Polyimide film, resin film, metal-clad laminate plate, circuit board, electronic device, and electronic apparatus

Abstract

To provide a polyimide film having low CTE and heat resistance, and further capable of having both low dielectric characteristic and high bending characteristic.SOLUTION: A polyimide film includes: a phenylene group which may have a substituent, or a bivalent group having a biphenyl skeleton which may have a substituent or a naphthalene skeleton; 20 mol% or more and 80 mol% or less of a residue having two ester structure; and 20 mol% or more and 80 mol% or less of a diamine residue derived from a diamine having a phenylene skeleton which may have a substituent, a biphenyl skeleton and the like to a total diamine residues contained in the film, where the inclination of a plastic deformation region in a stress-strain curve is 50 MPa or more and less than 500 MPa.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polyimide film, a resin film, and a metal-clad laminate that are useful, for example, as a circuit board material and have heat resistance, low dielectric properties, and low moisture absorption properties, as well as to a circuit board, an electronic device, and an electronic equipment that utilize them. [Background technology]

[0002] As communication speeds and capacity increase, it is necessary to reduce transmission loss in circuit boards such as printed wiring boards, and their insulating layers are required to have low dielectric constants. A low dielectric loss tangent is necessary to achieve this, and one method of achieving a low dielectric loss tangent is to suppress the mobility of the dielectric material used in the insulating layer. Polyimide is one of the resins commonly used as a dielectric. Polyimide is chemically and thermally stable, and has particularly excellent insulating properties, making it widely used as an insulating resin for circuit board materials.

[0003] While forming a crystalline or ordered structure is effective in suppressing the mobility of polyimides, the high rigidity of these structures leads to problems such as reduced flexibility and toughness. On the other hand, introducing a flexible backbone into polyimides increases the degree of structural freedom, inhibiting the formation of an ordered structure and resulting in a deterioration in the dielectric loss tangent.

[0004] As a conventional technique for reducing the dielectric constant of polyimides, for example, Patent Document 1 proposes a polyimide having a rigid skeleton. The polyimide film of Patent Document 1 has a low coefficient of thermal expansion (CTE) and a low dielectric dissipation factor, but there are concerns about reduced toughness due to its high rigidity. Furthermore, Patent Document 2 proposes a composition containing a thermoplastic polyimide and a polystyrene elastomer (thermoplastic). However, films formed from the composition of Patent Document 2 tend to have a low dielectric dissipation factor but a high CTE. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-6387 [Patent Document 2] Japanese Patent Application Publication No. 2022-99778 Summary of the Invention [Problem to be solved by the invention]

[0006] Conventional techniques have not provided a polyimide film that can stably exhibit low CTE and heat resistance while also achieving low dielectric properties and high flexural properties. Therefore, an object of the present invention is to provide a polyimide film that has a low CTE and heat resistance, and further, can achieve both low dielectric properties and high flexural properties. [Means for solving the problem]

[0007] The polyimide film of the present invention is a polyimide film containing a polyimide containing tetracarboxylic dianhydride residues derived from a tetracarboxylic dianhydride component and diamine residues derived from a diamine component. The polyimide film of the present invention contains tetracarboxylic dianhydride residues derived from a tetracarboxylic dianhydride represented by the following general formula (1) in an amount of 20 mol % to 80 mol % based on the total tetracarboxylic dianhydride residues contained in the film:

[0008] [ka]

[0009] In general formula (1), the group Ar represents a divalent group selected from the following formulae: wherein R1 independently represents an alkyl group having 1 to 3 carbon atoms, m1 independently represents an integer of 0 to 4, and n1 represents an integer of 0 or 1.

[0010] [ka]

[0011] The polyimide film of the present invention contains diamine residues derived from diamines represented by the following general formula (2) in an amount of 20 mol % to 80 mol % based on the total diamine residues contained in the film:

[0012] [ka]

[0013] In general formula (2), the linking group X represents a single bond; R2 independently represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 3 carbon atoms, or an alkoxy group; m2 independently represents an integer of 0 to 4; and n2 independently represents an integer of 0 to 2.

[0014] Furthermore, the polyimide film of the present invention has a gradient of the plastic deformation region in the stress-strain curve within the range of 50 MPa or more and less than 500 MPa.

[0015] The polyimide film of the present invention has a storage modulus of 1×10 at 260°C in a storage modulus-temperature curve obtained by dynamic viscoelasticity measurement of the polyimide film. 7 Pa or more 1×10 9 It may be in the range of Pa or less.

[0016] The polyimide film of the present invention may have a peak of the loss tangent derived from the glass transition temperature (Tg1) in the range of 30 to 170° C., or may have a peak of the loss tangent derived from the glass transition temperature (Tg2) in the range of 180 to 400° C., in a loss tangent-temperature curve obtained by measuring the dynamic viscoelasticity of the polyimide film. In this case, the difference between Tg1 and Tg2 may be 10° C. or more.

[0017] The polyimide film of the present invention may have a dielectric loss tangent of 0.003 or less at 10 GHz when measured with a split post dielectric resonator (SPDR) in an environment where the polyimide film has a temperature of 24 to 26°C and a humidity of 45 to 55%.

[0018] The resin film of the present invention is a resin film containing a single layer or a plurality of resin layers, and contains the polyimide film as at least one of the resin layers.

[0019] The metal-clad laminate of the present invention is a metal-clad laminate comprising an insulating resin layer consisting of a single layer or multiple layers and a metal layer laminated on one or both sides of the insulating resin layer, and at least one layer of the insulating resin layer is made of the polyimide film.

[0020] The circuit board of the present invention is a circuit board comprising an insulating resin layer consisting of a single layer or multiple layers and a conductor circuit layer laminated on one or both sides of the insulating resin layer, and at least one layer of the insulating resin layer is made of the polyimide film.

[0021] The electronic device of the present invention includes the circuit board.

[0022] An electronic device according to the present invention includes the circuit board. [Effects of the Invention]

[0023] The polyimide film of the present invention has a highly rigid skeleton and stably exhibits a low CTE and heat resistance, while controlling the gradient of the plastic deformation region to achieve both low dielectric properties and high flexural strength. Therefore, the polyimide film of the present invention is particularly suitable for use as a circuit board material for FPCs and other electronic devices requiring high-speed signal transmission. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a diagram showing a stress-strain curve in a tensile test of a polyimide film. DETAILED DESCRIPTION OF THE INVENTION

[0025] Hereinafter, an embodiment of the present invention will be described.

[0026] [Polyimide film] The polyimide film of the present invention contains a polyimide containing a tetracarboxylic dianhydride residue derived from a tetracarboxylic dianhydride component and a diamine residue derived from a diamine component. Here, the tetracarboxylic dianhydride residue refers to a tetravalent group derived from a tetracarboxylic dianhydride, and the diamine residue refers to a divalent group derived from a diamine. The polyimide film of the present invention may contain only one type of polyimide or may contain multiple types of polyimides. The polyimide film of the present invention may also contain a resin component other than polyimide. When a resin component other than polyimide is contained, the polyimide film of the present invention preferably contains more than 50 wt % of polyimide, more preferably 60 wt % to 100 wt %, even more preferably 70 wt % to 100 wt %, and most preferably 80 wt % to 100 wt %, based on the total resin components.

[0027] The polyimide film of the present invention contains tetracarboxylic dianhydride residues derived from a tetracarboxylic dianhydride represented by the following general formula (1) [hereinafter, sometimes referred to as "formula (1) residues)] in an amount of 20 mol % to 80 mol % relative to the total tetracarboxylic dianhydride residues contained in the film:

[0028] [ka]

[0029] In the general formula (1), the group Ar represents a divalent group selected from the following formulae:

[0030] [ka]

[0031] In the above formula, R1 independently represents an alkyl group having 1 to 3 carbon atoms, m1 independently represents an integer of 0 to 4, and n1 represents an integer of 0 or 1.

