Copolymer, resin base material, resin composition, coating liquid, polyimide, resin film, metal-clad laminate, circuit board, electronic device and electronic apparatus, and manufacturing method

Abstract

This copolymer includes: a first structure that includes two or more aromatic rings; and a second structure that has a chain structure in which carbon atoms are bonded to each other by single bonds. The number of carbon atoms constituting the chain structure is 6 or more. In the first structure, the distance between aromatic rings is 8.0 Å or less. The included quantity of the first structure is 15-85 mass%, and the included quantity of the second structure is 15-85 mass%.

Description

Copolymer, resin substrate, resin composition, coating liquid, polyimide, resin film, metal-clad laminate, circuit board, electronic device and electronic equipment, and manufacturing method

[0001] The present invention relates to a copolymer, a resin substrate, a resin composition, a coating liquid, a polyimide, a resin film, a metal-clad laminate, a circuit board, an electronic device, an electronic device, and a manufacturing method thereof, which are useful as materials for circuit boards, etc. This application claims priority based on Japanese Patent Application No. 2023-169699 filed in Japan on September 29, 2023, and Japanese Patent Application No. 2023-169700 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, typified by flexible printed circuits (FPCs). In recent years, efforts have been made to increase transmission frequencies in information processing and communication to transmit and process large amounts of information, and circuit boards are being required to reduce transmission loss by improving the dielectric properties of the insulating layer. It is expected that in the future, the insulating layers that make up FPCs will be increasingly required to be able to handle 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 or non-thermoplasticity, as well as their mechanical and electrical properties, vary significantly depending on their structural units. Generally, non-thermoplastic polyimides contain a large number of structural units with rigid chemical structures and are characterized by a high modulus of elasticity, a low 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.

[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 prior art related to polymer alloys, Patent Document 2 proposes a composition containing thermoplastic polyimide and polystyrene elastomer (thermoplastic). However, the film formed from the composition of Patent Document 2 has a low dielectric loss tangent, but a low tensile modulus and is prone to tack. Furthermore, a dielectric loss tangent lower than that of Patent Document 2 is required. Furthermore, Patent Document 3 proposes a composition containing polyimide and an amorphous resin. However, the film formed from the composition of Patent Document 3 has 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, P237, 238)

[0009] As mentioned above, attempts have been made to improve resin properties by using polymer alloy technology. However, when two or more types of polyimides with different structures and properties are alloyed, 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 copolymer, a resin composition, a coating liquid, and a polyimide that can form a resin film having an excellent tensile modulus and a low dielectric loss tangent using polymer alloy technology, a resin film, a metal-clad laminate, a circuit board, an electronic device, and an electronic equipment that contain the resin composition, and a method for producing the resin composition.

[0011] <1> A copolymer according to Aspect 1 of the present invention comprises: a first structure containing two or more aromatic rings; and a second structure having a chain structure in which carbon atoms are bonded to each other by single bonds, wherein the number of carbon atoms constituting the chain structure is 6 or more, the distance between the aromatic rings in the first structure is 8.0 Å or less, the content of the first structure is 15 to 85 mass %, and the content of the second structure is 15 to 85 mass %. <2> A resin substrate according to Aspect 2 of the present invention comprises the copolymer of Aspect 1. <3> A resin substrate according to Aspect 3 of the present invention is the resin substrate according to Aspect 2, wherein the first structure constitutes a continuous phase. <4> A resin composition according to Aspect 4 of the present invention comprises: a component (A1) that is a non-thermoplastic polyimide precursor; a component (B1) that is a soluble polyimide precursor having structural units containing at least one of an aliphatic chain and an alicyclic skeleton; and a first reactant in which the following are covalently bonded: <5> A resin composition according to Aspect 5 of the present invention comprises: a component (A1) that is a thermoplastic polyimide precursor; a component (B2) that is a soluble polyimide having structural units containing at least one of an aliphatic chain and an alicyclic skeleton; and a second reactant in which the above are covalently linked. <6> Aspect 6 of the present invention is the resin composition of Aspect 4, wherein the first reactant is formed by an amide bond between the component (A1) and the component (B1) at the polymer chain terminal. <7> Aspect 7 of the present invention is the resin composition of Aspect 5, wherein the second reactant is formed by an amide bond between the component (A1) and the component (B2) at the polymer chain terminal. <8> Aspect 8 of the present invention is the resin composition of Aspect 4 or 6, wherein the weight ratio (A1 / B1) of the component (A1) to the component (B1) is within the range of 15 / 85 to 85 / 15. <9> Aspect 9 of the present invention is the resin composition of Aspect 5 or Aspect 7, wherein the weight ratio (A1 / B2) of the component (A1) to the component (B2) is within the range of 15 / 85 to 85 / 15. <10> Aspect 10 of the present invention is a coating liquid comprising the resin composition of any one of Aspects 4 to 9 and a coating liquid having an SP value of 10.3 to 19.5 (J / cm ３ ) １／２ and a first organic solvent having an SP value of 19.7 to 30.8 (J / cm ３ ) １／２and a second organic solvent within the range. <11> A polyimide according to aspect 11 of the present invention comprises (A2) a first polyimide which is a non-thermoplastic polyimide, and (B2) a second polyimide which is a soluble polyimide having structural units including at least one of an aliphatic chain and an alicyclic skeleton. <12> A resin film according to aspect 12 of the present invention is a resin film comprising a single or multiple polyimide layers, wherein at least one of the polyimide layers comprises: a non-thermoplastic polyimide component (A2); and a soluble polyimide component (B2) which is a soluble polyimide having structural units including an aliphatic chain or an alicyclic skeleton, and wherein the components are covalently linked to each other. <13> A 13th aspect of the present invention is the resin film according to aspect 12, wherein the dielectric loss tangent at 10 GHz measured using a split post dielectric resonator (SPDR) at a temperature of 24 to 26°C and a relative humidity of 45 to 55% is 0.003 or less. <14> Aspect 14 of the present invention relates to the resin film of aspect 12 or 13, wherein the dielectric loss tangent at 10 GHz is 0.0022 or less. <15> Aspect 15 of the present invention relates to 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, wherein at least one of the insulating resin layers is composed of the resin substrate of aspect 2 or 3 or the resin film of any one of aspects 12 to 14. <16> Aspect 16 of the present invention relates to a circuit board comprising an insulating resin layer consisting of a single layer or multiple layers and conductor circuit layers laminated on one or both sides of the insulating resin layer, wherein at least one of the insulating resin layers is composed of the resin substrate of aspect 2 or 3 or the resin film of any one of aspects 12 to 14. <17> Aspect 17 of the present invention relates to an electronic device comprising the circuit board of aspect 16. <18> Aspect 18 of the present invention relates to an electronic device comprising the circuit board of aspect 16.<19> A method for producing a resin composition according to Aspect 19 of the present invention is a method for producing the resin composition according to Aspect 5, comprising: Step 1 of preparing a resin solution of the component (A1); Step 2 of preparing a resin solution of the component (B2); and Step 3 of mixing the resin solution of the component (A1) with the resin solution of the component (B2) to synthesize the second reactant. <20> Aspect 20 of the present invention is a method for producing a resin composition according to Aspect 19, wherein when the component (A1) has a reactive functional group, the component (B2) has a site that reacts with the functional group. <21> Aspect 21 of the present invention is a method for producing a resin composition according to Aspect 19 or Aspect 20, wherein the weight ratio (A1 / B2) of the component (A1) to the component (B2) mixed in Step 3 is within the range of 15 / 85 to 85 / 15. <22> A method for producing a resin composition according to Aspect 22 of the present invention is a method for producing the resin composition according to Aspect 5, comprising the steps of: Step 1 of preparing a resin solution of the component (B2), Step 2 of adding raw material monomers of the component (A1) to the resin solution of the component (B2) to prepare a mixed solution, and Step 3 of adding raw material monomers of the component (A1) to the mixed solution to synthesize the component (A1) and the second reactant. <23> Aspect 23 of the present invention is the method for producing a resin composition according to Aspect 22, wherein the weight ratio (total amount of A1 monomers / B2) of the total amount of raw material monomers of the component (A1) added in Steps 2 and 3 to the component (B2) is within a range of 15 / 85 to 85 / 15.

[0012] The copolymer, resin composition, and coating liquid of the above aspects of the present invention can form a resin film that can stably exhibit both an excellent tensile modulus and a low dielectric loss tangent. Therefore, the resin film and resin substrate using the copolymer or resin composition of the above aspects can be particularly preferably used as a circuit board material for FPCs and the like in electronic devices and electronic equipment requiring high-speed signal transmission, for example.

[0013] The polymer, resin substrate, resin composition, coating liquid, polyimide, resin film, metal-clad laminate, circuit board, electronic device and electronic equipment, and manufacturing method thereof according to embodiments of the present invention will be described below.

[0014] [First Embodiment] A copolymer according to a first embodiment includes a first structure including two or more aromatic rings and a second structure having a chain structure in which carbon atoms are bonded to each other by single bonds. Here, the copolymer refers to a polymer produced by polymerizing two or more types of substrates.

[0015] (First Structure) The first structure contains two or more aromatic rings. Here, the aromatic ring refers to a cyclic compound that satisfies Hückel's rule. Examples of aromatic rings include a benzene ring, a naphthalene ring, an anthracene ring, a pyrrole ring, a pyridine ring, and a thiophene ring. The aromatic ring is preferably composed only of carbon atoms and hydrogen atoms. Examples of such aromatic rings include a benzene ring or a condensed ring of two or more benzene rings (naphthalene, anthracene). When the first structure contains two or more aromatic rings, an ordered structure can be formed through intermolecular interactions such as π-π interactions when a resin substrate is formed from the copolymer, thereby improving the tensile modulus of the resin substrate and reducing the linear expansion coefficient. Furthermore, the formation of this ordered structure suppresses molecular motion and reduces the dielectric loss tangent of the resin substrate. The number of aromatic rings contained in the first structure is preferably three or more, more preferably five or more, and even more preferably ten or more. The number of aromatic rings may be 14 or more.

[0016] In the first structure, the distance between aromatic rings is 8.0 Å or less, preferably 7.0 Å or less, and more preferably 6.0 Å or less. The shorter the distance between aromatic rings, the easier it is to obtain the effect of intermolecular interactions and form an ordered structure. This reduces the linear expansion coefficient. The distance between aromatic rings is the total length of the bonds that minimizes the number of atoms in one or more bonds connecting the aromatic rings. When aromatic rings are bonded via COO, the total length of one C-C bond and two C-O bonds is the distance between the aromatic rings. The bond distance of each bond can be determined by measuring the interatomic distance in a stable state of a three-dimensional molecular structure drawn using known molecular drawing software on a computer. Examples of software used to draw molecular structures include Chem3D (CambridgeSoft) and Gaussian. The molecular structure in a stable state is a structure obtained by theoretically minimizing energy using known computational science methods, such as molecular mechanics, molecular dynamics, molecular orbital, density functional theory, quantum mechanics, etc., based on the structural formula. Alternatively, the bond distance of each bond can be calculated from known literature values.

