Resin substrates with dielectric properties that have low frequency dependence

Abstract

This invention provides a resin substrate with a low dielectric tangent in the high-frequency region and dielectric properties with low frequency dependence. The resin substrate comprises an organic resin and a quartz glass cloth. The resin substrate is characterized in that: the dielectric tangent of the aforementioned organic resin at 10 GHz is 0.0002 to 0.0020, and the 40 GHz / 10 GHz ratio is 0.4 to 0.9; the dielectric tangent of the aforementioned quartz glass cloth at 10 GHz is 0.0001 to 0.0015, and the 40 GHz / 10 GHz ratio is 1.2 to 2.0; the dielectric tangent of the aforementioned resin substrate at 10 GHz is 0.0001 to 0.0020, and the 40 GHz / 10 GHz ratio is 0.8 to 1.2.

Description

Technical Field

[0001] This invention relates to a resin substrate with dielectric properties that have low frequency dependence. Prior Technology

[0002] Currently, with the advent of high-speed communication technologies such as 5G (5th Generation), there is a strong demand for high-speed communication substrates or antenna substrates that minimize transmission loss even when using high frequencies such as millimeter waves. Furthermore, in information terminals such as smartphones, there is a significant push towards high-density packaging and ultra-thin designs for wiring boards.

[0003] For high-speed substrates exceeding 10GHz, it is difficult to ensure signal quality using previous technologies.

[0004] To meet the demands of high-speed communications such as 5G, laminated boards are widely used, which are made by laminating prepregs and then heating and pressing them for curing. These prepregs are obtained by impregnating low-dielectric glass cloths such as D-glass, NE-glass, and L-glass with thermoplastic resins such as fluoropolymers or polyphenylene ethers, and then further impregnating them with low-dielectric epoxy resins or low-dielectric maleimide resins. However, although D-glass, NE-glass, and L-glass are glass cloths with improved dielectric properties, the dielectric tangent for any of these glasses is still very high, around 0.002 to 0.005 in the high-frequency region above 10 GHz, and the frequency dependence is also significant. Therefore, they are difficult to use as high-speed substrates for millimeter-wave applications and are not suitable for a wide range of uses.

[0005] Furthermore, the signal transmission loss is as shown in Edward A. Wolff's equation: Transmission loss ∝ √ε × tanδ. It is known that the smaller the dielectric constant (ε) and dielectric tangent (tanδ) of the material, the more the above transmission loss is improved.

[0006] Regarding the reduction of dielectric tangent in organic resin substrates such as printed circuit boards, the common method is to use inorganic powders or glass cloth with a dielectric tangent lower than that of the resin. However, when viewed from a microscopic perspective, the dielectric properties of the resin acting as a binder differ from those of the inorganic powder or glass cloth, making it impossible to obtain a low-dielectric substrate with uniform dielectric properties even at high frequencies such as millimeter waves. In particular, the following substrates are almost unknown: those with a dielectric tangent below 0.0015 in a wide high-frequency region such as 1 GHz to 50 GHz, and uniform dielectric properties with a dielectric constant of 4.0 or less.

[0007] Silica powder or quartz glass cloth, as representative inorganic materials with low dielectric properties, are characterized by their small coefficient of thermal expansion, excellent insulation and dielectric properties, and their ability to be used as inorganic powders added to resins or as reinforcing materials for substrates. Generally, quartz glass cloth or silica powder is known to have excellent dielectric properties, but currently, the dielectric tangent of quartz glass cloth or silica powder cannot be arbitrarily adjusted.

[0008] Generally speaking, the amount of residual hydroxyl (OH) groups in quartz glass or silicon dioxide powder varies depending on the manufacturing method or heat treatment, and it is known that the difference in OH concentration leads to various differences in physical properties (Non-Patent Literature 1).

[0009] In Patent Document 1, although heat treatment is used to manufacture low-silanol silica powder, only the reduction rate of silanol groups (Si-OH) is mentioned. The amount of silanol in the treated silica powder is not measured, and the correlation with dielectric tangent is not mentioned.

[0010] Although Patent Document 2 discloses the relationship between the moisture content and dielectric tangent in silica glass fiber, it does not record any relationship with the amount of silanol. The dielectric tangent is also a measurement value obtained using glass fiber and PTFE (Polytetrafluoroethylene) printed substrate, so it does not show the correlation between the amount of silanol and the dielectric tangent of glass fiber.

[0011] The following situation is not known: reducing OH groups to a predetermined amount through high-temperature treatment to improve dielectric tangent. Furthermore, if quartz glass or silicon dioxide powder is heated at high temperatures, the strain increases, especially the strain on the glass surface (Non-Patent Document 2), thus significantly reducing strength. Therefore, it has not been put into practical use. [Previous Technical Documents] (Patent Documents)

[0012] Patent Document 1: Japanese Patent Application Publication No. 2-289416 Patent Document 2: Japanese Patent Application Publication No. 5-170483 (Non-patent literature)

[0013] Non-Patent Literature 1: Changes in OH Group Concentration in Silica Glass Accompanied by Heat Treatment, February 2011, Doctoral Pre-Doctoral Thesis, Graduate School of Engineering, Fukui University Non-Patent Literature 2: Structural Changes of Silica Glass Blocks Caused by Heat Treatment, February 2005, Doctoral Pre-Doctoral Thesis, Graduate School of Engineering, Fukui University Summary of the Invention

[0014] [The problem the invention aims to solve]

[0015] The prior art has the following problem: it is impossible to provide a substrate that has a low dielectric tangent and uniform dielectric properties in a wide high-frequency region of 1 GHz to 50 GHz.

[0016] The present invention was made to solve the above-mentioned problems, and its purpose is to provide a resin substrate that has a low dielectric tangent in the high-frequency region and dielectric properties with low frequency dependence. [Technical means to solve the problem]

[0017] To address the above problems, the present invention provides a resin substrate comprising an organic resin and a quartz glass cloth, characterized in that: The aforementioned organic resin exhibited a dielectric tangent of 0.0002 to 0.0020 at 10 GHz, and the ratio of its dielectric tangent at 40 GHz to that at 10 GHz (40 GHz / 10 GHz ratio) was 0.4 to 0.9. The dielectric tangent of the aforementioned quartz glass cloth measured at 10 GHz was 0.0001 to 0.0015, and the ratio of the dielectric tangent at 40 GHz to that at 10 GHz (40 GHz / 10 GHz ratio) was 1.2 to 2.0. The aforementioned resin substrate has a dielectric tangent of 0.0001 to 0.0020 at 10 GHz, and the ratio of the dielectric tangent at 40 GHz to the dielectric tangent at 10 GHz (40 GHz / 10 GHz ratio) is 0.8 to 1.2.

[0018] If the resin substrate of this invention is used, it has a low dielectric tangent in the high-frequency region and can exhibit dielectric properties with low frequency dependence.

[0019] In this case, it is preferable to further include silicon dioxide powder with a dielectric tangent of 0.0001 to 0.0015 at 10 GHz.

[0020] By incorporating this silicon dioxide powder, the coefficient of thermal expansion and dielectric properties of the substrate can be adjusted.

[0021] In addition, in this invention, the aforementioned organic resin may be one or more thermosetting resins selected from the group consisting of epoxy resin, allylated epoxy resin, maleimide resin, bismaleimide resin, cyanate ester resin, and cyclopentadiene-styrene copolymer resin.

[0022] This thermosetting resin is suitable for use in terms of the dielectric properties or strength of the resin substrate.

[0023] In this case, the aforementioned thermosetting resin is preferably a bismaleimide resin represented by the following general formula. In the aforementioned formula, A independently represents a tetravalent organic group containing an aromatic ring or an aliphatic ring, B is a divalent alkyl chain with an aliphatic ring containing heteroatoms and having 6 to 18 carbon atoms, Q independently represents a straight-chain alkyl chain with 6 or more carbon atoms, R independently represents a straight-chain or branched alkyl chain with 6 or more carbon atoms, n represents a number from 1 to 10, and m represents a number from 0 to 10.