[0032] The residue of formula (1) contains, as the group Ar, a phenylene group which may have a substituent, or a divalent group having a biphenyl skeleton or a naphthalene skeleton which may have a substituent, and has two ester structures directly bonded to the group Ar, which imparts rigidity to the entire polymer chain and enables a low CTE. In addition, the ester structure in the residue of formula (1) has the effect of imparting order to the entire polymer, making it possible to effectively reduce the dielectric loss tangent by improving the molecular order and suppressing its movement.

[0033] Examples of the residue of formula (1) include naphthalene-2,6-diyl bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylate) (DHNTME), p-biphenyl bis(trimellitic acid monoester dihydrate) (BP-TME), 2,2',3,3',5,5'-hexamethyl[1,1'-biphenyl]-4,4'-diyl bis(1,3-dioxo-1,3-dihydro-2-benzofuran-5-carboxylate) (TMPBP-TME), 1,3-dihydro- Residues derived from tetracarboxylic dianhydrides such as 1,3-dioxo-5,5'-(3,3'-dimethyl[1,1'-biphenyl]-4,4'-diyl) ester, 1,3-dihydro-1,3-dioxo-5,5'-(3,3',5,5'-tetramethyl[1,1'-biphenyl]-4,4'-diyl) ester, and p-phenylenebis(trimellitic acid monoester anhydride) (TMHQ) are preferred, and among these, residues derived from DHNTME and BP-TME are particularly preferred.

[0034] If the content of the formula (1) residues relative to the total tetracarboxylic dianhydride residues contained in the polyimide film is less than 20 mol%, the effect of promoting the formation of an ordered structure is small, and a low dielectric tangent is not achieved. On the other hand, if the content of the formula (1) residues is more than 80 mol%, the rigidity increases and the flexibility of the film cannot be ensured. From this perspective, the lower limit of the content of the formula (1) residues contained in the film is preferably 30 mol% or more, more preferably 40 mol% or more, relative to the total tetracarboxylic dianhydride residues. Furthermore, the upper limit of the content of the formula (1) residues contained in the film is preferably 75 mol% or less, more preferably 70 mol% or less, relative to the total tetracarboxylic dianhydride residues.

[0035] The polyimide film of the present invention contains diamine residues derived from a diamine represented by the following general formula (2) [hereinafter, sometimes referred to as "formula (2) residues"] in an amount of 20 mol % to 80 mol % based on the total diamine residues contained in the film.

[0036] [ka]

[0037] In general formula (2), the linking group X represents a single bond; R2 independently represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 3 carbon atoms, or an alkoxy group; m2 independently represents an integer of 0 to 4; and n2 independently represents an integer of 0 to 2.

[0038] The residue of formula (2) has a rigid structure with an amino group at the para-position of a phenylene group or a biphenyl or terphenyl skeleton that may have a substituent, and therefore has the effect of imparting an ordered structure to the entire polymer, suppressing polymer motion and reducing the dielectric loss tangent. Furthermore, the ability to reduce the moisture content within the molecular chain also enables a low dielectric loss tangent.

[0039] Examples of the residue of formula (2) include residues derived from diamines such as 1,4-phenylenediamine (p-PDA), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-diethyl-4,4'-diaminobiphenyl (m-EB), 2,2'-diethoxy-4,4'-diaminobiphenyl (m-EOB), 2,2'-dipropoxy-4,4'-diaminobiphenyl (m-POB), 2,2'-di-n-propyl-4,4'-diaminobiphenyl (m-NPB), 2,2'-divinyl-4,4'-diaminobiphenyl (VAB), 4,4'-diaminobiphenyl, and 4,4''-diamino-p-terphenyl. Among these, residues derived from p-PDA and m-TB are most preferred because they are effective in lowering the CTE and dielectric loss tangent of polyimide films.

[0040] If the content of the formula (2) residue is less than 20 mol% relative to the total diamine residues contained in the film, the effect of promoting the formation of an ordered structure is small, and a low dielectric tangent is not achieved. On the other hand, if the content of the formula (2) residue in the film is more than 80 mol%, the rigidity increases and the flexibility of the film cannot be ensured. From this perspective, the lower limit of the content of the formula (2) residue in the film is preferably 30 mol% or more, more preferably 40 mol% or more, relative to the total diamine residues. Furthermore, the upper limit of the content of the formula (2) residue in the film is preferably 75 mol% or less, more preferably 70 mol% or less, relative to the total diamine residues.

[0041] The polyimide film of the present invention contains the residues of formula (1) and formula (2) in the amounts within the above ranges, which tends to reduce the toughness and flexibility of the film. However, in the present invention, the slope of the plastic deformation region in the stress-strain curve is controlled within a specific range, so that the film can maintain a relatively high rigidity even after plastic deformation, and fractures and cracks during film production and bending can be suppressed.

[0042] The polyimide film of the present invention may contain the above-mentioned contents of the formula (1) residue and the formula (2) residue in a single polyimide, or may contain them in two or more types of polyimides. When the formula (1) residue and the formula (2) residue are contained in a single polyimide, such a polyimide may be referred to as a "rigid polyimide." From the viewpoint of promoting the formation of an ordered structure in the polyimide film and reducing the dielectric loss tangent, the rigid polyimide preferably contains the formula (1) residue in a range of 40 mol % to 100 mol % relative to the total tetracarboxylic dianhydride residues, and the lower limit of the content of the formula (1) residue is more preferably 50 mol % or more, and most preferably 60 mol % or more. Furthermore, from the viewpoint of imparting an ordered structure to the entire polymer, suppressing polymer motion, and reducing the dielectric loss tangent, the rigid polyimide preferably contains 40 mol % or more and 100 mol % or less of the residue of formula (2) relative to all diamine residues, and the lower limit of the content of the residue of formula (2) is more preferably 50 mol % or more, and most preferably 60 mol % or more. The rigid polyimide may contain, as the tetracarboxylic dianhydride residue other than the residue of formula (1) and the diamine residue other than the residue of formula (2), residues derived from monomers generally used as raw materials in the synthesis of polyimides.

[0043] The rigid polyimide is preferably a non-thermoplastic polyimide. Here, the term "non-thermoplastic polyimide" generally refers to a polyimide that does not soften or exhibit adhesiveness even when heated. In the present invention, the non-thermoplastic polyimide has a storage modulus of 1.0×10 at 30°C as measured using a dynamic mechanical analyzer (DMA). 9 The storage modulus is 1.0×10 Pa or more in the temperature range within the glass transition temperature + 30°C. 8 The term "thermoplastic polyimide" generally refers to a polyimide that can be softened by heating and solidified by cooling repeatedly, and has a clearly identifiable glass transition temperature (Tg). In the present invention, however, the term "thermoplastic polyimide" refers to a polyimide having a storage modulus of 1.0 × 10 Pa or more at 30°C as measured using a dynamic viscoelasticity measuring apparatus (DMA). 9The storage modulus is 1.0×10 Pa or more in the temperature range within the glass transition temperature + 30°C. 8 This refers to polyimides that exhibit a modulus of less than Pa.

[0044] [Slope of plastic deformation region] The polyimide film of the present invention has a stress-strain curve with a slope of the plastic deformation region in the range of 50 MPa to less than 500 MPa, preferably 100 MPa to 400 MPa. By controlling the slope of the plastic deformation region within the above range, the polyimide film can stably exhibit a low CTE and heat resistance, while simultaneously achieving low dielectric properties and high flexural strength. Here, the "plastic deformation region" refers to the strain region from the yield point to the break point in the stress-strain curve of a polyimide film in a tensile test. The "resistance to plastic deformation" characteristic refers to a large increase in stress in the plastic deformation region, or the large stress required for plastic deformation. Another way of saying "resistance to plastic deformation" is that the slope in the plastic deformation region is large. The strain at the yield point in a tensile test of a polyimide film varies depending on the material, but it never exceeds 8%. Furthermore, in the plastic deformation region, the stress-strain curve is nearly linear. Therefore, in this invention, the slope of the stress-strain curve in Figure 1 between the strain "8% (E1)" and the "breaking strain (E2)" is defined as the "slope of the plastic deformation region." The "slope of the plastic deformation region" can be calculated using the following formula (a):

[0045] (Calculation method for the slope of the plastic deformation region) Slope of plastic deformation region = (S2-S1) / (E2-E1) (a) where: S1: Stress at 8% strain S2: Breaking stress E1: 8% strain E2: Breaking strain is.

