Thermosetting resin sheet, method for manufacturing same, printed wiring board, and semiconductor device

Abstract

Provided are: a thermosetting resin sheet that has favorable wiring embedding properties while ensuring insulation properties and can maintain a low dielectric constant and a low dielectric loss tangent; a method for manufacturing the same; and a printed wiring board and a semiconductor device which use the same. Provided are: a thermosetting resin sheet having a first surface disposed on a substrate side and a second surface facing the first surface, and containing hollow inorganic particles, wherein when a metal element and a metalloid element are M, the ratio of the C / Si element molar ratio of the first surface to the C / M element molar ratio of the second surface is 1.02-1.09, and the thickness of said thermosetting resin sheet is 10-150 μm; a method for manufacturing the same; and a printed wiring board and a semiconductor device which use said thermosetting resin sheet.

Description

Thermosetting resin sheet and method for manufacturing the same, printed circuit board and semiconductor device

[0001] This disclosure relates to thermosetting resin sheets, methods for manufacturing the same, printed circuit boards, and semiconductor devices.

[0002] In recent years, to reduce transmission loss in high-speed communications, interlayer insulating films used in printed circuit boards are required to have not only insulating properties but also low dielectric constant and low dielectric loss tangent.

[0003] Patent Document 1 discloses an insulating film using a resin composition containing a specific amount of hollow silica.

[0004] Japanese Patent Publication No. 2013-173841

[0005] While incorporating hollow inorganic particles into a resin layer can lower the dielectric constant and dielectric loss tangent, depending on the dispersion state (arrangement) of the hollow inorganic particles in the resin layer, partial discharge may occur within the hollow inorganic particles when a voltage difference is applied between the front and back surfaces of the resin layer, potentially reducing interlayer insulation. Furthermore, if the hollow inorganic particles in the resin layer are unevenly dispersed towards the wiring substrate side, their embedding ability into the wiring may decrease.

[0006] This disclosure has been made in view of the above-mentioned problems, and aims to provide a thermosetting resin sheet that ensures insulation, has good wiring embedding properties, and maintains low dielectric constant and low dielectric loss tangent, as well as a method for manufacturing the same, and a printed circuit board and semiconductor device using the thermosetting resin sheet.

[0007] The thermosetting resin sheet and its manufacturing method, as well as the printed circuit board and semiconductor device related to this disclosure, are as shown in [1] to

[19] below. [1] A thermosetting resin sheet having a first surface disposed on the substrate side and a second surface facing the first surface, containing hollow inorganic particles, and with metal elements and metalloid elements as M, the ratio of the C / M element molar ratio of the first surface to the C / M element molar ratio of the second surface is 1.02 to 1.09, and the thickness is 10 to 150 μm. [2] The thermosetting resin sheet according to [1], wherein the C / M element molar ratio of the second surface is 3.2 to 6.8. [3] The thermosetting resin sheet according to [1] or [2], wherein the C / M element molar ratio of the first surface is 3.3 to 7.2. [4] The thermosetting resin sheet according to any one of [1] to [3], wherein the dielectric constant at a frequency of 10 GHz is less than 2.6. [5] A thermosetting resin sheet according to any one of [1] to [4], wherein the dielectric loss tangent at a frequency of 10 GHz is 0.004 or less. [6] A thermosetting resin sheet according to any one of [1] to [5], wherein the hollow inorganic particles contain an inorganic oxide containing one or more selected from aluminum, magnesium, silicon, titanium, and zinc. [7] A thermosetting resin sheet according to any one of [1] to [6], wherein the hollow inorganic particles contain silica. [8] A thermosetting resin sheet according to any one of [1] to [7], wherein the content of the hollow inorganic particles is 12 to 27% by mass. [9] A thermosetting resin sheet according to any one of [1] to [8], wherein the average particle size of the hollow inorganic particles is 0.4 μm or more and 3.0 μm or less.

[10] A thermosetting resin sheet according to any one of [1] to [9], wherein the angle of repose of the hollow inorganic particles is 45° or more and 60° or less.

[11] A thermosetting resin sheet according to any one of [1] to

[10] , further comprising solid inorganic particles.

[12] A thermosetting resin sheet according to any one of [1] to

[11] , wherein the content of the solid inorganic particles is 17 to 37% by mass.

[13] A method for producing a thermosetting resin sheet, comprising coating a resin composition containing hollow inorganic particles onto a substrate, drying it so that the common logarithm LogPe of the Peclet number Pe calculated by the following formula 1 is 3.0 to 5.0, and producing a thermosetting resin sheet with a thickness of 10 to 150 μm, wherein the ratio of the molar ratio of the C / M elements of the first surface to the molar ratio of the C / M elements of the second surface facing the first surface on the substrate side is 1.02 to 1.09, when M is the amount of metallic and metalloid elements. (Formula 1) Pe = (6πμEHR) / (kT) μ: Initial viscosity of the particle-free resin composition (Pa·s) E: Film shrinkage rate (m / s) H: Wet film thickness (m) R: Average particle size of hollow inorganic particles (m) k: Boltzmann constant (J / K) T: Liquid temperature (K)

[14] The method for producing a thermosetting resin sheet according to

[13] , wherein the drying temperature during the drying is 60°C or more and 150°C or less.

[15] The method for producing a thermosetting resin sheet according to

[13] or

[14] , wherein the wind speed during the drying is 1 m / s or more and 8 m / s or less.

[16] The method for producing a thermosetting resin sheet according to any one of

[13] to

[15] , wherein the resin composition contains a solvent, and the solvent is a mixed solvent containing toluene and a second solvent other than toluene.

[17] The method for producing a thermosetting resin sheet according to

[16] , wherein the relative evaporation rate of the mixed solvent is 1.0 or more and 4.5 or less. A printed circuit board comprising a thermosetting resin sheet as described in any of

[18] [1] to

[12] . A semiconductor device comprising a printed circuit board as described in

[19]

[18] .

[0008] This disclosure provides a thermosetting resin sheet that ensures insulation, has good embedding properties for wiring, and maintains a low dielectric constant and low dielectric loss tangent, as well as a method for manufacturing the same, and a printed circuit board and a semiconductor device using the thermosetting resin sheet.

[0009] In this specification, numerical ranges indicated using "~" include the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages within this specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in numerical ranges described within this specification, the upper or lower limit of that range may be replaced with the values ​​shown in the examples.

[0010] In the insulating film described in Patent Document 1, increasing the content of hollow silica can reduce the dielectric constant and dielectric loss tangent, but it can be difficult to achieve both embedding properties for fine wiring and interlayer insulation.

[0011] As a result of diligent investigation, the inventors hypothesized that, due to the difference in discharge ease between hollow inorganic particles and resin, partial discharge occurs within the hollow inorganic particles when a voltage difference is applied to the front and back surfaces of the resin layer, leading to a decrease in insulation performance. Furthermore, the inventors hypothesized that if the hollow inorganic particles are unevenly distributed towards the wiring substrate, the embedding ability of the resin sheet into the wiring substrate may decrease. Based on these hypothesis, the inventors found that by satisfying the following configuration, they could provide an excellent thermosetting resin sheet that satisfies all requirements for insulation, embedding ability, dielectric constant, and dielectric loss tangent. Specifically, the inventors found that the above effect can be obtained by a thermosetting resin sheet having a specific thickness in which the ratio of the C / M element molar ratio of the first surface to the C / M element molar ratio of the second surface facing the first surface on the substrate side is within a specific range. Hereinafter, M represents the total amount of metallic elements and metalloid elements. The metalloid elements include B, Si, As, Te, At, Ge, Sb, and Po.

[0012] The embodiments of the thermosetting resin sheet (hereinafter also referred to as "the sheet") relating to this disclosure will be described in detail below, but this disclosure is not limited to these embodiments. The sheet may be in its pre-curing state or in its post-curing state. In other words, the sheet may include thermosetting resin sheets in both pre- and post-curing states. However, in the following description, when "the sheet" is used, it basically refers to the thermosetting resin sheet after curing. Furthermore, the disclosure can be modified and implemented as desired without departing from the gist of this disclosure.

[0013] <Thermosetting resin sheet> This sheet has a first surface that is positioned on the substrate side and a second surface that is opposite to the first surface, and contains hollow inorganic particles, and the ratio of the molar ratio of the C / M elements of the first surface to the molar ratio of the C / M elements of the second surface (hereinafter also referred to as the relative C / M ratio) is 1.02 to 1.09, and the thickness is 10 to 150 μm.

