CN116194512A

CN116194512A - Low dielectric polyimide film and method for producing same

Info

Publication number: CN116194512A
Application number: CN202180064230.2A
Authority: CN
Inventors: 赵珉相; 李吉男
Original assignee: Polyimide Advanced Materials Co ltd
Current assignee: Polyimide Advanced Materials Co ltd
Priority date: 2020-09-23
Filing date: 2021-09-16
Publication date: 2023-05-30
Also published as: KR102473354B1; KR20220040278A; WO2022065804A1

Abstract

The present invention relates to a polyimide film produced by imidizing a polyamic acid solution containing an acid dianhydride component including diphenyl tetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA), and a diamine component including m-tolidine (m-tolidine) and p-phenylenediamine (PPD), wherein the m-tolidine is 30 to 50 mol% and the p-phenylenediamine is 50 to 70 mol% based on 100 mol% of the total content of the diamine component, and a method for producing the same.

Description

Low dielectric polyimide film and method for producing same

Technical Field

The present invention relates to a low dielectric polyimide film having improved dielectric characteristics and a method for producing the same.

Background

Polyimide (PI) is a polymer material having the highest level of heat resistance, chemical resistance, electrical insulation, chemical resistance, and weather resistance among organic materials based on an imide ring and a rigid aromatic main chain, which are excellent in chemical stability.

In particular, excellent insulating properties, i.e., excellent electrical properties such as low dielectric constant, are attracting attention as high-functional polymer materials in the fields of electric, electronic, optical, and the like.

In recent years, with the progress of weight reduction and miniaturization of electronic products, thin circuit boards having high integration and flexibility have been actively developed.

Such a thin circuit board tends to be used in many cases in a structure in which a circuit including a metal foil is formed on a polyimide film having excellent heat resistance, low temperature resistance, and insulating properties and being easily bent.

As such a thin circuit board, a flexible metal foil laminate is mainly used, and for example, a flexible copper foil laminate (Flexible Copper Clad Laminate, FCCL) using a thin copper plate as a metal foil is included. In addition, polyimide is also used as a protective film, an insulating film, or the like of a thin circuit board.

On the other hand, in recent years, various functions have been incorporated in electronic devices, and thus the electronic devices are required to have a fast operation speed and a fast communication speed, and in order to meet such a demand, thin circuit boards capable of high-speed communication at high frequencies have been developed.

However, in the case of a general polyimide, it is a practical case that the dielectric characteristics have not yet reached an excellent level sufficient to maintain sufficient insulation in high frequency communication.

Further, it is known that the lower the dielectric characteristics of the insulator, the less unwanted parasitic capacity (stray capacitance) and noise are generated in the thin circuit board, and the problem of communication delay can be solved to a large extent.

Therefore, in practice, polyimide with low dielectric characteristics is considered to be the most important factor affecting the performance of a thin circuit substrate.

In particular, in the case of high-frequency communication, dielectric loss (dielectric dissipation) inevitably occurs through polyimide, and dielectric loss tangent (dielectric dissipation factor; df) is a degree of waste of electric energy of a thin circuit board and is closely related to signal transmission delay determining communication speed, so that keeping the dielectric loss tangent of polyimide as low as possible is also considered as an important factor affecting the performance of the thin circuit board.

In addition, the more moisture the polyimide film contains, the greater the dielectric constant and the greater the dielectric loss tangent. In the case of polyimide films, although they are suitable as materials for thin circuit boards due to excellent inherent properties, they are relatively vulnerable to moisture due to polar imide groups, and thus the insulating properties may be degraded.

Therefore, in practice, it is required to develop a polyimide film which maintains mechanical properties, thermal properties and chemical resistance characteristics peculiar to polyimide at a certain level and has a small dielectric property, particularly a dielectric loss tangent.

Prior art literature

Patent literature

(patent document 1) Korean laid-open patent publication No. 10-2015-0069318

Disclosure of Invention

Technical problem

The present invention provides a polyimide film having high heat resistance, low dielectric properties and low moisture absorption properties, and a method for producing the same.

For this purpose, the invention has for its practical purpose to provide specific embodiments thereof.

Means for solving the problems

In order to achieve the above object, an embodiment of the present invention provides a polyimide film produced by imidizing a polyamic acid solution containing an acid dianhydride component including diphenyl tetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) and a diamine component including m-tolidine (m-tolidine) and p-phenylenediamine (PPD),

the content of m-toluidine is 30 to 50 mol% and the content of p-phenylenediamine is 50 to 70 mol%, based on 100 mol% of the total diamine component.