[0046] The polyimide film of the present invention can control the slope of the plastic deformation region within the above range despite containing the rigid skeletons of the residues of formula (1) and formula (2) at the above-mentioned contents. This is because the polyimide film is created in a state where two or more polyimides with different properties are present, or a state equivalent to the presence of two or more polyimides with different properties. Here, "a state equivalent to the presence of two or more polyimides with different properties" refers to a state in which physical properties are exhibited that are approximately equivalent to a state in which two or more polyimides are present. In other words, "a state equivalent to the presence of two or more polyimides with different properties" includes a state in which two or more polyimides are not actually present in the polyimide film, but which can exhibit physical properties equivalent to those in the case in which two or more polyimides are present.

[0047] The polyimide film of the present invention can be in a state where two or more polyimides with different properties are present or in a state equivalent to the presence of two or more polyimides. Therefore, in a loss tangent-temperature curve obtained by dynamic viscoelasticity measurement, it is preferable that the loss tangent peak derived from the glass transition temperature (Tg1) be in the range of 30 to 170°C, and the loss tangent peak derived from the glass transition temperature (Tg2) be in the range of 180 to 400°C. The polyimide film of the present invention can suppress the orientation anisotropy of the polyimide by the component that exhibits Tg1, thereby improving the flexibility of the film and achieving stress relaxation. Meanwhile, the component that exhibits Tg2 can exhibit high elasticity even at high temperatures, which is effective in suppressing breakage during heat treatment and also contributes to a low CTE.

[0048] Furthermore, the polyimide film of the present invention preferably has a difference between Tg1 and Tg2 (Tg2-Tg1) of 10° C. or more, more preferably 30° C. or more. When the temperature difference between the two glass transition temperatures is 10° C. or more, the flexibility of the film is improved, making it easier to prevent breakage.

[0049] In the polyimide film of the present invention, the "state in which two or more polyimides having different properties are present" is, for example, A polyimide (hereinafter sometimes referred to as "polyimide P1") that has a glass transition temperature (Tg1) in the range of 30 to 170°C when formed into a film by itself, A polyimide (hereinafter sometimes referred to as "polyimide P2") that has a glass transition temperature (Tg2) in the range of 180 to 400°C when formed into a film by itself, can be produced by blending the In addition, "a state equivalent to the presence of two or more polyimides with different properties" means, for example, It can be produced by copolymerizing raw material monomers of polyimide P1 and raw material monomers of polyimide P2 so as to contain a block component corresponding to polyimide P1 and a block component corresponding to polyimide P2.

[0050] [Polyimide P1 or equivalent block component] In the polyimide film of the present invention, when two or more polyimides with different properties are present or are equivalent to each other, polyimide P1 or a block component corresponding thereto contributes to stress relaxation. That is, polyimide P1, which has a glass transition temperature (Tg1), improves flexibility and toughness and relieves stress in the film. The weight-average molecular weight of polyimide P1 or its precursor is preferably, for example, in the range of 10,000 to 300,000. If the weight-average molecular weight of polyimide P1 is less than 10,000, the effect of imparting flexibility and toughness to the polyimide film is reduced, while if it exceeds 300,000, solubility in solvents is reduced, making blending difficult.

[0051] The polyimide P1 having a glass transition temperature (Tg1) or a block component corresponding thereto preferably has a structural unit containing an aliphatic chain or an alicyclic skeleton. In the present invention, the "aliphatic chain" refers to a skeleton derived from a hydrocarbon such as an alkane, alkene, or alkyne having 10 or more carbon atoms, preferably 10 to 54 carbon atoms, and may be linear or branched, and may have a substituent. In the present invention, the "alicyclic skeleton" refers to a skeleton derived from a cyclic hydrocarbon such as a cycloalkane or cycloalkene, and may have a side chain or a substituent. In addition, the polyimide P1 is preferably a thermoplastic polyimide, and more preferably a soluble polyimide having solubility in a solvent.

[0052] The structural units containing an aliphatic chain or an alicyclic skeleton contained in the polyimide film of the present invention will be described using the tetracarboxylic dianhydride and diamine used as raw materials. The structural units containing an aliphatic chain or an alicyclic skeleton may be contained in either the acid dianhydride residue or the diamine residue, or may be contained in both. The inclusion of structural units containing an aliphatic chain or an alicyclic skeleton imparts flexibility and toughness to the film, reduces the dielectric loss tangent, and improves the dielectric properties. The structural units containing an aliphatic chain or an alicyclic skeleton may be contained as a tetracarboxylic dianhydride residue or a diamine residue.

[0053] When a structural unit containing an aliphatic chain or an alicyclic skeleton is contained as an acid dianhydride residue, examples of tetracarboxylic acid dianhydrides that can be used as the starting material include cyclohexane-1,2,4,5-tetracarboxylic acid dianhydride (H-PMDA), 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride (CBDA), dicyclohexyl-3,4,3',4'-tetracarboxylic acid dianhydride (H-BPDA), and norbornane-2-spiro-α-cyclopentanone-α'-spiro-2"-norbornane-5,5",6,6"-tetracarboxylic acid dianhydride (CpODA), and among these, H-PMDA and H-BPDA are particularly preferred.

[0054] Furthermore, when a structural unit containing an aliphatic chain or an alicyclic skeleton is contained as a diamine residue, examples of diamines that can be used as the raw material include dimer acid-type diamines in which the two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups, hexamethylenediamine, dodecanediamine, cyclohexanediamine, polyoxyalkyleneamine, and 4,4-diaminodicyclohexylmethane, and among these, dimer acid-type diamines are particularly preferred.

[0055] The dimer acid diamine is a mixture containing the following component (a) as a main component and optionally containing components (b) and (c), and it is preferable to use a purified product in which the amounts of components (b) and (c) are controlled. (a) Dimer diamine (b) Monoamine compounds obtained by substituting the terminal carboxylic acid group of a monobasic acid compound having 10 to 40 carbon atoms with a primary aminomethyl group or an amino group. (c) Amine compounds obtained by substituting the terminal carboxylic acid group of a polybasic acid compound having a hydrocarbon group having 41 to 80 carbon atoms with a primary aminomethyl group or an amino group (excluding the dimer diamine).

[0056] The dimer diamine of component (a) refers to a diamine in which the two terminal carboxylic acid groups (—COOH) of a dimer acid are replaced with primary aminomethyl groups (—CH—NH) or amino groups (—NH). Dimer acids are known dibasic acids obtained by the intermolecular polymerization of unsaturated fatty acids. Their industrial production process is largely standardized in the industry, and they are obtained by dimerizing unsaturated fatty acids with 11 to 22 carbon atoms using a clay catalyst or the like. Industrially obtained dimer acids are primarily composed of a 36-carbon dibasic acid obtained by dimerizing 18-carbon unsaturated fatty acids such as oleic acid, linoleic acid, and linolenic acid. However, depending on the degree of purification, they may contain arbitrary amounts of monomer acid (18 carbon atoms), trimer acid (54 carbon atoms), and other polymerized fatty acids with 20 to 54 carbon atoms. Although double bonds remain after the dimerization reaction, in the present invention, dimer acids that have been further hydrogenated to reduce the degree of unsaturation are also included in the definition of dimer acids. The dimer diamine of component (a) can be defined as a diamine obtained by substituting the terminal carboxylic acid group of a dibasic acid compound having 18 to 54 carbon atoms, preferably 22 to 44 carbon atoms, with a primary aminomethyl group or an amino group.

[0057] Commercially available dimer acid diamines are available, such as Diamine H20 (manufactured by Okamura Oil Mills, Ltd.), and PRIAMINE 1073 (trade name), PRIAMINE 1074 (trade name), and PRIAMINE 1075 (trade name) manufactured by Croda Japan.