[0014] In this sheet, the substrate and the first surface of the sheet may be in contact, or there may be another layer between the substrate and the first surface. On the second surface of the sheet, for example, a protective film may be provided to protect the sheet. This protective film may be in contact with the second surface of the sheet, or there may be another layer between the protective film and the second surface. The sheet may be handled in the form of, for example, a substrate and a thermosetting resin sheet (resin composition layer). Alternatively, it may be handled in the form of a thermosetting resin sheet (resin composition layer) and a protective film. Furthermore, it may be handled in the form of a substrate, a thermosetting resin sheet (resin composition layer), and a protective film. In other words, the sheet may include one composed only of a resin composition layer. The sheet may also include one in which a resin composition layer is provided on a substrate. The sheet may also include one in which a protective film is provided on a resin composition. Furthermore, the sheet may include one in which a substrate, a resin composition layer, and a protective film are laminated in this order. When the sheet is used in printed circuit boards or semiconductor devices, the second surface of the sheet can be placed on the circuit board side. The base material and protective film will be described later.

[0015] (Hollow Inorganic Particles) This sheet contains hollow inorganic particles. By adding hollow inorganic particles to a thermosetting resin sheet, electrical properties such as dielectric constant Dk and dielectric loss tangent Df are improved. Examples of inorganic particles used in the hollow inorganic particles include silicon oxide (silica), metal oxides (beryllium oxide, cerium oxide, aluminum oxide (alumina), soda-alumina, magnesium oxide, zinc oxide, titanium oxide, lead oxide, nickel oxide, cobalt oxide, copper oxide, zirconium oxide, iron oxide, lithium oxide, barium oxide, potassium oxide, calcium oxide, boron oxide, sodium oxide, etc.), boron nitride, and magnesium metasilicate (steatite). Among these, from the viewpoint of electrical properties, inorganic particles in the hollow inorganic particles are preferably inorganic particles containing inorganic oxides that contain at least one element selected from aluminum, magnesium, silicon, titanium, and zinc, and inorganic particles containing silica (hollow silica particles) are particularly preferred. For example, this sheet may be implemented by substituting "hollow inorganic particles" with "hollow silica particles" in the following description. The hollow inorganic particles may also be composed of a composite inorganic oxide containing multiple inorganic oxides. One type of hollow inorganic particle may be used alone, or multiple types may be used in combination. However, when multiple types of hollow inorganic particles are used, it is preferable that the entire set of hollow inorganic particles satisfies the following conditions.

[0016] From the viewpoint of electrical properties, the total content of metallic and metalloid elements in the hollow inorganic particles is preferably 20 to 80% by mass, more preferably 25 to 75% by mass, and even more preferably 30 to 70% by mass.

[0017] Hollow inorganic particles are silica (SiO ２ If it contains ), the content is preferably 70% by mass or more, more preferably 75% by mass or more, and even more preferably 80% by mass or more, from the standpoint of obtaining a sheet with low dielectric constant and low dielectric loss tangent, and the hollow inorganic particles may consist only of silica. Furthermore, the silica content in the hollow inorganic particles is preferably 99% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less, and particularly preferably 85% by mass or less, from the standpoint of obtaining a sheet with low dielectric constant and low dielectric loss tangent.

[0018] In addition to the above, hollow inorganic particles may also include, for example, the following inorganic materials: glass, cordierite, silicon oxide, barium sulfate, barium carbonate, talc, clay, mica powder, zinc oxide, hydrotalcite, boehmite, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, aluminum nitride, manganese nitride, aluminum borate, strontium carbonate, strontium titanate, calcium titanate, magnesium titanate, bismuth titanate, barium titanate, barium zirconate titanate, barium zirconate, calcium zirconate, zirconium phosphate, zirconium tungstate phosphate, aluminosilicate, etc.

[0019] From the viewpoint of electrical properties, the shape of the hollow inorganic particles is more preferably spherical, and particularly preferably perfectly spherical.

[0020] The porosity of the hollow inorganic particles can be selected as appropriate and is not particularly limited, but is preferably 5 vol% or more, more preferably 10 vol% or more, even more preferably 15 vol% or more, even more preferably 20 vol% or more, particularly preferably 25 vol% or more, even more preferably 30 vol% or more, extremely preferably 40 vol% or more, and most preferably 50 vol% or more. If the porosity is at the above percentages, sufficient voids are contained, and the dielectric constant tends to decrease. Furthermore, the porosity of the hollow inorganic particles is preferably 90 vol% or less, more preferably 85 vol% or less, and even more preferably 80 vol% or less. If the porosity is at the above percentages, the strength of the shell of the hollow inorganic particles is high and they are less prone to breakage.

[0021] The porosity of hollow inorganic particles represents the volume percentage of the hollow portion within the hollow inorganic particles. This porosity can be calculated from the density of the hollow inorganic particles. Specifically, the density of the hollow inorganic particles to be measured is measured using a true density analyzer. Specifically, nitrogen is used as the measuring gas, and the true density analyzer is, for example, the ULTRAPYCNOMETER 1000 (product name) manufactured by QUANTACH ROME. Then, using the measured density and the material density of the inorganic material forming the hollow inorganic particles, the porosity is calculated according to the following Equation 2: (Equation 2) Porosity (volume %) = {1 - (measured density [g / cm³]) ３ ] / Material density of inorganic materials [g / cm³] ３ ])} × 100

[0022] The average particle size of the hollow inorganic particles is not particularly limited, but from the viewpoint of insulating properties, it is preferably 0.01 μm or more, more preferably 0.05 μm or more, even more preferably 0.1 μm or more, even more preferably 0.2 μm or more, especially preferably 0.3 μm or more, and extremely preferably 0.4 μm or more. Furthermore, from the viewpoint of embedding properties, the average particle diameter of the hollow inorganic particles is preferably 10 μm or less, more preferably 5.0 μm or less, even more preferably 4.0 μm or less, even more preferably 3.0 μm or less, especially preferably 2.5 μm or less, even more preferably 2.0 μm or less, extremely preferably 1.6 μm or less, and most preferably 1.0 μm or less. From the viewpoint of electrical properties, the average particle size of the hollow inorganic particles is preferably 0.4 μm or more and 3.0 μm or less.

[0023] In this specification, the average particle size of hollow inorganic particles refers to the 50% particle size (D50). The 50% particle size (D50) can be determined using a laser diffraction particle size distribution analyzer (e.g., Microtrac-Bell Co., Ltd., product name "MT3300EXII") or an electrical detection method (Coulter counter method) particle size distribution analyzer (e.g., Beckman Coulter, product name "Multisizer4e").

[0024] The BET specific surface area of ​​hollow inorganic particles is 100 m² from the standpoint of electrical properties. ２ Preferably less than / g, and 80m ２More preferably less than / g, and 50m ２ A value of less than or equal to / g is even more preferable. Here, the BET specific surface area can be measured, for example, using the "Tristar II 3020" specific surface area measuring device (product name) manufactured by Shimadzu Corporation, after pretreatment by drying at 230°C until it reaches 50 mTorr, and then measuring using a multi-point method with liquid nitrogen.

[0025] The shell thickness of hollow inorganic particles is preferably 0.01 to 0.3, more preferably 0.02 to 0.2, and even more preferably 0.03 to 0.1, relative to the size of the (primary) particles. If the shell thickness of the hollow inorganic particles is 0.01 or more relative to the particle size, the hollow inorganic particles can easily have good strength. Furthermore, if this ratio is 0.3 or less, the size of the internal voids can be easily adjusted to an appropriate size, and the properties due to the hollow shape can be easily exhibited. Here, the shell thickness can be determined by measuring the shell thickness of individual particles by TEM (transmission electron microscope) observation.

[0026] The angle of repose of hollow inorganic particles is the angle between the slope of the powder mound formed when a powder consisting of hollow inorganic particles is dropped from a certain height and remains stable without spontaneously collapsing, and the horizontal plane. This angle of repose is a parameter that collectively represents the physical friction caused by the shape of the powder and the interactions (between particles) due to chemical attraction, etc. A higher angle of repose indicates greater interaction between particles. The angle of repose of hollow inorganic particles is preferably 45° to 60°, and more preferably 48° to 58°. When the angle of repose of hollow inorganic particles is 45° to 60°, it is easier to adjust the drying process when drying a resin composition (varnish) containing hollow inorganic particles, and the gentle interaction between the hollow inorganic particles makes it easier for them to float to the surface of the coating film, resulting in slight uneven distribution. As a result, it is easier to adjust the composition of the thermosetting resin sheet within the relative C / M ratio range mentioned above. The angle of repose of hollow inorganic particles can be measured, for example, using a multi-functional powder property analyzer MT-02 (product name, manufactured by Seishin Corporation). The method for adjusting the angle of repose will be described later.