[0017] The first structure may have, for example, a structure represented by the following formula (1) or a structure represented by the following formula (2). １ is a single bond (i.e., a bond in which a carbon atom constituting an aromatic ring is directly bonded to a carbon atom constituting another aromatic ring), a divalent linking group, or a structure represented by the following formula (3): * in the following formula (1) represents a bond.

[0018] Y １ The divalent linking group is not particularly limited as long as the distance between the aromatic rings is 8.0 Å or less. ２ -, -CH ２ -CH ２ -, -CH ２ -CH ２ -CH ２ -, -CH(CH ３ ) -, -C(CH ３ ) ２ -, -C(CF３ ) ２ -, -CF ２ -, -COO-, -OOC-, -SO-, -SO ２ -, -S-, -CO-, -CONH- and the like.

[0019]

[0020] Y in the following formula (2) ２ represents a single bond, a divalent linking group, or a structure represented by the following formula (3). * in the following formula (2) represents a bond. Y ２ The divalent linking group Y is not particularly limited as long as the distance between the aromatic rings is 8.0 Å or less. ２ The divalent linking group is Y １ The same can be used.

[0021] Ar in the following formula (2) １ is a divalent aromatic ring group or a divalent aromatic imide ring-containing group having a structure in which a cyclic imide group is condensed with an aromatic ring. １ The aromatic ring contained in may have a substituent.

[0022] Ar in the following formula (2) ２ is a divalent aromatic ring group or a divalent aromatic imide ring-containing group having a structure in which a cyclic imide group is condensed with an aromatic ring. ２ The aromatic ring contained in Ar may have a substituent. １ and Ar ２ may be the same or different.

[0023] The substituent on the aromatic ring in the following formula (2) is, for example, a hydrogen atom (i.e., no substituent), an alkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, a phenyl group, a hydroxy group, or a carboxyl group. The substituent is preferably, for example, an alkyl group having 1 to 3 carbon atoms. The position of the substituent on the aromatic ring is not particularly limited.

[0024] In the following formula (3), X １ and X ２ represents a divalent linking group or a single bond. １ and X ２ The linking group is —O—, —CH ２-, -CH ２ -CH ２ -, -CH ２ -CH ２ -CH ２ -, -CH(CH ３ ) -, -C(CH ３ ) ２ -, -C(CF ３ ) ２ -, -CF ２ -, -COO-, -OOC-, -SO-, -SO ２ -, -S-, -CO-, -CONH-, etc. １ and X ２ may be the same or different. In the following formula (3), A represents a divalent group containing an aromatic ring such as a benzene ring or a naphthalene ring. The benzene ring and the naphthalene ring may have any substituent. Examples of the substituent include an alkyl group and an alkoxy group, and a methyl group and an ethyl group are preferred. The number of substituents is preferably 0 to 2.

[0025]

[0026]

[0027] Specific examples of the first structure include repeating units constituting polymers such as 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), and polyarylate (PAR), and structures composed of combinations thereof.

[0028] "Method of Determining First Structure" In the copolymer of the first embodiment, the first structure may contain two or more aromatic rings, and the distance between the aromatic rings may be 8.0 Å or less. For example, a structure represented by the above formula (A1) and a structure represented by the above formula (A2) may be mixed. Furthermore, if an aromatic ring (aromatic ring A) is present at the end of the bond represented by the above formula (A1), and the distance between the aromatic ring in the above formula (A1) and the aromatic ring A is 8.0 Å or less, the aromatic ring A is also included in the first structure. If the distance between the aromatic ring (aromatic ring B) included in the first structure and the next aromatic ring exceeds 8.0 Å, the aromatic ring B becomes the terminal of the first structure. In other words, both ends of the first structure are aromatic rings. Here, when the aromatic ring has a ring structure sharing one side of the aromatic ring as in the above formula (1), the ring structure sharing one side of the aromatic ring is also considered to be part of the first structure (here, a cyclic imide moiety). When the structure of the repeating unit is clear, the repeating unit may be regarded as the first structure. When the ratio of the monomers used in synthesizing each copolymer is clear, the first structure may be calculated from the blending amount of each monomer.

[0029] In the copolymer according to the first embodiment, the content of the first structure is 15 to 85% by mass relative to the total mass of the copolymer. The content of the first structure is preferably 25% by mass or more. The content of the first structure is more preferably 40% by mass or more. The content of the first structure is preferably 90% by mass or less. The content of the first structure is more preferably 75% by mass or less, and even more preferably 65% ​​by mass or less. In the copolymer according to the first embodiment, the content of the first structure is 15 to 85% by mass, so that when molded into a resin substrate, the formation of an ordered structure can be promoted, the linear expansion coefficient of the copolymer can be further reduced, and the dielectric loss tangent can be lowered.

[0030] (Second Structure) The second structure according to the first embodiment has a chain structure in which carbon atoms are bonded to each other by single bonds. The number of carbon atoms constituting the chain structure of the second structure (first chain structure) is 6 or more. The chain structure of the second structure may be a straight chain structure in which carbon atoms are linked in a row, or may be a branched molecular chain or a cyclic structure in which carbon atoms are branched.

[0031] The number of carbon atoms constituting the first chain structure is preferably 6 or more, more preferably 10 or more, and even more preferably 20 or more. By increasing the number of carbon atoms constituting the first chain structure, the dielectric loss tangent can be reduced.

[0032] The carbon atoms constituting the first chain structure are preferably bonded to a hydrogen atom or a fluorine atom in addition to the carbon atom. ２ - and -CF ２ At least one of the above may be used as a repeating structural unit.

[0033] The first chain structure may have a side chain. Here, the side chain refers to a branch extending from the first chain structure and having a length of about an oligomer. Examples of the side chain include an aryl group such as a phenyl group, a maleimide group, an allyl group, and a phosphate group.

[0034] The second structure can be, for example, a repeating unit containing an aliphatic chain or an alicyclic skeleton that constitutes polyimide, polyamide, maleimide, polyolefin (polyethylene, polypropylene, etc.), polyester, polyurethane, polystyrene, polystyrene elastomer, cycloolefin polymer (COP), polymethylpentene (PMP), or cycloolefin copolymer (COC), or a structure formed from a combination of these repeating units.

[0035] When the carbon atom (carbon atom A) of the first chain structure is bonded to an atom other than a carbon atom, or when the carbon atom A is bonded to an aromatic ring, the carbon atom A is considered to be the terminal carbon atom of the second structure. Here, if there is a structure between the first structure and the second structure that has a molecular weight of 100 or less and is not included in the first structure, the structure is considered to be part of the second structure. Note that when the structure of the repeating unit is clear, the repeating unit may be considered to be the second structure.

[0036] The content of the second structure is 15 to 85% by mass relative to the total mass of the copolymer according to the first embodiment. The content of the second structure is preferably 20% by mass or more. The content of the second structure is more preferably 40% by mass or more. The content of the second structure is preferably 75% by mass or less. The content of the second structure is more preferably 65% ​​by mass or less. In the copolymer according to the first embodiment, when the content of the second structure is 15 to 85% by mass, an ordered structure capable of reducing the dielectric loss tangent is more easily obtained.

[0037] (Other Structures) The copolymer according to the first embodiment may contain a structure other than the first structure and the second structure. The other structure is not particularly limited as long as it does not adversely affect the linear expansion coefficient and the dielectric loss tangent. For example, it may be a chain structure formed of a siloxane bond (Si—O—Si).

[0038] The content of the other structures relative to the total mass of the copolymer according to the first embodiment is, for example, 0% by mass to 30% by mass. Since the other structures may be absent, the lower limit is 0%.

[0039] (Mass ratio of first structure and second structure) The first structure and the second structure can be determined by identifying the chemical structure of the copolymer by a known method. For example, if the copolymer is soluble, the identification can be performed by nuclear magnetic resonance analysis ( 1 H-NMR, 13 Analysis can be performed using techniques such as C-NMR. After identifying the chemical structure of the copolymer, the resulting structure is identified as a first structure and a second structure according to the above criteria. The portions not assigned to the first and second structures are designated as other structures, and the mass proportion of each structure can be determined by calculating the molecular weight of each structure. If the copolymer is insoluble, it may be decomposed to the monomer level and the mass proportion of each structure calculated by determining the ratio of the monomers.

[0040] The weight-average molecular weight of the copolymer is preferably 500,000 or less. The weight-average molecular weight of the copolymer is preferably 300,000 or less. The weight-average molecular weight of the copolymer is more preferably 250,000 or less. When the weight-average molecular weight of the copolymer is small, the phase separation state of the resin composition changes, and it is easy to form a uniform phase. Furthermore, in the case of a coating liquid, it becomes easy to adjust the viscosity.

[0041] The number average molecular weight of the copolymer is preferably 250,000 or less. The number average molecular weight of the copolymer is preferably 200,000 or less. The number average molecular weight of the copolymer is more preferably 100,000 or less. If the number average molecular weight of the copolymer is small, the phase separation state of the resin composition changes, and it is likely to become a uniform phase.

[0042] "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).

[0043] The copolymer according to the first embodiment can be obtained by selecting a substrate (monomer) so as to have the above-mentioned first structure and second structure and polymerizing it by a known method.

[0044] (Resin Composition) The resin composition according to the first embodiment contains the copolymer according to the first embodiment.

[0045] "Optional Components" In addition to the copolymer, the resin composition according to the first embodiment may further contain optional components, such as organic fillers, inorganic fillers, cyclization agents, curing agents, curing accelerators, plasticizers, elastomers, coupling agents, pigments, flame retardants, and heat dissipation agents, 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 second structure and the first structure may be added within the scope of the invention.

[0046] "Phase Structure" In the resin composition according to the first embodiment, the first structure constitutes a continuous phase (continuous structure). Here, the term "the first structure constitutes a continuous phase" means that the regions in which the first structure 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 first structure constitutes a continuous phase. The resin composition may be a homogeneous phase (homogeneous compatible structure) in which the second structure and the first structure are compatible with each other, or may be a phase-separated structure such as a sea-island structure or an interconnected structure. Here, a structure is determined to have a homogeneous compatible structure if there are no regions (e.g., island phases) with a circle-equivalent diameter of 500 nm or more in a 5 μm × 5 μm area observed using a scanning electron microscope, and a phase-separated structure if there are regions with a circle-equivalent diameter of 500 nm or more. 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 first structure is 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.

[0047] When the phase-separated structure of the resin composition according to the first embodiment is an island-sea structure, the island phases preferably include the second structure. The average equivalent circle diameter of the island phases is preferably 0.001 μm to 20 μm. When the average equivalent circle diameter of the island phases is 0.010 μm to 10 μm, the linear expansion coefficient can be 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.

[0048] 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.

[0049] 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.

[0050] "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.

[0051] 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 considered to be the second structure, and the light colored portion is considered to be the first structure. The composition and ratio of each resin are preferably confirmed using microscopic Raman analysis, energy dispersive electron X-ray spectroscopy (EDX), or the like. Image analysis is performed using various analysis software (e.g., 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 of 500 nm or more per unit area are calculated (calculating the number of islands of 500 nm or more 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.

