-mentioned manufacturing method can be used to obtain the above-mentioned polymer.

[0117] When forming a sheet by such powder rolling molding, it is preferable to mix and mold only the fluororesin powder, inorganic particles, and organosiloxane. The method may further include a step (4) of firing the sheet-like material obtained above at 200 to 400° C. for 1 to 60 minutes. Step (2) may be omitted.

[0118] The sheet of the present disclosure may also be formed by a casting method in which a solution or dispersion containing a fluororesin, inorganic particles, and organosiloxane is prepared, and then the solution or dispersion is applied to a substrate and dried.

[0119] Furthermore, when a baking step is performed at a temperature of 300°C or higher during the production of the above-mentioned sheet, if the baking time is, for example, within about 30 minutes, the decomposition of the organosiloxane can be limited to a certain extent, and a sheet having the effects of the present disclosure can be obtained.

[0120] (Laminate) The sheet of the present disclosure can be used, for example, by laminating it with a metal layer as a sheet for a circuit board, for example, a metal clad laminate in which a metal layer is bonded to one or both sides of the above-mentioned sheet.

[0121] The present disclosure also relates to a metal clad laminate having a metal layer and the above-described sheet as essential layers. As described above, the sheet containing the fluororesin of the present disclosure can be particularly suitably used in circuit board applications, and can therefore be suitably used as such a metal clad laminate.

[0122] Examples of the metal layer include copper foil, gold foil, silver foil, platinum foil, ruthenium foil, etc. Among these, copper foil is preferred because of its low conductor loss.

[0123] The copper foil preferably has an Rz of 1.6 μm or less. The sheet of the present disclosure also has excellent adhesion to copper foil with a high smoothness of Rz of 1.6 μm or less. Furthermore, the copper foil only needs to have an Rz of 1.6 μm or less on at least the surface that adheres to the sheet, and the Rz value of the other surface is not particularly limited. The Rz is the sum of the highest point (maximum peak height: Rp) and the deepest point (maximum valley depth: Rv). The surface roughness is the ten-point average roughness specified in JIS-B0601. In this specification, the Rz is a value measured using a surface roughness meter (product name: Surfcom 470A, manufactured by Tokyo Seiki Co., Ltd.) with a measurement length of 4 mm.

[0124] The thickness of the copper foil is not particularly limited, but is preferably in the range of 1 to 100 μm, more preferably in the range of 5 to 50 μm, and even more preferably in the range of 9 to 35 μm.

[0125] The copper foil is not particularly limited, and specific examples include rolled copper foil and electrolytic copper foil.

[0126] The copper foil having an Rz of 1.6 μm or less is not particularly limited, and commercially available products can be used. Examples of commercially available copper foils having an Rz of 1.6 μm or less include electrolytic copper foil CF-T9DA-SV-18 (thickness 18 μm / Rz 0.85 μm) (manufactured by Fukuda Metal Foil & Powder Co., Ltd.).

[0127] The copper foil may be surface-treated to enhance the adhesive strength to the sheet of the present disclosure.

[0128] The surface treatment is not particularly limited, but may be a silane coupling treatment, plasma treatment, corona treatment, UV treatment, electron beam treatment, or the like. The reactive functional group of the silane coupling agent is not particularly limited, but from the viewpoint of adhesion to the resin substrate, it is preferable that the reactive functional group has at least one selected from an amino group, a (meth)acrylic group, a mercapto group, and an epoxy group at the terminal. Furthermore, the hydrolyzable group is not particularly limited, but may include alkoxy groups such as a methoxy group and an ethoxy group. The copper foil used in the present disclosure may have a rust-preventive layer (such as an oxide film such as chromate), a heat-resistant layer, or the like formed thereon.

[0129] The surface-treated copper foil having a surface treatment layer of the above-mentioned silane compound on the copper foil surface can be produced by preparing a solution containing the silane compound and then surface treating the copper foil with this solution.

[0130] The copper foil may have a roughened layer on the surface from the viewpoint of improving adhesion to the sheet. If the roughening treatment is likely to degrade the performance required in the present disclosure, the amount of roughening particles electrodeposited on the copper foil surface may be reduced as needed, or the roughening treatment may not be performed at all.

