CN116194512A - Low dielectric polyimide film and method for producing same - Google Patents

Abstract

The present invention relates to a polyimide film produced by imidizing a polyamic acid solution containing an acid dianhydride component and a diamine component, and a method for producing the same, wherein the acid dianhydride component contains biphenyl Tetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA), the above-mentioned diamine components include m-tolidine (m-tolidine) and p-phenylenediamine (PPD), the total content of the above-mentioned diamine components is 100 Based on mol %, the content of the above-mentioned m-toluidine is not less than 30 mol % and not more than 50 mol %, and the content of the above-mentioned p-phenylenediamine is not less than 50 mol % and not more than 70 mol %.

Description

Low dielectric polyimide film and manufacturing method thereof

technical field

The present invention relates to a low-dielectric polyimide film with improved dielectric properties and a manufacturing method thereof.

Background technique

Polyimide (polyimide, PI) is based on the imide ring and rigid aromatic main chain with excellent chemical stability, and has the highest level of heat resistance, chemical resistance, electrical insulation, Chemical-resistant, weather-resistant polymer material.

In particular, due to excellent insulating properties, that is, excellent electrical properties such as low dielectric constant, it has attracted attention as a highly functional polymer material in the fields of electricity, electronics, and optics.

In recent years, with the development of light weight and miniaturization of electronic products, highly integrated and flexible thin circuit boards have been actively developed.

Such thin circuit boards tend to have a structure in which a circuit including a metal foil is formed on an easily bendable polyimide film having excellent heat resistance, low temperature resistance, and insulating properties in many cases.

As such a thin circuit board, a flexible metal clad laminate is mainly used, for example, a flexible copper clad laminate (FCCL) using a thin copper plate as the metal foil is included. In addition, polyimide is also used as a protective film, an insulating film, etc. of a thin circuit board.

On the other hand, since various functions are built into electronic equipment in recent years, the above-mentioned electronic equipment is required to have a fast calculation speed and communication speed. In order to meet this demand, thin-shaped circuit substrate.

However, in general polyimide, the actual situation is that the dielectric characteristics have not reached an excellent level enough to maintain sufficient insulation in high-frequency communication.

In addition, it is well known that the lower the dielectric properties of the insulator, the more the undesired stray capacitance and noise generation in the thin circuit board can be reduced, thereby solving the problem of communication delay to a large extent.

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

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

In addition, the more moisture the polyimide film contains, the greater the dielectric constant and the greater the dielectric loss factor. In the case of a polyimide film, it is suitable as a material for a thin circuit board due to its excellent inherent characteristics, but it is relatively susceptible to moisture due to the polar imide group, so the insulating characteristics may be reduced.

Therefore, the reality is that it is necessary to develop a polyimide film that maintains the mechanical properties, thermal properties, and chemical resistance properties specific to polyimide at a certain level and has low dielectric properties, especially dielectric loss tangent.

prior art literature

patent documents

(Patent Document 1) Korean Laid-Open Patent Publication No. 10-2015-0069318

Contents of the invention

technical issues

An object of the present invention is to provide a polyimide film having high heat-resistant properties, low dielectric properties, and low moisture absorption properties, and a method for producing the same.

To this end, a practical object of the invention is to provide specific embodiments thereof.

Solution to the problem

For the purpose as described above, one embodiment of the present invention provides a polyimide film produced by imidizing a polyamic acid solution containing an acid dianhydride component and a diamine component, the acid dianhydride The ingredients include biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA), and the above-mentioned diamine ingredients include m-tolidine and p-phenylenediamine (PPD),

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

In one embodiment, in the above-mentioned acid dianhydride component, the content of the above-mentioned biphenyltetracarboxylic dianhydride may be 45 mol% or more and 65 mol% or less based on 100 mol% of the total content of the acid dianhydride component, and pyromellitic acid The content of the dianhydride (PMDA) may be not less than 35 mol % and not more than 55 mol %.

In one embodiment, the said polyimide film may contain the block copolymer which consists of 2 or more blocks.