[0052] The determination of the region where the first structure 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 first structure is higher than the proportion of the second structure is determined to be the region where the first structure is present.

[0053] If the region in the SEM image in which the first structure exists is continuously connected from one end of the image to the other end, it is determined that the first structure constitutes a continuous phase.

[0054] When the phase structure of the resin composition according to the first embodiment is a homogeneous compatible structure, if the presence of the first structure can be confirmed by microscopic Raman or the like, the entire homogeneous phase is determined to be the region where the first structure is present. In this case, it is determined that the first structure constitutes a continuous phase.

[0055] 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.

[0056] <Resin substrate> The resin substrate according to the first embodiment includes the copolymer according to the first embodiment. The resin substrate according to the first embodiment may be formed from the resin composition according to the first embodiment. The shape of the resin substrate is not particularly limited. The shape of the resin substrate is, for example, a film, a plate, or a layer. Hereinafter, a more detailed description will be given using a film-shaped substrate film as an example.

[0057] <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 copolymer. 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 a layer made of the resin composition according to the first embodiment, and therefore has excellent tensile modulus and high-frequency characteristics.

[0058] 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.

[0059] 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, glass plate, polyimide film, polyamide film, or polyester film.

[0060] 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.

[0061] "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.

[0062] "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-Tech Technology 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.

[0063] "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.

[0064] "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 first embodiment preferably has a dielectric dissipation factor (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. This dielectric dissipation factor (Tan δ) is preferably 0.0030 or less, more preferably 0.0025 or less, and most preferably 0.0023 or less. If the dielectric dissipation factor exceeds 0.0030, 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 of the resin film according to the first embodiment can be measured using the method described above.

[0065] The dielectric constant and dielectric loss tangent can be evaluated by the following method. A resin composition is molded into a film to obtain a resin 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%.

[0066] "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 × 10 ５ Pa or more, and ６ Pa or more, and more preferably 1.0 × 10６ Pa ~ 5.0 x 10 ９ It 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.

[0067] "Glass transition temperature" When the resin film according to the first embodiment is amorphous and has no melting point, the glass transition temperature (Tg) is preferably 180° C. or higher, and more preferably in the range of 180 to 400° C. When the Tg of the resin film is 180° C. or higher, heat resistance that enables use in mounting and in high-temperature environments can be achieved.

[0068] 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 x 20 mm 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 the 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'.

[0069] "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.

[0070] The melting point of the resin can be measured, for example, by a method in accordance with JIS K7121: 2012. When multiple peaks due to melting appear, the highest peak temperature is taken as the melting point.

[0071] (Tensile Modulus of Elasticity) The resin film according to the first embodiment has a tensile modulus of elasticity of 1.0 GPa or more. The tensile modulus of elasticity of the resin film according to the first embodiment is preferably in the range of 1.5 to 6.0 GPa, and more preferably in the range of 1.5 GPa to 5.0 GPa. If the tensile modulus of elasticity is less than 1.0 GPa, tack occurs, making it impossible to obtain a film that is easy to process.

[0072] (Elongation) The resin film according to the first embodiment preferably has an elongation of 1% or more, more preferably 5% or more. If the elongation is less than 1%, the toughness will be deteriorated.

[0073] 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.

[0074] 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.

[0075] <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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] <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.

[0080] <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.

[0081] The above has described the resin composition, coating liquid, resin film, metal-clad laminate, circuit board, electronic device, and electronic equipment according to the first embodiment. The copolymer of the first embodiment includes a first structure containing two or more aromatic rings and a second structure having a chain structure in which carbon atoms are bonded to each other by single bonds, the number of carbon atoms constituting the chain structure being 6 or more, the distance between the aromatic rings in the first structure being 8.0 Å or less, the content of the first structure being 15 to 85 mass%, and the content of the second structure being 15 to 85 mass%, so that the copolymer is likely to have an excellent tensile modulus, a low CTE, and a low dielectric loss tangent.

[0082] [Second Embodiment] (Resin Composition) A first resin composition according to a second embodiment of the present invention contains a first reactant (component (R1)) in which component (A1), which is a non-thermoplastic polyimide precursor, and component (B1), which is a soluble polyimide precursor having a structural unit containing at least one of an aliphatic chain and an alicyclic skeleton, are covalently linked.

[0083] The second resin composition according to the second embodiment contains a second reactant (component (R2)) in which a component (A1) that is a thermoplastic polyimide precursor and a component (B2) that is a soluble polyimide having a structural unit containing at least one of an aliphatic chain and an alicyclic skeleton are covalently linked.

[0084] The resin composition according to the second embodiment may contain both the (B1) component and the (B2) component, or both the (R1) component and the (R2) component.

[0085] 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 the present invention, 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.

[0086] <Component (A1)> The 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 the present invention, a polyimide having a storage modulus of 1.0 × 10 at 30°C measured using a dynamic mechanical analyzer (DMA) is used. ９ Pa or more, and the storage modulus in the temperature range within the glass transition temperature + 30°C is 1.0 × 10 ８ 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 the present invention, 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 ８ This refers to polyimides that exhibit a modulus of less than Pa.

[0087] (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. When the weight-average molecular weight of the non-thermoplastic polyimide precursor of component (A1) is in the range of 5,000 to 300,000, the reactivity of the terminal groups is less likely to deteriorate due to steric hindrance, and the reaction with component B1 or B2 is more likely to proceed. If the weight-average molecular weight is less than 5,000, film properties are impaired and low CTE characteristics cannot be achieved. Furthermore, the increase in terminal functional groups leads to a deterioration in the dielectric loss tangent. On the other hand, if the weight-average molecular weight exceeds 300,000, steric hindrance becomes so great that the reaction from the terminal groups becomes more difficult to proceed. Furthermore, the concentration of terminal groups decreases during the reaction with component B1 or B2, resulting in a slower reaction rate. Furthermore, the viscosity increases excessively, making the film insoluble in solvents. The weight-average molecular weight of the non-thermoplastic polyimide of component (A2), which will be described later, is the same as that of component (A1). The weight-average molecular weight can be measured by the method described above.

[0088] (Number Average Molecular Weight) The weight average molecular weight of the non-thermoplastic polyimide precursor of component (A1) is, for example, preferably in the range of 2,000 to 150,000, more preferably in the range of 3,000 to 100,000, and most preferably in the range of 5,000 to 80,000. When the number average molecular weight of the non-thermoplastic polyimide precursor of component (A1) is in the range of 2,000 to 150,000, the reactivity of the terminal groups is less likely to deteriorate due to steric hindrance, and the reaction with component B1 or B2 is more likely to proceed.

[0089] (Glass Transition Temperature) The non-thermoplastic polyimide precursor of component (A1) preferably has a glass transition temperature (Tg) of 180° C. or higher after imidization, and more preferably in the range of 200 to 450° C. 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 the heat resistance sufficient for use in packaging or in high-temperature environments will not be obtained.

[0090] The storage modulus and glass transition temperature of the resin to be evaluated can be measured by the following method. A film or resin sheet is cut into a size of 5 mm x 20 mm 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'.

[0091] (CTE) The non-thermoplastic polyimide precursor of component (A1) preferably has a CTE (coefficient of linear expansion) of 50 ppm / K or less, and more preferably in the range of 5 to 30 ppm / K, when the non-thermoplastic polyimide is formed into a film after imidization. If the CTE exceeds 50 ppm / K, dimensional stability is impaired when the non-thermoplastic polyimide is applied to a resin film or a metal-clad laminate.

[0092] "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-Tech Technology 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.

[0093] (Elongation) The non-thermoplastic polyimide precursor of component (A1) preferably has an elongation of 0.1% or more, more preferably 0.5% or more and 150% or less, when the non-thermoplastic polyimide after imidization is formed into a film. A more preferable elongation is 100% or less, because if the elongation is high, the CTE of the resin film will be deteriorated. The elongation can be measured by the method shown in the examples below.

[0094] 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.

[0095] 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.

[0096] The non-thermoplastic polyimide precursor of component (A1) contains a tetracarboxylic acid residue and a diamine residue. In the present invention, 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.

[0097] (Tetracarboxylic Acid Residue) The tetracarboxylic acid used in the non-thermoplastic polyimide precursor of component (A1) can be used without any 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 (4), which are expected to enhance the linearity of polyimide molecular chains and result in an improved tensile modulus and 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 the present invention, the tetracarboxylic acid dianhydride residue derived from the tetracarboxylic acid dianhydride represented by general formula (4) may be referred to as "acid dianhydride residue (1)."

[0098]

[0099] In general formula (4), Ar represents a divalent group containing one or more aromatic rings, and is preferably a divalent group selected from the following formulae:

[0100]

[0101] 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).

[0102] The compound represented by general formula (4) is an ester group-containing acid dianhydride, and despite its relatively large molecular weight, which allows for a reduced imide group concentration, it has the effect of suppressing the 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 biphenyl and naphthalene skeletons are rigid, which facilitates the formation of an ordered structure, making this 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.

[0103] Examples of the tetracarboxylic dianhydride represented by the general formula (4) 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.

[0104] Furthermore, tetracarboxylic acid residues having a biphenyl skeleton or a naphthalene skeleton have high planarity and linearity, which promotes in-plane orientation by improving the linearity of polyimide molecular chains, thereby improving the tensile modulus and CTE. Furthermore, they contribute to the stacking of molecular chains, which facilitates the formation of an ordered structure, and suppresses molecular motion, thereby improving the dielectric loss tangent.

[0105] 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 40 to 100 mol %, based on the total tetracarboxylic dianhydride residues of component (A1). 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.

[0106] 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 40 to 100 mol %, based on the total tetracarboxylic acid dianhydride residues.

[0107] (Diamine Component) The non-thermoplastic polyimide precursor of component (A1) can be any diamine compound generally used in non-thermoplastic polyimide precursors, without any restrictions. 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 (5) 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 the present invention, the diamine residue derived from the diamine compound represented by general formula (5) may be referred to as "diamine residue (2)".

[0108]

[0109] [In formula (5), 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.]

[0110] The diamine compound represented by general formula (5) 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.

[0111] Preferred examples of the diamine compound represented by general formula (5) 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.

[0112] The content of diamine residue (2) in the non-thermoplastic polyimide precursor of component (A1) is preferably 30 mol% or more, more preferably 40 mol% or more, and most preferably in the range of 50 to 100 mol%, based on the total diamine residues of component (A1). 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%.

[0113] 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 (constituent units). When the non-thermoplastic polyimide precursor of component (A1) contains two or more structural units, the structural units may be present as blocks or randomly, but are preferably present randomly.

[0114] 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.

[0115] 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 %.

[0116] 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.

[0117] <Component (B1) and Component (B2)> Component (B1) is a soluble polyimide precursor having structural units containing at least one of an aliphatic chain and an alicyclic skeleton, and component (B2) is a soluble polyimide having structural units containing at least one of an aliphatic chain and an alicyclic skeleton. Component (B2) is a solvent-soluble thermoplastic polyimide, and its precursor is component (B1). That is, the soluble polyimide of component (B2) is obtained by imidizing a polyimide precursor (polyamic acid) of component (B1) obtained by reacting a tetracarboxylic acid anhydride component with a diamine component. The soluble polyimide of component (B2) has structural units containing an aliphatic chain or an alicyclic skeleton, which enables the resin film to have a low dielectric loss tangent.

