Composition for high frequency substrate material, polyimide film, laminate, substrate for circuit, and antenna

Abstract

To provide a polyimide resin for a high frequency substrate material which achieves both a low dielectric constant and a low coefficient of linear expansion.SOLUTION: A polyimide resin for a high frequency substrate material is composed of an acid anhydride and diamine, where the acid anhydride is one or more selected from the group consisting of a compound represented by general formula (A-1), and the diamine is one or more kinds selected from the group consisting of a compound represented by general formula (B-1).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to polyimide resins, compositions, polyimide films, laminates, circuit boards, and antennas for use as high-frequency substrate materials, as well as polyamic acids and compositions for use as high-frequency substrate materials. [Background technology]

[0002] Polyimide resins with low dielectric loss tangents and low linear expansion coefficients have been studied as materials for high-frequency substrates (see, for example, Patent Document 1). Conventionally, a low dielectric constant and a low linear expansion coefficient are generally in a trade-off relationship, and it has been difficult to achieve both, and no polyimide resins for use as high-frequency substrate materials that achieve both a low dielectric constant and a low linear expansion coefficient have been found. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-088880 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a polyimide resin for use as a high-frequency substrate material that has both a low dielectric constant and a low coefficient of linear expansion. [Means for solving the problem]

[0005] <1> consisting of an acid anhydride and a diamine, The acid anhydride is at least one compound selected from the group consisting of compounds represented by the following general formula (A-1): The polyimide resin for high-frequency substrate materials is such that the diamine is at least one selected from the group consisting of compounds represented by the following general formula (B-1) and compounds represented by the following general formula (B-2): [ka] In the general formula (A-1), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; l represents an integer of 0 to 3, and when l is 0, it represents that there is no bond; m represents an integer of 0 to 3; n represents an integer of 0 to 5, If n is 0, then at least one R 1 has a fluorine atom, R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 2 may be bonded to each other to form a cycloalkyl group, At least one R 2 represents a fluoroalkyl group which may have a substituent, Each X is independently -O-, -C(R 3 )2-, and -SO2-; R 3 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 3 may be bonded to each other to form a cycloalkyl group. [ka] In the general formula (B-1), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; l represents an integer of 1 to 3, m represents an integer of 0 to 3; n represents an integer of 0 to 5, o represents an integer from 0 to the maximum number of substituents; R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 2 may be bonded to each other to form a cycloalkyl group, At least one R 2 represents a fluoroalkyl group which may have a substituent, Each X is independently -O-, -C(R 3 )2-, and -SO2-; R 3 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 3 may be bonded to each other to form a cycloalkyl group. [ka] In the general formula (B-2), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; At least one R 1 has a fluorine atom, m's each independently represent an integer of 0 to 2, o represents an integer from 0 to the maximum number of substituents. <2> The general formula (A-1) is either of the following general formula (A-1a) and the following general formula (A-1b): <1> The polyimide resin is described in [ka] In the general formula (A-1a), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; At least one R1 has a fluorine atom, m represents an integer of 0 to 3; [ka] In the general formula (A-1b), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; n represents an integer of 1 to 5, R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 2 may be bonded to each other to form a cycloalkyl group, At least one R 2 represents a fluoroalkyl group which may have a substituent, Each X is independently -O-, -C(R 3 )2-, and -SO2-; R 3 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 3 may be bonded to each other to form a cycloalkyl group. <3> The general formula (B-1) is either the following general formula (B-1a) or the following general formula (B-1b): The general formula (B-2) is the following general formula (B-2a): <1> or <2> The polyimide resin is described in [ka] In the general formula (B-1a), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; o represents an integer of 0 to 4. [ka] In the general formula (B-1b), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; m represents an integer of 1 to 3; o represents an integer from 0 to the maximum number of substituents. [ka] In the general formula (B-2a), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; At least one R 1 has a fluorine atom, o represents an integer of 0 to 8. <4> consisting of an acid anhydride and a diamine, The acid anhydride is at least one selected from the group consisting of compounds represented by the following general formulas (A-2a) to (A-2g): The polyimide resin for high-frequency substrate materials is such that the diamine is at least one selected from the group consisting of compounds represented by the following general formula (B-3) and compounds represented by the following general formula (B-4): [ka] In the general formulas (A-2a) to (A-2g), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; l represents an integer of 1 to 3, R2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. [ka] In the general formula (B-3), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; l represents an integer of 1 to 3, m represents an integer of 0 to 3; n represents an integer of 0 to 5, o represents an integer from 0 to the maximum number of substituents; R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; At least one R 2 represents a fluoroalkyl group which may have a substituent, Each X is independently -O-, -C(R 3 )2-, and -SO2-; R 3 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 3 may be bonded to each other to form a cycloalkyl group. [ka] In the general formula (B-4), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; m's each independently represent an integer of 0 to 2, o represents an integer from 0 to the maximum number of substituents. <5> The general formula (B-3) is either the following general formula (B-3a) or the following general formula (B-3b): The general formula (B-4) is the following general formula (B-4a): <4> The polyimide resin is described in [ka] In the general formula (B-3a), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; o represents an integer of 0 to 4. [ka] In the general formula (B-3b), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; m represents an integer of 1 to 3; o represents an integer from 0 to the maximum number of substituents. [ka] In the general formula (B-4a), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; At least one R 1 has a fluorine atom, o represents an integer of 0 to 8. <6> The dielectric constant at 10 GHz is 2.6 or less, The linear expansion coefficient is 50 ppm / K or less. <1> from <5> The polyimide resin according to any one of the above items. <7> A polyimide resin having a structural unit of the following general formula (1): [ka] In the general formula (1), R a The (CO)4 moiety represents a tetravalent group derived from a tetravalent tetracarboxylic acid having two or more carbon atoms, and R b The (N)2 moiety represents a tetravalent group derived from a divalent diamine having two or more carbon atoms, The free volume fraction and the average number of adjacent atoms of the amorphous polyimide resin in an equilibrium state at a temperature of 300 K and a pressure of 1 atm, as calculated by molecular dynamics calculation, satisfy the following condition (1) or (2): (1) The free volume fraction is 0.23 to 0.38, and the average number of adjacent atoms is 3.80 to 4.75, or (2) the free volume fraction is 0.24 to 0.38, and the average number of adjacent atoms is 3.94 to 4.95; the average number of adjacent atoms is an average of the number of adjacent atoms per number of atoms constituting the system of the molecular dynamics calculation, The polyimide resin for use as a high-frequency substrate material is such that the number of adjacent atoms is the total number of atom pairs that satisfies the following conditions (a) and (b): (a) Atomic pairs that share one edge of a Voronoi cell with each atom as a kernel point (b) Atom pairs separated by four or more bonds, or atom pairs between different molecules <8> the free volume fraction is 0.23 to 0.32, and the average number of adjacent atoms is 3.90 to 4.60; <7> The polyimide resin is described in <9> the free volume fraction is 0.23 to 0.32, and the average number of adjacent atoms is 3.90 to 4.60; The above-mentioned compound does not have a trifluoromethyl group. <7> The polyimide resin is described in <10> the free volume fraction is 0.24 to 0.32, and the average number of adjacent atoms is 3.90 to 4.50; The above-mentioned compound does not have a trifluoromethyl group. <7> The polyimide resin is described in <11> the free volume fraction is 0.28 to 0.32, and the average number of adjacent atoms is 3.90 to 4.50; The above-mentioned compound does not have a trifluoromethyl group. <7> The polyimide resin is described in <12> The free volume fraction and the average number of adjacent atoms of the amorphous polyimide resin in an equilibrium state at a temperature of 300 K and a pressure of 1 atm, as calculated by molecular dynamics calculation, satisfy the following condition (1) or (2): (1) The free volume fraction is 0.23 to 0.38, and the average number of adjacent atoms is 3.80 to 4.75, or (2) the free volume fraction is 0.24 to 0.38, and the average number of adjacent atoms is 3.94 to 4.95; the average number of adjacent atoms is an average of the number of adjacent atoms per number of atoms constituting the system of the molecular dynamics calculation, the number of adjacent atoms is the total number of atom pairs that satisfy the following conditions (a) and (b): <1> from <11> The polyimide resin according to any one of the above items. (a) Atomic pairs that share one edge of a Voronoi cell with each atom as a kernel point (b) Atom pairs separated by four or more bonds, or atom pairs between different molecules <13> The above <1> from <12> 1. A composition for use as a high-frequency substrate material, comprising the polyimide resin according to any one of claims 1 to 9. <14> The above <1> from <12> 1. A polyimide film for use as a high-frequency substrate material, comprising the polyimide resin according to any one of claims 1 to 9. <15> a metal layer; The above <1> from <12> and a layer containing the polyimide resin according to any one of the above items. <16> The above <15> A circuit board having the laminate described in 1. <17> The above <16> 10 is an antenna having the circuit board according to claim 19. <18> The antenna according to claim 17 is a millimeter wave antenna. <19> consisting of an acid anhydride and a diamine, The acid anhydride is at least one compound selected from the group consisting of compounds represented by the following general formula (A-1): The polyamic acid for high-frequency substrate materials is such that the diamine is at least one selected from the group consisting of compounds represented by the following general formula (B-1) and compounds represented by the following general formula (B-2): [ka] In the general formula (A-1), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; l represents an integer of 0 to 3, and when l is 0, it represents that there is no bond; m represents an integer of 0 to 3; n represents an integer of 0 to 5, If n is 0, then at least one R 1 has a fluorine atom, R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 2 may be bonded to each other to form a cycloalkyl group, At least one R 2 represents a fluoroalkyl group which may have a substituent, Each X is independently -O-, -C(R 3 )2-, and -SO2-; R 3 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 3 may be bonded to each other to form a cycloalkyl group. [ka] In the general formula (B-1), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; l represents an integer of 1 to 3, m represents an integer of 0 to 3; n represents an integer of 0 to 5, o represents an integer from 0 to the maximum number of substituents; R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 2 may be bonded to each other to form a cycloalkyl group, At least one R 2 represents a fluoroalkyl group which may have a substituent, Each X is independently -O-, -C(R 3 )2-, and -SO2-; R 3 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 3 may be bonded to each other to form a cycloalkyl group. [ka] In the general formula (B-2), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; At least one R 1 has a fluorine atom, m's each independently represent an integer of 0 to 2, o represents an integer from 0 to the maximum number of substituents. <20> consisting of an acid anhydride and a diamine, The acid anhydride is at least one selected from the group consisting of compounds represented by the following general formulas (A-2a) to (A-2g): The polyamic acid for use in high-frequency substrate materials is such that the diamine is at least one selected from the group consisting of compounds represented by the following general formula (B-3) and compounds represented by the following general formula (B-4): [ka] In the general formulas (A-2a) to (A-2g), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; l represents an integer of 1 to 3, R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. [ka] In the general formula (B-3), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; l represents an integer of 1 to 3, m represents an integer of 0 to 3; n represents an integer of 0 to 5, o represents an integer from 0 to the maximum number of substituents; R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; At least one R 2represents a fluoroalkyl group which may have a substituent, Each X is independently -O-, -C(R 3 )2-, and -SO2-; R 3 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 3 may be bonded to each other to form a cycloalkyl group. [ka] In the general formula (B-4), R 1 are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; m's each independently represent an integer of 0 to 2, o represents an integer from 0 to the maximum number of substituents. <21> The above <19> or <20> and a solvent. [Effects of the Invention]

