Polyimide precursor compositions, polyimide films, and polyimide metal laminates for flexible wiring boards

Abstract

The present invention provides a polyimide precursor composition for flexible wiring boards, the polyimide precursor composition containing a polyimide precursor that has a repeating unit represented by general formula (I). A polyimide film, which has a low dielectric loss tangent in a high frequency region and excellent heat resistance at the same time, can be produced using this polyimide precursor composition. In the formula, more than 0% by mole but less than 30% by mole of the Y1 moiety has a structure represented by formula (1). In formula (1), A represents a structure represented by formula (A); n represents a number of 1 to 4; m represents a number of 0 to 4; B represents an alkyl group having 1 to 6 carbon atoms, or the like; and U represents -CO-O- or -O-CO-.

Description

[Technical Field]

[0001] The present invention relates to a polyimide film for flexible wiring boards, more particularly to a polyimide film suitable for circuit boards in the high-frequency band, and to a polyimide precursor composition for the manufacture of the same. [Background technology]

[0002] Polyimide films are widely used in electronic equipment such as flexible circuit boards and tapes for Tape Automated Bonding (TAB) due to their excellent thermal and electrical properties. In particular, it is known that polyimides with a low coefficient of thermal expansion and high modulus of elasticity can be obtained by using 3,3',4,4'-biphenyltetracarboxylic dianhydride and p-phenylenediamine as the tetracarboxylic acid and diamine components, respectively.

[0003] On the other hand, in recent years, communication devices such as smartphones have begun to utilize high frequency bands around 5 GHz, and even above 10 GHz. For polyimide, a flexible circuit board material that involves high-frequency signal transmission, there is a need for a material with a small dielectric loss tangent, that is, a material with low transmission loss when used as a flexible wiring board.

[0004] Patent Document 1 (JP 2019-210342) proposes a thermoplastic polyimide film with a low dielectric loss tangent, which "contains at least one of p-phenylenebis(trimellitic acid monoester anhydride) or 3,3',4,4'-biphenyltetracarboxylic acid dianhydride as an aromatic acid dianhydride component, and contains at least one of 4,4'-diaminodiphenyl ether, 1,3-bis(4-aminophenoxy)benzene, bis(4-aminophenyl) terephthalate, or 2,2'-bis(trifluoromethyl)benzidine as an aromatic diamine component" (see claim 4).

[0005] Patent Document 2 (JP 2021-74894) describes a multilayer polyimide film having a thermoplastic polyimide resin layer on at least one surface of a non-thermoplastic polyimide resin layer, wherein the non-thermoplastic polyimide resin layer is a reaction product of an acid dianhydride and a diamine, and the tetracarboxylic dianhydride contains 30 mol% or more of a specific ester-type tetracarboxylic dianhydride and / or 30 mol% or more of a specific ester-type diamine (see Claim 1).

[0006] Polyimide films using ester-based diamine compounds, such as the diamine compounds disclosed in the above-mentioned documents 1 and 2, are also disclosed in other documents, including documents 3 to 5. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2019-210342 [Patent Document 2] Japanese Patent Publication No. 2021-74894 [Patent Document 3] Japanese Patent Application Publication No. 11-199668 [Patent Document 4] International Publication No. 2008 / 056808 [Patent Document 5] Japanese Patent Publication No. 2007-246709 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, for polyimide films used in flexible printed circuit board applications, not only the dielectric tangent is small, but also various other properties are required. For example, polyimide films used as the polyimide core layer (heat-resistant layer) of flexible copper-clad laminated boards are required to have high heat resistance. The one disclosed in Patent Document 1 is a thermoplastic polyimide film and cannot be used as a heat-resistant film for polyimide core layers. Patent Document 2 aims to provide a non-thermoplastic polyimide resin layer in a multilayer polyimide film, but its heat resistance is insufficient. Similarly, the polyimide films disclosed in Patent Documents 3 to 5 also lack heat resistance.

[0009] An object of the present invention is to provide a polyimide precursor composition for a flexible printed circuit board and a polyimide film that can produce a polyimide film having a small dielectric tangent in a high-frequency region, excellent heat resistance at the same time, and suitable for manufacturing a flexible printed circuit board.

[0010] Another aspect of the present invention aims to provide a polyimide metal laminate such as a copper-clad laminated board and a flexible printed wiring board processed therefrom, which are based on the polyimide film obtained from the polyimide precursor composition.

Means for Solving the Problems

[0011] Summarizing the main disclosure matters of this application, it is as follows.

[0012] 1. A polyimide precursor composition for a flexible printed circuit board, characterized by containing a polyimide precursor having a repeating unit represented by the following general formula (I).

[0013]

Chemical formula

[0014] [ka] The structure is represented by equation (1), where A is in equation (A):

[0015] [ka] The structure is represented by , where n is an integer from 1 to 4, m is an integer from 0 to 4, B is selected from the group consisting of C1-C6 alkyl groups, C1-C6 alkoxy groups, halogen groups, and C1-C6 fluoroalkyl groups, and U independently represents -CO-O- or -O-CO-.

[0016] 2. The polyimide precursor composition according to item 1, wherein A is a structure selected from the group consisting of a 1,4-phenylene group and a 4,4'-biphenylene group.

[0017] 3. The polyimide precursor composition according to item 1 or 2 above, wherein 50 mol% or more of X1 is a group represented by the following formula (21).

[0018] [ka]

[0019] 4. A polyimide film for flexible wiring boards obtained from the polyimide precursor composition described in any one of items 1 to 3 above.

[0020] 5. A polyimide metal laminate in which the polyimide film described in item 4 above is laminated with a metal foil or metal layer.

[0021] 6. A flexible wiring board in which a metal foil or metal layer of the polyimide metal laminate described in item 5 above is patterned to form wiring. [Effects of the Invention]

[0022] According to the present invention, it is possible to provide a polyimide precursor composition for flexible wiring boards that can produce a polyimide film suitable for the manufacture of flexible wiring boards, which has a small dielectric loss tangent in the high-frequency range and excellent heat resistance. The present invention also provides a polyimide film obtained from this precursor composition.

[0023] Furthermore, according to a different aspect of the present invention, it is possible to provide a polyimide metal laminate, such as a copper-clad laminated substrate, using a polyimide film obtained from the polyimide precursor composition as a base material, and a flexible printed circuit board processed therefrom. [Modes for carrying out the invention]

[0024] <<Polyimide precursor composition>> The polyimide precursor composition for flexible wiring boards contains a polyimide precursor having repeating units represented by general formula (I), and in its distribution form, it contains a solvent, in which the polyimide precursor is dissolved in the solvent.