[0131] In order to improve various properties, one or more layers selected from the group consisting of a heat-resistant layer, a rust-proofing layer, and a chromate layer may be provided between the copper foil and the surface treatment layer. These layers may be a single layer or multiple layers.

[0132] The metal clad laminate of the present disclosure may further include layers other than the metal layer and the sheet of the present disclosure. The layers other than the metal layer and the sheet are preferably layers made of at least one selected from the group consisting of polyimide, modified polyimide, liquid crystal polymer, polyphenylene sulfide, cycloolefin polymer, polystyrene, epoxy resin, bismaleimide, polyphenylene oxide, modified polyphenylene ether, polyphenylene ether, and polybutadiene.

[0133] These layers other than the metal layer and the sheet are not particularly limited as long as they are made of the above-mentioned resins, and the thickness of the layers other than the metal layer and the sheet is preferably within the range of 12.5 to 260 μm.

[0134] In the metal clad laminate of the present disclosure, the metal layer may be formed on one or both sides of the sheet. Methods for forming the metal layer include laminating (adhering) the metal layer to the surface of a roll sheet, vapor deposition, plating, etc. Methods for laminating the metal layer include a method using heat pressing. The heat pressing temperature may be from the melting point of the sheet −150°C to the melting point of the sheet +40°C. The heat pressing time is, for example, 1 to 30 minutes. The laminate can be produced by a method using a heat pressing pressure of 0.1 to 10 MPa.

[0135] The sheet included in the metal clad laminate of the present disclosure may contain at least one selected from the group consisting of formaldehyde, formic acid, and hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane. When producing the metal clad laminate, the processing temperature reaches 300°C or higher, causing decomposition of the organosiloxane included in the sheet. When the organosiloxane decomposes, formaldehyde, formic acid, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane are generated, which are derived from the organic group of the organosiloxane. Therefore, the sheet included in the metal clad laminate contains at least one selected from the group consisting of formaldehyde, formic acid, and hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane.

[0136] In the present disclosure, the presence of formaldehyde, formic acid, and hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane in the sheet contained in the metal clad laminate can be confirmed by a method in which the sheet is heated to 360°C, the evolved gas is collected, and the gas is analyzed by thermal desorption GCMS.

[0137] When a sheet included in a metal clad laminate contains, for example, 50 ppm or more of formaldehyde, formic acid, and at least one selected from the group consisting of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane, it can be said that the sheet used in producing the metal clad laminate contained an organosiloxane.

[0138] The metal clad laminate of the present disclosure is not particularly limited in its application, and is suitably used as a circuit board. The present disclosure also relates to a circuit board having the above-described metal clad laminate. A circuit board is a plate-like component that electrically connects electronic components such as semiconductors and capacitor chips and simultaneously arranges and fixes them in a limited space. There are no particular limitations on the configuration of the circuit board formed from the metal clad laminate of the present disclosure. The circuit board may be any of a rigid board, a flexible board, and a rigid-flexible board. The circuit board may be any of a single-sided board, a double-sided board, and a multilayer board (such as a built-up board). In particular, it can be suitably used for flexible boards and rigid boards. In particular, it can be suitably used as a printed circuit board for high frequencies of 10 GHz or more.

[0139] In this disclosure, the term "high-frequency circuit" refers not only to a circuit that simply transmits only high-frequency signals, but also to a circuit that also includes a transmission line that converts a high-frequency signal into a low-frequency signal and outputs the generated low-frequency signal to the outside, a transmission line for supplying power to drive high-frequency compatible components, and other transmission lines that transmit signals other than high-frequency signals, all of which are installed on the same plane.The circuit can also be used as a circuit board for an antenna, a filter, etc. The present disclosure also provides an antenna formed from the circuit board, and is particularly suitable as a millimeter-wave antenna for mobility devices such as automobiles and aircraft.

[0140] The circuit board is not particularly limited, and can be produced by a general method using the above-mentioned metal clad laminate.