In one embodiment, the content of the biphenyl tetracarboxylic dianhydride may be 45 mol% or more and 65 mol% or less, and the content of pyromellitic dianhydride (PMDA) may be 35 mol% or more and 55 mol% or less, based on 100 mol% of the total content of the acid dianhydride components.

In one embodiment, the polyimide film may include a block copolymer composed of 2 or more blocks.

For example, a block copolymer may be included which has a first block obtained by imidizing an acid dianhydride component containing biphenyltetracarboxylic acid dianhydride and a diamine component containing m-tolidine (m-tolidine) and p-phenylenediamine, and a second block obtained by imidizing an acid dianhydride component containing biphenyltetracarboxylic acid dianhydride and pyromellitic acid dianhydride and a diamine component containing m-tolidine.

The polyimide film may have a glass transition temperature (Tg) of 300 ℃ or higher and a dielectric loss tangent (Df) of 0.003 or lower.

In addition, the moisture permeability may be 0.02 ((g/(m) ² * Day))/. Mu.m) or less, the coefficient of thermal expansion may be 15 to 18 ppm/. Degree.C.

Another embodiment of the present invention provides a method for producing a polyimide film, including: (a) A step of polymerizing a first acid dianhydride component and a first diamine component in an organic solvent to produce a first polyamic acid;

(b) A step of polymerizing a second acid dianhydride component and a second diamine component in an organic solvent to produce a second polyamic acid;

(c) A step of copolymerizing the first polyamic acid and the second polyamic acid in an organic solvent to produce a third polyamic acid; and

(d) A step of forming a film of the precursor composition containing the third polyamic acid on a support and then imidizing the film,

the first acid dianhydride component and the second acid dianhydride component each contain one or more selected from the group consisting of biphenyl tetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA),

the first diamine component and the second diamine component each contain one or more selected from the group consisting of m-tolidine (m-tolidine) and p-phenylenediamine (PPD),

the m-toluidine is contained in an amount of 30 to 50 mol% and the p-phenylenediamine is contained in an amount of 50 to 70 mol% based on 100 mol% of the total of the first diamine component and the second diamine component.

The present invention also provides a multilayer film comprising the polyimide film and a thermoplastic resin layer.

The present invention also provides a flexible metal foil laminate comprising the polyimide film and a conductive metal foil.

Further, an electronic component including the flexible metal foil laminate is provided.

Effects of the invention

The polyimide film according to the embodiment of the present invention uses a specific acid dianhydride component and a specific diamine component in combination in a specific molar ratio, thereby minimizing the moisture absorption rate and moisture permeability and having low dielectric characteristics and high heat resistance characteristics.

The present invention can realize high-speed communication at a high frequency of 10GHz or more by including the polyimide film described above, and thus can be effectively applied to electronic components such as a flexible metal foil laminate.

Detailed Description

Best mode for carrying out the invention

Hereinafter, embodiments of the present invention will be described in more detail in accordance with the order of "polyimide film" and "method for producing polyimide film" according to the present invention.

Before this, the terms or words used in the present specification and claims should not be interpreted as meaning in general or dictionary, but should be interpreted in accordance with the meaning and concept conforming to the technical idea of the present invention on the basis of the principle that the inventor can properly define the concept of terms to explain the invention in an optimal way.

Therefore, the configuration of the embodiment described in the present specification is only one embodiment which is the most preferable of the present invention, and does not represent all the technical ideas of the present invention, and therefore it should be understood that there may be various equivalents and modifications that can replace these embodiments when the present application is presented.

In this specification, the expression in the singular includes the expression in the plural unless the context clearly indicates otherwise. In this specification, it should be understood that the terms "comprises," "comprising," "includes," or "having," etc., are intended to specify the presence of stated features, integers, steps, components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, components, or groups thereof.

In the present specification, where amounts, concentrations or other values or parameters are given as a list of ranges, preferred ranges or upper values and preferred lower values, it is to be understood that any pair of any upper range limit or preferred value and any lower range limit or preferred value is specifically disclosed whether or not the ranges are individually disclosed.

Where a range of values is recited in the specification, unless otherwise stated, the range is intended to include the endpoints and all integers and fractions within the range. The scope of the invention is not intended to be limited to the particular values recited when defining the range.

In this specification, "acid dianhydride" is intended to include precursors or derivatives thereof which, although they may not be technically acid dianhydrides, still react with diamines to form polyamic acids which can be reconverted to polyimides.

In this specification, "diamine" is intended to include precursors or derivatives thereof which, although they may not be technically diamines, still react with dianhydrides to form polyamic acids which can be reconverted to polyimides.