[0118] From the viewpoint of sufficiently lowering the dielectric loss tangent, the components (B1) and (B2) preferably contain 20% by weight or more, and more preferably 30 to 70% by weight, of structural units containing an aliphatic chain or an alicyclic skeleton in the polymer chain. If the content of structural units containing an aliphatic chain or an alicyclic skeleton is less than 20% by weight, it becomes difficult to achieve a low dielectric loss tangent when a resin film is formed.

[0119] The structural unit containing an aliphatic chain or an alicyclic skeleton may be derived from a tetracarboxylic acid anhydride component or a diamine component. Component (B1) and component (B2) preferably have an aliphatic chain containing 10 or more carbon atoms, and more preferably have an aliphatic chain containing 10 to 54 carbon atoms. If the aliphatic chain does not contain 10 or more carbon atoms, the imide group concentration increases, which may result in a deterioration in the dielectric loss tangent when formed into a film.

[0120] (Weight-Average Molecular Weight) The weight-average molecular weight of components (B1) and (B2) is preferably in the range of 5,000 to 150,000, more preferably 10,000 to 150,000. If the weight-average molecular weight of components (B1) and (B2) is less than 5,000, the toughness cannot be fully achieved. Furthermore, the dielectric loss tangent deteriorates due to an increase in the concentration of terminal functional groups. On the other hand, if the weight-average molecular weight exceeds 150,000, steric hindrance increases, making it difficult for the reaction to proceed from the terminal groups. Furthermore, the decrease in the concentration of terminal groups during alloying reduces the reaction rate. Furthermore, the viscosity increases excessively, making the product insoluble in solvents. The weight-average molecular weight can be measured by the method described above.

[0121] (Number Average Molecular Weight) The number average molecular weight of components (B1) and (B2) is preferably in the range of 2,000 to 100,000, more preferably 4,000 to 70,000. If the number average molecular weight of components (B1) and (B2) is less than 2,000, the toughness cannot be fully exhibited. Furthermore, the dielectric loss tangent deteriorates due to an increase in the concentration of terminal functional groups. On the other hand, if the number average molecular weight exceeds 100,000, steric hindrance increases, making it difficult for the reaction to proceed from the terminal groups. Furthermore, the decrease in the concentration of terminal groups during alloying reduces the reaction rate. Furthermore, the viscosity increases excessively, making the product insoluble in solvents. The number average molecular weight can be measured by the method described above.

[0122] (Dielectric Dissipation Factor) When the soluble polyimide of component (B2) is formed into a film by itself, the dielectric dissipation factor (Df) at 10 GHz after 24 hours of conditioning under conditions of a temperature of 24 to 26°C and a humidity of 45 to 55% is preferably 0.0022 or less, more preferably 0.0020 or less. If the dielectric dissipation factor exceeds 0.0022, the dielectric dissipation factor after alloying will be insufficient. The dielectric dissipation factor of component (B2) may be 0.0002 or more.

[0123] The dielectric constant and dielectric loss tangent of a resin 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%.

[0124] (Tensile Modulus) The soluble polyimide of component (B2) 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. The tensile modulus can be measured by the method described above.

[0125] The tetracarboxylic acid anhydride component and the diamine component used as raw materials for the components (B1) and (B2) will be described below by giving preferred specific examples.

[0126] (Tetracarboxylic Acid Anhydride Component) For the components (B1) and (B2), 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 formula (6) and / or (7). For example, it is preferable to use raw materials for the components (B1) and (B2) that contain tetracarboxylic acid anhydrides represented by the following general formula (6) and / or (7) 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 components (B1) and (B2) to contain tetracarboxylic acid residues derived from tetracarboxylic acid anhydrides represented by the following general formula (6) and / or (7) 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 formula (6) and / or (7) 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 components (B1) and (B2). If the total amount of tetracarboxylic acid residues derived from the tetracarboxylic acid anhydrides represented by the following general formula (6) and / or (7) is less than 90 mol %, the solvent solubility of the soluble polyimide of component (B2) tends to decrease.

[0127]

[0128] In general formula (6), X represents a single bond or a divalent group selected from the following formulae, and in general formula (7), 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 (6) 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 (7) 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] The components (B1) and (B2) may contain, in addition to the tetracarboxylic acid anhydrides represented by the general formulas (6) and (7), 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) For the components (B1) and (B2), diamine compounds commonly used in the synthesis of thermoplastic polyimides can be used as raw materials. However, from the viewpoint of lowering the dielectric dissipation factor and improving the dielectric properties, it is preferable to use diamine components 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% relative to the total diamine components of the components (B1) and (B2). In other words, the 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% relative to 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 the present invention, dimer acids that have been further subjected to a hydrogenation reaction to reduce the degree of unsaturation are also included in the definition of 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, Ltd.) and PRIAMINE 1073 (trade name), PRIAMINE 1074 (trade name), and PRIAMINE 1075 (trade name) manufactured by Croda Japan.

[0138] The components (B1) and (B2) may contain diamine residues derived from diamine compounds generally used as raw materials for polyimides, provided that the effects of the invention are not impaired.

[0139] In the components (B1) and (B2), 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, in the components (B1) and (B2), when a plurality of polyimide structural units are present, they may be present as blocks or randomly, but are preferably present randomly.

[0140] The soluble polyimide (B2) can be produced by reacting the tetracarboxylic anhydride and diamine components in a solvent to produce the polyimide precursor (polyamic acid) (B1), followed by heating and ring-closure. For example, the polyimide precursor (B1) can be obtained by dissolving the tetracarboxylic anhydride and diamine components 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 polyimide precursor (B1) obtained by the polymerization reaction is about 5 to 50 wt %.

[0141] The synthesized polyimide precursor of component (B1) generally has excellent solvent solubility, so it is advantageous to use it as a reaction solvent solution, but it can be concentrated, diluted, or replaced with another organic solvent if necessary. The viscosity of the solution of the polyimide precursor of component (B1) is preferably within the range of 20 cP to 100,000 cP. As will be described later, the synthesis of component (B1) in this specification can also be carried out in the presence of component (A1).

[0142] The method for imidizing the polyimide precursor of component (B1) to form the soluble polyimide of component (B2) 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 (B2) 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 The imidization rate 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. The calibration curve can be prepared based on the data of a sample whose imidization rate is known.

[0144] <Component (R1) and Component (R2)> Component (R1) is a reaction product of component (A1) and component (B1), formed by a covalent bond between a reactive functional group of component (A1) and a reactive functional group of component (B1). The terminal functional groups of component (A1) and component (B1) may be linked via an amide bond. Specifically, component (R1) has a block structure in which the acid terminal of the soluble polyimide precursor of component (B1) is linked to the amine terminal of the non-thermoplastic polyimide precursor of component (A1), or the amine terminal of the soluble polyimide precursor of component (B1) is linked to the acid terminal of the non-thermoplastic polyimide precursor of component (A1). This block structure contributes to a low dielectric loss tangent, excellent tensile modulus, and low CTE when formed into a film. The block structure may be repeated multiple times. 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 a polymer chain, and the term "amine terminal" refers to a state in which an amino group is present at the end of a polymer chain.

[0145] Component (R2) is a reaction product of component (A1) and component (B2), and is formed by a covalent bond between a reactive functional group of component (A1) and a reactive functional group of component (B2). The reactive functional groups of component (A1) and component (B2) may be linked via an amide bond. Specifically, component (R2) has either a block structure in which the acid end of the soluble polyimide of component (B2) is linked to the amine end of the non-thermoplastic polyimide precursor of component (A1), or a block structure in which the amine end of the soluble polyimide of component (B2) is linked to the acid end of the non-thermoplastic polyimide precursor of component (A1). This block structure contributes to a low dielectric loss tangent, excellent tensile modulus, and low CTE when formed into a film. The block structure may be repeated multiple times.

[0146] The (R1) component and the (R2) component are reactants linked by a covalent bond. Examples of the covalent bond include a single bond (carbon-carbon), an amide bond, an ester bond, an imide bond, an ether bond, and a sulfide bond. In addition to the examples given here, general covalent bonds may also be included.

[0147] When component (B1) or (B2) is produced by a synthetic reaction from raw material monomers in the presence of component (A1), the synthetic reaction from the raw material monomers to component (B1) or (B2) is presumed to proceed preferentially and predominantly over the addition polymerization reaction of the raw material monomer to component (A1), and therefore, it is believed that component (B1) or (B2) is produced first, and then a terminal functional group of the resulting component (B1) or (B2) reacts with a terminal functional group of component (A1). When component (A1) is produced by a synthetic reaction from raw material monomers in the presence of component (B1) or (B2), the synthetic reaction from the raw material monomers to component (A1) is presumed to proceed preferentially and predominantly over the addition polymerization reaction of the raw material monomer to component (B1) or (B2), and therefore, it is believed that component (A1) is produced first, and then a terminal functional group of the resulting component (A1) reacts with a terminal functional group of component (B1) or (B2).

[0148] "Weight-Average Molecular Weight" The weight-average molecular weight (MW) of the reactants (R1) and (R2), determined from the main peak with an area ratio of 50% or more in gel permeation chromatography (GPC), is preferably in the range of 10,000 to 1,000,000, more preferably 20,000 to 500,000, and most preferably 20,000 to 300,000. If the MW of components (R1) and (R2) is less than 10,000, film properties are impaired and low CTE characteristics cannot be achieved. Furthermore, the increase in terminal functional groups leads to a deterioration in dielectric loss tangent. On the other hand, if the MW of the non-thermoplastic polyimide precursor (A1) exceeds 1,000,000, the viscosity increases excessively, rendering the product insoluble in solvents. MW can be measured using the method described above.

[0149] [Composition Ratio] The weight ratio (A1 / B1 or A1 / B2) of the (A1) component to the (B1) component or the (B2) component in the resin composition is preferably in the range of 15 / 85 to 85 / 15, more preferably in the range of 20 / 80 to 80 / 20, even more preferably in the range of 35 / 65 to 65 / 35, and most preferably 40 / 60 to 60 / 40, from the viewpoint of realizing a low dielectric loss tangent and a low CTE. If the weight ratio (A1 / B1 or A1 / B2) 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 realized, and if it exceeds 85 / 15, the effect of lowering the dielectric loss tangent of the resin film may not be fully realized.

[0150] In addition, the weight ratio of component (R1) to the total of components (A1), (B1), and (R1) in the resin composition [R1 / (A1+B1+R1)], or the weight ratio of component (R2) to the total of components (A1), (B2), and (R2) [R2 / (A1+B2+R2)], is preferably 0.2 or more, more preferably 0.4 or more, and most preferably 0.6 or more. If the weight ratio is less than 0.2, the presence of unreacted components (A1) and (B1) or (B2) increases the terminal groups of each component, resulting in increased polarity and a deterioration in the dielectric loss tangent.