For example, it may contain a block copolymer having a first block and a second block in which the first block is formed by combining an acid dianhydride component containing biphenyltetracarboxylic dianhydride with m-tolidine It is obtained by imidization reaction with the diamine component of p-phenylenediamine. The above-mentioned second block is obtained by combining the acid dianhydride component containing biphenyltetracarboxylic dianhydride and pyromellitic dianhydride with m-toluidine The diamine component is obtained by imidization reaction.

The polyimide film may have a glass transition temperature (Tg) of 300° C. or higher, and a dielectric loss factor (Df) of 0.003 or lower.

In addition, the moisture permeability may be 0.02 ((g/(m ² *day))/μm) or less, and the thermal expansion coefficient may be 15 to 18 ppm/°C.

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

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

(c) the step of producing the third polyamic acid by copolymerizing the first polyamic acid and the second polyamic acid in an organic solvent; and

(d) a step of imidizing the precursor composition containing the above-mentioned third polyamic acid after forming a film on the support body,

The first acid dianhydride component and the second acid dianhydride component each contain at least one selected from the group consisting of biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA),

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

Based on 100 mol% of the total content of the above-mentioned first diamine component and the above-mentioned second diamine component, the content of the above-mentioned m-toluidine is 30 mol% or more and 50 mol% or less, and the content of the above-mentioned p-phenylenediamine is 50 mol%. % or more and 70 mol% or less.

In addition, the present invention provides a multilayer film comprising the aforementioned polyimide film and a thermoplastic resin layer.

In addition, the present invention provides a flexible metal foil laminate comprising the above polyimide film and a conductive metal foil.

In addition, an electronic component including the above-mentioned flexible metal foil laminate is provided.

Invention effect

The polyimide film according to the embodiment of the present invention uses a specific acid dianhydride component and a specific diamine component in combination at a specific molar ratio, thereby being able to minimize moisture absorption and moisture permeability while having low dielectric properties and High heat resistance properties.

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

Detailed ways

best practice

Hereinafter, the embodiment of the present invention will be described in more detail in the order of the "polyimide film" and the "manufacturing method of the polyimide film" of the present invention.

Prior to this, the terms or vocabulary used in this specification and the scope of the claims should not be limited to the usual or dictionary meanings for interpretation, but should only be based on the concept that the inventor can properly define the terms to use the best The method explains the principle of its invention, and explains it in accordance with the meaning and concept of the technical idea of the present invention.

Therefore, the configuration of the embodiment recorded in this specification is only the most preferred embodiment of the present invention, and does not represent all the technical ideas of the present invention. Therefore, it should be understood that there may be many alternatives to these embodiments when filing this application. Equivalents and modifications.

In this specification, expressions in the singular include expressions in the plural unless the context clearly dictates otherwise. In this specification, it should be understood that terms such as "comprising", "having" or "having" are intended to specify the presence of implemented features, numbers, steps, constituent elements or combinations thereof, not to preclude more than one other feature , numbers, steps, constituent elements or their combinations exist or additional possibilities.

In this specification, where amounts, concentrations or other values or parameters are given as ranges, preferred ranges or enumerations of preferred upper limits and preferred lower limits, it should be understood that the ranges are specifically All ranges formed by any pair of any upper range limit or preferred value and any lower range limit or preferred value are disclosed.

Where a numerical range is referred to in this specification, unless otherwise stated, that range is intended to include the endpoints and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values mentioned when defining the range.

In this specification, "dianhydrides" are intended to include precursors or derivatives thereof, which, while technically may not be dianhydrides, will still react with diamines to form polyamic acids, which can again be transformed into For polyimide.

In this specification, "diamine" is intended to include precursors or derivatives thereof which, although technically may not be diamines, will still react with dianhydrides to form polyamic acids which can be converted again into polyamic acids. imide.

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

The acid dianhydride component may contain one or more types selected from the group consisting of biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA).

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

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

In the present invention, the crystallinity of the film can be realized by the aforementioned biphenyltetracarboxylic dianhydride (BPDA) and m-toluidine (m-tolidine).

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

Preferably, the content of the m-toluidine mentioned above may be not less than 30 mol % and not more than 50 mol %. Such m-toluidine especially has a hydrophobic methyl group, and thus can contribute to the low moisture absorption property of the polyimide film.