[0006] According to the present disclosure, it is possible to provide a polyimide resin for use as a high-frequency substrate material that has both a low dielectric constant and a low coefficient of linear expansion. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view showing an example of the laminate of this embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing another example of the laminate of the present embodiment. [Figure 3] FIG. 3 is a graph plotting the free volume fraction and the average number of adjacent atoms in the molecular dynamics simulation of the example. [Figure 4]FIG. 4 is a graph plotting the measured values ​​of the dielectric constant and the measured values ​​of the linear expansion coefficient. [Figure 5] FIG. 5 is a graph showing the relationship between experimental values ​​and calculated values ​​of molecular dynamics simulation for the dielectric constant at a frequency of 10 GHz. [Figure 6] FIG. 6 is a graph showing the relationship between experimental values ​​of the linear expansion coefficient and values ​​calculated by molecular dynamics simulation. DETAILED DESCRIPTION OF THE INVENTION

[0008] (Polyimide resin for high frequency circuit board materials) The polyimide resin for high-frequency substrate materials of the present disclosure is a polyimide resin used in applications as a material for high-frequency substrates, which has both a low dielectric constant and a low linear expansion coefficient, and which (1) has a specific chemical structure in a first embodiment, (2) has a specific chemical structure in a second embodiment, (3) satisfies the specifications for the free volume fraction and the average number of adjacent atoms in a third embodiment, or (4) satisfies (1) or (2) and (3). Here, "high frequency" refers to a high frequency band of 10 GHz or higher, a frequency band of 30 GHz to 300 GHz known as millimeter waves (radio wave wavelength of 1 mm to 10 mm), or a frequency band of 24.25 GHz to 52.6 GHz compatible with fifth-generation mobile communication systems (5G), any of which can be selected appropriately depending on the intended use. The polyimide resin preferably has a dielectric constant of 2.6 or less at 10 GHz and a linear expansion coefficient of 50 ppm / K or less.

[0009] The polyimide resin for use as a high-frequency substrate material according to the present disclosure is based on the following findings made by the present inventors. In other words, while a low dielectric constant and a low linear expansion coefficient have generally been in a trade-off relationship, making it difficult to achieve both, the present inventors, as shown in the Examples below, have identified two parameters, "free volume fraction" and a newly defined "average number of adjacent atoms," through molecular dynamics simulations using amorphous polyimide resins, and found that the two parameters correlate with the calculated values ​​of the dielectric constant and linear expansion coefficient. In addition, as a result of evaluating the relationships between the experimental values ​​of the dielectric constant and linear expansion coefficient for many known polyimide resins, they have found that a high "free volume fraction" contributes to a low dielectric constant and a low linear expansion coefficient, and that a low "average number of adjacent atoms" contributes to a low dielectric constant. From this, we found that the free volume fraction and the average number of adjacent atoms can be used as indicators to identify polyimide resins that have both a low dielectric constant and a low linear expansion coefficient. Furthermore, by the molecular dynamics simulation, we identified the chemical structure of polyimide resins that have both a low dielectric constant and a low linear expansion coefficient.

[0010] [First embodiment] A polyimide resin for use as a high-frequency substrate material in a first embodiment of the present disclosure is a polyimide resin comprising an acid anhydride and a diamine, wherein the acid anhydride is one or more compounds selected from the group consisting of compounds represented by the following general formula (A-1), and the diamine is one or more compounds selected from the group consisting of compounds represented by the following general formula (B-1) and compounds represented by the following general formula (B-2):

[0011] <Acid anhydride> The acid anhydride is at least one selected from the group consisting of compounds represented by the following general formula (A-1). In one embodiment, it is preferably one or more compounds selected from the group consisting of compounds represented by the following general formula (A-1a) and compounds represented by any one of the following general formulas (A-1b). The acid anhydrides may be used alone or in combination of two or more.

[0012] [ka]

[0013] In the general formula (A-1), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent.

[0014] The substituent may be any group having a structure that can be substituted on the target, and examples thereof include one or more groups selected from the group consisting of halogen, a hydroxy group, an alkoxy group, an alkylcarbonyl group, an alkylcarbonyloxy group, an alkoxycarbonyl group, an arylcarbonyloxy group, an aryloxycarbonyl group, and an aryl group. The number of the substituents can be selected from integers (for example, 1, 2, 3, etc.) within the range of 1 to the maximum number of substituents that can be substituted (hereinafter referred to as the "maximum number of substituents").

[0015] R 1 are each independently preferably selected from the group consisting of hydrogen, fluorine, an alkyl group having 1 to 4 carbon atoms, and a fluoroalkyl group having 1 to 4 carbon atoms, and more preferably selected from the group consisting of hydrogen, fluorine, a methyl group (-CH3), and a trifluoromethyl group (-CF3). Also, when n=0, at least one of the R 1 has a fluorine atom. When n=0, one of the R 1 is fluorine, and the other R 1 are each independently selected from the group consisting of hydrogen, fluorine, an alkyl group having 1 to 4 carbon atoms, and a fluoroalkyl group having 1 to 4 carbon atoms; 1 is fluorine, and the other R 1 are each independently selected from the group consisting of hydrogen, fluorine, a methyl group, and a trifluoromethyl group.

[0016] In the general formula (A-1), l represents an integer of 0 to 3. When l is 0, it indicates that there is no bond, and l is preferably 0, 1 or 2, and more preferably 0 or 1. m represents an integer of 0 to 3, preferably 0, 1 or 2, and more preferably 0 or 1. n represents an integer of 0 to 5, preferably an integer of 0 to 3, and more preferably 0 or 1.

[0017] In the general formula (A-1), R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 2 may be bonded to each other to form a cycloalkyl group, and at least one R 2 is a fluoroalkyl group which may have a substituent. R 2 The substituents in the above R 1 The substituents described above can be appropriately selected, but halogens other than fluoro and alkyl groups having 1 to 4 carbon atoms are preferred. One of the R 2 is a fluoroalkyl group having 1 to 4 carbon atoms, and the other R 2 are each independently selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, and an aromatic ring; 1 is a trifluoromethyl group, and the other R 1 are each independently selected from the group consisting of hydrogen, a methyl group, a trifluoromethyl group, and a phenyl group.

[0018] In the general formula (A-1), each X is independently —O—, —C(R 3 )2-, and -SO2-.

[0019] In the general formula (A-1), R 3are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 3 may be bonded to each other to form a cycloalkyl group. R 3 The substituents in the above R 1 The substituents described above can be appropriately selected. R 3 is more preferably each independently selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0020] In one embodiment, the general formula (A-1) is preferably either the following general formula (A-1a) or the following general formula (A-1b). The following general formula (A-1a) is one embodiment of the general formula (A-1) where n=0. The following general formula (A-1b) is one embodiment of the general formula (A-1) where l=0 and m=0.

[0021] [ka]

[0022] In the general formula (A-1a), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and at least one R 1 has a fluorine atom. One of the R 1 is fluorine, and the other R 1 are each independently selected from the group consisting of hydrogen, fluorine, and an alkyl group having 1 to 4 carbon atoms; 1 is fluorine, and the other R 1 are each independently selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0023] In the general formula (A-1a), m represents an integer of 0 to 3, and is preferably 0, 1 or 2, and more preferably 0 or 1.

[0024] [ka]

[0025] In the general formula (A-1b), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. R 1 is preferably each independently selected from the group consisting of hydrogen, fluorine, and an alkyl group having 1 to 4 carbon atoms, and more preferably selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0026] In the general formula (A-1b), n represents an integer of 1 to 5, preferably an integer of 1 to 3, and more preferably 1.

[0027] In the general formula (A-1b), R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 2 may be bonded to each other to form a cycloalkyl group, and at least one R 2 is a fluoroalkyl group which may have a substituent. One of the R 2 is a fluoroalkyl group having 1 to 4 carbon atoms, and the other R 2 are each independently selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, and an aromatic ring; 1 is a trifluoromethyl group, and the other R 1 are each independently selected from the group consisting of hydrogen, a methyl group, a trifluoromethyl group, and a phenyl group.

[0028] In the general formula (A-1b), each X is independently —O—, —C(R 3 )2-, and -SO2-.

[0029] In the general formula (A-1b), R 3 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 3 may be bonded to each other to form a cycloalkyl group. R 3 is more preferably each independently selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0030] <Diamine> The diamine is at least one selected from the group consisting of compounds represented by the following general formula (B-1) and compounds represented by the following general formula (B-2). In one embodiment, the general formula (B-1) is preferably either the following general formula (B-1a) or the following general formula (B-1b), and the general formula (B-2) is preferably the following general formula (B-2a). The diamines may be used alone or in combination of two or more.

[0031] [ka]

[0032] In the general formula (B-1), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. R in the general formula (B-1) 1 The substituent in the formula (A-1) is R 1 The substituents described above can be appropriately selected. R 1 is preferably each independently selected from the group consisting of hydrogen, fluorine, and an alkyl group having 1 to 4 carbon atoms, and more preferably selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0033] In the general formula (B-1), l represents an integer of 1 to 3, preferably 1 or 2, and more preferably 1. m represents an integer of 0 to 3, preferably 0, 1 or 2, and more preferably 0 or 1. n represents an integer of 0 to 5, preferably an integer of 0 to 3, and more preferably 0 or 1. o represents an integer of 0 to the maximum number of substituents, and is preferably an integer of 25% or more of the maximum number of substituents, and more preferably an integer of 50% or more of the maximum number of substituents.

[0034] In the general formula (B-1), R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 2 may be bonded to each other to form a cycloalkyl group, and at least one R 2 is a fluoroalkyl group which may have a substituent. R in the general formula (B-1) 2 The substituent in the formula (A-1) is R 1 The substituents described above can be appropriately selected, but halogens other than fluoro and alkyl groups having 1 to 4 carbon atoms are preferred. One of the R 2 is a fluoroalkyl group having 1 to 4 carbon atoms, and the other R 2 are each independently selected from the group consisting of hydrogen, an alkyl group having 1 to 4 carbon atoms, and an aromatic ring; 1 is a trifluoromethyl group, and the other R 1are each independently selected from the group consisting of hydrogen, a methyl group, a trifluoromethyl group, and a phenyl group.

[0035] In the general formula (B-1), each X is independently —O—, —C(R 3 )2-, and -SO2-.

