Resin composition, coating solution, resin film, metal-clad laminate, circuit board, electronic device, and electronic apparatus

Abstract

This resin composition comprises: a first resin having a dielectric loss tangent of 0.0002-0.0020 at 10 GHz; and a second resin having a dielectric loss tangent of 0.0010-0.0040 at 10 GHz and a linear expansion coefficient of 1.0-40.0 ppm / K, wherein the second resin constitutes a continuous phase.

Description

Resin composition, coating liquid, resin film, metal-clad laminate, circuit board, electronic device and electronic equipment

[0001] The present invention relates to a resin composition, a coating liquid, a resin film, a metal-clad laminate, and a circuit board, an electronic device, and an electronic device using these resin compositions, which are useful as materials for circuit boards, etc. This application claims priority based on Japanese Patent Application No. 2023-169697 filed in Japan on September 29, 2023, and Japanese Patent Application No. 2023-169698 filed in Japan on September 29, 2023, the contents of which are incorporated herein by reference.

[0002] Polyimide is a resin with excellent heat resistance, mechanical properties, and electrical properties. Resin films using this polyimide are increasingly being used for applications such as insulating layers of circuit boards, such as flexible printed circuits (FPCs). In recent years, efforts have been made to increase transmission frequencies in information processing and communications to transmit and process large amounts of information, and circuit boards are being required to reduce transmission loss by improving the dielectric properties of their insulating layers. It is expected that in the future, the insulating layers that make up FPCs will be increasingly required to accommodate higher frequencies.

[0003] In order to reduce transmission loss in the high frequency band, Patent Document 1 proposes a polyimide film containing a structural unit (A1) derived from an ester bond-containing tetracarboxylic acid anhydride, a structural unit (A2) derived from a biphenyl skeleton-containing tetracarboxylic acid anhydride, and a structural unit (B1) derived from a biphenyl skeleton-containing diamine.

[0004] As seen in Patent Document 1, the basic properties of polyimides, such as thermoplasticity and non-thermoplasticity, as well as their mechanical and electrical properties, vary significantly depending on their structural units. Non-thermoplastic polyimides generally contain a large number of structural units with rigid chemical structures and are characterized by a high modulus of elasticity, a low coefficient of thermal expansion (CTE), and a high glass transition temperature (Tg). These properties are useful for ensuring the heat resistance and dimensional stability of circuit boards. However, it is difficult to achieve a low dielectric loss tangent (e.g., 0.0030 or less at 10 GHz) required for fifth-generation mobile communication systems (5G) and beyond. On the other hand, polyimides containing a large number of structural units containing aliphatic chains or alicyclic skeletons (hereinafter sometimes referred to as "aliphatic polyimides") are thermoplastic, have excellent adhesive properties, are soluble in solvents, and can achieve a low dielectric loss tangent due to the low polarity structure derived from the structural units containing aliphatic chains or alicyclic skeletons. However, it is difficult to reduce the CTE of aliphatic polyimides. Therefore, it has been difficult for non-thermoplastic polyimides or aliphatic polyimides to achieve both a low dielectric loss tangent and a low CTE by themselves.

[0005] Polymer alloys are known as a technology that can impart new functions to polymeric materials. Polymer alloys are polymeric materials that have new properties due to the mixing or chemical bonding of multiple polymers, and include polymer blends (non-reactive and reactive systems) and block copolymers. Polymer alloys are considered effective for i) improving the defects and properties of polymeric materials made from a single polymer, and ii) creating polymeric materials with completely new properties that have never been seen before (Non-Patent Document 1).

[0006] As a conventional technique related to polymer alloys, for example, Patent Document 2 proposes a composition containing a thermoplastic polyimide and a polystyrene elastomer (thermoplastic). However, films formed from the composition of Patent Document 2 tend to have a low dielectric loss tangent but a high coefficient of thermal expansion (CTE). Furthermore, Patent Document 3 proposes a composition containing a polyimide and an amorphous resin. However, films formed from the composition of Patent Document 3 have a low CTE but a high dielectric loss tangent.

[0007] Japanese Patent No. 7183377 Japanese Patent Application Laid-Open No. 2022-99778 International Publication WO2023 / 105969

[0008] Edited by the Society of Polymer Science, Basic Polymer Science, Tokyo Kagaku Dojin, 2nd edition (2020) RFFedors: Polym. Eng. Sci., 14 [2], 147-154 (1974)

[0009] As mentioned above, attempts have been made to improve resin properties by polymer alloy technology. However, when alloying two or more polymers (e.g., polyimides) with different structures and properties, it is difficult to prepare a uniform mixture due to differences in solubility in solvents, and the phase structure after alloying is unknown, making it difficult to control the phase structure to express properties. For these reasons, it is not necessarily easy to create a resin composition that can stably express desired properties.

[0010] Therefore, an object of the present invention is to provide a resin composition that combines a low CTE and a low dielectric loss tangent, using polymer alloy technology, and a coating liquid, a resin film, a metal-clad laminate, a circuit board, an electronic device, and an electronic apparatus that use the resin composition.

[0011] <1> A resin composition according to a first aspect of the present invention comprises a first resin having a dielectric loss tangent at 10 GHz of 0.0002 to 0.0020, and a second resin having a dielectric loss tangent at 10 GHz of 0.0010 to 0.0040 and a linear expansion coefficient of 1.0 to 40.0 ppm / K, wherein the second resin constitutes a continuous phase. <2> A resin composition according to a second aspect of the present invention is the resin composition according to the first aspect, wherein the weight average molecular weight of the first resin is 120,000 or less. <3> A resin composition according to a third aspect of the present invention has an SP value of 24.6 to 33.3 (J / cm 3 ) 1 / 2 and a component (A1) having an SP value of 15.0 to 24.5 (J / cm 3 ) 1 / 2and a component (B1) represented by the formula: wherein the component (A1) is a non-thermoplastic polyimide precursor, and the component (B1) is a soluble compound having a structural unit containing at least one of an aliphatic chain and an alicyclic skeleton, and the soluble compound is at least one of a soluble polyimide and a soluble polyimide precursor. <4> Aspect 4 of the present invention is the resin composition of Aspect 3, wherein the weight ratio (B1 / A1) of the component (B1) to the component (A1) is within the range of 15 / 85 to 83 / 17. <5> Aspect 5 of the present invention is a coating liquid comprising the resin composition of any one of Aspects 1 to 4 and a coating liquid having an SP value of 10.3 to 19.5 (J / cm 3 ) 1 / 2 and an organic solvent with an SP value of 19.7 to 30.8 (J / cm 3 ) 1 / 2 <6> A resin film according to aspect 6 of the present invention is a resin film comprising a single or multiple polyimide layers, wherein at least one of the polyimide layers has an SP value of 24.6 to 33.3 (J / cm 3 ) 1 / 2 and a component (A2) having an SP value of 15.0 to 24.5 (J / cm 3 ) 1 / 2and a component (B2) which is represented by the formula: wherein the component (A2) is a non-thermoplastic polyimide, and the component (B2) is a soluble polyimide having a structural unit containing an aliphatic chain or an alicyclic skeleton. <7> A resin film of Aspect 7 of the present invention includes a resin layer made of the resin composition of Aspect 1 or 2. <8> Aspect 8 of the present invention is the resin film of Aspect 6 or 7, wherein the dielectric dissipation factor at 10 GHz is 0.0030 or less when measured with a split post dielectric resonator (SPDR) in an environment of a temperature of 24 to 26°C and a relative humidity of 45 to 55%. <9> Aspect 9 of the present invention is the resin film of Aspect 8, wherein the dielectric dissipation factor at 10 GHz is 0.0025 or less. <10> A metal-clad laminate of Aspect 10 of the present invention is a metal-clad laminate comprising an insulating resin layer consisting of a single layer or multiple layers and metal layers laminated on one or both sides of the insulating resin layer, at least one of the insulating resin layers being composed of the resin film of any one of Aspects 6 to 9. <11> A circuit board of Aspect 11 of the present invention is a circuit board comprising an insulating resin layer consisting of a single layer or multiple layers and a conductor circuit layer laminated on one or both sides of the insulating resin layer, at least one of the insulating resin layers being composed of the resin film of any one of Aspects 6 to 9. <12> An electronic device of Aspect 12 of the present invention comprises the circuit board of Aspect 11. <13> An electronic device of Aspect 13 of the present invention comprises the circuit board of Aspect 11.

[0012] The resin composition and the coating liquid containing the resin composition according to each of the above embodiments contain two resins having predetermined properties, and thus can form a resin film that can stably exhibit both a low CTE and a low dielectric loss tangent. Therefore, the resin composition and the resin film according to each of the above embodiments can be particularly preferably used as a circuit board material for FPCs and the like in electronic devices and electronic equipment that require high-speed signal transmission.

[0013] Hereinafter, a resin composition, a coating liquid, a resin film, a metal-clad laminate, a circuit board, an electronic device, and an electronic apparatus according to embodiments of the present invention will be described.

[0014] [First Embodiment] <Resin Composition> A resin composition according to a first embodiment of the present invention comprises a first resin having a dielectric loss tangent at 10 GHz of 0.0002 to 0.0020, and a second resin having a dielectric loss tangent at 10 GHz of 0.0010 to 0.0040 and a linear expansion coefficient of 1.0 to 40.0 ppm / K, wherein the first resin has a smaller dielectric loss tangent than the second resin, and the second resin forms a continuous phase. Each element will be described below.

[0015] (First Resin) The dielectric loss tangent (Df) of the first resin at 10 GHz is 0.0002 to 0.0020. The dielectric loss tangent of the first resin at 10 GHz is preferably 0.0016 or less. It is more preferable that the dielectric loss tangent of the first resin is 0.0014 or less. By making the value of the dielectric loss tangent of the first resin lower than the dielectric loss tangent of the second resin, the dielectric loss tangent of the resin composition according to this embodiment can be reduced.

[0016] The dielectric constant (Dk) of the first resin at 10 GHz is preferably 3.5 or less. The dielectric constant of the first resin at 10 GHz is more preferably 3.0 or less. The dielectric constant of the first resin at 10 GHz is even more preferably 2.6 or less. If this dielectric constant exceeds 3.5, the dielectric constant of the resin composition according to the first embodiment may become high. The dielectric constant of the first resin may be 0.1 or more.

[0017] (CTE) The coefficient of linear expansion (CTE) of the first resin is not particularly limited. When the coefficient of linear expansion of the second resin is within a predetermined range and the second resin constitutes a continuous phase, the coefficient of linear expansion of the resin composition can be, for example, 50.0 ppm / K or less even if the coefficient of linear expansion of the first resin is 100.0 ppm / K or more. For example, the coefficient of linear expansion (CTE) of the first resin may be 50.0 to 1000.0 ppm / K.

[0018] The dielectric constant and dielectric loss tangent can be evaluated by the following method. The resin composition is molded into a film. The molding method is not particularly limited. For example, a resin film for evaluation may be obtained by dissolving the resin composition in a solvent, preparing a coating liquid, applying it to a support substrate, and drying it. Next, the dielectric constant (Dk) and dielectric loss tangent (Df) of the resin film at a predetermined frequency (e.g., 10 GHz) are measured using a vector network analyzer (e.g., Agilent, product name: E8363C) and a split post dielectric resonator (SPDR resonator). The dielectric constant and dielectric loss tangent are measured after leaving the film used for measurement for 24 hours under conditions of a temperature of 24 to 26°C and a relative humidity of 45 to 55%.

[0019] The SP value of the first resin is 15.0 to 24.5 (J / cm 3 ) 1 / 2 When the SP value of the first resin and the SP value of the second resin are within predetermined conditions, when the first resin and the second resin are mixed, the coefficient of linear expansion (CTE) can be easily reduced while the second resin becomes a continuous phase. The SP value of the first resin is 23.5 (J / cm 3 ) 1 / 2 The SP value of the first resin is preferably 18.0 (J / cm 3 ) 1 / 2 It is preferable that this is equal to or greater than this.

[0020] The SP value (solubility parameter) of a resin such as the first resin can be calculated based on the Fedors method described in Non-Patent Document 2. The SP value δ according to the Fedors method is calculated from the following formula (1): In the following formula (1), E is the cohesive energy (J / mol), V is the molar volume (cm 3 / mol). The SP value can be determined by calculating the cohesive energy and molecular volume for each structure constituting the resin, and then raising the sum of the cohesive energies of each component to the sum of the molecular volumes to the power of 1 / 2. For example, when the first resin is a polyimide or polyamic acid, it is preferable to take the acid-amine ratio into account and calculate the SP value for the imide structure and amic acid structure. δ = (E / V) １／２ ...(1)

[0021] The melting point of the first resin is preferably less than 260° C. The melting point of the first resin is preferably 240° C. or less, and more preferably within the range of 80 to 230° C. If the melting point of the first resin is less than 260° C., stress is alleviated between the first resin and the second resin, and the toughness of the molded product (such as a film) can be improved.

[0022] The melting point of the resin can be measured, for example, by a method in accordance with JIS K7121:2012.

[0023] The glass transition temperature of the first resin is preferably less than 180° C. The glass transition temperature of the first resin is preferably 160° C. or less, and more preferably in the range of 25 to 140° C. If the glass transition temperature of the first resin is less than 180° C., stress is alleviated between the first resin and the second resin, and the toughness of the molded product (such as a film) can be improved.

[0024] The storage modulus of the first resin at 180°C is 1.0 × 10 ７ Pa, and preferably 100 to 8.0 × 10 ６ The storage modulus of the first resin at 180°C is more preferably in the range of 1.0 × 10 ７ When the modulus is less than Pa, stress is alleviated between the first resin and the second resin, and the toughness of the molded product (film, etc.) can be improved.

[0025] The storage modulus and glass transition temperature of a resin can be measured by the following method. A film or resin sheet is cut into a size of 5 mm wide x 70 mm long to prepare an evaluation sample. Next, using a dynamic viscoelasticity apparatus (e.g., DMA: manufactured by TA Instruments, product name: RSA-G2), the sample is heated stepwise from 30°C to 500°C at a heating rate of 4°C / min, and measurement is performed at a frequency of 1 Hz. The temperature at the peak of tan δ is taken as the glass transition temperature Tg. Note that if multiple tan δ peaks appear, the highest temperature among the multiple peak temperatures is taken as Tg. Here, tan δ refers to the loss coefficient, and means the ratio (G'' / G') of the loss modulus G'' to the storage modulus G'.

[0026] The weight average molecular weight of the first resin is preferably 120,000 or less. The weight average molecular weight of the first resin is preferably 90,000 or less. It is even more preferable that the weight average molecular weight of the first resin is 60,000 or less. When the weight average molecular weight of the first resin is small, the phase separation state of the resin composition changes, and it is more likely to become a uniform phase. The weight average molecular weight of the first resin is preferably 5,000 or more. It is even more preferable that the weight average molecular weight of the first resin is 10,000 or more.

[0027] The number average molecular weight of the first resin is preferably 100,000 or less. The number average molecular weight of the first resin is preferably 60,000 or less. The number average molecular weight of the first resin is more preferably 35,000 or less. If the number average molecular weight of the first resin is small, the phase separation state of the resin composition changes, and it is more likely to become a uniform phase. The number average molecular weight of the first resin is preferably 5,000 or more.

[0028] "Measurement of weight average molecular weight (Mw) and number average molecular weight (Mn)" The weight average molecular weight and number average molecular weight are measured by a gel permeation chromatograph (for example, HLC-8420GPC manufactured by Tosoh Corporation). Polystyrene is used as a standard substance, and the developing solvent can be appropriately selected depending on the solubility of the resin. Examples of solvents that can be used include tetrahydrofuran (THF) and N,N-dimethylacetamide (DMAc).