In the present invention, when the diamine component contains m-toluidine and p-phenylenediamine in the above content range, it has low dielectric characteristics and can have low transmission loss characteristics even at high frequencies.

Among the above-mentioned acid dianhydride components, the content of the above-mentioned biphenyltetracarboxylic dianhydride (BPDA) can be 45 mol% or more and 65 mol% or less based on 100 mol% of the total content of the acid dianhydride components, and pyromellitic dianhydride The content of (PMDA) may be not less than 35 mol % and not more than 55 mol %.

Preferably, the biphenyltetracarboxylic dianhydride (BPDA) content may be 45 mol% to 55 mol%, and the pyromellitic dianhydride (PMDA) content may be 45 mol% to 55 mol%. In the case where the above-mentioned acid dianhydride component contains biphenyltetracarboxylic dianhydride and pyromellitic dianhydride (PMDA) in the above-mentioned content range, the mechanical properties of the polyimide film can be improved, and the polyimide film suitable for manufacturing flexible metal foil can be ensured. Laminate horizontal heat resistance. In addition, there is an advantage in favor of securing a desired level of dielectric loss factor and moisture permeability.

In the present invention, the polyimide chain derived from biphenyltetracarboxylic dianhydride has a structure called a charge transfer complex (CTC: Charge transfer complex), that is, an electron donor (electron donnor) and an electron acceptor ( Electron acceptor) regular linear structure close to each other, intermolecular interaction (intermolecular interaction) is strengthened.

Such a structure has an effect of preventing hydrogen bond formation with moisture, and thus can exert an influence on reducing the moisture absorption rate to maximize the effect of reducing the moisture permeability of the polyimide film.

Moreover, since the pyromellitic dianhydride contained as the said acid dianhydride component has a relatively rigid structure and can provide suitable elasticity to a polyimide film, it is preferable from this point.

In order for the polyimide film to satisfy both the appropriate elasticity and the moisture absorption rate, the content ratio of the acid dianhydride is particularly important. For example, the lower the content ratio of biphenyltetracarboxylic dianhydride, the more difficult it is to expect a low moisture absorption rate due to the above-mentioned CTC structure.

In addition, biphenyltetracarboxylic dianhydride contains two benzene rings corresponding to the aromatic moiety, and pyromellitic dianhydride contains one benzene ring corresponding to the aromatic moiety.

In the acid dianhydride component, when the molecular weight is the same, the increase of the pyromellitic dianhydride content can be understood as the increase of the imide group in the molecule. This is understood to be that the ratio of the imide group derived from the above-mentioned pyromellitic dianhydride in the polyimide polymer chain is relatively increased compared with the imide group derived from biphenyltetracarboxylic dianhydride.

That is, an increase in the content of pyromellitic dianhydride can also be regarded as a relative increase in the imide group with respect to the entire polyimide film, so it is difficult to expect a low moisture absorption rate.

On the contrary, if the content ratio of pyromellitic dianhydride is decreased, the components of the rigid structure are relatively decreased, and the mechanical properties of the polyimide film may decrease below a desired level.

For this reason, when the content of the biphenyltetracarboxylic dianhydride is higher than the above range, the mechanical properties of the polyimide film decrease, and heat resistance at a level suitable for manufacturing a flexible metal foil laminate cannot be ensured.

Conversely, in the case where the content of the above-mentioned biphenyltetracarboxylic dianhydride is lower than the above range or the content of pyromellitic dianhydride is higher than the above range, it is difficult to achieve an appropriate level of dielectric constant, dielectric loss factor, and moisture absorption rate. , so it is not good.

In one embodiment, the said polyimide film may contain the block copolymer which consists of 2 or more blocks, for example, may contain 2 blocks.

Each of the above two blocks can be obtained by imidating an acid dianhydride component containing biphenyltetracarboxylic dianhydride and a diamine component containing m-tolidine and p-phenylenediamine. and a second block obtained by subjecting an acid dianhydride component containing biphenyltetracarboxylic dianhydride and pyromellitic dianhydride to an imidization reaction with a diamine component containing m-toluidine .