[0024] This type of bismaleimide resin is suitable for low dielectricization of substrates.

[0025] In addition, in this invention, the aforementioned organic resin may be one or more thermoplastic resins selected from the group consisting of polyphenylene ether, polyether ether ketone, polyether ketone, polyether ether, and fluororesin.

[0026] This type of thermoplastic resin is also suitable for use in terms of the dielectric properties of the resin substrate.

[0027] In this case, the aforementioned thermoplastic resin is preferably a fluoropolymer.

[0028] This type of resin is better from the viewpoint of low dielectric properties.

[0029] Furthermore, the aforementioned fluororesin is preferably selected from one or more of the group consisting of polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA).

[0030] This type of fluororesin has a low dielectric tangent, making it quite ideal. [effect]

[0031] As described above, if the resin substrate of this invention is used, it also exhibits a low dielectric tangent in the high-frequency region, thus displaying dielectric characteristics with low frequency dependence. In particular, it can transmit signals with stable dielectric characteristics and good quality over a wide frequency band from 1 GHz to 50 GHz, thereby providing excellent high-frequency signal transmission characteristics.

[0032] Furthermore, by using the resin substrate of the present invention, an ideal substrate with very low transmission loss in high-speed communication such as millimeter waves can be fabricated. Simple Explanation of the Diagram

[0033] none Implementation

[0034] As mentioned above, it is required to develop a resin substrate that has a low dielectric tangent in the high-frequency region and dielectric properties with low frequency dependence.

[0035] In order to solve the above problems, the inventors have repeatedly devoted themselves to research, especially the low dielectric properties that have no frequency dependence. As a result, they found that by combining an organic resin with a negative correlation between the frequency dependence of dielectric tangent and frequency dependence with a quartz glass cloth or silicon dioxide powder with a positive correlation, it is possible to manufacture a resin substrate with very low frequency dependence and low dielectric properties.

[0036] In order to adapt the dielectric tangent of organic resins that are negatively correlated with the frequency dependence of dielectric tangent, the frequency dependence of dielectric tangent of quartz glass cloth, etc., can be easily adjusted to the target value by controlling the amount of hydroxyl (silanol) groups contained in quartz glass cloth or silica powder.

[0037] To obtain a dielectric tangent that is positively correlated with frequency, the amount of hydroxyl groups in the silica powder or quartz glass cloth can be easily controlled by heating it to a temperature of 500°C to 1500°C, thereby adjusting the dielectric tangent to any level. Furthermore, it has been found that by slightly etching the surface of the silica powder or quartz glass cloth, these surfaces become stronger, and the adhesion to the resin is improved; consequently, the tensile strength of the quartz glass cloth is significantly increased.

[0038] Furthermore, it was discovered that since the dielectric tangent of the quartz glass cloth and silicon dioxide powder can be arbitrarily varied, by adapting it to the frequency dependence of the dielectric tangent of the low-dielectric resin contained in the resin substrate, a resin substrate with minimal non-uniformity of dielectric tangent characteristics relative to frequency is made, which is suitable for low-dielectric substrates for high-speed communication in millimeter waves, etc., thus completing the present invention.

[0039] That is, the present invention relates to a resin substrate comprising organic resin and quartz glass cloth, characterized in that... The aforementioned organic resin exhibited a dielectric tangent of 0.0002 to 0.0020 at 10 GHz, and the ratio of its dielectric tangent at 40 GHz to that at 10 GHz (40 GHz / 10 GHz ratio) was 0.4 to 0.9. The dielectric tangent of the aforementioned quartz glass cloth measured at 10 GHz was 0.0001–0.0015, and the ratio of the dielectric tangent at 40 GHz to that at 10 GHz (40 GHz / 10 GHz ratio) was 1.2–2.0. The aforementioned resin substrate has a dielectric tangent of 0.0001 to 0.0020 at 10 GHz, and the ratio of the dielectric tangent at 40 GHz to the dielectric tangent at 10 GHz (40 GHz / 10 GHz ratio) is 0.8 to 1.2.

[0040] Thus, by adjusting and combining an organic resin having a dielectric tangent that is negatively correlated with frequency and a quartz glass cloth or silicon dioxide powder having a dielectric tangent that is positively correlated with frequency, which will become the matrix of the resin substrate, the inventors are able to manufacture a resin substrate that has stable dielectric properties in a wide frequency band of 1 GHz to 50 GHz, and is particularly suitable as a high-speed communication resin substrate for millimeter waves.

[0041] The present invention will now be described in detail, but it is not limited thereto.

[0042] This invention relates to a resin substrate (low dielectric substrate) comprising quartz glass cloth, and, if necessary, silicon dioxide powder and an organic resin with low dielectric properties (low dielectric resin), and having very low frequency dependence of dielectric tangent in the millimeter-wave region, making it suitable for high-speed communication low dielectric substrates for millimeter-wave applications, etc.

[0043] If the dielectric properties, especially the dielectric tangent, of existing silicon dioxide powder or quartz glass cloth can be arbitrarily adjusted, it can be widely used as a sealing material for high-speed communication semiconductors, which are expected to grow significantly in the future, and as a reinforcing material or filler for high-speed communication substrates and antenna substrates. Furthermore, the inventors have discovered a means to arbitrarily adjust the dielectric properties of raw materials (quartz glass cloth or silicon dioxide powder) as described below, and applied it to the present invention.

[0044] [Resin substrate] This invention relates to a resin substrate comprising organic resin and quartz glass cloth, characterized in that: The dielectric tangent of the aforementioned organic resin measured at 10 GHz was 0.0002 to 0.0020, and the ratio of the dielectric tangent at 40 GHz to that at 10 GHz (40 GHz / 10 GHz ratio) was 0.4 to 0.9. The dielectric tangent of the aforementioned quartz glass cloth measured at 10 GHz was 0.0001 to 0.0015, and the ratio of the dielectric tangent at 40 GHz to that at 10 GHz (40 GHz / 10 GHz ratio) was 1.2 to 2.0. The aforementioned resin substrate has a dielectric tangent of 0.0001 to 0.0020 at 10 GHz, and the ratio of the dielectric tangent at 40 GHz to the dielectric tangent at 10 GHz (40 GHz / 10 GHz ratio) is 0.8 to 1.2.

[0045] Here, the ratio of the dielectric tangent at 40 GHz to that at 10 GHz (40 GHz / 10 GHz ratio) is an indicator of the frequency dependence of the dielectric tangent. If it is less than 1, it means that the dielectric tangent decreases as the frequency increases (i.e., negative correlation). Conversely, if it is greater than 1, it means that the dielectric tangent increases as the frequency increases (i.e., positive correlation).

[0046] In this invention, the 40GHz / 10GHz ratio of the organic resin is 0.4 to 0.9, preferably 0.45 to 0.90. The 40GHz / 10GHz ratio of the quartz glass cloth is 1.2 to 2.0, preferably 1.3 to 1.9. The 40GHz / 10GHz ratio of the resin substrate is 0.8 to 1.2, preferably 0.85 to 1.20. If any of the above 40GHz / 10GHz ratios is outside the necessary range, the frequency dependence in the high-frequency region becomes too large, making it impossible to transmit a stable and high-quality signal.

[0047] If this is a resin substrate, even if the distribution of resin or glass cloth above and below each wiring is uneven, the organic resin between the wirings, which has a negative correlation with the frequency dependence of dielectric tangent (that is, the organic resin whose dielectric tangent value decreases as the frequency increases), and the raw materials, which have a positive correlation with the frequency (that is, the dielectric tangent value increases as the frequency decreases), can be adjusted and combined to create a resin substrate with low frequency dependence of dielectric properties. The propagation time is the same, and a stable and high-quality signal can be transmitted.