The polyimide film of the present invention is produced by imidizing a polyamic acid solution containing an acid dianhydride component and a diamine component.

The acid dianhydride component may include one or more selected from the group consisting of diphenyl tetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA).

The diamine component may include one or more selected from the group consisting of m-tolidine (m-tolidine) and p-phenylenediamine (PPD).

For example, the polyimide film of the present invention can be obtained by imidizing a polyamic acid solution containing an acid dianhydride component including biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) and a diamine component including m-tolidine (m-tolidine) and p-phenylenediamine (PPD).

The present invention can realize crystallinity of the film by the above-mentioned biphenyl tetracarboxylic dianhydride (BPDA) and m-tolidine (m-tolidine).

According to an embodiment of the present invention, in the diamine component, the content of m-toluidine may be 0 mol% or more and 50 mol% or less, and the content of p-phenylenediamine may be 50 mol% or more and 70 mol% or less, based on 100 mol% of the total diamine component.

Preferably, the content of m-toluidine may be 30 mol% or more and 50 mol% or less. Such m-toluidine has particularly a hydrophobic methyl group, and thus can contribute to low moisture absorption characteristics of the polyimide film.

In the present invention, when the diamine component contains m-tolidine and p-phenylenediamine in the above-mentioned content ranges, the low dielectric characteristics are exhibited, and the low transmission loss characteristics can be exhibited even at high frequencies.

In the acid dianhydride component, the content of the biphenyl tetracarboxylic dianhydride (BPDA) may be 45 mol% or more and 65 mol% or less, and the content of the pyromellitic dianhydride (PMDA) may be 35 mol% or more and 55 mol% or less, based on 100 mol% of the total content of the acid dianhydride component.

Preferably, the content of the biphenyl tetracarboxylic dianhydride (BPDA) may be 45 mol% or more and 55 mol% or less, and the content of the pyromellitic dianhydride (PMDA) may be 45 mol% or more and 55 mol% or less. When the acid dianhydride component contains biphenyl tetracarboxylic dianhydride and pyromellitic dianhydride (PMDA) in the above-described content ranges, the mechanical properties of the polyimide film can be improved, and the heat resistance at a level suitable for manufacturing a flexible metal foil laminate can be ensured. In addition, there is an advantage in that it is advantageous to ensure a desired level of dielectric loss tangent and moisture permeability.

In the present invention, the polyimide chain derived from biphenyl tetracarboxylic dianhydride has a structure called a charge transfer complex (CTC: charge transfer complex), i.e., a regular linear structure in which an electron donor (electron donnor) and an electron acceptor (electron acceptor) are close to each other, and intermolecular interactions (intermolecular interaction) are enhanced.

Such a structure has an effect of preventing hydrogen bonding with moisture, and thus can exert an influence on reducing the moisture absorption rate, thereby maximizing the effect of reducing the moisture permeability of the polyimide film.

In addition, pyromellitic dianhydride contained as the acid dianhydride component has a relatively rigid structure, and can impart suitable elasticity to the polyimide film, which is preferable from the viewpoint of being preferred.

The content ratio of the acid dianhydride is particularly important in order to satisfy both the proper elasticity and the moisture absorption rate of the polyimide film. For example, the lower the content ratio of biphenyl tetracarboxylic dianhydride, the more difficult it is to expect the low moisture absorption rate due to the CTC structure.

In addition, biphenyl tetracarboxylic dianhydride contains 2 benzene rings corresponding to an aromatic moiety, and pyromellitic dianhydride contains 1 benzene ring corresponding to an aromatic moiety.

In the acid dianhydride component, an increase in the content of pyromellitic dianhydride based on the same molecular weight is understood to be an increase in the number of imide groups in the molecule. This is understood to mean that the ratio of imide groups derived from pyromellitic dianhydride in the polyimide polymer chain is relatively increased as compared with imide groups derived from biphenyl tetracarboxylic dianhydride.

That is, an increase in the content of pyromellitic dianhydride can be considered as a relative increase in the imide groups relative to the whole polyimide film, and therefore it is difficult to expect a low moisture absorption rate.

In contrast, if the content ratio of pyromellitic dianhydride is reduced, the composition of the rigid structure is relatively reduced, and the mechanical properties of the polyimide film may be reduced below a desired level.

For this reason, when the content of the biphenyl tetracarboxylic dianhydride is higher than the above range, the mechanical properties of the polyimide film are lowered, and the heat resistance at a level suitable for manufacturing a flexible metal foil laminate is not ensured.