Thus, the above-mentioned first block and second block can be formed by imidation reaction of each specific monomer.

The polyimide film of the present invention includes a first block that has film forming processability and low dielectric characteristics due to heat resistance, and a second block that enhances low dielectric characteristics due to crystallinity, thereby being able to express Target high heat-resistant properties, low dielectric properties, and low moisture absorption properties.

For example, when forming the above-mentioned first block, the contents of biphenyltetracarboxylic dianhydride, m-tolidine and p-phenylenediamine can be appropriately adjusted as required to ensure high heat resistance and low dielectric properties . That is, the polyimide film of the present invention can secure a glass transition temperature (Tg) of 300° C. or higher and a dielectric loss factor (Df) of 0.003 or lower, and thus can exhibit high heat resistance and low dielectric properties.

In addition, the above-mentioned polyimide film can be realized by adjusting the crystallinity by including the second block of biphenyltetracarboxylic dianhydride and m-tolidine, thereby minimizing the moisture absorption rate and moisture permeability rate. Improvement of low dielectric properties.

Further, the present invention has a thermal expansion coefficient of 15 to 18 ppm/°C similar to that of copper foil by appropriately controlling the content of biphenyltetracarboxylic dianhydride used when forming the above-mentioned second block as required, so that the interlayer dimension can be ensured. stability.

As described above, the glass transition temperature (Tg) of the polyimide film of the present invention may be 300° C. or higher, and the dielectric dissipation factor (Df) may be 0.003 or lower. In addition, the moisture permeability may be 0.02 ((g/(m ² *day))/μm) or less, and the thermal expansion coefficient may be 15 to 18 ppm/°C.

In this regard, polyimide films satisfying the ranges of the above-mentioned dielectric dissipation factor (Df), glass transition temperature, moisture permeability and/or thermal expansion coefficient can be used as insulating films for flexible metal foil laminates, not only that, even if the The manufactured flexible metal foil laminate is used in an electrical signal transmission circuit that transmits signals at a high frequency of 10 GHz or higher, and can also ensure insulation stability and minimize signal transmission delay.

The above "dielectric dissipation factor" refers to the force dissipated by a dielectric body (or insulator) when molecular friction hinders molecular motion caused by an alternating electric field.

The value of the dielectric loss factor is generally used as an index indicating the easiness of charge loss (dielectric loss). The higher the dielectric loss factor, the easier it is for the charge to disappear. Conversely, the lower the dielectric loss factor, the less likely it is for the charge to disappear. That is, the dielectric loss factor is a measure of power loss, and as the dielectric loss factor becomes smaller, it is possible to reduce signal transmission delay caused by power loss while maintaining a high communication speed.

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

The above-mentioned moisture permeability indicates the amount of moisture contained in the material, and it is generally known that the dielectric constant and the dielectric loss factor increase when the moisture permeability is high.

Generally, it is known that the dielectric constant of water is 100 or more when it is solid, about 80 when it is liquid, and 1.0059 when it is water vapor in gaseous state.

For example, in the state where the polyimide film absorbs water vapor and the like, water exists in a liquid state. At this time, the dielectric constant and dielectric loss factor of the polyimide film will be significantly increased.

In other words, the dielectric constant and dielectric loss tangent of the polyimide film may change rapidly even when a small amount of water is absorbed.

The moisture permeability of the polyimide film of the present invention can be 0.02 ((g/(m ² *day))/μm) or less, and this achievement is attributed to the characteristics of the composition of the polyimide film of the present invention.

This will be described more specifically later, and it appears that this is due to the fact that the molecular structure of the polyimide film of the present invention contains a nonpolar portion.

As described above, the polyimide film of the present invention satisfies all the above-mentioned conditions, so it can be used as an insulating film for flexible metal foil laminates, not only that, but also can ensure insulation stability even at high frequencies, and can also enable signal transmission Latency is minimized.