[0027] The content of hollow inorganic particles in this sheet (solid content) can be set as appropriate and is not particularly limited, but from the viewpoint of electrical properties, 12% by mass or more is preferred, 13% by mass or more is more preferred, 15% by mass or more is even more preferred, and 17% by mass or more is particularly preferred. Furthermore, from the viewpoint of wiring embedding and insulation properties, the content of hollow inorganic particles in this sheet is preferably 27% by mass or less, more preferably 25% by mass or less, even more preferably 24% by mass or less, even more preferably 23% by mass or less, and particularly preferred to be 20% by mass or less.

[0028] (C / M element molar ratio) In this sheet, the ratio of the C / M element molar ratio of the first surface to the C / M element molar ratio of the second surface is 1.02 to 1.09. If the relative C / M ratio is less than 1.02, the effect of interlayer insulation decreases. On the other hand, if the relative C / M ratio is greater than 1.09, the embedding ability of wiring decreases. From the viewpoint of interlayer insulation, the relative C / M ratio in this sheet is preferably 1.03 or higher, more preferably 1.04 or higher, and particularly preferably 1.05 or higher. Also, from the viewpoint of embedding ability of wiring, the relative C / M ratio is preferably 1.085 or lower, and more preferably 1.080 or lower. The method for measuring the C / M element molar ratio of each surface will be described later.

[0029] The molar ratio of C / M elements on the second surface of this sheet is preferably 3.2 or higher, more preferably 3.3 or higher, even more preferably 3.5 or higher, and particularly preferably 4.0 or higher, from the viewpoint of wiring embedding properties. Furthermore, the molar ratio of C / M elements on the second surface is preferably 6.8 or lower, more preferably 6.78 or lower, and even more preferably 6.75 or lower, from the viewpoint of electrical properties.

[0030] The molar ratio of C / M elements on the first surface of this sheet is preferably 3.3 or higher, more preferably 3.35 or higher, even more preferably 3.4 or higher, and particularly preferably 4.0 or higher, from the viewpoint of wiring adhesion. Furthermore, the molar ratio of C / M elements on the first surface is preferably 7.2 or lower, more preferably 7.18 or lower, and even more preferably 7.15 or lower, from the viewpoint of insulation between wirings.

[0031] (Dielectric Constant) The dielectric constant Dk of this sheet at a frequency of 10 GHz is preferably less than 2.6, more preferably 2.5 or less, even more preferably 2.4 or less, even more preferably 2.3 or less, and particularly preferably 2.2 or less, from the viewpoint of application to high-speed communication. The method for measuring the dielectric constant will be described later.

[0032] (Dielectric Loss Tangent) The dielectric loss tangent Df of this sheet at a frequency of 10 GHz is preferably 0.004 or less, more preferably 0.003 or less, even more preferably 0.0025 or less, and particularly preferably 0.002 or less, from the viewpoint of application to high-speed communication. The method for measuring the dielectric loss tangent will be described later.

[0033] (Thickness) The thickness of this sheet is 10 to 150 μm. From the viewpoint of practical application, the thickness of this sheet should be 10 μm or more. Furthermore, if the thickness of this sheet is 150 μm or less, thinning of printed circuit boards and semiconductor packages can be achieved. From the viewpoint of interlayer insulation, the thickness of this sheet is preferably 12 μm or more, more preferably 15 μm or more, and even more preferably 20 μm or more. From the viewpoint of thinning, the thickness of this sheet is preferably 100 μm or less, more preferably 60 μm or less, even more preferably 40 μm or less, and particularly preferably 30 μm or less.

[0034] (Other materials) In addition to the hollow inorganic particles mentioned above, this sheet may contain thermosetting resins, and may also contain additives such as elastomers, other inorganic particulate materials, crosslinking agents (curing agents), flame retardants, radical initiators, and silane coupling agents. The content of each additive can be set as appropriate and is not particularly limited.

[0035] The thermosetting resin can be any resin conventionally known in the field of printed circuit boards, etc., and is not particularly limited. Examples of thermosetting resins include phenolic resins, polyphenylene ether resins, epoxy resins, polyfunctional cyanate ester resins; maleimide resins such as aromatic maleimide, polyfunctional maleimide, and polyfunctional maleimide-cyanate ester resins; vinyl group-containing resins such as ortho-divinylbenzene resins; unsaturated polyester resins, diallyl phthalate resins, urea resins, melamine resins, guanamine resins, and melamine-urea cocondensation resins. Among these, polyphenylene ether resins, epoxy resins, vinyl group-containing resins, or maleimide resins are preferred as the thermosetting resin. The content of the thermosetting resin in the sheet (solid content) is not particularly limited as long as the effects of this disclosure can be obtained, and can be set appropriately with reference to the prior art. The content of the thermosetting resin in the sheet can be, for example, 51 to 70% by mass.

[0036] Examples of elastomers include styrene-based elastomers such as polystyrene-polybutadiene block copolymer and polystyrene-polyisoprene block copolymer, as well as 1,2-polybutadiene, 1,4-polybutadiene, maleic acid-modified polybutadiene, acrylic acid-modified polybutadiene, and epoxy-modified polybutadiene.

[0037] The shape of the other inorganic material may be, for example, granular, needle-shaped (fibrous), or plate-shaped. More specific shapes of the inorganic material include, for example, spherical, flaky, layered, plate-shaped, leaf-shaped, almond-shaped, columnar, comb-shaped, equiaxed, leaf-shaped, mica-like, block-shaped, plate-shaped, wedge-shaped, rosette-shaped, network-shaped, and prismatic. However, from the viewpoint of electrical properties, the shape of the other inorganic material is more preferably spherical, and particularly preferably perfectly spherical. Examples of such other inorganic materials include inorganic particles other than hollow inorganic particles. It is preferable to use solid inorganic particles as the other inorganic particles.

[0038] As the material of other inorganic materials, those similar to those exemplified in the hollow inorganic particles can be mentioned. Among them, it is preferable to contain silicon, and more preferably to contain silica. Examples of the inorganic material containing silica include on-scale silica, fumed silica, solid spherical silica, crushed silica, etc. Among them, solid spherical silica is preferable in that it is difficult to increase the melt viscosity. The average particle diameter of the solid spherical silica is not particularly limited, but from the viewpoints of embedding property and insulation property, 20 μm or less is preferable, 10 μm or less is more preferable, 5 μm or less is further preferable. The lower limit is not particularly limited, but 0.1 μm or more is preferable.

[0039] When using solid inorganic particles, the content of the solid inorganic particles in this sheet (solid content) is not particularly limited, but for example, it can be 17 to 37% by mass. Also, from the viewpoints of embedding property and insulation property, the total content of the hollow inorganic particles and the solid inorganic particles in this sheet (solid content) is preferably 49% by mass or less, more preferably 48% by mass or less, further preferably 47% by mass or less, still more preferably 46% by mass or less, particularly preferably 45% by mass or less, and extremely preferably 44% by mass or less. Also, from the viewpoint of electrical characteristics, the total content of the hollow inorganic particles and the solid inorganic particles in this sheet is preferably 29% by mass or more, more preferably 30% by mass or more, further preferably 32% by mass or more, and particularly preferably 34% by mass or more.

[0040] Examples of the crosslinking agent include polyfunctional vinyl compounds such as divinylbenzene, divinylnaphthalene, divinylbiphenyl; vinylbenzyl ether compounds synthesized from the reaction of phenol and vinylbenzyl chloride; allyl ether compounds synthesized from the reaction of styrene, phenol and allyl chloride; polyfunctional acrylic compounds having two or more acryloyl groups or methacryloyl groups in the molecule; trialkenyl isocyanurates such as triallyl isocyanurate (TAIC) and triallyl cyanurate (TAC).

[0041] As the flame retardant, for example, a phosphorus-based flame retardant containing at least one compound selected from the group consisting of phosphate esters such as condensed phosphate esters and cyclic phosphate esters, cyclic phosphazene compounds, metal phosphinates such as aluminum dialkylphosphinate; halogen-based flame retardants such as brominated flame retardants can be mentioned.

[0042] As the radical initiator, for example, α,α'-bis(t-butylperoxy-m-isopropyl)benzene (alias: 1,3-bis(butylperoxyisopropyl)benzene), 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, benzoyl peroxide, 3,3',5,5'-tetramethyl-1,4-diphenoquinone, chloranil, 2,4,6-tri-t-butylphenoxyl, t-butylperoxyisopropyl monocarbonate, azobisisobutyronitrile can be mentioned.

[0043] As the silane coupling agent, for example, 3-aminopropyltriethoxysilane, vinyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-isocyanatopropyltriethoxysilane can be mentioned.