[0036] In the general formula (B-1), R 3 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 3 may be bonded to each other to form a cycloalkyl group. R in the general formula (B-1) 3 The substituent in the formula (A-1) is R 1 The substituents described above can be appropriately selected. R 3 is more preferably each independently selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0037] The diamine, which is a compound represented by the general formula (B-1), has two amino groups (—NH2). When m is 0, the two amino groups can be substituted at any two positions on the benzene ring shown at the left end of the general formula (B-1), and when m is 1, 2, or 3, the two amino groups can be substituted at any two positions on the fused benzene ring.

[0038] [ka]

[0039] In the general formula (B-2), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and at least one R1 has a fluorine atom. R in the general formula (B-2) 1 The substituent in the formula (A-1) is R 1 The substituents described above can be appropriately selected. One of the R 1 is fluorine, and the other R 1 are each independently selected from the group consisting of hydrogen, fluorine, and an alkyl group having 1 to 4 carbon atoms; 1 is fluorine, and the other R 1 are each independently selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0040] In the general formula (B-2), each m independently represents an integer of 0 to 2, preferably 0 or 1, and more preferably 0. o represents an integer of 0 to the maximum number of substituents, and is preferably an integer of 25% or more of the maximum number of substituents, and more preferably an integer of 50% or more of the maximum number of substituents.

[0041] The diamine, which is a compound represented by the general formula (B-2), has two amino groups (-NH2). When m is 0, the two amino groups can be substituted at any two positions on the benzene rings shown at both ends of the general formula (B-2), and they can be substituted on the same benzene ring or on each of the two benzene rings.When m is 1 or 2, the two amino groups can be substituted at any two positions on the two fused benzene rings, and they can be substituted on the same fused benzene ring or on each of the two fused benzene rings.

[0042] In one embodiment, the general formula (B-1) is preferably either the following general formula (B-1a) or the following general formula (B-1b), and the general formula (B-2) is preferably the following general formula (B-2a). The following general formula (B-1a) is one embodiment of the general formula (B-1) where m=0 and n=0. The following general formula (B-1b) is one embodiment of the general formula (B-1) where n=0. The following general formula (B-2a) is one embodiment of the general formula (B-2) where m=0.

[0043] [ka]

[0044] In the general formula (B-1a), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. R 1 is preferably each independently selected from the group consisting of fluorine and an alkyl group having 1 to 4 carbon atoms, and more preferably selected from the group consisting of fluorine and a methyl group.

[0045] In the general formula (B-1a), o represents an integer of 0 to 4, preferably an integer of 1 to 4, and more preferably an integer of 2 to 4.

[0046] [ka]

[0047] In the general formula (B-1b), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. R 1 is preferably each independently selected from the group consisting of hydrogen, fluorine, and an alkyl group having 1 to 4 carbon atoms, and more preferably selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0048] In the general formula (B-1b), m represents an integer of 1 to 3, preferably 1 or 2, and more preferably 1. o represents an integer of 0 to the maximum number of substituents, and is preferably an integer of 25% or more of the maximum number of substituents, and more preferably an integer of 50% or more of the maximum number of substituents.

[0049] [ka]

[0050] In the general formula (B-2a), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and at least one R 1 has a fluorine atom. One of the R 1 is fluorine, and the other R 1 are each independently selected from the group consisting of hydrogen, fluorine, and an alkyl group having 1 to 4 carbon atoms; 1 is fluorine, and the other R 1 are each independently selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0051] In the general formula (B-2a), o represents an integer of 0 to 8, preferably an integer of 2 to 8, and more preferably an integer of 4 to 8.

[0052] [Second embodiment] A polyimide resin for use as a high-frequency substrate material in a second embodiment of the present disclosure is a polyimide resin comprising an acid anhydride and a diamine, wherein the acid anhydride is one or more compounds selected from the group consisting of compounds represented by the following general formulas (A-2a) to (A-2g), and the diamine is one or more compounds selected from the group consisting of compounds represented by the following general formula (B-3) and compounds represented by the following general formula (B-4):

[0053] <Acid anhydride> The acid anhydride is at least one selected from the group consisting of compounds represented by the following general formulas (A-2a) to (A-2g). The acid anhydrides may be used alone or in combination of two or more.

[0054] [ka]

[0055] In the general formulas (A-2a) to (A-2g), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. R in the general formulae (A-2a) to (A-2g) 1 The substituent in the formula (A-1) is R 1 The substituents described above can be appropriately selected. R 1 are each independently preferably selected from the group consisting of hydrogen, fluorine, an alkyl group having 1 to 4 carbon atoms, and a fluoroalkyl group having 1 to 4 carbon atoms, and more preferably selected from the group consisting of hydrogen, fluorine, a methyl group, and a trifluoromethyl group.

[0056] In the general formulae (A-2a) to (A-2g), l represents an integer of 1 to 3, and is preferably 1 or 2.

[0057] In the general formulas (A-2a) to (A-2g), R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. R in the general formulae (A-2a) to (A-2g) 2 The substituent in the formula (A-1) is R 1 The substituents described above can be appropriately selected. R 2 are each independently preferably selected from the group consisting of hydrogen, fluorine, an alkyl group having 1 to 4 carbon atoms, and a fluoroalkyl group having 1 to 4 carbon atoms, and more preferably selected from the group consisting of hydrogen, fluorine, a methyl group, and a trifluoromethyl group.

[0058] <Diamine> The diamine is at least one selected from the group consisting of compounds represented by the following general formula (B-3) and compounds represented by the following general formula (B-4). In one embodiment, the general formula (B-3) is preferably either the following general formula (B-3a) or the following general formula (B-3b), and the general formula (B-4) is preferably the following general formula (B-4a). The diamines may be used alone or in combination of two or more.

[0059] [ka]

[0060] In the general formula (B-3), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. R in the general formula (B-3) 1 The substituent in the formula (A-1) is R 1The substituents described above can be appropriately selected. R 1 is preferably each independently selected from the group consisting of hydrogen, fluorine, and an alkyl group having 1 to 4 carbon atoms, and more preferably selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0061] In the general formula (B-3), l represents an integer of 1 to 3, preferably 1 or 2, and more preferably 1. m represents an integer of 0 to 3, preferably 0, 1 or 2, and more preferably 0 or 1. n represents an integer of 0 to 5, preferably an integer of 0 to 3, and more preferably 0 or 1. o represents an integer of 0 to the maximum number of substituents, and is preferably an integer of 25% or more of the maximum number of substituents, and more preferably an integer of 50% or more of the maximum number of substituents.

[0062] In the general formula (B-3), R 2 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and at least one R 2 is a fluoroalkyl group which may have a substituent. R in the general formula (B-3) 2 The substituent in the formula (A-1) is R 1 The substituents described above can be appropriately selected. One of the R 2 is a fluoroalkyl group having 1 to 4 carbon atoms, and the other R 2 are each independently selected from the group consisting of hydrogen, fluorine, an alkyl group having 1 to 4 carbon atoms, and an aromatic ring; 1 is a trifluoromethyl group, and the other R 1 are each independently selected from the group consisting of hydrogen, a methyl group, a trifluoromethyl group, and a phenyl group.

[0063] In the general formula (B-3), each X is independently —O—, —C(R 3 )2-, and -SO2-.

[0064] In the general formula (B-3), R 3 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R 3 may be bonded to each other to form a cycloalkyl group. R in the general formula (B-3) 3 The substituent in the formula (A-1) is R 1 The substituents described above can be appropriately selected. R 3 is more preferably each independently selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0065] [ka]

[0066] In the general formula (B-4), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. R in the general formula (B-4) 1 The substituent in the formula (A-1) is R 1 The substituents described above can be appropriately selected. R 1 is preferably each independently selected from the group consisting of hydrogen, fluorine, and an alkyl group having 1 to 4 carbon atoms, and more preferably selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0067] In the general formula (B-4), each m independently represents an integer of 0 to 2, preferably 0 or 1, and more preferably 0. o represents an integer of 0 to the maximum number of substituents, and is preferably an integer of 25% or more of the maximum number of substituents, and more preferably an integer of 50% or more of the maximum number of substituents.

[0068] In one embodiment, the general formula (B-3) is preferably either the following general formula (B-3a) or the following general formula (B-3b), and the general formula (B-4) is preferably the following general formula (B-4a). The following general formula (B-3a) is one embodiment of the general formula (B-3) where m=0 and n=0. The following general formula (B-3b) is one embodiment of the general formula (B-3) where n=0. The following general formula (B-4a) is one embodiment of the general formula (B-4) where m=0.

[0069] [ka]

[0070] In the general formula (B-3a), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. R 1 is preferably each independently selected from the group consisting of fluorine and an alkyl group having 1 to 4 carbon atoms, and more preferably selected from the group consisting of fluorine and a methyl group.

[0071] In the general formula (B-3a), o represents an integer of 0 to 4, preferably an integer of 1 to 4, and more preferably an integer of 2 to 4.

[0072] [ka]

[0073] In the general formula (B-3b), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. R 1 is preferably each independently selected from the group consisting of hydrogen, fluorine, and an alkyl group having 1 to 4 carbon atoms, and more preferably selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0074] In the general formula (B-3b), m represents an integer of 1 to 3, preferably 1 or 2, and more preferably 1. o represents an integer of 0 to the maximum number of substituents, and is preferably an integer of 25% or more of the maximum number of substituents, and more preferably an integer of 50% or more of the maximum number of substituents.

[0075] [ka]

[0076] In the general formula (B-4a), R 1 are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and at least one R 1 has a fluorine atom. One of the R 1 is fluorine, and the other R 1 are each independently selected from the group consisting of hydrogen, fluorine, and an alkyl group having 1 to 4 carbon atoms; 1 is fluorine, and the other R 1 are each independently selected from the group consisting of hydrogen, fluorine, and a methyl group.

[0077] In the general formula (B-4a), o represents an integer of 0 to 8, preferably an integer of 2 to 8, and more preferably an integer of 4 to 8.