[0048] Furthermore, by combining an organic resin with a negative correlation between the frequency dependence of the dielectric tangent and a quartz glass cloth and silicon dioxide powder with a positive correlation between the frequency dependence of the dielectric tangent and the dielectric tangent through arbitrary adjustment, a resin substrate is formed that has dielectric properties with low frequency dependence, is expected to grow significantly in the future, has no transmission loss, and is suitable for low-dielectric substrates for high-speed communication in millimeter waves.

[0049] The components (compositions) constituting the resin substrate of the present invention will be described below.

[0050] [Quartz Glass Cloth] Regarding the material of the quartz glass cloth used in this invention, naturally occurring quartz with few impurities or synthetic quartz using silicon tetrachloride as a raw material can be used.

[0051] The concentration of impurities in the quartz glass material is preferably as follows: the total amount of alkali metals Na (sodium), K (potassium), and Li (lithium) is less than 10 ppm; boron (boron) is less than 1 ppm; phosphorus (phosphorus) is less than 1 ppm; and to prevent malfunctions caused by radiation, the content of uranium (uranium) or thorium (thorium) is less than 0.1 ppb. The concentration of the above impurities can be determined by atomic absorption spectrophotometry.

[0052] The quartz glass cloth of the present invention can be manufactured by using quartz ingots obtained by the following general manufacturing method as raw materials to manufacture filaments and yarns, and then weaving them.

[0053] Quartz ingots can be manufactured by electrofusion, flame melting, direct synthesis, plasma synthesis, fume synthesis, or sol-gel method using naturally occurring quartz as raw material, or silicon tetrachloride as raw material.

[0054] For example, the quartz wire with a diameter of 100μm to 300μm used in this invention can be manufactured by melting the ingot at 1700 to 2300°C, stretching it, and then winding it up. Furthermore, in this specification, the filamentous single fiber obtained by stretching the above-mentioned quartz filament is defined as quartz glass filament, the quartz glass filament bundled together is defined as quartz glass rope strand, and the quartz glass filament bundled together and further twisted together is defined as quartz glass yarn.

[0055] When the quartz glass filament is used, its diameter is preferably 3μm to 20μm, and more preferably 3.5μm to 9μm. Examples of methods for manufacturing quartz glass filaments include electro-melting of the quartz filament and extending it using an oxyhydrogen flame. However, if the diameter of the quartz glass filament is 3μm to 20μm, the manufacturing method is not limited to these methods.

[0056] The aforementioned quartz glass filaments are bundled together to form quartz glass strands, with 10 to 400 strands being more preferably 40 to 200 strands.

[0057] Furthermore, the quartz glass cloth used in this invention can be manufactured by weaving the aforementioned quartz glass yarn or rope strands. There are no particular limitations on the weaving method of the quartz glass cloth; for example, weaving methods using a rapier loom, shuttle loom, or air-jet loom can be listed.

[0058] Low-dielectric quartz glass cloth The quartz glass cloth used in this invention only needs to have a dielectric tangent of 0.0001 to 0.0015 measured at 10 GHz, and a dielectric tangent ratio (40 GHz / 10 GHz ratio) of 1.2 to 2.0 at 40 GHz. Other characteristics are not particularly limited. However, it is preferable to use a low-dielectric quartz glass cloth based on the following insights.

[0059] The inventors have discovered that by using the following low-dielectric quartz glass cloth, the dielectric tangent value or frequency dependence of the dielectric tangent can be arbitrarily adjusted in the range of 1 GHz to 50 GHz. The aforementioned low-dielectric quartz glass cloth is made by removing the strain layer on the surface of the fibers after the quartz glass cloth with a dielectric tangent of less than 0.0015 at 10 GHz in the high-frequency region, a dielectric constant of 3.2 to 3.9, and a tensile strength of 2.7 N / 25 mm or more in terms of cloth weight (g / m 2) is subjected to high-temperature treatment at a temperature of 500°C or higher.

[0060] In this invention, it is preferable to use the following low-dielectric quartz glass cloth, which is made by heating the above-mentioned quartz glass cloth at high temperature to arbitrarily adjust the hydroxyl groups present in the quartz, dissolving and removing the strain layer generated on the surface of the quartz glass, and treating the surface of the quartz glass with a coupling agent or the like.

[0061] The heating temperature for removing hydroxyl groups from quartz can be 500℃ to 1500℃, and the heating time can be 10 minutes to 24 hours. Furthermore, the cooling process after heating to room temperature can be either slow or rapid, depending on the conditions. Sometimes, molten quartz glass may crystallize locally, so the heating temperature or cooling conditions should be optimized. As for the heating atmosphere, air or inert gases such as nitrogen are all acceptable, and it can be carried out under normal pressure, vacuum, or reduced pressure; there are no particular limitations, but cost considerations usually preclude it from being performed in air. The degree of hydroxyl group reduction caused by the heat treatment can be analyzed using infrared spectroscopy to confirm whether the desired dielectric properties have been achieved.

[0062] By adjusting the heating temperature and heating time using the aforementioned steps, without changing the dielectric constant, the dielectric tangent at 10 GHz can be freely controlled within the range of 0.0001 to 0.0015, which is typical for quartz. For the fabrication of a low-dielectric substrate, the dielectric tangent can be set to 0.0001 to 0.0010, more preferably 0.0001 to 0.0008, and further preferably 0.0001 to 0.0005.

[0063] Even after the above treatment, the dielectric constant of the quartz glass cloth remains unchanged compared to before the treatment, exhibiting excellent properties of 3.2 to 3.9. Furthermore, regarding the dielectric properties (dielectric tangent, dielectric constant) of quartz glass cloth, a network analyzer can be connected to an SPDR (Split Post Dielectric Resonators) resonator to perform measurements at a predetermined frequency.

[0064] Quartz glass cloth sometimes experiences a decrease in strength when heat-treated at temperatures above 500°C. This can be attributed to the slight residual strain on the surface layer of the quartz glass cloth after high-temperature heat treatment, which becomes the starting point for breakage. Therefore, the quartz glass cloth used in this invention is preferably a low-dielectric quartz glass cloth whose strength is restored by removing this strain layer.

[0065] Regarding the removal of the strain layer on quartz glass cloth, the strain layer can be easily removed by immersing the cloth in an etching solution or similar solution.

[0066] During the manufacturing of prepreg, a surface treatment using a silane coupling agent can be performed to ensure a strong bond between the resin and the surface of the quartz glass cloth. The surface treatment is performed after the high-temperature treatment and etching of the quartz glass cloth, followed by cleaning of the quartz glass cloth, and then coating the surface of the quartz glass cloth with a silane coupling agent.

[0067] As a silane coupling agent, known silane coupling agents can be used, preferably alkoxysilanes. As a representative silane coupling agent, it is preferably selected from one or more of the following groups: 3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBM-903), 3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBE-903), N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBM-603), N-2-(aminoethyl)-3-aminopropyltriethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBM-603), N-2-(aminoethyl)-3-aminopropyltriethoxysilane (Shin-Etsu Chemical Industry Co., Ltd.). Amine-based silane coupling agents such as KBE-903 (manufactured by Shin-Etsu Chemical Industry Co., Ltd.); vinyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBM-1003), vinyltriethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBE-1003), 3-methylpropenyloxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBM-503), 3-methylpropenyloxypropyltriethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBE-503), p-styrenetrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBE-503), p-styrenetrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.); Silane coupling agents containing unsaturated groups, such as KBM-1403 (manufactured by Shin-Etsu Chemical Industry Co., Ltd.); silane coupling agents containing fluorine atoms, such as trifluoropropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBM-7103) and perfluoropolyether-containing trialkoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade names: X-71-195, KY-1901, KY-108); glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBM-403) and glycidoxypropyltriethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBM-1403); glycidoxypropyltriethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBM-1403); and others. The following are examples of silane coupling agents containing functional groups or organic groups other than those mentioned above: KBE-403, 3-mercaptopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBM-803), 3-isocyanate propyltriethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: KBE-9007), 3-trimethoxysilylpropylsuccinic anhydride (manufactured by Shin-Etsu Chemical Industry Co., Ltd.; trade name: X-12-967C); or oligomers composed of the above-mentioned amino-based silane coupling agents and silane coupling agents containing unsaturated groups; particularly preferably, amino-based silane coupling agents or silane coupling agents containing unsaturated groups.

