JP7429519B2 - multilayer polyimide film - Google Patents

Description

Polyimide films have excellent mechanical strength, heat resistance, electrical insulation, and chemical resistance, and are therefore widely used as materials for electronic substrates. For example, flexible copper clad laminates (hereinafter also referred to as FCCL), which use polyimide film as a substrate material and have copper foil laminated on at least one side, and flexible printed circuit boards (hereinafter also referred to as FPC), in which circuits are further created, are manufactured. , used in various electronic devices.

BACKGROUND ART In recent years, with the increase in the frequency of electrical signals transmitted through circuits associated with high-speed signal transmission in electronic devices, there is an increasing demand for low dielectric constant and low dielectric loss tangent of polyimide, which is a substrate material. The trend toward higher frequencies is progressing, and it is thought that materials with low dielectric constants and dielectric loss tangents will be required in the future, for example, in the range of 5 GHz or higher, or even 10 GHz or higher. Furthermore, the propagation speed of signals in electronic circuits decreases as the dielectric constant of the substrate material increases. Furthermore, as the dielectric constant and dielectric loss tangent increase, signal transmission loss also increases. Therefore, it is important for the performance of electronic devices to have a low dielectric constant and a low dielectric loss tangent of polyimide as a substrate material, and also to have a small transmission loss when used as an FPC.

An insulating resin layer made of polyimide resin mixed with resin powder having a low dielectric constant is well known as a film used in circuit boards that can be adapted to high frequencies. For example, Patent Document 1 discloses a multilayer polyimide film as a substrate material in which polyimide contains polytetrafluoroethylene (PTFE) powder.

In addition, the dielectric constant and dielectric loss tangent tend to increase as the water absorption rate of the resin increases, so films using resins with high water absorption rates such as polyimide resins are unsuitable as films for high-frequency compatible circuit boards. In Patent Document 2, it is proposed to provide a resin substrate with high transmission speed and low transmission loss by using a resin that does not contain highly water-absorbing functional groups such as amide groups and imide groups. .

Japanese Patent Application Publication No. 2002-144476 JP2012-221968A

However, when blending a fluororesin into a polyimide resin, it may be difficult to uniformly disperse the fluororesin, and there is a problem that the properties tend to vary depending on the location of the film.

In order to lower the water absorption rate of polyimide film with the aim of reducing the dielectric constant and dielectric loss tangent, the concentration of imide groups in the polyimide polymer must be lowered, and as a result, in order to use polyimide film for FPC. There is a problem in that properties that are necessary basic properties are impaired. Specifically, problems arise in that the coefficient of linear expansion increases and the transparency of the film is impaired.

Therefore, an object of the present invention is to provide a polyimide film that can be used for high-frequency circuit boards, which has a low water absorption rate and dielectric loss tangent, and can uniformly express these characteristics without impairing the basic characteristics required for FPCs. The goal is to provide the following.

The present invention can solve the above problems with the following novel multilayer polyimide film having a thermoplastic polyimide resin layer on at least one side of the non-thermoplastic polyimide resin layer.

1). A multilayer polyimide film having a thermoplastic polyimide resin layer on at least one side of a non-thermoplastic polyimide resin layer,
The non-thermoplastic polyimide resin layer is a reaction product of an acid dianhydride and a diamine, and contains 30 mol% or more of the repeating unit of general formula (1) in the acid dianhydride, and/or the diamine contains 30 mol% or more of the repeating unit of general formula (2),
A multilayer polyimide film having a water absorption rate of 1.2% or less and a dielectric loss tangent of 0.005 or less. (However, in general formulas (1) and (2), X is a divalent organic group selected from general formula (3), and in general formula (2), Y is an ester group.General formula (2) and (3), R ¹ is H, a methyl group, an ethyl group, a trifluoromethyl group, and n is an integer from 1 to 4.)

2). The non-thermoplastic polyimide film includes, as the diamine, an aliphatic diamine having 36 carbon atoms, 1,3-bis(4-aminophenoxy)benzene, 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4 The multilayer polyimide film according to 1), which contains at least one diamine selected from '-diaminodiphenyl ether and 2,2-bis(4-aminophenoxyphenyl)propane.

3). Any of 1) or 2), wherein the non-thermoplastic polyimide film contains an acid dianhydride selected from pyromellitic dianhydride and biphenyltetracarboxylic dianhydride as the acid dianhydride. A multilayer polyimide film described in Crab.

The multilayer polyimide film of the present invention has low water absorption and dielectric loss tangent, and has excellent basic characteristics required for FPCs, and can also be used for high-frequency circuit boards.