[0151] In order to fully achieve the effects of the present invention, the total amount of components (A1), (B1), and (R1), or the total amount of components (A1), (B2), and (R2) in the resin composition may be more than 25% 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 solids content. Here, the solids content refers to the remainder after removing the solvent from the resin composition.

[0152] [Optional Components] The resin composition of the present invention 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, without impairing the effects 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.

[0153] <Coating Liquid> Furthermore, the coating liquid according to the second embodiment can contain the resin composition according to the second embodiment and a solvent such as an organic solvent. Since the components (A1), (B1), (B2), (R1), and (R2) are all solvent-soluble and exhibit good solubility, the resin composition according to the second embodiment can be prepared as a polyimide 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, 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.

[0154] Preferred examples of the organic solvent used in the coating liquid according to the second embodiment include the following combinations of the first and second solvents.

[0155] 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 component (B1). It is preferable that the component (B1) 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 / cm ３ ) 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.

[0156] Second solvent (component (D)): SP value (solubility parameter) of 9.6 to 15 (cal / cm ３ ) １／２ (19.7~30.8 (J / cm３ ) １／２ The second solvent is a highly polar solvent, and its use makes it easy to prepare a varnish using the component (A1). It is preferable that the component (A1) is easily soluble in the second solvent. Examples of organic solvents 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.

[0157] 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 conditions, the components (A1) and (B1) can be easily mixed together. When two or more first and second solvents are used in combination, 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.

[0158] The weight ratio of the first solvent to the second solvent (first solvent / second solvent) in the coating liquid 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).

[0159] The total content of the solvents is not particularly limited, but it is preferable to adjust the total concentration of the component (A1), the component (B1) or (B2), and the component (R1) or (R2) to about 5 to 30% by weight based on the entire coating liquid.

[0160] [Viscosity] The viscosity of the coating liquid 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 handleability when applying the coating liquid and facilitate the formation of a coating film of uniform thickness. If the viscosity is outside this range, defects such as uneven thickness and streaks are likely to occur in the film during coating using a coater or the like.

[0161] The viscosity of the solution can be measured by the following method: Using an E-type viscometer (manufactured by Brookfield, trade name: DV-II+Pro), the viscosity of the solution at 25°C is measured. The rotation speed is set so that the torque is 10% to 90%, and the value is read when the viscosity stabilizes after 2 minutes have passed since the start of measurement.

[0162] [Preparation of Resin Composition] The resin composition can be produced by mixing the (A1) component with the (B1) component or the (B2) 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 added to a resin solution (varnish) of the (B1) component or the (B2) component and mixed therewith, or a resin solution of the (B1) component or the (B2) component may be added to a resin solution (varnish) of the non-thermoplastic polyimide precursor of the (A1) component and mixed therewith.

[0163] The acid or amine terminals of the (A1), (B1), and (B2) 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 setting the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component / diamine component) to less than 1.0, the (A1), (B1), and (B2) components can be acid-terminated. On the other hand, by setting the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component:diamine component) to a range greater than 1.0, the (A1), (B1), and (B2) components can be amine-terminated.

[0164] In preparing the resin composition of the present invention, when the (A1) component has a reactive functional group, it is preferable to use a (B2) component having a site reactive with the functional group. For example, when the (A1) component and the (B1) component or the (B2) component are linked by a covalent bond such as an amide bond, if an acid-terminated (A1) component is used, an amine-terminated (B1) component or a (B2) component is used, and if an amine-terminated (A1) component is used, an acid-terminated (B1) component or a (B2) component is used. In this way, by mixing the (A1) component and the (B1) component or the (B2) component in an acid-terminated state and the other in an amine-terminated state, a reaction occurs between the terminal functional groups of the (A1) component and the (B1) component or the (B2) component, and a resin composition containing the reactant (R1) component or the (R2) component can be prepared.

[0165] The method for producing a resin composition of the present invention will be described in more detail below, taking as a representative example a case where a resin composition containing an (R2) component is produced using the (A1) component and the (B2) component as raw materials. In this case, the method for producing a resin composition of the present invention can include the steps of: Step 1: preparing a resin solution of the (A1) component; Step 2: preparing a resin solution of the (B2) component; and Step 3: mixing the resin solution of the (A1) component with the resin solution of the (B2) component to synthesize the second reactant (R2) component.

[0166] In step 1, using the component (D) as a solvent facilitates preparation of a varnish using the component (A1). In step 2, using the component (C) as a solvent facilitates preparation of a varnish using the component (B2). The components (C) and (D) are preferably used so that the weight ratio (C / D) of the components (C) to (D) in the resin composition is within a range of 5 / 95 to 95 / 5, more preferably 10 / 90 to 90 / 10. Within the above range, it is possible to prepare a resin composition containing the components (A1), (B2), and (R2). Outside the above range, one of the components will precipitate, making it impossible to obtain a uniform resin composition.

[0167] In the above steps 1 to 3, when the component (A1) has an acid terminal, the component (B2) is one having an amine terminal, and when the component (A1) has an amine terminal, the component (B2) is one having an acid terminal. In this way, by mixing polymers with different terminal functional groups, the reaction product, component (R2), can be efficiently synthesized.

[0168] In step 3, the order of addition of the resin solution of component (A1) and the resin solution of component (B2) is not important. The weight ratio (A1 / B2) of components (A1) and (B2) mixed in step 3 is preferably within the range of 15 / 85 to 85 / 15. From the viewpoints of low dielectric loss tangent, improved tensile modulus, and low CTE, it is more preferably within the range of 20 / 80 to 80 / 20, even more preferably within the range of 35 / 65 to 65 / 35, and most preferably 40 / 60 to 60 / 40. If the weight ratio (A1 / B2) 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 realized. If it exceeds 85 / 15, the effect of lowering the dielectric loss tangent of the resin film may not be fully realized. Furthermore, in step 3, it is preferable that components (A1) and (B2) have a covalent bond. For example, when a resin solution of component (A1) and a resin solution of component (B2) are mixed and an amide bond is formed at the polymer chain terminal between a portion of component (A1) and a portion of component (B2) to form component (R2), the process is preferably carried out under an inert gas atmosphere. The formation of a new chemical bond such as an amide bond can be confirmed, for example, by nuclear magnetic resonance spectroscopy (NMR).

[0169] The above description has been given using a representative example of the production of a resin composition containing the component (R2) using the components (A1) and (B2) as raw materials. However, when the components (A1) and (B1) are used as raw materials to produce a resin composition containing the component (R1), steps 1 to 3 can be carried out by replacing the component (B2) with the component (B1) and the component (R2) with the component (R1).

[0170] The resin composition of the present invention, 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.

[0171] [Polyimide] The polyimide according to the second embodiment has a block structure in which a first polyimide and a second polyimide are covalently linked, where the first polyimide is a non-thermoplastic polyimide (A2) and the second polyimide is a soluble polyimide having structural units containing at least one of an aliphatic chain and an alicyclic skeleton (B2). Due to this block structure, the polyimide of the present invention contributes to a low dielectric loss tangent and a low CTE when formed into a film. In the resin film, the polyimide of the present invention may be referred to as "component (R3)."

[0172] The gel fraction of the polyimide according to the second embodiment is preferably 1.0 times or more, more preferably 1.2 times or more, the blending ratio of the A1 component. When the gel fraction is high, the A1 component forms a continuous phase, which is advantageous for achieving a low CTE, and the presence of a large amount of the R1 component or R2 component makes it easier to achieve a low dielectric effect.

[0173] The gel fraction of polyimide can be measured by the following method. The weight (weight before immersion) of a polyimide film of any size was measured. The film was immersed in THF and left to stand at room temperature for two days to elute the low-polarity resin component. After immersion, the film was dried at 90°C for 15 minutes, and the weight of the dried film (weight after immersion) was measured. The gel fraction can be calculated using the following formula: Gel fraction (%) = (weight after immersion) / (weight before immersion) x 100

[0174] The polyimide of the present invention can be produced by imidizing the polyamic acid contained in component (R1) or component (R2). The imidization method is not particularly limited, and a suitable method is, for example, heat treatment at a temperature in the range of 80 to 400°C for 1 to 24 hours. Heating may be performed at a constant temperature, or the temperature may be changed during the process. The polyimide of the present invention most preferably has a completely imidized structure. However, a portion of the polyimide may be in the form of 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) using 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.

[0175] [Resin Film] The resin film according to the second embodiment is a single-layer or multi-layer resin film, and at least one of the layers contains a polyimide (component (R3)) in which a non-thermoplastic polyimide component (A2) and a soluble polyimide component (B2) having a structural unit containing an aliphatic chain or an alicyclic skeleton are covalently bonded. The resin film according to the second embodiment has a polyimide layer (X) formed by imidizing a polyimide precursor using the resin composition and forming the polyimide into a film. Here, the non-thermoplastic polyimide of component (A2) is obtained by imidizing the non-thermoplastic polyimide precursor of component (A1) described in the resin composition. The component (R3) is obtained by imidizing component (R1) or component (R2). The resin film according to the second embodiment contains components (A2), (B2), and (R3), and thus has excellent high-frequency characteristics and a low CTE.

[0176] The resin film according to the second embodiment is preferably produced by, for example, applying a resin composition to a support substrate and drying it once or multiple times, followed by imidizing a polyamic acid, such as the non-thermoplastic polyimide precursor (A1) contained in the coating film. The method for applying the resin composition to the support 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, such as heating at a temperature in the range of 80 to 400°C for 1 to 24 hours, is preferably employed. The heating temperature may be constant, or the temperature may be changed during the process. The components (A2), (B2), and (R3) 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 absorbance of C═O stretching derived from the imide group and a calibration curve. By using a metal foil as the supporting substrate, the metal-clad laminate of the present invention described below can be produced.

[0177] The weight ratio (A2 / B2) of the (A2) component to the (B2) component in the resin film is preferably in the range of 15 / 85 to 85 / 15, more preferably in the range of 20 / 80 to 80 / 20, even more preferably in the range of 35 / 65 to 65 / 35, and most preferably in the range of 40 / 60 to 60 / 40. If the weight ratio (A2 / B2) is less than 15 / 85, the effect of lowering the CTE may not be fully exerted. On the other hand, if the weight ratio (A2 / B2) exceeds 85 / 15, the dielectric loss tangent may not be improved and high-frequency characteristics may be deteriorated.

[0178] Furthermore, the weight ratio of component (R3) to the total of components (A2), (B2), and (R3) in the resin film [R3 / (A2+B2+R3)] is preferably 0.2 or more, more preferably 0.4 or more, and most preferably 0.6 or more. If the weight ratio [R3 / (A2+B2+R3)] is less than 0.2, the presence of unreacted components (A2) and (B2) increases the number of terminal groups of each component, resulting in increased polarity and a deterioration in the dielectric loss tangent.

[0179] Furthermore, from the viewpoint of fully exhibiting the effects of the present invention, the total amount of the component (A2), the component (B2), and the component (R3) in the resin film 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).

[0180] The resin film of the present invention 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.

[0181] "Phase structure" 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 first 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 components (A2) and (B2) are compatible with each other, or may be 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 the sea phase.