[0044] (Base material) The base material (support) disposed on the first surface side of this sheet can be a conventionally well-known one and is not particularly limited. For example, a thermoplastic resin film, a metal foil, or a release paper can be used. Among these, as the base material, it is preferable to use a thermoplastic resin film or a metal foil.

[0045] When using a thermoplastic resin film as a base material, examples of thermoplastic resins include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), acrylics such as polycarbonate (PC) and polymethyl methacrylate (PMMA), cyclic polyolefins, triacetylcellulose (TAC), polyether sulfide (PES), polyether ketones, and polyimides. Among these, polyethylene terephthalate and polyethylene naphthalate are preferred, and inexpensive polyethylene terephthalate is particularly preferred.

[0046] When using metal foil as a base material, examples of metal foil include copper foil and aluminum foil, with copper foil being preferred. As for copper foil, foil made of single-metal copper may be used, or foil made of an alloy of copper with another metal (for example, tin, chromium, silver, magnesium, nickel, zirconium, silicon, titanium, etc.) may be used.

[0047] The substrate may have a matte finish, corona treatment, or antistatic treatment applied to the surface on which the resin composition layer is placed (for example, the surface to be bonded). Alternatively, a substrate with a release layer on the surface on which the resin composition layer is placed may be used. Examples of release agents used in the release layer of a substrate with a release layer include one or more release agents selected from the group consisting of alkyd resins, polyolefin resins, urethane resins, and silicone resins. Commercially available substrates with a release layer may be used, for example, PET films having a release layer mainly composed of an alkyd resin-based release agent, such as Film Vina from Fujimori Industries, Ltd., AL-5 from Lintec Corporation, and Therapiel from Toray Industries, Inc. (all are trade names).

[0048] The thickness of the substrate is not particularly limited, but is preferably 5 μm to 75 μm, and more preferably 10 μm to 60 μm. When using a substrate with a release layer, it is preferable that the overall thickness of the substrate with the release layer is within the above range.

[0049] When using metal foil as the base material, a metal foil with a support substrate may be used, which is formed by laminating a peelable support substrate onto a thin metal foil. In one embodiment, the metal foil with a support substrate may include a support substrate, a release layer provided on the support substrate, and a metal foil provided on the release layer. When using metal foil with a support substrate as the base material, the resin composition layer is provided on the metal foil.

[0050] In a metal foil with a support substrate, the material of the support substrate is not particularly limited, but examples include copper foil, aluminum foil, stainless steel foil, titanium foil, copper alloy foil, etc. When copper foil is used as the support substrate, it may be electrolytic copper foil or rolled copper foil. Furthermore, the release layer is not particularly limited as long as it can be peeled off the metal foil from the support substrate, and examples include an alloy layer of elements selected from the group consisting of Cr, Ni, Co, Fe, Mo, Ti, W, and P, an organic coating, etc.

[0051] In a metal foil with a support substrate, the material of the metal foil is preferably, for example, copper foil or copper alloy foil.

[0052] In a metal foil with a support substrate, the thickness of the support substrate is not particularly limited, but is preferably 10 μm to 150 μm, and more preferably 10 μm to 100 μm. The thickness of the metal foil may also be, for example, 0.1 μm to 10 μm.

[0053] (Protective Film) Any conventionally known protective film can be used as appropriate, and there are no particular limitations. The thickness of the protective film is not particularly limited, but for example, it is 1 μm to 40 μm. By laminating the protective film on the resin composition layer, the adhesion of dust and other debris and scratches to the surface of the resin composition layer can be easily suppressed. The thermosetting resin sheet according to this disclosure may further include any additional layer as needed.

[0054] <Method for Manufacturing Thermosetting Resin Sheets> The method for manufacturing thermosetting resin sheets according to this disclosure (hereinafter also referred to as this manufacturing method) involves coating a resin composition (resin varnish) containing hollow inorganic particles onto a substrate and drying it so that the common logarithm LogPe of the Peclet number Pe calculated by the following formula 1 is 3.0 to 5.0. Then, a thermosetting resin sheet with a thickness of 10 to 150 μm and a relative C / M ratio of 1.02 to 1.09 is produced. In the following description, we will focus on the characteristic parts of this manufacturing method, but for other parts, conventionally known methods for manufacturing thermosetting resin sheets can be applied as appropriate.

[0055] (Equation 1) Pe (Pecule number) = (6πμEHR) / (kT) μ: Initial viscosity of particle-free resin composition (dispersion medium) (Pa·s) E: Film shrinkage rate (m / s) H: Wet film thickness (m) R: Average particle size of hollow inorganic particles (m) k: Boltzmann constant (J / K) T: Liquid temperature (K) Here, film shrinkage rate is the rate at which the thickness of a film containing solvent decreases until it becomes a film containing almost no solvent, and in this specification it is used with the same meaning as drying rate. Specifically, the film shrinkage rate is calculated by the following Equation 3. (Equation 3) Film shrinkage rate [m / s] = (Wet film thickness [m] - Final film thickness [m]) / Drying time [s] Also, the Boltzmann constant is 1.38 × 10 －２３ That is the case.

[0056] Furthermore, when a dispersion containing particles (in this case, a resin composition containing hollow inorganic particles) is applied and dried, the distribution of particles changes depending on the ratio of the film reduction rate during drying, the diffusion motion of the particles, and the settling rate of the particles (see "All About Converting," pp. 179-180, Processing Technology Research Association). These can be expressed by a parameter called the (dry) Peclet number, represented by Equation 1 above, and by setting the common logarithm LogPe to the predetermined range mentioned above, the segregation of hollow inorganic particles can be easily controlled. In other words, by adjusting LogPe, the molar ratio of C / M elements and the relative C / M ratio of each surface can be adjusted.

[0057] Methods for drying resin compositions include, for example, drying by blowing air to evaporate the solvent through stagnation, and drying by directly heating the resin varnish with radiant heat such as infrared rays to evaporate the solvent. Methods for drying by blowing air include a parallel flow method in which air is blown parallel to the direction of travel of the substrate coated with the resin varnish, a counterflow method in which air is blown opposite to the direction of travel of the substrate, a two-dimensional nozzle method in which a jet of air is blown perpendicular to the substrate and directly onto the coating film, and a method in which air is blown from the opposite side of the substrate from the coating film. From the viewpoint of being able to easily adjust the drying speed, drying by blowing air is preferred, and among these, the parallel flow method and the two-dimensional nozzle method are preferred. The drying speed is proportional to the boundary film heat transfer coefficient of the coating film during drying and inversely proportional to the latent heat of vaporization of the solvent. The boundary film heat transfer coefficient is proportional to the wind speed and nozzle size during drying, so the drying speed can be easily controlled by controlling these factors. Multiple methods may be combined for drying.

[0058] The drying temperature can be adjusted as appropriate by the solvent in the resin varnish, but it is preferably 60°C to 150°C, and more preferably 80°C to 120°C. If the drying temperature is 150°C or lower, it is easy to prevent crosslinking agents and other substances contained in the resin composition from starting to react, and it is easy to adjust the viscosity of the thermosetting resin sheet.

[0059] It is preferable to control the wind speed during drying to between 1 m / s and 8 m / s. If the wind speed is 1 m / s or higher, the solvent dries more easily. If the wind speed is 8 m / s or lower, it is easier to suppress the phenomenon of the solvent being blown away by the wind. The drying speed is affected by the wet-bulb temperature, which includes the heat transfer coefficient of the boundary film between the coating and the air inside the drying oven, and the solvent vapor concentration in the atmosphere. The heat transfer coefficient of the boundary film is related to the wind speed hitting the coating, and drying is easier as the wind speed increases. On the other hand, as mentioned above, if the wind is too strong, the coating will be blown away by the wind during drying, which can easily cause uneven film thickness. Therefore, by adjusting the solvent contained in the resin composition and using a solvent with a low latent heat of vaporization as a secondary solvent in addition to the main solvent, the drying speed can be easily adjusted while reducing the influence of drying temperature and drying wind speed.

[0060] Furthermore, as another means of adjusting the C / M element molar ratio or relative C / M ratio of each surface, for example, a method of adjusting the angle of repose of the hollow inorganic particles as described above can be used. The angle of repose of the hollow inorganic particles is preferably 45° or more and 60° or less, and more preferably 48° or more and 58° or less.

[0061] Methods for adjusting the angle of repose of hollow inorganic particles include, for example, applying mechanical or electrical shock to the hollow inorganic particles. Specifically, these include jet mills, pin mills, blenders, twin-screw extruders, mixers, and plasma treatment. From the viewpoint of achieving both efficient adjustment of the angle of repose and suppression of rupture (shell breakage) of the hollow inorganic particles, plasma treatment is preferred as the method.