Embodiments of the present invention will be described below, but the present invention is not limited thereto. Note that all of the academic literature and patent literature described in this specification are incorporated by reference in this specification. In this specification, unless otherwise specified, the numerical range "A to B" means "A or more (including A and larger than A) and B or less (including B and smaller than B)".

The multilayer polyimide film of the present invention is a multilayer polyimide film having a thermoplastic polyimide resin layer on at least one side of a non-thermoplastic polyimide resin layer,
The non-thermoplastic polyimide resin layer is a reaction product of an acid dianhydride and a diamine, and contains 30 mol% or more of the repeating unit of general formula (1) in the acid dianhydride, and/or the diamine contains 30 mol% or more of the repeating unit of general formula (2),
This is a multilayer polyimide film characterized by a water absorption rate of 1.2% or less and a dielectric loss tangent of 0.005 or less. (However, in general formulas (1) and (2), X is a divalent organic group selected from general formula (3), and in general formula (2), Y is an ester group.General formula (2) and (3), R ¹ is H, a methyl group, an ethyl group, a trifluoromethyl group, and n is an integer from 1 to 4.)

(Non-thermoplastic polyimide resin layer)
In the present invention, by using a specific monomer, it is possible to manufacture a non-thermoplastic polyimide resin layer that has a low dielectric constant and a low dielectric loss tangent, and can be used as a circuit board with high transmission speed and high transmission loss.

An example of the method for manufacturing the non-thermoplastic polyimide resin layer of the present invention will be described in detail. Polyamic acid (hereinafter also referred to as polyamic acid), which is a precursor of polyimide used in the present invention, contains at least one diamine and at least one acid dianhydride in an organic solvent such that the moles thereof are substantially equimolar. It is obtained by mixing and reacting with.

前記一般式（１）の酸二無水物を３０モル％以上含むかまたは、前記ジアミン中、一般式（２）の繰り返し単位を、３０モル％以上含むことで、低吸水性かつ低誘電正接のポリイミドを提供することができる。 Further, the non-thermoplastic polyimide resin layer of the present invention contains 30 mol% or more of repeating units of general formula (1) in the acid dianhydride, and/or repeating units of general formula (2) in the diamine. Contains 30 mol% or more of units. (However, in general formulas (1) and (2), X is a divalent organic group selected from general formula (3), and in general formula (2), Y is an ester group.General formula (2) and (3), R ¹ is H, a methyl group, an ethyl group, a trifluoromethyl group, and n is an integer from 1 to 4.)

By containing 30 mol% or more of the acid dianhydride of the general formula (1) or 30 mol% or more of the repeating unit of the general formula (2) in the diamine, the diamine has low water absorption and low dielectric loss tangent. Polyimide can be provided.

Acid dianhydrides that can be used other than general formula (1) are not particularly limited, but specifically, pyromellitic dianhydride, 2,3,6,7-naphthalenetetracarboxylic Acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4' -Benzophenonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propanoic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,4'-oxyphthalic dianhydride , 2,2-bis(3,4-dicarboxyphenyl)propanoic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)propanoic dianhydride Anhydride, 1,1-bis(2,3-dicarboxyphenyl)ethanoic dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethanoic dianhydride, bis(2,3-dicarboxyphenyl)ethanoic dianhydride, carboxyphenyl)methanoic dianhydride, bis(3,4-dicarboxyphenyl)ethanoic dianhydride, oxydiphthalic dianhydride, bis(3,4-dicarboxyphenyl)sulfonic dianhydride, ethylene bis( (trimellitic acid monoester acid anhydride), bisphenol A bis (trimellitic acid monoester acid anhydride), and their analogs. Among these, it is preferable to use pyromellitic dianhydride and 3,3',4,4'-biphenyltetracarboxylic dianhydride.

The acid dianhydride that can be used other than general formula (1) is preferably 0 mol% to 100 mol%, and 30 mol% to 100 mol% when using the diamine of general formula (2). It is more preferable that the amount is 50 mol% to 100 mol%.

The acid dianhydride that can be used other than general formula (1) is preferably 0 mol% to 70 mol%, and 0 mol% to 50 mol% when the diamine of general formula (2) is not used. %, and even more preferably 0 mol% to 30 mol%.

The ester group represented by Y in the general formula (2) is preferably a bond represented by the general formula (4) from the viewpoint of ease of synthesis.