[0141] The sheet and metal clad laminate of the present disclosure are used as electric and electronic components, for example, antennas used in electronic devices and communication devices such as ETC, GPS, wireless LAN, and mobile phones, high-speed transmission connectors, CPU sockets, millimeter wave and quasi-millimeter wave radars such as collision prevention radars, RFID tags, capacitors, inverter parts, cable covering materials, insulating materials for secondary batteries such as lithium-ion batteries, speaker diaphragms, etc.

[0142] Examples of high-speed communication substrates include base station antenna substrates, antenna distribution substrates, substrates for RRH (Remote Radio Head) wireless components of wireless base stations, substrates for the control unit or baseband unit (BBU) of wireless base stations, high-speed communication transceiver substrates, RNC (Radio Network Controller) substrates, high-speed transmitter substrates, high-speed receiver substrates, high-speed signal multiplexing circuit substrates, WiFig substrates using the 60 GHz band, and data transfer substrates used in data center servers. Other examples of high-speed communication substrates include antenna substrates, such as substrates for massive MIMO (massive multiple-element) antennas for high-capacity communications required by 5G and later standards. Further examples include receiving antennas for microwave-based wireless power transmission. The sheet of the present disclosure has good adhesion to unroughened copper foil, which has low transmission loss. Therefore, when a copper clad laminate containing the sheet of the present disclosure and unroughened copper foil is processed to obtain an antenna, the gain is improved, making it particularly suitable for antennas.

[0143] The sheet of the present disclosure can be used not only as an insulator for circuit boards but also as an insulator for signal line coating, for example, as an insulating coating material (e.g., insulating tube) for waveguides that transmit high-speed signals, QSFP cables for high-speed LANs, coaxial cables for high-speed communication (e.g., SFP+ cables, QSFP+ cables, etc.), and low-loss coaxial cables.

[0144] When using such high frequencies, materials used in electrical components such as connectors and communication devices such as casings are required to have stable electrical properties such as a low relative permittivity (εr) and a low dielectric loss tangent (tanδ). The sheet of the present disclosure can also be used as an insulating material for such materials.

[0145] The sheet of the present disclosure can also be used as an insulating material for connector printed wiring boards that require soldering. Because the sheet of the present disclosure has excellent heat resistance, problems are unlikely to occur even at high temperatures during soldering.

[0146] In dielectric waveguides, materials with low dielectric loss are required to transmit high-frequency millimeter waves or submillimeter waves with low loss. The sheet of the present disclosure can also be used as an insulating material for dielectric waveguides that transmit millimeter waves, submillimeter waves, etc. Examples of dielectric waveguides include cylindrical dielectric waveguides, rectangular dielectric waveguides, elliptical dielectric waveguides, tubular dielectric waveguides, image waveguides, insulator image waveguides, trapped image waveguides, rib guides, strip dielectric waveguides, inverted strip waveguides, H guides, and nonradiative dielectric waveguides (NRD guides).

[0147] In this disclosure, mobility refers to all means and methods related to movement and transportation, including automobiles in general, such as private cars, buses, taxis, and trucks, as well as two-wheeled vehicles such as motorcycles, bicycles, and mopeds, trains, senior cars, and compact one-seater personal mobility vehicles. Furthermore, mobility is not necessarily limited to vehicles that move on land, but may also be vehicles that move in the air or underwater.

[0148] The laminate for a circuit board may be a laminate having a copper foil layer, the above-mentioned sheet, and a base layer. The base layer is not particularly limited, and preferably has a fabric layer made of glass fiber and a resin film layer.

[0149] The glass fiber fabric layer is a layer made of glass cloth, glass nonwoven fabric, or the like. Commercially available glass cloths can be used, and those treated with a silane coupling agent are preferred to enhance affinity with the fluororesin. Examples of glass cloth materials include E glass, C glass, A glass, S glass, D glass, NE glass, and low-dielectric-constant glass, with E glass, S glass, and NE glass being preferred due to their ease of availability. The fiber weave may be plain weave or twill weave. The thickness of the glass cloth is usually 5 to 90 μm, preferably 10 to 75 μm, but it is preferable to use a glass cloth that is thinner than the fluororesin film used.