[0078] [Third embodiment] A polyimide resin for use as a high-frequency substrate material in a third embodiment of the present disclosure is a polyimide resin having a structural unit represented by the following general formula (1): [ka] In the general formula (1), R a The (CO)4 moiety represents a tetravalent group derived from a tetravalent tetracarboxylic acid having two or more carbon atoms, and R b The (N)2 moiety represents a tetravalent group derived from a divalent diamine having two or more carbon atoms. The free volume fraction and the average number of adjacent atoms of the amorphous polyimide resin in an equilibrium state at a temperature of 300 K and a pressure of 1 atm, as calculated by molecular dynamics calculation, satisfy the following condition (1) or (2): (1) The free volume fraction is 0.23 to 0.38, and the average number of adjacent atoms is 3.80 to 4.75, or (2) the free volume fraction is 0.24 to 0.38, and the average number of adjacent atoms is 3.94 to 4.95; the average number of adjacent atoms is an average of the number of adjacent atoms per number of atoms constituting the system of the molecular dynamics calculation, The polyimide resin for use as a high-frequency substrate material is such that the number of adjacent atoms is the total number of atom pairs that satisfies the following conditions (a) and (b): (a) Atomic pairs that share one edge of a Voronoi cell with each atom as a kernel point (b) Atom pairs separated by four or more bonds, or atom pairs between different molecules

[0079] -Free volume fraction- "Free volume" is the volume per unit mass of a molecule at a constant temperature and pressure, i.e., the specific volume v, minus the occupied volume v0 of that molecule, and can be expressed as the free volume vf using the following equation 1. Furthermore, the "free volume fraction" is the free volume vf per specific volume v, and can be expressed as the free volume fraction f by the following formula 2. (Formula 1) vf=v-v0 (Formula 2) f=(v-v0) / v

[0080] The free volume fraction in this embodiment is the free volume fraction of the amorphous polyimide resin in an equilibrium state at a temperature of 300 K and a pressure of 1 atm, calculated by molecular dynamics calculation, and can be calculated by the following formula 3. Specifically, the free volume fraction can be calculated using the polymer property automatic calculation system RadonPy (open source software) and a Python library molecular dynamics calculation, and the free volume fraction f can be calculated by the following formula 3 based on the coordinates of each atom in an equilibrium state in a molecular dynamics simulation described later. The van der Waals radius of each atom in the following formula 3 was calculated based on the GAFF2 force field (Reference 1 below). Reference 1: X. He, VH Man, W. Yang, T.-S. Lee, and J. Wang, A Fast and High-Quality Charge Model for the next Generation General AMBER Force Field, J. Chem. Phys. 153, 114502 (2020).

[0081] (Formula 3)

number

[0082] -Average number of adjacent atoms- The average number of adjacent atoms is the average number of adjacent atoms per number of atoms constituting the system of the molecular dynamics calculation. The number of adjacent atoms is the total number of atom pairs that satisfy the following conditions (a) and (b): (a) Atomic pairs that share one edge of a Voronoi cell with each atom as a kernel point (b) Atom pairs separated by four or more bonds, or atom pairs between different molecules

[0083] Specifically, the number of adjacent atoms is calculated by molecular dynamics calculation as the total number of atom pairs that satisfy the following (a) and (b): (a) In a Voronoi diagram calculated with each atom as a kernel point, atom pairs (pairs of kernel points) that share a Voronoi edge (b) Atom pairs separated by four or more bonds, or atom pairs between different molecules The average number of adjacent atoms can be calculated by dividing the total number of pairs (i.e., the number of adjacent atoms) that satisfy (a) and (b) in a system with periodic boundary conditions by the number of atoms that make up the system.

[0084] The average number of adjacent atoms in this embodiment is the average number of adjacent atoms calculated by molecular dynamics calculation in an equilibrium state of the polyimide resin in an amorphous state at a temperature of 300 K and a pressure of 1 atm. The average number of adjacent atoms per atom can be calculated by performing Voronoi polyhedron analysis with each atom as a kernel point based on the coordinates of each atom in the equilibrium state in a molecular dynamics simulation described below, and dividing the total number of atom pairs in the amorphous cell that satisfy (a) and (b) by the total number of atoms constituting the amorphous cell.

[0085] The free volume fraction and the average number of adjacent atoms preferably satisfy the following condition (1) or (2), and also satisfy any one of the following conditions (3) to (6). According to the molecular dynamics simulation described below, when the following condition (1) or (2) is satisfied, it is possible to achieve both a low dielectric constant of 2.6 or less at 10 GHz and a low linear expansion coefficient of 50 ppm / K or less. (1) The free volume fraction is 0.23 to 0.38, and the average number of adjacent atoms is 3.80 to 4.75, or (2) The free volume fraction is 0.24 to 0.38, and the average number of adjacent atoms is 3.94 to 4.95.

[0086] (3) The free volume fraction is 0.23 to 0.32, and the average number of adjacent atoms is 3.90 to 4.60. When the condition (3) is satisfied, the dielectric constant at 10 GHz is 2.5 or less, and the linear expansion coefficient is 40 ppm / K or less, so that both a low dielectric constant and a low linear expansion coefficient can be achieved.

[0087] (4) The free volume fraction is 0.23 to 0.32, the average number of adjacent atoms is 3.90 to 4.60, and the polymer does not have a trifluoromethyl group. When the condition (4) is satisfied, it is possible to achieve both a low dielectric constant of 2.5 or less at 10 GHz and a low linear expansion coefficient of 40 ppm / K or less.

[0088] (5) The free volume fraction is 0.24 to 0.32, the average number of adjacent atoms is 3.90 to 4.50, and the polymer does not have a trifluoromethyl group. When the condition (5) is satisfied, it is possible to achieve both a low dielectric constant of 2.5 or less at 10 GHz and a low linear expansion coefficient of 30 ppm / K or less.

[0089] (6) The free volume fraction is 0.28 to 0.32, the average number of adjacent atoms is 3.90 to 4.50, and the polymer does not have a trifluoromethyl group. When the condition (6) is satisfied, it is possible to achieve both a low dielectric constant of 2.5 or less at 10 GHz and a low linear expansion coefficient of 20 ppm / K or less.

[0090] [Fourth embodiment] The polyimide resin for a high-frequency board material in the fourth embodiment of the present disclosure is the polyimide resin for a high-frequency board material in the first embodiment or the polyimide resin for a high-frequency board material in the second embodiment, The free volume fraction and the average number of adjacent atoms of the amorphous polyimide resin in an equilibrium state at a temperature of 300 K and a pressure of 1 atm, as calculated by molecular dynamics calculation, satisfy the following condition (1) or (2): (1) The free volume fraction is 0.23 to 0.38, and the average number of adjacent atoms is 3.80 to 4.75, or (2) the free volume fraction is 0.24 to 0.38, and the average number of adjacent atoms is 3.94 to 4.95; the average number of adjacent atoms is an average of the number of adjacent atoms per number of atoms constituting the system of the molecular dynamics calculation, The polyimide resin for use as a high-frequency substrate material is such that the number of adjacent atoms is the total number of atom pairs that satisfies the following conditions (a) and (b): (a) Atomic pairs that share one edge of a Voronoi cell with each atom as a kernel point (b) Atom pairs separated by four or more bonds, or atom pairs between different molecules

[0091] The polyimide resin for the high-frequency substrate material in the first embodiment and the polyimide resin for the high-frequency substrate material in the second embodiment can be appropriately selected from the items described in the first embodiment and the second embodiment, respectively. The conditions for the free volume fraction and the average number of adjacent atoms can be appropriately selected from those described in the third embodiment. The free volume fraction and the average number of adjacent atoms preferably satisfy the condition (1) or (2) and any one of the conditions (3) to (6).

[0092] [Characteristics] Each of the polyimide resins for high frequency substrate materials in the first to fourth embodiments preferably has a dielectric constant of 2.6 or less at 10 GHz and a linear expansion coefficient of 50 ppm / K or less.

[0093] -Dielectric constant- The dielectric constant of the polyimide resin at 10 GHz is preferably 2.6 or less, more preferably 2.5 or less, and even more preferably 2.4 or less.

[0094] Specifically, the dielectric constant of the polyimide resin at 10 GHz can be measured by the SPDR method (resonator method) using a vector network analyzer (E5063A, manufactured by Keysight Corporation) for a polyimide film obtained by the polyimide film manufacturing method described below. Note that the polyimide film used as a measurement sample is left to stand at a temperature of 23±1°C and a humidity of 50±5% RH for 24 hours or more before use.

[0095] Furthermore, as a method for calculating the dielectric constant of the polyimide resin at 10 GHz by molecular dynamics simulation, the following procedure can be specifically mentioned, as will be explained in the molecular dynamics simulation described later.

[0096] Using molecular dynamics calculations, the length of the dielectric relaxation function (e.g., 100 ns) and the time length for calculating the dipole moment (e.g., 500 ns) are set, and the dipole moment of the target substance is calculated, generating time-series data of the dipole moment. Next, a high-pass filter is designed based on the received calculation conditions. The cutoff frequency of the high-pass filter is the inverse of the length of the dielectric relaxation function. If the length of the dielectric relaxation function is 100 ns, the cutoff frequency is 10 MHz. Next, the designed high-pass filter is used to remove low-frequency components from the dipole moment time series data. In other words, the frequency band above the cutoff frequency is extracted from the dipole moment time series data. This generates filtered dipole moment time series data from which low-frequency components (e.g., below 10 GHz) have been removed.

[0097] Next, the time series data of the dipole moment after filtering is defined as M(t), and the dielectric relaxation function Φ(t) is calculated using equation (1). The calculated dielectric relaxation function Φ(t) is fitted using equation (2). Furthermore, the dielectric relaxation function Φ after fitting is obtained by Fourier transform of equation (3). fit (t) is frequency resolved, which gives the frequency-dependent complex permittivity, and the permittivity at a frequency of 10 GHz can be calculated from the real part of the complex permittivity at a frequency of 10 GHz.

[0098] Here, by removing low-frequency components (e.g., less than 10 GHz) that are susceptible to local effects in the simulation from the time-series data of the dipole moment, the dielectric relaxation function of the target material, polyimide resin, can be derived with high accuracy.

[0099]

number

[0100]

number

[0101]

number

[0102] -Linear expansion coefficient- The coefficient of linear expansion means the ratio of the amount of deformation ΔL per 1 K (Kelvin) or 1°C of temperature change to the original length L. The linear expansion coefficient of the polyimide resin is preferably 50 ppm / K or less, more preferably 40 ppm / K or less, even more preferably 30 ppm / K or less, and particularly preferably 20 ppm / K or less.

[0103] Specifically, the linear expansion coefficient of the polyimide resin can be measured for a polyimide film obtained by the polyimide film manufacturing method described below using a thermomechanical analyzer (EXSTAR6000TMA / SS6000, manufactured by SII NanoTechnology Inc.) under the following measurement conditions. --Measurement conditions-- First stage: The temperature is increased to 150°C at a rate of 5°C / min to remove adsorbed water from the sample. Second stage: Air-cool to room temperature at a rate of 5°C / min. Third step: The actual measurement is carried out at a temperature increase rate of 5°C / min. The average value of the linear expansion coefficients in the temperature range of 50°C to 200°C in this measurement is determined and is used as the linear expansion coefficient of the target polyimide film.

[0104] Furthermore, as a method for calculating the linear expansion coefficient of the polyimide resin by molecular dynamics simulation, the following procedure can be specifically mentioned, as will be explained in the molecular dynamics simulation described later. First, based on the fluctuations of volume V and enthalpy H in the equilibrium calculation, the volume expansion rate α is calculated using the following formula: P Calculate [see Reference 2 below]. B is the Boltzmann constant, and T is the temperature. Reference 2: MP Allen and DJ Tildesley, Computer Simulation of Liquids (Clarendon Press, New York, 1989).