[0068] Regarding the concentration of the aforementioned silane coupling agent, it is typically used as a dilute aqueous solution between 0.1% and 5% by mass, with a concentration between 0.1% and 1% by mass being particularly effective. By using this type of quartz glass cloth, not only does the aforementioned silane coupling agent adhere uniformly, providing a more uniform protective effect on the surface of the quartz glass cloth, and the operation is easy, but it also allows for uniform and uneven coating of the resin used in the preparation of prepregs.

[0069] [Organic resin] The organic resin contained in the resin substrate of the present invention only needs to have a dielectric tangent of 0.0002 to 0.0020 measured at 10 GHz, and a dielectric tangent ratio (40 GHz / 10 GHz ratio) of 0.4 to 0.9 at 40 GHz. Other characteristics are not particularly limited. Organic resins used in resin substrates such as low-dielectric substrates for high-speed millimeter-wave communication can be any thermosetting or thermoplastic low-dielectric-value organic resins with a dielectric constant of 2.0 to 3.5, a dielectric tangent (10 GHz) of 0.002 or less, and ideally 0.0018 or less. Alternatively, various resins can be mixed and used together.

[0070] Examples of thermoplastic resins include polyphenylene ether, polyetheretherketone, polyetherketone, polyether ether, and fluoropolymers. Fluoropolymers are particularly desirable for their low dielectric properties. A preferred fluoropolymer is selected from at least one group consisting of polytetrafluoroethylene (PTFE), tetrafluoroethylene-ethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), chlorotrifluoroethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride (PVdF), and thermoplastic fluoropolymers (THV) composed of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride monomers. In terms of dielectric tangent, polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), or tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA) are particularly desirable.

[0071] Examples of thermosetting resins include epoxy resins, allylated epoxy resins, maleimide resins, bismaleimide resins, cyanate ester resins, and cyclopentadiene-styrene copolymer resins. Among these, bismaleimide resins represented by the following general formula can be used as organic resins suitable for low dielectricization. In the aforementioned formula, A independently represents a tetravalent organic group containing an aromatic ring or an aliphatic ring, B is a divalent alkyl chain with an aliphatic ring containing heteroatoms and having 6 to 18 carbon atoms, Q independently represents a straight-chain alkyl chain with 6 or more carbon atoms, R independently represents a straight-chain or branched alkyl chain with 6 or more carbon atoms, n represents a number from 1 to 10, and m represents a number from 0 to 10.

[0072] Representative bismaleimide resins include the SLK series (such as SLK-6895, SLK-3000, and SLK-2600 manufactured by Shin-Etsu Chemical Co., Ltd.). Additionally, thermosetting cyclopentadiene-styrene copolymer resins can also be used as high-heat-resistant, low-dielectric resins. A representative example is the SLK-250 series (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0073] [Silicon dioxide powder] The resin substrate of the present invention may contain inorganic powder as needed, preferably silicon dioxide powder. From the viewpoint of low dielectric constant, it is particularly preferred to use silicon dioxide powder with a low dielectric tangent (low dielectric silicon dioxide powder). The silica powder used in this invention is not particularly limited, and can be silica powder with a dielectric tangent of 0.0001 to 0.0015 at 10 GHz. Examples include silica powder with an average particle size of 0.1 μm to 30 μm, a dielectric constant of 3.2 to 3.9, and a dielectric tangent (10 GHz) of 0.0001 to 0.0015. Low-dielectric silica powder containing the following components in part or all of its interior and surface can be used: metals and / or oxides selected from aluminum, magnesium, and titanium, with a metal conversion of 200 ppm or less, and the contents of alkali metals and alkaline earth metals, each of which are 10 ppm or less. Furthermore, the aforementioned silica powder with B (boron) content below 1 ppm, P (phosphorus) content below 1 ppm, and U (uranium) and Th (thorium) content below 0.1 ppb can also be used as low dielectric silica powder. Furthermore, the average particle size can be calculated as the mass average value D50 (i.e., the particle size or median diameter when the cumulative mass reaches 50%) in particle size distribution determination using laser diffraction. Additionally, the concentration of impurities can be determined using atomic absorption spectrophotometry, similar to that used for quartz glass.

[0074] [Low Dielectric Silicon Dioxide Powder] The low-dielectric silicon dioxide powder used in this invention is preferably obtained by heating silicon dioxide powder at a temperature of 500°C to 1500°C to reduce its dielectric properties, and then etching the surface of the silicon dioxide powder with an alkaline aqueous solution, or more preferably alkaline electrolyzed water with a pH value of 12 or higher.

[0075] In this invention, the preferred hydroxyl (Si-OH) content of the silicon dioxide powder system is 300 ppm or less. With this content, a sufficiently low dielectric tangent can be obtained. Through the above-described heat treatment, the amount of hydroxyl groups in the silicon dioxide powder becomes 300 ppm or less, preferably 280 ppm or less, and even more preferably 150 ppm or less, thus becoming a low-dielectric silicon dioxide powder with low dielectric tangent characteristics.

[0076] The low-dielectric silicon dioxide powder system used in this invention has an average particle size of 0.1 to 30 μm, preferably a maximum particle size of 100 μm or less. When used as a filler for a substrate for high-speed communication, the average particle size is 0.1 to 5 μm and the maximum particle size is 20 μm, and more ideally it is 0.1 to 3 μm and the maximum particle size is 10 μm or less.

[0077] The low-dielectric silica powder is heat-treated at a temperature of 500°C to 1500°C, and the dielectric constant of the silica powder is 3.2 to 3.9, the dielectric tangent (10 GHz) is 0.0001 to 0.0015, more preferably 0.0001 to 0.0010, and even more preferably 0.0001 to 0.0008.

[0078] By heat-treating silicon dioxide powder at temperatures above 500°C, the amount of hydroxyl groups in the silicon dioxide powder particles can be adjusted, thereby arbitrarily adjusting the frequency dependence of the dielectric tangent. Furthermore, in cases where a strain layer forms on the particle surface due to heat treatment, resulting in a decrease in strength, the low-dielectric silicon dioxide powder used in this invention is ideally used after removing this strain layer. Regarding the removal of the strain layer from the silicon dioxide powder, it can be easily removed by immersing the silicon dioxide powder in an etching solution, similar to the method described above for quartz glass cloth.

[0079] When manufacturing prepreg by coating the surface of silica powder with a silane coupling agent, the resin can be firmly bonded to the surface of the quartz glass cloth or silica powder.

[0080] As a silane coupling agent, the known silane coupling agents used in the aforementioned quartz glass cloth can be used.

[0081] Especially when using a resin with a low dielectric constant and low dielectric tangent as the matrix resin of the substrate, the resin is only filled in the basket holes (the gaps between the cross and longitudinal fibers of the glass cloth), thus increasing the difference in dielectric properties between the resin and the quartz glass cloth. Therefore, it is preferable to add silica powder to make the dielectric constant approximate that of the quartz glass cloth. The amount of silica powder relative to 100 parts by mass of the total resin content is 0 to 1000 parts by mass, preferably 50 to 800 parts by mass, and even more preferably 80 to 700 parts by mass. If it is 50 parts by mass or more, the dielectric properties can be sufficiently adjusted, the coefficient of thermal expansion (CTE) of the cured material will not be too large, and sufficient strength can be obtained, so it is preferable to add 50 parts by mass or more. However, depending on the type of organic resin or its application, non-additive systems may also be used. If the content is less than 1000 parts by weight, it will not lose its flexibility or produce poor appearance during the manufacture of prepreg. Furthermore, the silica powder is preferably contained in the range of 10% to 90% by weight, and especially 15% to 85% by weight, of the total resin. The silica powder may also be doped with silica powders of different average particle sizes to improve properties such as flowability or processability.