Diamines that can be used other than general formula (2) are not particularly limited, but include aliphatic diamines having 36 carbon atoms, 2,2-bis{4-(4-aminophenoxy)phenyl}propane, , 3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, paraphenylenediamine, 4,4'-diaminodiphenylpropane, 4,4'-bis(4-aminophenoxy) biphenyl, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2-bis(4-aminophenoxyphenyl)propane, 3, 3'-dihydroxy-4,4'-diamino-1,1'-biphenyl, 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diamino-3,3'-dimethylbiphenyl, 4 , 4'-diamino-3,3'-hydroxybiphenyl, 1,4-diaminobenzene, 1,3-diaminobenzene, 4,4'-bis(4-aminophenoxy), 4,4'-diaminodiphenyl ether, 2 ,2-bis{4-(4-aminophenoxy)phenyl}propane, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(3 -aminophenoxy)benzene, etc.

Among the above diamines, aliphatic diamines having 36 carbon atoms, 1,3-bis(4-aminophenoxy)benzene, 4,4'-diamino-2,2'-dimethylbiphenyl, 4,4'-diaminodiphenyl ether, It is preferable that at least one diamine selected from 2,2-bis(4-aminophenoxyphenyl)propane is included.

When using the acid dianhydride of general formula (1), the diamine that can be used other than general formula (2) is preferably 0 mol% to 100 mol%, and 30 mol% to 100 mol%. It is more preferable that the amount is 50 mol% to 100 mol%.

The diamine that can be used other than general formula (2) is preferably 0 mol% to 70 mol%, and 0 mol% to 50 mol% when the acid dianhydride of general formula (1) is not used. %, and even more preferably 0 mol% to 30 mol%.

An aliphatic diamine having 36 carbon atoms is a diamine in which the two terminal carboxylic acid groups (-COOH) of a dimer acid are substituted with a primary aminomethyl group (-CH2-NH2) or an amino group (-NH2). means.
Dimer acid is a known dibasic acid obtained by intermolecular polymerization reaction of unsaturated fatty acids, and its industrial manufacturing process is almost standardized in the industry. It can be obtained by dimerization using etc. Industrially obtained dimer acids are mainly composed of dibasic acids with 36 carbon atoms obtained by dimerizing unsaturated fatty acids with 18 carbon atoms such as oleic acid and linoleic acid, but depending on the degree of purification, , any amount of monomer acid (18 carbon atoms), trimer acid (54 carbon atoms), and other polymerized fatty acids having 20 to 54 carbon atoms. In this embodiment, it is preferable to use a dimer acid whose content of dimer acid has been increased to 90% by mass or more by molecular distillation. Furthermore, although double bonds remain after the dimerization reaction, in this embodiment, dimer acids also include those whose unsaturation level has been reduced by further hydrogenation reaction.

As a feature of the dimer acid type diamine, it is possible to impart properties derived from the skeleton of the dimer acid. That is, since the dimer acid type diamine is a large aliphatic molecule with a molecular weight of approximately 560 to 620, it is possible to increase the molar volume of the molecule and relatively reduce the number of polar groups in polyimide. It is thought that such characteristics of the dimer acid type diamine contribute to improving the dielectric properties while suppressing a decrease in the heat resistance of polyimide. In addition, since it has two freely movable hydrophobic chains with 7 to 9 carbon atoms and two chain-like aliphatic amino groups with a length close to 18 carbon atoms, it not only gives polyimide flexibility, but also Since polyimide can be made to have an asymmetrical chemical structure or a non-planar chemical structure, it is thought that it is possible to lower the dielectric constant of polyimide.
Dimer acid type diamines are commercially available, such as PRIAMINE 1073 (product name) and PRIAMINE 1074 (product name) manufactured by Croda Japan, Versamine 551 (product name) and Versamine 552 (product name) manufactured by Cognis Japan. name) etc.

Among diamines other than general formula (2), the content of aliphatic diamines having 36 carbon atoms is preferably 5 to 15 mol%, more preferably 5 to 10 mol%, based on 100 mol% of the total diamine components.

Polyamic acid, which is a precursor of non-thermoplastic polyimide, can be obtained by mixing the diamine and acid dianhydride in an organic solvent so that the diamine and acid dianhydride have substantially equimolar amounts and reacting them. Any organic solvent can be used as long as it dissolves polyamic acid, but amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, etc. are preferred, and N,N-dimethylformamide and N,N-dimethylacetamide are particularly preferably used. The solid concentration of the polyamic acid is not particularly limited, and as long as it is within the range of 5% by weight to 35% by weight, a polyamic acid having sufficient mechanical strength when made into polyimide can be obtained.

There are no particular limitations on the order in which the diamine and acid dianhydride are added as raw materials, but it is possible to control the properties of the resulting polyimide by controlling not only the chemical structure of the raw materials but also the order of addition.