[0105]

number

[0106] Next, assuming the system is isotropic, the linear expansion coefficient α L is derived.

[0107]

number

[0108] -Dielectric loss tangent- The dielectric loss tangent of the polyimide resin is preferably 0.0040 or less, more preferably 0.0035 or less, and even more preferably 0.0030 or less. Since the dielectric loss is proportional to the product of the square root of the dielectric constant and the dielectric loss tangent, a dielectric loss tangent of 0.0040 or less can effectively reduce the dielectric loss.

[0109] Specifically, the dielectric loss tangent of the polyimide resin can be measured by the SPDR method (resonator method) at a frequency of 1 GHz or 10 GHz using a vector network analyzer (E5063A, manufactured by Keysight Corporation) for a polyimide film obtained by the polyimide film manufacturing method described below. Note that the polyimide film used as a measurement sample is left to stand at a temperature of 23±1°C and a humidity of 50±5% RH for 24 hours or more before use.

[0110] -Glass transition temperature- The glass transition temperature of the polyimide resin is preferably 260°C or higher, more preferably 280°C or higher, and even more preferably 300°C or higher. If the glass transition temperature is 260° C. or higher, the material can be used as a material for high frequency substrates having good solder heat resistance and dimensional stability.

[0111] -Hayes- The haze of the polyimide resin is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. When the haze is 20% or less, the alignment marks can be easily recognized in the photolithography process when the laminate is made and in the subsequent mounting process of the high frequency board, and the laminate can be suitably used.

[0112] Specifically, the haze of the polyimide resin can be measured using a spectroscopic haze meter (HSP-150Vis, manufactured by Murakami Color Research Laboratory Co., Ltd.) for a polyimide film obtained by the polyimide film manufacturing method described below. The average thickness of the polyimide film to be measured is preferably 5 μm or more and 80 μm or less.

[0113] -Breaking elongation- The breaking elongation of the polyimide resin is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more. When the breaking elongation is 20% or more, the polyimide film is less likely to break during transport in the production process, maintaining good productivity. Furthermore, when made into a flexible printed circuit board, the bending resistance is maintained and cracks and disconnections of wiring during the mounting process are less likely to occur.

[0114] -Tensile modulus- The tensile modulus of elasticity of the polyimide resin is preferably 5 GPa or more, more preferably 6 GPa or more, and even more preferably 7 GPa or more. When the tensile modulus is 5 GPa or more, the amount of elongation of the film when tension is applied during film transport in the polyimide film production process is suppressed, and dimensional stability is maintained.

[0115] Specifically, the breaking elongation and tensile modulus of the polyimide resin can be measured by cutting a measurement sample into a strip of 10 mm width and 80 mm length from a polyimide film obtained by the polyimide film production method described below, using a Tensilon universal testing machine (RTM-100, manufactured by Orientec Co., Ltd.) in accordance with Japanese Industrial Standards (JIS K 7127:1999). The width of the measurement sample is 10 mm, the chuck interval is 50 mm, the test speed is 50 mm / min, and the number of measurements is n=10, and the average value is calculated.

[0116] [Method for synthesizing polyimide resin] The method for synthesizing the polyimide resin is not particularly limited, and any known method can be appropriately selected depending on the purpose. For example, equimolar amounts of an acid anhydride and a diamine are polymerized to synthesize a polyamic acid (polyamic acid), which is a precursor of polyimide, and the resulting polyamic acid is heated at a temperature of 200°C or higher or a catalyst is used to promote an imidization (dehydration and cyclization) reaction, thereby obtaining a polyimide. Instead of or in combination with the acid anhydride, a tetracarboxylic acid corresponding to the acid anhydride may be used. When a plurality of acid anhydrides and / or a plurality of diamines are used, the resulting polyamic acid and polyimide resin may be a random copolymer, a block copolymer, or a mixture of these.

[0117] The polyamic acid and the composition containing the polyamic acid can be synthesized, for example, by the following procedure. A thermometer and a stirring rod with stirring blades are placed in a 300 mL four-neck separable flask. Next, a solvent (e.g., dimethylacetamide, DMAC) is added under a dry nitrogen stream and the temperature is raised to 60°C. After the temperature is raised, diamine is added and dissolved while stirring. Next, an equimolar amount of acid anhydride is added and stirred to polymerize the acid anhydride and diamine. After that, the mixture is cooled to room temperature, and a solvent is added as needed, followed by filtration to obtain a composition containing polyamic acid.

[0118] The reaction temperature for polymerizing the acid anhydride and the diamine is preferably -20°C to 150°C, more preferably 0°C to 100°C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours. The number of moles of the acid anhydride and the diamine used in the reaction are preferably equal. The more nearly the amount of the acid anhydride and the diamine is equivalent in polyamic acid, the more likely it is that a polyimide film with excellent mechanical properties will be obtained.

[0119] The method for synthesizing the polyimide from the polyamic acid by the imidization reaction may be, for example, the following procedure. The resulting polyamic acid-containing composition is applied (e.g., spin-coated) onto a substrate, then dried (e.g., at 80°C for 5 minutes) using a hot plate, and subsequently heated at a temperature of 200°C or higher to form a polyimide resin film on the substrate. Examples of the method for heating at a temperature of 200°C or higher include a method in which, using an oven, the temperature is raised from 50°C at a rate of 4°C / min in a nitrogen atmosphere (oxygen concentration of 20 ppm or less), followed by heating at 180°C for 30 minutes and then heating at 350°C for 30 minutes.

[0120] [Polyimide resin identification method] The method for identifying the polyimide resin is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a method in which the polyimide resin is analyzed by infrared attenuated total reflection (IR-ATR) using a Fourier transform infrared spectrometer (FT-IR) to identify constituent components such as acid anhydrides and diamines. FT-IR can be measured using, for example, a Nicolet 6700 (manufactured by Thermo Fisher Scientific Co., Ltd.).

[0121] (Polyamic acid for high frequency circuit board materials) The polyamic acid for high-frequency substrate materials of the present disclosure is used in applications for high-frequency substrate materials and is a precursor of the polyimide resin for high-frequency substrate materials of the present disclosure, which has both a low dielectric constant and a low linear expansion coefficient, and is (1) a precursor of the polyimide resin for high-frequency substrate materials in the first embodiment, or (2) a polyamic acid that is a precursor of the polyimide resin for high-frequency substrate materials in the second embodiment.

[0122] [First embodiment] The polyamic acid for use as a high-frequency substrate material in the first embodiment of the present disclosure is a precursor of the polyimide resin for use as a high-frequency substrate material in the first embodiment, and is a polyamic acid comprising an acid anhydride and a diamine, wherein the acid anhydride is one or more compounds selected from the group consisting of compounds represented by general formula (A-1) above, and the diamine is one or more compounds selected from the group consisting of compounds represented by general formula (B-1) above and compounds represented by general formula (B-2).

[0123] The acid anhydride and diamine can be appropriately selected from those described in the polyimide resin for high frequency substrate materials in the first embodiment.

[0124] [Second embodiment] The polyamic acid for use as a high-frequency substrate material in the second embodiment of the present disclosure is a precursor of a polyimide resin for use as a high-frequency substrate material in the second embodiment, and is a polyamic acid comprising an acid anhydride and a diamine, wherein the acid anhydride is one or more compounds selected from the group consisting of compounds represented by the following general formulas (A-2a) to (A-2g), and the diamine is one or more compounds selected from the group consisting of compounds represented by the following general formula (B-3) and compounds represented by the following general formula (B-4):

[0125] The acid anhydride and diamine can be appropriately selected from those described in the polyimide resin for high frequency substrate materials in the second embodiment.

[0126] (Composition for high frequency substrate materials) [First embodiment] The composition for a high-frequency board material in the first embodiment of the present disclosure contains a polyimide resin, and may further contain other components such as a solvent, as necessary. Suitable examples of the polyimide resin include the polyimide resin for high-frequency board materials in the first embodiment, the polyimide resin for high-frequency board materials in the second embodiment, the polyimide resin for high-frequency board materials in the third embodiment, and the polyimide resin for high-frequency board materials in the fourth embodiment. These may be used alone or in combination of two or more. The composition for a high-frequency board material in the first embodiment can be suitably prepared by subjecting the composition for a high-frequency board material in the second embodiment to an imidization reaction.

[0127] [Second embodiment] The composition for a high-frequency board material in the second embodiment of the present disclosure contains a polyamic acid and a solvent, and may further contain other components as necessary. Suitable examples of the polyamic acid include the polyamic acid for high-frequency substrate materials in the first embodiment and the polyamic acid for high-frequency substrate materials in the second embodiment. These may be used alone or in combination of two or more.

[0128] <Solvent> The solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples of the solvent include water, N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethylisobutyramide, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, γ-butyrolactone, ethyl lactate, 1,3-dimethyl-2-imidazolidinone, N,N′-dimethylpropylene urea, 1,1,3,3-tetramethylurea, dimethyl sulfoxide, sulfolane, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol ethyl methyl ether, and diethylene glycol dimethyl ether. These may be used alone or in combination of two or more.

[0129] The content of the solvent is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 150 parts by mass or more, more preferably 200 parts by mass or more, relative to 100 parts by mass of the polyimide resin and / or polyamic acid in the composition, and is preferably 2000 parts by mass or less, more preferably 1000 parts by mass or less. When the content of the solvent is 150 parts by mass or more and 2000 parts by mass or less, the viscosity becomes suitable for coating, and the thickness of the composition after coating and the thickness of the obtained polyimide film can be easily adjusted.

[0130] <Other ingredients> Examples of the other components include a catalyst for catalyzing imidization and a dehydrating agent.

[0131] -catalyst- Examples of the catalyst include amines. Examples of the amines include aliphatic tertiary amines such as trimethylamine and triethylenediamine; aromatic tertiary amines such as dimethylaniline; and heterocyclic tertiary amines such as isoquinoline, pyridine, and β-picoline. These may be used alone or in combination of two or more. Among these, heterocyclic tertiary amines are preferred, and β-picoline is more preferred.

[0132] -Dehydrating agent- Examples of the dehydrating agent include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride; and aromatic carboxylic acid anhydrides such as benzoic anhydride. These may be used alone or in combination of two or more. Among these, acetic anhydride and benzoic anhydride are preferred, with acetic anhydride being more preferred.

[0133] The content of each of the catalyst and dehydrating agent is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 0.05 mol to 10 mol, more preferably 0.1 mol to 5 mol, and even more preferably 0.5 mol to 3 mol, per 1 mol of amic acid unit of the polyamic acid.

[0134] Furthermore, the composition for a high-frequency substrate material in the first embodiment may contain other components such as inorganic particles, a thermal crosslinking agent, a thermal acid generator, a leveling agent, a viscosity modifier, an antioxidant, an inorganic pigment, an organic pigment, or a dye.