[0025] The polyimide precursor is given by the following general formula (I):

[0026] [ka] (In general formula I, X1 is a tetravalent aliphatic or aromatic group, Y1 is a divalent aliphatic or aromatic group, and R1 and R2 are independently a hydrogen atom, a C1-C6 alkyl group, or a C3-C9 alkylsilyl group.) It has repeating units represented by . Particularly preferred is a polyamic acid in which R1 and R2 are hydrogen atoms.

[0027] Regarding the polyimide precursor, it will be described by the monomers (tetracarboxylic acid component, diamine component, other components) that give X1 and Y1 in the general formula (I), and then the manufacturing method will be described.

[0028] In this specification, the tetracarboxylic acid component includes tetracarboxylic acids, tetracarboxylic dianhydrides, and other tetracarboxylic acid derivatives such as tetracarboxylic acid silyl esters, tetracarboxylic acid esters, and tetracarboxylic acid chlorides, which are used as raw materials for producing polyimide. Although not particularly limited, for production, it is convenient to use tetracarboxylic dianhydrides. In the following description, an example using tetracarboxylic dianhydrides as the tetracarboxylic acid component will be described. Also, the diamine component is a diamine compound having two amino groups (-NH2), which is used as a raw material for producing polyimide.

[0029] <X1 and Tetracarboxylic Acid Component> X1 may be either an aliphatic group or an aromatic group, but an aromatic group is preferred. X1 is preferably 50 mol% or more, more preferably 70 mol% or more, still more preferably 90 mol% or more (100 mol% is also extremely preferred) and is an aromatic group.

[0030] The following structures can be cited as X1 which is an aromatic group.

[0031] [Chemical formula] (In the formula, Z1 is a direct bond or the following divalent group:

[0032] [Chemical formula] Any of them. However, Z2 in the formula is a divalent organic group, and Z3 and Z4 are each independently an amide bond, an ester bond, or a carbonyl bond, and Z5 is an organic group containing an aromatic ring.)

[0033] Specifically, Z2 can be defined as an aliphatic hydrocarbon group having 2 to 24 carbon atoms, or an aromatic hydrocarbon group having 6 to 24 carbon atoms.

[0034] Specifically, Z5 includes aromatic hydrocarbon groups with 6 to 24 carbon atoms.

[0035] The tetracarboxylic acid component that gives the repeating unit of general formula (I), in which X1 is a tetravalent group having an aromatic ring, is not particularly limited, but includes halogen-unsubstituted aromatic tetracarboxylic acid dianhydrides such as 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,3,3',4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, pyromellitic acid dianhydride, benzophenonetetracarboxylic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, diphenylsulfonetetracarboxylic acid dianhydride, p-terphenyltetracarboxylic acid dianhydride, m-terphenyltetracarboxylic acid dianhydride, 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate); 4,4'-(hexafluoroisopropylidene)diphthalic acid dianhydride, 3,3'-( Suitable examples include halogen-substituted tetracarboxylic dianhydrides such as xafluoroisopropylidene) diphthalic anhydride, 5,5'-[2,2,2-trifluoro-1-[3-(trifluoromethyl)phenyl]ethylidene] diphthalic anhydride, 5,5'-[2,2,3,3,3-pentafluoro-1-(trifluoromethyl)pyropyridene] diphthalic anhydride, 1H-difluoro[3,4-b:3',4'-i]xanthene-1,3,7,9(11H)-tetron, 5,5'-oxybis[4,6,7-trifluoropyromellitic anhydride], 3,6-bis(trifluoromethyl)pyromellitic dianhydride, 4-(trifluoromethyl)pyromellitic dianhydride, 1,4-difluoropyromellitic dianhydride, and 1,4-bis(3,4-dicarboxytrifluorophenoxy)tetrafluorobenzene dianhydride. These may be used individually or in combination of two or more types.

[0036] Among these, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, pyromellitic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate), benzophenonetetracarboxylic dianhydride, and p-terphenyltetracarboxylic dianhydride are particularly preferred.

[0037] In a preferred embodiment of the present invention, X1 contains a structure derived from s-BPDA in an amount of at least 50 mol%, more preferably 60 mol%, even more preferably 70 mol%, and most preferably 80 mol% or more (including 100 mol%). The remaining X1 is preferably an aromatic group, and is preferably selected from, for example, a group derived from 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 4,4'-oxydiphthalic dianhydride, or 1,4-phenylenebis(1,3-dioxo-1,3-dihydroisobenzofuran-5-carboxylate).

[0038] The aliphatic group X1 may be a linear aliphatic group or an alicyclic group, but an alicyclic group is preferred. The alicyclic group X1 is preferably a tetravalent group having an alicyclic structure with 4 to 40 carbon atoms, and more preferably has at least one aliphatic 4 to 12-membered ring, more preferably an aliphatic 4-membered ring or an aliphatic 6-membered ring. The following are examples of tetravalent groups having preferred aliphatic 4-membered rings or aliphatic 6-membered rings.

[0039] [ka] (In the formula, R 31 ~R 38 These are either directly bonded or divalent organic groups. 41 ~R 47 , and R 71 ~R 73represents one selected independently from the group consisting of groups represented by the formulas: -CH2-, -CH=CH-, -CH2CH2-, -O-, -S-. R 48 is an organic group containing an aromatic ring or an alicyclic structure.)

[0040] R 31 R 32 R 33 R 34 R 35 R 36 R 37 R 38 Examples of R

[0041] R 48 Examples of the organic group containing an aromatic ring as R

[0042]

Chemical formula

[0043] Specific examples of W1 include a direct bond, a divalent group represented by the following formula (5), and a divalent group represented by the following formula (6).

[0044]

Chemical formula

[0045] The following are particularly preferred as tetravalent groups having an alicyclic structure.