[0058] When all of the structural units containing an aliphatic chain or an alicyclic skeleton are contained in polyimide P1, from the viewpoints of imparting flexibility and toughness to the film, lowering the dielectric tangent, and improving the dielectric properties, the structural units containing an aliphatic chain or an alicyclic skeleton are preferably contained in an amount of from 20 mol % to 100 mol % and more preferably from 30 mol % to 80 mol % of the total amount of residues contained in polyimide P1 (total of tetracarboxylic dianhydride residues and diamine residues). Note that polyimide P1 may contain, as the tetracarboxylic dianhydride residues and diamine residues other than those mentioned above, residues derived from monomers generally used as raw materials in the synthesis of polyimides.

[0059] The block component corresponding to polyimide P1 can be synthesized from the raw materials described above for polyimide P1. In addition, tetracarboxylic dianhydrides and diamines commonly used in polyimide synthesis can also be used as raw materials for the block component corresponding to polyimide P1.

[0060] The polyimide film of the present invention effectively contains structural units containing an aliphatic chain or an alicyclic skeleton in an amount of preferably 20 mol% or more, more preferably 25 mol% or more, and particularly preferably 30 mol% or more, based on all structural units of the polyimide contained in the film. Furthermore, the polyimide film of the present invention preferably contains structural units containing an aliphatic chain or an alicyclic skeleton in an amount of 80 mol% or less, more preferably 70 mol% or less, and particularly preferably 60 mol% or less, based on all structural units of the polyimide contained in the film. By including structural units containing an aliphatic chain or an alicyclic skeleton in this range, the polyimide film of the present invention is endowed with flexibility and toughness, and the slope of the plastic deformation region can be controlled to achieve both low dielectric properties and high flexural properties. Furthermore, by setting an upper limit on the content, room is created for the inclusion of residues of formula (1) and formula (2) to improve heat resistance and dielectric properties. If the content of structural units containing an aliphatic chain or an alicyclic skeleton relative to all structural units of the polyimide contained in the film is less than 20 mol %, the dielectric properties and high flexural properties may deteriorate, and if it exceeds 80 mol %, it becomes difficult to impart heat resistance.

[0061] [Polyimide P2 or equivalent block component] In the polyimide film of the present invention, when two or more polyimides with different properties are present or are equivalent to each other, polyimide P2 or a block component corresponding thereto contributes to heat resistance, low CTE, and low dielectric dissipation factor. Specifically, polyimide P2, which has a high glass transition temperature (Tg2), can exhibit high elasticity even at high temperatures, thereby improving heat resistance and effectively suppressing breakage during heat treatment, thereby contributing to a low CTE. Furthermore, the rigid structural units contained in polyimide P2 enable the polyimide film to have a low dielectric dissipation factor. The weight-average molecular weight of polyimide P2 or its precursor is preferably, for example, in the range of 10,000 to 300,000. If the weight-average molecular weight of polyimide P2 is less than 10,000, the effect of imparting properties such as heat resistance, low CTE, and low dielectric dissipation factor to the polyimide film is reduced. If the weight-average molecular weight of polyimide P2 is greater than 300,000, the solubility in solvents is reduced, making blending difficult. A representative example of polyimide P2 is the rigid polyimide having the residues of formula (1) and formula (2).

[0062] The block component corresponding to polyimide P2 can be synthesized from the raw materials described above for the rigid polyimide. In addition to the raw materials described above, the block component corresponding to polyimide P2 can also be synthesized from tetracarboxylic dianhydrides and diamines that are commonly used in polyimide synthesis.

[0063] [Polyimide synthesis] The polyimide contained in the polyimide film of the present invention is preferably produced by any one of the following production methods 1 to 3.

[0064] [Manufacturing method 1] The first embodiment of polyimide synthesis utilizes a polymer blending technique, for example, by mixing a resin solution containing the following component (A) or a precursor thereof with a resin solution containing the following component (B) precursor to obtain a resin composition (V1). (A) Component: Polyimide P1 (B) Component: Polyimide P2

[0065] The method for preparing the resin composition (V1) includes the following steps 1 to 3a: Step 1: (A) preparing a resin solution of component (A) or a precursor thereof; Step 2: (B) preparing a resin solution of a precursor of component; Step 3a: a step of mixing a resin solution of component (A) or a precursor thereof with a resin solution of a precursor of component (B); may include:

[0066] Steps 1 and 2 can be performed by reacting a tetracarboxylic dianhydride and a diamine, which are the raw materials for component (A) or component (B), in a solvent to produce a polyimide precursor (polyamic acid), followed by heating and ring-closure, if necessary. Component (A) can be synthesized from raw materials containing monomers selected from tetracarboxylic dianhydrides and diamines that provide structural units containing an aliphatic chain or alicyclic skeleton. In addition, monomers commonly used in the synthesis of polyimides can also be used. Furthermore, the precursor for component (B) can be synthesized from raw materials containing monomers selected from tetracarboxylic dianhydrides and diamines that provide residues of formula (1) and formula (2). In addition, monomers commonly used in the synthesis of polyimides can also be used.

[0067] In step 3a, the order of adding the resin solution of component (A) or its precursor and the resin solution of component (B) precursor is not important. That is, when preparing resin composition (V1), the resin solution of component (A) or its precursor may be added to the resin solution (varnish) of component (B) precursor and mixed, or the resin solution of component (B) precursor may be added to the resin solution (varnish) of component (A) or its precursor and mixed. The molar ratio (A / B) of component (A) or its precursor to component (B) precursor mixed in step 3a is preferably within the range of 20 / 80 to 80 / 20, and more preferably within the range of 25 / 75 to 70 / 30 from the viewpoint of achieving low dielectric loss tangent and low CTE. If the molar ratio (A / B) is less than 20 / 80, the effect of reducing the dielectric loss tangent of the polyimide film may not be fully realized, while if it exceeds 80 / 20, the effect of imparting heat resistance to the polyimide film may not be fully realized.

[0068] The resin composition (V1) may contain a solvent such as an organic solvent. Since the component (A) or its precursor and the precursor of the component (B) are soluble in solvents and exhibit good solubility, the resin composition (V1) can be prepared as a polyimide solution (varnish) containing a solvent. In the present invention, the term "solvent" includes organic solvents and is used in a broader sense than organic solvents.

[0069] Examples of organic solvents that can be used in steps 1 to 3a include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethyl sulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, γ-butyrolactone, diglyme, triglyme, cresol, methyl ethyl ketone, hexane, methanol, and ethanol. Mixtures of one or more solvents selected from these groups, and aromatic hydrocarbon solvents such as xylene and toluene, are preferably used in any ratio, and more preferably in a ratio of 50 to 100:0 to 50. The solvent content is not particularly limited, but is preferably adjusted so that the total concentration of the resin components is about 5 to 50 wt.% relative to the entire mixture of resin composition (V1).

[0070] [Manufacturing method 2] A second embodiment of polyimide synthesis utilizes a polymer blending technique. In the second embodiment, the following component (A) or a precursor thereof and a precursor of component (B) are used as raw materials to produce a resin composition (V2) containing the reaction product of these components, component (C1). (A) Component: Polyimide P1 (B) Component: Polyimide P2

[0071] The method for preparing the resin composition (V2) includes the following steps 1 to 3b: Step 1: (A) preparing a resin solution of component (A) or a precursor thereof; Step 2: (B) preparing a resin solution of a precursor of component; Step 3b: a step of mixing a resin solution of component (A) or a precursor thereof with a resin solution of a precursor of component (B) to synthesize component (C1) as a reaction product; may include:

[0072] Steps 1 and 2 can be carried out in the same manner as in Production Method 1. In step 3b, the order of adding the resin solution of component (A) or its precursor and the resin solution of component (B) precursor is not important. The molar ratio (A / B) of component (A) or its precursor to component (B) precursor mixed in step 3b is preferably within the range of 20 / 80 to 80 / 20, and more preferably within the range of 25 / 75 to 70 / 30 from the viewpoint of low dielectric loss tangent and low CTE. If the molar ratio (A / B) is less than 20 / 80, the effect of lowering the dielectric loss tangent of the polyimide film may not be fully realized, while if it exceeds 80 / 20, the effect of imparting heat resistance to the polyimide film may not be fully realized.