[0062] Appropriate plasma treatment of hollow inorganic particles alters the fine surface shape and functional groups, making it easier to set the angle of repose within an appropriate range. The equipment and conditions used for plasma irradiation can be those commonly used in various industrial plasma treatments. The mechanism of industrial equipment that generates plasma often involves ionizing a gas by applying an electric field between electrodes in a reduced pressure environment of about 0.1 to 150 Pa. Various forms of applying an electric field in such a reduced pressure environment are possible, but the basic method is DC discharge, where two electrodes, positive and negative, are placed in a rarefied gas atmosphere and a voltage is applied. The equipment is not particularly limited as long as it is capable of exposing powder to plasma generated by ionizing the atmospheric gas through a discharge phenomenon, but from the viewpoint of further promoting chemical reactions such as the imparting of modifying groups to the particle surface of the powder, equipment using glow discharge is preferred.

[0063] From the viewpoint of ensuring more even contact between the powder and the plasma generated by glow discharge, the following irradiation method is preferable. Specifically, it is preferable to rotate a rotary tabletop vacuum plasma apparatus, which has a rotary drum-type processing tank with a rotating axis that acts as a glow discharge electrode, generate plasma in its internal space, and irradiate the introduced powder evenly with the plasma while stirring it. The angle of repose can be easily adjusted by appropriately adjusting the rotation speed of the processing tank and the rotation axis of the processing tank. Furthermore, the method of irradiating hollow inorganic particles with plasma is not limited to these methods, and effects can also be obtained by placing the powder (hollow inorganic particles) thinly on a plane or stirring the placed powder at regular intervals. The vacuum level is preferably 1 Pa to 100 Pa, and the processing atmosphere may use an inert gas such as nitrogen or argon. However, from the viewpoint of uniform processing, it is preferable to use argon.

[0064] The plasma treatment temperature for hollow inorganic particles is preferably 10°C or lower, and more preferably 0°C or lower. Treatment at temperatures above 10°C tends to lower the angle of repose because etching progresses across the entire surface, removing irregularities on the silica surface. On the other hand, treatment at low temperatures below 10°C is preferable because it involves the addition of chemical functional groups rather than physical etching, increasing the interaction between inorganic particles and tending to raise the angle of repose.

[0065] The resin composition used in this manufacturing method contains the hollow inorganic particles described above, and may also contain the thermosetting resin described above, other inorganic materials, crosslinking agents, flame retardants, radical initiators, silane coupling agents, etc. The resin composition may also be a dispersion containing hollow inorganic particles and may contain a solvent (dispersion medium).

[0066] (Solvent) As the solvent used in the above resin composition, conventionally known solvents can be appropriately selected and used. One type of solvent may be used alone, or multiple types may be used in combination, for example, as a mixed solvent. Furthermore, by using a mixed solvent, the drying speed, i.e., the film shrinkage speed, can be easily controlled. Due to its compatibility with the resin composition, it is preferable to include a second solvent with toluene as the main solvent (first solvent). It is also possible to include a third solvent. From the viewpoint of adjusting the drying speed and ensuring suitable wettability to the substrate, the second solvent is preferably a ketone, ester, or acetate type.

[0067] The surface tension of the second solvent is preferably 20 mN / m to 40 mN / m, and more preferably 22 mN / m to 35 mN / m. Within this range, good solubility of the resin composition can be maintained while easily ensuring wettability to the substrate.

[0068] The amount of the second solvent mixed in may be, for example, 5 parts by mass or more and 49 parts by mass or 10 parts by mass or more and 40 parts by mass per 100 parts by mass of the first solvent.

[0069] When butyl acetate is used as the baseline (1.0), the relative evaporation rate of the second solvent is preferably between 0.5 and 5.0, and more preferably between 1.0 and 4.5. By setting the relative evaporation rate of the second solvent within this range, it is easier to adjust the drying rate to an appropriate range.

[0070] The relative evaporation rate of the mixed solvent, which is a mixture of the main solvent and the second solvent, is preferably 1.0 to 4.5, and more preferably 1.5 to 4.0.

[0071] The relative evaporation rate of a mixed solvent refers to the average of the relative evaporation rates of each solvent by weight ratio. Furthermore, the relative evaporation rate refers to the relative evaporation rate when the evaporation rate of n-butyl acetate is set to 1.0, as described in J. Ramsbotham: Prog. Org. Coatings, 8, 113 (1980).

[0072] The relative evaporation rates of the main solvents are shown below: Toluene: 2.0, Butyl acetate: 1.0, Isopropyl acetate: 3.5, Xylene: 0.76.

[0073] Resin compositions (resin varnishes) can be dispersed using conventionally known methods. More specifically, dispersion can be carried out using homodispersers, homogenizers, ultrasonic dispersers, ball mills, bead mills, etc. Among these, it is preferable to disperse the resin composition using a ball mill or bead mill from the viewpoint of preventing the hollow inorganic particles from breaking.

[0074] A ball mill is a method of crushing particles inside a container by placing a predetermined weight of resin varnish and balls called media into the container and rotating the container. The balls can be made of materials such as glass, zirconia, silicon nitride, or agate, but zirconia balls are preferred because of their pulverization properties and minimal wear on the balls themselves.

[0075] The ball diameter is preferably 1,000 to 10,000 times the primary particle size of the hollow inorganic particles in the resin varnish. For example, when dispersing hollow inorganic particles with an average particle size of 1 μm, balls of 1 mm to 10 mm in diameter are preferred. If the ball diameter is 1,000 times or more the diameter of the hollow inorganic particles, disintegration proceeds easily, and if it is 10,000 times or less, the hollow inorganic particles can be easily dispersed without breaking their shells. By sufficiently improving dispersibility, it is easier to adjust the C / M element molar ratio of each surface when the resin varnish is applied and made into a sheet.

[0076] Thermosetting resin sheets are obtained by continuously coating a resin varnish onto a substrate film and drying it, but experimentally, sheets can be produced in single-sheet form. Various existing coating methods include gravure coating, bar coating, die coating, comma coating, roll coating, and lip coating. Among these, die coating is particularly preferred from the viewpoint of uniform thickness and prevention of varnish drying.

[0077] The die-coating method involves using a quantitative pump to deliver resin varnish, which is then dispensed through the slits of the die and applied to the substrate. While quantitative pumps include gear pumps, mono pumps (a trademark of Hyoshin Equipment Co., Ltd.), and diaphragm pumps, mono pumps are preferred due to their low pulsation and reduced risk of crushing hollow inorganic particles. Furthermore, the stator of the mono pump is preferably made of rubber, as this allows for liquid delivery without crushing the hollow inorganic particles.

[0078] The manifold, which is the liquid reservoir inside the die, is preferably semicircular in shape, and its diameter is preferably between 10 mm and 40 mm. Within this range, hollow inorganic particles and solid inorganic particles are less likely to accumulate in the manifold, and a uniform C / Si element molar ratio can be easily maintained even with long rolls.

[0079] The die lip opening is preferably between 2 and 10 times the wet thickness during coating. Within this range, flow is generated due to shear inside the lip, making it easier for the C / M element molar ratio of the coating film after coating to fall within the desired range. If the lip opening exceeds 10 times, a distribution of hollow inorganic particles occurs inside the lip, and the C / M element molar ratio tends to increase. If the lip opening is 2 times or less, strong shear is applied, and hollow inorganic particles tend to accumulate in the center in the direction of coating film thickness.

[0080] <Printed Wiring Board> The printed wiring board according to this disclosure includes a thermosetting resin sheet according to this disclosure. The obtained thermosetting resin sheet is bonded to a substrate, such as a prepreg on which wiring is formed, a substrate impregnated with glass cloth, or glass, by lamination (for example, the second surface side of the thermosetting resin sheet). In the above lamination, if the thermosetting resin sheet has a protective film (for example, on the second surface side of the sheet), the protective film is removed, and if necessary, the thermosetting resin sheet and the circuit board are preheated, and the thermosetting resin sheet is pressed onto the circuit board while applying pressure and heating. In this sheet, a method of laminating to the circuit board under reduced pressure by vacuum lamination is preferably used. The lamination conditions are not particularly limited, but for example, the pressing temperature (lamination temperature) is preferably 70 to 140°C, and the pressing pressure is preferably 1 to 11 kgf / cm².２ (9.8×10 ４ ~107.9×10 ４ N / m ２ ), and it is preferable to laminate under a reduced pressure of 20 mmHg (26.7 hPa) or less of air pressure. Also, the lamination method may be a batch type or a continuous type using a roll. Vacuum lamination can be performed using a commercially available vacuum laminator. Examples of commercially available vacuum laminators include, for example, Vacuum Applicator manufactured by Nichigo-Morton Co., Ltd., Vacuum Pressure Type Laminator manufactured by Meiki Seisakusho Co., Ltd., Roll Type Dry Coater manufactured by Hitachi Industries Co., Ltd., Vacuum Laminator manufactured by Hitachi AIC Co., Ltd., etc. As described above, a printed wiring board is obtained.