In contrast, in the case where the content of the above-mentioned biphenyl tetracarboxylic dianhydride is lower than the above-mentioned range or the content of pyromellitic dianhydride is higher than the above-mentioned range, it is difficult to achieve a proper level of dielectric constant, dielectric dissipation factor and moisture absorption, and thus, it is not preferable.

In one embodiment, the polyimide film may contain a block copolymer composed of 2 or more blocks, and may contain 2 blocks, for example.

Each of the 2 blocks may be: a first block obtained by imidizing an acid dianhydride component containing biphenyltetracarboxylic acid dianhydride with a diamine component containing m-tolidine and p-phenylenediamine; and a second block obtained by imidizing an acid dianhydride component containing biphenyl tetracarboxylic dianhydride and pyromellitic dianhydride with a diamine component containing m-toluidine.

Thus, the first block and the second block may be formed by imidization of the respective specific monomers.

The polyimide film of the present invention comprises a first block having film-forming processability and low dielectric characteristics due to heat resistance and a second block having low dielectric characteristics reinforced by crystallinity, thereby being capable of exhibiting desired heat resistance characteristics, low dielectric characteristics and low moisture absorption characteristics.

For example, in forming the above first block, the contents of biphenyl tetracarboxylic dianhydride, m-tolidine (m-tolidine) and p-phenylenediamine may be appropriately adjusted as necessary to ensure high heat resistance and low dielectric characteristics. That is, the polyimide film of the present invention can secure a glass transition temperature (Tg) of 300 ℃ or higher and a dielectric loss tangent (Df) of 0.003 or lower, and thus can exhibit high heat resistance and low dielectric characteristics.

In addition, the above polyimide film can adjust crystallinity by including the second block of biphenyl tetracarboxylic dianhydride and m-tolidine (m-tolidine), thereby minimizing moisture absorption and moisture permeability to achieve improvement of low dielectric characteristics.

Further, the present invention can secure interlayer dimensional stability by appropriately controlling the content of biphenyl tetracarboxylic dianhydride used in forming the above-mentioned second block as needed to have a thermal expansion coefficient of 15 to 18ppm/°c similar to that of copper foil.

As described above, the polyimide film of the present invention may have a glass transition temperature (Tg) of 300 ℃ or higher and a dielectric loss tangent (Df) of 0.003 or less. The moisture permeability may be 0.02 ((g/(m) ² * Day))/. Mu.m) or less, may be 15 to 18 ppm/. Degree.C.for the coefficient of thermal expansion.

In this regard, a polyimide film satisfying the above dielectric loss tangent (Df), glass transition temperature, moisture permeability, and/or thermal expansion coefficient ranges can be used as an insulating film for a flexible metal foil laminate, and not only can insulation stability be ensured, but also signal transmission delay can be minimized even if the manufactured flexible metal foil laminate is used for an electrical signal transmission circuit that transmits signals at a high frequency of 10GHz or more.

The above-mentioned "dielectric loss tangent" refers to a force dissipated by a dielectric body (or insulator) when friction of molecules hinders movement of molecules caused by an alternating electric field.

The value of the dielectric loss tangent is generally used as an index indicating the easiness of charge extinction (dielectric loss), and the higher the dielectric loss tangent is, the more easily the charge is extinguished, whereas the lower the dielectric loss tangent is, the less easily the charge is extinguished. That is, the dielectric loss tangent is a measure of power loss, and as the dielectric loss tangent becomes smaller, signal transmission delay due to power loss can be reduced while maintaining a communication speed fast.

This is a strongly demanded matter of the polyimide film as an insulating film, and the dielectric loss tangent of the polyimide film of the present invention at a very high frequency of 10GHz may be 0.004 or less.

The moisture permeability is a moisture content of a material, and generally, when the moisture permeability is high, it is known that a dielectric constant and a dielectric loss tangent increase.

In general, it is known that water has a dielectric constant of 100 or more in a solid state, about 80 in a liquid state, and 1.0059 in a gaseous state.

For example, in a state where the polyimide film absorbs water vapor or the like, water exists in a liquid state, and at this time, the dielectric constant and dielectric loss tangent of the polyimide film are remarkably improved.

That is, only a small amount of moisture is absorbed, and the dielectric constant and dielectric loss tangent of the polyimide film may also change drastically.

The polyimide film of the present invention may have a moisture permeability of 0.02 ((g/(m) ² * Day))/. Mu.m) or less, which is attributable to the characteristics of the polyimide film of the present invention in terms of constitution.

As will be described in more detail later, this seems to be due to the inclusion of a nonpolar moiety in the molecular structure of the polyimide film of the present invention.