[0029] Examples of the first resin include resins having a structural unit containing an aliphatic chain or alicyclic skeleton, such as polyimide, polyamide, maleimide, polyolefin (polyethylene, polypropylene, etc.), polyester, polyurethane, polystyrene, polystyrene elastomer, cycloolefin polymer (COP), polymethylpentene (PMP), copolymers of the above polymers, and cycloolefin copolymer (COC). By having a structural unit containing an aliphatic chain or alicyclic skeleton in the main chain of the first resin, the first resin is likely to have a low dielectric tangent, a low glass transition temperature, and be easily softened at high temperatures. Therefore, when blended with the second resin, stress is relaxed at the interface, preventing embrittlement of the molded product. Furthermore, the dielectric tangent of the resin composition according to the embodiment is likely to be reduced by the action during molding.

[0030] "Elongation" The elongation of the first resin is preferably 100% or more, more preferably 100% or more and 500% or less, and even more preferably 200% or more and 340% or less. If the elongation is less than 100%, the elongation of the resin film will not improve, leading to a deterioration in toughness.

[0031] The tensile modulus and elongation of a resin can be measured by the following method. For example, a Strograph R-1 (manufactured by Toyo Seiki Seisakusho, Ltd.) is used to perform a tensile test on a resin film having a width of 12.7 mm and a length of 127 mm at a temperature of 23°C and a relative humidity of 50% RH at a rate of 50 mm / min. The tensile modulus and elongation of the resin film can be calculated from the obtained results.

[0032] (Second Resin) The dielectric dissipation factor of the second resin at 10 GHz is 0.0010 to 0.0040. The dielectric dissipation factor of the second resin at 10 GHz is preferably 0.0020 or more. The dielectric dissipation factor of the second resin at 10 GHz is preferably 0.0035 or less. By having the dielectric dissipation factor of the second resin at 10 GHz be 0.0010 to 0.0040, it is possible to suppress an increase in the dielectric dissipation factor due to mixing of the second resin. The dielectric dissipation factor can be measured by the method described above.

[0033] The second resin has a coefficient of linear expansion (CTE) of 1.0 to 40.0 ppm / K. The coefficient of linear expansion of the second resin is preferably 30.0 ppm / K or less. The coefficient of linear expansion of the second resin is preferably 25.0 ppm / K or less. When the coefficient of linear expansion of the second resin is 10.0 to 40.0 ppm / K, expansion of the first resin can be suppressed when the second resin constitutes a continuous phase, and the coefficient of linear expansion of the resin composition can be 50.0 ppm / K or less.

[0034] "Measurement of Linear Expansion Coefficient" The linear expansion coefficient of a resin can be measured by the following method: Using a thermomechanical analyzer (for example, Hitachi High-Technologies Corporation (formerly Seiko Instruments Inc.), product name: TMA / 7100), a sample (width 3 mm x length 20 mm) is heated from 30°C to 180°C at a constant heating rate while applying a load of 5.0 g, and then held at that temperature for 10 minutes, followed by cooling at a rate of 5°C / min, to determine the average thermal expansion coefficient (linear expansion coefficient) from 180°C to 100°C.

[0035] The SP value of the second resin is 24.6 to 33.3 (J / cm 3 ) 1 / 2 When the SP value of the first resin and the SP value of the second resin satisfy a predetermined relationship, a resin mixture that has both a low coefficient of linear expansion (CTE) and a low dielectric loss tangent is easily achieved. The SP value of the second resin can be calculated based on the Fedors method, just like the SP value of the first resin. The SP value of the second resin is 31.0 (J / cm 3 ) 1 / 2 The SP value of the second resin is preferably 27.0 (J / cm 3 ) 1 / 2 It is preferable that this is equal to or greater than this.

[0036] The glass transition temperature of the second resin is preferably 180° C. or higher. The glass transition temperature is preferably within the range of 190 to 450° C., and more preferably within the range of 200 to 400° C. The glass transition temperature of the second resin can be evaluated by the method described above.

[0037] The melting point of the second resin is preferably 260° C. or higher. The melting point is preferably within the range of 280 to 500° C., and more preferably within the range of 300 to 450° C. The melting point of the second resin can be evaluated by the method described above.

[0038] The storage modulus of the second resin at 180°C is 1.0 × 10 ７ The storage modulus at 180°C is preferably 10 x 10 ７ Pa or more is preferable, and 100×10 ７ The storage modulus of the second resin at 180°C is 1.0 × 10 Pa or more. ７The heat resistance of the resin composition according to the first embodiment is improved by the storage modulus being equal to or higher than Pa. The storage modulus of the second resin can be measured by the method described above.

[0039] "Elongation" The elongation of the second resin is preferably 1.5% or more, more preferably 2.0% or more and 150% or less, and even more preferably 2.0% or more and 90% or less. If the elongation is less than 1.5%, the elongation of the resin film will not improve, leading to a deterioration in toughness.

[0040] The weight average molecular weight of the second resin is, for example, preferably in the range of 5,000 to 300,000, more preferably in the range of 10,000 to 200,000, and most preferably in the range of 15,000 to 150,000.

[0041] The number average molecular weight of the second resin is preferably 200,000 or less. The number average molecular weight of the second resin is preferably 60,000 or less. The number average molecular weight of the second resin is more preferably 35,000 or less. The number average molecular weight of the second resin may be 5,000 or more. The weight average molecular weight and number average molecular weight of the second resin can be measured by the above-mentioned methods.

[0042] Examples of the second resin include wholly aromatic polyimide (PI), non-thermoplastic polyimide, liquid crystal polymer (LCP), polyphenylene ether (PPE), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), syndiotactic polystyrene (SPS), polyamide, polyamideimide, polyethersulfone (PES), polysulfone (PS), polybenzimidazole (PBI), polybenzoxazole (PBO), polyarylate (PAR), and copolymers of the above polymers.

[0043] "Composition ratio" The weight ratio of the first resin to the second resin (first resin / second resin) in the resin composition according to the first embodiment is preferably in the range of 15 / 85 to 83 / 17, more preferably in the range of 25 / 75 to 75 / 25. From the viewpoint of suppressing embrittlement of the molded product, it is further preferably in the range of 30 / 70 to 70 / 30, and particularly preferably in the range of 40 / 60 to 70 / 30.

[0044] "Difference in SP Value" The difference between the SP value of the first resin and the SP value of the second resin is 3.0 (J / cm ３ ) １／２ It is preferable that the viscosity is 5.0 (J / cm ３ ) １／２ The difference between the SP value of the first resin and the SP value of the second resin is preferably 6.0 (J / cm ３ ) １／２ The difference between the SP value of the first resin and the SP value of the second resin is preferably 3.0 (J / cm ３ ) １／２ As a result, the second resin becomes a continuous phase, and the dielectric loss tangent of the resin composition according to the first embodiment can be reduced, while the linear expansion coefficient can be lowered.

[0045] The total amount of the first resin and the second resin in the resin composition according to the first embodiment may be more than 20% by weight, preferably 40% by weight or more, more preferably 50 to 100% by weight, and most preferably 80 to 100% by weight, based on the total mass of the resin composition. Here, the resin composition does not contain a solvent.

[0046] Dielectric loss tangent Df of the second resin at 10 GHz ２ and the dielectric loss tangent Df of the first resin at 10 GHz １ The difference between ２ -Df １ ) is preferably 0.0010 or more. ２ -Df １ ) is more preferably 0.0015 or more. ２ -Df １ It is more preferable that the difference (Df) is 0.0020 or more. ２ -Df １ It is particularly preferable that the difference (Df ２ -Df １ ) is not particularly limited, but the upper limit of the difference (Df ２ -Df １ ) may be 0.0040 or less. ２ -Df １) is 0.0010 or more, the dielectric loss tangent of the resin composition can be further reduced.

[0047] In the resin composition according to the first embodiment, the second resin constitutes a continuous phase. Here, the term "the second resin constitutes a continuous phase" means that the regions in which the second resin is present are continuously connected throughout the entire resin composition. In the resin composition according to the first embodiment, the phase structure of the resin composition is not particularly limited as long as the second resin constitutes a continuous phase. The resin composition may be a homogeneous phase (homogeneous miscible structure) in which the first resin and the second resin are miscible, or a phase-separated structure such as a sea-island structure or an interconnected structure. The second resin being a continuous phase allows the low linear expansion coefficient inherent to the second resin to be exhibited. Here, if there are no regions with a diameter of 500 nm or more in a 5 μm × 5 μm area measured using a scanning electron microscope, the structure is determined to be a homogeneous miscible structure. If there are regions with a circle equivalent diameter of 500 nm or more (e.g., island phases), the structure is determined to be a phase-separated structure. Here, the sea-island structure refers to a structure in which one continuous phase (sea phase) is discontinuously mixed with another phase (island phase). When the phase structure of the resin composition according to the first embodiment is a sea-island structure, the second resin constitutes the sea phase. The interconnected structure refers to a structure in which multiple components are mixed together while forming a continuous phase. In the case of an interconnected structure, it is sufficient that one of the continuous phases is constituted by the second resin.

[0048] When the phase-separated structure of the resin composition according to the first embodiment is an island-sea structure, the island phases preferably consist of the first resin. The average equivalent circle diameter of the island phases is preferably 0.001 μm to 20 μm. The average equivalent circle diameter of the island phases is more preferably 0.010 μm to 10 μm. By setting the average equivalent circle diameter of the island phases to 0.001 μm to 20 μm, the linear expansion coefficient can be further reduced. The equivalent circle diameter of the island phases means the diameter of a circle having an area equal to the area of ​​the island phases.

[0049] When the phase separation structure of the resin composition according to the first embodiment is a sea-island structure, the number density of island phases having a circle equivalent diameter of 500 nm or more is 0.01 to 0.300 pieces / μm ２ The number density is preferably 0.01 to 0.200 particles / μm ２ Therefore, the linear expansion coefficient can be further reduced.

[0050] When the phase structure of the resin composition according to the first embodiment is a homogeneous compatible structure, island phases may be present in some parts. In this case, the number density of island phases having a circle equivalent diameter of 500 nm or more is 0.01 pieces / μm ２ It is preferable that the number density is less than 0.01 particles / μm. ２ When the phase structure of the resin composition according to the first embodiment is a homogeneous compatible structure, there is basically no island phase, so the lower limit of the number density is 0.

[0051] "Confirmation of the continuous phase, measurement of the average circle-equivalent diameter and number density of the island phases" The continuous phase can be confirmed and the average circle-equivalent diameter and number density of the island phases can be measured using the following method. The resin film is cut and embedded in epoxy resin, and then a cross section of the film is exposed using a cross section polisher (CP). Osmium is vapor-deposited on the obtained cross section, and a sample of approximately 7 mm is prepared for cross-sectional observation.

[0052] The cross-section of the above-mentioned sample for cross-section observation is observed in the thickness direction using a scanning electron microscope (SEM, for example, manufactured by JEOL Ltd., product name: JSM-IT500HR) at an acceleration voltage of 10 kV, an irradiation current of 80 μA, and a magnification of 3000x. When determining by SEM observation, for example, the dark colored portion is regarded as the first resin, and the light colored portion is regarded as the second resin. The ratio of each resin is preferably confirmed using microscopic Raman analysis or an energy dispersive electron X-ray spectrometer (EDX). Image analysis is performed using various analysis software (for example, Image Pro 10), and based on the above definitions, the continuous phase is confirmed, and the average circle-equivalent diameter of the island phases and the number density of island phases 500 nm or larger per unit area are calculated (calculating the number of islands 500 nm or larger per unit area). Specifically, three SEM images obtained by observing the phase-separated structure are analyzed using analysis software (Image Pro 10), and the averages are used as the evaluation values ​​(average circle-equivalent diameter of island phases, number density of island phases 500 nm or larger per unit area). The analysis conditions can be changed appropriately depending on the sample, but the analysis process can also be performed after removing noise using, for example, spatial calibration or a median filter.

[0053] The determination of the region where the second resin is present is performed as follows. When the phase structure of the resin composition according to the first embodiment is a phase-separated structure such as a sea-island structure, the proportion of resin constituting each phase (e.g., sea phase, island phase) is examined using a Raman microscope or the like. The phase (region) where the proportion of the second resin is higher than the proportion of the first resin is determined to be the region where the second resin is present.

[0054] In the SEM image obtained by the above observation, if the region where the second resin is present is continuously connected from one end of the image to the other end, it is determined that the second resin constitutes a continuous phase.

[0055] When the phase structure of the resin composition according to the first embodiment is a homogeneous compatible structure, if the presence of the second resin can be confirmed by Raman microscopy or the like, the entire homogeneous phase is determined to be the region where the second resin is present. In this case, the second resin is determined to constitute a continuous phase.

[0056] "Optional Components" The resin composition according to the first embodiment may further contain optional components such as inorganic fillers, organic fillers, plasticizers, curing accelerators, coupling agents, pigments, and flame retardants, as needed, within the scope of the invention. Examples of inorganic fillers include silicon dioxide, aluminum oxide, beryllium oxide, niobium oxide, titanium oxide, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, magnesium fluoride, potassium silicofluoride, and metal phosphinates. These may be used alone or in combination of two or more. Furthermore, as optional components, resin components other than the first resin and the second resin may be added within the scope of the invention.

[0057] <Coating Liquid> The coating liquid according to the first embodiment contains the resin composition according to the first embodiment and an organic solvent capable of dissolving the resin composition. The coating liquid according to the first embodiment can be prepared as a resin solution (varnish) containing a solvent. In the present invention, the term "solvent" includes organic solvents and is used in a broader sense than organic solvents. As the organic solvent, an organic solvent appropriate for each of the first resin and the second resin can be appropriately selected and used, and the following solvent combinations can be exemplified as preferred organic solvents.

[0058] First solvent: Solubility parameter (SP) of 5 to 9.5 (cal / cm ３ ) １／２ (10.3 to 19.5 (J / cm ３ ) １／２ The first solvent is a low polarity solvent, and by using this, it becomes easy to prepare a varnish using the first resin. It is preferable that the first resin is easily soluble in the first solvent. As the first organic solvent, for example, toluene (SP value 8.9 (cal / cm) ３ ) １／２ , 18.2 (J / cm ３ ) １／２ ), xylene (SP value 8.8 (cal / cm ３ ) １／２ , 18.0 (J / cm ３ ) １／２ ), tetrahydrofuran (THF; SP value 9.1 (cal / cm ３ ) １／２ , 18.6 (J / cm ３ ) １／２ ), hexane (SP value 7.3 (cal / cm ３ ) １／２ , 15.0 (J / cm ３ ) １／２ ), diethyl ketone (SP value 8.8 (cal / cm ３ ) １／２ , 18.0 (J / cm ３ ) １／２ ), butyl acetate (SP value 8.5 (cal / cm ３ ) １／２ , 17.4 (J / cm ３ ) １／２ ), diethyl carbonate (SP value 8.8 (cal / cm３ ) １／２ , (18.0J / cm ３ ) １／２ ), etc. These may be used in combination of two or more. The SP value of a solvent means the Hildebrand solubility parameter.

[0059] Second solvent (component (D)): SP value (solubility parameter) of 9.6 to 15 (cal / cm ３ ) １／２ (19.7~30.8 (J / cm ３ ) １／２ The second solvent is a highly polar solvent, and by using this, it becomes easy to prepare a varnish using the second resin. It is preferable that the second resin is easily soluble in the second solvent. As the organic solvent, for example, N,N-dimethylacetamide (DMAc; SP value 10.8 (cal / cm ３ ) １／２ , 22.1 (J / cm ３ ) １／２ ), N,N-dimethylformamide (DMF; SP value 12.1 (cal / cm ３ ) １／２ , 24.8 (J / cm ３ ) １／２ ), N-methyl-2-pyrrolidone (NMP; SP value 11.3 (cal / cm ３ ) １／２ , 23.1 (J / cm ３ ) １／２ ), cyclohexanone (SP value 9.9 (cal / cm ３ ) １／２ , 20.3 (J / cm ３ ) １／２ ), methanol (SP value 14.8 (cal / cm ３ ) １／２ , 30.3 (J / cm ３ ) １／２ ), acetonitrile (SP value 11.9 (cal / cm ３ ) １／２ , 24.3 (J / cm ３ ) １／２ ), gamma-butyrolactone (SP value 12.6 (cal / cm ３ ) １／２ , 25.8 (J / cm ３) １／２ ), dimethyl sulfoxide (SP value 14.5 (cal / cm ３ ) １／２ , 29.7 (J / cm ３ ) １／２ ), dimethyl carbonate (SP value 9.9 (cal / cm ３ ) １／２ , 20.3 (J / cm ３ ) １／２ These may be used in combination of two or more kinds.