[0073] The reaction product, component (C1), is a polymer in which polyimide P1 or its precursor and a precursor of polyimide P2 are covalently linked. For example, in step 3b, a resin solution of component (A) or its precursor and a resin solution of a precursor of component (B) are mixed, and an amide bond is formed at the polymer chain end between a portion of component (A) or its precursor and a portion of the precursor of component (B), thereby forming component (C1). The reaction conditions in step 3b are not particularly limited; for example, component (C1) can be synthesized by stirring at room temperature for approximately 10 to 72 hours. In this case, step 3b is preferably performed under an inert gas atmosphere. The formation of a new chemical bond, such as an amide bond, can be confirmed, for example, by nuclear magnetic resonance spectroscopy (NMR).

[0074] In the above steps 1 to 3b, when component (A) or its precursor has an acid terminal, a precursor of component (B) having an amine terminal is used; when component (A) or its precursor has an amine terminal, a precursor of component (B) having an acid terminal is used. In this way, by mixing polymers with different terminal functional groups, the reaction product (C1) can be efficiently synthesized. Note that "acid terminal" refers to a state in which an acid anhydride group or a carboxyl group (-COOH) is present at the end of the polymer chain, and "amine terminal" refers to a state in which an amino group is present at the end of the polymer chain. Whether component (A) or its precursor or the precursor of component (B) is acid-terminated or amine-terminated can be adjusted by adjusting the molar ratio of the raw material tetracarboxylic dianhydride component and diamine component. For example, by setting the molar ratio of the tetracarboxylic dianhydride component to the diamine component (tetracarboxylic dianhydride component / diamine component) to less than 1.0, component (A) or its precursor and the precursor of component (B) can be amine-terminated. On the other hand, by setting the molar ratio of the tetracarboxylic dianhydride component to the diamine component (tetracarboxylic dianhydride component / diamine component) to a range of more than 1.0, it is possible to make the component (A) or its precursor and the precursor of the component (B) acid-terminated.

[0075] The resin composition (V2) obtained by steps 1 to 3b may contain, in addition to the reactant component (C1), component (A) or its precursor and / or a precursor of component (B). The resin composition (V2) may also contain a solvent such as an organic solvent. In producing the resin composition (V2), the same solvents as those described for the resin composition (V1) can be used in steps 1 to 3b.

[0076] The resin compositions (V1) and (V2) obtained by the above-mentioned Production Methods 1 and 2 may contain either polyimide P1 or its precursor, or may contain a precursor of polyimide P2. The polyimide P1 or its precursor or the precursor of polyimide P2 in the resin compositions (V1) and (V2) may have an amide acid structure or may contain an imide structure, but preferably contains at least an imide structure, and may contain both an amide acid structure and an imide structure. Furthermore, the reactant component (C1) may have a molecule having an amide acid skeleton and a molecule having an imide skeleton covalently bonded thereto.

[0077] [Manufacturing method 3] In a third embodiment of polyimide synthesis, copolymerization is carried out so that the resulting polyimide contains a structural unit containing an aliphatic chain or an alicyclic skeleton and a residue of formula (1) and a residue of formula (2). In this case, the copolymerized polyimide may contain structural units other than the structural unit containing an aliphatic chain or an alicyclic skeleton, the residue of formula (1), and the residue of formula (2). Such other structural units may be acid dianhydride residues, diamine residues, or both acid dianhydride residues and diamine residues.

[0078] In a third embodiment, tetracarboxylic dianhydride and diamine, which are raw materials that provide structural units containing at least an aliphatic chain or alicyclic skeleton and residues of formula (1) and formula (2), are reacted in a solvent to produce a precursor polyamic acid, which is then subjected to thermal ring closure (imidization). For example, a precursor polyamic acid solution is obtained by dissolving approximately equimolar amounts of tetracarboxylic dianhydride and diamine in an organic solvent and stirring at a temperature within the range of 0 to 100°C for 30 minutes to 1 week to cause a polymerization reaction. Alternatively, a polyamic acid solution with high solvent solubility, such as one containing a dimer acid-type diamine, is obtained by heating and stirring at approximately 150 to 240°C for 2 to 10 hours. This polyamic acid solution or polyimide solution is designated as resin composition (V3). In either case, the reaction components, tetracarboxylic dianhydride and diamine, can be used alone or in combination of two or more. The order and timing of addition to the reaction vessel are not limited, but it is preferable to add and dissolve at least one diamine component in the solvent before the tetracarboxylic dianhydride. Two or more types of polyamic acid solutions and / or polyimide solutions that have been reacted in separate reaction vessels may be mixed together, or the reaction may be carried out in a single reaction vessel.

[0079] In the polymerization reaction, the reaction components can be dissolved in an organic solvent to a concentration of 5 to 50% by weight, preferably 10 to 35% by weight. The organic solvent used in the polymerization reaction can be, for example, the organic solvent described for resin composition (V1). The amount of organic solvent used is not particularly limited, but it is preferable to adjust the amount used so that the concentration of the polyamic acid and / or polyimide obtained by the polymerization reaction is about 5 to 50% by weight. Resin composition (V3) can also contain a solvent such as the organic solvent described for resin composition (V1). In the copolymerized polyimide, the structural units containing an aliphatic chain or alicyclic skeleton and the structural units containing the residues of formula (1) and formula (2) may exist as blocks or randomly, but are preferably blocked to an extent that the polyimide film can exhibit Tg1 and Tg2.

[0080] [Polyimide film manufacturing method] The polyimide film of the present invention is produced by using resin composition (V1), (V2), or (V3), and optionally imidizing the polyimide precursor in the resin composition and forming it into a film. There are no particular limitations on the method for producing the polyimide film of the present invention, and known techniques can be used. For example, the polyimide film is preferably produced by repeatedly applying resin composition (V1), (V2), or (V3) to a supporting substrate and drying the composition once or multiple times. There are no particular limitations on the method for applying the resin composition to the supporting substrate, and coating can be performed using a coater such as a comma coater, a die coater, a knife coater, or a lip coater. There are no particular limitations on the imidization method, and a suitable method is, for example, heat treatment at a temperature in the range of 80 to 400°C for 1 to 24 hours. The heating temperature may be constant, or the temperature can be changed during the process. In the polyimide film of the present invention, polyimide P1, polyimide P2, etc., are most preferably fully imidized. However, a portion of the polyimide may be an amic acid. The imidization rate was determined by measuring the infrared absorption spectrum of the polyimide thin film by a single-reflection ATR method using a Fourier transform infrared spectrophotometer (commercially available: JASCO Corporation, product name: FT / IR620). -1 Based on the benzene ring absorber near 1780cm -1 It can be calculated from the absorbance of the C=O stretching derived from the imide group. By using a metal foil as the supporting substrate, the metal-clad laminate of the present invention described below can be produced.

[0081] When the polyimide film of the present invention is produced according to Production Method 1, the following components (A) and (B) are required: (A): Polyimide P1, and, (B): Polyimide P2, The resulting polyimide film contains the above as a resin component.

[0082] When the polyimide film of the present invention is produced according to Production Method 2, the following components (A), (B), and (C2) are used: (A): Polyimide P1, (B): Polyimide P2, and, (C2): a polyimide in which polyimide P1 and polyimide P2 are linked by a covalent bond; The polyimide film contains the above as a resin component. The component (C2) is obtained by imidizing the amide acid skeleton in the component (C1), which is the reaction product in the above-mentioned step 3b.