Among the present invention, the manufacture of polyamic acid can exemplify following method:

(1) A method in which all diamine components are added to a solvent, and then an acid dianhydride component is added in a substantially equimolar manner with the diamine component to perform polymerization;

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

(3) After adding a part of the diamine component to the solvent, mix a part of the acid dianhydride component at a ratio of about 95 to 105 mol% with respect to the reaction component, then add the remaining diamine component, and then add A method of polymerizing the remaining acid dianhydride component, thereby the diamine component and the acid dianhydride component become substantially equimolar;

(4) After adding the acid dianhydride component to the solvent, mix a part of the diamine compound at a ratio of about 95 to 105 mol% with respect to the reaction component, then add the other acid dianhydride component, and then add the remaining diamine Components, so that the diamine component and the acid dianhydride component are polymerized in a substantially equimolar manner;

(5) In a solvent, a part of the diamine component and a part of the acid dianhydride component are reacted in excess to form the first composition, and in another solvent, a part of the diamine component and a part of the acid dianhydride component are reacted to form the first composition. Either react in excess to form a second composition, and then mix the first and second compositions to complete the polymerization. At this time, when forming the first composition, if the diamine component is excessive, then in the second In the second composition, the acid dianhydride component is excessive, and if the acid dianhydride component is excessive in the first composition, then the diamine component is excessive in the second composition, thereby mixing the first and second compositions and mixing them A method of polymerizing the overall diamine component and the acid dianhydride component used during the reaction so as to be substantially equimolar; and the like.

However, the above-mentioned polymerization method is not limited to the above-mentioned examples, and it is needless to say that any known method can be used for the production of the above-mentioned first to third polyamic acids.

In a specific example, the manufacture method of polyimide film of the present invention can comprise:

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

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

(c) the step of producing the third polyamic acid by copolymerizing the first polyamic acid and the second polyamic acid in an organic solvent; and

(d) The step of imidating the precursor composition containing the above-mentioned third polyamic acid after forming a film on the support body.

Each of the first acid dianhydride component and the second acid dianhydride component may contain one or more species selected from the group consisting of biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA).

Moreover, the said 1st diamine component and 2nd diamine component contain 1 or more types chosen from the group which consists of m-tolidine and p-phenylenediamine (PPD), It is characterized by the above-mentioned.

Based on 100 mol% of the total content of the above-mentioned first diamine component and the above-mentioned second diamine component, the content of the above-mentioned m-toluidine can be 30 mol% or more and 50 mol% or less, and the content of the above-mentioned p-phenylenediamine can be 50 mol% or more and 70 mol% or less.

In addition, based on 100 mol% of the total content of the first acid dianhydride component and the second acid dianhydride component, the content of the above-mentioned biphenyltetracarboxylic dianhydride may be 45 mol% or more and 65 mol% or less. The content of formic dianhydride (PMDA) may be not less than 35 mol % and not more than 55 mol %.

Preferably, the above-mentioned first polyamic acid may contain an acid dianhydride component containing biphenyltetracarboxylic dianhydride and a diamine component containing m-tolidine and p-phenylenediamine, and the above-mentioned second polyamic acid An acid dianhydride component containing biphenyltetracarboxylic dianhydride and pyromellitic dianhydride, and a diamine component containing m-toluidine may be contained.

In the present invention, the polymerization method of the above-mentioned polyamic acid can be defined by any (random) polymerization method, and the polyimide film manufactured by the polyamic acid of the present invention manufactured by the above-mentioned process can be It is preferably used in terms of maximizing the effect of the present invention of reducing the dielectric loss factor (Df) and the moisture absorption rate and moisture permeability rate.

However, the above-mentioned polymerization method can make the length of the repeating unit in the polymer chain described above shorter, so there may be limitations in making use of the excellent properties of the polyimide chain derived from the acid dianhydride component. . Therefore, the polymerization method of the polyamic acid that can be used particularly preferably 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 can be used as long as it dissolves the polyamic acid, and an amide-based solvent is preferable.

Specifically, the above-mentioned solvent can be an organic polar solvent, in detail, it can be an aprotic polar solvent (aprotic polar solvent), for example, it can be selected from N,N-dimethylformamide (DMF), N , more than one of the group consisting of N-dimethylacetamide, N-methyl-pyrrolidone (NMP), γ-butyrolactone (GBL), diglyme (Diglyme), but not limited thereto , can be used alone or in combination of two or more as needed.