[0150] The laminate may use a glass nonwoven fabric as a fabric layer made of glass fibers. The glass nonwoven fabric is a fabric in which short glass fibers are fixed with a small amount of a binder compound (resin or inorganic substance), or a fabric in which the shape is maintained by entanglement of the short glass fibers without the use of a binder compound. Commercially available glass nonwoven fabrics can be used. The diameter of the short glass fibers is preferably 0.5 to 30 μm, and the fiber length is preferably 5 to 30 mm. Specific examples of binder compounds include resins such as epoxy resins, acrylic resins, cellulose, polyvinyl alcohol, and fluororesins, as well as inorganic substances such as silica compounds. The amount of binder compound used is usually 3 to 15 mass% based on the weight of the short glass fibers. Examples of materials for the short glass fibers include E-glass, C-glass, A-glass, S-glass, D-glass, NE-glass, and low-dielectric-constant glass. The thickness of the glass nonwoven fabric is usually 50 to 1000 μm, preferably 100 to 900 μm. The thickness of the glass nonwoven fabric in this disclosure refers to a value measured in accordance with JIS P8118:1998 using a digital gauge DG-925 (load 110 grams, face diameter 10 mm) manufactured by Ono Sokki Co., Ltd. The glass nonwoven fabric may be treated with a silane coupling agent to enhance its affinity with the fluororesin.

[0151] Since most glass nonwoven fabrics have a very high porosity of 80% or more, it is preferable to use a sheet that is thicker than a sheet made of fluororesin and compress it under pressure.

[0152] The glass fiber fabric layer may be a layer formed by laminating a glass cloth and a glass nonwoven fabric. This allows the properties of each to be combined to obtain suitable properties. The glass fiber fabric layer may be in the form of a prepreg impregnated with a resin.

[0153] In the laminate, the glass fiber fabric layer and the sheet may be bonded at the interface, or the glass fiber fabric layer may be partially or entirely impregnated with the sheet. Furthermore, a prepreg may be prepared by impregnating a fabric made of glass fiber with a fluororesin composition. The prepreg thus obtained may be further laminated with a fluororesin sheet according to the present disclosure. In this case, the fluororesin composition used to prepare the prepreg is not particularly limited, and the sheet according to the present disclosure may also be used.

[0154] The resin film used as the substrate layer is preferably a heat-resistant resin film or a thermosetting resin film. Examples of heat-resistant resin films include polyimide, modified polyimide, liquid crystal polymer, and polyphenylene sulfide. Examples of thermosetting resins include those containing epoxy resin, bismaleimide, polyphenylene oxide, modified polyphenylene ether, polyphenylene ether, and polybutadiene. The heat-resistant resin film and the thermosetting resin film may contain reinforcing fibers. The reinforcing fibers are not particularly limited, but for example, glass cloth, particularly low-dielectric type, is preferred. The dielectric properties, linear expansion coefficient, water absorption coefficient, and other properties of the heat-resistant resin film and thermosetting resin film are not particularly limited, but for example, the dielectric constant at 20 GHz is preferably 3.8 or less, more preferably 3.4 or less, and even more preferably 3.0 or less. The dielectric loss tangent at 20 GHz is preferably 0.0030 or less, more preferably 0.0025 or less, and even more preferably 0.0020 or less. The linear expansion coefficient is preferably 100 ppm / °C or less, more preferably 70 ppm / °C or less, and even more preferably 40 ppm / °C or less. The water absorption is preferably 1.0% or less, more preferably 0.5% or less, and even more preferably 0.1% or less.

[0155] When the metal clad laminate essentially comprising the above-mentioned sheet and copper foil is laminated with a base layer such as a resin film layer, the lamination can be performed by adhering the sheet layer side of the metal clad laminate to the base layer. In this case, the sheet layer side of the metal clad laminate may be subjected to a surface treatment before lamination to enhance adhesive properties. The surface treatment here is not particularly limited, and examples thereof include the above-mentioned plasma treatment.