[0083] Component (C2) is a reaction product between component (A) and component (B) (including a product that has reacted at the precursor stage and then been imidized), and is formed by a covalent bond between a reactive functional group of component (A) and a reactive functional group of component (B). For example, the reactive functional groups of components (A) and (B) may be linked via an amide bond. Specifically, component (C2) may have a block structure in which the acid terminal of polyimide P1 of component (A) is linked to the amine terminal of polyimide P2 of component (B), or the amine terminal of polyimide P1 of component (A) is linked to the acid terminal of polyimide P2 of component (B). Such a block structure allows component (C2) to have a low dielectric tangent and a high glass transition temperature when formed into a film. Examples of covalent bonds include single bonds (carbon-carbon), amide bonds, ester bonds, imino bonds, imide bonds, ether bonds, and sulfide bonds. In addition to the examples given here, general covalent bonds may also be included.

[0084] When the polyimide film of the present invention is produced according to Production Method 3, the resulting polyimide film contains a polyimide in which structural units containing an aliphatic chain or an alicyclic skeleton and structural units containing residues of formula (1) and formula (2) are copolymerized in a block or random manner, preferably in a block manner.

[0085] [Optional ingredients] The polyimide film of the present invention may contain optional components such as inorganic fillers, organic fillers, plasticizers, curing accelerators, coupling agents, pigments, and flame retardants, as long as the components do not impair the effects of the invention. Examples of inorganic fillers include silicon dioxide, aluminum oxide, beryllium oxide, niobium oxide, titanium oxide, magnesium oxide, boron nitride, aluminum nitride, silicon nitride, aluminum fluoride, calcium fluoride, magnesium fluoride, potassium silicofluoride, and metal phosphinates. These may be used alone or in combination. Other resin components may also be added as optional components, as long as the components do not impair the effects of the invention.

[0086] Thickness The thickness of the polyimide film of the present invention is not particularly limited and can be appropriately set depending on the intended use, but when used as a circuit board material, it is preferably in the range of 2 to 150 μm, more preferably 5 to 75 μm, and most preferably 15 to 55 μm. If the polyimide film is less than 2 μm thick, problems such as wrinkles may occur during transport during production of the polyimide film, or sufficient toughness may not be exhibited, resulting in a failure to obtain a self-supporting film. On the other hand, if the polyimide film thickness exceeds 150 μm, there is a risk of a decrease in productivity of the polyimide film.

[0087] [CTE] The polyimide film of the present invention preferably has a CTE of 50 ppm / K or less, more preferably in the range of 0 to 30 ppm / K. By having a CTE of 50 ppm / K or less, the dimensional change rate can be easily controlled when a resin film or a metal-clad laminate is formed. The CTE can be measured by the method shown in the Examples below.

[0088] [Dielectric properties] The polyimide film of the present invention preferably has a dielectric loss tangent at 10 GHz of 0.003 or less when measured using a split post dielectric resonator (SPDR) at a temperature of 24 to 26°C and a humidity of 45 to 55%. A dielectric loss tangent at 10 GHz of 0.003 or less can suppress transmission loss of high-frequency signals in the GHz band in a typical usage environment expected for, for example, a circuit board. If the dielectric loss tangent at 10 GHz exceeds 0.003, problems such as electrical signal loss are likely to occur in the transmission path of high-frequency signals when used in, for example, a circuit board such as an FPC. From this perspective, the dielectric loss tangent at 10 GHz is preferably 0.0025 or less, more preferably 0.0022 or less, and most preferably 0.0020 or less. The dielectric loss tangent can be measured by the method described in the Examples below.

[0089] [Storage modulus] The polyimide film of the present invention has a storage modulus of 1×10 at 260°C in a storage modulus-temperature curve obtained by dynamic viscoelasticity measurement. 7 Pa or more 1×10 9 It is preferable that the range is 5×10 Pa or less. 7 Pa or more 7×10 8 It is more preferable that the storage modulus at 260°C is in the range of 0.1 Pa or less. When the storage modulus at 260°C is in the above range, the heat resistance of the polyimide film is improved, and it is possible to suppress the occurrence of blisters and the like even under high temperature conditions such as during solder reflow. The storage modulus can be measured by the method described in the Examples below.

[0090] Tensile modulus The polyimide film of the present invention preferably has a tensile modulus of elasticity of 1.0 GPa or more, more preferably in the range of 1.0 GPa to 6.0 GPa. If the tensile modulus is less than 1.0 GPa, tack occurs, making it difficult to form a film that is easy to process. The tensile modulus can be measured by the method shown in the Examples below.

[0091] [Elongation] The polyimide film of the present invention preferably has an elongation of 5% or more, more preferably in the range of 5% to 50%, and most preferably in the range of 8% to 40%. An elongation of less than 5% leads to a deterioration in toughness. The elongation can be measured by the method shown in the Examples below.

[0092] The polyimide film of the present invention is a single layer, but may be laminated with any layer. That is, it may be in the form of an insulating resin film (sheet) containing the polyimide film of the present invention, or may be laminated directly or via any layer on a supporting substrate such as a metal foil such as copper foil, a glass plate, or a resin sheet. Note that by using a metal foil as the supporting substrate, the metal-clad laminate of the present invention described below can be produced.

[0093] The polyimide film of the present invention has a highly rigid skeleton and stably exhibits a low CTE and heat resistance, while controlling the gradient of the plastic deformation region, thereby achieving both low dielectric properties and high flexural strength. Therefore, the polyimide film of the present invention is useful as a material for insulating layers in circuit boards and the like.

[0094] [Resin film] The resin film of the present invention may include a single layer or multiple resin layers, at least one of which may comprise a layer made of the polyimide film of the present invention. The resin film of the present invention may also include, in addition to the polyimide film of the present invention, a resin layer containing another polyimide or a resin layer containing a resin other than a polyimide.

[0095] [Metal-clad laminate] A metal-clad laminate according to one embodiment of the present invention comprises an insulating resin layer consisting of a single layer or multiple layers and a metal layer laminated on one or both surfaces of the insulating resin layer, at least one of which is made of the polyimide film of the present invention. Circuit boards such as FPCs can be manufactured by processing one or more metal layers of the metal-clad laminate into a pattern using a conventional method to form a wiring layer (conductor circuit layer). The metal-clad laminate of the present invention may also include any other layers.

[0096] The material of the metal layer is not particularly limited, but examples thereof include copper, stainless steel, iron, nickel, beryllium, aluminum, zinc, indium, silver, gold, tin, zirconium, tantalum, titanium, lead, magnesium, manganese, and alloys thereof. Among these, copper or copper alloys are particularly preferred. The material of the wiring layer in the circuit board of this embodiment, which will be described later, is the same as that of the metal layer.

[0097] The thickness of the metal layer is not particularly limited, but when a metal foil such as copper foil is used, it is preferably 35 μm or less, and more preferably in the range of 5 to 25 μm. From the viewpoint of production stability and handling, the lower limit of the thickness of the metal foil is preferably 5 μm. When copper foil is used, it may be rolled copper foil or electrolytic copper foil. Furthermore, commercially available copper foil may be used as the copper foil.

[0098] The surface roughness of the metal layer is not particularly limited, but from the viewpoint of ensuring adhesion to the adhesive layer while reducing conductor loss, it is preferable that the metal layer has a roughened surface with a ten-point average roughness (Rzjis) in the range of 0.3 to 1.5 μm. Furthermore, the metal foil may be subjected to surface treatment with, for example, siding, aluminum alcoholate, aluminum chelate, silane coupling agent, etc., for the purpose of, for example, rust prevention treatment or improving adhesive strength.

[0099] The method for laminating with a metal layer is not particularly limited, and examples thereof include, as described above, a method in which a metal foil is used as a supporting substrate and a polyimide resin composition is applied thereto, a method in which the polyimide film is laminated and pressure-bonded, and a method in which a metal layer is formed on the polyimide film by vapor deposition.

[0100] [Circuit board] A circuit board according to one embodiment of the present invention is formed by wiring the metal layer of the metal-clad laminate. That is, the circuit board of the present invention comprises an insulating resin layer consisting of a single layer or multiple layers and a conductor circuit layer laminated on one or both surfaces of the insulating resin layer, at least one layer of which is made of the polyimide film of the present invention. Note that the circuit board of the present invention may include any layer other than those described above, and may also include a coverlay film that covers the wiring layer.