In one example, N,N-dimethylformamide and N,N-dimethylacetamide can be used particularly preferably as the above-mentioned solvent.

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

The particle size of the filler is not particularly limited, as long as it is determined according to the properties of the membrane to be modified and the type of filler to be added. Generally, the average particle diameter is 0.05 to 100 μm, preferably 0.1 to 75 μm, more preferably 0.1 to 50 μm, particularly preferably 0.1 to 25 μm.

If the particle size is smaller than the above range, the modification effect is less likely to be exhibited, and if it is larger than the above range, the surface properties may be greatly impaired or the mechanical properties may be greatly reduced.

In addition, the addition amount of the filler is not particularly limited, as long as it is determined according to the membrane properties to be modified, the particle size of the filler, and the like. Generally, the addition amount of a filler is 0.01-100 weight part with respect to 100 weight part of polyimides, Preferably it is 0.01-90 weight part, More preferably, it is 0.02-80 weight part.

If the amount of the filler added is less than the above range, the modification effect by the filler will not be easily exhibited, and if it is more than the above range, the mechanical properties of the film may be greatly damaged. The method of adding the filler is not particularly limited, and any known method can be used.

In the manufacturing method of this invention, a polyimide film can be manufactured by thermal imidization method and chemical imidization method.

In addition, it can also be produced by a composite imidization method in which a thermal imidization method and a chemical imidization method are used in combination.

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

In the thermal imidization method, the amic acid groups present in the gel film may be imidized by heat-treating the gel film at a variable temperature in the range of 100 to 600° C., in detail, The heat treatment may be performed at 200 to 500° C., more specifically, at 300 to 500° C. to imidize the amic acid group present in the gel film.

However, a part (about 0.1 mol% to 10 mol%) of the amic acid may also be imidized in the process of forming a gel film. Drying the polyamic acid composition also belongs to the category of the thermal imidization method described above.

In the case of the chemical imidization method, a polyimide film can be produced using a dehydrating agent and an imidization agent according to a method known in the art.

As an example of the composite imidization method, after adding a dehydrating agent and an imidization agent to the polyamic acid solution, it can be partially cured and dried by heating at 80 to 200°C, preferably at 100 to 180°C, Then, it is heated at 200 to 400° C. for 5 to 400 seconds, thereby manufacturing a polyimide film.

The glass transition temperature (Tg) of the polyimide film of the present invention manufactured according to the above-mentioned manufacturing method may be 320° C. or more, the moisture absorption rate may be 0.4% or less, and the dielectric loss factor (Df) may be 0.004. the following.

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

As the above-mentioned 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 when the flexible metal foil laminate of the present invention is used for electronic equipment or electric equipment, for example, copper or copper alloys, stainless steel or alloys thereof, nickel or nickel may be used. Metal foils of alloys (also including alloy 42), aluminum or aluminum alloys.

Copper foils such as rolled copper foils and electrolytic copper foils are often used in general flexible metal foil laminates, but they can also be preferably used in the present invention. In addition, the surface of these metal foils may be coated with a rust-proof layer, a heat-resistant layer, or an adhesive layer.

In this invention, the thickness of the said metal foil is not specifically limited, What is necessary is just the thickness which can exhibit sufficient function according to the use.

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

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

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

Implementation

Hereinafter, the functions and effects of the invention will be described in more detail through specific embodiments of the invention. However, these Examples are provided merely as illustrations of the invention, and the scope of claims for the invention is not limited thereto.

<Example 1>

Into a 500ml reactor equipped with a stirrer and a nitrogen injection/exhaust pipe, inject DMF while injecting nitrogen, set the temperature of the reactor to 30°C, and inject m-tolidine as a diamine component Complete dissolution was confirmed with p-phenylenediamine and biphenyltetracarboxylic dianhydride which is an acid dianhydride component. In a nitrogen atmosphere, stirring was continued for 120 minutes while heating the temperature to 40° C., and the first polyamic acid having a viscosity of 200,000 cP at 23° C. was produced.