Fillers can also be added to the polyamic acid for the purpose of improving various properties of the film such as sliding properties, thermal conductivity, electrical conductivity, corona resistance, and loop stiffness. Any filler may be used, but preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and mica.

Additionally, thermosetting resins such as epoxy resins and phenoxy resins, and thermoplastic resins such as polyetherketone and polyetheretherketone may be mixed as long as the properties of the resulting non-thermoplastic polyimide resin layer as a whole are not impaired. good. Examples of the method for adding these resins include adding them to the polyamic acid as long as they are soluble in a solvent. If the polyimide is also soluble, it may be added to the polyimide solution. If it is insoluble in a solvent, a method may be mentioned in which the polyamic acid is first imidized and then composited by melt-kneading. However, it is desirable to use a soluble resin as the resin to be mixed with the polyimide.

(Method for manufacturing non-thermoplastic polyimide resin layer)
To obtain the non-thermoplastic polyimide resin layer of the present invention, the following steps are required: i) Reacting an aromatic diamine and an aromatic tetracarboxylic dianhydride in an organic solvent to obtain a polyamic acid solution;
ii) a step of casting a membrane-forming dope containing the polyamic acid solution onto a support;
iii) peeling off the gel film from the support after heating on the support;
iv) further heating to imidize the remaining amic acid and dry it;
It is preferable to include.

ii) The subsequent steps are broadly classified into thermal imidization methods and chemical imidization methods. The thermal imidization method is a method in which a polyamic acid solution is used as a membrane-forming dope and is dripped onto a support, and imidization is proceeded only by heating, without using a dehydrating ring-closing agent or the like. One of the chemical imidization methods is a method in which a polyamic acid solution containing at least one of a dehydration ring-closing agent and a catalyst as an imidization promoter is used as a film-forming dope to promote imidization. Although either the thermal imidization method or the chemical imidization method may be used, the chemical imidization method is superior in productivity.

As the dehydration ring-closing agent, acid anhydrides typified by acetic anhydride can be suitably used. As the catalyst, tertiary amines such as aliphatic tertiary amines, aromatic tertiary amines, and heterocyclic tertiary amines can be suitably used.

In the following steps (iii), a glass plate, aluminum foil, an endless stainless steel belt, a stainless steel drum, etc. can be suitably used as the support for casting the membrane-forming dope. The heating conditions are set according to the final film thickness and production speed, and after partially imidizing and/or drying, the polyamic acid film (hereinafter referred to as gel film) is peeled off from the support. , or gel membrane).

iv) In the subsequent steps, the edges of the gel film are fixed to avoid shrinkage during curing, dried, water, residual solvent, and imidization accelerator remaining in the film are removed, and the remaining amic Complete imidization of the acid yields a polyimide-containing film. It is preferable that the ends of the gel film are not only fixed, but also stretched in the transport direction or in a direction perpendicular to the transport direction.

The polyimide film obtained in this manner has a small dielectric constant and dielectric loss tangent, so it can be suitably used as a high frequency compatible circuit board.

(Multilayer polyimide film)
In the present invention, a multilayer polyimide film having two or more polyimide resin layers including at least one non-thermoplastic polyimide resin layer described above as a core film and another polyimide resin layer may be used. It is preferable to further include a polyimide resin layer.

(Thermoplastic polyimide film)
The diamine and acid dianhydride used in the thermoplastic polyimide film are the same as those used in the non-thermoplastic polyimide resin layer, but in order to make the thermoplastic polyimide film, diamines with flexibility are used. It is preferable to react the acid dianhydride with the acid dianhydride.

Examples of diamines having flexibility include 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 2,2-bis(4-aminophenoxyphenyl) ) Examples include propane. Examples of acid dianhydrides that can be suitably combined with these diamines include pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4, Examples include 4'-biphenyltetracarboxylic dianhydride and 4,4'-oxydiphthalic dianhydride.

(Method for manufacturing multilayer polyimide film)
In the method for producing a multilayer polyimide film in the present invention, a coextrusion die having a plurality of channels may be used in step ii) to simultaneously form multiple resin layers, or i) to iv described above. ) After the polyimide resin layer has been recovered once, a new resin layer may be formed thereon by coating. For example, in order to obtain a multilayer polyimide film having a thermoplastic polyimide film on at least one side of the above-mentioned core polyimide film, a core polyimide precursor and a thermoplastic polyimide precursor are co-extruded using a die. It can be obtained by casting on a support and performing the subsequent steps of iii).

Since imidization requires a very high temperature, when a resin layer other than polyimide is provided, it is preferable to use the latter method in order to suppress thermal decomposition. In addition, when providing a thermoplastic polyimide film by coating, a precursor of thermoplastic polyimide may be applied and then imidization may be performed, or a thermoplastic polyimide solution may be applied and dried.