[0060] The SP value of the first solvent (SP Ｃ ) and the SP value of the second solvent (SP Ｄ ) difference (SP Ｃ -SP Ｄ ) is 0.5 (cal / cm ３ ) １／２ ((1.0(J / cm ３ ) １／２ ) or more, and 1.0 (cal / cm ３ ) １／２ ((2.1(J / cm ３ ) １／２ ) or more is more preferable. Ｃ -SP Ｄ ) is 5.0 (cal / cm ３ ) １／２ ((10.3(J / cm ３ ) １／２ ) is preferably less than the difference (SP Ｃ -SP Ｄ ) is 0.5 (cal / cm ３ ) １／２ By satisfying the above, the first resin and the second resin can be easily mixed. When two or more types of the first solvent or the second solvent are used in combination, the SP value of the first solvent (SP Ｃ ) and the SP value of the second solvent (SP Ｄ ) is the difference (SP) between the average values ​​of two or more types. Ｃ -SP Ｄ ) can be calculated.

[0061] The volume ratio of the first solvent to the second solvent in the coating liquid (first solvent / second solvent) is preferably within a range of 5 / 95 to 95 / 5, more preferably within a range of 10 / 90 to 90 / 10, and even more preferably within a range of 25 / 75 to 75 / 25. Within the above range, it becomes easy to prepare a varnish by mixing components (A) and (B).

[0062] The total content of the solvent is not particularly limited, but it is preferable to adjust the concentration of the first resin and the second resin in the coating liquid so that the total concentration is about 5 to 30% by weight.

[0063] The viscosity of the coating liquid according to the first embodiment is not particularly limited, but is preferably in the range of 100 cP to 100,000 cP, more preferably 500 cP to 50,000 cP, to improve the handling properties when applying the coating liquid and facilitate the formation of a coating film of uniform thickness. The viscosity range described above can prevent defects such as uneven thickness and streaks from occurring in the film during the coating operation using a coater or the like.

[0064] The viscosity of the coating liquid can be measured by the following method: Using an E-type viscometer (manufactured by Brookfield, product name: DV-II+Pro), the viscosity of the coating liquid is measured at 25°C. The rotation speed is set so that the torque is 10% to 90%, and the viscosity is determined as the value when the viscosity stabilizes after 2 minutes have passed since the start of measurement.

[0065] The resin composition according to the first embodiment can be produced by mixing the first resin and the second resin. In this case, it is preferable to mix the components in the form of a resin solution dissolved in a solvent. For example, a resin solution of the first resin may be blended into a resin solution (varnish) of the second resin and mixed, or a resin solution of the first resin may be blended into a resin solution (varnish) of the second resin component and mixed. The resin composition according to the first embodiment can be obtained by removing the solvent from the coating liquid produced by mixing using a vacuum cleaner or the like. In other words, the solid content of the coating liquid according to the first embodiment is the resin composition according to the first embodiment. Here, the solid content refers to the remainder after removing the solvent from the coating liquid.

[0066] The resin composition according to the first embodiment can be used for applications such as materials for insulating layers in circuit boards such as flexible printed circuits (FPCs), rigid boards, rigid-flex boards, multilayer boards, build-up boards, and high-frequency boards, and as coating agents.

[0067] <Resin Film> The resin film according to the first embodiment is a resin film consisting of a single layer or multiple layers, at least one of which contains a first resin and a second resin. The resin film according to the first embodiment preferably includes a resin layer made of the resin composition according to the first embodiment. The resin film according to the first embodiment has excellent high-frequency characteristics because it has a layer made of the resin composition according to the first embodiment.

[0068] The method for producing the resin film according to the first embodiment is not particularly limited, and known methods can be used. For example, it is preferable to produce the film by repeatedly applying and drying the resin composition according to the first embodiment to a supporting substrate one or more times. The method for applying the resin composition according to the first embodiment to a supporting substrate is not particularly limited, and it can be applied using a coater such as a comma, die, knife, or lip. Note that by using a metal foil as the supporting substrate, the metal-clad laminate according to the first embodiment described below can be produced.

[0069] The resin film according to the first embodiment may be a film (sheet) made of only insulating resin, or may be an insulating resin film laminated on a substrate such as a resin sheet, such as copper foil, a glass plate, a polyimide film, a polyamide film, or a polyester film.

[0070] The resin film according to the first embodiment preferably has a thickness in the range of, for example, 5 to 150 μm, and more preferably in the range of, for example, 8 to 125 μm. If the thickness of the resin film according to the first embodiment is less than 5 μm, there is a risk of problems such as wrinkles occurring during transport during production of the resin film, or the resin film may not exhibit sufficient toughness, resulting in a failure to obtain a self-supporting film. On the other hand, if the thickness of the resin film exceeds 150 μm, there is a risk of a decrease in productivity of the resin film.

[0071] "Dielectric Constant" In order to ensure impedance matching when used in a circuit board such as an FPC and to reduce loss of electrical signals, the resin film according to the first embodiment preferably has a dielectric constant (Dk) at 10 GHz after 24 hours of conditioning under conditions of a temperature of 24 to 26°C and a relative humidity of 45 to 55% of 3.5 or less, more preferably 3.0 or less. If this dielectric constant exceeds 3.5, problems such as electrical signal loss are likely to occur in the transmission path of high-frequency signals when used in a circuit board such as an FPC. The dielectric constant can be measured by the method described above.

[0072] "Dielectric Loss Tangent" Furthermore, in order to reduce electrical signal loss when used in a circuit board such as an FPC, the resin film according to the first embodiment preferably has a dielectric loss tangent (Tan δ) at 10 GHz measured using a split post dielectric resonator (SPDR) after 24 hours of humidity conditioning under conditions of a temperature of 24 to 26°C and a relative humidity of 45 to 55% at 10 GHz. The dielectric loss tangent (Tan δ) is preferably 0.0040 or less, more preferably 0.0030 or less, and most preferably 0.0025 or less. If the dielectric loss tangent exceeds 0.0040, problems such as electrical signal loss are likely to occur in the transmission path of high-frequency signals when used in a circuit board such as an FPC. The dielectric loss tangent of the resin film according to the first embodiment can be measured using the method described above. The lower limit of the dielectric loss tangent of the resin film according to the first embodiment is not particularly limited and may be 0.0001.

[0073] "Glass transition temperature" When the resin film according to the first embodiment is amorphous and has no melting point, it preferably has a glass transition temperature (Tg) of 180°C or higher, more preferably in the range of 180 to 400°C. When the resin film has a Tg of 180°C or higher, it can achieve heat resistance that enables use in mounting and in high-temperature environments. The glass transition temperature can be measured by the method described above.

[0074] "Melting Point" When the resin film according to the first embodiment is crystalline and has a melting point, the melting point (Tm) is preferably 260°C or higher, and more preferably in the range of 260 to 450°C. When the resin film has a melting point Tm of 260°C or higher, it can achieve heat resistance that allows it to be used in mounting and in high-temperature environments. The melting point can be measured by the method described above. When multiple peaks appear in the measurement using a differential scanning calorimeter, the maximum temperature among the peak temperatures is taken as the melting point.

[0075] (CTE) The resin film according to the first embodiment preferably has a CTE of 50.0 ppm / K or less, more preferably in the range of 0 to 30.0 ppm / K. By having a CTE of 50.0 ppm / K or less, the dimensional change rate can be easily controlled when the resin film is made into a resin film or a metal-clad laminate. The CTE can be measured by the method described above.

[0076] "Storage Modulus" The resin film according to the first embodiment has a storage modulus of 1.0 × 10 at 180°C. ６ Pa or more, and ７ Pa or more, and more preferably 1.0 × 10 ７ ~1.0 x 10 １０ In addition, the resin film according to the first embodiment has a storage modulus at 260°C of 1.0 × 10 ５ Pa or more, and ６ Pa or more, and more preferably 1.0 × 10 ６ Pa ~ 5.0 x 10 ９It is most preferable that the storage modulus is in the range of Pa. By satisfying the storage modulus at each temperature above, heat resistance that enables use in mounting and in high-temperature environments can be achieved. The storage modulus can be measured by the method described above.

[0077] The phase structure of the resin film according to the first embodiment is the same as the phase structure of the resin composition according to the first embodiment.

[0078] <Metal-clad laminate> The metal-clad laminate according to the first embodiment comprises an insulating resin layer and a metal layer laminated on one or both surfaces of the insulating resin layer, and at least one insulating resin layer is made of the resin film. Note that the metal-clad laminate according to the first embodiment may also include any other layer.

[0079] The material of the metal layer is not particularly limited, but examples thereof include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof. Among these, copper or copper alloys are particularly preferred. The material of the wiring layer in the circuit board of this embodiment, which will be described later, is the same as that of the metal layer.

[0080] The thickness of the metal layer is not particularly limited, but when a metal foil such as copper foil is used, it is preferably 35 μm or less, and more preferably in the range of 5 to 25 μm. From the viewpoint of production stability and handling, the lower limit of the thickness of the metal foil is preferably 5 μm. When copper foil is used, it may be rolled copper foil or electrolytic copper foil. Furthermore, commercially available copper foil may be used as the copper foil.

[0081] The surface roughness of the metal layer is not particularly limited, but from the viewpoint of ensuring adhesion to the adhesive layer while reducing conductor loss, it is preferable that the metal layer has a roughened surface with a maximum height (Rz) in the range of 0.3 to 1.5 μm. Furthermore, the metal foil may be subjected to a surface treatment, for example, with siding, aluminum alcoholate, aluminum chelate, silane coupling agent, or the like, for the purpose of, for example, rust prevention or improving adhesive strength.

[0082] <Circuit Board> The circuit board according to the first embodiment is formed by wiring the metal layer of the metal-clad laminate. One or more metal layers of the metal-clad laminate are patterned by a conventional method to form a wiring layer (conductor circuit layer), thereby producing a circuit board such as an FPC. The circuit board may also include a coverlay film that covers the wiring layer.

[0083] <Electronic Device / Electronic Device> The electronic device and electronic device according to the first embodiment include the circuit board described above. Examples of the electronic device according to this embodiment include display devices such as liquid crystal displays, organic EL displays, and electronic paper, as well as organic EL lighting, solar cells, touch panels, camera modules, inverters, converters, and components thereof. Examples of the electronic device include hard disk drives (HDDs), DVDs, mobile phones, smartphones, tablet devices, automotive electronic control units (ECUs), and power control units (PCUs). Circuit boards are preferably used in these electronic devices and electronic devices as components such as wiring for moving parts, cables, and connectors.

[0084] The above describes the resin composition, coating liquid, resin film, metal-clad laminate, circuit board, electronic device, and electronic equipment according to the first embodiment. The resin composition according to the first embodiment includes a first resin having a dielectric loss tangent of 0.0002 to 0.0020 at 10 GHz and a second resin having a dielectric loss tangent of 0.0010 to 0.0040 at 10 GHz and a linear expansion coefficient of 1.0 to 40.0 ppm / K, with the second resin constituting a continuous phase. Therefore, the resin composition according to the first embodiment has both a low CTE and a low dielectric loss tangent.

[0085] In the first embodiment, the dielectric loss tangent of the first resin at 10 GHz has been described, but the present invention is not limited to the dielectric loss tangent of the first resin at 10 GHz. It is sufficient that the dielectric loss tangent of the first resin is 0.0002 to 0.0020 at the frequency used in the target product. Examples of frequencies include 28 GHz, 40 GHz, 60 GHz, and 110 GHz.

[0086] In the first embodiment, the dielectric loss tangent of the second resin at 10 GHz has been described, but the present invention is not limited to the dielectric loss tangent of the second resin at 10 GHz. It is sufficient that the dielectric loss tangent of the second resin has a value of 0.0010 to 0.0040 at the frequency used in the target product. Examples of frequencies include 28 GHz, 40 GHz, 60 GHz, and 110 GHz.

[0087] As long as the second resin in the resin composition of the first embodiment constitutes a continuous phase, the resin composition of the first embodiment may have a crosslinked structure between the first resin and the second resin. The crosslinked structure can be formed by adding a known crosslinking agent such as isocyanate.

[0088] Second Embodiment <Resin Composition> The resin composition according to the second embodiment has an SP value of 24.6 to 33.3 (J / cm 3 ) 1 / 2 and a component (A1) having an SP value of 15.0 to 24.5 (J / cm 3 ) 1 / 2 and a component (B1) represented by the formula: wherein the component (A1) is a non-thermoplastic polyimide precursor, and the component (B1) is a soluble compound having a structural unit containing at least one of an aliphatic chain and an alicyclic skeleton. The soluble compound of the component (B1) is at least one of a soluble polyimide and a soluble polyimide precursor. The resin composition according to the second embodiment may contain both a soluble polyimide and a soluble polyimide precursor.

[0089] Polyimide is obtained by reacting a tetracarboxylic acid anhydride component with a diamine component, and contains a tetracarboxylic acid anhydride residue derived from the tetracarboxylic acid anhydride component and a diamine residue derived from the diamine component. In this specification, the term "polyimide" refers to a polymer having an imide group in its molecular structure, such as polyamideimide, polyetherimide, polyesterimide, polysiloxaneimide, or polybenzimidazoleimide, in addition to polyimide.

[0090] (Component (A1)) Component (A1) is a polyimide precursor (polyamic acid) obtained by reacting a tetracarboxylic anhydride component with a diamine component, and the polyimide after imidization exhibits non-thermoplasticity. Note that, while the term "non-thermoplastic polyimide" generally refers to a polyimide that does not soften or exhibit adhesiveness even when heated, in this specification, it refers to a polyimide having a storage modulus of 1.0 × 10 at 30°C measured using a dynamic mechanical analyzer (DMA). ９ Pa or more, and the storage modulus in the temperature range within the glass transition temperature + 30°C is 1.0 × 10 ７ The term "thermoplastic polyimide" generally refers to a polyimide that can be softened by heating and solidified by cooling repeatedly, and whose glass transition temperature (Tg) can be clearly confirmed. In this specification, however, the term "thermoplastic polyimide" refers to a polyimide having a storage modulus of 1.0×10 Pa or more at 30° C. as measured using a dynamic mechanical analyzer (DMA). ９ Pa or more, and the storage modulus in the temperature range within the glass transition temperature + 30°C is 1.0 × 10 ７ This refers to polyimides that exhibit a modulus of less than Pa.

[0091] "Weight-Average Molecular Weight" The weight-average molecular weight of the non-thermoplastic polyimide precursor of component (A1) is preferably in the range of 5,000 to 300,000, more preferably 10,000 to 200,000, and most preferably 15,000 to 150,000. If the weight-average molecular weight of the non-thermoplastic polyimide precursor of component (A1) is less than 5,000, film properties are impaired and low CTE characteristics cannot be achieved. Furthermore, the dielectric loss tangent deteriorates due to an increase in terminal functional groups. On the other hand, if the weight-average molecular weight of the non-thermoplastic polyimide precursor of component (A1) exceeds 300,000, the viscosity increases excessively, making the film insoluble in solvents. The weight-average molecular weight of the non-thermoplastic polyimide of component (A2), described below, is the same as that of component (A1). It can be measured by the method described above.