[0156] In the laminate, the order in which the copper foil layer, the base material, and the above-mentioned sheets are stacked and the manufacturing method are not particularly limited, and a layer configuration according to the purpose can be adopted. Specific examples of the above-mentioned lamination order include a base material layer / sheet / copper foil layer, a copper foil layer / sheet / base material layer / sheet / copper foil layer, and a copper foil layer / base material layer / sheet / base material layer / copper foil layer. If necessary, other layers may also be included. [Example]

[0157] The present disclosure will be specifically described below based on examples. In the following examples, unless otherwise specified, "parts" and "%" represent "parts by mass" and "% by mass", respectively.

[0158] The spherical silica used in each of the examples and comparative examples is as follows: Admatechs SC6500-SQ (Silica A: average particle size 2.1 μm, dielectric dissipation factor 0.00051) Admatechs SC6500-SQ (average particle size 2.1 μm) treated with 3-aminopropyltriethoxysilane at a treatment amount of 0.2% by mass relative to the mass of silica particles (dielectric tangent 0.00058) Admatechs SC6500-SQ (average particle size 2.1 μm) treated with 3-aminopropyltriethoxysilane at a treatment amount of 1% by mass relative to the mass of silica particles (dielectric tangent 0.00044) Admatechs SC6500-SQ (average particle size 2.1 μm) treated with 3-isocyanatepropyltriethoxysilane at a treatment amount of 0.2% by mass relative to the mass of silica particles (dielectric dissipation factor 0.00052)

[0159] The crushed silica used in each of the examples and comparative examples is as follows. Tatsumori ZA-30 (Silica B: average particle size 5.6 μm, dielectric dissipation factor 0.00838)

[0160] The organosiloxanes used in the examples and comparative examples are as follows: Shin-Etsu Chemical Co., Ltd. KF-96-50CS (polydimethylsilicone oil: PDMS) Shin-Etsu Chemical Co., Ltd. X-22-162C (polydimethylsilicone oil with both ends modified with RCOOH groups) Shin-Etsu Chemical Co., Ltd. KF-8012 (polydimethylsilicone oil with both ends modified with RNH2 groups) Shin-Etsu Chemical Co., Ltd. X-22-168B (polydimethylsilicone oil with both ends modified with carboxylic anhydride groups) Shin-Etsu Chemical Co., Ltd. X-22-2445 (polydimethylsilicone oil with both ends modified with acrylic groups) Shin-Etsu Chemical Co., Ltd. KF-868 (polydimethylsilicone oil with side chains modified with RNH2 groups) Shin-Etsu Chemical Co., Ltd. KF-99 (polydimethylsilicone oil with side chains modified with hydrogen atoms) Shin-Etsu Chemical Co., Ltd. KF-50-100CS (polydimethylsilicone oil with side chains modified with phenyl groups) X-22-822 manufactured by Shin-Etsu Chemical Co., Ltd. (polydimethylsilicone oil with side chains modified with C2H4CF3 groups)

[0161] The fluororesin particles (PTFE) used in each example had the following properties. Average particle size: 500μm Apparent density: 460g / L Standard specific gravity: 2.17

[0162] (Powder rolling molding) Fluororesin particles (PTFE), silica, and organosiloxane were weighed out in the proportions shown in Tables 1 and 2, and stirred twice for 30 seconds at room temperature using a Wonder Crusher at setting 6. The resulting mixture was rolled using two rolls (roll gap: set to 100 μm, roll temperature: 100°C) to obtain a sample with a film thickness of 125 μm, which was then baked at 360°C for 15 minutes to obtain a sheet.

[0163] (Paste extrusion molding) The fluororesin particles (PTFE), silica, and organosiloxane were weighed out in the prescribed amounts in the ratios shown in Table 1 and mixed in a mixer in the presence of dry ice. The temperature during mixing was −10° C. or lower. To the resulting mixed powder, 18 to 23% of oil (IP Solvent 2028) was added, mixed, and aged for about 5 hours. The aged composition was preformed under a pressure of 3 MPa, and the preformed compact was extruded at 40°C and 50 mm / min to obtain an extruded sample. The extruded sample was rolled using two rolls to obtain a sample with a film thickness of 125 μm. This sample was dried at 200°C for 2 hours and calcined at 360°C for 15 minutes to obtain a sheet.

[0164] Each of the obtained samples was evaluated based on the following criteria.