[0081] <Semiconductor Device> Regarding the semiconductor device according to the present disclosure, as long as it includes the printed wiring board according to the present disclosure, conventionally known components can be appropriately used for other configurations. For example, a semiconductor device is manufactured by joining a semiconductor element to a connection electrode portion on a multilayer printed wiring board. The mounting method of the semiconductor element is not particularly limited, and examples include wire bonding mounting, flip chip mounting, mounting using an anisotropic conductive film (ACF), mounting using a non-conductive film (NCF), etc.

[0082] Hereinafter, the present disclosure will be described in more detail using a plurality of examples, but the present disclosure is not limited to these examples. Note that Examples 1 to 11 are examples according to the present disclosure, and Examples 12 to 15 are comparative examples.

[0083] <Production of Hollow Inorganic Particles> (Production Example 1) Hollow silica particles 1 were produced by the method described in Production Example 1 of JP-A-2013-173841. The average particle diameter of the hollow silica particles 1 was 1 μm, and the angle of repose was 42°.

[0084] (Manufacturing Example 2) The hollow silica particles 1 obtained in Manufacturing Example 1 were subjected to plasma treatment using a rotary tabletop vacuum plasma apparatus YHS-DφS (product name, manufactured by Kai Semiconductor), which is equipped with a rotary drum-type processing tank with a rotating axis that serves as a glow discharge electrode. Cooling tubes were wrapped around the outside of the drum, and a refrigerant at -10°C was circulated using a chiller circulation device. The internal temperature was 0°C. The pressure inside the processing tank was set to 5 Pa, the atmosphere to Ar, and plasma was generated in the internal space while the tank was rotating. The rotation speed was 10 rpm, and the rotation axis of the processing tank was tilted 20 degrees from the horizontal. Plasma treatment was performed for 5 minutes to obtain hollow silica particles 2. The average particle size of the hollow silica particles 2 was 1 μm, and the angle of repose was 45°.

[0085] (Manufacturing Example 3) Hollow silica particles 3 were prepared in the same manner as in Manufacturing Example 2, except that the plasma treatment time was changed to 10 minutes. The average particle size of the hollow silica particles 3 was 1 μm, and the angle of repose was 58°.

[0086] (Manufacturing Example 4) Hollow silica particle preformation 4 was prepared in the same manner as in Manufacturing Example 1, except that the stirring during the production of emulsion droplets was increased to change the emulsion diameter to 0.5 μm. Then, the obtained hollow silica particle preformation 4 was subjected to plasma treatment under the same conditions as in Manufacturing Example 3 to produce hollow silica particles 4. The average particle size of the hollow silica particles 4 was 0.5 μm, and the angle of repose was 58°.

[0087] (Manufacturing Example 5) Hollow silica particles 5 were prepared in the same manner as in Manufacturing Example 2, except that the plasma treatment time was changed to 20 minutes. The average particle size of the hollow silica particles 5 was 1 μm, and the angle of repose was 62°.

[0088] (Manufacturing Example 6) Hollow silica particle preformation 6 was prepared in the same manner as in Manufacturing Example 1, except that the stirring during the production of emulsion droplets was weakened to change the emulsion diameter to 3.0 μm. Then, the obtained hollow silica particle preformation 6 was subjected to plasma treatment under the same conditions as in Manufacturing Example 3 to produce hollow silica particles 6. The average particle size of the hollow silica particles 6 was 3 μm, and the angle of repose was 58°.

[0089] (Example 1) The following materials were added to 60 parts by mass of toluene and 20 parts by mass of butyl acetate, which are solvents, and the mixture was stirred until it became a clear liquid. - Thermosetting resin (manufactured by SABIC, product name: Noryl SA9000) 14 parts by mass, - SEBS elastomer (hydrogenated styrene thermoplastic elastomer) (manufactured by Kraton, product name: MD1623) 7 parts by mass, - Crosslinking agent 1 (manufactured by Hantzman, product name: ARALDITE MT35610) 10 parts by mass, - Crosslinking agent 2 (manufactured by Regina Electronics, BVPE (bis(4-vinylphenyl)ethane)) 3.5 parts by mass, - Phosphorus-based flame retardant (manufactured by Otsuka Chemical Co., Ltd., product name: SPV-100) 20 parts by mass, - Radical initiator (manufactured by United Initiator, product name: CUROX CC-DC) 1 part by mass 0.5 parts by mass of silane coupling agent (manufactured by Toray Dow, trade name: OFS-6030). The viscosity of the mixture at this stage was 0.05 Pa·s. Subsequently, 17 parts by mass of hollow silica particles 2 and 27 parts by mass of solid silica particles (manufactured by Sibelco, trade name: SS-15V, average particle size 2 μm) were added to the mixture, and the mixture was further stirred with a high-speed rotary mixer to produce a resin composition (resin varnish). The relative evaporation rate of the mixed solvent was 1.8, and the solid content in the resin composition was 55% by mass.

[0090] The solid content in the resin composition (resin varnish) was measured as follows. Specifically, 5 g of varnish was weighed onto an aluminum pan using a precision balance and placed in a 150°C hot air drying oven for 3 hours to dry completely. The solid content was then calculated based on the following formula. The same calculation method was used for subsequent measurements. Solid content (mass%) = {Mass after drying (g) - Mass before drying (g)} / (Mass before drying (g))

[0091] The obtained resin composition was delivered by a mono pump and coated using a die coater in a roll-to-roll manner. The die lip opening was 250 μm, the substrate was 38 μm thick PET (Lintec Corporation, product name: 6501), the coating width was 500 mm, and the wet film thickness was 100 μm. Hot air at 100°C was applied to the film surface from a two-dimensional nozzle at a wind speed of 4 m / s, and the film thickness was dried while controlling the shrinkage rate to 1 μm / s. At that time, the LogPe calculated by the method described above was 4.0. Furthermore, an embossed biaxially oriented polypropylene film was laminated at a temperature of 70°C and a linear pressure of 100 N / cm. The thickness of the obtained thermosetting resin sheet 1 was 40 μm.

[0092] (Example 2) A thermosetting sheet 2 was prepared in the same manner as in Example 1, except that hollow silica particles 3 were used instead of hollow silica particles 2 as hollow inorganic particles. The thickness of the obtained thermosetting resin sheet 2 was 40 μm.

[0093] (Example 3) A resin composition was prepared in the same manner as in Example 1, except that 40 parts by mass of toluene and 40 parts by mass of xylene were used as solvents, and hollow silica particles 4 were used instead of hollow silica particles 2. The relative evaporation rate of the mixed solvent was 1.4, and the solid content in the resin composition was 55% by mass. A thermosetting resin sheet 3 was prepared in the same manner as in Example 1, except that the shrinkage rate of the film thickness was controlled to 0.2 μm / s and the resulting LogPe was 3.0. The thickness of the obtained thermosetting resin sheet 3 was 40 μm.

[0094] (Example 4) A resin composition was prepared in the same manner as in Example 1, except that 60 parts by mass of toluene and 20 parts by mass of isopropyl acetate were used as solvents. The average relative evaporation rate of the mixed solvent was 2.4, and the solid content in the resin composition was 55% by mass. A thermosetting resin sheet 4 was then prepared in the same manner as in Example 1, except that the wet film thickness was 100 μm, hot air at 100°C was applied to the film surface from a two-dimensional nozzle at a wind speed of 6 m / s, the shrinkage rate of the film thickness was controlled to 10 μm / s, and the LogPe at that time was set to 5.0. The thickness of the obtained thermosetting resin sheet 4 was 40 μm.

[0095] (Example 5) A resin composition (resin varnish) was prepared by adding the following materials to 60 parts by mass of toluene and 20 parts by mass of butyl acetate, which are solvents, and further stirring with a high-speed rotary mixer. The solid content of the resin composition was 55% by mass. - Biphenyl aralkyl epoxy resin (manufactured by Nippon Kayaku Co., Ltd., product name "NC-3000H") 5 parts by mass, naphthalene epoxy resin (manufactured by DIC Corporation, product name "HP4032SS") 5 parts by mass, bisphenol A type epoxy resin and bisphenol F type epoxy mixture (manufactured by Nippon Steel Chemical & Material Co., Ltd., product name "ZX1059") 31 parts by mass, - Curing agent: Active ester-based curing agent (manufactured by DIC Corporation, product name "HPC-8150-62T") 5 parts by mass, phenol-based curing agent having a triazine skeleton and novolac structure (manufactured by DIC Corporation, product name "LA-3018-50P") 5 parts by mass, - Phenoxy resin (manufactured by Mitsubishi Chemical Corporation, product name "YX7553BH30") 5 parts by mass, - Hollow silica particles 2 17 parts by mass, - Solid silica particles (manufactured by Sibelco, trade name: SS-15V, average particle size 2 μm) 27 parts by mass.