[0101] [Electronic Devices and Electronic Equipment] The electronic devices and electronic equipment according to the embodiments of the present invention include the above-described circuit board. Examples of the electronic devices according to the present embodiments include display devices such as liquid crystal displays, organic EL displays, and electronic paper, as well as organic EL lighting, solar cells, touch panels, camera modules, inverters, converters, and components thereof. Examples of the electronic equipment include hard disk drives, DVDs, mobile phones, smartphones, tablet devices, automotive electronic control units (ECUs), and power control units (PCUs). Circuit boards are preferably used in these electronic devices and electronic equipment as components such as wiring for moving parts, cables, and connectors. [Example]

[0102] The features of the present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to these examples. In the following examples, various measurements and evaluations are as follows, unless otherwise specified.

[0103] [Measurement of weight average molecular weight (Mw) and number average molecular weight (Mn)] The weight-average molecular weight and number-average molecular weight were measured by gel permeation chromatography (Tosoh Corporation, HLC-8420GPC). Polystyrene was used as a standard substance, and either tetrahydrofuran (THF) or N,N-dimethylacetamide (DMAc) was used as the developing solvent depending on the solubility of the resin.

[0104] [Viscosity measurement] The viscosity was measured at 25°C using an E-type viscometer (Brookfield, product name: DV-II+Pro). The rotation speed was set so that the torque was 10% to 90%, and the viscosity was read when the viscosity stabilized 2 minutes after the start of measurement.

[0105] [Measurement of storage modulus and glass transition temperature (Tg)] The storage modulus was measured using a dynamic viscoelasticity measuring device (DMA: manufactured by TA Instruments, product name: RSA G2) on a 5 mm × 70 mm polyimide film at a temperature increase rate of 4°C / min from 30°C to 500°C at a frequency of 1 Hz, and the storage modulus was determined at 260°C. The maximum peak of the measured Tan δ was defined as the glass transition temperature (Tg).

[0106] [Measurement of coefficient of thermal expansion (CTE)] A 3 mm x 20 mm polyimide film was heated from 30°C to 180°C at a constant heating rate while applying a 5.0 g load using a thermomechanical analyzer (Hitachi High-Technology Corporation (formerly Seiko Instruments Inc.), product name: TMA / SS6100). The film was then held at that temperature for 10 minutes and then cooled at a rate of 5°C / min to determine the average thermal expansion coefficient (thermal expansion coefficient) from 180°C to 100°C.

[0107] [Measurement of relative permittivity (Dk) and dielectric loss tangent (Df)] The dielectric constant (Dk) and dielectric loss tangent (Df) of the polyimide film at a frequency of 10 GHz were measured using a vector network analyzer (Agilent, product name: E8363C) and a split post dielectric resonator (SPDR resonator). Note that the Dk and Df values ​​under humidity control were measured after the polyimide film used for the measurement was left for 24 hours under conditions of temperature: 24-26°C and humidity: 45-55%.

[0108] [Measurement of tensile modulus and elongation] Using a Strograph R-1 (manufactured by Toyo Seiki Seisakusho Co., Ltd.), a tensile test was performed on a polyimide film measuring 25 μm in thickness, 12.7 mm in width, and 127 mm in length at 50 mm / min under an environment of 23°C and 50% relative humidity, and the tensile modulus and elongation of the polyimide film were calculated. In addition, the slope of the plastic deformation region after the inflection point was calculated from the measured stress-strain curve.

[0109] [Measurement of copper foil surface roughness] The surface roughness of the copper foil was measured in tapping mode over an area of ​​80 μm × 80 μm on the copper foil surface using an AFM (manufactured by Bruker AXS, product name: Dimension Icon type SPM) and a probe (manufactured by Bruker AXS, product name: TESPA (NCHV), tip curvature radius 10 nm, spring constant 42 N / m), and the ten-point average roughness (Rzjis) was calculated.

[0110] [Film bending test] The polyimide film was bent 180° and examined for breakage or cracking. If breakage or cracking occurred, the film was rated as × (bad), and if no breakage or cracking occurred and the original shape was maintained, it was rated as ◯ (good).

[0111] The abbreviations used in the examples and comparative examples represent the following compounds. DDA: aliphatic diamine with 36 carbon atoms (PRIAMINE 1075 manufactured by Croda Japan Co., Ltd., molecular weight 536.90 g / mol, amine value: 209 mg KOH / g) Diamine H20: aliphatic amine with 20 carbon atoms (manufactured by Okamura Oil Mills, molecular weight 325.09 g / mol) m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl 6FDA: 4,4'-(hexafluoroisopropylidene)diphthalic anhydride 26DHN-TME: 2,6-naphthalenebis(trimellitic acid monoester acid anhydride) (CAS number: 115383-00-1) BP-TME: 4,4'-biphenylbis(trimellitic acid monoester acid anhydride) (CAS number: 10340-81-5) TMHQ: p-phenylenebis(trimellitic acid monoester acid anhydride) NMP: N-methyl-2-pyrrolidone

[0112] <Synthesis of soluble polyimide solution> (Synthesis Example 1) Under a nitrogen stream, 35.7565 g of 6FDA (0.08034 mol), 44.2431 g of DDA (0.08240 mol), 112.00 g of NMP, and 74.67 g of xylene were added to a 500 mL separable flask and mixed thoroughly at 40 °C for 1 hour to prepare a polyamic acid solution. This polyamic acid solution was heated to 190 °C and stirred for 5 hours. Xylene was added in an amount to achieve a solids concentration of 23.4 wt% after polymerization, completing the imidization to prepare soluble polyimide solution A (solids concentration: 23.4 wt%, weight average molecular weight: 65,879, number average molecular weight: 34,600, viscosity: 762 cP). A polyimide film was produced using soluble polyimide solution A, and the Tg was 39 °C.

[0113] (Synthesis Example 2) Under a nitrogen stream, 17.1696 g of 6FDA (0.03858 mol), 18.8306 g of DDA (0.03507 mol), 50.40 g of NMP, and 33.60 g of xylene were added to a 500 mL separable flask and mixed thoroughly at 40 °C for 1 hour to prepare a polyamic acid solution. This polyamic acid solution was heated to 190 °C and stirred for 5 hours. Xylene was added in an amount to achieve a solids concentration of 29.7 wt% after polymerization, completing the imidization to prepare soluble polyimide solution B (solids concentration: 29.7 wt%, weight average molecular weight: 17,426, number average molecular weight: 12,556, viscosity: 151 cP). A polyimide film was produced using soluble polyimide solution B, and the Tg was 38 °C.

[0114] (Synthesis Example 3) Under a nitrogen stream, 17.1696 g of 6FDA (0.03858 mol), 11.2757 g of Diamine H2O (0.03507 mol), 50.40 g of NMP, and 33.60 g of xylene were added to a 500 mL separable flask and mixed thoroughly at 40 °C for 1 hour to prepare a polyamic acid solution. This polyamic acid solution was heated to 190 °C, heated and stirred for 5 hours, and an amount of xylene was added to complete the imidization so that the solids concentration after polymerization was 29.7 wt%. Soluble polyimide solution C (solids concentration: 29.7 wt%, weight average molecular weight: 26,370, number average molecular weight: 12,606, viscosity: 238 cP) was prepared. A polyimide film was produced using soluble polyimide solution C, and its Tg was 65 °C.

[0115] <Synthesis of non-thermoplastic polyamic acid solution> (Synthesis Example 4) Under a nitrogen stream, 13.8095 g of m-TB (0.06496 mol) and an amount of NMP such that the solids concentration after polymerization was 15 wt% were added to a 500 mL separable flask and dissolved by stirring at room temperature. Next, 31.1905 g of 26DHN-TME (0.06074 mol) was added, and the mixture was polymerized by stirring at room temperature for one week to prepare polyamic acid solution D (solids concentration: 15 wt%, weight average molecular weight: 52,710, number average molecular weight: 24,336, viscosity: 5,080 cP). A polyimide film was produced using polyamic acid solution D, and its Tg was 229 °C.