[0092] "Glass transition temperature" The non-thermoplastic polyimide precursor of component (A1) preferably has a glass transition temperature (Tg) of 180°C or higher, more preferably in the range of 200 to 450°C, after imidization. If the Tg of the non-thermoplastic polyimide is less than 180°C, the Tg of the formed resin film will be less than 180°C, and heat resistance sufficient for use in packaging or in high-temperature environments will not be obtained. The glass transition temperature can be measured by the method described above.

[0093] The non-thermoplastic polyimide precursor of component (A1) has a viscosity of 24.6 to 33.3 (J / cm 3 ) 1 / 2 When the SP value of component (A1) and the SP value of component (B1) satisfy the predetermined relationship, a resin mixture that has both a low coefficient of linear expansion (CTE) and a low dielectric loss tangent is easily obtained. The SP value of component (A1) is 31.0 (J / cm 3 ) 1 / 2 The SP value of the component (A1) is preferably 27.0 (J / cm 3 ) 1 / 2 The SP value of the component (A1) (SP Ａ ) and the SP value of the component (B1) (SP Ｂ ) difference (SP Ａ -SP Ｂ ) is 1.5 (J / cm ３ ) １／２ More than 3.0 (J / cm ３ ) １／２ ) or more is more preferable, and 6.0 J / cm ３ ) １／２ ) or more. The SP value of the component (A1) can be calculated based on the Fedors method, similar to the SP value of the first resin according to the first embodiment.

[0094] "Coefficient of linear expansion (CTE)" The non-thermoplastic polyimide precursor of component (A1) preferably has a coefficient of linear expansion (CTE) of 40.0 ppm / K or less, more preferably in the range of 1.0 to 40.0 ppm / K, when the non-thermoplastic polyimide is formed into a film after imidization. If the CTE exceeds 40.0 ppm / K, dimensional stability will be impaired when applied to a resin film or metal-clad laminate. The CTE can be measured by the method described above.

[0095] "Elongation" When the non-thermoplastic polyimide precursor of component (A1) is formed into a film by itself after imidization, the elongation is preferably 1.5% or more, more preferably 2.0% or more and 150% or less. It is even more preferably 2.0% or more and 90% or less. If the elongation is less than 1.5%, the elongation of the resin film will not improve, leading to a deterioration in toughness. The elongation can be measured by the method described above.

[0096] As the component (A1), any non-thermoplastic polyimide precursor generally used as a material for circuit boards and the like can be used without any particular limitation. However, preferred non-thermoplastic polyimide precursors will be described below using examples of tetracarboxylic acid anhydrides and diamine compounds as raw materials.

[0097] The non-thermoplastic polyimide precursor of component (A1) contains a tetracarboxylic acid residue and a diamine residue. In this specification, the tetracarboxylic acid residue refers to a tetravalent group derived from a tetracarboxylic dianhydride, and the diamine residue refers to a divalent group derived from a diamine compound. The polyimide preferably contains an aromatic tetracarboxylic acid residue derived from an aromatic tetracarboxylic dianhydride and an aromatic diamine residue derived from an aromatic diamine.

[0098] "Tetracarboxylic acid residue" Any tetracarboxylic acid used in the non-thermoplastic polyimide precursor of component (A1) can be used without particular limitation. Examples of such acid anhydrides include pyromellitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2,3',3,4'-biphenyltetracarboxylic dianhydride, 4,4'-biphenol-bis(trimellitate anhydride), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 4,4'-oxydiphthalic anhydride, 2,2',3,3'-, 2,3,3',4'-, or 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,3',3,4 '-diphenyl ether tetracarboxylic acid dianhydride, bis(2,3-dicarboxyphenyl)ether dianhydride, 3,3'',4,4''-, 2,3,3'',4''- or 2,2'',3,3''-p-terphenyl tetracarboxylic acid dianhydride, 2,2-bis(2,3- or 3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)methane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3- or 3,4-dicarboxyphenyl) 2,3,6,7-anthracenetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride (NTCDA), 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride , 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic acid dianhydride, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride, 2,3,6,7- (or 1,4,5,8-) tetrachloronaphthalene-1,4,5,8- (or 2,3,6,7-) tetracarboxylic acid dianhydride, 2,3,8,9-, 3,4,9,10-, 4,5,10,11- or 5,6,11,12-perylene-tetracarboxylic acid dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4,4'-bis(2,3-dicarboxyphenoxy)diphenylmethane dianhydride, ethylene glycol bisanhydrotrimellitate, p-biphenylene bis(trimellitic acid monoester dihydrate) (BP-TME), 2,2',3,3',5,5'-hexamethyl[1,1'-biphenyl]-4,4'-diyl bis(1,3-dioxo-1,3-dihydro-2 -benzofuran-5-carboxylate) (TMPBP-TME), 2,6-naphthalenebis(trimellitic acid monoester anhydride) (26DHN-TME), 1,3-dihydro-1,3-dioxo-5,5'-(3,3'-dimethyl[1,1'-biphenyl]-4,4'-diyl)ester, 1,3-dihydro-1,3-dioxo-5,5'-(3,3',5,5'-tetramethyl[1,1'-biphenyl]-4,4'-diyl)ester, 1,4-phenylenebis(trimellitic acid monoester)dianhydride (TAHQ), and other aromatic tetracarboxylic acid dianhydrides are also usable. Among these, it is particularly preferable to use acid dianhydrides having an ester group in the molecule represented by the following general formula (1), which are expected to improve the linearity of polyimide molecular chains and achieve a low CTE due to in-plane orientation, or acid anhydrides having a biphenyl skeleton or a naphthalene skeleton, such as 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA) and 2,3,6,7-naphthalenetetracarboxylic dianhydride (NTCDA). These tetracarboxylic acid anhydrides can be used alone or in combination of two or more. In this specification, the tetracarboxylic acid dianhydride residue derived from the tetracarboxylic acid dianhydride represented by general formula (1) may be referred to as "acid dianhydride residue (1)."

[0099]

[0100] In general formula (1), Ar represents a divalent group containing one or more aromatic rings, and is preferably a divalent group selected from the following formulae:

[0101]

[0102] In the above formula, R1 represents an alkyl group having 1 to 3 carbon atoms, and m independently represents an integer of 0 to 4, but it is more preferable that the group has no substituent (m=0).

[0103] The compound represented by general formula (1) is an ester group-containing acid dianhydride, and despite its relatively large molecular weight, allows for a reduced imide group concentration, yet still maintains a low CTE. Furthermore, the ester structure has the effect of imparting an ordered structure to the entire polymer through intermolecular interactions. In particular, when the molecule contains a biphenyl or naphthalene skeleton and two ester structures (—CO—O—) bonded to the biphenyl or naphthalene skeleton, the rigidity of the biphenyl and naphthalene skeletons makes it easier to form an ordered structure, which is preferable. Therefore, the inclusion of the acid dianhydride residue (1) not only enables a reduction in CTE (lowering the CTE), but also contributes to a reduction in the dielectric loss tangent (lowering the dielectric loss tangent) by improving the ordered molecular structure and suppressing its movement.

[0104] Examples of the tetracarboxylic dianhydride represented by the general formula (1) include p-biphenylenebis(trimellitic acid monoester dihydrate) (BP-TME), 2,2',3,3',5,5'-hexamethyl[1,1'-biphenyl]-4,4'-diyl=bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylate) (TMPBP-TME), 2,6-naphthalenebis(trimellitic acid monoester Examples of suitable dianhydrides include 1,3-dihydro-1,3-dioxo-5,5'-(3,3'-dimethyl[1,1'-biphenyl]-4,4'-diyl)ester, 1,3-dihydro-1,3-dioxo-5,5'-(3,3',5,5'-tetramethyl[1,1'-biphenyl]-4,4'-diyl)ester, and 1,4-phenylenebis(trimellitic acid monoester)dianhydride (TAHQ). Among these, BP-TME and 26DHN-TME are particularly preferred due to their significant effect of lowering the CTE and dielectric loss tangent.

[0105] Furthermore, tetracarboxylic acid residues having a biphenyl or naphthalene skeleton have high planarity and linearity, which can promote in-plane orientation by improving the linearity of polyimide molecular chains, thereby improving CTE. Furthermore, they contribute to the stacking of molecular chains, which makes it easier to form an ordered structure, and suppress molecular motion, thereby improving the dielectric loss tangent.

[0106] The content of the acid dianhydride residue (1) in the non-thermoplastic polyimide precursor of component (A1) is preferably 20 mol % or more, more preferably 25 mol % or more, and most preferably in the range of 50 to 100 mol %, based on the total tetracarboxylic dianhydride residues. If the content of the acid dianhydride residue (1) is less than 20 mol %, the effects of improving the molecular order structure and suppressing molecular motion, thereby lowering the dielectric loss tangent and CTE, are not fully exhibited.

[0107] Furthermore, the same effect can be achieved by using a tetracarboxylic acid residue having a biphenyl skeleton or a naphthalene skeleton (excluding those that overlap with the acid dianhydride residue (1)) instead of the acid dianhydride residue (1) in the non-thermoplastic polyimide precursor of component (A1). The content of the tetracarboxylic acid residue is preferably 20 mol % or more, more preferably 25 mol % or more, and most preferably in the range of 50 to 100 mol %, based on the total tetracarboxylic acid dianhydride residues.

[0108] "Diamine Component" The non-thermoplastic polyimide precursor of component (A1) can be any diamine compound generally used in non-thermoplastic polyimide precursors, without limitation. Examples of such diamine compounds include 1,4-diaminobenzene (p-PDA; paraphenylenediamine), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-diethyl-4,4'-diaminobiphenyl (m-EB), 2,2'-diethoxy-4,4'-diaminobiphenyl (m-EOB), 2,2'-dipropoxy-4,4'-diaminobiphenyl (m-POB), 2,2'-di-n-propyl-4,4'-diaminobiphenyl (m-NPB), 2,2'-divinyl-4,4'-diaminobiphenyl (VAB), 4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl (TFMB), 4-aminophenyl-4'-aminobenzoate (APAB), 3,3'-diaminodiphenylmethane, 3,3'-diaminodiphenylpropane, 3,3'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl ether, 3,4'-diamino Diphenyl ether, 3,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylpropane, 3,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, (3,3'-bisamino)diphenylamine, 1,4-bis(3-aminophenoxy)benzene, 3-[4-(4-aminophenoxy)phenoxy]benzenamine, 3-[3-(4-aminophenoxy)phenoxy]benzenamine, 1,3-bis(4-aminophenoxy)benzene (TPE-R ), 1,3-bis(3-aminophenoxy)benzene (APB), 4,4'-[2-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[4-methyl-(1,3-phenylene)bisoxy]bisaniline, 4,4'-[5-methyl-(1,3-phenylene)bisoxy]bisaniline, bis[4,4'-(3-aminophenoxy)]benzanilide, 4-[3-[4-(4-aminophenoxy)phenoxy]phenoxy]aniline, 4,4'-[oxybis(3,1-phenyleneoxy)]bisaniline, bis[4-(4-aminophenoxy)phenyl]ether (BAPE), bis[4-(4-aminophenoxy)phenyl]sulfone (BAPS), bis[4-(4-aminophenoxy)phenyl]ketone (BAPK), 2,2-bis-[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(3-amino 2,2-bis-[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis-[4-(3-aminophenoxy)phenyl]hexafluoropropane, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 3,3'-diaminodi Phenylethane, 3,3'-diaminobiphenyl, 3,3'-dimethoxybenzidine, 4,4''-diamino-p-terphenyl, 3,3''-diamino-p-terphenyl, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, bis(p-aminocyclohexyl)methane, bis(p-β-amino-t-butylphenyl)ether, bis(p-β-methyl-d-aminopentyl)benzene, p-bis(2-methyl-4-aminopentyl)benzene , p-bis(1,1-dimethyl-5-aminopentyl)benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis(β-amino-t-butyl)toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, 2'-methoxy-4,4'-diaminobenzanilide, 4,4'-diaminobenzanilide, 1,Examples of aromatic diamine compounds include 3-bis[2-(4-aminophenyl)-2-propyl]benzene, 1,4-bis[2-(4-aminophenyl)-2-propyl]benzene, 1,4-bis(4-aminophenoxy)-2,5-di-tert-butylbenzene, 6-amino-2-(4-aminophenoxy)benzoxazole, 2,6-diamino-3,5-diethyltoluene, 2,4-diamino-3,5-diethyltoluene, 2,4-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, and bis(4-amino-3-ethyl-5-methylphenyl)methane. Among these, diamines represented by the following general formula (2) and diamines having a naphthalene skeleton are particularly preferred, as they are expected to enhance the linearity of polyimide molecular chains and achieve a low CTE due to in-plane orientation. These diamine compounds can be used alone or in combination of two or more. In this specification, a diamine residue derived from a diamine compound represented by general formula (2) may be referred to as a "diamine residue (2)."

[0109]

[0110] [In formula (2), the linking group X represents a divalent group selected from a single bond, -CONH-, or -COO-; Y independently represents hydrogen, a monovalent hydrocarbon group having 1 to 3 carbon atoms, or an alkoxy group; n represents an integer of 0 to 2; and p and q independently represent integers of 0 to 4.]

[0111] The diamine compound represented by general formula (2) has a rigid structure and can improve the planarity and rigidity of the polyimide, thereby improving the stacking interaction between molecular chains. Therefore, the diamine residue (2) has low mobility, which can reduce the dielectric loss tangent of the polyimide. Furthermore, by increasing the planarity of the polyimide molecular skeleton, the CTE in the in-plane direction can be reduced. Furthermore, preferably, by including a biphenyl group in the diamine residue (2), the molecular weight of the monomer-derived unit can be increased, thereby reducing the imide group concentration and resulting in a polyimide with low moisture absorption. This also reduces the dielectric loss tangent by reducing the moisture content within the molecular chain. Furthermore, when the acid dianhydride residue (1) contains a biphenyl skeleton as a common structure with the diamine residue (2), the polymer as a whole is more likely to form an ordered structure, which is effective in reducing the dielectric loss tangent.

[0112] Preferred examples of the diamine compound represented by general formula (2) include 1,4-phenylenediamine, 1,2-phenylenediamine, 1,3-phenylenediamine, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-diethyl-4,4'-diaminobiphenyl (m-EB), 2,2'-diethoxy-4,4'-diaminobiphenyl (m-EOB), 2,2'-dipropoxy-4,4'-diaminobiphenyl (m-POB), 2,2'-di-n-propyl-4,4'-diaminobiphenyl (m-NPB), 2,2'-divinyl-4,4'-diaminobiphenyl (VAB), 4,4'-diaminobiphenyl, and 4,4''-diamino-p-terphenyl. Among these, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB) is most preferable as it has a large effect of lowering the CTE and the dielectric loss tangent of the resin film.

[0113] The content of diamine residue (2) in the non-thermoplastic polyimide precursor of component (A1) is preferably 50 mol% or more, more preferably 60 mol% or more, and most preferably in the range of 70 to 100 mol%, based on the total diamine residues. If the content of diamine residue (2) is less than 50 mol%, the effect of lowering the CTE and dielectric loss tangent is not fully exerted. From the viewpoint of lowering the CTE and dielectric loss tangent, it is preferable to increase the proportion of diamine residue (2) in the total diamine residues as much as possible, and the content of diamine residue (2) may be 100 mol%.

[0114] The non-thermoplastic polyimide precursor of component (A1) can control its moisture absorption, dielectric properties, toughness, CTE, storage modulus, tensile modulus, etc. by selecting the types of tetracarboxylic dianhydride residues and diamine residues, or by selecting the molar ratios of two or more types of tetracarboxylic dianhydride residues or diamine residues when the non-thermoplastic polyimide precursor of component (A1) contains two or more structural units. Furthermore, when the non-thermoplastic polyimide precursor of component (A1) contains two or more structural units, they may be present as blocks or randomly, but are preferably present randomly.