[0096] The obtained resin composition was delivered by a mono pump and coated using a die coater in a roll-to-roll manner. The die lip opening was 250 μm, the substrate was 38 μm thick PET (Lintec Corporation, product name "6501"), the coating width was 500 mm, and the wet film thickness was 100 μm. Hot air at 100°C was applied to the film surface from a two-dimensional nozzle at a wind speed of 4 m / s, and the film thickness was dried while controlling the shrinkage rate to 1 μm / s. The LogPe at that time was 4.0. Furthermore, an embossed biaxially oriented polypropylene film was laminated at a temperature of 70°C and a linear pressure of 100 N / cm. The thickness of the obtained thermosetting resin sheet 5 was 40 μm.

[0097] (Example 6) A thermosetting resin sheet 6 was prepared in the same manner as in Example 1, except that the amount of hollow silica particles 2 was changed to 12 parts by mass and the amount of solid silica particles to 32 parts by mass. The thickness of the thermosetting resin sheet 6 was 40 μm.

[0098] (Example 7) A thermosetting resin sheet 7 was prepared in the same manner as in Example 1, except that the amount of hollow silica particles 2 was changed to 27 parts by mass and the amount of solid silica particles to 17 parts by mass. The thickness of the thermosetting resin sheet 7 was 40 μm.

[0099] (Example 8) The following materials were added to 60 parts by mass of toluene and 20 parts by mass of butyl acetate, which are solvents, and the mixture was stirred until it became a clear liquid. - Thermosetting resin (manufactured by SABIC, product name: Noryl SA9000) 9 parts by mass, - SEBS elastomer (manufactured by Kraton, product name: MD1623) 4.5 parts by mass, - Crosslinking aid (manufactured by Hantzman, product name: ARALDITE MT35610) 6.4 parts by mass, - Crosslinking aid 2 (manufactured by Regina Electronics, BVPE (bis(4-vinylphenyl)ethane)) 2.2 parts by mass, - Phosphorus-based flame retardant (manufactured by Otsuka Chemical Co., Ltd., product name: SPV-100) 12.8 parts by mass, - Radical initiator (manufactured by United Initiator, product name: CUROX CC-DC) 0.6 parts by mass - Silane coupling agent (manufactured by Toray Dow, product name: OFS-6030) 0.3 parts by mass.

[0100] At this stage, the viscosity of the mixture was 0.02 Pa·s. Subsequently, 27 parts by mass of hollow silica particles 2 and 37 parts by mass of solid silica particles were added to the mixture, and the mixture was further stirred with a high-speed rotary mixer to prepare a resin composition (resin varnish). The relative evaporation rate of the mixed solvent was 1.8, and the solid content in the resin composition was 55% by mass. Next, the obtained resin composition was delivered by a mono pump and coated using a die coater in a roll-to-roll manner. The die lip opening was 250 μm, the substrate was 38 μm thick PET "6501" manufactured by Lintec Corporation, the coating width was 500 mm, and the coating was applied to achieve a wet film thickness of 100 μm. Hot air at 100°C was applied to the film surface from a two-dimensional nozzle at a wind speed of 4 m / s, and the film thickness was dried while controlling the shrinkage rate to 1 μm / s. The LogPe at that time was 3.6. Furthermore, an embossed biaxially oriented polypropylene film was laminated at a temperature of 70°C and a linear pressure of 100 N / cm. The resulting thermosetting resin sheet 8 had a thickness of 40 μm.

[0101] (Example 9) A thermosetting resin sheet 9 was prepared in the same manner as in Example 1, except that hollow silica particles 6 were used instead of hollow silica particles 2. The thickness of the thermosetting resin sheet 9 was 40 μm.

[0102] (Example 10) A thermosetting resin sheet 10 was prepared in the same manner as in Example 1, except that the wet film thickness was set to 25 μm. The thickness of the thermosetting resin sheet 10 was 10 μm.

[0103] (Example 11) A thermosetting resin sheet 11 was prepared in the same manner as in Example 1, except that the wet film thickness was set to 375 μm. The thickness of the thermosetting resin sheet 11 was 150 μm.

[0104] (Example 12) A thermosetting resin sheet 12 was prepared in the same manner as in Example 1, except that hollow silica particle 1 was used instead of hollow silica particle 2. The thickness of the thermosetting resin sheet 12 was 40 μm.

[0105] (Example 13) A thermosetting resin sheet 13 was prepared in the same manner as in Example 1, except that hollow silica particles 5 were used instead of hollow silica particles 2. The thickness of the thermosetting resin sheet 13 was 40 μm.

[0106] (Example 14) A clear mixed solution was prepared in the same manner as in Example 1, except that the solvent was changed to 20 parts by mass of toluene and 35 parts by mass of isopropyl acetate. The viscosity of the mixed solution at this stage was 0.2 Pa·s. The relative evaporation rate of the mixed solvent was 2.9, and the solid content in the resin composition prepared in the same manner as in Example 1 was 65% by mass. Furthermore, a thermosetting resin sheet 14 was prepared in the same manner as in Example 1, except that it was coated to a wet film thickness of 80 μm, hot air at 100°C was applied to the film surface from a two-dimensional nozzle at a wind speed of 6 m / s, the shrinkage rate of the film thickness was controlled to 5 μm / s, and the LogPe at that time was set to 5.2. The thickness of the obtained thermosetting resin sheet 14 was 40 μm.

[0107] (Example 15) A clear mixed solution was prepared in the same manner as in Example 1, except that the solvent was changed to 40 parts by mass of toluene and 100 parts by mass of xylene. The viscosity of the mixed solution at this stage was 0.005 Pa·s. The relative evaporation rate of the mixed solvent was 1.0, and the solid content in the resin composition prepared in the same manner as in Example 1 was 40% by mass. Furthermore, a thermosetting resin sheet 15 was prepared in the same manner as in Example 1, except that the sheet was coated to a wet film thickness of 120 μm, hot air at 100°C was applied to the film surface from a two-dimensional nozzle at a wind speed of 2.5 m / s, the shrinkage rate of the film thickness was controlled to 0.5 μm / s, and the LogPe at that time was set to 2.7. The thickness of the obtained thermosetting resin sheet 15 was 40 μm.

[0108] The analytical and evaluation methods for the thermosetting resin sheets obtained in each example are shown below.

[0109] <Determination of C / Si elemental molar ratio for each surface> Osmium (Os) was deposited onto one side (both the first and second surfaces) of each thermosetting resin sheet (with the protective film and substrate removed) obtained from each example. EDS measurements were performed using a SEM-EDS (SEM: Hitachi High-Tech Corporation, product name: SU7000; EDS: EDAX Corporation, product name: Pegasus) at an acceleration voltage of 15 kV and in backscattered electron imaging mode. The field of view for EDS measurements was 1.2 mm square. For each surface, the C / Si elemental molar ratio was determined from the obtained molar amounts of C and Si. From these values, the ratio of the C / Si elemental molar ratio of the first surface to the C / Si elemental molar ratio of the second surface (relative C / Si ratio) was determined.

[0110] <Wiring Embedding Ability> On a 2-inch silicon wafer, 100 circuits with a wiring width of 50 μm, a wiring depth of 20 μm, and a groove width of 50 μm between wirings were formed in parallel by dry etching. Subsequently, the thermosetting resin sheets obtained from each example were placed on the silicon wafer and laminated using a vacuum laminator (manufactured by Japan Steel Works, product name: MVLP300). During this process, the hot plate temperature was reduced for 30 seconds at 130°C, then increased to 1 MPa over 30 seconds, and held at 1 MPa for 30 seconds. After that, the cross-section of the removed laminate was observed. A: The resin was embedded in the width of the grooves, and no gaps were observed at the silicon-sheet interface. B: The resin was embedded in the width of the grooves, but gaps were observed at the silicon-sheet interface. C: The resin was not embedded in the width of the grooves.

[0111] <Interlayer Insulation> (1) Preparation of Adhesive Film A PET film with a release layer (Lintec Corporation, product name "AL5") was prepared as a protective film. On this release layer, the resin composition (resin varnish) obtained in each example was uniformly applied using a die coater so that the thickness of the resin composition layer after drying was 12 μm. Then, the adhesive film was obtained by drying at 80 to 110°C (average 95°C) for 6 minutes.