[0182] When the phase structure of the resin composition according to the first 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. When the average equivalent circle diameter of the island phases is 0.010 μm to 10 μm, the linear expansion coefficient can be 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.

[0183] 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 The number density is preferably 0.01 to 0.200 particles / μm ２ Therefore, the linear expansion coefficient can be further reduced. The number density can be evaluated by the above-mentioned method.

[0184] (Thickness) The thickness of the resin film of the present invention is preferably 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 less than 5 μm, problems such as wrinkles may occur during transport during production of the resin film, or sufficient toughness may not be exhibited, making it impossible 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.

[0185] (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 at 10 GHz after 24 hours of humidity conditioning under conditions of a temperature of 24 to 26°C and a humidity of 45 to 55%, of 3.5 or less, more preferably 3.1 or less, and even more preferably 3.0 or less. If the 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.

[0186] (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 (Tan δ) of 0.0030 or less, more preferably 0.0022 or less, at 10 GHz after 24 hours of humidity conditioning under conditions of a temperature of 24 to 26°C and a humidity of 45 to 55%. If the dielectric dissipation factor exceeds 0.0030, 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.

[0187] (CTE) The resin film of the present invention preferably has a CTE of 50 ppm / K or less, more preferably in the range of 0 to 30 ppm / K. By having a CTE of 50 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.

[0188] (Glass transition temperature) The resin film of the present invention 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.

[0189] (Tensile Modulus of Elasticity) The resin film according to the second embodiment has a tensile modulus of elasticity of 1.0 GPa or more. It is more preferably in the range of 1.5 to 6.0 GPa, and even more preferably in the range of 1.5 GPa to 5.0 GPa. If the tensile modulus of elasticity is less than 1.0 GPa, tack occurs, making it difficult to obtain a film that is easy to process.

[0190] (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.

[0191] (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 less than 1%, the toughness will be deteriorated. The elongation can be measured by the method shown in the examples below.

[0192] (Edge tear resistance) The resin film according to the second embodiment preferably has an edge tear resistance of 0.1 N or more, more preferably 1 N or more, when the film has a thickness of 25 μm. If the edge tear resistance is less than 0.1 N, the film may become brittle and cracks may occur during circuit processing. The edge tear resistance can be measured by the method shown in the examples below.

[0193] The resin film of the present invention has both a low dielectric loss tangent and an excellent tensile modulus, and is also expected to have a low CTE, making it useful as a material for insulating layers in circuit boards and the like.

[0194] [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 of the present invention may also include any other layer than those described above.

[0195] 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.

[0196] 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.

[0197] 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.

[0198] [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.

[0199] [Electronic Device / Electronic Equipment] The electronic device and electronic equipment according to the second embodiment include the circuit board described above. Examples of the electronic device of the present invention 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 electronic equipment 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 equipment, the circuit board is preferably used as a component, such as wiring for moving parts, cables, and connectors.

[0200] [Third embodiment] <Resin composition> The structural units of the resin contained in the resin composition according to the third embodiment of the present invention are the same as those of the resin contained in the resin composition according to the second embodiment. The resin contained in the resin composition according to the third embodiment is different from the resin composition according to the second embodiment in which polymers react with each other, and also includes an oligomer-like copolymer.

[0201] (Preparation of Resin Composition) The resin composition according to the third embodiment may be produced, for example, by adding a raw material monomer for the component (B1) or a raw material monomer for the component (B2) to a resin solution of the component (A1) and mixing them, or by adding a raw material monomer for the component (A1) to a resin solution of the component (B1) or the component (B2) and mixing them. A solvent may be added together with the raw material monomer to be added.

[0202] The acid or amine terminals of the (A1), (B1), and (B2) 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 setting the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component / diamine component) to less than 1.0, the (A1), (B1), and (B2) components can be acid-terminated. On the other hand, by setting the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component:diamine component) to a range greater than 1.0, the (A1), (B1), and (B2) components can be diamine-terminated.

[0203] When preparing the resin composition according to the third embodiment, the order of addition of the raw material monomers of component (B1) or component (B2) is not particularly limited; they may be added simultaneously or in a predetermined order. This is because it is believed that the reaction between monomers with less steric hindrance and greater reactivity is prioritized. For example, when using an acid-terminated component (A1), the raw material monomers for component (B1) or component (B2) may be first added with an acid dianhydride and then with a diamine compound, or may be first added with a diamine compound and then with an acid dianhydride. Furthermore, when using an amine-terminated component (A1), the raw material monomers for component (B1) or component (B2) may be first added with an acid dianhydride and then with a diamine compound, or may be first added with a diamine compound and then with an acid dianhydride.

[0204] Similarly, the order of addition of the raw material monomers for component (A1) is not particularly limited; they may be added simultaneously or in a predetermined order. This is because it is believed that the reaction between monomers with less steric hindrance and greater reactivity is prioritized. For example, when using an acid-terminated component (B1) or (B2), the raw material monomers for component (A1) may be first added with an acid dianhydride and then with a diamine compound, or may be first added with a diamine compound and then with an acid dianhydride. Furthermore, when using an amine-terminated component (B1) or (B2), the raw material monomers for component (A1) may be first added with an acid dianhydride and then with a diamine compound, or may be first added with a diamine compound and then with an acid dianhydride.

[0205] The method for producing a resin composition of the present invention will be described in more detail below, taking as a representative example a case where a resin composition containing component (R2) is produced using raw material monomers of component (A1) and component (B2). In this case, the method for producing a resin composition of the present invention can include: Step 1B of preparing a resin solution of component (B2); Step 2B of adding raw material monomers of component (A1) to the resin solution of component (B2) to prepare a mixed solution; and Step 3B of adding raw material monomers of component (A1) to the mixed solution to synthesize component (A1) and component (R2).

[0206] In step 1B, the use of the first solvent as the solvent facilitates the preparation of a varnish using component (B2).In steps 2B and 3B, the addition of the second solvent as the solvent simultaneously with, before, or after the addition of the raw material monomers for component (A1) allows the synthesis reaction of components (A1) and (R2) to proceed efficiently.

[0207] The weight ratio (C / D) of the first solvent (C) to the second solvent (D) in the coating liquid according to the third embodiment is preferably in the range of 5 / 95 to 95 / 5, and more preferably in the range of 10 / 90 to 90 / 10. Within the above range, it is possible to prepare a resin composition containing the components (A1), (B2), and (R2).

[0208] The weight ratio (total amount of A1 monomers / B2) of the total amount of raw material monomers of component (A1) added in steps 2 and 3 to component (B2) is preferably within the range of 15 / 85 to 85 / 15, more preferably within the range of 35 / 65 to 65 / 35, and most preferably within the range of 40 / 60 to 60 / 40, from the viewpoint of achieving a low dielectric loss tangent and a low CTE. If the weight ratio (total amount of A1 monomers / B2) 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, whereas if it exceeds 85 / 15, the effect of lowering the dielectric loss tangent of the resin film may not be fully exhibited.

[0209] Furthermore, in step 3, the acid dianhydride and diamine compound, which are raw material monomers for component (A1), are reacted efficiently to preferentially synthesize component (A1), and a covalent bond is formed between polymer chains of a portion of the generated component (A1) and a portion of the generated component (B2) to form component (R2), so step 3 is preferably carried out under conditions of an inert gas atmosphere. The formation of a new chemical bond such as an amide bond can be confirmed, for example, by nuclear magnetic resonance spectroscopy (NMR).

[0210] The above description has been given using as a representative example the case where a resin composition containing the component (R2) is produced using the raw material monomers of the component (A1) and the component (B2). However, when a resin composition containing the component (R1) is produced using the raw material monomers of the component (A1) and the component (B1), the component (B2) is replaced with the component (B1) and the component (R2) is replaced with the component (R1), and steps 1B to 3B described above are carried out.

[0211] Furthermore, when a resin composition is produced using the component (A1) and the raw material monomers of the component (B1) or the component (B2), the process can be carried out in accordance with the above steps 1B to 3B.

[0212] 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.

[0213] [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 (HLC-8420GPC manufactured by Tosoh Corporation, GPC column: TSKgel-GMH HR Measurements were performed using two 1000-H (Tosoh Corporation, inner diameter 7.8 mm x length 30 cm) filters. 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 0.7 mL / min, the measurement temperature was 40°C, and the sample injection volume was 100 μL. The results are shown in Tables 1A and 4A.

[0214] [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 value was read when the viscosity stabilized 2 minutes after the start of measurement. The values ​​are shown in Tables 1A, 2B, 3B, 4A, and 5B.

[0215] [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, product name: RSA G2) on a polyimide film measuring 5 mm x 20 mm, at a temperature increase 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). Note that 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 ８ 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 ８ Those exhibiting a modulus of elasticity of 1 Pa or more were rated as "non-thermoplastic." The results obtained are shown in Tables 1B, 2D, 4B, and 6A.

[0216] "Confirmation of the continuous phase" The confirmation of the continuous phase and the average circle equivalent diameter and number density of the island phases were measured using the following method. The resin film was cut and embedded in epoxy resin, and then a 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.

[0217] 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, dark areas were determined to be the second structure (B2) component, and light areas were determined to be the first structure (A2 component). When the sea phase was the first structure, the first structure 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 sea-island structure, it was marked with an A, and when it was a homogeneous phase, it was marked with a B. The results are shown in Tables 2C, 3C, and 6B.

[0218] [Measurement of coefficient of linear expansion (CTE)] A polyimide film measuring 3 mm x 20 mm was heated from 30°C to 180°C at a constant heating rate while applying a load of 5.0 g using a thermomechanical analyzer (trade name: TMA / 7100, manufactured by Hitachi High-Technologies Corporation (formerly Seiko Instruments Inc.)), and then held at that temperature for 10 minutes. The film was then cooled at a rate of 5°C / min to determine the average coefficient of thermal expansion (coefficient of linear expansion) from 180°C to 100°C. The results are shown in Tables 1B, 2C, 3C, 4B, and 6B.

[0219] [Measurement of Dielectric Constant (Dk) and Dielectric Loss Tangent (Df)] The 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 under humidity control were measured after the polyimide film used for the measurement was left for 24 hours under conditions of a temperature of 24 to 26°C and a humidity of 45 to 55%. The results are shown in Tables 1B, 2C, 3C, 4B, and 6B.

[0220] [Measurement of Tensile Modulus and Elongation] A tensile test was performed 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, 2D, 4B, and 6A.

[0221] [Measurement of Edge Tear Resistance] A polyimide film measuring 20 mm wide and 200 mm long was conditioned for 24 hours at a temperature of 23°C and a relative humidity of 50% RH to obtain a measurement film. Using a dedicated test jig, the measurement film was placed on the bent portion of the jig and pulled at a rate of 200 mm / min using a Strograph R-1 (manufactured by Toyo Seiki Seisakusho, Ltd.) to measure edge tear resistance. Five test pieces were used, and the average value calculated based on a 25 μm thickness was calculated. The results are shown in Tables 2D and 6A.