[0115] Furthermore, the non-thermoplastic polyimide precursor of component (A1) preferably contains tetracarboxylic dianhydride residues and diamine residues derived from an aromatic tetracarboxylic dianhydride and an aromatic diamine residue derived from an aromatic diamine. By containing only tetracarboxylic dianhydride residues and diamine residues contained in the polyamic acid and polyimide, the dimensional accuracy of the resin film in a high-temperature environment can be improved.

[0116] The non-thermoplastic polyimide precursor of component (A1) can be produced by reacting the above-mentioned tetracarboxylic anhydride component and diamine component in a solvent. For example, the tetracarboxylic anhydride component and diamine component are dissolved in approximately equimolar amounts in an organic solvent and stirred at a temperature in the range of 0 to 100°C for 30 minutes to 24 hours to cause a polymerization reaction, thereby obtaining the non-thermoplastic polyimide precursor (polyamic acid) of component (A1). During the reaction, the reaction components are dissolved in the organic solvent so that the resulting precursor is in the range of 5 to 50 wt %, preferably 10 to 40 wt %, of the organic solvent. Examples of organic solvents used in the polymerization reaction include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethyl sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, methylcyclohexane, dioxane, tetrahydrofuran, diglyme, triglyme, methanol, ethanol, benzyl alcohol, and cresol. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination. The amount of such organic solvents used is not particularly limited, but it is preferable to adjust the amount used so that the concentration of the solution of the non-thermoplastic polyimide precursor (component (A1)) obtained by the polymerization reaction is about 5 to 50 wt %.

[0117] The synthesized non-thermoplastic polyimide precursor of component (A1) generally has excellent solvent solubility, so it is advantageous to use it as a reaction solvent solution, but if necessary, it can be concentrated, diluted, or replaced with another organic solvent. The viscosity of the solution of the non-thermoplastic polyimide precursor of component (A1) is preferably in the range of 100 cP to 100,000 cP.

[0118] (Component (B1)) Component (B1) is a soluble compound having a structural unit containing at least one of an aliphatic chain and an alicyclic skeleton. The soluble compound is at least one of a soluble polyimide and a soluble polyimide precursor. This soluble polyimide is a thermoplastic polyimide that is soluble in a solvent, and its precursor is a soluble polyimide precursor. In other words, the soluble polyimide of component (B1) is obtained by imidizing a soluble polyimide precursor (polyamic acid) of component (B1) obtained by reacting a tetracarboxylic acid anhydride component with a diamine component. The soluble polyimide has a structural unit containing at least one of an aliphatic chain and an alicyclic skeleton, which enables the resin film to have a low dielectric loss tangent.

[0119] From the viewpoint of sufficiently lowering the dielectric loss tangent, the component (B1) preferably contains 20% by weight or more, and more preferably 30 to 70% by weight, of structural units containing at least one of an aliphatic chain and an alicyclic skeleton in the polymer chain.

[0120] The structural unit containing at least one of an aliphatic chain and an alicyclic skeleton may be derived from a tetracarboxylic acid anhydride component or a diamine component. Component (B1) preferably has an aliphatic chain containing 10 or more carbon atoms, and more preferably has an aliphatic chain containing 10 to 54 carbon atoms. When the component (B1) has an aliphatic chain containing 10 or more carbon atoms, the dielectric loss tangent can be reduced.

[0121] "Weight-average molecular weight" The weight-average molecular weight of component (B1) is preferably in the range of 5,000 to 120,000, and more preferably in the range of 10,000 to 90,000. If the weight-average molecular weight of component (B1) is less than 5,000, the increased concentration of terminal functional groups will deteriorate the dielectric loss tangent and the toughness inherent in component (B1) will not be exhibited. On the other hand, if the weight-average molecular weight of component (B1) exceeds 120,000, the viscosity will increase excessively, making the component insoluble in solvents. The weight-average molecular weight can be measured by the method shown in the examples below.

[0122] "SP value" The SP value of the (B1) component is 15.0 to 24.5 (J / cm3 ) 1 / 2 When the SP value of the (A1) component and the SP value of the (B1) component satisfy predetermined conditions, when the (A1) component and the (B1) component are mixed, it is possible to lower the coefficient of linear expansion (CTE) and to easily reduce the dielectric loss tangent. The SP value of the (B1) component can be calculated based on the Fedors method, as with the SP value of the first resin according to the first embodiment. The SP value of the (B1) component is 23.5 (J / cm 3 ) 1 / 2 The SP value of the B1 component is preferably 18.0 (J / cm 3 ) 1 / 2 It is preferable that this is equal to or greater than this.

[0123] "Dielectric Loss Tangent" When the soluble polyimide of component (B1) is formed into a film by itself, the dielectric loss tangent (Df) at 10 GHz after 24 hours of conditioning under conditions of a temperature of 24 to 26°C and a relative humidity of 45 to 55% is preferably 0.0020 or less, more preferably 0.0016 or less. If the dielectric loss tangent exceeds 0.0020, the dielectric loss tangent after alloying will be insufficient. The dielectric loss tangent can be measured by the method described above.

[0124] "Tensile Modulus" The soluble polyimide of component (B1) preferably has a tensile modulus of 2.5 GPa or less when formed into a film by itself, more preferably in the range of 0.2 to 2.0 GPa. If the tensile modulus is 2.5 GPa or less, stress can be relaxed when alloyed, improving toughness. On the other hand, if the tensile modulus is greater than 2.5 GPa, stress relaxation does not occur, and toughness during alloying deteriorates. Furthermore, stress generated during thermal shrinkage cannot be relaxed, making it difficult to achieve low CTE characteristics. The tensile modulus can be measured by the method described above.

[0125] The tetracarboxylic acid anhydride component and diamine component used as raw materials for component (B1) are described below by giving preferred specific examples. The raw materials for the soluble polyimide precursor (polyamic acid) of component (B1) are the same as those for the soluble polyimide.

[0126] "Tetracarboxylic Acid Anhydride Component" For the component (B1), any tetracarboxylic acid anhydride generally used in thermoplastic polyimides can be used as a raw material without any particular restrictions. However, it is preferable to use tetracarboxylic acid anhydrides represented by the following general formulas (3) and / or (4). For example, it is preferable to use raw materials for the component (B1) that contain tetracarboxylic acid anhydrides represented by the following general formulas (3) and / or (4) in a total amount of 90 mol % or more relative to the total tetracarboxylic acid anhydride components. In other words, it is preferable for the component (B1) to contain tetracarboxylic acid residues derived from tetracarboxylic acid anhydrides represented by the following general formulas (3) and / or (4) in a total amount of 90 mol % or more relative to the total tetracarboxylic acid residues. By containing tetracarboxylic acid residues derived from tetracarboxylic acid anhydrides represented by the following general formulas (3) and / or (4) in a total amount of 90 mol % or more relative to the total tetracarboxylic acid residues, it is preferable to achieve both flexibility and heat resistance in the soluble polyimide of the component (B2). If the total amount of tetracarboxylic acid residues derived from the tetracarboxylic acid anhydrides represented by the following general formula (3) and / or (4) is less than 90 mol %, the solvent solubility of the soluble polyimide of component (B1) tends to decrease.

[0127]

[0128] In general formula (3), X represents a single bond or a divalent group selected from the following formulae, and in general formula (4), the cyclic moiety represented by Y represents the formation of a cyclic saturated hydrocarbon group selected from a 4-membered ring, a 5-membered ring, a 6-membered ring, a 7-membered ring, or an 8-membered ring:

[0129]

[0130] In the above formula, Z is -C ６ H ４ -, -(CH ２ ) n- or -CH ２ -CH(-OC(=O)-CH ３ )-CH ２ -, and n is an integer of 1 to 20.

[0131] Examples of the tetracarboxylic acid anhydride represented by the general formula (3) include 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA), 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride (BTDA), 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride (DSDA), 4,4'-oxydiphthalic anhydride (ODPA), 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA), p-phenylenebis(trimellitic acid monoester acid anhydride) (TAHQ), and ethylene glycol bisanhydrotrimellitate (TMEG).

[0132] Examples of the tetracarboxylic acid anhydride represented by the general formula (4) include 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride, 1,2,3,4-cyclopentanetetracarboxylic acid dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid dianhydride, 1,2,4,5-cycloheptanetetracarboxylic acid dianhydride, and 1,2,5,6-cyclooctanetetracarboxylic acid dianhydride.

[0133] In addition to the tetracarboxylic acid anhydrides represented by the general formulas (3) and (4), the component (B1) may contain tetracarboxylic acid residues derived from acid anhydrides generally used as raw materials for polyimides, as long as the effects of the invention are not impaired.

[0134] "Diamine Component" Component (B1) can be a diamine compound commonly used in the synthesis of thermoplastic polyimides. However, from the viewpoint of lowering the dielectric dissipation factor and improving the dielectric properties, it is preferable to use a diamine component containing aliphatic diamines in an amount of preferably 40 mol % or more, more preferably 60 mol % or more, and most preferably 80 to 100 mol % of the total diamine components. In other words, components (B1) and (B2) preferably contain diamine residues derived from aliphatic diamines in an amount of preferably 40 mol % or more, more preferably 60 mol % or more, and most preferably 80 to 100 mol % of the total diamine residues. By including diamine residues derived from aliphatic diamines in the above amounts, the dielectric properties of the polyimide are improved, and the thermocompression bonding properties are improved by lowering the glass transition temperature (Tg) of the polyimide, and internal stress is alleviated by lowering the elastic modulus. If the proportion of diamine residues derived from aliphatic diamines relative to the total diamine residues is less than 40 mol%, the effect of improving the dielectric tangent and thermocompression bonding properties may not be sufficiently obtained. Here, as the aliphatic diamine, for example, a dimer acid type diamine in which the two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups, hexamethylenediamine, dodecanediamine, cyclohexanediamine, polyoxyalkyleneamine, 4,4-diaminodicyclohexylmethane, etc. can be used, and a dimer acid type diamine is particularly preferred.

[0135] The dimer acid diamine is a mixture containing the following component (a) as the main component and optionally containing components (b) and (c), and it is preferable to use a purified product in which the amounts of components (b) and (c) are controlled: (a) dimer diamine; (b) monoamine compound obtained by substituting a terminal carboxylic acid group of a monobasic acid compound having 10 to 40 carbon atoms with a primary aminomethyl group or an amino group; (c) amine compound obtained by substituting a terminal carboxylic acid group of a polybasic acid compound having a hydrocarbon group having 41 to 80 carbon atoms with a primary aminomethyl group or an amino group (excluding the dimer diamine).

[0136] The dimer diamine of component (a) is a dimer acid in which the two terminal carboxylic acid groups (—COOH) of the dimer acid are replaced by primary aminomethyl groups (—CH ２ -NH ２ ) or amino group (-NH ２ ) is substituted with a diamine. Dimer acid is a known dibasic acid obtained by the intermolecular polymerization reaction of unsaturated fatty acids. Its industrial production process is largely standardized in the industry and is obtained by dimerizing unsaturated fatty acids having 11 to 22 carbon atoms using a clay catalyst or the like. Industrially obtained dimer acids are primarily composed of a 36-carbon dibasic acid obtained by dimerizing 18-carbon unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid. However, depending on the degree of purification, they may contain arbitrary amounts of monomer acid (18 carbon atoms), trimer acid (54 carbon atoms), and other polymerized fatty acids having 20 to 54 carbon atoms. Furthermore, although double bonds remain after the dimerization reaction, in this specification, dimer acids that have been further subjected to a hydrogenation reaction to reduce the degree of unsaturation are also included in the term dimer acid. The dimer diamine of component (a) can be defined as a diamine compound obtained by substituting the terminal carboxylic acid group of a dibasic acid compound having 18 to 54 carbon atoms, preferably 22 to 44 carbon atoms, with a primary aminomethyl group or an amino group.

[0137] Commercially available aliphatic diamines are available, such as Diamine H20 manufactured by Okamura Oil Mills, and PRIAMINE 1073 (trade name), PRIAMINE 1074 (trade name), and PRIAMINE 1075 (trade name) manufactured by Croda Japan.

[0138] The component (B1) may contain a diamine residue derived from a diamine compound generally used as a raw material for polyimides, provided that the effect of the invention is not impaired.

[0139] In the component (B1), by selecting the types of the tetracarboxylic acid anhydride component and the diamine component, or by selecting the respective molar ratios when two or more types of tetracarboxylic acid anhydride components or diamine components are used, it is possible to control the dielectric properties, CTE, tensile modulus, glass transition temperature, etc. Furthermore, when the component (B1) has a plurality of polyimide structural units, they may be present as blocks or randomly, but are preferably present randomly.

[0140] The soluble polyimide of component (B1) can be produced by reacting the above-mentioned tetracarboxylic anhydride component and diamine component in a solvent to produce the soluble polyimide precursor (polyamic acid) of component (B1), followed by heating and ring-closure. For example, the soluble polyimide precursor of component (B1) can be obtained by dissolving the tetracarboxylic anhydride component and diamine component in approximately equimolar amounts in an organic solvent and stirring the mixture at a temperature in the range of 0 to 100°C for 30 minutes to 24 hours to cause a polymerization reaction. During the reaction, the reaction components are dissolved in the organic solvent so that the resulting precursor is in the range of 5 to 50 wt %, preferably 10 to 40 wt %, of the organic solvent. Examples of organic solvents used in the polymerization reaction include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethyl sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, methylcyclohexane, dioxane, tetrahydrofuran, diglyme, triglyme, methanol, ethanol, benzyl alcohol, and cresol. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination. The amount of such organic solvents used is not particularly limited, but it is preferable to adjust the amount used so that the concentration of the solution of the soluble polyimide precursor (component (B1)) obtained by the polymerization reaction is about 5 to 50 wt %.

[0141] The synthesized soluble polyimide precursor of component (B1) generally has excellent solvent solubility, so it is advantageous to use it as a reaction solvent solution, but if necessary, it can be concentrated, diluted, or replaced with another organic solvent. The viscosity of the solution of the soluble polyimide precursor of component (B1) is preferably in the range of 50 cP to 100,000 cP.

[0142] The method for imidizing the soluble polyimide precursor of component (B1) to form the soluble polyimide of component (B1) is not particularly limited, and a suitable method is, for example, heat treatment in the solvent at a temperature in the range of 80 to 400° C. for 1 to 24 hours. The heating temperature may be constant, or the temperature may be changed during the process.

[0143] The soluble polyimide of component (B1) most preferably has a completely imidized structure. However, a portion of the polyimide may be an amic acid. The imidization rate can be determined by measuring the infrared absorption spectrum of a polyimide thin film using a Fourier transform infrared spectrophotometer (commercially available: JASCO Corporation, trade name: FT / IR620) by the single reflection ATR method, and determining the imidization rate at 1015 cm －１ The absorbance of the benzene ring absorption band near 1780 cm －１ It can be calculated from the ratio of the absorbance of the C═O stretching derived from the imide group to the absorbance of the C═O stretching derived from the imide group and a separately prepared calibration curve.

[0144] "Composition ratio" The weight ratio (B1 / A1) of the (B1) component to the (A1) component in the resin composition according to the second embodiment is preferably in the range of 15 / 85 to 83 / 17, and from the viewpoint of achieving the low dielectric properties derived from the (B1) component without inhibiting the in-plane orientation properties of the molecular chains derived from the (A1) component, is more preferably in the range of 25 / 75 to 75 / 25, even more preferably in the range of 30 / 70 to 70 / 30, and particularly preferably in the range of 40 / 60 to 70 / 30. If the weight ratio (B1 / A1) is less than 15 / 85, the effect of imparting heat resistance to the resin film and the effect of lowering the CTE may not be fully exhibited. If it exceeds 83 / 17, the effect of lowering the dielectric tangent of the resin film may not be fully exhibited, making it difficult to achieve both a low dielectric tangent and a low CTE.