[0046] [ka]

[0047] Examples of tetracarboxylic acid components that give the alicyclic group X1 include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, [1,1'-bi(cyclohexane)]-3,3',4,4'-tetracarboxylic dianhydride, [1,1'-bi(cyclohexane)]-2,3,3',4'-tetracarboxylic dianhydride, and [1,1'-bi(cyclohexane)]-2,2',3,3' -Tetracarboxylic acid dianhydride, 4,4'-methylenebis(cyclohexane-1,2-dicarboxylic acid anhydride), 4,4'-(propane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic acid anhydride), 4,4'-oxybis(cyclohexane-1,2-dicarboxylic acid anhydride), 4,4'-thiobis(cyclohexane-1,2-dicarboxylic acid anhydride), 4,4'-sulfonylbis(cyclohexane-1,2-dicarboxylic acid anhydride), 4,4'-(dimethylsilanediyl)bis(cyclohexane-1,2-dicarboxylic acid anhydride), 4,4'-(tetrafluoropropane-2,2-diyl)bis(cyclohexane-1,2-dicarboxylic acid anhydride), octahydropentalene-1,3,4,6-tetracarboxylic dianhydride, bicyclo[2.2.1]heptane-2,3,5,6-tetracarboxylic dianhydride, 6-(carboxymethyl)bicyclo[2.2.1]heptane-2,3, 5-tricarboxylic acid dianhydride, bicyclo[2.2.2]octane-2,3,5,6-tetracarboxylic acid dianhydride, bicyclo[2.2.2]octa-5-ene-2,3,7,8-tetracarboxylic acid dianhydride, tricyclo[4.2.2.02,5]decane-3,4,7,8-tetracarboxylic acid dianhydride, tricyclo[4.2.2.02,5]deca-7-ene-3,4,9,10-tetracarboxylic acid dianhydride, 9-oxatricyclo[4.2.1.Examples include [02,5]nonane-3,4,7,8-tetracarboxylic dianhydride, norbornane-2-spiro-α-cyclopentanone-α'-spiro-2''-norbornane-5,5'',6,6''-tetracarboxylic dianhydride, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2c,3c,6c,7c-tetracarboxylic dianhydride, (4arH,8acH)-decahydro-1t,4t:5c,8c-dimethanonaphthalene-2t,3t,6c,7c-tetracarboxylic dianhydride, decahydro-1,4-ethano-5,8-methanonaphthalene-2,3,6,7-tetracarboxylic dianhydride, and tetradecahydro-1,4:5,8:9,10-trimethanoanthracene-2,3,6,7-tetracarboxylic dianhydride. These can be used individually or in combination.

[0048] Examples of tetracarboxylic acid components that give the chain-like aliphatic group X1 include straight-chain or branched tetracarboxylic acid dianhydrides with approximately 4 to 10 carbon atoms, such as 1,2,3,4-butanetetracarboxylic acid dianhydride and 1,2,3,4-pentanetetracarboxylic acid dianhydride.

[0049] Y1 is at least given by equation (1): [ka] It contains a group represented by formula (A):

[0050] [ka] (n is an integer from 1 to 4, m is an integer from 0 to 4, and B represents one selected from the group consisting of alkyl groups with 1 to 6 carbon atoms, alkoxy groups with 1 to 6 carbon atoms, halogen groups, and fluoroalkyl groups with 1 to 6 carbon atoms.) This represents a structure represented by . n is preferably 1 to 3, more preferably 1 or 2. m is preferably 0 or 1. Examples of A include 1,4-phenylene, 1,3-phenylene, 4,4'-biphenylene, 3,4'-biphenylene, 3,3'-biphenylene, 4,4"-p-terphenylene, etc. 1,4-phenylene, 4,4'-biphenylene, 4,4"-p-terphenylene, etc., bonded at the para position are particularly preferred.

[0051] Preferably, U represents -CO-O- on one side and -O-CO- on the other. That is, the preferred structure of formula (1) is represented by formula (1-1) or formula (1-2).

[0052] [ka]

[0053] [ka]

[0054] The positional relationship between U in equation (1) and the bond (the relationship between U and N in equation (I)) may be ortho, meta, or para, but is preferably para.

[0055] Examples of diamine compounds that give the group of formula (1) include (bis(4-aminophenyl) terephthalate (abbreviation BPTP), bis(4-aminophenyl)biphenyl-4,4'-dicarboxylate (abbreviation APBP), and [4-(4-aminobenzoyl)oxyphenyl]4-aminobenzoate (abbreviation ABHQ).

[0056] The proportion of the group of formula (1) in Y1 is greater than 0 mol% and less than 30 mol%, more preferably 10 mol% or more, even more preferably 15 mol% or more, and preferably less than 25 mol%. Within this range, a polyimide film is obtained in which low dielectric loss tangent and heat resistance are well balanced.

[0057] Y1 other than formula (1) may be either an aliphatic group or an aromatic group, but an aromatic group is preferred.

[0058] Examples of aromatic groups Y1 include the following:

[0059] [ka] (In the formula, W1 is a direct bond or a divalent organic group, n 11 ~n 13 Each of these independently represents an integer from 0 to 4, and R 51 , R 52 , R 53 These are, independently, an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group, or a trifluoromethyl group.

[0060] Specifically, W1 can be a direct bond, a divalent group represented by formula (5) below, or a divalent group represented by formula (6) below.

[0061] [ka] (R in equation (6)) 61 ~R 68 Each of these independently represents either a directly bonded group or a divalent group represented by formula (5) above.

[0062] Examples of diamine components that give Y1, a divalent group having an aromatic ring, include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, 3,3'-dihydroxy-4,4'-diaminobiphenyl, bis(4-amino-3-carboxyphenyl)methane, benzidine, 3,3'-diamino-biphenyl, 4,4"-diamino-p-terphenyl, 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, m-tolidine, 4,4'-diaminobenzanilide, and 3,4'-diaminobenzane. Suanilide, N,N'-bis(4-aminophenyl)terephthalamide, N,N'-p-phenylenebis(p-aminobenzamide), 4-aminophenoxy-4-diaminobenzoate, bis(4-aminophenyl)terephthalate, biphenyl-4,4'-dicarboxylate bis(4-aminophenyl)ester, p-phenylenebis(p-aminobenzoate), bis(4-aminophenyl)-[1,1'-biphenyl]-4,4'-dicarboxylate, [1,1'-biphenyl]-4,4'-diylbis(4-aminobenzoate), 4,4'-oxy Sidianiline (also known as 4,4'-diaminodiphenyl ether), 3,4'-oxydianiline, 3,3'-oxydianiline, p-methylenebis(phenylenediamine), 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, 2,2-bis(4-(4-aminophenoxy) phenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, bis(4-aminophenyl)sulfone, 3,3'-bis(trifluoromethyl)benzidine, 3,3'-bis((aminophenoxy)phenyl)propane, 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, bis(4-(4-aminophenoxy)diphenyl)sulfone, bis(4-(3-aminophenoxy)diphenyl)sulfone, octafluorobenzidine, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,Examples include 3'-dichloro-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 2,4-bis(4-aminoanilino)-6-amino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-methylamino-1,3,5-triazine, 2,4-bis(4-aminoanilino)-6-ethylamino-1,3,5-triazine, and 2,4-bis(4-aminoanilino)-6-anilino-1,3,5-triazine. Examples of diamine components that give the repeating unit of general formula (I), in which Y1 is a divalent group having an aromatic ring containing a fluorine atom, include 2,2'-bis(trifluoromethyl)benzidine, 3,3'-bis(trifluoromethyl)benzidine, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, and 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane. In addition, preferred diamine compounds include 9,9-bis(4-aminophenyl)fluorene, 4,4'-(((9H-fluorene-9,9-diyl)bis([1,1'-biphenyl]-5,2-diyl))bis(oxy))diamine, [1,1':4',1”-terphenyl]-4,4”-diamine, and 4,4'-([1,1'-binaphthalene]-2,2'-diylbis(oxy))diamine. The diamine components may be used individually or in combination.