[0082] This low-dielectric silicon dioxide powder, when used in conjunction with the aforementioned quartz glass cloth, especially low-dielectric quartz glass cloth, is suitable as a filler for substrates such as high-speed communication substrates and antenna substrates.

[0083] [Other ingredients] In addition to the components described above, the resin substrate of the present invention may also contain the silane coupling agent or, as needed, any components such as dyes, pigments, flame retardants or adhesives.

[0084] <Resin substrates with low frequency dependence dielectric properties> The resin substrate of the present invention, as described above, comprises a specific organic resin and a specific quartz glass cloth. The resin substrate is characterized in that: the dielectric tangent of the aforementioned resin substrate at 10 GHz is 0.0001 to 0.0020, and the ratio of the dielectric tangent at 40 GHz to the dielectric tangent at 10 GHz (40 GHz / 10 GHz ratio) is 0.8 to 1.2.

[0085] The present invention relates first to a resin substrate having dielectric properties with low frequency dependence, the resin substrate comprising: an organic resin, wherein the frequency dependence of the dielectric tangent of the cured resin or thermoplastic resin is negatively correlated at 1 GHz to 50 GHz; and a silica powder alone or added as needed, wherein the frequency dependence of the dielectric tangent is positively correlated.

[0086] This invention relates to a wiring board material such as a prepreg and multilayer board, which is a resin substrate (low-dielectric substrate) comprising: a quartz glass cloth having a dielectric tangent positively correlated with frequency and a low-dielectric resin having a negative correlation, and silicon dioxide powder having a positive correlation added as needed; and capable of transmitting stable signals with stable dielectric properties in a wide frequency band from 1 GHz to 50 GHz. Furthermore, this invention relates to a multilayer printed circuit board with a low dielectric constant and low dielectric tangent, which is optimally suited for high-frequency signal transmission characteristics; a printed circuit board; and resin compositions, prepregs, multilayer boards, antennas, radomes, etc., used to manufacture the printed circuit board.

[0087] -Low-dielectric substrate with low frequency dependence- The low-dielectric substrate is a multilayer substrate made of organic resin prepreg (low-dielectric multilayer substrate), which contains the aforementioned quartz glass cloth (preferably low-dielectric quartz glass cloth) and organic resin (preferably an organic resin with low dielectric properties) as essential components, and may contain silicon dioxide powder as an optional component. In the low-dielectric multilayer substrate, the thickness of the insulating layer can be appropriately selected according to its application, etc., and is not particularly limited, preferably 20μm to 2000μm, more preferably 50μm to 1000μm.

[0088] -Manufacturing method of low-dielectric composite substrate- There are no particular limitations on the manufacturing method of low-dielectric composite substrates. For example, a method can be listed as follows: obtaining a low-dielectric composite substrate by impregnating an organic resin composition with a prepreg obtained from a quartz glass cloth; or obtaining a low-dielectric composite substrate by heating and pressing a resin film and a quartz glass cloth together.

[0089] Regarding the low-dielectric composite substrate, an organic resin with the aforementioned low-dielectric properties (an organic resin composition containing and / or not containing silicon dioxide powder) is impregnated in a quartz glass cloth in a dissolved and dispersed state in a solvent. The solvent is then removed by evaporation from the quartz glass cloth to obtain a prepreg. The obtained prepreg is then subjected to pressure and heat curing to obtain the low-dielectric composite substrate. Here, when silicon dioxide powder is present, the amount of silicon dioxide powder is preferably in the range of 50 to 800 parts by mass relative to 1000 parts by mass of the organic resin (0 to 1000 parts by mass).

[0090] -solvent- When manufacturing low-dielectric laminate substrates, there are no particular limitations as long as the organic resin composition can be dissolved and dispersed, and evaporation can be carried out at a temperature that keeps the composition in an uncured or semi-cured state. Examples of solvents include those with boiling points of 50°C to 200°C, preferably 80°C to 150°C. Specific examples of solvents include: non-polar hydrocarbon solvents such as toluene, xylene, hexane, and heptane; and polar hydrocarbon solvents such as ethers and esters. Furthermore, for organic resins that are difficult to dissolve, an aqueous dispersion can be prepared using a surfactant and water. Regarding the amount of solvent used, there are no particular limitations as long as it is sufficient to dissolve and disperse the organic resin composition and impregnate the resulting solution or dispersion in the quartz glass cloth. Preferably, it is 10 to 200 parts by mass relative to 100 parts by mass of the organic resin composition, and more preferably 20 to 100 parts by mass.

[0091] Regarding the solution or dispersion of the above-mentioned organic resin composition, for example, quartz glass cloth is impregnated in the solution or dispersion, and the solvent is removed in a drying oven at a preferred temperature of 50°C to 150°C, more preferably 60°C to 120°C, thereby obtaining an organic resin prepreg. In the case of an aqueous dispersion, in order to remove the surfactant, it is preferable to further heat at 300°C to 400°C for 5 minutes to 1 hour.

[0092] The obtained prepreg can be overlapped in a number of sheets corresponding to the thickness of the insulating layer, and then pressurized and heated to form a multilayer substrate. Alternatively, metal foil can be overlapped on the prepreg and pressurized and heated using a vacuum press or similar device to produce a metal-clad multilayer substrate. There are no particular limitations on the metal foil used, but copper foil is preferred from an electrical and economic perspective. Printed wiring boards can be obtained by processing the metal-clad multilayer substrate using conventional methods such as subtractive processing or hole-making.

[0093] In cases where thermoplastic resins are not easily soluble in solvents, prepregs can be made by heating and pressing a resin film onto a quartz glass cloth. In this case, copper foil can also be used.

[0094] For example, in the fabrication of fluoropolymer substrates, there is a method of pressing a pre-formed and surface-treated fluoropolymer film with glass cloth and copper foil under heat. Hot pressing under heat is typically performed at a temperature ranging from 250 to 400°C for 1 to 20 minutes and a pressure of 0.1 MPa to 10 MPa. While the hot pressing temperature depends on the softening temperature of the fluoropolymer, excessively high temperatures may cause resin exudation or uneven thickness; therefore, it is preferable to keep the temperature below 340°C, and more preferably below 330°C. Hot pressing can be performed in batches using a press, or continuously using a high-temperature laminator. To prevent air entrainment when using a press, and to prevent fluoropolymer from easily entering the glass cloth, a vacuum press is preferred.

[0095] In addition, when using an aqueous dispersion of polytetrafluoroethylene (PTFE), a predetermined amount of silica powder is pre-mixed into the aqueous dispersion to form a slurry, which is then impregnated with quartz glass cloth and dried, thereby obtaining quartz glass cloth containing fluororesin and silica powder.

[0096] The quartz glass cloth obtained here is pressurized at the above-mentioned temperature and time to produce a prepreg obtained from fluororesin. Since the aqueous dispersion system of fluororesin micropowder contains organic surfactants, it is preferable to heat at 300-400°C for 5 minutes to 1 hour to remove the surfactants. The fluororesin substrate can be manufactured using the above manufacturing method. The fluororesin substrate contains fluororesin, which is the starting material of this invention.

[0097] The surface-treated fluoropolymer film, when used as a monomer, cannot adequately bond to copper foil with low surface roughness. It also bleeds out of the copper foil during hot pressing and cannot achieve uniform thickness. However, as mentioned above, when it is combined with quartz glass cloth, the linear expansion rate is significantly reduced, thereby reducing resin bleed-out and exhibiting high adhesion to copper foil with a surface roughness Ra of less than 0.2 μm.

[0098] The laminate is constructed by alternately laminating n fluororesin films and n-1 quartz glass cloths (n being an integer from 2 to 10) between two copper foils, but the value of n is preferably 8 or less, and even more preferably 6 or less. The linear expansion rate in the X and Y directions of the low-dielectric laminate substrate can be changed by altering the thickness of the fluororesin film, the type of quartz glass cloth, and the value of n. The linear expansion rate is preferably in the range of 5 ppm / ℃ to 50 ppm / ℃, and even more preferably in the range of 10 ppm / ℃ to 40 ppm / ℃. If the linear expansion rate of the dielectric layer is 50 ppm / ℃ or less, the adhesion between the copper foil and the dielectric layer will not decrease, and no defects such as warping or undulation of the substrate will occur after copper foil etching.