[0112] (2) Substrate preparation A glass cloth substrate epoxy resin double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.8 mm, manufactured by Resonaq Corporation, product name: MCL-E-705G) was prepared by etching a circuit pattern onto both sides, and then a roughening treatment was performed with a micro-etching agent (manufactured by MEC Corporation, product name "CZ8100") to produce a substrate (circuit board).

[0113] (3) Lamination of adhesive film The adhesive film prepared in (1) above was laminated on both sides of the circuit board using a batch-type vacuum pressure laminator (manufactured by Japan Steel Works Ltd., product name "MVLP-300") so that the resin composition layer was bonded to the circuit board. Lamination was carried out by reducing the pressure to 13 hPa or less by depressurizing for 30 seconds, then pressurizing to 1.0 MPa at 130°C for 30 seconds, and then pressing for another 30 seconds.

[0114] (4) After lamination of the curing adhesive film on the resin composition layer, the protective film was peeled off to expose the resin composition layer. Next, the resin composition layer was heat-cured at 185°C for 30 minutes to form a thermosetting resin sheet.

[0115] (5) Roughening treatment The thermosetting resin sheet obtained in (4) above is treated with a swelling solution (Atotec Japan Co., Ltd., product name "Swelling Dip Securigant P", an aqueous sodium hydroxide solution containing diethylene glycol monobutyl ether) at 60°C for 10 minutes, and then with a roughening solution (Atotec Japan Co., Ltd., product name "Concentrate Compact P", KMnO ４ The substrate was immersed in an aqueous solution of 60 g / L of sodium sulfate and 40 g / L of NaOH at 80°C for 20 minutes, and finally in a neutralizing solution (Atotec Japan Co., Ltd., product name "Reduction Solution Securigant P", sulfuric acid aqueous solution) at 40°C for 5 minutes. After that, it was dried at 80°C for 30 minutes. The resulting substrate is referred to as "Evaluation Substrate 1".

[0116] (6) A conductive layer was formed on the evaluation substrate 1 by a semi-additive plating method. Specifically, the evaluation substrate 1 was plated with PdCl ２ The substrate was immersed in an electroless plating solution containing [a specific substance] at 40°C for 5 minutes, and then immersed in an electroless copper plating solution at 25°C for 20 minutes. After annealing by heating at 150°C for 30 minutes, an etching resist was formed, and after pattern formation by etching, copper sulfate electroplating was performed to form a conductive layer with a thickness of 30 μm. Next, annealing was performed at 190°C for 60 minutes. The obtained substrate is referred to as "evaluation substrate 2".

[0117] (7) Preparation of test pieces for insulation testing Evaluation board 2 was cut to a size of 10 cm x 10 cm, and 10 pieces of tape with a diameter of 1 cm were attached to one side. The plating on the parts without tape was etched with an etching solution mainly composed of iron(III) chloride at 40°C. After washing with tap water, the tape was removed and washed with pure water filtered using Millipore filtration. Then, it was dried in a 100°C oven for 15 minutes, and then cured in a 190°C oven for 60 minutes. The resin at the edge of the board was scraped off to expose the underlying copper foil, and copper wires were soldered as electrodes to the center of the 10 plated copper foils and the underlying copper foil. Next, it was washed with dichloromethane and methanol in order, and dried in a 130°C oven for 30 minutes to obtain a test piece.

[0118] (8) Measurement of Resistance The insulation resistance of the test piece obtained in (7) above was measured using a resistance measuring instrument (manufactured by J-RAS, product name "ECM-100"). Then, the test piece was subjected to an environment of 130°C and 85% relative humidity using a HAST tester (manufactured by Kusumoto Kasei Co., Ltd., product name "PM422"), and a voltage of 3.3V was applied across both ends of the electrodes. After 200 hours, the test piece was removed and its insulation resistance was measured. The insulation resistance of the test piece after 200 hours was measured and evaluated based on the following criteria: A: Less than 3 wirings with an impedance of less than 1 × 10^7 Ω B: 3 or more wirings with an impedance of less than 1 × 10^7 Ω but less than 5 C: 5 or more wirings with an impedance of less than 1 × 10^7 Ω

[0119] <Measurement of Dielectric Constant (Dk) and Dielectric Loss Tangent (Df)> For the thermosetting resin sheets obtained in each example, the dielectric constant (Dk) and dielectric loss tangent (Df) at a frequency of 10 GHz were measured at room temperature (25°C) using a vector network analyzer (Agilent Technologies "E8361C" (product name)) by the SPDR method. The results for each example are shown below.

[0120]

[0121]

[0122] From the above, it can be seen that this sheet, which contains hollow inorganic particles and satisfies a specific thickness and a specific relative C / Si ratio, can ensure insulation while maintaining good wiring embedding properties, low dielectric constant, and low dielectric loss tangent. Furthermore, by using this sheet, printed circuit boards and semiconductor devices with excellent electrical properties can be provided.

[0123] This disclosure is not limited to the embodiments described above, and may be modified as appropriate without departing from its spirit. Furthermore, this disclosure may be implemented by combining the embodiments described above or examples thereof as appropriate.

[0124] This application claims priority based on Japanese Patent Application No. 2024-160784, filed on 18 September 2024, and incorporates all of its disclosures herein.

Claims

1. A thermosetting resin sheet having a first surface positioned on the substrate side and a second surface facing the first surface, containing hollow inorganic particles, where M is the amount of metallic and metalloid elements, the ratio of the molar ratio of the C / M elements on the first surface to the molar ratio of the C / M elements on the second surface is 1.02 to 1.09, and the thickness is 10 to 150 μm.

2. The thermosetting resin sheet according to claim 1, wherein the molar ratio of C / M elements on the second surface is 3.2 to 6.

8.

3. The thermosetting resin sheet according to claim 1 or 2, wherein the molar ratio of C / M elements on the first surface is 3.3 to 7.

2.

4. The thermosetting resin sheet according to claim 1 or 2, wherein the dielectric constant at a frequency of 10 GHz is less than 2.

6.

5. The thermosetting resin sheet according to claim 1 or 2, wherein the dielectric loss tangent at a frequency of 10 GHz is 0.004 or less.

6. The thermosetting resin sheet according to claim 1 or 2, wherein the hollow inorganic particles contain an inorganic oxide containing one or more selected from aluminum, magnesium, silicon, titanium, and zinc.

7. The thermosetting resin sheet according to claim 1 or 2, wherein the hollow inorganic particles contain silica.

8. The thermosetting resin sheet according to claim 1 or 2, wherein the content of the hollow inorganic particles is 12 to 27% by mass.

9. The thermosetting resin sheet according to claim 1 or 2, wherein the average particle size of the hollow inorganic particles is 0.4 μm or more and 3.0 μm or less.

10. The thermosetting resin sheet according to claim 1 or 2, wherein the angle of repose of the hollow inorganic particles is 45° or more and 60° or less.

11. The thermosetting resin sheet according to claim 1 or 2, further comprising solid inorganic particles.

12. The thermosetting resin sheet according to claim 11, wherein the content of the solid inorganic particles is 17 to 37% by mass.

13. A method for producing a thermosetting resin sheet, comprising coating a resin composition containing hollow inorganic particles onto a substrate, drying it so that the common logarithm LogPe of the Peclet number Pe calculated by the following formula 1 is 3.0 to 5.0, and producing a thermosetting resin sheet with a thickness of 10 to 150 μm, wherein the ratio of the molar ratio of the C / M elements of the first surface to the molar ratio of the second surface facing the first surface on the substrate side is 1.02 to 1.09, when M is the amount of metallic and metalloid elements. (Formula 1) Pe = (6πμEHR) / (kT) μ: Initial viscosity of the resin composition without particles (Pa·s) E: Film shrinkage rate (m / s) H: Wet film thickness (m) R: Average particle size of hollow inorganic particles (m) k: Boltzmann constant (J / K) T: Liquid temperature (K) 14. The method for producing a thermosetting resin sheet according to claim 13, wherein the drying temperature during the drying process is 60°C or higher and 150°C or lower.

15. The method for manufacturing a thermosetting resin sheet according to claim 13 or 14, wherein the wind speed during drying is 1 m / s or more and 8 m / s or less.

16. The method for producing a thermosetting resin sheet according to claim 13 or 14, wherein the resin composition contains a solvent, and the solvent is a mixed solvent containing toluene and a second solvent other than toluene.

17. The method for producing a thermosetting resin sheet according to claim 16, wherein the relative evaporation rate of the mixed solvent is 1.0 or more and 4.5 or less.

18. A printed circuit board comprising the thermosetting resin sheet according to claim 1 or 2.

19. A semiconductor device comprising a printed circuit board as described in claim 18.

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