Furthermore, the thermoplastic polyimide film may be obtained by casting the polyimide solution and cooling it instead of casting the polyamic acid solution onto the support in the above-mentioned process.

The multilayer polyimide film of the present invention is characterized in that it has a thickness of 25 μm or more. If the thickness of the multilayer polyimide film is less than 25 μm, transmission loss will increase, making it unsuitable for use in high-frequency circuit boards. On the other hand, from the viewpoint of reducing transmission loss, there is no particular upper limit to the thickness of the multilayer polyimide film, but in consideration of ease of manufacturing the multilayer polyimide film, productivity, etc., it is preferably 50 μm or less.

(Flexible metal foil laminate)
The multilayer polyimide film thus obtained can be made into a flexible metal foil laminate by providing metal foil on at least one side of the multilayer polyimide film. As a means of forming metal foil on a multilayer polyimide film,
a) means for obtaining a flexible metal foil laminate by laminating metal foils by heating and pressing after obtaining a multilayer polyimide film as described above;
b) means for obtaining a flexible metal foil laminate by casting an organic solvent solution containing polyamic acid on the metal foil, removing the solvent by heating, and imidizing it;
c) A means for obtaining a flexible metal foil laminate by casting a melt containing a non-thermoplastic polyimide onto a metal foil and cooling it.
Among these, if the non-thermoplastic polyimide is imparted with meltability, the soldering heat resistance and heat shrinkage rate of the resulting flexible metal foil laminate may deteriorate, so methods a) or b) are used. It is preferable. If the non-thermoplastic polyimide is solvent-soluble, an organic solvent solution containing the non-thermoplastic polyimide may be used instead of an organic solvent solution containing the polyamic acid. Details of a) and b) will be explained below.

In the method a), the flexible metal foil laminate of the present invention is obtained by laminating a metal foil to the obtained multilayer polyimide film by heating and pressing (laminate). Regarding the means and conditions for bonding the metal foils, conventionally known methods may be appropriately selected.

In the method b), the means for casting the organic solvent solution containing polyamic acid onto the metal foil is not particularly limited, and conventionally known means such as a die coater, comma coater (registered trademark), reverse coater, knife coater, etc. can be used. Conventionally known means can be used as a heating means for removing the solvent and performing imidization, such as a hot air oven and a far-infrared oven.

Similar to the method a), the chemical imidization method can shorten the heating time and improve productivity. However, since acid is generated from the acid anhydride, which is a dehydration ring-closing agent, during the imidization process, oxidation may progress depending on the type of metal foil. The addition of the dehydrating ring-closing agent is preferably selected appropriately depending on the type of metal foil and heating conditions.

When providing multiple layers of other polyimide or resin layers other than polyimide on a non-thermoplastic polyimide film, repeat the above casting and heating steps multiple times, or create multiple cast layers by coextrusion or continuous casting. A method of forming and heating at the same time can be suitably used.

By means b), the flexible metal foil laminate of the present invention can be obtained at the same time as imidization is completed. When providing metal foil layers on both sides of the resin layer, the metal foils may be bonded to the opposite resin layer surface by heating and pressing.

(metal foil)
The metal foil that can be used in the present invention is not particularly limited, but when using the flexible metal-clad laminate of the present invention for electronic equipment/electrical equipment, for example, copper or copper alloy, stainless steel Or an alloy thereof, a foil made of nickel or a nickel alloy (including 42 alloy), aluminum or an aluminum alloy. In general flexible laminates, copper foils such as rolled copper foils and electrolytic copper foils are often used, but they can also be preferably used in the present invention. Note that the surface of these metal foils may be coated with a rust-proofing layer, a heat-resistant layer, or an adhesive layer. Further, the thickness of the metal foil is not particularly limited, and may be any thickness that can exhibit sufficient functionality depending on the intended use.

(Flexible printed circuit board)
The flexible printed circuit board obtained by etching the metal layer of the flexible metal-clad laminate according to the present invention becomes a high-frequency circuit board with high transmission speed and low transmission loss.

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited only to these Examples.
The methods for evaluating the dielectric constant, dielectric loss tangent, water absorption, and film thickness of the polyimide films in the Synthesis Examples, Examples, and Comparative Examples are as follows.