[0063] Examples of Y1, which has an alicyclic structure, include the following:

[0064] [ka] (In the formula, V1 and V2 are each independently directly bonded or are divalent organic groups, n 21 ~n 26 Each of these independently represents an integer from 0 to 4, and R 81 ~R 86 Each of these is independently an alkyl group having 1 to 6 carbon atoms, a halogen group, a hydroxyl group, a carboxyl group, or a trifluoromethyl group, and R 91, R 92 , R 93 (Each of these groups is independently selected from the group consisting of groups represented by the formulas: -CH2-, -CH=CH-, -CH2CH2-, -O-, and -S-.)

[0065] Specifically, V1 and V2 include direct bonds and divalent groups represented by formula (5) above.

[0066] Examples of diamine components that give Y1 having an alicyclic structure include 1,4-diaminocyclohexane, 1,4-diamino-2-methylcyclohexane, 1,4-diamino-2-ethylcyclohexane, 1,4-diamino-2-n-propylcyclohexane, 1,4-diamino-2-isopropylcyclohexane, 1,4-diamino-2-n-butylcyclohexane, 1,4-diamino-2-isobutylcyclohexane, 1,4-diamino-2-sec-butylcyclohexane, 1,4-diamino-2-tert-butylcyclohexane, 1,2-diaminocyclohexane, 1,3-diaminocyclobutane, and 1,4-bis(aminomethyl Examples include cyclohexane, 1,3-bis(aminomethyl)cyclohexane, diaminobicycloheptane, diaminomethylbicycloheptane, diaminooxybicycloheptane, diaminomethyloxybicycloheptane, isophoronediamine, diaminotricyclodecane, diaminomethyltricyclodecane, bis(aminocyclohexyl)methane, bis(aminocyclohexyl)isopropylidene, 6,6'-bis(3-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobindan, and 6,6'-bis(4-aminophenoxy)-3,3,3',3'-tetramethyl-1,1'-spirobindan. The diamine components may be used individually or in combination of multiple types.

[0067] Other than formula (1), Y1 is preferably selected to give a polyimide with high heat resistance, and an aromatic group is preferred. Examples of diamine compounds include p-phenylenediamine, 4,4”-diamino-p-terphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, and 1,3-bis(4-aminophenoxy)benzene.

[0068] In particular, p-phenylenediamine and / or 4,4"-diamino-p-terphenyl are present in amounts of 40 mol% or more and less than 100 mol%, preferably 50 mol% or more and less than 100 mol%, relative to the total diamine components.

[0069] As described above, the proportion of the diamine compound that gives the group of formula (1) is more than 0 mol% and less than 30 mol%, more preferably 10 mol% or more, even more preferably 15 mol% or more, preferably 25 mol% or less, and more preferably less than 25 mol%. Therefore, p-phenylenediamine and / or 4,4”-diamino-p-terphenyl, and other diamine compounds such as 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, 1,3-bis(4-aminophenoxy)benzene, etc. are used so that the total is 100 mol%.

[0070] Polyimide precursor compositions for flexible wiring boards are obtained by reacting a tetracarboxylic acid component with a diamine component in a solvent. This reaction is carried out at a relatively low temperature, for example, 100°C or below, preferably 80°C or below, using approximately equimolar amounts of the tetracarboxylic acid component (tetracarboxylic dianhydride) and the diamine component. Although not limited, the reaction temperature is usually 25°C to 100°C, preferably 25°C to 80°C, more preferably 30°C to 80°C, and the reaction time is, for example, about 0.1 to 72 hours, preferably about 2 to 60 hours. The reaction can be carried out in an air atmosphere, but is usually suitably carried out in an inert gas atmosphere, preferably a nitrogen gas atmosphere.

[0071] Furthermore, when we say that the tetracarboxylic acid component (tetracarboxylic dianhydride) and the diamine component are approximately equimolar, specifically, the molar ratio [tetracarboxylic acid component / diamine component] is about 0.90 to 1.10, preferably about 0.95 to 1.05.

[0072] The solvent used when preparing the polyimide precursor composition is preferably water or an aprotic solvent such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, or dimethyl sulfoxide. Any type of solvent can be used as long as it dissolves the raw material monomer components and the resulting polyimide precursor, so there are no particular limitations on its structure. Preferably used solvents include water, amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and N-ethyl-2-pyrrolidone, cyclic ester solvents such as γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, ε-caprolactone, and α-methyl-γ-butyrolactone, carbonate solvents such as ethylene carbonate and propylene carbonate, glycol solvents such as triethylene glycol, phenol solvents such as m-cresol, p-cresol, 3-chlorophenol, and 4-chlorophenol, acetophenone, 1,3-dimethyl-2-imidazolidinone, sulfolane, and dimethyl sulfoxide. Furthermore, other common organic solvents such as phenol, o-cresol, butyl acetate, ethyl acetate, isobutyl acetate, propylene glycol methyl acetate, ethyl cellosolve, butyl cellosolve, 2-methyl cellosolve acetate, ethyl cellosolve acetate, butyl cellosolve acetate, tetrahydrofuran, dimethoxyethane, diethoxyethane, dibutyl ether, diethylene glycol dimethyl ether, methyl isobutyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methyl ethyl ketone, acetone, butanol, ethanol, xylene, toluene, chlorobenzene, turpentine, mineral spirits, and petroleum naphtha-based solvents can also be used. Note that multiple solvents can be used in combination.

[0073] In the production of the polyimide precursor composition, although not particularly limited, the monomer and solvent are charged at a concentration such that the solid content concentration (polyimide equivalent mass concentration) of the polyimide precursor is, for example, 5 to 45% by mass, and the reaction is carried out.

[0074] The viscosity of the polyimide precursor composition solution should be appropriately selected depending on the intended use (coating, casting, etc.) and the purpose of manufacture. For example, a polyamic acid (polyimide precursor) solution is preferable from the standpoint of ease of handling if its rotational viscosity, measured at 30°C, is approximately 0.1 to 5000 poise, particularly 0.5 to 2000 poise, and even more preferably 1 to 2000 poise.

[0075] The polyimide precursor composition may be obtained by using the reaction solution of the tetracarboxylic acid component and the diamine component as is, or by concentrating it or diluting it with a solvent as needed. Therefore, the solvent contained in the polyimide precursor composition may be the solvent used in the reaction between the tetracarboxylic acid component and the diamine component. The solvent added as needed may be the same as or different from the reaction solvent.