[0145] Furthermore, from the viewpoint of fully exerting the effects of the present invention, the total amount of the component (A1) and the component (B1) in the resin composition may be more than 25% by weight, preferably 40% by weight or more, more preferably in the range of 50 to 100% by weight, and most preferably in the range of 80 to 100% by weight, based on the total weight.

[0146] "Optional Components" The resin composition according to this embodiment may further contain optional components such as inorganic fillers, organic fillers, plasticizers, curing accelerators, coupling agents, pigments, and flame retardants, as needed, within the scope of the invention. Examples of inorganic fillers include silicon dioxide, aluminum oxide, beryllium oxide, niobium oxide, titanium oxide, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, magnesium fluoride, potassium silicofluoride, and metal phosphinates. These may be used alone or in combination of two or more. Other resin components, such as epoxy resins, fluororesins, and olefin-based resins, may also be included as optional components.

[0147] (Coating Liquid) The coating liquid according to the second embodiment contains the resin composition according to the second embodiment and an organic solvent capable of dissolving the resin composition. Since the soluble polyimide of the component (B1) is soluble in a solvent, and the non-thermoplastic polyimide precursor of the component (A1) and the soluble polyimide precursor of the component (B1) also exhibit good solubility, the coating liquid according to the second embodiment can be prepared as a polyimide solution (varnish) containing a solvent. As the organic solvent, for example, it is preferable to use a mixed solvent obtained by mixing one or more selected from N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethyl sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, cresol, methyl ethyl ketone, hexane, methanol, ethanol, etc. with an aromatic hydrocarbon solvent such as xylene or toluene in any ratio.

[0148] A preferred example of the organic solvent used in the resin composition according to this embodiment is the combination of the following first solvent (component (C)) and second solvent (component (D)).

[0149] First solvent (component (C)): A solvent having an SP value (solubility parameter) of 5 to 9.5 (cal / cm ３ ) １／２ (10.3 to 19.5 (J / cm ３ ) １／２ The first solvent is a low-polarity solvent, and by using this, it becomes easy to prepare a varnish using the component (B1). That is, the component (B1) dissolves in the first solvent but is difficult to dissolve in the second solvent. As the first organic solvent, for example, toluene (SP value 8.9 (cal / cm ３ ) １／２ , 18.2 (J / cm ３ ) １／２ ), xylene (SP value 8.8 (cal / cm ３ ) １／２ , 18.0 (J / cm ３ ) １／２), tetrahydrofuran (THF; SP value 9.1 (cal / cm ３ ) １／２ , 18.6 (J / cm ３ ) １／２ ), hexane (SP value 7.3 (cal / cm ３ ) １／２ , 15.0 (J / cm ３ ) １／２ ) diethyl ketone (SP value 8.8 (cal / cm ３ ) １／２ , 18.0 (J / cm ３ ) １／２ ), butyl acetate (SP value 8.5 (cal / cm ３ ) １／２ , 17.4 (J / cm ３ ) １／２ ), diethyl carbonate (SP value 8.8 (cal / cm ３ ) １／２ , (18.0J / cm ３ ) １／２ It is preferable to use two or more of these in combination. The SP value of a solvent means the Hildebrand solubility parameter.

[0150] Second solvent (component (D)): SP value (solubility parameter) of 9.6 to 15 (cal / cm ３ ) １／２ (19.7~30.8 (J / cm ３ ) １／２ The second solvent (component (D)) is a highly polar solvent, and its use facilitates the preparation of a varnish using component (A1). In other words, component (A1) dissolves in the second solvent. Examples of the second organic solvent include N,N-dimethylacetamide (DMAc; SP value 10.8 (cal / cm ３ ) １／２ , 22.1 (J / cm ３ ) １／２ ), N,N-dimethylformamide (DMF; SP value 12.1 (cal / cm ３ ) １／２ , 24.8 (J / cm ３ ) １／２ )), N-methyl-2-pyrrolidone (NMP; SP value 11.3 (cal / cm ３ )１／２ , 23.1 (J / cm ３ ) １／２ ), cyclohexanone (SP value 9.9 (cal / cm ３ ) １／２ , 20.3 (J / cm ３ ) １／２ ), methanol (SP value 14.8 (cal / cm ３ ) １／２ , 30.3 (J / cm ３ ) １／２ ), acetonitrile (SP value 11.9 (cal / cm ３ ) １／２ , 24.3 (J / cm ３ ) １／２ ) gamma-butyrolactone (SP value 12.6 (cal / cm ３ ) １／２ , 25.8 (J / cm ３ ) １／２ ), dimethyl sulfoxide (SP value 14.5 (cal / cm ３ ) １／２ , 29.7 (J / cm ３ ) １／２ ), dimethyl carbonate (SP value 9.9 (cal / cm ３ ) １／２ , 20.3 (J / cm ３ ) １／２ These may be used in combination of two or more kinds.

[0151] The SP value of the first solvent (SP Ｃ ) and the SP value of the second solvent (SP Ｄ ) difference (SP Ｃ -SP Ｄ ) is 0.5 (cal / cm ３ ) １／２ ((1.0(J / cm ３ ) １／２ ) or more, and 1.0 (cal / cm ３ ) １／２ ((2.1(J / cm ３ ) １／２ ) or more is more preferable, and 5.0 (cal / cm ３ ) １／２ ((10.3(J / cm ３ ) １／２ ) is more preferably less than the difference (SPＣ When the absolute value of the SP value (SPD) of the first solvent is 0.5 or more, the components (A1) and (B1) are easily mixed together, and a uniform varnish can be obtained. When two or more types of the first solvent or the second solvent are used in combination, the absolute value of the SP value (SP Ｃ ) and the SP value of the second solvent (SP Ｄ ) is the difference (SP) between the average values ​​of two or more types. Ｃ -SP Ｄ ) can be calculated.

[0152] The volume ratio (C / D) of the first solvent (C) to the second solvent (D) in the coating liquid according to the second embodiment is preferably within a range of 5 / 95 to 95 / 5, and more preferably within a range of 10 / 90 to 90 / 10, which makes it easier to prepare a varnish by mixing the components (A1) and (B1).

[0153] The total content of the solvent is not particularly limited, but it is preferable to adjust the concentration of the total amount of the (A1) component and the (B1) component to about 5 to 30% by weight of the entire resin composition.

[0154] "Viscosity" The viscosity of the coating liquid according to the second embodiment is not particularly limited, but is preferably in the range of 100 to 100,000 cP, more preferably 500 to 50,000 cP, to improve the handleability when applying the coating liquid and facilitate the formation of a coating film of uniform thickness. If the viscosity is within the above range, it is possible to prevent defects such as uneven thickness and streaks from occurring in the film during the coating operation using a coater or the like.

[0155] "Preparation of Resin Composition" The resin composition according to the second embodiment can be produced by mixing the (A1) component and the (B1) component. In this case, it is preferable to mix the components in the form of a resin solution dissolved in a solvent. For example, a resin solution of the non-thermoplastic polyimide precursor of the (A1) component may be blended into a resin solution (varnish) of the (B1) component and mixed, or a resin solution of the (B1) component may be blended into a resin solution (varnish) of the non-thermoplastic polyimide precursor of the (A1) component and mixed. The resin composition according to the second embodiment is obtained by removing the solvent from the coating liquid prepared by mixing. In other words, the solid content of the coating liquid according to the second embodiment is the resin composition according to the second embodiment.

[0156] The acid or amine terminals of the (A1) and (B1) components can be adjusted by adjusting the molar ratio of the tetracarboxylic anhydride component and the diamine component used as raw materials. For example, by adjusting the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component / diamine component) to less than 1.0, the (A1) and (B1) components can be amine-terminated. On the other hand, by adjusting the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component / diamine component) to greater than 1.0, the (A1) and (B1) components can be acid-terminated. The term "acid terminal" refers to a state in which an acid anhydride group or a carboxyl group (—COOH) is present at the end of the polymer chain, and the term "amine terminal" refers to a state in which an amino group is present at the end of the polymer chain.

[0157] When preparing the resin composition according to this embodiment, when an acid-terminated (A1) component is used, it is preferable to use an acid-terminated (B1) component as well. When an amine-terminated (A1) component is used, it is preferable to use an amine-terminated (B1) component as well. In this way, by mixing the (A1) and (B1) components in an acid-terminated or amine-terminated state, the reaction between the (A1) and (B1) components is suppressed, and a resin composition containing the (A1) and (B1) components in their original polymeric state can be prepared, making it easier to achieve the desired properties. Furthermore, the (A1) and (B1) components may be mixed using a stirring blade, or may be mixed using a stirring method that applies high shear to the resin composition, such as a bead mill or a planetary stirrer. During mixing, the use of a first solvent and a second solvent as solvents facilitates preparation of the resin composition. The first solvent and the second solvent are preferably used so that the volume ratio (C / D) of the first solvent (C) to the second solvent (D) in the final resin composition is within the range of 5 / 95 to 95 / 5, more preferably within the range of 10 / 90 to 90 / 10.

[0158] When preparing the resin composition according to the second embodiment, the (A1) and (B1) components may be used with their terminal groups blocked. That is, when an acid-terminated (A1) component is used, the (B1) component may be acid-terminated or the acid terminal may be blocked with a monoamine. When an amine-terminated (A1) component is used, the (B1) component may be amine-terminated or the amine terminal may be blocked with an aromatic carboxylic acid. Furthermore, the terminal groups of the (A1) and (B1) components may each be blocked. By using a polymer with blocked terminal functional groups, it becomes easy to prepare a resin composition containing the (A1) and (B1) components in their original polymer state.

[0159] The resin composition according to the present embodiment, when used to form an adhesive layer, exhibits excellent flexibility and thermoplasticity, and therefore has favorable properties for applications such as materials for insulating layers in circuit boards such as FPCs, rigid boards, rigid-flex boards, multilayer boards, build-up boards, and high-frequency boards, as well as coating agents.

[0160] (Resin Film) The resin film according to the second embodiment is a resin film consisting of a single layer or multiple layers, and at least one layer thereof contains the following components (A2) and (B2) as resin components: (A2): a non-thermoplastic polyimide, and (B2): a soluble polyimide having a structural unit including an aliphatic chain or an alicyclic skeleton. The SP value of the component (A2) is 24.6 to 33.3 (J / cm 3 ) 1 / 2 and the SP value of component (B2) is 15.0 to 24.5 (J / cm 3 ) 1 / 2 The component (B2) is a polyimide obtained by imidizing the polyimide precursor of the component (B1). The second resin film is a polyimide layer (X) obtained by using the above resin composition to imidize the polyimide precursor and form it into a film. Here, the non-thermoplastic polyimide of the component (A2) is obtained by imidizing the non-thermoplastic polyimide precursor of the component (A1) described in the resin composition according to the second embodiment. The resin film according to the second embodiment contains the components (A2) and (B2) and thus has excellent high-frequency characteristics and a low CTE.

[0161] The resin film according to the second embodiment is preferably produced by, for example, repeatedly applying and drying the coating liquid according to the second embodiment to a supporting substrate one or more times, and then imidizing the polyamic acid, such as the non-thermoplastic polyimide precursor of component (A1), contained in the coating film. The method for applying the coating liquid according to the second embodiment to the supporting substrate is not particularly limited, and application can be performed using a coater such as a comma coater, a die coater, a knife coater, or a lip coater. The imidization method is not particularly limited, and a heat treatment is preferably employed, for example, heating at a temperature in the range of 80 to 400°C for 1 to 24 hours. The heating temperature may be constant, or the temperature may be changed during the process. The components (A2) and (B2) are most preferably fully imidized. However, a portion of the polyimide may be an amic acid. The imidization rate can be determined by measuring the infrared absorption spectrum of the polyimide thin film using a Fourier transform infrared spectrophotometer (commercially available: JASCO Corporation, product name: FT / IR620) using the single-reflection ATR method, and the imidization rate can be measured at a wavelength of 1015 cm. －１ The absorbance of the benzene ring absorption band near 1780 cm －１ It can be calculated from the ratio of the absorbance of the C=O stretching derived from the imide group and a separately prepared calibration curve. The calibration curve can be prepared based on the data of a sample whose imidization rate is known. In addition, by using a metal foil as the supporting substrate, the metal-clad laminate according to the present embodiment described below can be produced.

[0162] In the resin film according to the second embodiment, the weight ratio (B2 / A2) of the (B2) component to the (A2) component is preferably in the range of 15 / 85 to 83 / 17, more preferably 25 / 75 to 75 / 25. From the viewpoint of achieving the low dielectric properties of the (B2) component without inhibiting the in-plane orientation properties of the molecular chains derived from the (A2) component, a range of 30 / 70 to 70 / 30 is more preferable, and a range of 40 / 60 to 70 / 30 is most preferable. If the weight ratio (B2 / A2) is less than 15 / 85, the (B2) component may inhibit the in-plane orientation of the molecular chains, and the effect of lowering the CTE may not be fully exhibited. On the other hand, if the weight ratio (B2 / A2) exceeds 83 / 17, the low dielectric component relative to the resin may be too low, resulting in insufficient low dielectric properties.

[0163] Furthermore, from the viewpoint of fully exerting the effects of the invention, the total amount of the component (A2) and the component (B2) in the resin film according to the second embodiment may be more than 25% by weight, preferably 40% by weight or more, more preferably in the range of 50 to 100% by weight, and most preferably in the range of 80 to 100% by weight, based on the total weight of the polyimide layer (X).

[0164] The resin film according to the second embodiment is not particularly limited as long as it is an insulating resin film containing the above-mentioned polyimide layer (X), and may be a film (sheet) made of insulating resin alone, or may be an insulating resin film laminated on a substrate such as a resin sheet, such as a copper foil, a glass plate, a polyimide film, a polyamide film, or a polyester film.

[0165] (Thickness) The resin film according to the second embodiment preferably has a thickness in the range of, for example, 5 to 150 μm, and more preferably in the range of, for example, 8 to 125 μm. If the thickness of the resin film is 5 μm or more, defects such as wrinkles occurring during transport in the production of the resin film can be reduced, sufficient toughness is exhibited, and self-supporting properties are easily obtained. On the other hand, if the thickness of the resin film is 150 μm or less, productivity of the resin film can be improved.

[0166] (Dielectric Constant) In order to ensure impedance matching when used in a circuit board such as an FPC and to reduce electrical signal loss, the resin film according to the second embodiment preferably has a dielectric constant (Dk) at 10 GHz after 24 hours of conditioning under conditions of a temperature of 24 to 26°C and a relative humidity of 45 to 55% of 3.5 or less, more preferably 3.0 or less. If this dielectric constant exceeds 3.5, problems such as electrical signal loss are likely to occur in the transmission path of high-frequency signals when used in a circuit board such as an FPC. The dielectric constant can be measured by the method described above.

[0167] (Dielectric Dissipation Factor) Furthermore, in order to reduce electrical signal loss when used in a circuit board such as an FPC, the resin film according to the second embodiment preferably has a dielectric dissipation factor (Df) at 10 GHz after 24 hours of humidity conditioning under conditions of a temperature of 24 to 26°C and a relative humidity of 45 to 55%, of 0.0040 or less, more preferably 0.0030 or less, and even more preferably 0.0025 or less. If the dielectric dissipation factor exceeds 0.0040, problems such as electrical signal loss are likely to occur in the transmission path of high-frequency signals when used in a circuit board such as an FPC. The dielectric dissipation factor can be measured by the method described above.

[0168] (CTE) The resin film according to the second embodiment preferably has a CTE of 50.0 ppm / K or less, more preferably in the range of 0 to 30.0 ppm / K. By having a CTE of 50.0 ppm / K or less, the dimensional change rate can be easily controlled when the resin film is made into a resin film or a metal-clad laminate. The CTE can be measured by the method described above.