(Measurement of dielectric constant and dielectric loss tangent)
The dielectric constant and dielectric loss tangent of the polyimide film were measured under the following conditions using a cavity resonator perturbation method complex dielectric constant evaluation device (manufactured by Kanto Denshi Applied Development Co., Ltd.) as a measuring device.
Measurement frequency: 10GHz
Measurement conditions: temperature 22°C to 24°C, humidity 45% to 55%
Measurement sample: A sample left for 24 hours under the above measurement conditions was used.

(Measurement of water absorption rate)
A polyimide film that had been dried at 50°C for 30 minutes was immersed in water at 22 to 24°C for 24 hours, then the moisture on the film surface was wiped off, and the water absorption rate (%) was calculated from the increase in mass before and after immersion in water.

(Measurement of film thickness)
The thickness of the film was measured using a contact thickness meter LASER HOLOGAGE manufactured by Mitsutoyo.

Abbreviations used in Examples and Comparative Examples indicate the following compounds.
ODA: 4,4'-diaminodiphenyl ether m-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl BAPP: 2,2-bis(4-aminophenoxyphenyl)propane TPE-R: 1,3- Bis(4-aminophenoxy)benzene BAPT: Bis(4-aminophenyl) terephthalate PDA: Paraphenylenediamine DDA: Dimer acid type diamine (manufactured by Croda Japan Co., Ltd., trade name: PRIAMINE1074, number of carbon atoms: 36, amine value: 205mgKOH /g, content of dimer component; 95% by weight or more)
PMDA: Pyromellitic dianhydride BPDA: 3,3',4,4'-biphenyltetracarboxylic dianhydride TMHQ: Paraphenylene bis(trimellitate anhydride)
DMF: N,N-dimethylformamide DMAc: N,N-dimethylacetamide

(Synthesis of non-thermoplastic polyimide precursor (polyamic acid))
(Synthesis example 1)
At room temperature and under a nitrogen atmosphere, 330.39 g of DMF, 13.30 g of TPE-R, and 7.25 g of m-TB were added to a 2000 ml separable flask, and while stirring, 15.66 g of TMHQ and 8.20 g of PMDA were gradually added. After visually confirming that the solution had been dissolved, stirring was performed for 30 minutes. Thereafter, 3.69 g of PDA was added, and then 8.45 g of PMDA was gradually added while stirring, and after confirming that the PMDA had dissolved, the mixture was stirred for 30 minutes. Finally, a solution of 0.75 g of PMDA dissolved in DMF to a solid content concentration of 7.2% was prepared, and this solution was gradually added to the above reaction solution while being careful not to increase the viscosity. When the viscosity at °C reached 2000 poise, addition and stirring were stopped to obtain a polyimide precursor.

(Synthesis example 2)
At room temperature and under a nitrogen atmosphere, 331.20 g of DMF, 6.10 g of TPE-R, 6.65 g of m-TB, and 8.57 g of BAPP were added to a 2000 ml separable flask, and 19.35 g of BPDA was gradually added while stirring. After visually confirming that the solution had been dissolved, stirring was performed for 30 minutes. Thereafter, 10.91 g of BAPT was added, and then 7.74 g of PMDA was gradually added while stirring, and after confirming that PMDA had dissolved, the mixture was stirred for 30 minutes. Finally, a solution of 0.68 g of PMDA dissolved in DMF to a solid concentration of 7.2% was prepared, and this solution was gradually added to the above reaction solution while being careful not to increase the viscosity. When the viscosity at °C reached 2000 poise, addition and stirring were stopped to obtain a polyimide precursor.

(Synthesis example 3)
At room temperature and under a nitrogen atmosphere, add 340.00 g of DMF, 11.96 g of ODA, and 8.92 g of BAPT to a 2000 ml separable flask, and gradually add 37.94 g of TMHQ while stirring, and visually confirm that it has dissolved. , stirring was performed for 30 minutes. Finally, 1.17 g of TMHQ was gradually added to the above reaction solution while being careful not to increase the viscosity, and when the viscosity at 23°C reached 2000 poise, the addition and stirring were stopped to obtain a polyimide precursor. Ta.

(Synthesis example 4)
At room temperature and under a nitrogen atmosphere, 340.00 g of DMAc, 9.79 g of ODA, 8.52 g of BAPT, and 4.34 g of DDA were added to a 2000 ml separable flask, and while stirring, 36.23 g of TMHQ was gradually added and dissolved. After visually confirming this, stirring was performed for 30 minutes. Finally, 1.12 g of TMHQ was gradually added to the above reaction solution while being careful not to increase the viscosity, and when the viscosity at 23°C reached 2000 poise, the addition and stirring were stopped to obtain a polyimide precursor. Ta.