[0076] The polyimide precursor composition may optionally contain an imidation catalyst, an organophosphorus-containing compound, or inorganic fine particles if thermal imidation is performed. The polyamic acid solution may optionally contain a cyclization catalyst, a dehydrating agent, or inorganic fine particles if chemical imidation is performed.

[0077] Examples of imidation catalysts include substituted or unsubstituted nitrogen-containing heterocyclic compounds, N-oxide compounds of said nitrogen-containing heterocyclic compounds, substituted or unsubstituted amino acid compounds, aromatic hydrocarbon compounds having a hydroxyl group, or aromatic heterocyclic compounds. Particularly suitable are lower alkyl-substituted or aromatic group-substituted imidazoles such as 1,2-dimethylimidazole, N-methylimidazole, N-benzyl-2-methylimidazole, 2-methylimidazole, 2-ethyl-4-methylimidazole, and 2-phenylimidazole, benzimidazoles such as 5-methylbenzimidazole, isoquinoline, 3,5-dimethylpyridine, 3,4-dimethylpyridine, 2,5-dimethylpyridine, 2,4-dimethylpyridine, and 4-n-propylpyridine. The amount of imidation catalyst used is preferably 0.01 to 2 equivalents, particularly 0.02 to 1 equivalent, relative to the amide acid units of the polyamic acid. The use of an imidation catalyst can improve the physical properties of the resulting polyimide film, particularly its elongation and edge tear resistance.

[0078] Examples of organophosphorus-containing compounds include phosphate esters such as monocaproyl phosphate, monooctyl phosphate, monolauryl phosphate, monomyristyl phosphate, monocetyl phosphate, monostearyl phosphate, monophosphate of triethylene glycol monotridecyl ether, monophosphate of tetraethylene glycol monolauryl ether, monophosphate of diethylene glycol monostearyl ether, dicaproyl phosphate, dioctyl phosphate, dicapryl phosphate, dilauryl phosphate, dimyristyl phosphate, dicetyl phosphate, distearyl phosphate, diphosphate of tetraethylene glycol mononeopentyl ether, diphosphate of triethylene glycol monotridecyl ether, diphosphate of tetraethylene glycol monolauryl ether, and diphosphate of diethylene glycol monostearyl ether, as well as amine salts of these phosphate esters. Examples of amines include ammonia, monomethylamine, monoethylamine, monopropylamine, monobutylamine, dimethylamine, diethylamine, dipropylamine, dibutylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, monoethanolamine, diethanolamine, and triethanolamine.

[0079] Examples of cyclization catalysts include aliphatic tertiary amines such as trimethylamine and triethylenediamine, aromatic tertiary amines such as dimethylaniline, and heterocyclic tertiary amines such as isoquinoline, pyridine, α-picoline, and β-picoline.

[0080] Examples of dehydrating agents include aliphatic carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride, and aromatic carboxylic acid anhydrides such as benzoic anhydride.

[0081] Examples of inorganic fine particles include inorganic oxide powders such as fine titanium dioxide powder, silicon dioxide (silica) powder, magnesium oxide powder, aluminum oxide (alumina) powder, and zinc oxide powder; inorganic nitride powders such as fine silicon nitride powder and titanium nitride powder; inorganic carbide powders such as silicon carbide powder; and inorganic salt powders such as fine calcium carbonate powder, calcium sulfate powder, and barium sulfate powder. Two or more of these inorganic fine particles may be used in combination. Known means can be applied to uniformly disperse these inorganic fine particles.

[0082] <<Manufacturing of Polyimide Film>> The polyimide precursor composition of the present invention can be used to produce single-layer or multi-layer polyimide films.

[0083] Polyimide films can be manufactured by known methods, and examples of methods for manufacturing single-layer polyimide films include the following (1) and (2). (1) A method for obtaining a polyimide film by casting or coating a polyimide precursor composition onto a support, and then heating it on the support to complete the imidization process. (2) A method to obtain a polyimide film by casting or coating a polyimide precursor composition onto a support, heating it to produce a self-supporting film (gel film) in a semi-cured or earlier dry state, peeling the self-supporting film from the support, and heating the self-supporting film while holding its edges with a tenter device or the like to carry out desolvation and imidization.

[0084] The method described in (2) above is suitable for continuously manufacturing long polyimide films.

[0085] The single-layer polyimide film produced using the polyimide precursor composition of the present invention exhibits excellent heat resistance, with a glass transition temperature (Tg) preferably 260°C or higher, more preferably 270°C or higher, even more preferably 280°C or higher, and even more preferably 290°C or higher. The 5% weight loss temperature (Td5) is preferably 550°C or higher, more preferably 555°C or higher, and even more preferably 560°C or higher. Furthermore, the dielectric loss tangent at a frequency of 10 GHz and humidity of 60% RH is preferably less than 0.0055, more preferably 0.0053 or lower, even more preferably 0.0051 or lower, even more preferably 0.0045 or lower, even more preferably 0.0040 or lower, and even more preferably 0.0036 or lower.

[0086] The linear thermal expansion coefficient (CTE) of the single-layer polyimide film of the present invention is preferably 20 ppm / K or less, more preferably 16 ppm / K or less, and even more preferably 13 ppm / K or less.

[0087] Methods for manufacturing multilayer polyimide films include the following methods (3) and (4). (3) A method for obtaining a polyimide film by casting or coating a polyimide precursor composition onto a support to produce a self-supporting film, casting or coating a second or more layer of polyimide precursor composition onto one or both sides of the self-supporting film, and then heating to complete the imidization (if necessary, by first producing a self-supporting film and then holding the self-supporting film in a tenter device). (4) A method for obtaining a polyimide film by simultaneously casting or coating two or more polyimide precursor compositions onto a support, for example by co-extrusion, and then heating to complete imidization (if necessary, by first producing a self-supporting film and then holding the self-supporting film in a tenter device).

[0088] The multilayer polyimide film (or polyimide layer) of the present invention has excellent heat resistance, and the solder heat resistance temperature is preferably 280°C or higher, more preferably 290°C or higher. Furthermore, the dielectric loss tangent is preferably less than 0.0055, more preferably 0.0053 or lower, even more preferably 0.0051 or lower, even more preferably 0.0048 or lower, and even more preferably 0.0045 or lower at a frequency of 10 GHz and a humidity of 60% RH.

[0089] The linear thermal expansion coefficient (CTE) of the multilayer polyimide film of the present invention is preferably 25 ppm / K or less, more preferably 23 ppm / K or less, and even more preferably 20 ppm / K or less.