Into a 500ml reactor equipped with a stirrer and a nitrogen injection/exhaust pipe, inject NMP while injecting nitrogen, set the temperature of the reactor to 30°C, and inject m-toluidine as a diamine component, acid dianhydride The components of biphenyltetracarboxylic dianhydride and pyromellitic dianhydride were confirmed to be completely dissolved. In a nitrogen atmosphere, stirring was continued for 120 minutes while heating up the temperature to 40° C., and the viscosity at 23° C. showed a second polyamic acid of 200,000 cP was produced.

Next, under a nitrogen atmosphere, while heating the temperature to 40°C, the above-mentioned first polyamic acid and the second polyamic acid were continuously stirred for 120 minutes, and the final viscosity at 23°C was 200,000cP as follows: The 3rd polyamic acid containing a diamine component and an acid dianhydride component as shown in Table 1.

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

Then, the polyimide film was peeled from the glass substrate by immersing (dipping) in distilled water. The thickness of the produced polyimide film was 15 μm. The thickness of the produced polyimide film was measured using the electric film thickness tester of Anritsu Corporation.

<Examples 2 to 4 and Comparative Examples 1 to 5>

In Example 1, the polyimide film was manufactured by the method similar to Example 1 except having changed the component and its content, respectively, as shown in following Table 1.

[Table 1]

Experimental example

For the polyimide films produced in Examples 1 to 4 and Comparative Examples 1 to 5, respectively, the moisture permeability, dielectric dissipation factor, thermal characteristics (thermal expansion coefficient and glass transition temperature) and film formation were evaluated. properties, and the results are shown in Table 2 below.

(1) Moisture permeability

The moisture permeability is measured using Permatran-W 3/33MA equipment at 38±2°C and 100% R.H environment (the measurement standard is based on ASTM F1249).

(2) Measurement of dielectric loss factor

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

(3) Measurement of thermal expansion coefficient

Coefficient of thermal expansion (CTE) uses the thermomechanical analyzer (thermomechanical analyzer) Q400 type of TA company, after the polyimide film is cut into wide 4mm, long 20mm, under nitrogen atmosphere, while applying the tension force of 0.05N, After heating from room temperature to 300°C at a rate of 10°C/min, it was cooled again at a rate of 10°C/min, and the slope between 100°C and 200°C was measured at this time.

(4) Determination of glass transition temperature

As for the glass transition temperature (T _g ), the loss modulus and the storage modulus of each film were obtained by DMA, and the inflection point in their tangent diagram was measured as the glass transition temperature.

(5) Film-forming properties (evaluation of flatness)

Film-forming properties were evaluated by visually observing the presence or absence of wrinkles in the polyimide films produced in the above Examples and Comparative Examples. The results are shown in Table 2 below.

<Evaluation criteria>

○: There are no wrinkles, and the flatness of the film is consistent

X: There are wrinkles, and the flatness of the film is inconsistent

[Table 2]

From Table 2, it can be confirmed that the polyimide film produced according to the example of the present invention exhibited an extremely low dielectric loss factor of 0.003 or less, and the glass transition temperature was at a desired level. In addition, it was confirmed that the water vapor transmission rate also showed an excellent result, and that there were no wrinkles and excellent flatness, so it was found that the film-forming property was good. Such a result was achieved by the specific components and composition ratio of the present application, and it can be seen that the content of each component plays a decisive role. On the contrary, the polyimide films of Comparative Examples 1 to 5 not only have a higher dielectric loss factor or a lower glass transition temperature than those of Examples, but also show lower moisture permeability than Examples. the result of. In addition, in the case of Comparative Examples 2 and 4, it was found that due to the occurrence of wrinkles, the flatness of the film was not uniform, and the film-forming property was not good. From this, it can be predicted that it is difficult to apply the comparative example to an electronic component that performs signal transmission at a high frequency in units of gigabytes.

The above has been described with reference to the embodiments of the present invention, but those skilled in the art to which the present invention pertains should be able to perform various applications and modifications within the scope of the present invention based on the above-mentioned contents.

production availability

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

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

Claims (14)

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),

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.

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:

(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 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,

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.

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.