[0169] (Glass transition temperature) The resin film according to the second embodiment preferably has a glass transition temperature (Tg) of 180°C or higher, and more preferably in the range of 180°C to 380°C. When the resin film according to the second embodiment has a Tg of 180°C or higher, it can achieve heat resistance that enables use in mounting and in high-temperature environments. The glass transition temperature can be measured by the method described above.

[0170] (Tensile Modulus of Elasticity) The resin film according to the second embodiment preferably has a tensile modulus of elasticity of 1.0 GPa or more, more preferably in the range of 1.5 GPa to 6.0 GPa, and even more preferably in the range of 1.5 GPa to 5.0 GPa. If the resin film has a tensile modulus of elasticity of 1.0 GPa or more, a film that is easy to process is likely to be obtained. The tensile modulus of elasticity can be measured by the method described above.

[0171] (Elongation) The resin film according to the second embodiment preferably has an elongation of 1% or more, more preferably 5% or more. If the elongation is 1% or more, the toughness can be improved. The elongation can be measured by the method described above.

[0172] (Storage Modulus) The resin film according to the second embodiment has a storage modulus of 1.0×10 at 180° C. ６ Pa or more, and ６ Pa ~ 10 x 10 ９ It is more preferable that the storage modulus is in the range of Pa. When the storage modulus is in the above range, heat resistance that enables use in mounting and in high-temperature environments can be achieved. The storage modulus can be measured by the method described above.

[0173] In the resin composition according to the second embodiment, the component (A2) forms a continuous phase (continuous structure). Here, the component (A2) forming a continuous phase means that the regions in which the component (A2) is present are continuously connected throughout the entire resin composition. In the resin composition according to the second embodiment, the phase structure of the resin composition is not particularly limited as long as the component (A2) forms a continuous phase. The resin composition may be a homogeneous phase (homogeneous compatible structure) in which the component (A2) and the component (B2) are compatible with each other, or may have a phase-separated structure such as a sea-island structure or an interconnected structure. When the phase structure of the resin composition according to the second embodiment is a sea-island structure, the component (A2) forms a sea phase. The component (A2) being a continuous phase allows the component (A2) to exhibit a low linear expansion coefficient.

[0174] When the phase structure of the resin composition according to the second embodiment is an island-sea structure, the island phases preferably consist of component (B2). The average equivalent circle diameter of the island phases is preferably 0.001 μm to 20 μm. By setting the average equivalent circle diameter of the island phases to 0.010 μm to 10 μm, the linear expansion coefficient can be reduced. The equivalent circle diameter of the island phases refers to the diameter of a circle having an area equal to the area of ​​the island phases.

[0175] When the phase structure of the resin composition according to the second embodiment is an island-sea structure, the number density of island phases having a circle equivalent diameter of 500 nm or more is 0.01 to 0.300 pieces / μm ２ It is preferable that the number density is 0.05 to 0.200 particles / μm ２ Therefore, the linear expansion coefficient can be further reduced.

[0176] When the phase structure of the resin composition according to the second embodiment is a homogeneous compatible structure, it may have island phases in part. In this case, the number density of island phases having a circle equivalent diameter of 500 nm or more is 0.01 pieces / μm ２ The number density is preferably 0.01 particles / μm or less. ２ If the phase structure of the resin composition according to the second embodiment is a homogeneous compatible structure, there is basically no island phase, so the lower limit of the number density is 0.

[0177] "Confirmation of the continuous phase, measurement of the average circle-equivalent diameter and number density of the island phases" The continuous phase can be confirmed and the average circle-equivalent diameter and number density of the island phases can be measured using the following method. The resin film is cut and embedded in epoxy resin, and then a cross section of the film is exposed using a cross section polisher (CP). Osmium is vapor-deposited on the obtained cross section depending on the sample, and a sample of approximately 7 mm is prepared for cross-sectional observation.

[0178] The cross-section of the above-mentioned sample for cross-section observation was observed in the thickness direction using a scanning electron microscope (SEM, e.g., JEOL Ltd., product name: JSM-IT500HR) at an acceleration voltage of 10 kV, a probe current of 80 μA, and a magnification of 3000x. The dark areas in the SEM observation were considered to be component (B2). The light areas were determined to be component (A2). The composition and ratio of each resin could be confirmed using microscopic Raman analysis or an energy dispersive electron X-ray spectrometer (EDX). Image analysis was performed using various analytical software (e.g., Image Pro 10) to confirm the continuous phase, calculate the average circle-equivalent diameter of the island phases, and calculate the number density of island phases 500 nm or larger per unit area (calculate the number of islands 500 nm or larger per unit area). Specifically, the three SEM images obtained by observing the phase separation structure were analyzed using analytical software (e.g., Image Pro 10), and the averages were used to calculate the respective values. The analysis conditions can be changed as appropriate depending on the sample, but for example, the analysis process may be performed after removing noise using spatial calibration, a median filter, or the like.

[0179] The region where the component (A2) is present is determined as follows. When the phase structure of the resin composition according to the second embodiment is a phase-separated structure such as a sea-island structure, the proportion of resins constituting each phase (e.g., sea phase, island phase) is examined using a Raman microscope or the like. The phase (region) where the proportion of the component (A2) is higher than the proportion of the first resin is determined to be the region where the component (A2) is present.

[0180] If the region in the SEM image where the component (A2) is present is continuously connected from one end of the image to the other, the component (A2) is determined to constitute a continuous phase.

[0181] When the phase structure of the resin composition according to the second embodiment is a homogeneous compatible structure, if the presence of component (A2) can be confirmed by microscopic Raman or the like, the entire homogeneous phase is determined to be the region where component (A2) is present. In this case, component (A2) is determined to constitute the continuous phase.

[0182] The resin film according to the second embodiment is useful as a material for insulating layers in circuit boards and the like because it can achieve both a low dielectric tangent and a low CTE.

[0183] <Metal-clad laminate> The metal-clad laminate according to the second embodiment comprises an insulating resin layer and a metal layer laminated on one or both surfaces of the insulating resin layer, and at least one insulating resin layer is made of the resin film. Note that the metal-clad laminate according to the second embodiment may also include any layer other than those described above.

[0184] The material of the metal layer is not particularly limited, but examples thereof include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof. Among these, copper or copper alloys are particularly preferred. The material of the wiring layer in the circuit board of this embodiment, which will be described later, is the same as that of the metal layer.

[0185] The thickness of the metal layer is not particularly limited, but when a metal foil such as copper foil is used, it is preferably 35 μm or less, and more preferably in the range of 5 to 25 μm. From the viewpoint of production stability and handling, the lower limit of the thickness of the metal foil is preferably 5 μm. When copper foil is used, it may be rolled copper foil or electrolytic copper foil. Furthermore, commercially available copper foil may be used as the copper foil.

[0186] The surface roughness of the metal layer is not particularly limited, but from the viewpoint of ensuring adhesion to the adhesive layer while reducing conductor loss, it is preferable that the metal layer has a roughened surface with a ten-point average roughness (Rzjis) in the range of 0.3 to 1.5 μm. Furthermore, the metal foil may be subjected to a surface treatment, for example, with siding, aluminum alcoholate, aluminum chelate, silane coupling agent, etc., for the purpose of, for example, rust prevention treatment or improving adhesive strength.

[0187] <Circuit Board> The circuit board according to the second embodiment is formed by wiring the metal layer of the metal-clad laminate. One or more metal layers of the metal-clad laminate are patterned by a conventional method to form a wiring layer (conductor circuit layer), thereby producing a circuit board such as an FPC. The circuit board may also include a coverlay film that covers the wiring layer.

[0188] <Electronic Device / Electronic Device> The electronic device and electronic device according to the second embodiment include the circuit board described above. Examples of the electronic device according to this embodiment include display devices such as liquid crystal displays, organic EL displays, and electronic paper, as well as organic EL lighting, solar cells, touch panels, camera modules, inverters, converters, and components thereof. Examples of the electronic device include HDDs, DVDs, mobile phones, smartphones, tablet devices, automotive electronic control units (ECUs), power control units (PCUs), and the like. In these electronic devices and electronic devices, the circuit board is preferably used as a component, such as wiring for moving parts, cables, and connectors.

[0189] The features of the present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to these examples. In the following examples, various measurements and evaluations are as follows, unless otherwise specified.

[0190] Measurement of Weight-Average Molecular Weight (Mw) and Number-Average Molecular Weight (Mn) The weight-average molecular weight and number-average molecular weight were measured using a gel permeation chromatograph (Tosoh Corporation, HLC-8420GPC, GPC column: one TSKgel α-M (Tosoh Corporation, inner diameter 7.8 mm × length 30 cm)). The sample solution was adjusted to a solids concentration of 0.1%. It was then filtered using a 0.45 μm filter. The resulting filtrate was used as the measurement sample solution. Polystyrene was used as the standard substance, and tetrahydrofuran (THF), N,N-dimethylacetamide (DMAc), or other developing solvents were used depending on the solubility of the resin. The flow rate was 0.8 mL / min, the measurement temperature was 40°C, and the sample injection volume was 100 μL. The results are shown in Table 1A.

[0191] "Viscosity Measurement" The viscosity at 25°C was measured using an E-type viscometer (manufactured by Brookfield, trade name: DV-II+Pro). The rotation speed was set so that the torque was 10% to 90%, and the viscosity was read when it stabilized 2 minutes after the start of measurement. The results are shown in Tables 1A, 2A, and 4A.

[0192] "Measurement of storage modulus and glass transition temperature (Tg)" The storage modulus was measured using a dynamic viscoelasticity measuring device (DMA: manufactured by TA Instruments, trade name: RSA G2) on a polyimide film measuring 5 mm wide x 70 mm long, at a temperature rise rate of 4°C / min from 30°C to 500°C and a frequency of 1 Hz. The peak value of Tan δ at the maximum temperature during the measurement was defined as the glass transition temperature (Tg). The obtained results are shown in Tables 1B, 2B, and 4B. The storage modulus at 30°C measured using the DMA was 1.0 x 10 ９ Pa or more, and the storage modulus in the temperature range within the glass transition temperature + 30°C is 1.0 × 10 ７ A thermoplastic resin exhibiting a storage modulus of less than 1.0 × 10 Pa at 30°C is considered to be "thermoplastic," and ９ Pa or more, and the storage modulus in the temperature range within the glass transition temperature + 30°C is 1.0 × 10 ７ Those exhibiting a hardness of 0.1 Pa or more were rated as "non-thermoplastic."

[0193] "Confirmation of the continuous phase" The continuous phase was confirmed by the following method. The resin film was cut and embedded in epoxy resin, and then the cross section of the film was exposed using a cross section polisher (CP). Osmium was vapor-deposited on the obtained cross section, and a sample of approximately 7 mm for cross-sectional observation was prepared.

[0194] The cross-sections of the above-mentioned samples for cross-section observation were observed in the thickness direction using a scanning electron microscope (SEM, for example, JEOL Ltd., product name: JSM-IT500HR) at an acceleration voltage of 10 kV, a probe current of 80 μA, and a magnification of 3000x. In the SEM observation, the black areas were determined to be the first resin, and the gray areas were determined to be the second resin. When the sea phase was the second resin (component (A2)), the second resin was determined to constitute a continuous phase and marked with a circle. When it did not constitute a continuous phase, it was marked with an X. When it had a phase-separated structure, it was marked with an A, and when it had a homogeneous phase, it was marked with a B. The results are shown in Table 2B. Experiments 1 to 5, 8 to 13, and 16 to 20 had a sea-island structure, Experiments 6 and 7 had a homogeneous phase, and Experiments 14 and 15 had an interconnected structure.

[0195] "Measurement of Linear Expansion Coefficient" Using Hitachi High-Technologies Corporation (formerly Seiko Instruments Inc.), product name: TMA / 7100, a sample (3 mm wide x 20 mm long) was heated from 30°C to 180°C at a constant heating rate while applying a load of 5.0 g, and then held at that temperature for 10 minutes, followed by cooling at a rate of 5°C / min, to determine the average thermal expansion coefficient (linear expansion coefficient) from 180°C to 100°C. The results obtained are shown in Tables 1B, 2B, and 4B.

[0196] "SP Value" The SP value (solubility parameter) of the resin was calculated based on the Fedors method described in Non-Patent Document 2. The SP value δ according to the Fedors method was calculated using the above formula (1). Specifically, the cohesive energy and molecular volume were calculated for each structure constituting the resin, and the SP value was calculated by dividing the sum of the cohesive energies of each component by the sum of the molecular volumes and raising the value to the 1 / 2 power. For example, in the case of the solvent-soluble polyimide resin A of Synthesis Example 1, when the diamine component is in excess relative to the acid anhydride based on the acid-amine ratio, both terminal structures of the resin become amine structures. The amount of these amine structures at both terminals was assumed to be the same as the amount of diamine component in excess relative to the acid anhydride, and the SP value of the amine structures at both terminals was assumed to be the same as the SP value of the diamine component. The calculation was then performed separately for the polyimide component that did not contain the terminal structure resulting from the reaction of acid anhydride and diamine, and the diamine component corresponding to the amine structures at both terminals. The cohesive energy and molecular volume of the polyimide structure, which is a repeating structure of the polyimide component, were calculated, and the cohesive energy and molecular volume of the diamine component, which is in excess of the acid anhydride, was calculated for a structure containing an amino group. Assuming that the polyimide component and diamine are present at a ratio of 0.975:0.025 based on the acid-amine ratio, the cohesive energy of the polyimide component and diamine component, weighted by the abundance ratio, was divided by the molecular volume of each component, weighted by the abundance ratio, and the result was raised to the 1 / 2 power to obtain an SP value of 20.5 J / cm. 3 The results are shown in Table 1B. The SP value was calculated based on the imide structure and amic acid structure, taking into account the acid-amine ratio.

[0197] [Measurement of Relative Dielectric Constant (Dk) and Dielectric Loss Tangent (Df)] The relative dielectric constant (Dk) and dielectric loss tangent (Df) of the polyimide film at a frequency of 10 GHz were measured using a vector network analyzer (manufactured by Agilent, product name: E8363C) and a split post dielectric resonator (SPDR resonator). Note that the Dk and Df values ​​after humidity control were measured after the polyimide film used for the measurement was left for 24 hours under conditions of a temperature of 24-26°C and a relative humidity of 45-55%. The results are shown in Tables 1B, 2B, and 4B. For Experiment No. 3 only, the relative dielectric constant and dielectric loss tangent were measured at frequencies of 28 GHz and 60 GHz using a network analyzer (manufactured by Keysight Technologies, product name: Network Analyzer N5290A) and a split cylinder resonator (SCR) under conditions of a relative humidity of 45-55% after leaving the film for 24 hours. The results are shown in Table 3.

[0198] [Measurement of tensile modulus and elongation] A tensile test was carried out on a polyimide film having a width of 12.7 mm and a length of 127 mm at a temperature of 23°C and a relative humidity of 50% RH at a rate of 50 mm / min using a Strograph R-1 (manufactured by Toyo Seiki Seisakusho, Ltd.), and the tensile modulus and elongation of the polyimide film were calculated. The results are shown in Tables 1B, 2B, and 4B.

[0199] [Measurement of Copper Foil Surface Roughness] The surface roughness of the copper foil was measured in tapping mode using an AFM (manufactured by Bruker AXS, trade name: Dimension Icon SPM) and a probe (manufactured by Bruker AXS, trade name: TESPA (NCHV), tip curvature radius 10 nm, spring constant 42 N / m) over an area of ​​80 μm × 80 μm on the copper foil surface, and the ten-point average roughness (Rzjis) was determined. The copper foil was fixed to a smoothly polished metal plate with a liquid adhesive. The ten-point average roughness Rzjis was determined after performing a leveling process to correct for tilt using the software provided with the AFM device. The surface roughness Rzjis of the copper foil was 0.6 μm.