[0090] Examples of multilayer polyimide films include a two-layer structure of a heat-fusible PI layer / heat-resistant PI layer, and a three-layer structure of a heat-fusible PI layer / heat-resistant PI layer / heat-fusible PI layer (PI stands for polyimide). The polyimide precursor composition of the present invention is suitably used as the heat-resistant polyimide layer of a multilayer polyimide film.

[0091] <<Heat-fusible polyimide layer (heat-fusible PI layer)>> The heat-fusible polyimide layer of the multilayer polyimide film is formed from a heat-fusible polyimide obtained from a tetracarboxylic acid component and a diamine component. The heat-fusible polyimide preferably uses at least one tetracarboxylic acid dianhydride selected from 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 2,3,3',4'-biphenyltetracarboxylic acid dianhydride (these two components are collectively referred to as "biphenyltetracarboxylic acid dianhydride"), and pyromellitic acid dianhydride as the tetracarboxylic acid component, in an amount of 50 to 100 mol% of the total tetracarboxylic acid component. The total amount of these tetracarboxylic acid components is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more of the total tetracarboxylic acid component.

[0092] When pyromellitic dianhydride is the main component as the tetracarboxylic acid component, the pyromellitic dianhydride is preferably 50 mol% or more and 90 mol% or less, more preferably 65 mol% or more, even more preferably 70 mol% or more, more preferably 85 mol% or less, and even more preferably 80 mol% or less. Biphenyltetracarboxylic acid dianhydride is preferably 10 mol% or more and 50 mol% or less, more preferably 15 mol% or more, even more preferably 20 mol% or more, even more preferably 35 mol% or less, and even more preferably 30 mol% or less.

[0093] When biphenyltetracarboxylic dianhydride is the main component of the tetracarboxylic acid, the amount of biphenyltetracarboxylic dianhydride is preferably 50 mol% or more and 100 mol% or less, more preferably 70 mol% or more, and even more preferably 90 mol% or more. The amount of pyromellitic dianhydride is preferably 0 mol% or more and 50 mol% or less, more preferably 30 mol% or less, and even more preferably 10 mol% or less.

[0094] When biphenyltetracarboxylic dianhydride is considered as 100 mol%, the ratio is preferably 50 mol% or more and 100 mol% or less for 3,3',4,4'-biphenyltetracarboxylic dianhydride, more preferably 70 mol% or more and more preferably 90 mol% or less, and 0 mol% or more and 50 mol% or less for 2,3,3',4'-biphenyltetracarboxylic dianhydride, more preferably 10 mol% or more and more preferably 30 mol% or less.

[0095] The tetracarboxylic acid components can be the three tetracarboxylic acid components mentioned above, in combination with other tetracarboxylic acid components. Examples of other tetracarboxylic acid components that can be used in combination include 3,3',4,4'-benzophenone tetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl) ether dianhydride, bis(3,4-dicarboxyphenyl) sulfide dianhydride, bis(3,4-dicarboxyphenyl) sulfone dianhydride, bis(3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl) propane dianhydride, and 1,4-hydroquinone dibenzoate-3,3',4,4'-tetracarboxylic dianhydride. The tetracarboxylic acid components used in combination can be used individually or in combination of two or more.

[0096] Furthermore, it is preferable that the heat-fusible polyimide uses a diamine represented by the following chemical formula (13) as the diamine component in an amount of 50 to 100 mol% of the total diamine components. The total amount of these diamine components is preferably 70 mol% or more, more preferably 80 mol% or more, and even more preferably 90 mol% or more of the total diamine components.

[0097] [ka] [In equation (13), X represents O, CO, COO, OCO, C(CH3)2, CH2, SO2, S, or a direct bond, and may have two or more bonding modes, and m represents an integer from 0 to 4.]

[0098] Examples of diamines represented by the chemical formula (13) include 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, 3,3'-diaminobenzophenone, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]sulfide, and bis[4-(4-aminophenoxy)phenyl]sulfide. Examples include bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, bis(4-aminophenyl)terephthalate, bis(4-aminophenyl)biphenyl-4,4'-dicarboxylate, and [4-(4-aminobenzoyl)oxyphenyl]4-aminobenzoate. The diamine components may be used individually or in combination of multiple types.

[0099] It is preferable that the heat-fusible polyimide constituting the heat-fusible polyimide layer is amorphous, from the viewpoint of improving the peel strength between the heat-fusible polyimide layer and the heat-resistant polyimide layer, and from improving the peel strength between the heat-fusible polyimide layer and the copper foil. Amorphous heat-fusible polyimide means that it has a glass transition temperature, but no melting point is observed. To produce a heat-fusible polyimide layer composed of amorphous heat-fusible polyimide, for example, a method such as using a compound having an ether bond as the tetracarboxylic acid component or diamine component may be employed. Furthermore, from the viewpoint of improving the heat resistance of the resulting heat-fusible polyimide film, the glass transition temperature of the heat-fusible polyimide constituting the heat-fusible polyimide layer is preferably 250°C to 320°C, and more preferably 270°C to 300°C. The method for measuring the glass transition temperature will be described in detail in the examples below.

[0100] <<Polyimide metal laminate>> Using the polyimide precursor composition or polyimide film of the present invention, a polyimide metal laminate can be produced in which a polyimide film (or layer) and a metal foil (or layer) are laminated. Examples of methods for producing the polyimide metal laminate include the following: (i) A method of laminating a polyimide film and a substrate (e.g., metal foil) by applying pressure or heat-pressure directly or via an adhesive. (ii) A method of directly forming a metal layer on a polyimide film by a dry method (metallizing such as vacuum deposition or sputtering) and / or a wet method (plating), (iii) A method of coating a polyimide precursor composition onto a substrate such as metal foil, and then drying and imidizing it.

[0101] In (i) above, when a polyimide film and a substrate (e.g., metal foil) are directly laminated, a multilayer polyimide film having a heat-sealable layer on its surface, such as a two-layer structure of a heat-sealable PI layer / heat-resistant PI layer or a three-layer structure of a heat-sealable PI layer / heat-resistant PI layer / heat-sealable PI layer, is preferably used.

[0102] In (i) above, when laminating a polyimide film and a substrate (e.g., metal foil) via an adhesive, there are no particular restrictions on the adhesive as long as it is a heat-resistant adhesive used in the electronics field. Examples include polyimide-based adhesives, epoxy-modified polyimide-based adhesives, phenol resin-modified epoxy resin adhesives, epoxy-modified acrylic resin-based adhesives, and epoxy-modified polyamide-based adhesives. This heat-resistant adhesive layer can be provided by any method used in the electronics field. For example, the adhesive solution may be applied to the polyimide film or molded body and dried, or it may be bonded with a separately formed film-like adhesive.