[0165] [Sheet thickness] Measurements were taken using a micrometer.

[0166] [Dielectric constant (Dk) and dissipation factor (Df) of the sheet] The relative permittivity and dielectric loss tangent were measured at 25°C and 10 GHz using a split cylinder type dielectric constant / dielectric loss tangent measuring device (manufactured by EM Lab).

[0167] [Constant humidity test] Each sample was placed in a constant temperature and humidity oven maintained at 30°C and 90% RH, and the change in the dielectric loss tangent after 24 hours was tracked. The rate of increase was calculated using the following formula. Increase rate (%) = (dielectric loss tangent after 24 hours - dielectric loss tangent before humidity test) / dielectric loss tangent before humidity test × 100

[0168] Coefficient of Linear Expansion (CTE) TMA measurements were performed in tensile mode using a TMA-7100 (Hitachi High-Tech Science Corporation). A sheet cut to a length of 20 mm, width of 5 mm, and thickness of 150 μm was used as the sample piece. The distance between the chucks was set to 10 mm, and the linear expansion coefficient was calculated from the displacement of the sample from 0 to 150°C at a heating rate of 2°C / min while applying a load of 49 mN. The results are shown in Tables 1 and 2.

[0169] [Moisture rise value of sheet] Each sample was placed in a constant temperature and humidity oven maintained at 30°C and 90% RH and stored for one week. The samples before and after the humidity test were shredded and placed in the evaporation chamber of a moisture measuring device (Mitsubishi Chemical CA-200, VA-200) to analyze the moisture generated at 250°C. The sheet of Comparative Example 1 had a moisture content of 190 ppm before the constant humidity test and 280 ppm after the constant humidity test. The sheet of Example 1 had a moisture content of 240 ppm before the constant humidity test and 220 ppm after the constant humidity test. The number of significant figures is two.

[0170] [Formaldehyde content in sheets contained in metal clad laminates] The sample was cut into approximately 10 mm squares, sealed in a heating vessel, and heated at 360°C for 30 minutes in the presence of N2 gas. The evolved gas was collected in an adsorption tube and subjected to thermal desorption GC / MS measurement (Markes TD-100 and Agilent GC7890A+5875C). A calibration curve was created from the absolute amount of the standard and the obtained peak area value, and quantification was performed. The sheet of Example 5 generated 220 μg / g of gas and contained cyclic siloxane. The sheet of Example 9 generated 110 μg / g of gas and contained cyclic siloxane.

[0171] [Water absorption test] The test was carried out in accordance with IPC-TM-650 test method 2.6.2.1. The water absorption rate was calculated using the following formula:

number

[0172] The sheet of Example 1 had a water absorption rate of 0.021 wt%. The sheet of Comparative Example 1 had a water absorption rate of 0.195 wt %. The sheet of Example 5 had a water absorption rate of 0.022 wt%. The sheet of Example 6 had a water absorption rate of 0.018 wt%.

[0173] [Surface liquid repellency test] The sheet was immersed in a "wet tension test mixture" manufactured by Wako Pure Chemical Industries, Ltd. for 1 minute at room temperature, then washed with distilled water, and visually inspected to see if the wet tension test mixture had penetrated into the sheet. Wet tension test mixtures No. 22.6 to 70.0 were used, and the value of the test liquid with the lowest surface tension among the wet tension test mixtures that showed no penetration was taken as the critical liquid repellency result. The sheet of Example 1 had a critical liquid repellent tension of 22.6 mN / M. The sheet of Comparative Example 1 had a critical liquid repellent tension of 22.6 mN / M. The sheets of Comparative Example 1 and Example 1 had the same surface liquid repellency tension, but in terms of water absorption, the sheet of Comparative Example 1 was insufficient. The composition of the present disclosure can also reduce water absorption.

[0174] [Table 1]

[0175] [Table 2]

[0176] From the above results, the sheet of the present disclosure has excellent performance in terms of suppressing water absorption and moisture absorption under high humidity conditions and suppressing an increase in dielectric loss tangent. [Industrial Applicability]

[0177] The sheet of the present disclosure can be suitably used in particular for circuit boards, especially high-frequency printed circuit boards.