[0135] -Inorganic particles- The composition for a high-frequency substrate material in the first embodiment and the polyimide film described later can contain inorganic particles for the purpose of further improving the heat resistance of the polyimide film and reducing the linear expansion coefficient. Examples of the inorganic particles include metal inorganic particles such as platinum, gold, palladium, silver, copper, nickel, zinc, aluminum, iron, cobalt, rhodium, ruthenium, tin, lead, bismuth, and tungsten; and metal oxide inorganic particles such as silicon oxide (silica), titanium oxide, aluminum oxide, zinc oxide, tin oxide, tungsten oxide, zirconium oxide, calcium carbonate, and barium sulfate. The shape and content of the inorganic particles are not particularly limited and can be appropriately selected depending on the purpose. Furthermore, it is preferable to uniformly disperse the inorganic particles in the composition and polyimide film, and known means can be used for this purpose.

[0136] (Polyimide film for high frequency circuit board materials) The polyimide film for use as a high-frequency substrate material according to the present disclosure contains a polyimide resin and may further contain other components as necessary. Suitable examples of the polyimide resin include the polyimide resin for high-frequency board materials in the first embodiment, the polyimide resin for high-frequency board materials in the second embodiment, the polyimide resin for high-frequency board materials in the third embodiment, and the polyimide resin for high-frequency board materials in the fourth embodiment. These may be used alone or in combination of two or more.

[0137] The average thickness of the polyimide film is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 3 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. If the average thickness is 3 μm or more, sufficient mechanical properties can be obtained as a circuit substrate. Furthermore, the average thickness is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 80 μm or less. If the average thickness is 80 μm or less, sufficient toughness can be obtained as a circuit substrate.

[0138] The polyimide film can be suitably used for films used in circuit boards such as flexible printed circuit boards, coverlay films, heat-resistant insulating tapes, heat-resistant adhesive tapes, high-density magnetic recording bases, capacitors, and the like.

[0139] [Polyimide film manufacturing method] The method for producing the polyimide film is not particularly limited and can be appropriately selected depending on the purpose. Examples include: (I) a production method comprising the steps of applying a composition containing polyamic acid onto a substrate and drying it, and heating the resulting coating film to imidize it; and (II) a production method comprising the steps of casting a composition containing polyamic acid onto a heated substrate, imidizing it to form a gel film, peeling the resulting gel film from the substrate, and heat-treating the peeled gel film.

[0140] The substrate is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include glass substrates; metal substrates such as stainless steel drums, endless stainless steel belts, and aluminum foils; and the like. The temperature of the substrate is preferably 30°C to 200°C, more preferably 40°C to 150°C, and even more preferably 50°C to 120°C. The drying temperature for the gel film is preferably 150°C to 500°C, more preferably 180°C to 400°C, and even more preferably 200°C to 300°C. The heat treatment temperature of the dried polyimide film is preferably 200°C or higher, more preferably 300°C or higher, and even more preferably 350°C or higher. The gel film and the polyimide film may be stretched in the machine direction or the width direction in each step.

[0141] The obtained polyimide film may further be subjected to annealing treatment or adhesion enhancing treatment (for example, electrical treatment such as corona treatment or plasma treatment, or blast treatment).

[0142] (Laminate) The laminate of the present disclosure has a metal layer and a layer containing a polyimide resin, and may further have other layers as necessary. The layer containing the polyimide resin is preferably the polyimide film of the present disclosure.

[0143] <Metal layer> The material for the metal layer is not particularly limited and can be appropriately selected depending on the purpose. Examples include copper or copper alloy, stainless steel or its alloy, nickel or nickel alloy, aluminum or aluminum alloy, and the like. Among these, copper and copper alloys are preferred, and copper alloys containing copper and one or more components selected from the group consisting of nickel, zinc, iron, chromium, cobalt, molybdenum, tungsten, vanadium, beryllium, titanium, tin, manganese, aluminum, phosphorus, and silicon are more preferred. The metal layer is preferably a metal foil formed by rolling or electrolytic plating, and more preferably a copper foil or a copper alloy foil.

[0144] The metal-clad laminate can be obtained by laminating the metal layer and the layer containing the polyimide resin. The metal layer can also have an anti-corrosion layer, a heat-resistant layer, a silane coupling agent, or the like formed on the surface of the metal layer.

[0145] The thickness of the metal layer is not particularly limited as long as it can perform its function adequately depending on the purpose. The surface of the metal layer is preferably smooth in order to reduce transmission loss, and preferably has an Ra of 1.0 μm or less.

[0146] As long as the laminate comprises the metal layer and the layer containing the polyimide resin, there are no limitations on the lamination form. For example, the polyimide film and the metal layer may be laminated directly, or the polyimide film and the metal layer may be laminated via an adhesive layer.

[0147] The laminate may be a laminate 10 (single-sided metal-clad laminate) in which a metal layer 3 is laminated on one side of a polyimide film 1, optionally via an adhesive layer 2, as shown in FIG. 1, or a laminate 20 (double-sided metal-clad laminate) in which a metal layer 3 is laminated on both sides of a polyimide film 1, optionally via an adhesive layer 2, as shown in FIG. 2.

[0148] The material of the adhesive layer is not particularly limited and can be appropriately selected depending on the purpose, and may be, for example, either a thermosetting resin or a thermoplastic resin. From the viewpoint of heat resistance of the laminate, it is preferable that the adhesive layer be a thermoplastic polyimide. The glass transition temperature of the thermoplastic polyimide is preferably not more than 300° C., more preferably not more than 280° C., and even more preferably not more than 260° C. When the glass transition temperature is 300° C. or less, sufficient adhesiveness can be exhibited when, for example, hot roll lamination is performed in the step of bonding a metal layer to a layer containing a polyimide resin.

[0149] [Method of manufacturing laminate] The method for producing the laminate is not particularly limited and can be appropriately selected depending on the purpose. Examples include a method including a step of bonding a metal layer to a layer containing a polyimide resin via an adhesive layer; and a method of directly forming a polyimide film on a metal layer. Examples of methods for laminating a polyimide resin-containing layer and a metal layer include a method using a hot roll laminating device having one or more pairs of metal rolls, a method using continuous processing with a double belt press, etc. Among these, it is preferable to use a hot roll laminating device having one or more pairs of metal rolls because the device configuration is simple and it is advantageous in terms of maintenance costs.

[0150] (Circuit board) The circuit board of the present disclosure includes the laminate of the present disclosure, and may further include other components as necessary. If the metal layer in the laminate is etched to form a desired pattern wiring, the laminate can be suitably used as various flexible printed circuit boards for mounting miniaturized and highly dense components. The applications of the present invention are not limited thereto, and the laminate can be used for various applications as long as it includes a metal layer.

[0151] (antenna) The antenna of the present disclosure includes the circuit board of the present disclosure, and may further include other components as necessary. The antenna is preferably a millimeter wave antenna. "Millimeter wave" refers to frequencies between 30 GHz and 300 GHz (radio wave wavelengths between 1 mm and 10 mm). The polyimide resin of the present disclosure can achieve both a low dielectric constant and a low coefficient of linear expansion, and therefore can be suitably used as a high-frequency band communication antenna that enables ultra-high-speed and large-capacity communication. [Example]

[0152] The present invention will be described in more detail below based on examples, but the present invention is not limited to the following examples.

[0153] <Molecular dynamics simulation of polyimide> Molecular dynamics simulations were performed on homopolymers with specific structural units to calculate the free volume fraction and the average number of adjacent atoms in the amorphous state. Specifically, in steps S1 to S3 below, an appropriate computing device (including input devices, output devices, CPU, memory, etc.) was used to obtain the equilibrium structure using the polymer property automatic calculation system RadonPy (open source software), and the free volume fraction was calculated from the equilibrium structure. In addition, a proprietary Python program was used to calculate the average number of adjacent atoms from the equilibrium structure using a Voronoi diagram.

[0154] The polyimides used in the calculations included a total of approximately 250 types of polyimides, including structures described in PolyInfo (https: / / polymer.nims.go.jp / ) and PI1M (Reference 3: Ruimin Ma and Tengfei Luo, J. Chem. Inf. Model., 60, 10 (2020)), and molecular dynamics simulations were performed on each polyimide.

[0155] Step S1 Amorphous data was obtained for polyimide, a homopolymer with specific structural units. A system was constructed in which 10 polyimide molecules, each with approximately 1000 atoms (specifically, between 900 and 1100 atoms), were arranged. The system in which the polyimide was in an aggregated state was cooled from 800 K to 300 K under a pressure of 1 atm. The cooling rate was 150 ps / K. This allowed data on the initial structure of the amorphous system to be obtained. In this calculation, the force field developed in Reference 4 below was used, and non-bonded and bonded interaction parameters were specified. Reference 4: J. Trag and D. Zahn, Improved GAFF2 Parameters for Fluorinated Alkanes and Mixed Hydro- and Fluorocarbons, J. Mol. Model. 25, 39 (2019).

[0156] Step S2 Next, we performed molecular dynamics simulations to calculate the motion of each atom under conditions of a temperature of 300 K and a pressure of 1 atm. We obtained the coordinates of each atom in the equilibrium system after 500 ns.

[0157] <Calculation of free volume fraction by molecular dynamics simulation> Step S3-1 Next, the free volume fraction f was calculated using the polymer property automatic calculation system RadonPy based on the coordinates of each atom at the final time. The free volume fraction was derived using the following formula 3, and the van der Waals radius of each atom in the formula 3 was calculated based on the GAFF2 force field (see Reference 1 above).

[0158] (Formula 3)

number

[0159] <Calculation of the average number of neighboring atoms using molecular dynamics simulation> Step S3-2 Next, based on the coordinates of each atom at the final time, the average number of neighboring atoms in the system was calculated using the following method. The number of adjacent atoms was calculated as the total number of atom pairs that satisfy the following (a) and (b): (a) In a Voronoi diagram calculated with each atom as a kernel point, atom pairs (pairs of kernel points) that share a Voronoi edge (b) Atom pairs separated by four or more bonds, or atom pairs between different molecules Next, the average number of adjacent atoms was calculated by dividing the total number of pairs (i.e., the number of adjacent atoms) that satisfy both (a) and (b) above in a system with periodic boundary conditions by the number of atoms that make up the system.

[0160] <Calculation of dielectric constant at a frequency of 10 GHz using molecular dynamics simulation> The time series data of the dipole moment of the polyimide was calculated by the following procedure, and the dielectric constant at a frequency of 10 GHz was calculated based on the time series data at frequencies of 10 GHz or higher.

[0161] Specifically, the dipole moment of the target substance was calculated using molecular dynamics calculations, with the length of the dielectric relaxation function set to 100 ns and the time length for calculating the dipole moment set to 500 ns, thereby generating time-series data of the dipole moment. Next, a high-pass filter was designed based on the received calculation conditions. The cutoff frequency of the high-pass filter was set to the inverse of the length of the dielectric relaxation function, and since the length of the dielectric relaxation function was set to 100 ns, the cutoff frequency was set to 10 MHz. Next, the designed high-pass filter was used to remove low-frequency components from the dipole moment time series data. In other words, the frequency band above a cutoff frequency of 10 MHz was extracted from the dipole moment time series data. This generated filtered dipole moment time series data with components below 10 MHz removed.