[0103] In (i) and (iii) above, the substrate can be a single metal or alloy, such as metal foil or metal plating layer of copper, aluminum, gold, silver, nickel, or stainless steel (preferably, many known techniques such as a vapor-deposited metal underlayer-metal plating layer or a chemical metal plating layer can be applied). Preferably, rolled copper foil, electrolytic copper foil, or copper plating layer can be used. The thickness of the metal foil is not particularly limited, but 0.1 μm to 10 mm, more preferably 1 to 50 μm, and especially preferably 5 to 18 μm.

[0104] As the dry method (metallizing method) used in (ii) above, known methods such as vacuum deposition, sputtering, ion plating, and electron beam can be used. As the metal used in the metallizing method, metals such as copper, nickel, chromium, manganese, aluminum, iron, molybdenum, cobalt, tungsten, vanadium, titanium, and tantalum, or alloys thereof, or oxides of those metals, or carbides of those metals can be used, but are not particularly limited to these materials. The thickness of the formed metal layer is, for example, 1 nm to 500 nm, and a metal plating layer of copper, tin, etc. can be provided on this surface to a thickness of, for example, 1 μm to 40 μm by known wet plating methods such as electroplating or electroless plating.

[0105] The wet plating method used in (ii) above can be any known plating method, such as electroplating or electroless plating, or a combination of these. The metal used in the wet plating method is not limited in any way, as long as it is a metal that can be wet plated.

[0106] The thickness of the metal layer formed by the wet plating method can be appropriately selected depending on the intended use, preferably in the range of 0.1 to 50 μm, and more preferably in the range of 1 to 30 μm, for practical use. The number of metal layers formed by the wet plating method can be appropriately selected depending on the intended use, and may be one layer, two layers, or three or more layers.

[0107] Examples of conventional wet plating methods include the Elf Seed process manufactured by Ebara Eugelite Co., Ltd., and the Catalyst Bond process, a surface treatment process of Nikko Metals Co., Ltd., which is followed by electroless copper plating.

[0108] The polyimide film of the present invention has a low dielectric loss tangent in the high-frequency range and excellent heat resistance, so the polyimide metal laminate of the present invention (including both laminates in which a film and a metal layer are laminated via an adhesive layer, and laminates in which a metal layer is formed directly on the film) can be suitably used for flexible wiring board applications. That is, a flexible wiring board can be manufactured by patterning the metal foil (or metal layer) of the polyimide metal laminate using a known method to form wiring.

[0109] The polyimide precursor composition, polyimide film, or polyimide metal laminate of the present invention can be used not only for flexible wiring board applications but also for applications such as TAB tapes, COF tapes, flexible heaters, resistor substrates, insulating films, and protective films. [Examples]

[0110] The present invention will be described in further detail below with reference to examples and comparative examples.

[0111] The following abbreviations will be used below. <Tetracarboxylic acids> s-BPDA: 3,3',4,4'-biphenyltetracarboxylic acid dianhydride PMDA: Pyromelit acid dianhydride ODPA: Oxydiphthalic acid dianhydride (also known as bis(3,4-dicarboxyphenyl) ether dianhydride) TAHQ: 1,4-Phenylenebis(1,3-Dioxo-1,3-Dihydroisobenzofuran-5-carboxylate) (also known as p-Phenylenebis(trimellitate anhydride))

[0112] <Diamines> PPD: p-phenylenediamine DATP: 4,4”-diamino-p-terphenyl m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl (also known as m-tolidine) BPTP: Bis(4-aminophenyl) terephthalate APBP: Bis(4-aminophenyl)biphenyl-4,4'-dicarboxylate BAPB:4,4'-Bis(4-aminophenoxy)biphenyl TPE-R: 1,3-bis(4-aminophenoxy)benzene BAPP: 2,2-Bis[4-(4-aminophenoxy)phenyl]propane <Other> DMAc: N,N-dimethylacetamide

[0113] Table 1 shows the structural formulas of the tetracarboxylic acid and diamine components.

[0114] [Table 1]

[0115] <Evaluation of polyimide films> [Glass transition temperature (Tg)] Using an RSA G2 dynamic viscoelasticity analyzer manufactured by TA INSTRUMENTS, the dynamic viscoelasticity of a polyimide film was measured under conditions of a heating rate of 10°C / min and a frequency of 1 Hz, and the peak temperature of tanδ was defined as the glass transition temperature.

[0116] [Dielectric Loss Tangent] A split-cylinder resonator 10GHz CR-710 (manufactured by EM Lab Co., Ltd.) was used as the measuring device, and the dielectric loss tangent of the polyimide film was measured under the following conditions. Measurement frequency: 10GHz Measurement conditions: temperature 25±2℃, humidity 60±2%RH Measurement sample: A sample that had been left standing for 48 hours under the above measurement conditions was used.

[0117] [5% weight loss temperature (Td5)] A polyimide film with a thickness of approximately 25 μm was used as a test specimen, and a calorimeter (Q5000IR) manufactured by TA INSTRUMENTS was used to heat the film from 30°C to 700°C in a nitrogen stream at a heating rate of 10°C / min. From the obtained weight curve, the temperature at which the weight at 150°C was set to 100% was determined.

[0118] [Solder heat resistance test] Copper foil (Fukuda Metal Foil & Powder Industry Co., Ltd., CF-T49A-DS-HD2, 12μm thick) is layered on both sides of a multilayer polyimide film, and heated at a temperature of 360℃. give A copper-clad laminate was obtained by thermocompression bonding with heat for 2 minutes, a press pressure of 3 MPa, and a press time of 2 minutes, resulting in copper foil being laminated on both sides of a multilayer polyimide film. A resist was printed on a portion of one side and the entire other side of this copper-clad laminate, and the laminate was immersed in an etching solution at 30°C for 20-30 minutes, resulting in a laminate where the metal layer on one side was partially etched and the copper foil remained entirely on the other side. The obtained laminate was dried at 80°C for 30 minutes and conditioned in an environment of 85°C-85%RH for more than 24 hours. This sample was floated in a solder bath at various temperatures for 60 seconds, and the presence or absence of foaming of the sample was checked. The highest temperature at which foaming was not observed was defined as the solder heat resistance temperature.

[0119] <Example 5> [Preparation of polyimide precursor composition] DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen inlet tube, and then PPD and BPTP were added as diamine components. Subsequently, s-BPDA was added as a tetracarboxylic dianhydride component in equimolar amounts with the diamine components and reacted to obtain a polyimide precursor composition with a monomer concentration of 18% by mass and a solution viscosity of 1800 poise at 30°C. The molar ratio of PPD to BPTP was 80:20.