[0200] The abbreviations used in the examples and comparative examples represent the following compounds. DDA: aliphatic diamine having 36 carbon atoms (PRIAMINE 1075 manufactured by Croda Japan Co., Ltd., amine value: 209 mg KOH / g); m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl; TPE-R: 1,3-bis(4-aminophenoxy)benzene; BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride; 6FDA: 4,4'-(hexafluoroisopropylidene)diphthalic anhydride; 26DHN-TME: 2,6-naphthalenebis(trimellitic acid monoester anhydride) (CAS number: 115383-00-1); BP-TME: p-biphenylenebis(trimellitic acid monoester anhydride), CAS number: 10340-81-5); NMP: N-methyl-2-pyrrolidone. DMAc: N,N-dimethylacetamide Xylene: (a mixture of ortho-, meta-, and para-xylene isomers) Elastomer: Kraton, trade name: MD1653MO (hydrogenated polystyrene elastomer, styrene unit content: 31% by weight, Mw: 80,499, acid value: none)

[0201] Synthesis Example 1: 20.1277 g of 6FDA (0.04523 mol), 24.9050 g of DDA (0.04639 mol), 63.05 g of NMP, and 42.03 g of xylene were added to a 500 mL separable flask and thoroughly mixed at 40°C for 1 hour to prepare a polyamic acid solution. This polyamic acid solution was heated to 190°C and stirred for 5 hours. Xylene was added in an amount to achieve the solids concentration shown in Table 1A, and imidization was completed to prepare solvent-soluble polyimide solution A. The solvent-soluble polyimide contained in solvent-soluble polyimide solution A was amine-terminated. Evaluation results for solvent-soluble polyimide solution A and the resulting resin film are shown in Tables 1A and 1B. Note that the evaluation results for each resin in Table 1B are the results after imidization, except for the elastomer of Sample No. 13.

[0202] Synthesis Example 2: A 500 mL separable flask was charged with 26.4329 g of 6FDA (0.05939 mol), 33.5671 g of DDA (0.06252 mol), 84 g of NMP, and 56 g of xylene, and the mixture was thoroughly mixed at 40°C for 1 hour to prepare a polyamic acid solution. The temperature of this polyamic acid solution was raised to 190°C, and the mixture was heated and stirred for 5 hours. Xylene was added so that the solids concentration after polymerization reached the solids concentration shown in Table 1A, and a solvent-soluble polyimide solution B (in which imidization was completed) was prepared. The solvent-soluble polyimide contained in solvent-soluble polyimide solution B was amine-terminated. The evaluation results of solvent-soluble polyimide solution B and the resulting resin film are shown in Tables 1A and 1B.

[0203] Synthesis Example 3: 25.7985 g of 6FDA (0.05797 mol), 34.2015 g of DDA (0.06370 mol), 84 g of NMP, and 56 g of xylene were added to a 500 mL separable flask and mixed thoroughly at 40 ° C. for 1 hour to prepare a polyamic acid solution. This polyamic acid solution was heated to 190 ° C., heated and stirred for 5 hours, and xylene was added so that the solids concentration after polymerization reached the solids concentration shown in Table 1A to prepare a solvent-soluble polyimide solution C in which imidization was completed. The solvent-soluble polyimide contained in the solvent-soluble polyimide solution C was amine-terminated. The evaluation results of the solvent-soluble polyimide solution C and the resulting resin film are shown in Tables 1A and 1B.

[0204] Synthesis Example 4: 28.6160 g of 6FDA (0.06430 mol), 31.3840 g of DDA (0.05845 mol), 84 g of NMP, and 56 g of xylene were added to a 500 mL separable flask and mixed thoroughly at 40 °C for 1 hour to prepare a polyamic acid solution. This polyamic acid solution was heated to 190 °C, heated and stirred for 5 hours, and xylene was added so that the solids concentration after polymerization reached the solids concentration shown in Table 1A to prepare a solvent-soluble polyimide solution D in which imidization was completed. The solvent-soluble polyimide contained in solvent-soluble polyimide solution D is acid-terminated. Evaluation results of solvent-soluble polyimide solution D and the resulting resin film are shown in Tables 1A and 1B.

[0205] Synthesis Example 5: 20.9187 g of BPDA (0.07097 mol), 39.0813 g of DDA (0.07279 mol), 84 g of NMP, and 56 g of xylene were added to a 500 mL separable flask and mixed thoroughly at 40°C for 1 hour to prepare a polyamic acid solution. This polyamic acid solution was heated to 190°C and stirred for 5 hours. Xylene was added so that the solids concentration after polymerization reached the solids concentration shown in Table 1A, preparing a solvent-soluble polyimide solution E in which imidization was completed. The solvent-soluble polyimide contained in solvent-soluble polyimide solution E was acid-terminated. Evaluation results of solvent-soluble polyimide solution E and the resulting resin film are shown in Tables 1A and 1B.

[0206] (Synthesis Example 6) Under a nitrogen stream, 9.2063 g of m-TB (0.04331 mol) and an amount of NMP such that the solids concentration after polymerization was 15 wt% were added to a 500 mL separable flask and stirred at room temperature to dissolve. Next, 20.7937 g of 26DHN-TME (0.04049 mol) was added, and the polymerization reaction was continued with stirring at room temperature for one week to prepare non-thermoplastic polyamic acid solution F. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution F was amine-terminated. The evaluation results of non-thermoplastic polyamic acid solution F and the resulting resin film are shown in Tables 1A and 1B.

[0207] (Synthesis Example 7) Under a nitrogen stream, 12.2751 g of m-TB (0.05774 mol) and an amount of NMP such that the solids concentration after polymerization was 20 wt% were added to a 500 mL separable flask, and the mixture was stirred at room temperature to dissolve. Next, 27.7249 g of 26DHN-TME (0.05399 mol) was added, and the mixture was stirred at room temperature for one week to carry out a polymerization reaction, thereby preparing non-thermoplastic polyamic acid solution G. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution G was amine-terminated. The evaluation results of non-thermoplastic polyamic acid solution G and the resulting resin film are shown in Tables 1A and 1B.

[0208] (Synthesis Example 8) Under a nitrogen stream, 8.9735 g of m-TB (0.04221 mol) and an amount of NMP such that the solids concentration after polymerization was 15 wt% were added to a 500 mL separable flask, and the mixture was stirred at room temperature to dissolve. Next, 21.0265 g of 26DHN-TME (0.04094 mol) was added, and the mixture was stirred at room temperature for one week to carry out a polymerization reaction, thereby preparing non-thermoplastic polyamic acid solution H. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution H is amine-terminated. The evaluation results of non-thermoplastic polyamic acid solution H and the resulting resin film are shown in Tables 1A and 1B.

[0209] (Synthesis Example 9) Under a nitrogen stream, 8.7214 g of m-TB (0.04103 mol) and an amount of NMP such that the solids concentration after polymerization was 15 wt% were added to a 500 mL separable flask, and the mixture was stirred at room temperature to dissolve. Next, 21.2786 g of 26DHN-TME (0.04144 mol) was added, and the mixture was stirred at room temperature for one week to carry out a polymerization reaction, thereby preparing non-thermoplastic polyamic acid solution I. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution I was acid-terminated. The evaluation results of non-thermoplastic polyamic acid solution I and the resulting resin film are shown in Tables 1A and 1B.

[0210] Synthesis Example 10: Under a nitrogen stream, 8.8908 g of m-TB (0.04182 mol) and an amount of NMP such that the solids concentration after polymerization would be 15 wt % were added to a 500 mL separable flask and stirred at room temperature to dissolve. Next, 21.1092 g of BP-TME (0.03910 mol) was added, and the mixture was stirred at room temperature for one week to carry out a polymerization reaction, thereby preparing non-thermoplastic polyamic acid solution J. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution J was amine-terminated. Evaluation results of non-thermoplastic polyamic acid solution J and the resulting resin film are shown in Tables 1A and 1B.

[0211] (Synthesis Example 11) Under a nitrogen stream, 39.0813 g of DDA (0.07279 mol) was added to a 500 mL separable flask, 84 g of NMP, and 56 g of xylene were added so that the solids concentration after polymerization was 30 wt%, and the mixture was stirred at room temperature to dissolve. Next, 20.9187 g of BPDA (0.07097 mol) was added, and the mixture was stirred at room temperature for 3 hours to carry out a polymerization reaction, thereby preparing a solvent-soluble polyamic acid solution K. The solvent-soluble polyamic acid contained in the solvent-soluble polyamic acid solution K was amine-terminated. The evaluation results of the solvent-soluble polyamic acid solution K and the resulting resin film are shown in Tables 1A and 1B.

[0212] (Synthesis Example 12) Under a nitrogen stream, 4.2104 g of m-TB (0.01981 mol), 5.7962 g of TPE-R (0.01981 mol), and an amount of NMP such that the solids concentration after polymerization was 15 wt% were added to a 500 mL separable flask and stirred at room temperature to dissolve. Next, 19.9934 g of BP-TME (0.03704 mol) was added, and the polymerization reaction was continued with stirring at room temperature for one week to prepare non-thermoplastic polyamic acid solution L. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution L was amine-terminated. The evaluation results of non-thermoplastic polyamic acid solution L and the resulting resin film are shown in Tables 1A and 1B.

[0213] Synthesis Example 13: In a nitrogen stream, 50.0 g of elastomer resin and an amount of xylene to give a solids concentration of 30 wt% were added to a 300 mL separable flask, and the mixture was stirred to prepare an elastomer resin solution. The evaluation results of the obtained solution and resin film are shown in Tables 1A and 1B.

[0214] (Example 1) <Preparation of Resin Composition 1> As shown in Table 2A, 7.08 g of Solvent-Soluble Polyimide Solution A was mixed with 30.00 g of Non-Thermoplastic Polyamic Acid Solution G, and the mixture was diluted with 1.20 g of NMP and 11.72 g of xylene and stirred to prepare Resin Composition 1 (solid content 15%, viscosity 9725 cP).

[0215] <Preparation of Single-Sided Copper-Clad Laminate 1> Resin composition 1 was uniformly applied to copper foil 1 (electrolytic copper foil, thickness: 12 μm, roughness Rzjis of the resin side: 0.6 μm) so that the thickness after curing would be 25 μm, and then the coating was dried by heating at 100 to 120° C. for 10 minutes to remove the solvent. Further, heat treatment was carried out from room temperature to 320° C. at a temperature increase rate of 5° C. / min to complete imidization, and single-sided copper-clad laminate 1 was prepared.

[0216] <Preparation of Resin Film> The copper foil of single-sided copper-clad laminate 1 was etched away using an aqueous ferric chloride solution to obtain a resin film of Experiment No. 1. The various evaluation results of the resin film are shown in Table 2B.

[0217] (Experiment Nos. 2 to 20) Resin compositions, single-sided copper-clad laminates, and resin films were prepared using the compositions shown in Tables 2A and 4A, and various physical properties were measured in the same manner as in Example 1. The results are shown in Tables 2B, 3, and 4B.

[0218] Reference Example 1 A single-sided copper-clad laminate and a resin film were prepared and their physical properties were measured in the same manner as in Example 1, except that Solvent-Soluble Polyimide Solution B was used instead of Resin Composition 1. The results are shown in Table 1B (Sample No. 2).

[0219] Reference Example 2 A single-sided copper-clad laminate and a resin film were prepared and their physical properties were measured in the same manner as in Example 1, except that non-thermoplastic polyamic acid solution F was used instead of resin composition 1. The results are shown in Table 1B (Sample No. 6).

[0220]

[0221]

[0222]

[0223]

[0224]

[0225]

[0226]

[0227] Tables 2B and 4B confirm that Experiments 1 to 17, which contained the first resin and the second resin, or the (A2) component and the (B2) component, produced resin films with both a low CTE (50.0 ppm / K or less) and a low dielectric dissipation factor (0.0040 or less). Furthermore, in Experiments 1 to 17, the second resin or the (A2) component constituted the continuous phase. On the other hand, Table 1B indicates that Comparative Examples 1 and 2, which used a single polymer, were unable to achieve both a low CTE and a low dielectric dissipation factor. Furthermore, as shown in Table 3, Experiment 3, which had a low dielectric dissipation factor at 10 GHz, also exhibited sufficiently low values ​​at 28 GHz and 60 GHz, demonstrating that the resin composition according to this embodiment possesses excellent properties even at higher frequencies. As shown in Table 4B, Experiment 3 also exhibited a low dielectric dissipation factor at 10 GHz, but also exhibited sufficiently low values ​​at 28 GHz and 60 GHz, demonstrating that the resin composition according to this embodiment possesses excellent properties even at higher frequencies. In Nos. 18 to 20, the second resin or component (A2) did not constitute the continuous phase, and therefore the linear expansion coefficient exceeded 100.0 ppm / K.

[0228] Although the embodiments of the present invention have been described in detail above for the purpose of illustration, the present invention is not limited to the above-described embodiments and various modifications are possible.

[0229] The resin composition according to the embodiment has both a low CTE and a low dielectric loss tangent, and therefore has high industrial applicability.

Claims

1. A resin composition comprising: a first resin having a dielectric tangent of 0.0002 to 0.0020 at 10 GHz; and a second resin having a dielectric tangent of 0.0010 to 0.0040 at 10 GHz and a linear expansion coefficient of 1.0 to 40.0 ppm / K, wherein the second resin constitutes a continuous phase.

2. The resin composition according to claim 1, wherein the weight average molecular weight of the first resin is 120,000 or less.

3. SP value is 24.6 to 33.3 (J / cm 3 ) 1 / 2 and an SP value of 15.0 to 24.5 (J / cm 3 ) 1 / 2 and a component (B1) which is represented by the formula: wherein the component (A1) is a non-thermoplastic polyimide precursor, the component (B1) is a soluble compound having a structural unit which includes at least one of an aliphatic chain and an alicyclic skeleton, and the soluble compound is at least one of a soluble polyimide and a soluble polyimide precursor.

4. The resin composition according to claim 3, wherein the weight ratio (B1 / A1) of the component (B1) to the component (A1) is within the range of 15 / 85 to 83 / 17.

5. The resin composition according to claim 4, and a resin having an SP value of 10.3 to 19.5 (J / cm 3 ) 1 / 2 and an organic solvent with an SP value of 19.7 to 30.8 (J / cm 3 ) 1 / 2 and an organic solvent within the range of 6. A resin film containing a single or multiple polyimide layers, wherein at least one of the polyimide layers has an SP value of 24.6 to 33.3 (J / cm 3 ) 1 / 2 and an SP value of 15.0 to 24.5 (J / cm 3 ) 1 / 2 and a component (B2) which is a structural unit including an aliphatic chain or an alicyclic skeleton.

7. A resin film comprising a resin layer made of the resin composition according to claim 1.

8. The resin film according to claim 6 or 7, which has a dielectric loss tangent of 0.0030 or less at 10 GHz when measured with a split post dielectric resonator (SPDR) in an environment of a temperature of 24 to 26° C. and a relative humidity of 45 to 55%.

9. The resin film according to claim 8, which has a dielectric loss tangent of 0.0025 or less at 10 GHz.

10. A metal-clad laminate comprising an insulating resin layer consisting of a single layer or multiple layers, and a metal layer laminated on one or both sides of the insulating resin layer, wherein at least one of the insulating resin layers is constituted by the resin film according to claim 8.

11. A circuit board comprising an insulating resin layer consisting of a single layer or multiple layers, and a conductor circuit layer laminated on one side or both sides of said insulating resin layer, at least one of said insulating resin layers being constituted by the resin film according to claim 8.

12. An electronic device comprising the circuit board according to claim 11.

13. An electronic device comprising the circuit board according to claim 11.

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