[0162] Next, the time series data of the filtered dipole moment was taken as M(t), and the dielectric relaxation function Φ(t) was calculated using equation (1). The calculated dielectric relaxation function Φ(t) was fitted using equation (2). Furthermore, the Fourier transform of equation (3) was used to obtain the fitted dielectric relaxation function Φ fit (t) was subjected to frequency decomposition, which gave the frequency-dependent complex permittivity, and the permittivity at a frequency of 10 GHz was calculated from the real part of the complex permittivity at a frequency of 10 GHz.

[0163]

number

[0164]

number

[0165]

number

[0166] <Calculation of linear expansion coefficient by molecular dynamics simulation> First, based on the fluctuations of volume V and enthalpy H in the equilibrium calculation, the volume expansion rate α is calculated using the following formula: P k was calculated. B is the Boltzmann constant, and T is the temperature.

[0167]

number

[0168] Next, assuming the system is isotropic, the linear expansion coefficient α L was derived.

[0169]

number

[0170] Figure 3 is a graph plotting the free volume fraction and the average number of adjacent atoms. In Figure 3, black dots indicate that the linear expansion coefficient and dielectric constant calculated by molecular dynamics simulation are 60 ppm / K or less and 2.5 or less, respectively.

[0171] Figure 4 is a graph plotting the measured values ​​of the dielectric constant and the linear expansion coefficient of various polymers. The measured values ​​were referenced to the values ​​listed in PolyInfo. Figure 4 suggests that there is generally a negative correlation between the two physical properties (correlation coefficient: -0.74), which indicates that it is difficult to achieve both a low linear expansion coefficient and a low dielectric constant.

[0172] Therefore, we visualized polyimides (black dots) that have both a low linear expansion coefficient and a low dielectric constant in Figure 3, and found that polyimides with a low dielectric constant and a low linear expansion coefficient exist in regions with a high free volume fraction and a low average number of adjacent atoms. Specifically, it was found that when the free volume fraction and the average number of adjacent atoms satisfy the following condition (1) or (2), both a low dielectric constant and a low linear expansion coefficient can be achieved. (1) The free volume fraction is 0.23 to 0.38, and the average number of adjacent atoms is 3.80 to 4.75, or (2) The free volume fraction is 0.24 to 0.38, and the average number of adjacent atoms is 3.94 to 4.95.

[0173] The reason why polyimides with a high free volume fraction of 0.23 or more exhibit the properties of low dielectric constant and low linear expansion coefficient is as follows. Polyimides with a high free volume fraction have a rigid or bulky molecular structure as a characteristic feature. In an amorphous state, polyimides with a rigid molecular structure maintain a rod-like shape of the molecular chain regardless of the arrangement of surrounding molecules, making it difficult for the molecular chain to undergo flexible structural changes and pack densely. This is thought to result in a sparse structure. Polyimides with a bulky molecular structure also have a sparse structure because the bulky moieties act as steric hindrances, inhibiting the free internal rotation of the molecular chain, preventing the molecular chain from undergoing flexible structural changes and packing densely. A sparse structure results in a relatively smaller polarization per volume than a dense structure, resulting in a reduced responsiveness to an electric field and contributing to a reduced dielectric constant. Therefore, polyimides with a high free volume fraction, characterized by a rigid or bulky molecular structure, are thought to have a low dielectric constant. Furthermore, in polyimides with a rigid or bulky structure, it is assumed that internal rotation of the molecular chain is inhibited for the above-mentioned reasons, and therefore the change in molecular mobility (change in conformational rotation frequency) caused by thermal energy is thought to be small. A small change in molecular mobility caused by thermal energy means a small change in free volume with respect to a change in temperature, which in turn means that the thermal expansion coefficient is small and the material has a low linear expansion coefficient. Therefore, polyimides with a high free volume fraction, characterized by a rigid or bulky molecular structure, are thought to have a low linear expansion coefficient. For the above reasons, a high free volume fraction of 0.23 or more contributes to a low dielectric constant and a low coefficient of linear expansion.

[0174] Polyimides with a low average number of adjacent atoms (4.95 or less) are polyimides with a high content of sp3 hybridized carbon atoms, such as polyimides containing aliphatic or alicyclic structures. Because sp3 hybridized carbon atoms are surrounded by bonding atoms, they are less likely to contact non-bonded atoms. The average number of adjacent atoms represents the average number of non-bonded atoms surrounding each atom, so the higher the content of sp3 hybridized carbon atoms, the lower the average number of adjacent atoms. In contrast, aromatic polyimides containing a large number of sp2 hybridized carbon atoms tend to exhibit a relatively high dielectric constant because the contribution of π electrons, which have a high polarizability, is included in the dielectric constant. Therefore, as the ratio of sp3 hybridized carbon atoms to sp2 hybridized carbon atoms increases, the contribution of π electrons becomes relatively smaller, resulting in a lower dielectric constant. Therefore, a low average number of neighboring atoms, 4.95 or less, contributes to a low dielectric constant.

[0175] From the above, it was found that a high free volume fraction contributes to a low dielectric constant and a low linear expansion coefficient, and a low average number of adjacent atoms contributes to a low dielectric constant. Therefore, a polyimide with a high free volume fraction and a low average number of adjacent atoms that satisfies the above condition (1) or (2) achieves both a low dielectric constant and a low linear expansion coefficient.

[0176] <Comparison between experimental values ​​and calculated values ​​from molecular dynamics simulation> The experimental values ​​of each polyimide, which are known for its properties of dielectric constant at a frequency of 10 GHz and linear expansion coefficient, were compared with the calculated values ​​obtained by molecular dynamics simulation. The results are shown in Figures 5 and 6. As polyimides for which experimental values ​​are known, specifically, polymers described in PolyInfo and Reference 5 below were used. Reference 5: JO Simpson and AK St.Clair, Thin Solid Films, 308-309 (1997)

[0177] FIG. 5 is a graph showing the relationship between the experimental values ​​and the calculated values ​​of molecular dynamics simulation for the dielectric constant at a frequency of 10 GHz, and FIG. 6 is a graph showing the relationship between the experimental values ​​and the calculated values ​​of molecular dynamics simulation for the linear expansion coefficient. In Figures 5 and 6, each dot represents a polymer for which experimental values ​​obtained through molecular dynamics simulation are known, with the horizontal axis representing the experimental value and the vertical axis representing the calculated value. The correlation coefficients were 0.94 (Figure 5) and 0.91 (Figure 6), respectively, indicating a positive correlation.

[0178] 5 and 6, it was found that the physical property values ​​of the dielectric constant and the linear expansion coefficient obtained by the molecular dynamics simulation qualitatively represent the experimental values. From the above, the two parameters that can achieve both a low dielectric constant and a low linear expansion coefficient (calculated value): the free volume fraction and the average number of adjacent atoms, are effective parameters for designing materials whose target properties are the dielectric constant and the linear expansion coefficient.

[0179] (Synthesis Example 1) Under a nitrogen atmosphere, 3.5 g of 2,3,5,6-tetramethyl-1,4-phenylenediamine (TMPD), 4.8 g of 1,2,4,5-cyclohexanetetracarboxylic dianhydride (HPMDA), and N-methyl-2-pyrrolidone (NMP) were added to a flask and stirred at 25°C for 96 hours to synthesize polyamic acid. The resulting polyamic acid A had an Mw of 7,000. [ka]

[0180] (Synthesis Example 2) Under a nitrogen atmosphere, 1.0 g of 2,4,6-trimethylbenzene-1,3-diamine, 5.9 mL of γ-butyrolactone, 1.5 g of N-ethylpiperidine, and 1.49 g of hexahydro-1H,3H-benzo[1,2-c:4,5-c']difuran-1,3,5,7-tetraone were added to a recovery flask and stirred at 160°C to 215°C for 4 hours. The mixture was then allowed to cool and purified by recrystallization with acetone to yield 1.9 g of powder. IR analysis of the resulting powder confirmed peaks corresponding to C=O and C=N, which are characteristic of imide groups. Therefore, it was confirmed that the corresponding polyimide was obtained according to the following reaction scheme: [ka]

[0181] <Evaluation> The linear expansion coefficient at 20° C. to 200° C. and the relative dielectric constant of the polyimide obtained in Synthesis Example 2 were evaluated by the following procedures.

[0182] <<Coefficient of linear expansion>> First, a sheet with an average thickness of 25 μm was formed using the obtained polyimide as a sample, and the linear expansion coefficient of the polyimide at 20°C to 200°C was measured and evaluated using a thermomechanical analyzer (EXSTAR6000TMA / SS6000, manufactured by SII NanoTechnology Inc.) under the following measurement conditions.

[0183] --Measurement conditions-- First stage: The temperature is increased to 150°C at a rate of 5°C / min to remove adsorbed water from the sample. Second stage: Air-cool to room temperature at a rate of 5°C / min. Third step: The actual measurement is carried out at a temperature increase rate of 5°C / min. The average value of the linear expansion coefficients in the temperature range of 20°C to 200°C in this measurement was determined and used as the linear expansion coefficient of the target polyimide. The "linear expansion coefficient of polyimide at 20°C to 200°C" was evaluated based on the following evaluation criteria.

[0184] -Evaluation criteria- ◯: The linear expansion coefficient of the polyimide is 50 ppm / °C or less. ×: The linear expansion coefficient of the polyimide exceeds 50 ppm / °C.

[0185] <<Dielectric constant>> The obtained polyimide was used to form a sheet having an average thickness of 25 μm as a sample. The dielectric constant of the polyimide was measured by the SPDR method (resonator method) at 25°C and 10 GHz using a vector network analyzer (E5063A, manufactured by Keysight Corporation), and the polyimide was evaluated based on the following evaluation criteria.

[0186] -Evaluation criteria- ◯: The relative dielectric constant of the polyimide is 2.6 or less. ×: The relative dielectric constant of the polyimide is more than 2.6.

[0187] As a result of evaluation of the polyimide obtained in Synthesis Example 2, it was confirmed that the linear expansion coefficient at 20°C to 200°C was evaluated as "good" and the relative dielectric constant of the polyimide was evaluated as "good".