[0120] [Manufacturing of polyimide film] A polyimide precursor composition was cast as a thin film onto a glass plate, heated in an oven at 120°C for 12 minutes, and peeled off the glass plate to obtain a self-supporting film. The four sides of this self-supporting film were fixed with a pin tenter, and the film was gradually heated in a heating furnace from 150°C to 450°C (maximum heating temperature was 450°C) to remove the solvent and perform imidization, thereby obtaining a polyimide film.

[0121] The thickness of the polyimide film is approximately 25 μm. The evaluation results are shown in Table 2.

[0122] <Examples 1-4, 6-19, Comparative Examples 1-6> In Example 5, a polyimide precursor composition was prepared in the same manner as in Example 5, except that the tetracarboxylic acid component and the diamine component were changed to the compounds and amounts (molar ratios) shown in Table 2. Subsequently, a polyimide film was manufactured in the same manner as in Example 5, and the film properties were evaluated. The evaluation results are shown in Table 2.

[0123] [Table 2]

[0124] Table 2 shows that the addition of BPTP reduces the dielectric loss tangent. When the amount of BPTP added is in the range of 30 mol% or more of the diamine component, the decrease in glass transition temperature (Tg) is greater compared to the comparative example without BPTP. The addition of APBP also shows a reduction in the dielectric loss tangent.

[0125] As described above, the present invention has been shown to satisfy in a balanced manner the characteristics required for the manufacture of flexible copper-clad laminates, namely dielectric loss tangent and glass transition temperature (Tg).

[0126] <Multilayer polyimide film> A multilayer polyimide film having a three-layer structure of a heat-sealable PI layer / heat-sealable PI layer / heat-sealable PI layer was manufactured, with the polyimide film of the present invention as the heat-resistant PI layer (core layer). The polyimide precursor composition for the production of the core layer was prepared in the same manner as in Example 5, except that the tetracarboxylic acid component and the diamine component were changed to the compounds and amounts (molar ratios) shown in Table 3.

[0127] [Preparation of polyimide precursor compositions that yield heat-fusible polyimides] DMAc was added to a reaction vessel equipped with a stirrer and a nitrogen inlet tube, and then BAPP was added as the diamine component. Subsequently, s-BPDA and PMDA were added as tetracarboxylic dianhydride components in approximately equimolar amounts with the diamine component and reacted to obtain a polyimide precursor composition with a monomer concentration of 18% by mass and a solution viscosity of 800 poise at 30°C. The molar ratio of s-BPDA to PMDA was 30:70.

[0128] [Manufacturing of polyimide film] From a three-layer extrusion die, a polyimide precursor composition for core layer production and a polyimide precursor composition for heat-fusible layer formation were extruded and cast onto the upper surface of a smooth metal support in the order of a heat-fusible PI layer / heat-resistant PI layer / heat-fusible PI layer, forming a thin film. The thin film was continuously dried with hot air at 140°C to form a self-supporting film. After peeling the self-supporting film from the support, it was gradually heated in a heating furnace from 200°C to 390°C (maximum heating temperature 390°C) to remove the solvent and imidize, producing a three-layer polyimide film with a thickness of 50 μm (5.7 μm / 38.6 μm / 5.7 μm).

[0129] Table 3 shows the dielectric loss tangent measurement and solder heat resistance test results for the manufactured multilayer polyimide films.

[0130] [Table 3]

[0131] These results indicate that even when the polyimide film with the composition of the present invention is used as a heat-resistant PI layer (core layer), it exhibits low dielectric loss tangent and excellent solder heat resistance, making it ideal for the manufacture of flexible copper-clad laminated substrates. [Industrial applicability]

[0132] Polyimide films produced from the polyimide precursor composition of the present invention can be suitably used for flexible wiring substrate applications.

Claims

1. A polyimide precursor composition for flexible wiring boards, characterized by containing a polyimide precursor having repeating units represented by the following general formula (I). 【Chemistry 1】 {In general formula (I), X １ Y is a tetravalent aliphatic or aromatic group. １ R is a divalent aliphatic or aromatic group, １ and R ２ These are, independently of each other, a hydrogen atom, a C1-C6 alkyl group, or a C3-C9 alkylsilyl group, however, X １ For amounts of 50 mol% or more, see formula (21) below: 【Chemistry 2】 The base is represented by the following formulas (22), (23), (24), (25), and (26): 【Transformation 3】 It includes one or more groups selected from the group consisting of groups represented by Y １ For amounts greater than 0 mol% and less than 30 mol%, use formula (1): 【Chemistry 4】 The structure is represented by formula (1), where A represents a phenylene group, U independently represents -CO-O- or -O-CO-, and 50 mol% or more of Y1 is selected from the groups represented by the following formulas (31) or (32), provided that in the case of the group represented by formula (31), it further includes at least one group selected from the group consisting of the groups represented by (33), (34), and (35). 【Transformation 5】 ｝

2. A polyimide precursor composition for flexible wiring boards, characterized by containing a polyimide precursor having repeating units represented by the following general formula (I). 【Transformation 6】 {In general formula (I), X １ is a tetravalent aliphatic group or aromatic group, Y １ is a divalent aliphatic group or aromatic group, R １ and R ２ are each independently a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkylsilyl group having 3 to 9 carbon atoms, provided that X １ For amounts of 50 mol% or more, see formula (21) below: 【Transformation 7】 The base is represented by the following formulas (22), (23), (24), (25), and (26): 【Transformation 8】 It includes one or more groups selected from the group consisting of groups represented by Y １ For amounts greater than 0 mol% and less than 30 mol%, use formula (1-1): 【Chemistry 9】 The structure is represented by equation (1-1), where A is in equation (A): 【Chemistry 10】 The structure is represented by the formula (31) or (32), where n is 1, m is an integer from 0 to 4, and B is one selected from the group consisting of C1-C6 alkyl groups, C1-C6 alkoxy groups, halogen groups, and C1-C6 fluoroalkyl groups. At least 50 mol% of Y1 is selected from groups represented by the following formulas (31) or (32), except in the case of the group represented by formula (31), which further includes at least one group selected from the group consisting of groups represented by (33), (34), and (35). 【Chemistry 11】 ｝

3. The polyimide precursor composition according to claim 2, wherein A represents a 1,4-phenylene group.

4. A polyimide film for flexible wiring substrates obtained from the polyimide precursor composition according to any one of claims 1 to 3.

5. A polyimide metal laminate comprising a polyimide film according to claim 4 and a metal foil or metal layer laminated together.

6. A flexible wiring substrate in which a metal foil or metal layer of the polyimide metal laminate according to claim 5 is patterned to form wiring.

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