As described above, the polyimide film of the present invention satisfies all of the above conditions, and therefore can be used as an insulating film for a flexible metal foil laminate, and not only can insulation stability be ensured even at high frequencies, but also signal transmission delay can be minimized.

In the present invention, the polyamic acid can be produced by the following method:

(1) A method in which the entire diamine component is added to a solvent, and then an acid dianhydride component is added in a substantially equimolar manner to the diamine component to polymerize the diamine component;

(2) A method in which the entire acid dianhydride component is added to a solvent, and then a diamine component is added in a substantially equimolar manner to the acid dianhydride component to polymerize the acid dianhydride component;

(3) A method in which a part of the diamine component is added to a solvent, and then a part of the acid dianhydride component is mixed at a ratio of about 95 to 105 mol% with respect to the reaction component, and then the remaining diamine component is added, and then the remaining acid dianhydride component is added, whereby the diamine component and the acid dianhydride component are polymerized so as to be substantially equimolar;

(4) A method in which a part of the diamine compound is mixed at a ratio of about 95 to 105 mol% with respect to the reaction component after adding the acid dianhydride component to the solvent, then the other acid dianhydride component is added, and then the remaining diamine component is added, whereby the diamine component and the acid dianhydride component are polymerized so as to be substantially equimolar;

(5) A method in which a part of the diamine component and a part of the acid dianhydride component are reacted in a solvent so as to be in excess of either one to form a first composition, and a part of the diamine component and a part of the acid dianhydride component are reacted in another solvent so as to be in excess of either one to form a second composition, and then the first and second compositions are mixed and polymerized, wherein when the first composition is formed, if the diamine component is in excess, the acid dianhydride component is in excess in the second composition, and if the acid dianhydride component is in excess in the first composition, the diamine component is in excess in the second composition, whereby the first and second compositions are mixed and the whole diamine component used in their reactions is polymerized so as to be in substantially equimolar relation to the acid dianhydride component; etc.

However, the polymerization method is not limited to the above example, and any known method can be used for producing the first to third polyamic acids.

In one specific example, the method for producing a polyimide film of the present invention may comprise:

(a) A step of polymerizing a first acid dianhydride component and a first diamine component in an organic solvent to produce a first polyamic acid;

(d) And a step of forming a film of the precursor composition containing the third polyamic acid on a support and then imidizing the film.

The first acid dianhydride component and the second acid dianhydride component may each include one or more selected from the group consisting of diphenyl tetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA).

The first diamine component and the second diamine component are characterized by containing one or more selected from the group consisting of m-tolidine (m-tolidine) and p-phenylenediamine (PPD).

The m-toluidine may be contained in an amount of 30 to 50 mol% based on 100 mol% of the total content of the first diamine component and the second diamine component, and the p-phenylenediamine may be contained in an amount of 50 to 70 mol%.

The content of the biphenyltetracarboxylic acid dianhydride may be 45 to 65 mol% and the content of the pyromellitic acid dianhydride (PMDA) may be 35 to 55 mol% based on 100 mol% of the total content of the first acid dianhydride component and the second acid dianhydride component.

Preferably, the first polyamic acid may include an acid dianhydride component including biphenyl tetracarboxylic dianhydride and a diamine component including m-tolidine and p-phenylenediamine, and the second polyamic acid may include an acid dianhydride component including biphenyl tetracarboxylic dianhydride and pyromellitic dianhydride and a diamine component including m-tolidine.

In the present invention, the polymerization method of the polyamic acid as described above can be defined by an arbitrary (random) polymerization method, and a polyimide film produced from the polyamic acid of the present invention produced by the process as described above can be preferably used in terms of maximizing the effect of the present invention of reducing the dielectric loss tangent (Df) and the moisture absorption and moisture permeability.

However, the polymerization method described above may have a limitation in that the length of the repeating unit in the polymer chain described above is made short, and thus, the polyimide chain derived from the acid dianhydride component may exhibit various excellent properties. Therefore, the polymerization method of the polyamic acid that can be particularly preferably used in the present invention may be a block polymerization method.

On the other hand, the solvent used for synthesizing the polyamic acid is not particularly limited, and any solvent may be used as long as it is a solvent that dissolves the polyamic acid, and an amide-based solvent is preferable.

Specifically, the solvent may be an organic polar solvent, specifically, an aprotic polar solvent (aprotic polar solvent), and for example, may be one or more selected from the group consisting of N, N-Dimethylformamide (DMF), N-dimethylacetamide, N-methyl-pyrrolidone (NMP), γ -butyrolactone (GBL), and Diglyme (Diglyme), but is not limited thereto, and may be used alone or in combination of two or more as needed.