Claims

1. A composition comprising fluororesin particles, inorganic particles, and a modified organosiloxane, wherein the modified organosiloxane accounts for 0.05% by mass or more and 2% by mass or less of the entire composition, and components other than the fluororesin particles, inorganic particles, and modified organosiloxane account for 10% by mass or less of the composition, and the modified organosiloxane has at least one group selected from the group consisting of a hydrogen atom, an amino group, an epoxy group, a mercapto group, a carboxyl group, an acrylic group, a methacrylic group, a carboxylic anhydride group, an alkyl group other than a methyl group, an aralkyl group, a fluoroalkyl group, a perfluoroalkyl group, an ester group, an amide group, and a phenyl group at any or all of its side chains, one end, and both ends.

2. 2. The composition according to claim 1, wherein the inorganic particles are inorganic particles containing silica as an essential component.

3. 3. The composition according to claim 1, wherein the fluororesin particles are perfluororesin particles.

4. 4. The composition according to claim 3, wherein the perfluororesin is polytetrafluoroethylene.

5. The composition of claim 2, wherein said silica is spherical silica.

6. The composition according to claim 2, wherein the silica has a dielectric loss tangent of 0.0025 or less at 10 GHz.

7. 3. The composition according to claim 1, wherein the inorganic particles are coated with a silane coupling agent.

8. 3. The composition according to claim 1, wherein the content of the inorganic particles is 40% by mass or more of the total composition.

9. 3. The composition according to claim 1, wherein the inorganic particles have an average particle size of 0.5 μm or more.

10. The viscosity of the modified organosiloxane is 3 to 18,000 mm ２ 3. The composition according to claim 1, wherein the viscosity is 1000 MPa (25°C).

11. The composition according to claim 1 or 2, wherein the modified organosiloxane has at least one group selected from the group consisting of a hydrogen atom, an amino group, a carboxyl group, an acrylic group, a carboxylic anhydride group, an alkyl group other than a methyl group, a fluoroalkyl group, a perfluoroalkyl group, an ester group, an amide group, and a phenyl group at any or all of its side chains, one end, and both ends.

12. The composition according to claim 1 or 2, wherein the modified organosiloxane has at least one group selected from the group consisting of a hydrogen atom, an amino group, a carboxyl group, an acrylic group, a fluoroalkyl group, a phenyl group, and a carboxylic anhydride group at any one of a side chain, one terminal, and both terminals thereof.

13. the fluororesin particles are polytetrafluoroethylene, the inorganic particles are silica, The content of the inorganic particles is 50% by mass or more and 70% by mass or less, The composition according to claim 1, wherein the modified organosiloxane is at least one selected from the group consisting of methylhydrogenpolysiloxane, methylphenylpolysiloxane, carboxyl-modified polysiloxane, amino-modified polysiloxane, acrylic-modified polysiloxane, carboxylic anhydride-modified polysiloxane, and fluoroalkyl group-modified polysiloxane.

14. A sheet comprising the composition according to claim 1 or 2.

15. 15. The sheet according to claim 14, wherein the increase in moisture content after storage for one week in an environment of 30°C and 90% RH is 60 ppm or less.

16. 15. The sheet according to claim 14, wherein the increase in dielectric tangent when stored for 24 hours in an environment of 30°C and 90% RH is 30% or less.

17. 15. The sheet according to claim 14, having a coefficient of linear expansion (CTE) of 200 ppm / K or less.

18. 15. A method for producing the sheet according to claim 14, comprising molding a composition obtained by mixing fluororesin particles, inorganic particles, and a modified organosiloxane.

19. The method for producing a sheet according to claim 18, wherein molding is performed using a composition consisting essentially of fluororesin particles, inorganic particles, and modified organosiloxane.

20. A metal clad laminate comprising a metal layer and the sheet according to claim 14 as essential layers.

21. 21. The metal clad laminate according to claim 20, wherein the sheet contained in the metal clad laminate contains at least one selected from the group consisting of formaldehyde, formic acid, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane.

22. The metal clad laminate according to claim 20, wherein the metal layer is a copper foil.

23. A circuit board comprising the metal clad laminate according to claim 20.

Images