(Synthesis example 5)
At room temperature and under a nitrogen atmosphere, 340.00 g of DMF and 24.30 g of ODA were added to a 2000 ml separable flask, and 34.63 g of TMHQ was gradually added while stirring. After visually confirming that TMHQ had dissolved, stirring was continued for 30 minutes. Finally, 1.25 g of TMHQ was gradually added to the above reaction solution while being careful not to increase the viscosity, and when the viscosity at 23°C reached 2000 poise, the addition and stirring were stopped to obtain a polyimide precursor. Ta.

(Synthesis example 6)
At room temperature and under a nitrogen atmosphere, 340.00 g of DMF and 32.53 g of BAPT were added to a 2000 ml separable flask, and 26.65 g of BPDA was gradually added while stirring. After visually confirming that BPDA had dissolved, stirring was continued for 30 minutes. Finally, 0.82 g of BPDA was gradually added to the above reaction solution while being careful not to increase the viscosity, and when the viscosity at 23°C reached 2000 poise, the addition and stirring were stopped to obtain a polyimide precursor. Ta.

(Synthesis example 7)
At room temperature and under a nitrogen atmosphere, 327.90 g of DMF and 28.72 g of ODA were added to a 2000 ml separable flask, and while stirring, 30.34 g of PMDA was gradually added. After visually confirming that PMDA had dissolved, stirring was continued for 30 minutes. Finally, a solution of 0.94 g of PMDA dissolved in DMF to a solid concentration of 7.2% was prepared, and this solution was gradually added to the above reaction solution while being careful not to increase the viscosity. When the viscosity at °C reached 2000 poise, addition and stirring were stopped to obtain a polyimide precursor.

(Synthesis example 8)
At room temperature and under a nitrogen atmosphere, 340.00 g of DMF and 24.30 g of ODA were added to a 2000 ml separable flask, and 34.63 g of BPDA was gradually added while stirring. After visually confirming that BPDA had dissolved, stirring was continued for 30 minutes. Finally, 1.07 g of BPDA was gradually added to the above reaction solution while being careful not to increase the viscosity, and when the viscosity at 23°C reached 2000 poise, the addition and stirring were stopped to obtain a polyimide precursor. Ta.

(Synthesis example 9)
At room temperature and under a nitrogen atmosphere, 329.40 g of DMF, 7.34 g of TPE-R, 8.00 g of m-TB, and 10.31 g of BAPP were added to a 2000 ml separable flask, and 11.09 g of BPDA and 9.04 g of PMDA were gradually added while stirring. After visually confirming that the solution had been dissolved, stirring was performed for 30 minutes. Then, after adding 4.08 g of PDA, 9.32 g of PMDA was gradually added while stirring, and after confirming that the PMDA had dissolved, the mixture was stirred for 30 minutes. Finally, a solution of 0.82 g of PMDA dissolved in DMF to a solid content concentration of 7.2% was prepared, and this solution was gradually added to the above reaction solution while being careful not to increase the viscosity. When the viscosity at °C reached 2000 poise, addition and stirring were stopped to obtain a polyimide precursor.

(Synthesis of thermoplastic polyimide precursor (polyamic acid))
(Synthesis example 10)
At room temperature and under a nitrogen atmosphere, add 323.04 g of DMF and 43.61 g of BAPP to a 2000 ml separable flask, and gradually add 4.69 g of BPDA and 19.00 g of PMDA while stirring, visually confirming that they have dissolved. After that, stirring was performed for 30 minutes. Finally, a solution of 0.70 g of PMDA dissolved in DMF to a solid content concentration of 7.2% was prepared, and this solution was gradually added to the above reaction solution while being careful not to increase the viscosity. When the viscosity at °C reached 1000 poise, addition and stirring were stopped to obtain a polyimide precursor.

(Synthesis example 11)
At room temperature and under a nitrogen atmosphere, 299.82 g of DMF and 32.18 g of TPE-R were added to a 2000 ml separable flask, and while stirring, 34.13 g of BPDA was gradually added, and after visually confirming that it had dissolved, Stirring was performed for 30 minutes. Finally, a solution of 1.69 g of BAPP dissolved in DMF to a solid content concentration of 5.0% was prepared, and this solution was gradually added to the above reaction solution while being careful not to increase the viscosity. When the viscosity at °C reached 1000 poise, addition and stirring were stopped to obtain a polyimide precursor.