In one example, the above solvent may particularly preferably be N, N-dimethylformamide and N, N-dimethylacetamide.

In addition, fillers may be added in the polyamic acid production process to improve various properties of the film such as slidability, thermal conductivity, corona resistance, loop hardness (loop hardness), and the like. The filler to be added is not particularly limited, and preferable examples thereof include silica, titanium oxide, aluminum oxide, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, and the like.

The particle diameter of the filler is not particularly limited as long as it is determined according to the film characteristics to be modified and the kind of filler added. In general, the average particle diameter is from 0.05 to 100. Mu.m, preferably from 0.1 to 75. Mu.m, more preferably from 0.1 to 50. Mu.m, particularly preferably from 0.1 to 25. Mu.m.

If the particle diameter is less than the above range, the modifying effect is not easily exhibited, and if it is more than the above range, the surface properties may be greatly impaired or the mechanical properties may be greatly lowered.

The amount of filler to be added is not particularly limited, and may be determined depending on the film properties to be modified, the particle size of the filler, and the like. In general, the filler is added in an amount of 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, more preferably 0.02 to 80 parts by weight, relative to 100 parts by weight of the polyimide.

If the amount of the filler is less than the above range, the modifying effect by the filler is not easily exhibited, and if it exceeds the above range, the mechanical properties of the film may be greatly impaired. The method of adding the filler is not particularly limited, and any known method may be used.

In the production method of the present invention, the polyimide film can be produced by a thermal imidization method and a chemical imidization method.

Further, the polyimide resin can be produced by a composite imidization method using a thermal imidization method and a chemical imidization method in combination.

The thermal imidization method is a method of inducing imidization reaction by using a heat source such as a hot air dryer or an infrared dryer while excluding a chemical catalyst.

In the thermal imidization method, the gel film may be heat-treated at a variable temperature ranging from 100 to 600 ℃ to imidize the amide groups present in the gel film, and in detail, may be heat-treated at 200 to 500 ℃, and in more detail, may be heat-treated at 300 to 500 ℃ to imidize the amide groups present in the gel film.

However, a portion (about 0.1 to 10 mole%) of the amic acid may also undergo imidization during the formation of the gel film, and for this purpose, the polyamic acid composition may be dried at a variable temperature in the range of 50 to 200 ℃, which also falls within the scope of the thermal imidization method described above.

In the case of the chemical imidization method, a polyimide film may be manufactured using a dehydrating agent and an imidizing agent according to a method well known in the art.

As an example of the composite imidization method, a polyimide film may be produced by adding a dehydrating agent and an imidizing agent to a polyamic acid solution, heating at 80 to 200 ℃, preferably 100 to 180 ℃ to perform partial curing and drying, and then heating at 200 to 400 ℃ for 5 to 400 seconds.

The polyimide film of the present invention produced by the above-described production method may have a glass transition temperature (Tg) of 320 ℃ or higher, a moisture absorption rate of 0.4% or lower, and a dielectric loss tangent (Df) of 0.004 or lower.

The present invention provides a multilayer film comprising the polyimide film and a thermoplastic resin layer, and a flexible metal foil laminate comprising the polyimide film and a conductive metal foil.

As the thermoplastic resin layer, for example, a thermoplastic polyimide resin layer or the like can be applied.

The metal foil to be used is not particularly limited, and in the case of using the flexible metal foil laminate of the present invention in electronic equipment or electrical equipment applications, for example, a metal foil containing copper or copper alloy, stainless steel or an alloy thereof, nickel or nickel alloy (including 42 alloy), aluminum or aluminum alloy may be used.

In general, a copper foil such as a rolled copper foil or an electrolytic copper foil is often used for a flexible metal foil laminate, and the present invention can be preferably used. The surface of the metal foil may be coated with a rust preventive layer, a heat resistant layer, or an adhesive layer.

In the present invention, the thickness of the metal foil is not particularly limited as long as it can exert a sufficient function according to the application thereof.

The flexible metal foil laminate of the present invention may be a structure in which a metal foil is laminated on one surface of the polyimide film, or a structure in which an adhesive layer containing thermoplastic polyimide is attached to one surface of the polyimide film and the metal foil is laminated in a state in which the metal foil is attached to the adhesive layer.

The invention also provides an electronic component comprising the flexible metal foil laminate as an electrical signal transmission circuit. The above-mentioned electric signal transmission circuit may be an electronic component that performs signal transmission at a high frequency of at least 2GHz, specifically at a high frequency of at least 5GHz, more specifically at a high frequency of at least 10 GHz.