[0099] The electrode pattern of the metal-clad laminate substrate can be made by known methods, such as etching the copper-clad laminate substrate, which has a low-dielectric laminate substrate and copper foil on one or both sides of the laminate substrate. [Example]

[0100] The present invention will now be specifically described using examples and comparative examples, but the present invention is not limited thereto. Furthermore, unless otherwise specified, the following methods shall be used to determine the following characteristic values ​​(tensile strength, dielectric tangent (tanδ), dielectric constant, and average particle size).

[0101] 1. Determination of tensile strength The tensile strength was measured according to "7.4 Tensile Strength" of JIS (Japanese Industrial Standards) R3420:2013 "General Test Methods for Glass Fibers".

[0102] 2. Determination of dielectric tangent 2.1 Glass cloth, organic resin, resin substrate Except where specifically stated otherwise, a network analyzer (MS46122B manufactured by Anritsu Corporation) was connected to an SPDR resonator (manufactured by Keysight Technologies Corporation) to measure the dielectric tangent of the sample at a predetermined frequency.

[0103] 2.2 Silicon dioxide powder (1) 100 parts by weight of silica powder were mixed with 100 parts by weight of SLK-3000 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a low-dielectric maleimide resin and 2.0 parts by weight of dicumyl peroxide (manufactured by Nippon Oil Co., Ltd.) as a free radical polymerization initiator and used as a curing agent, and dispersed and dissolved to prepare a varnish. At this time, the silica powder accounted for 33.3% by volume relative to the resin. Similarly, silica powder was prepared by adjusting the above 100 parts by weight of resin to 0%, 11.1%, and 66.7% by volume to prepare varnishes. The prepared varnish was spread to a thickness of 200 μm using a bar coater, and then placed in a dryer at 80°C for 30 minutes to remove the anisole solvent, thereby preparing an uncured maleimide resin composition.

[0104] (2) The prepared uncured maleimide resin components were added to a 60mm×60mm×100μm mold and cured by hand pressing at 180℃ for 10 minutes and 30MPa. Then, the resin was completely cured by using a desiccator at 180℃ for 1 hour to produce a resin-cured sheet. The resin-cured sheet was cut into 50mm×50mm pieces, and the dielectric tangent at a frequency of 10GHz was measured using an SPDR dielectric resonator (manufactured by Keysight Technologies Inc.).

[0105] (3) Based on the graph obtained by taking the volume % of silicon dioxide powder on the horizontal axis and the measured dielectric tangent on the vertical axis, a straight line is made of volume % of silicon dioxide powder vs. dielectric tangent. This straight line is interpolated, and the dielectric tangent of 100% of silicon dioxide powder is set as the value of the dielectric tangent of silicon dioxide powder.

[0106] Furthermore, while there are measuring instruments that can directly measure silica powder, the silica powder is filled into the measuring pot for measurement, making it difficult to remove the air mixed in. This is especially true for silica powder with a large specific surface area, where the influence of air mixing is significant, making the process even more difficult. Therefore, in order to eliminate the influence of air mixing and obtain values ​​close to the actual usage conditions, this invention uses the aforementioned measurement method to determine the dielectric tangent of silica powder.

[0107] 3. Determination of dielectric constant For glass cloth, organic resin, and resin substrate, unless otherwise specified, the above-mentioned network analyzer is connected to the SPDR resonator to determine the dielectric constant of the sample at a predetermined frequency. For silicon dioxide powder, the dielectric tangent was measured together with the above-mentioned dielectric tangent.

[0108] 4. Determination of average particle size The particle size distribution was measured using a laser diffraction particle size distribution measuring device, and the mass average value D50 in the particle size distribution was taken as the average particle size.

[0109] Manufacturing of Low-Dielectric Quartz Glass Cloth (Preparation Example 1: Manufacturing Example of Quartz Glass Cloth (SQ1)) While extending quartz glass filaments at high temperature, a quartz glass fiber binding agent is applied to create a quartz glass rope strand composed of 200 quartz glass filaments with a diameter of 7.0 μm. Subsequently, the obtained quartz glass rope strand is twisted in 25 mm increments of 0.2 turns to produce quartz glass yarn. The obtained quartz glass yarn was placed on an air-jet loom to weave a plain-woven quartz glass cloth with a warp density of 60 threads / 25mm and a cross warp density of 58 threads / 25mm. The quartz glass cloth had a thickness of 0.086mm and a weight of 85.5g / m². The fiber-binding agent was removed by heat treatment at 400°C for 10 hours. Furthermore, the quartz glass cloth with a width of 1.3 m and a length of 2000 m manufactured in Preparation Example 1 was designated as SQ1. The dielectric tangent and dielectric constant of SQ1 were measured at different frequencies of 10 GHz, 28 GHz, and 40 GHz, as shown in Table 1 below. Furthermore, the tensile strength of the quartz glass cloth is 80N / 25mm.

[0110] (Preparation Example 2: Manufacturing Example of Quartz Glass Cloth (SQ2)) The quartz glass cloth with a width of 1.3 m and a length of 2000 m manufactured in Preparation Example 1 was placed in an electric furnace set to 700°C and heated for 5 hours. After heating, it was cooled to room temperature for 8 hours. The quartz glass cloth was then immersed in alkaline electrolyzed water with a pH of 13 heated to 40°C for 48 hours for etching. After etching, it was washed with deionized water and dried, thereby producing a low-dielectric, high-strength quartz glass cloth. This quartz glass cloth was designated SQ2. The dielectric tangent and dielectric constant of SQ2 were measured at different frequencies in the same manner as in Preparation Example 1, as shown in Table 1 below. Furthermore, the tensile strength of the quartz glass cloth is 110N / 25mm.

[0111] (Preparation Example 3: Manufacturing Example of Quartz Glass Cloth (SQ3)) The quartz glass cloth with a width of 1.3 m and a length of 2000 m manufactured in Preparation Example 1 was placed in an electric furnace set to 700°C and heated for 2 hours. After heating, it was cooled to room temperature for 8 hours. The cooled quartz glass cloth was then immersed in alkaline electrolyzed water with a pH of 13 heated to 40°C for 48 hours for etching. After etching, it was washed with deionized water and dried, thereby producing a low-dielectric, high-strength quartz glass cloth. This quartz glass cloth was designated SQ3. The dielectric tangent and dielectric constant of SQ3 were measured at different frequencies in the same manner as in Preparation Example 1, as shown in Table 1 below. Furthermore, the tensile strength of the quartz glass cloth is 105 N / 25 mm.

[0112] [Table 1] Preparation Example 1 2 3 Quartz glass cloth No. SQ1 SQ2 SQ3 Measurement frequency Dielectric tangent Dielectric constant Dielectric tangent Dielectric constant Dielectric tangent Dielectric constant 10GHz 0.0011 3.3 0.0002 3.3 0.0007 3.4 28GHz 0.0013 3.3 0.0002 3.3 0.0009 3.4 40GHz 0.0015 3.3 0.0003 3.3 0.0010 3.4 40GHz / 10GHz *1 1.4 1.0 1.5 1.0 1.4 1.0 *1: The ratio of dielectric tangent at 40 GHz to dielectric tangent at 10 GHz

[0113] (Treatment of metallic impurities and silane coupling agents in the quartz glass cloths manufactured in Preparation Examples 1 to 3) The alkali metals in the quartz glass cloth were all 0.5 ppm in SQ1, SQ2, and SQ3, phosphorus was 0.1 ppm, and the contents of U and Th were 0.1 ppb. The contents of each element were determined by atomic absorption spectrometry (metal conversion). Quartz glass cloths SQ1, SQ2, and SQ3 were immersed in a 0.5% by mass aqueous solution of silane coupling agent KBM-903 (trade name: manufactured by Shin-Etsu Chemical Industry Co., Ltd., 3-aminopropyltrimethoxysilane) for 10 minutes, and then heated and dried at 110°C for 20 minutes for surface treatment.