[0222] "Mass ratio of first structure and second structure" Based on the above-mentioned criteria, the mass ratio of each structure in the copolymer after polymerization was determined. The structural portion in which the distance between aromatic rings calculated from each bond distance was 8.0 Å or less was determined to be the first structure. Based on the above-mentioned criteria, the first structure and the second structure were determined, and the mass ratio of each structure was calculated from the structure and blending ratio of the monomers used as raw materials for the copolymer, and the structure after the reaction. The results obtained are shown in Tables 2B and 3B.

[0223] "Gel fraction" The weight (weight before immersion) of a polyimide film of any size was measured. The film was immersed in THF and left to stand at room temperature for 2 days to elute the low-polarity resin component. After immersion, the film was dried at 90°C for 15 minutes, and the weight of the dried film (weight after immersion) was measured. The gel fraction was calculated using the following formula. The results are shown in Table 2D. Gel fraction (%) = (weight after immersion) / (weight before immersion) x 100

[0224] [Measurement of Surface Roughness of Copper Foil] 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 calculated. The copper foil was fixed to a smoothly polished metal plate with a liquid adhesive. The ten-point average roughness Rzjis was calculated after performing a leveling process to correct for tilt using the software provided with the AFM device. The roughness Rzjis was 0.6 μm.

[0225] 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 6FDA: 4,4'-(hexafluoroisopropylidene)diphthalic anhydride BTDA: 3,3',4,4'-benzophenonetetracarboxylic dianhydride 26DHN-TME: 2,6-naphthalenebis(trimellitic acid monoester acid anhydride) (CAS number: 115383-00-1) BP-TME: p-biphenylenebis(trimellitic acid monoester acid anhydride) (CAS number: 10340-81-5) BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride BPADA: 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane DATP: 4,4''-diamino-p-terphenyl APAB: 4-aminophenyl 4-aminobenzoate H20: Diamine H20 (manufactured by Okamura Oil Mills Co., Ltd.) NMP: N-methyl-2-pyrrolidone (SP value: 11.3) DMAc: N,N-dimethylacetamide (SP value: 10.8)

[0226] Experimental Example 1 (Synthesis Example 1) 28.5921 g of 6FDA (0.06435 mol), 31.4080 g of DDA (0.05850 mol), 84 g of NMP, and 56 g of xylene (SP value: 8.8) 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 in an amount such that the solids concentration after polymerization was 30.6 wt% to complete imidization, preparing solvent-soluble polyimide solution A. The solvent-soluble polyimide contained in solvent-soluble polyimide solution A was acid-terminated. The measurement results are shown in Tables 1A and 1B. The results in Table 1B are measurements taken after molding a resin film of the thickness shown in Table 1B and imidizing it. The imidization and film formation were carried out by heat treatment from room temperature to 320° C. at a temperature increase rate of 5° C. / min, similar to the method for producing a resin film described below.

[0227] Synthesis Example 2: 32.6921 g of 6FDA (0.07358 mol), 39.3079 g of DDA (0.07321 mol), 100.8 g of NMP, and 67.20 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 in an amount such that the solids concentration after polymerization was 29.4 wt% to complete imidization, preparing solvent-soluble polyimide solution B. The solvent-soluble polyimide contained in solvent-soluble polyimide solution B was acid-terminated. The measurement results are shown in Tables 1A and 1B.

[0228] Synthesis Example 3: 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 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 in an amount such that the solids concentration after polymerization was 21.2 wt %, completing the imidization to prepare a solvent-soluble polyimide solution C. The solvent-soluble polyimide contained in the solvent-soluble polyimide solution C was amine-terminated. The measurement results are shown in Tables 1A and 1B.

[0229] Synthesis Example 4: 29.8836 g of BTDA (0.09256 mol), 45.1759 g of DDA (0.08414 mol), 105.08 g of NMP, and 70.06 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 such that the solids concentration after polymerization was 32.2 wt %, completing the imidization to prepare Solvent-Soluble Polyimide Solution D. The solvent-soluble polyimide contained in Solvent-Soluble Polyimide Solution D was acid-terminated. The measurement results are shown in Tables 1A and 1B.

[0230] (Synthesis Example 5) Under a nitrogen stream, 13.8095 g of m-TB (0.06496 mol) and an amount of DMAc 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, 31.1905 g of 26DHN-TME (0.06074 mol) was added, and the mixture was stirred at room temperature for one week to carry out the polymerization reaction, thereby preparing non-thermoplastic polyamic acid solution E. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution E was amine-terminated. The measurement results are shown in Tables 1A and 1B.

[0231] (Synthesis Example 6) Under a nitrogen stream, 13.3255 g of m-TB (0.06268 mol) and an amount of NMP such that the solids concentration after polymerization would be 10 wt% were added to a 500 mL separable flask and stirred at room temperature to dissolve. Next, 31.6745 g of 26DHN-TME (0.06168 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 F. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution F was amine-terminated. The measurement results are shown in Tables 1A and 1B.

[0232] (Synthesis Example 7) Under a nitrogen stream, 12.3045 g of m-TB (0.05788 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 the mixture was stirred at room temperature to dissolve. Next, 32.6955 g of 26DHN-TME (0.06367 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 acid-terminated. The measurement results are shown in Tables 1A and 1B.

[0233] Synthesis Example 8: Under a nitrogen stream, 13.2784 g of m-TB (0.06245 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 dissolved by stirring at room temperature. Next, 31.7220 g of BP-TME (0.05839 mol) was added, and the mixture was allowed to polymerize by stirring at room temperature for one week to prepare non-thermoplastic polyamic acid solution H. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution H was amine-terminated. The measurement results are shown in Tables 1A and 1B.

[0234] Synthesis Example 9: Under a nitrogen stream, 19.6062 g of m-TB (0.09222 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 dissolved by stirring at room temperature. Next, 25.3938 g of BPDA (0.08622 mol) was added, and the mixture was stirred at room temperature for 5 hours 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 amine-terminated. The measurement results are shown in Tables 1A and 1B.

[0235] (Synthesis Example 10) Under a nitrogen stream, 13.8095 g of m-TB (0.06496 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, 31.1905 g of 26DHN-TME (0.06074 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. The measurement results are shown in Tables 1A and 1B.

[0236] Synthesis Example 11: 36.1328 g of BPDA (0.12271 mol), 35.8672 g of H2O (0.11156 mol), 100.80 g of NMP, and 67.20 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 an amount of xylene was added to achieve a solids concentration of 30.0 wt% after polymerization to complete imidization, preparing solvent-soluble polyimide solution K. The solvent-soluble polyimide contained in solvent-soluble polyimide solution K was acid-terminated. The measurement results are shown in Tables 1A and 1B.

[0237] Synthesis Example 12: Under a nitrogen stream, 13.3182 g of m-TB (0.06264 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, 31.6786 g of BP-TME (0.05856 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 L. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution L was amine-terminated. The measurement results are shown in Tables 1A and 1B.

[0238] (Synthesis Example 13) Under a nitrogen stream, 6.3079 g of m-TB (0.02967 mol), 8.6844 g of TPE-R (0.02967 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, 30.0077 g of BP-TME (0.05548 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 M. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution M was amine-terminated. The measurement results are shown in Tables 1A and 1B.

[0239] Synthesis Example 14: 38.0916 g of 6FDA (0.08568 mol), 33.9084 g of DDA (0.06346 mol), 108.00 g of NMP, and 67.20 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 an amount of xylene was added to achieve a solids concentration of 30.0 wt% after polymerization to complete imidization, preparing solvent-soluble polyimide solution N. The solvent-soluble polyimide contained in solvent-soluble polyimide solution N was acid-terminated. The measurement results are shown in Tables 1A and 1B.

[0240] Synthesis Example 15: A 500 mL separable flask was charged with 37.2585 g of BPADA (0.07153 mol), 34.7415 g of DDA (0.06502 mol), 108.00 g of NMP, and 72.00 g of xylene, and the mixture was thoroughly mixed at 40° C. for 1 hour to prepare a polyamic acid solution. The polyamic acid solution was heated to 190° C. and stirred for 5 hours. Xylene was added in an amount such that the solids concentration after polymerization was 30.0 wt %, completing the imidization and preparing a solvent-soluble polyimide solution O. The solvent-soluble polyimide contained in the solvent-soluble polyimide solution O was acid-terminated. The measurement results are shown in Tables 1A and 1B.

[0241] Synthesis Example 16: 27.9816 g of BPDA (0.09503 mol), 36.9256 g of DDA (0.06911 mol), 7.0927 g of BAPP (0.01728 mol), 108.00 g of NMP, and 72.00 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 an amount of xylene was added to achieve a solids concentration of 30.0 wt % after polymerization to complete imidization, preparing a solvent-soluble polyimide solution P. The solvent-soluble polyimide contained in the solvent-soluble polyimide solution P was acid-terminated. The measurement results are shown in Tables 1A and 1B.

[0242] Synthesis Example 17: Under a nitrogen stream, 15.2921 g of DATP (0.05874 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, 29.7079 g of BP-TME (0.05492 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 Q. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution Q was amine-terminated. The measurement results are shown in Tables 1A and 1B.

[0243] (Synthesis Example 18) Under a nitrogen stream, 20.2636 g of APAB (0.08884 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, 24.7364 g of BPDA (0.08307 mol) was added, and the mixture was stirred at room temperature for one week to carry out a polymerization reaction, thereby preparing a non-thermoplastic polyamic acid solution R. The non-thermoplastic polyamic acid contained in the non-thermoplastic polyamic acid solution R was amine-terminated. The measurement results are shown in Tables 1A and 1B.

[0244] Synthesis Example 19: Under a nitrogen stream, 20.5415 g of m-TB (0.09663 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 dissolved by stirring at room temperature. Next, 24.4585 g of BPDA (0.08213 mol) was added, and the mixture was allowed to polymerize by stirring at room temperature for one week to prepare non-thermoplastic polyamic acid solution S. The non-thermoplastic polyamic acid contained in non-thermoplastic polyamic acid solution S was amine-terminated. The measurement results are shown in Tables 1A and 1B.

[0245] Synthesis Example 20: 27.1745 g of BPDA (0.09229 mol), 44.8255 g of DDA (0.08390 mol), 100.80 g of NMP, and 72.00 g of xylene were placed in a 500 mL separable flask and mixed thoroughly at 50° C. for 3 hours to prepare solvent-soluble polyamic acid solution T. The solvent-soluble polyamic acid contained in solvent-soluble polyamic acid solution T was acid-terminated. The measurement results are shown in Tables 1A and 1B.

[0246] [Synthesis of Resin Composition] (Synthesis of Resin Composition 1) 15.42 g of solvent-soluble polyimide solution A was placed in a 500 mL separable flask and stirred under a nitrogen stream. Next, 30.00 g of non-thermoplastic polyamic acid solution E and 18.41 g of DMAc were added, and the polymerization reaction was continued at room temperature for one week to obtain Resin Composition 1 (copolymer). 1H NMR measurement of Resin Composition 1 was performed, and an NH peak derived from the amide bond formed by the solvent-soluble polyimide solution A and the non-thermoplastic polyamic acid solution E was detected.