The electronic component may be, for example, a communication circuit for a portable terminal, a communication circuit for a computer, or a communication circuit for a spacecraft, but is not limited thereto.

Description of the embodiments

Hereinafter, the operation and effects of the invention will be described in more detail by means of specific examples of the invention. However, these examples are provided only as an illustration of the invention and the scope of the claims of the invention should not be limited thereto.

Example 1]

In a 500ml reactor equipped with a stirrer and a nitrogen gas injection/discharge tube, DMF was charged while nitrogen gas was injected, and after the temperature of the reactor was set to 30 ℃, m-tolidine (m-tolidine) and p-phenylenediamine as diamine components, and biphenyltetracarboxylic dianhydride as acid dianhydride components were charged, and complete dissolution was confirmed. After stirring for 120 minutes while heating the temperature to 40℃under a nitrogen atmosphere, a first polyamic acid having a viscosity at 23℃of 200,000cP was produced.

In a 500ml reactor equipped with a stirrer and a nitrogen gas injection/discharge tube, NMP was charged while nitrogen gas was injected, and after the temperature of the reactor was set to 30 ℃, m-tolidine as a diamine component, biphenyl tetracarboxylic dianhydride and pyromellitic dianhydride as acid dianhydride components were charged, and complete dissolution was confirmed. After stirring for 120 minutes while heating the temperature to 40℃under a nitrogen atmosphere, a second polyamic acid having a viscosity at 23℃of 200,000cP was produced.

Next, the first polyamic acid and the second polyamic acid were heated to 40 ℃ under a nitrogen atmosphere, and after stirring for 120 minutes, a third polyamic acid having a final viscosity at 23 ℃ of 200,000cp and comprising a diamine component and an acid dianhydride component was produced as shown in table 1 below.

The bubbles of the third polyamic acid produced above were removed by high-speed rotation at 1,500rpm or more. Then, the polyamic acid and the catalyst were mixed and stirred, and then cast into a film, and dried at a temperature of 90 to 200 ℃ in a nitrogen atmosphere for 30 minutes to produce a gel film, which was heated to 450 ℃ at a rate of 2 ℃/minute, heat-treated at 450 ℃ for 60 minutes, and then cooled to 30 ℃ at a rate of 2 ℃/minute, thereby obtaining a polyimide film.

Then, the polyimide film was peeled off from the glass substrate by immersing (dipping) in distilled water. The thickness of the polyimide film produced was 15. Mu.m. The thickness of the produced polyimide film was measured using an Anritsu film thickness meter (Electric Film thickness tester).

< examples 2 to 4 and comparative examples 1 to 5>

A polyimide film was produced in the same manner as in example 1, except that the components and the contents thereof were changed as shown in table 1 below in example 1.

TABLE 1

Experimental example

The polyimide films produced in examples 1 to 4 and comparative examples 1 to 5 were evaluated for moisture permeability, dielectric loss tangent, thermal characteristics (thermal expansion coefficient and glass transition temperature) and film forming characteristics, and the results thereof are shown in table 2 below.

(1) Moisture permeability rate

Moisture permeability was measured using a Permatran-W3/33 MA apparatus at 38.+ -. 2 ℃ under a 100% R.H environment (measurement basis according to ASTM F1249).

(2) Dielectric loss factor measurement

Dielectric loss factor (Df) was measured using a resistance tester Agilent 4294A by placing a flexible metal foil laminate for 72 hours.

(3) Measurement of thermal expansion coefficient

The Coefficient of Thermal Expansion (CTE) was measured by shearing a polyimide film into a film having a width of 4mm and a length of 20mm using a thermo-mechanical analyzer (thermomechanical analyzer) Q400 from TA corporation, heating the film from room temperature to 300 ℃ at a rate of 10 ℃/min while applying a tension of 0.05N under a nitrogen atmosphere, cooling the film at a rate of 10 ℃/min again, and measuring the slope in the range of 100 ℃ to 200 ℃.

(4) Glass transition temperature determination

Glass transition temperature (T) _g ) The loss modulus and storage modulus of each film were obtained by DMA, and the inflection point in the cut line graph of each film was measured as the glass transition temperature.

(5) Film Forming Property (evaluation of flatness)

Film formation characteristics were evaluated by visually observing the occurrence or non-occurrence of wrinkles in the polyimide films produced in the examples and comparative examples. The results are shown in Table 2 below.