[0114] <Manufacturing of Low Dielectric Silica Powder> (Preparation Example 4) Five kilograms of silica powder (SO-25H manufactured by Admatechs) with an average particle size of 0.5 μm and a dielectric tangent of 0.0011 (10 GHz) were placed in an alumina container and heated in air at 1100°C for 5 hours in a muffle furnace (manufactured by As-one). The mixture was then cooled to room temperature for 6 hours to obtain silica powder. The heat-treated silica powder was then placed in a plastic container containing 20 L of alkaline electrolyzed water with a pH of 13. The container was heated to 60°C and stirred for 2 hours to remove the strain layer on the particle surface. The silica powder was then separated using a centrifuge, washed with methanol, and dried. The dried silica powder was pulverized into low-dielectric silica powder using a ball mill. The dielectric tangent and dielectric constant of the low-dielectric silica powder were measured at different frequencies in the same manner as in Preparation Example 1, and the values ​​are shown in Table 2 below. The low dielectric silica powder (S1) obtained here was surface treated with silane coupling agent KBM-503 (manufactured by Shin-Etsu Chemical Industry Co., Ltd., 3-methylpropenyloxypropyltrimethoxysilane) and used to manufacture resin substrates.

[0115] (Preparation Example 5) Five kilograms of silica powder (SO-25H manufactured by Admatechs) with an average particle size of 0.5 μm and a dielectric tangent of 0.0011 (10 GHz) were placed in an alumina container and heated in air at 700°C for 5 hours in a muffle furnace (manufactured by As-one). The powder was then cooled to room temperature for 6 hours to obtain silica powder. The cooled silica powder was then pulverized into low-dielectric silica powder using a ball mill. The dielectric tangent and dielectric constant of this low-dielectric silica powder were measured at different frequencies, similar to those in Preparation Example 1, and are shown in Table 2 below. The low dielectric silica powder (S2) obtained here was surface treated with silane coupling agent KBM-503 (manufactured by Shin-Etsu Chemical Co., Ltd.) and used to manufacture resin substrates.

[0116] (Preparation Example 6) The dielectric tangent and dielectric constant of untreated silica powder (SO-25H manufactured by Admatechs) with an average particle size of 0.5 μm and a dielectric tangent of 0.0011 (10 GHz) were measured at different frequencies in the same manner as in Preparation Example 1, and are shown in Table 2 below.

[0117] [Table 2] Preparation Example 4 5 6 Low dielectric silicon dioxide No. S1 S2 SO-25H Measurement frequency Dielectric tangent Dielectric constant Dielectric tangent Dielectric constant Dielectric tangent Dielectric constant 10GHz 0.0002 3.4 0.0007 3.4 0.0011 3.4 28GHz 0.0003 3.4 0.0009 3.4 0.0014 3.4 40GHz 0.0004 3.4 0.0010 3.4 0.0015 3.4 40GHz / 10GHz *1 2 1.0 1.4 1.0 1.4 1.0 *1: The ratio of dielectric tangent at 40 GHz to dielectric tangent at 10 GHz

[0118] <Dielectric tangent and dielectric constant of organic resins> (A) Bismaleimide resin: SLK-3000 (manufactured by Shin-Etsu Chemical Co., Ltd.) Maleimine compounds containing straight-chain extended alkyl groups, represented by the following formula Similar to Preparation Example 1, the dielectric tangent and dielectric constant of the SLK-3000 film were measured at different frequencies. The results are shown in Table 3.

[0119] (B) Fluoropolymer (PFA) Similar to Preparation Example 1, the dielectric tangent and dielectric constant of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) film (TFE / PPVE = 98.5 / 1.5 (mol%), MFR (Melt Flow Rate): 14.8 g / 10 min, melting point: 305 °C) were measured at different frequencies. The results are shown in Table 3.

[0120] (C) Fluoropolymer (PTFE) The dielectric tangent and dielectric constant of the polytetrafluoroethylene (PTFE) film were measured at different frequencies, similar to those in Preparation Example 1. The results are shown in Table 3.

[0121] (D) Maleimide resin: MIR-3000 (manufactured by Nippon Kayaku Co., Ltd.) Similar to Preparation Example 1, the dielectric tangent and dielectric constant of the MIR-3000 film were measured at different frequencies. The results are shown in Table 3.

[0122] [Table 3] Organic resin No. A B C D Organic resin structure, trade name SLK-3000 PFA PTFE MIR-3000 Measurement frequency Dielectric Tangent Dielectric constant Dielectric Tangent Dielectric constant Dielectric Tangent Dielectric constant Dielectric Tangent Dielectric constant 10GHz 0.0016 2.5 0.0010 2.1 0.0002 2.1 0.0031 2.8 28GHz 0.0015 2.5 0.0009 2.1 0.0002 2.1 0.0035 2.8 40GHz 0.0014 2.5 0.0008 2.1 0.0001 2.1 0.0037 2.8 40GHz / 10GHz *1 0.9 1.0 0.8 1.0 0.5 1.0 1.2 1.0 *1: The ratio of dielectric tangent at 40 GHz to dielectric tangent at 10 GHz

[0123] <Preparation of Slurry> (Preparation Example 7) 100 parts by weight of SLK-3000, 100 parts by weight of silica powder SO-25H as shown in Preparation Example 6, and 2 parts by weight of dicumyl peroxide (trade name: Percumyl D, manufactured by Nippon Oil Co., Ltd.) were added to anisole as a solvent. The mixture was premixed using a mixer to prepare a 60% slurry solution, thereby preparing a bismaleimide resin composition slurry with uniformly dispersed filler.

[0124] (Preparation Example 8) 100 parts by weight of MIR-3000 (low dielectric maleimide resin manufactured by Nippon Kayaku Co., Ltd.), 100 parts by weight of silicon dioxide powder (S2) as shown in Preparation Example 5, and 2 parts by weight of dicumyl peroxide (trade name: Percumyl D, manufactured by Nippon Yu Co., Ltd.) were added to anisole as a solvent and premixed using a mixer to prepare a 60% slurry solution, thus preparing a maleimide resin composition slurry with uniformly dispersed filler.

[0125] (Preparation Example 9) 100 parts by weight of MIR-3000 (low dielectric maleimide resin manufactured by Nippon Kayaku Co., Ltd.), 100 parts by weight of silicon dioxide powder (S1) as shown in Preparation Example 4, and 2 parts by weight of dicumyl peroxide (trade name: Percumyl D, manufactured by Nippon Yu Co., Ltd.) were added to anisole as a solvent, and the mixture was premixed using a mixer to prepare a 60% slurry solution, thus preparing a maleimide resin composition slurry with uniformly dispersed filler.

[0126] [Example 1] Fluoropolymer prepreg and laminated substrate Two 50 μm thick tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) films (TFE / PPVE=98.5 / 1.5 (mol%), MFR: 14.8 g / 10 min, melting point: 305 °C) with dielectric constant 2.1 and dielectric tangent of 0.0010 at 10 GHz, and a dielectric constant of 2.1, and one quartz glass cloth (SQ3) as shown in Preparation Example 3, were prepared. The PFA film / quartz glass cloth / PFA film were laminated in sequence, and the films were hot-pressed at 325 °C for 30 minutes using a vacuum press to produce a fluoropolymer substrate. The fluoropolymer substrate also showed no molding defects, resulting in a high-quality fluoropolymer substrate. The dielectric tangent and dielectric constant of this resin substrate were measured. The dielectric tangent and dielectric constant of the fabricated fluoropolymer substrate are shown in Table 4.