[0188] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims. [Explanation of symbols]

[0189] 1 Polyimide film 2 Adhesive layer 3 metal layer 10 Laminate 20 laminate

Claims

1. consisting of an acid anhydride and a diamine, The acid anhydride is at least one compound selected from the group consisting of compounds represented by the following general formula (A-1): The polyimide resin for high-frequency substrate materials, wherein the diamine is at least one selected from the group consisting of compounds represented by the following general formula (B-1) and compounds represented by the following general formula (B-2): 【Chemistry 1】 In the general formula (A-1), R １ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; l represents an integer of 0 to 3, and when l is 0, it represents that there is no bond; m represents an integer of 0 to 3, n represents an integer of 0 to 5, When n is 0, at least one R １ has a fluorine atom, R ２ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R ２ may be bonded to each other to form a cycloalkyl group, At least one R ２ represents a fluoroalkyl group which may have a substituent, Each X is independently —O—, —C(R ３ ) ２ - and -SO ２ - selected from the group consisting of R ３ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R ３ may be bonded to each other to form a cycloalkyl group. 【Chemistry 2】 In the general formula (B-1), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; l represents an integer of 1 to 3, m represents an integer of 0 to 3, n represents an integer of 0 to 5, o represents an integer from 0 to the maximum number of substituents; R ２ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R ２ may be bonded to each other to form a cycloalkyl group, At least one R ２ represents a fluoroalkyl group which may have a substituent, Each X is independently —O—, —C(R ３ ) ２ - and -SO ２ - selected from the group consisting of R ３ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R ３ may be bonded to each other to form a cycloalkyl group. 【Transformation 3】 In the general formula (B-2), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; At least one R １ has a fluorine atom, m's each independently represent an integer of 0 to 2, o represents an integer from 0 to the maximum number of substituents.

2. 2. The polyimide resin according to claim 1, wherein the general formula (A-1) is either the following general formula (A-1a) or the following general formula (A-1b): 【Chemistry 4】 In the general formula (A-1a), R １ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; At least one R １ has a fluorine atom, m represents an integer of 0 to 3; 【Transformation 5】 In the general formula (A-1b), R １ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; n represents an integer of 1 to 5, R ２ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R ２ may be bonded to each other to form a cycloalkyl group, At least one R ２ represents a fluoroalkyl group which may have a substituent, Each X is independently —O—, —C(R ３ ) ２ - and -SO ２ - selected from the group consisting of R ３ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R ３ may be bonded to each other to form a cycloalkyl group.

3. The general formula (B-1) is either of the following general formula (B-1a) and the following general formula (B-1b), The polyimide resin according to claim 1 or 2, wherein the general formula (B-2) is the following general formula (B-2a): 【Transformation 6】 In the general formula (B-1a), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; o represents an integer of 0 to 4; 【Transformation 7】 In the general formula (B-1b), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; m represents an integer of 1 to 3, o represents an integer from 0 to the maximum number of substituents. 【Transformation 8】 In the general formula (B-2a), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; At least one R １ has a fluorine atom, o represents an integer of 0 to 8.

4. consisting of an acid anhydride and a diamine, the acid anhydride is at least one selected from the group consisting of compounds represented by the following general formulas (A-2a) to (A-2g), The polyimide resin for high-frequency substrate materials, wherein the diamine is at least one selected from the group consisting of compounds represented by the following general formula (B-3) and compounds represented by the following general formula (B-4): 【Chemistry 9】 In the general formulas (A-2a) to (A-2g), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; l represents an integer of 1 to 3, R ２ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. 【Chemistry 10】 In the general formula (B-3), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; l represents an integer of 1 to 3, m represents an integer of 0 to 3, n represents an integer of 0 to 5, o represents an integer from 0 to the maximum number of substituents; R ２ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; At least one R ２ represents a fluoroalkyl group which may have a substituent, Each X is independently —O—, —C(R ３ ) ２ - and -SO ２ - selected from the group consisting of R ３ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R ３ may be bonded to each other to form a cycloalkyl group. 【Chemistry 11】 In the general formula (B-4), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; m's each independently represent an integer of 0 to 2, o represents an integer from 0 to the maximum number of substituents.

5. The general formula (B-3) is either of the following general formula (B-3a) and the following general formula (B-3b), The polyimide resin according to claim 4, wherein the general formula (B-4) is the following general formula (B-4a): 【Chemistry 12】 In the general formula (B-3a), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; o represents an integer of 0 to 4; 【Chemistry 13】 In the general formula (B-3b), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; m represents an integer of 1 to 3, o represents an integer from 0 to the maximum number of substituents. 【Chemistry 14】 In the general formula (B-4a), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; At least one R １ has a fluorine atom, o represents an integer of 0 to 8.

6. The dielectric constant at 10 GHz is 2.6 or less, 5. The polyimide resin according to claim 1, wherein the linear expansion coefficient is 50 ppm / K or less.

7. A polyimide resin having a structural unit represented by the following general formula (1): 【Chemistry 15】 In the general formula (1), R ａ (CO) ４ The R moiety represents a tetravalent group derived from a tetravalent tetracarboxylic acid having two or more carbon atoms. ｂ (N) ２ The moiety represents a tetravalent group derived from a divalent diamine having two or more carbon atoms, The free volume fraction and the average number of adjacent atoms of the polyimide resin in an amorphous state, calculated by molecular dynamics calculation, in an equilibrium state at a temperature of 300 K and a pressure of 1 atm satisfy the following condition (1) or (2): (1) The free volume fraction is 0.23 to 0.38, and the average number of adjacent atoms is 3.80 to 4.75, or (2) The free volume fraction is 0.24 to 0.38, and the average number of adjacent atoms is 3.94 to 4.

95. the average number of adjacent atoms is an average of the number of adjacent atoms per number of atoms constituting the system of the molecular dynamics calculation, The polyimide resin for use as a high-frequency substrate material is such that the number of adjacent atoms is the total number of atom pairs that satisfies the following conditions (a) and (b): (a) Atomic pairs that share one edge of a Voronoi cell with each atom as a kernel point (b) Atomic pairs separated by four or more bonds, or atom pairs between different molecules

8. 8. The polyimide resin according to claim 7, wherein the free volume fraction is 0.23 to 0.32 and the average number of adjacent atoms is 3.90 to 4.

60.

9. the free volume fraction is 0.23 to 0.32, and the average number of adjacent atoms is 3.90 to 4.60; The polyimide resin according to claim 7, which does not have a trifluoromethyl group.

10. the free volume fraction is 0.24 to 0.32, and the average number of adjacent atoms is 3.90 to 4.50; The polyimide resin according to claim 7, which does not have a trifluoromethyl group.

11. the free volume fraction is 0.28 to 0.32, and the average number of adjacent atoms is 3.90 to 4.50; The polyimide resin according to claim 7, which does not have a trifluoromethyl group.

12. The free volume fraction and the average number of adjacent atoms of the polyimide resin in an amorphous state, calculated by molecular dynamics calculation, in an equilibrium state at a temperature of 300 K and a pressure of 1 atm satisfy the following condition (1) or (2): (1) The free volume fraction is 0.23 to 0.38, and the average number of adjacent atoms is 3.80 to 4.75, or (2) The free volume fraction is 0.24 to 0.38, and the average number of adjacent atoms is 3.94 to 4.

95. the average number of adjacent atoms is an average number of adjacent atoms per molecule of the polyimide resin, the average number of adjacent atoms is an average of the number of adjacent atoms per number of atoms constituting the system of the molecular dynamics calculation, 8. The polyimide resin according to claim 1, wherein the number of adjacent atoms is the total number of atom pairs that satisfy the following conditions (a) and (b): (a) Atomic pairs that share one edge of a Voronoi cell with each atom as a kernel point (b) Atomic pairs separated by four or more bonds, or atom pairs between different molecules

13. A composition for use as a high-frequency substrate material, comprising the polyimide resin according to any one of claims 1, 4 and 7.

14. A polyimide film for use as a high-frequency substrate material, comprising the polyimide resin according to any one of claims 1, 4 and 7.

15. a metal layer; A laminate comprising: a layer containing the polyimide resin according to claim 1 , 4 , or 7 .

16. A circuit board comprising the laminate according to claim 15.

17. An antenna comprising the circuit board of claim 16.

18. 18. The antenna of claim 17, which is a millimeter wave antenna.

19. consisting of an acid anhydride and a diamine, The acid anhydride is at least one compound selected from the group consisting of compounds represented by the following general formula (A-1): The polyamic acid for use as a high-frequency substrate material is such that the diamine is at least one selected from the group consisting of compounds represented by the following general formula (B-1) and compounds represented by the following general formula (B-2): 【Chemistry 16】 In the general formula (A-1), R １ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; l represents an integer of 0 to 3, and when l is 0, it represents that there is no bond; m represents an integer of 0 to 3, n represents an integer of 0 to 5, When n is 0, at least one R １ has a fluorine atom, R ２ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R ２ may be bonded to each other to form a cycloalkyl group, At least one R ２ represents a fluoroalkyl group which may have a substituent, Each X is independently —O—, —C(R ３ ) ２ - and -SO ２ - selected from the group consisting of R ３ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R ３ may be bonded to each other to form a cycloalkyl group. 【Chemistry 17】 In the general formula (B-1), R １ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; l represents an integer of 1 to 3, m represents an integer of 0 to 3, n represents an integer of 0 to 5, o represents an integer from 0 to the maximum number of substituents; R ２ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R ２ may be bonded to each other to form a cycloalkyl group, At least one R ２ represents a fluoroalkyl group which may have a substituent, Each X is independently —O—, —C(R ３ ) ２ - and -SO ２ - selected from the group consisting of R ３ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R ３ may be bonded to each other to form a cycloalkyl group. [Chemistry 18] In the general formula (B-2), R １ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; At least one R １ has a fluorine atom, m's each independently represent an integer of 0 to 2, o represents an integer from 0 to the maximum number of substituents.

20. consisting of an acid anhydride and a diamine, the acid anhydride is at least one selected from the group consisting of compounds represented by the following general formulas (A-2a) to (A-2g), The polyamic acid for use as a high-frequency substrate material, wherein the diamine is at least one selected from the group consisting of compounds represented by the following general formula (B-3) and compounds represented by the following general formula (B-4): 【Chemistry 19】 In the general formulas (A-2a) to (A-2g), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; l represents an integer of 1 to 3, R ２ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent. 【Chemistry 20】 In the general formula (B-3), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; l represents an integer of 1 to 3, m represents an integer of 0 to 3, n represents an integer of 0 to 5, o represents an integer from 0 to the maximum number of substituents; R ２ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent; At least one R ２ represents a fluoroalkyl group which may have a substituent, Each X is independently —O—, —C(R ３ ) ２ - and -SO ２ - selected from the group consisting of R ３ are each independently selected from the group consisting of hydrogen, halogen, an alkyl group which may have a substituent, an aromatic ring which may have a substituent, and a heterocycle which may have a substituent, and two adjacent R ３ may be bonded to each other to form a cycloalkyl group. 【Chemistry 21】 In the general formula (B-4), R １ are each independently selected from the group consisting of hydrogen, halogen, an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aromatic ring, and an optionally substituted heterocycle; m's each independently represent an integer of 0 to 2, o represents an integer from 0 to the maximum number of substituents.

21. A composition for use as a high-frequency substrate material, comprising the polyamic acid according to claim 19 or 20 and a solvent.

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