< evaluation criterion >

O: no wrinkles appear and the flatness of the film is consistent

X: wrinkles occur and the flatness of the film is inconsistent

TABLE 2

As can be confirmed from table 2, the polyimide film manufactured according to the examples of the present invention exhibited an extremely low dielectric loss tangent of 0.003 or less, and the glass transition temperature was at a desired level. In addition, it was confirmed that the moisture permeability also showed excellent results, and that no wrinkles were generated to have excellent flatness, and therefore, the film forming property was good. The results are achieved by the specific components and composition ratios of the present application, and it is known that the content of each component plays a decisive role. In contrast, the polyimide films of comparative examples 1 to 5 showed not only higher dielectric loss tangent or lower glass transition temperature than the examples, but also lower results than the examples in terms of moisture permeability. In addition, in the cases of comparative examples 2 and 4, it was found that the flatness of the film was not uniform and the film forming property was poor due to the occurrence of wrinkles. From this, it is expected that the comparative example is difficult to be applied to an electronic component that performs signal transmission at high frequency in units of gigabits.

While the present invention has been described with reference to the embodiments thereof, those skilled in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above description.

Availability on production

The polyimide film of the embodiment of the present invention uses a specific acid dianhydride component and a specific diamine component in combination in a specific molar ratio, so that the moisture absorption rate and the moisture permeability can be minimized to have low dielectric characteristics and high heat resistance characteristics.

In addition, the present invention can realize high-speed communication at a high frequency of 10GHz or more by including the polyimide film as described above, and can be effectively applied to electronic components such as a flexible metal foil laminate.

Claims

1. A polyimide film produced by imidizing a polyamic acid solution containing an acid dianhydride component including biphenyltetracarboxylic acid dianhydride (BPDA) and pyromellitic acid dianhydride (PMDA), and a diamine component including m-tolidine and p-phenylenediamine (PPD),

2. The polyimide film according to claim 1, wherein the content of biphenyl tetracarboxylic dianhydride is 45 mol% or more and 65 mol% or less, and the content of pyromellitic dianhydride is 35 mol% or more and 55 mol% or less, based on 100 mol% of the total content of the acid dianhydride component.

3. The polyimide film according to claim 1, which comprises a block copolymer composed of 2 or more blocks.

4. The polyimide film of claim 1 comprising a block copolymer having a first block and a second block,

the first block is obtained by imidizing an acid dianhydride component containing biphenyl tetracarboxylic dianhydride with a diamine component containing meta-tolidine and para-phenylenediamine,

the second block is obtained by imidizing an acid dianhydride component containing biphenyl tetracarboxylic dianhydride and pyromellitic dianhydride with a diamine component containing m-toluidine.

5. The polyimide film according to claim 1, which has a glass transition temperature Tg of 300 ℃ or higher and a dielectric dissipation factor Df of 0.003 or lower.

6. The polyimide film according to claim 1, having a moisture permeability of 0.02 (g/(m) ² * Day) and/μm or less.

7. The polyimide film of claim 1 having a coefficient of thermal expansion of 15 to 18ppm/°c.

8. A method for producing a polyimide film, comprising:

(d) A step of forming a film of a precursor composition containing the third polyamic acid on a support and then imidizing the film,

the first acid dianhydride component and the second acid dianhydride component each contain one or more selected from the group consisting of biphenyl tetracarboxylic acid dianhydride BPDA and pyromellitic acid dianhydride PMDA,

the first diamine component and the second diamine component each comprise one or more selected from the group consisting of m-toluidine and p-phenylenediamine PPD,

9. The method for producing a polyimide film according to claim 8, wherein the biphenyl tetracarboxylic dianhydride content is 45 mol% or more and 65 mol% or less, and the pyromellitic dianhydride PMDA content is 35 mol% or more and 55 mol% or less, based on 100 mol% of the total content of the first acid dianhydride component and the second acid dianhydride component.

10. The method for producing a polyimide film according to claim 8, wherein the first polyamic acid contains an acid dianhydride component containing biphenyltetracarboxylic acid dianhydride and a diamine component containing m-toluidine and p-phenylenediamine,

the second polyamic acid includes an acid dianhydride component including biphenyl tetracarboxylic dianhydride and pyromellitic dianhydride, and a diamine component including m-toluidine.

11. The method for producing a polyimide film according to claim 8, wherein the polyimide film produced has a glass transition temperature Tg of 300 ℃ or higher and a dielectric dissipation factor Df of 0.003 or lower.

12. A multilayer film comprising the polyimide film of claim 1 and a thermoplastic resin layer.

13. A flexible metal foil laminate comprising the polyimide film of claim 1 and a conductive metal foil.

14. An electronic component comprising the flexible metal foil laminate of claim 13.