[0116] (Synthesis Example 5) Under a nitrogen stream, 13.8095 g of m-TB (0.06496 mol) and an amount of NMP such that the solids concentration after polymerization was 20 wt% were added to a 500 mL separable flask and dissolved by stirring at room temperature. Next, 31.1905 g of 26DHN-TME (0.06074 mol) was added, and the mixture was polymerized by stirring at room temperature for one week to prepare polyamic acid solution E (solids concentration: 20 wt%, weight average molecular weight: 56,943, number average molecular weight: 23,864, viscosity: 55,563 cP). A polyimide film was produced using polyamic acid solution E, and its Tg was 229 °C.

[0117] (Synthesis Example 6) Under a nitrogen stream, 13.8095 g of m-TB (0.06496 mol) and an amount of NMP such that the solids concentration after polymerization would be 15 wt% were added to a 500 mL separable flask and stirred at room temperature to dissolve. Next, 32.4613 g of BP-TME (0.06074 mol) was added, and the polymerization reaction was continued with stirring at room temperature for one week to prepare polyamic acid solution F (solids concentration: 15 wt%, weight average molecular weight: 55,193, number average molecular weight: 25,932, viscosity: 8,273 cP). When polyimide film was produced using polyamic acid solution F, the Tg was 250 °C.

[0118] (Synthesis Example 7) Under a nitrogen stream, 13.8095 g of m-TB (0.06496 mol) and an amount of NMP to achieve a solids concentration of 15 wt% after polymerization were added to a 500 mL separable flask and stirred at room temperature to dissolve. Next, 27.8390 g of TMHQ (0.06074 mol) was added, and the mixture was polymerized with stirring at room temperature for one week to prepare polyamic acid solution G (solids concentration: 15 wt%, weight average molecular weight: 78,440, number average molecular weight: 32,338, viscosity: 101,500 cP). A polyimide film was produced using polyamic acid solution G, and its Tg was 252 °C.

[0119] The soluble polyimides synthesized in Synthesis Examples 1 to 3 correspond to polyimide P1, and the non-thermoplastic polyimides synthesized in Synthesis Examples 4 to 7 correspond to polyimide P2.

[0120] [Example 1] <Preparation of Resin Composition 1> 22.47 g of solvent-soluble polyimide solution A was mixed with 35.00 g of non-thermoplastic polyamic acid solution D, and the mixture was diluted with 7.35 g of NMP and 5.17 g of xylene and stirred to prepare resin composition 1 (solid content 15%, viscosity 960 cP).

[0121] <Preparation of Polyimide Film 1> Resin composition 1 was uniformly applied to copper foil 1 (electrolytic copper foil, thickness: 12 μm, resin side roughness Rzjis: 0.6 μm) to a thickness of 25 μm after curing, and then heated and dried at 100 to 120°C for 10 minutes to remove the solvent. Further, heat treatment was performed from room temperature to 320°C at a heating rate of 5°C / min to complete imidization, yielding a single-sided copper-clad laminate. The copper foil of the single-sided copper-clad laminate was then etched away using an aqueous ferric chloride solution to yield polyimide film 1. The various evaluation results of polyimide film 1 are as follows. Dk: 2.9, Df: 0.0022, CTE: 13 ppm / K, Tg1: 28°C, Tg2: 216°C, tensile modulus: 3.1 GPa, elongation: 8.1%, slope of plastic deformation region: 331 MPa, storage modulus at 260°C: 3.00 x 10 8Pa, bending test;

[0122] [Examples 2 to 8] Resin compositions and polyimide films were prepared using the compositions shown in Table 1, and various physical properties were measured in the same manner as in Example 1. The results are shown in Table 2.

[0123] [Table 1]

[0124] [Table 2]

[0125] (Comparative Example 1) A single-sided copper-clad laminate and a polyimide film were prepared and their physical properties were measured in the same manner as in Example 1, except that Soluble Polyimide Solution A was used instead of Resin Composition 1. The results are shown in Table 3.

[0126] (Comparative Example 2) A single-sided copper-clad laminate and a polyimide film were prepared and their physical properties were measured in the same manner as in Example 1, except that polyamic acid solution D was used instead of resin composition 1. The results are shown in Table 3.

[0127] [Table 3]

[0128] As can be seen from Table 2, in Examples 1 to 8, polyimide films were obtained in which the slope of the plastic deformation region in the stress-strain curve was in the range of 50 MPa or more and less than 500 MPa by incorporating structural units containing an aliphatic chain or an alicyclic skeleton in addition to a rigid skeleton. As a result, it was confirmed that the polyimide films of Examples 1 to 8 exhibited not only a low CTE and heat resistance, but also a low dielectric loss tangent, flexibility, and toughness, and were capable of achieving both low dielectric properties and high flexural properties. On the other hand, as can be seen from Table 3, in Comparative Examples 1 and 2, which used a single polymer, a polyimide film having all of the above properties could not be achieved.

[0129] Although the embodiments of the present invention have been described in detail above for the purpose of illustration, the present invention is not limited to the above-described embodiments and various modifications are possible.

Claims

1. A polyimide film comprising a polyimide containing a tetracarboxylic dianhydride residue derived from a tetracarboxylic dianhydride component and a diamine residue derived from a diamine component, The total tetracarboxylic dianhydride residues contained in the film are each selected from the group consisting of a tetracarboxylic dianhydride represented by the following general formula (1): 【Chemical 1】 [In general formula (1), the group Ar represents a divalent group selected from the following formulas:] 【Chemistry 2】 [In the above formula, R １ each independently represents an alkyl group having 1 to 3 carbon atoms, m1 independently represents an integer of 0 to 4, and n1 represents an integer of 0 or 1. and the film contains 20 mol % or more and 80 mol % or less of tetracarboxylic dianhydride residues derived from a tetracarboxylic dianhydride represented by the following general formula (2): 【Chemistry 3】 [In the general formula (2), the linking group X represents a single bond, and R ２ each independently represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 3 carbon atoms, or an alkoxy group; m2 independently represents an integer of 0 to 4; and n2 independently represents an integer of 0 to 2. The diamine residue derived from the diamine represented by the formula (I) is contained in an amount of 20 mol % or more and 80 mol % or less, A polyimide film characterized in that the slope of the plastic deformation region in a stress-strain curve is in the range of 50 MPa or more and less than 500 MPa.

2. In the storage modulus-temperature curve obtained by dynamic viscoelasticity measurement of the polyimide film, the storage modulus at 260°C is 1×10 ７ Pa or more 1×10 ９ 2. The polyimide film according to claim 1, wherein the viscosity is in the range of 0.1 Pa or less.

3. 2. The polyimide film according to claim 1, wherein a loss tangent-temperature curve obtained by measuring the dynamic viscoelasticity of the polyimide film has a peak of the loss tangent derived from the glass transition temperature (Tg1) in the range of 30 to 170°C and a peak of the loss tangent derived from the glass transition temperature (Tg2) in the range of 180 to 400°C.

4. 4. The polyimide film according to claim 3, wherein the difference between Tg1 and Tg2 is 10° C. or more.

5. 2. The polyimide film according to claim 1, wherein the polyimide film has a dielectric loss tangent of 0.003 or less at 10 GHz when measured with a split post dielectric resonator (SPDR) in an environment of a temperature of 24 to 26°C and a humidity of 45 to 55%.

6. A resin film comprising a single layer or a plurality of resin layers, wherein at least one of the resin layers comprises the polyimide film according to claim 1.

7. an insulating resin layer consisting of a single layer or multiple layers; a metal layer laminated on one or both surfaces of the insulating resin layer; A metal-clad laminate comprising:

2. A metal-clad laminate, wherein at least one of said insulating resin layers is made of the polyimide film according to claim 1.

8. A circuit board comprising an insulating resin layer consisting of a single layer or multiple layers, and a conductor circuit layer laminated on one side or both sides of the insulating resin layer, 2. A circuit board, wherein at least one of said insulating resin layers is made of the polyimide film according to claim 1.

9. An electronic device comprising the circuit board according to claim 8.

10. An electronic device comprising the circuit board according to claim 8.

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