[0247] Resin compositions 2 to 28 were prepared in the same manner as in the synthesis of resin composition 1, except that the raw material compositions shown in Tables 2A, 2B, 3A and 3B were used.

[0248] [Preparation of Resin Film] (Preparation of Resin Film 1) Resin composition 1 was uniformly applied to copper foil 1 (electrolytic copper foil, thickness: 12 μm, resin side roughness Rzjis: 0.6 μm) to a thickness of 30 μm after curing, and then heated and dried at 100 to 120°C for 10 minutes to remove the solvent. Further, heat treatment was performed from room temperature to 320°C at a heating rate of 5°C / min to complete imidization, and copper-clad laminate A was obtained. Next, the copper foil of the obtained copper-clad laminate A was etched and removed using an aqueous ferric chloride solution to obtain resin film 1 of resin composition 1. The various evaluation results of the obtained resin film 1 are as follows: Dk: 2.9, Df: 0.0015, CTE: 10 ppm / K, Tg: 221°C, tensile modulus: 3.4 GPa, elongation: 34%, edge tear resistance: 68 N, 180°C storage modulus: 422.8 MPa

[0249] Resin films 2 to 28 were obtained under the same conditions as for preparing resin film 1, except that resin compositions 2 to 28 were used and the thicknesses after curing were set to the conditions in Tables 2C and 3C. Resin film 27 could not be formed due to varnish separation. Resin film 28 exhibited a high Df. The results of various property evaluations are shown in Tables 2C, 2D, and 3C.

[0250] From Tables 2B and 3B, it was confirmed that in resin compositions 1 to 26, the mass ratio of the first structure to the second structure satisfied the predetermined conditions, and therefore a resin film having a tensile modulus of 1.0 GPa or more and a dielectric dissipation factor of 0.0030 or less could be obtained. On the other hand, from Table 1B, it was not possible to achieve both an excellent tensile modulus and a low dielectric dissipation factor with a single polymer.

[0251] Experimental Example 2 (Synthesis Example 1A) A 500 mL separable flask was charged with 28.5921 g of 6FDA (0.06435 mol), 31.4080 g of DDA (0.05850 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 polyamic acid solution was heated to 190°C and stirred for 5 hours. Xylene was added to the solution to a solids concentration of 30.6 wt% to complete imidization, preparing solvent-soluble polyimide solution 1A. The solvent-soluble polyimide contained in solvent-soluble polyimide solution 1A was acid-terminated. The measurement results are shown in Tables 4A and 4B. The results in Table 4B are measurements taken after molding a resin film of the thickness shown in Table 4B and imidizing it. The imidization and film formation were carried out by heat treatment from room temperature to 320° C. at a temperature increase rate of 5° C. / min, similar to the method for producing a resin film described below.

[0252] (Synthesis Example 2A) 32.6921 g of 6FDA (0.07358 mol), 39.3079 g of DDA (0.07321 mol), 100.8 g of NMP, and 67.20 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 to a solids concentration of 29.4 wt % to complete imidization. Solvent-soluble polyimide solution 2A (solids concentration: 29.4 wt %, weight average molecular weight: 61,437, number average molecular weight: 32,775, viscosity: 1294 cP) was prepared. The solvent-soluble polyimide contained in solvent-soluble polyimide solution 2A was acid-terminated. The measurement results are shown in Tables 4A and 4B.

[0253] (Synthesis Example 3A) 21.7287 g of 6FDA (0.04882 mol), 14.2713 g of Diamine H20 (0.04439 mol), 50.40 g of NMP, and 33.60 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 to a solids concentration of 31.8 wt% to complete imidization. A solvent-soluble polyimide solution 3A (solids concentration: 31.8 wt%, weight average molecular weight: 26,370, number average molecular weight: 12,606, viscosity 238.1 cP) was prepared. The solvent-soluble polyimide contained in the solvent-soluble polyimide solution 3A is acid-terminated. The measurement results are shown in Table 4A and Table 4B.

[0254] Synthesis Example 4A: 27.1745 g of BPDA (0.09229 mol), 44.8255 g of DDA (0.08390 mol), 100.80 g of NMP, and 72.00 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 such that the solids concentration after polymerization was 30.0 wt% to complete the imidization, preparing solvent-soluble polyimide solution 4A. The solvent-soluble polyimide contained in solvent-soluble polyimide solution 4A was acid-terminated. The measurement results are shown in Tables 4A and 4B.

[0255] Synthesis Example 5A: 27.1745 g of BPDA (0.09229 mol), 44.8255 g of DDA (0.08390 mol), 100.80 g of NMP, and 72.00 g of xylene were placed in a 500 mL separable flask and mixed thoroughly at 50° C. for 3 hours to prepare solvent-soluble polyamic acid solution 5A. The solvent-soluble polyamic acid contained in solvent-soluble polyamic acid solution 5A was acid-terminated. The measurement results are shown in Tables 4A and 4B.

[0256] "Synthesis of copolymer" (Resin composition 1A) 9.19 g of solvent-soluble polyimide solution A was placed in a 500 mL separable flask and stirred under a nitrogen stream. Next, 5.999 g of 26DHN-TME (0.01180 mol) was added, followed by the addition of 2.6069 g of m-TB (0.01228 mol) and 42.14 g of DMAc. The mixture was stirred at room temperature for 5 hours to carry out a polymerization reaction, thereby preparing Resin composition 1A (viscosity: 17,185 cP). Resin composition 1A １ H NMR measurement was carried out, and an NH peak derived from the amide bond formed by the solvent-soluble polyimide solution 1A and m-TB was detected.

[0257] Resin compositions 2A to 17A were prepared in the same manner as for resin composition 1A, except that the raw material compositions shown in Tables 5A and 5B were used.

[0258] Resin composition 1A was uniformly applied to copper foil 1 (electrolytic copper foil, thickness: 12 μm, resin side roughness Rzjis: 0.6 μm) to a cured thickness of 25 μm, and then heated and dried at 100-120 ° C for 10 minutes to remove the solvent. Further, heat treatment was performed from room temperature to 320 ° C at a temperature increase rate of 5 ° C / min to complete imidization, and copper-clad laminate 1A was obtained. Next, the copper foil of the obtained copper-clad laminate 1A was etched and removed using an aqueous ferric chloride solution to obtain resin film 1A (polyimide film). Various evaluation results of resin film 1A are as follows: Dk: 3.4, Df: 0.0026, CTE: 19 ppm / K, Tg: 228 ° C, tensile modulus: 6.9 GPa, elongation: 9%, edge tear resistance: 45 N, storage modulus at 180 ° C: 3281 MPa

[0259] Resin films 2A to 17A were obtained in the same manner as for Resin film 1A. The results of various evaluations are shown in Tables 6A and 6B.

[0260] From Table 6, it was confirmed that in resin films 1A to 17A, the first structure and the second structure satisfied the specified conditions, and therefore resin films having a tensile modulus of elasticity of 1.0 GPa or more and a dielectric tangent of 0.0030 or less were obtained.

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[0275]

[0276] 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.

[0277] The resin composition according to the embodiment has an excellent tensile modulus and a low dielectric loss tangent, and therefore has high industrial applicability.

Claims

1. A copolymer comprising: a first structure including two or more aromatic rings; and a second structure having a chain structure in which carbon atoms are bonded to each other by single bonds, wherein the number of carbon atoms constituting the chain structure is 6 or more, the distance between the aromatic rings in the first structure is 8.0 Å or less, the content of the first structure is 15 to 85 mass%, and the content of the second structure is 15 to 85 mass%.

2. A resin substrate comprising the copolymer according to claim 1.

3. The resin substrate according to claim 2, wherein the first structure constitutes a continuous phase.

4. A resin composition comprising: a component (A1) which is a non-thermoplastic polyimide precursor; a component (B1) which is a soluble polyimide precursor having a structural unit containing at least one of an aliphatic chain and an alicyclic skeleton; and a first reactant in which the above are linked by a covalent bond.

5. A resin composition comprising: a component (A1) which is a thermoplastic polyimide precursor; a component (B2) which is a soluble polyimide having structural units containing at least one of an aliphatic chain and an alicyclic skeleton; and a second reactant in which the above are linked by a covalent bond.

6. The resin composition according to claim 4, wherein the first reactant is an amide bond between the component (A1) and the component (B1) at the polymer chain terminal.

7. The resin composition according to claim 5, wherein the second reactant is an amide bond between the component (A1) and the component (B2) at the polymer chain terminal.

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

9. The resin composition according to claim 5, wherein the weight ratio (A1 / B2) of the component (A1) to the component (B2) is within the range of 15 / 85 to 85 / 15.

10. The resin composition according to claim 4 or 5, further comprising a resin having an SP value of 10.3 to 19.5 (J / cm ３ ) １／２ and a first organic solvent having an SP value of 19.7 to 30.8 (J / cm ３ ) １／２ and a second organic solvent within the range of 11. A polyimide comprising: (A2) a first polyimide which is a non-thermoplastic polyimide; and (B2) a second polyimide which is a soluble polyimide having a structural unit containing at least one of an aliphatic chain and an alicyclic skeleton.

12. A resin film comprising a single or multiple polyimide layers, wherein at least one of the polyimide layers contains a polyimide in which a component (A2) which is a non-thermoplastic polyimide and a component (B2) which is a soluble polyimide having a structural unit containing an aliphatic chain or an alicyclic skeleton are linked by a covalent bond.

13. The resin film according to claim 12, which has a dielectric loss tangent of 0.003 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%.

14. The resin film according to claim 12, which has a dielectric loss tangent at 10 GHz of 0.0022 or less.

15. 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 substrate according to claim 2 or the resin film according to claim 12.

16. 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 the insulating resin layer, wherein at least one of the insulating resin layers is constituted by the resin base material according to claim 2 or the resin film according to claim 12.

17. An electronic device comprising the circuit board according to claim 16.

18. An electronic device comprising the circuit board according to claim 16.

19. A method for producing the resin composition according to claim 5, comprising: step 1 of preparing a resin solution of the component (A1); step 2 of preparing a resin solution of the component (B2); and step 3 of mixing the resin solution of the component (A1) and the resin solution of the component (B2) to synthesize the second reactant.

20. A method for producing a resin composition according to claim 19, wherein when the component (A1) has a reactive functional group, the component (B2) has a site which reacts with the functional group.

21. The method for producing a resin composition according to claim 19, wherein the weight ratio (A1 / B2) of the component (A1) to the component (B2) mixed in step 3 is within the range of 15 / 85 to 85 / 15.

22. A method for producing a resin composition according to claim 5, comprising: step 1 of preparing a resin solution of the component (B2); step 2 of adding a raw material monomer of the component (A1) to the resin solution of the component (B2) to prepare a mixed solution; and step 3 of adding a raw material monomer of the component (A1) to the mixed solution to synthesize the component (A1) and the second reactant.

23. A method for producing a resin composition according to claim 22, wherein the weight ratio (total amount of A1 monomers / B2) of the total amount of raw material monomers of the (A1) component added in steps 2 and 3 to the (B2) component is within the range of 15 / 85 to 85 / 15.

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