(Example 1)
To the non-thermoplastic polyimide precursor (60 g) obtained in Synthesis Example 1, 30.0 g of a curing agent consisting of acetic anhydride/isoquinoline/DMF (weight ratio 2.48/0.75/4.27) was added. The mixture was stirred and degassed at a temperature of 0° C. or lower, and cast onto aluminum foil using a comma coater. After heating this resin film at 110°C for 130 seconds, the self-supporting gel film was peeled off from the aluminum foil, fixed on a metal fixing frame, and dried at 250°C for 15 seconds and 350°C for 79 seconds. It was imidized to obtain a polyimide film with a thickness of 17 μm. Table 1 shows the dielectric constant, dielectric loss tangent, and water absorption rate of the obtained polyimide film.
After diluting the thermoplastic polyimide precursor obtained in Synthesis Example 10 to a solid content concentration of 10% by weight, it was cast on one side of the polyimide film obtained above using a comma coater so that the final thickness on one side was 4 μm. It was coated and dried at 120°C for 120 seconds. The other side was similarly coated with a thermoplastic polyimide precursor to a final thickness of 4 μm, and then dried at 120° C. for 120 seconds. Subsequently, heat treatment was performed at 350° C. for 20 seconds to obtain a polyimide laminate having a total thickness of 25 μm. Table 2 shows the dielectric constant and dielectric loss tangent of the obtained polyimide laminate.

(Example 2 to Example 6)
Synthesis Examples 2 to 4 were carried out in the same manner as in Example 1, except that the non-thermoplastic polyimide precursor obtained in Synthesis Example 1 was changed to Synthesis Examples 2 to 4. Table 1 shows the dielectric constant, dielectric loss tangent, and water absorption rate of the obtained polyimide film. Further, Table 2 shows the dielectric constant and dielectric loss tangent of the obtained polyimide laminate.

(Example 7)
The same procedure as in Example 1 was carried out except that the thermoplastic polyimide precursor obtained in Synthesis Example 10 was changed to Synthesis Example 11. Table 1 shows the dielectric constant, dielectric loss tangent, and water absorption rate of the obtained polyimide film. Further, Table 2 shows the dielectric constant and dielectric loss tangent of the obtained polyimide laminate.

(Example 8)
The same procedure as in Example 5 was carried out except that the non-thermoplastic polyimide precursor obtained in Synthesis Example 1 was changed to Synthesis Example 2. Table 1 shows the dielectric constant, dielectric loss tangent, and water absorption rate of the obtained polyimide film. Further, Table 2 shows the dielectric constant and dielectric loss tangent of the obtained polyimide laminate.

(Comparative Examples 1 to 3)
Examples 7 to 9 were carried out in the same manner as in Example 1, except that the non-thermoplastic polyimide precursor obtained in Synthesis Example 1 was changed to Synthesis Examples 7 to 9. Table 1 shows the dielectric constant, dielectric loss tangent, and water absorption rate of the obtained polyimide film. Further, Table 2 shows the dielectric constant and dielectric loss tangent of the obtained polyimide laminate.

Claims (3)

A multilayer polyimide film having thermoplastic polyimide resin layers on both sides of a non-thermoplastic polyimide resin layer,
The non-thermoplastic polyimide resin layer is a reaction product of acid dianhydride and diamine,
The acid dianhydride contains 70 mol% or more and 100 mol% or less of the compound of general formula (1), and the diamine does not contain the compound of general formula (2), or the diamine contains the compound of general formula (1) (2) contains 70 mol% or more and 100 mol% or less , and the acid dianhydride does not contain the compound of general formula (1),
The thermoplastic polyimide resin layer contains 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 1,3-bis(3-aminophenoxy)benzene, 1 , 3-bis(4-aminophenoxy)benzene and at least one diamine selected from 2,2-bis(4-aminophenoxyphenyl)propane, and pyromellitic dianhydride, 3,3',4,4 At least one acid dianhydride selected from '-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 4,4'-oxydiphthalic dianhydride. is a reactant,
A multilayer polyimide film having a water absorption rate of 1.2% or less and a dielectric loss tangent of 0.005 or less.

(In the general formulas (1) and (2 ) , X is a divalent organic group selected from the general formula (3), Y is an ester group, and In general formulas (2) and (3), R ¹ is H , a methyl group, an ethyl group , or a trifluoromethyl group, and n is an integer of 1 to 4.) The diamine forming the non-thermoplastic polyimide resin layer is an aliphatic diamine having 36 carbon atoms, 1,3-bis(4-aminophenoxy)benzene, 4,4'-diamino-2,2'-dimethylbiphenyl, 4 , 4'-diaminodiphenyl ether, and 2,2- bis (4-aminophenoxyphenyl)propane. Claim 1 or 2 , wherein the acid dianhydride forming the non-thermoplastic polyimide resin layer contains at least one selected from pyromellitic dianhydride and biphenyltetracarboxylic dianhydride. The multilayer polyimide film described.