[0127] [Example 2] Bismaleimide resin prepreg and laminated substrate The slurry from Preparation Example 7 was impregnated with quartz glass cloth SQ1 and dried at 120°C for 5 minutes to prepare a prepreg. The prepreg was then adjusted to an adhesion content of 46%. Three layers of the prepreg were then laminated and cured in stages at 150°C for 1 hour and then at 180°C for 2 hours using a vacuum press to produce a resin substrate. The dielectric tangent and dielectric constant of the cured resin substrate were measured. The results are shown in Table 4.

[0128] [Example 3] Fluoropolymer substrate containing silicon dioxide powder To 100 parts by mass of an aqueous dispersion of polytetrafluoroethylene (PTFE) microparticles (PTFE aqueous dispersion), consisting of 60% by mass of polytetrafluoroethylene (PTFE) microparticles, 6% by mass of nonionic surfactant, and 34% by mass of water, 40 parts by mass of low-dielectric silica powder (S1) as shown in Preparation Example 4 were added and mixed to adjust the PTFE dispersion containing silica powder. This dispersion was adjusted to an adhesion amount of 46% by mass and then impregnated onto the quartz glass cloth (SQ2) shown in Preparation Example 2. The material was then dried in a drying oven at 100°C for 10 minutes to remove moisture. Subsequently, the prepreg was formed using a vacuum press at 380°C and 1.5 MPa for 5 minutes. Finally, it was placed in a dryer at 380°C for 5 minutes to produce a fluoropolymer substrate. The dielectric tangent and dielectric constant of the fluororesin substrate containing silicon dioxide powder were determined. The results are shown in Table 4. There were no molding defects in the fluoropolymer substrate, resulting in a fluoropolymer substrate with low thermal expansion coefficient and high strength.

[0129] [Comparative Example 1] The slurry from Preparation Example 8 was impregnated with quartz glass cloth SQ1 and dried at 120°C for 5 minutes to prepare a prepreg. The prepreg was then adjusted to an adhesion content of 46%. Three layers of the prepreg were then laminated and cured in stages at 150°C for 1 hour and then at 180°C for 2 hours using a vacuum press to produce a resin substrate. The dielectric tangent and dielectric constant of the cured resin substrate were measured. The results are shown in Table 4.

[0130] [Comparative Example 2] The slurry from Preparation Example 9 was impregnated with quartz glass cloth SQ2 and dried at 120°C for 5 minutes to prepare a prepreg. The prepreg was then adjusted to an adhesion content of 46%. Three layers of the prepreg were then laminated and cured in stages at 150°C for 1 hour and then at 180°C for 2 hours using a vacuum press to produce a resin substrate. The dielectric tangent and dielectric constant of the cured resin substrate were measured. The results are shown in Table 4.

[0131] [Table 4] Example Comparative example Examples & Comparative Examples 1 2 3 1 2 Preparation Example - 7 - 8 9 Quartz glass cloth No. SQ3 SQ1 SQ2 SQ1 SQ2 organic resin PFA SLK-3000 PTFE MIR-3000 MIR-3000 Silicon dioxide powder No. - SO-25H S1 S2 S1 Measurement frequency Dielectric Tangent Dielectric constant Dielectric Tangent Dielectric constant Dielectric tangent Dielectric constant Dielectric Tangent Dielectric constant Dielectric Tangent Dielectric constant 10GHz 0.0008 3.2 0.0014 3.2 0.0002 3.2 0.0021 3.3 0.0020 3.4 28GHz 0.0009 3.2 0.0014 3.2 0.0003 3.2 0.0025 3.3 0.0022 3.4 40GHz 0.0009 3.2 0.0014 3.2 0.0002 3.2 0.0027 3.3 0.0025 3.4 40GHz / 10GHz *1 1.1 1.0 1.0 1.0 1.0 1.0 1.3 1.0 1.3 1.0 *1: The ratio of the dielectric tangent at 40 GHz to the dielectric tangent at 10 GHz

[0132] As shown in Table 4, the resin substrates of embodiments 1 to 3 that satisfy the configuration of the present invention, in addition to having a low dielectric tangent, have a 40GHz / 10GHz ratio of 1.0 to 1.1 and stable dielectric characteristics in a wide frequency band from 1GHz to 50GHz, that is, exhibit dielectric characteristics with low frequency dependence. On the other hand, in Comparative Examples 1 and 2, which are outside the scope of the present invention, the 40GHz / 10GHz ratio of the organic resin that forms the matrix of the resin substrate is 1.3, and the frequency dependence of the dielectric tangent is large. As shown by the above Edward A. Wolff formula, the signal transmission loss increases with the frequency.

[0133] The above results indicate that, for the resin substrate of the present invention, by appropriately combining an organic resin whose dielectric tangent has a negative frequency dependence (i.e., the dielectric tangent decreases as the frequency increases) with a raw material whose dielectric tangent has a positive frequency dependence (i.e., the dielectric tangent increases as the frequency increases), dielectric characteristics with low frequency dependence can be achieved, and stable and high-quality signals can be transmitted without any difference in propagation time.

[0134] In particular, this invention allows for arbitrary variation of the frequency dependence of the dielectric tangent of the quartz glass cloth or silica powder constituting the resin substrate. Therefore, by adapting it to the frequency dependence of the dielectric tangent of the low-dielectric resin contained in the resin substrate, resin substrates with minimal non-uniformity in dielectric properties relative to frequency can be easily and efficiently manufactured. Thus, this invention has extremely high application value in fields such as millimeter-wave high-speed communication low-dielectric substrates where stable dielectric properties are required across a wide frequency band from 1 GHz to 50 GHz.

[0135] Furthermore, the present invention is not limited to the embodiments described above. The embodiments described above are examples, and all embodiments that have substantially the same structure and perform the same effect as the technical concept described in the claims of the present invention are included in the technical scope of the present invention.

[0136] none

[0137] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A resin substrate comprising an organic resin and a quartz glass cloth, characterized in that: the dielectric tangent of the aforementioned organic resin at 10 GHz is 0.0002 to 0.0020, and the ratio of its dielectric tangent at 40 GHz to that at 10 GHz is 0.4 to 0.9; the dielectric tangent of the aforementioned quartz glass cloth at 10 GHz is 0.0001 to 0.0015, and the ratio of its dielectric tangent at 40 GHz to that at 10 GHz is 1.2 to 2.0; the dielectric tangent of the aforementioned resin substrate at 10 GHz is 0.0001 to 0.0020, and the ratio of its dielectric tangent at 40 GHz to that at 10 GHz is 0.8 to 1.2, and the frequency dependence of the dielectric tangent from 10 GHz to 40 GHz shows a negative correlation between the aforementioned organic resin and a positive correlation between the aforementioned quartz glass cloth.

2. The resin substrate as described in claim 1, wherein, It further comprises: silicon dioxide powder with a dielectric tangent of 0.0001 to 0.0015 at 10 GHz.

3. The resin substrate as described in claim 1 or 2, wherein, The aforementioned organic resin is one or more thermosetting resins selected from the group consisting of epoxy resin, allylated epoxy resin, maleimide resin, bismaleimide resin, cyanate ester resin, and cyclopentadiene-styrene copolymer resin.

4. The resin substrate as described in claim 3, wherein, The aforementioned thermosetting resin is a bismaleimide resin represented by the following general formula: In the aforementioned formula, A independently represents a tetravalent organic group containing an aromatic ring or an aliphatic ring, B is a divalent alkyl chain with 6 to 18 carbon atoms having an aliphatic ring that may contain heteroatoms, Q independently represents a straight-chain alkyl chain with 6 or more carbon atoms, R independently represents a straight-chain or branched alkyl chain with 6 or more carbon atoms, n represents a number from 1 to 10, and m represents a number from 0 to 10.

5. The resin substrate as described in claim 1 or 2, wherein, The aforementioned organic resin is one or more thermoplastic resins selected from the group consisting of polyphenylene ether, polyether ether ketone, polyether ketone, polyether ether, and fluororesin.

6. The resin substrate as described in claim 5, wherein, The aforementioned thermoplastic resin is a fluoropolymer.

7. The resin substrate as described in claim 6, wherein, The aforementioned fluororesin is selected from one or more of the group consisting of polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA).