WO2022065804A1 - Low-dielectric-constant polyimide film and manufacturing method therefor - Google Patents

Abstract

The present invention relates to a polyimide film and a manufacturing method therefor, the polyimide film being manufactured by imidizing a polyamic acid solution comprising: an acid dianhydride component comprising a biphenyltetracarboxylic dianhydride (BPDA) and a pyromellitic dianhydride (PMDA); and a diamine component comprising m-tolidine and p-phenylenediamine (PPD), wherein, on the basis of 100 mol% of the total amount of the diamine component, the amount of m-tolidine is 30-50 mol% and the amount of PPD is 50-70 mol%.

Description

Low dielectric polyimide film and manufacturing method thereof

The present invention relates to a low-k polyimide film having improved dielectric properties and a method for manufacturing the same.

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

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

In recent years, as electronic products become lighter and smaller, thin circuit boards with a high degree of integration and flexibility are being actively developed.

Such a thin circuit board has a structure in which a circuit including a metal foil is formed on a polyimide film that is easy to bend while having excellent heat resistance, low temperature resistance and insulating properties is widely used.

As such a thin circuit board, a flexible metal clad laminate is mainly used, and as an example, a 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 and insulating film for thin circuit boards.

On the other hand, as various functions are embedded in electronic devices in recent years, fast operation speed and communication speed are required for the electronic devices.

However, in the case of conventional polyimide, the dielectric properties are not excellent enough to maintain sufficient insulation in high-frequency communication.

In addition, it is known that, as the insulator has a low dielectric characteristic, it is possible to reduce the occurrence of undesirable stray capacitance and noise in the thin circuit board, thereby substantially solving the cause of communication delay.

Therefore, polyimide with low dielectric properties is recognized as the most important factor in the performance of thin circuit boards.

In particular, in the case of high-frequency communication, dielectric dissipation inevitably occurs through polyimide. Dielectric dissipation factor (Df) refers to the degree of dissipation of electrical energy in a thin circuit board, and is closely related to the signal propagation delay that determines communication speed. It is recognized as an important factor in the performance of the substrate.

In addition, as the polyimide film contains more moisture, the dielectric constant increases and the dielectric loss factor increases. In the case of a polyimide film, it is suitable as a material for a thin circuit board due to its excellent intrinsic properties, but may be relatively vulnerable to moisture due to polar imide groups, which may deteriorate insulation properties.

Accordingly, there is a need to develop a polyimide film having dielectric properties, particularly low dielectric loss, while maintaining the mechanical properties, thermal properties, and chemical resistance properties unique to polyimide at a certain level.

[Prior art literature]

[Patent Literature]

(Patent Document 1) Republic of Korea Patent Publication No. 10-2015-0069318

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

Accordingly, it is a practical object of the present invention to provide specific examples thereof.

One embodiment of the present invention for achieving the above object is a dianhydride component comprising a biphenyltetracarboxylic dianhydride (BPDA) and a pyromellitic dianhydride (PMDA); and

It is prepared by imidizing a polyamic acid solution containing a diamine component including m-tolidine and paraphenylene diamine (PPD),

Based on 100 mol% of the total content of the diamine component, the content of m-tolidine is 30 mol% or more and 50 mol% or less, and the content of paraphenylene diamine is 50 mol% or more and 70 mol% or less, polyimide film is provided.

In one embodiment, in the dianhydride component, the content of the biphenyltetracarboxylic dianhydride is 45 mol% or more and 65 mol% or less, based on 100 mol% of the total content of the dianhydride component, and pyromelliticdian The content of hydride (PMDA) may be 35 mol% or more and 55 mol% or less.

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

For example, a first block obtained by imidizing a dianhydride component containing biphenyltetracarboxylic dianhydride and a diamine component containing m-tolidine and paraphenylene diamine; and

A second block obtained by imidizing a dianhydride component containing biphenyltetracarboxylic dianhydride and pyromellitic dianhydride and a diamine component containing m-tolidine; can do.

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

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

Another embodiment of the present invention comprises the steps of: (a) polymerizing a first dianhydride component and a first diamine component in an organic solvent to prepare a first polyamic acid;

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

(c) preparing a third polyamic acid by copolymerizing the first polyamic acid and the second polyamic acid in an organic solvent; and

(d) forming a film of the precursor composition including the third polyamic acid on a support, followed by imidization;

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

The first diamine component and the second diamine component each include at least one selected from the group consisting of m-tolidine and paraphenylene diamine (PPD),

Based on 100 mol% of the total content of the first diamine component and the second diamine component, the content of m-tolidine is 30 mol% or more and 50 mol% or less, and the content of paraphenylene diamine is 50 mol% or more It provides a method for producing a polyimide film, which is 70 mol% or less.

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

In addition, the present invention provides a flexible metal clad laminate comprising the above-described polyimide film and an electrically conductive metal foil.

In addition, it provides an electronic component including the flexible metal clad laminate.

The polyimide film according to the embodiment of the present invention can have low dielectric properties and high heat resistance properties by minimizing moisture absorption and air permeability by using a specific dianhydride component and a specific diamine component in a specific molar ratio in combination.

In addition, the present invention can implement high-speed communication at a high frequency of 10 GHz or more including the polyimide film as described above, and thus can be usefully applied to electronic components such as flexible metal clad laminates.

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

Prior to this, the terms or words used in the present specification and claims should not be construed as being limited to conventional or dictionary meanings, and the inventor should properly understand the concept of the term in order to best describe his invention. Based on the principle that it can be defined, it should be interpreted as meaning and concept consistent with the technical idea of the present invention.

Accordingly, since the configuration of the embodiments described in the present specification is only one of the most preferred embodiments of the present invention and does not represent all the technical spirit of the present invention, various equivalents and modifications that can be substituted for them at the time of the present application It should be understood that examples may exist.

In this specification, the singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as "comprise", "comprising" or "have" are intended to designate the existence of an embodied feature, number, step, element, or a combination thereof, but one or more other features or It should be understood that the existence or addition of numbers, steps, elements, or combinations thereof, is not precluded in advance.

Where an amount, concentration, or other value or parameter is given herein as a range, a preferred range, or a recitation of a preferred upper value and a lower preferred value, any pair of any upper limit of the range or It is to be understood that the preferred values and any lower range limits or all ranges formed by the preferred values are specifically disclosed.

When a range of numerical values is recited herein, the range is intended to include the endpoints and all integers and fractions within the range, unless otherwise stated. It is intended that the scope of the invention not be limited to the particular values recited when defining the ranges.

As used herein, “dianhydride” is intended to include precursors or derivatives thereof, which may not technically be dianhydride acids, but will nevertheless react with a diamine to form a polyamic acid, which in turn is a polyamic acid can be converted into mids.

As used herein, "diamine" is intended to include precursors or derivatives thereof, which may not technically be diamines, but will nevertheless react with dianhydrides to form polyamic acids, which in turn are polyamic acids. can be converted into mids.

The polyimide film according to the present invention is prepared by imidizing a polyamic acid solution containing a dianhydride component and a diamine component.

The dianhydride component may include at least one selected from the group consisting of biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA).

The diamine component may include at least one selected from the group consisting of m-tolidine and paraphenylene diamine (PPD).

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

The present invention can implement the crystallinity of the film through the biphenyltetracarboxylic dianhydride (BPDA) and m-tolidine (m-tolidine).

According to one embodiment of the present invention, in the diamine component, the content of m-tolidine is 0 mol% or more and 50 mol% or less, based on 100 mol% of the total content of the diamine component, and the content of paraphenylene diamine It may be 50 mol% or more and 70 mol% or less.

Preferably, the m-tolidine may be included in an amount of 30 mol% or more and 50 mol% or less. Such m-tolidine has a particularly hydrophobic methyl group, and thus may contribute to the low moisture absorption properties of the polyimide film.

In the present invention, when m-tolidine and paraphenylene diamine are included in the diamine component in the above content range, low dielectric properties may be obtained and low transmission loss characteristics may be obtained even at high frequencies.

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

Preferably, the content of the biphenyltetracarboxylic dianhydride (BPDA) is 45 mol% or more and 55 mol% or less, and the content of the pyromellitic dianhydride (PMDA) is 45 mol% or more and 55 mol% or less can When biphenyltetracarboxylic dianhydride and pyromellitic dianhydride (PMDA) are included in the above-mentioned content range in the dihydrate component, the mechanical properties of the polyimide film are improved, and to prepare a flexible metal clad laminate It is possible to secure an appropriate level of heat resistance. In addition, there are advantageous advantages in securing desired levels of dielectric loss rate and moisture permeability.

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

Since this structure has an effect of preventing hydrogen bonding with moisture, it can affect the lowering of the moisture absorption rate of moisture, thereby maximizing the effect of lowering the moisture permeability of the polyimide film.

In addition, the pyromellitic dianhydride included as the dianhydride component is preferable in that it has a relatively rigid structure and can impart appropriate elasticity to the polyimide film.

In order for the polyimide film to simultaneously satisfy appropriate elasticity and moisture absorption, the content ratio of dianhydride is particularly important. For example, as the content ratio of biphenyltetracarboxylic dianhydride decreases, it becomes difficult to expect a low moisture absorption rate due to the CTC structure.

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

An increase in the pyromellitic dianhydride content in the dianhydride component can be understood as an increase in the imide group in the molecule based on the same molecular weight. It can be understood that the ratio of the imide groups derived from the pyromellitic dianhydride in the polyimide polymer chain is relatively increased compared to the imide groups derived from the biphenyltetracarboxylic dianhydride.

That is, the increase in the pyromellitic dianhydride content can be seen as a relative increase in the imide group for the entire polyimide film, and thus it is difficult to expect a low moisture absorption rate.

Conversely, when the content ratio of pyromellitic dianhydride is reduced, a component having a relatively rigid structure is reduced, and thus the mechanical properties of the polyimide film may be lowered to a desired level or less.

For this reason, when the content of biphenyltetracarboxylic dianhydride exceeds the above range, mechanical properties of the polyimide film are deteriorated, and heat resistance at an appropriate level for manufacturing a flexible metal clad laminate cannot be secured.

Conversely, when the content of biphenyltetracarboxylic dianhydride is less than the above range or the content of pyromellitic dianhydride exceeds the above range, an appropriate level of dielectric constant, dielectric loss rate and moisture absorption rate are achieved. This is difficult because it is not preferable.

In one embodiment, the polyimide film may include a block copolymer consisting of two or more blocks, for example, may include two blocks.

Each of the two blocks is a first block obtained by imidating a dianhydride component containing biphenyltetracarboxylic dianhydride and a diamine component containing m-tolidine and paraphenylene diamine. ; and a second block obtained by imidizing a dianhydride component including biphenyltetracarboxylic dianhydride and pyromellitic dianhydride and a diamine component including m-tolidine.

As such, the first block and the second block may be formed by imidation of specific monomers, respectively.

The polyimide film according to the present invention includes a first block having low dielectric properties and film forming processability through heat resistance and a second block for strengthening low dielectric properties through crystallinity to achieve desired high heat resistance, low dielectric properties and low dielectric properties. It may exhibit hygroscopic properties.

For example, when the first block is formed, the contents of biphenyltetracarboxylic dianhydride, m-tolidine and paraphenylene diamine are appropriately adjusted as needed to achieve high heat resistance and low dielectric properties. characteristics can be obtained. 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 less, thereby exhibiting high heat resistance and low dielectric properties.

In addition, the polyid film controls crystallization through a second block containing biphenyltetracarboxylic dianhydride and m-tolidine to minimize moisture absorption and moisture permeability, thereby improving low dielectric strength. properties can be implemented.

Furthermore, the present invention provides interlayer dimensional stability by appropriately controlling the content of biphenyltetracarboxylic dianhydride used in forming the second block as necessary to have a coefficient of thermal expansion of 15 to 18 ppm/℃ similar to copper foil. can be obtained

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

In this regard, the polyimide film satisfying the above-described dielectric loss factor (Df), glass transition temperature, moisture permeability and/or thermal expansion coefficient range can be used as an insulating film for flexible metal clad laminates, and the manufactured flexible metal clad laminate Even if it is used as an electrical signal transmission circuit that transmits a signal at a high frequency of GHz or higher, its insulation stability can be secured and signal transmission delay can be minimized.

The "dielectric loss factor" means a force dissipated by a dielectric (or insulator) when friction of molecules interferes with molecular motion caused by an alternating electric field.

The value of the dielectric loss factor is commonly used as an index indicating the ease of dissipation of electric charge (dielectric loss). The higher the dielectric loss factor, the easier it is to dissipate the charge. there is. That is, since the dielectric loss factor is a measure of power loss, the lower the dielectric loss factor, the faster the communication speed can be maintained while signal transmission delay due to power loss is alleviated.

This is strongly required for the polyimide film, which is an insulating film, and the polyimide film according to the present invention may have a dielectric loss factor of 0.004 or less under a very high frequency of 10 GHz.

The moisture permeability, which indicates the amount of moisture contained in the material, is generally known to increase the dielectric constant and dielectric loss rate when the moisture permeability is high.

In general, it is known that when water is in a solid state, the dielectric constant is greater than 100, in a liquid state, about 80, and when water vapor in a gaseous state, it is 1.0059.

For example, water exists in a liquid state while water vapor is absorbed into the polyimide film. In this case, the dielectric constant and dielectric loss factor of the polyimide film may be dramatically increased.

That is, the dielectric constant and dielectric loss factor of the polyimide film may change rapidly with only a small amount of moisture absorption.

The polyimide film according to the present invention may have a moisture permeability of 0.02 (g/(m ² *day))/㎛) or less, and the achievement of this is due to the structural characteristics of the polyimide film according to the present invention.

This will be described in more detail later, but it seems to be due to the inclusion of a non-polar portion in the molecular structure of the polyimide film according to the present invention.

As described above, the polyimide film according to the present invention satisfies all of the above conditions, so it can be used as an insulating film for flexible metal clad laminates, and insulation stability can be secured even at high frequencies, and signal transmission delay is minimized can do.

In the present invention, the preparation of the polyamic acid is, for example,

(1) a method in which the whole amount of the diamine component is placed in a solvent, and then the dianhydride component is added so as to be substantially equimolar with the diamine component, followed by polymerization;

(2) a method in which the entire amount of the dianhydride component is placed in a solvent, and then the diamine component is added so as to be substantially equimolar with the dianhydride component and polymerized;

(3) After putting some of the diamine components in the solvent, mixing some of the dianhydride components with respect to the reaction components in a ratio of about 95 to 105 mol%, then adding the remaining diamine components and successively with the remaining dianhydride acid a method of polymerization by adding a component so that the diamine component and the dianhydride component are substantially equimolar;

(4) After putting the dianhydride component in the solvent, mixing some components of the diamine compound in a ratio of 95 to 105 mol% with respect to the reaction component, adding another dianhydride component, and then adding the remaining diamine components, a method of polymerization such that the diamine component and the dianhydride component are substantially equimolar;

(5) reacting some diamine component and some dianhydride component in an excess of any one in a solvent to form a first composition, and reacting some diamine component and some dianhydride component in another solvent so that any one is excessive 2 After forming the composition, the first and second compositions are mixed and polymerization is completed. At this time, when the diamine component is excessive when the first composition is formed, in the second composition, the dianhydride component is used in excess And, when the dianhydride component in the first composition is excessive, in the second composition, the diamine component is in excess, and the first and second compositions are mixed and the total diamine component and the dianhydride component used in these reactions are substantially the same The method of superposing|polymerizing so that it may become molar, etc. are mentioned.

However, the polymerization method is not limited to the above examples, and any known method may be used for the preparation of the first to third polyamic acids.

In one specific example, the method for producing a polyimide film according to the present invention,

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

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

(c) preparing a third polyamic acid by copolymerizing the first polyamic acid and the second polyamic acid in an organic solvent; and

(d) forming a film of the precursor composition including the third polyamic acid on a support, and then imidizing the film may include.

The first dianhydride component and the second dianhydride component may each include at least one selected from the group consisting of biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA).

In addition, the first diamine component and the second diamine component include at least one selected from the group consisting of m-tolidine and paraphenylene diamine (PPD).

Based on 100 mol% of the total content of the first diamine component and the second diamine component, the content of m-tolidine is 30 mol% or more and 50 mol% or less, and the content of paraphenylene diamine is 50 mol% or more 70 mol% or less.

In addition, based on 100 mol% of the total content of the first dianhydride component and the second dianhydride component, the content of the biphenyltetracarboxylic dianhydride is 45 mol% or more and 65 mol% or less, and pyromellitic The content of dianhydride (PMDA) may be 35 mol% or more and 55 mol% or less.

Preferably, the first polyamic acid includes a dianhydride component including biphenyltetracarboxylic dianhydride and a diamine component including m-tolidine and paraphenylene diamine, The second polyamic acid may include a dianhydride component including biphenyltetracarboxylic 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 as a random polymerization method, and the polyimide film prepared from the polyamic acid of the present invention prepared by the above process has a dielectric loss factor (Df) and It can be preferably applied in terms of maximizing the effect of the present invention for lowering moisture absorption and air permeability.

However, in the polymerization method, since the length of the repeating unit in the above-described polymer chain is relatively short, there may be a limit in exhibiting excellent properties of the polyimide chain derived from the dianhydride component. Accordingly, 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 for synthesize|combining a polyamic acid is not specifically limited, Any solvent can be used as long as it is a solvent in which a polyamic acid is dissolved, It is preferable that it is an amide type solvent.

Specifically, the solvent may be an organic polar solvent, specifically an aprotic polar solvent, for example, N,N-dimethylformamide (DMF), N,N- It may be at least one selected from the group consisting of dimethylacetamide, N-methyl-pyrrolidone (NMP), gamma butyrolactone (GBL), and Diglyme, but is not limited thereto. It can be used in combination of 2 or more types.

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

In addition, in the polyamic acid manufacturing process, a filler may be added for the purpose of improving 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, but preferred examples thereof 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, and may be determined according to the characteristics of the film 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.

When the particle size is less than this range, the modifying effect becomes difficult to appear, and when the particle size exceeds this range, the surface properties may be greatly impaired or the mechanical properties may be greatly reduced.

Moreover, it is not specifically limited also about the addition amount of a filler, What is necessary is just to determine by the film characteristic to be modified|reformed, a filler particle diameter, etc. In general, the added amount of the filler is 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, and more preferably 0.02 to 80 parts by weight based on 100 parts by weight of polyimide.

When the filler addition amount is less than this range, the modifying effect by the filler is difficult to appear, and when it exceeds this range, the mechanical properties of the film may be greatly impaired. The method of adding a filler is not specifically limited, Any well-known method can also be used.

In the manufacturing method of the present invention, the polyimide film may be prepared by thermal imidization and chemical imidization.

Also, it may be prepared by a complex imidization method in which thermal imidization and chemical imidization are combined.

The thermal imidization method is a method in which a chemical catalyst is excluded and the imidization reaction is induced by a heat source such as hot air or an infrared dryer.

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

However, in the process of forming the gel film, some of the amic acid (about 0.1 mol% to 10 mol%) may be imidized, and for this purpose, the polyamic acid composition is dried at a variable temperature in the range of 50 ℃ to 200 ℃. and may also be included in the scope of the thermal imidization method.

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

As an example of the complex imidization method, after adding a dehydrating agent and an imidizing agent to a polyamic acid solution, heating at 80 to 200° C., preferably 100 to 180° C., partially curing and drying, at 200 to 400° C. 5 to 400 By heating for a second, a polyimide film can be manufactured.

The polyimide film of the present invention manufactured according to the above manufacturing method may have a glass transition temperature (Tg) of 320° C. or higher, a moisture absorption rate of 0.4% or lower, and a dielectric loss factor (Df) of 0.004 or lower.

The present invention provides a multilayer film including the above-described polyimide film and a thermoplastic resin layer, and a flexible metal clad laminate including the above-described polyimide film and an electrically conductive metal foil.

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

The metal foil to be used is not particularly limited, but when the flexible metal foil laminate of the present invention is used for electronic devices or electrical devices, for example, copper or copper alloy, stainless steel or its alloy, nickel or nickel alloy (42 alloy). Also included), it may be a metal foil comprising aluminum or an aluminum alloy.

In general flexible metal clad laminates, copper foils such as rolled copper foils and electrolytic copper foils are often used, and they can be preferably used in the present invention as well. Moreover, the antirust layer, the heat-resistant layer, or the adhesive layer may be apply|coated on the surface of these metal foils.

In the present invention, the thickness of the metal foil is not particularly limited, and may have a thickness capable of exhibiting a sufficient function according to its use.

In the flexible metal clad laminate according to the present invention, a metal foil is laminated on one surface of the polyimide film, or an adhesive layer containing a thermoplastic polyimide is added to one surface of the polyimide film, and the metal foil is attached to the adhesive layer. It may have a laminated structure.

The present invention also provides an electronic component including the flexible metal clad laminate as an electrical signal transmission circuit. The electrical signal transmission circuit may be an electronic component that transmits a signal at a high frequency of at least 2 GHz, specifically, a high frequency of at least 5 GHz, and more specifically, 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 aerospace, but is not limited thereto.

Hereinafter, through specific examples of the invention, the operation and effect of the invention will be described in more detail. However, these embodiments are merely presented as an example of the invention, and the scope of the invention is not defined thereby.

<Example 1>

DMF was introduced while nitrogen was injected into a 500 ml reactor equipped with a stirrer and nitrogen injection and discharge tube, and the temperature of the reactor was set to 30 ° C. As a diamine component, m-tolidine and paraphenylene diamine; Biphenyltetracarboxylic dianhydride is added as a dianhydride component to confirm that it is completely dissolved. A first polyamic acid having a viscosity of 200,000 cP at 23°C was prepared after stirring was continued for 120 minutes while heating and raising the temperature to 40°C in a nitrogen atmosphere.

NMP was introduced while nitrogen was injected into a 500 ml reactor equipped with a stirrer and nitrogen injection/discharge tube, and the temperature of the reactor was set to 30° C., m-tolidine as a diamine component, and biphenyltetracarboxylic dian Confirm that the hydride and pyromellitic dianhydride are completely dissolved. A second polyamic acid having a viscosity of 200,000 cP at 23°C was prepared after stirring was continued for 120 minutes while heating and raising the temperature to 40°C in a nitrogen atmosphere.

Then, the temperature of the first polyamic acid and the second polyamic acid was raised to 40° C. under a nitrogen atmosphere and stirring was continued for 120 minutes while heating, the final viscosity at 23° C. was 200,000 cP, and the diamine component and dianhydride acid A third polyamic acid including the components as shown in Table 1 was prepared.

The third polyamic acid prepared above was bubbled through a high-speed rotation of 1,500 rpm or more. Thereafter, the polyamic acid and the catalyst are mixed and mixed, followed by film casting, and dried under a nitrogen atmosphere and at a temperature of 90-200° C. for 30 minutes to prepare a gel film, and the gel film is heated to 450° C. at a rate of 2° C./min. The temperature was raised, heat treatment was performed at 450° C. for 60 minutes, and cooling was performed to 30° C. at a rate of 2° C./min to obtain a polyimide film.

Thereafter, the polyimide film was peeled off the glass substrate by dipping in distilled water. The thickness of the prepared polyimide film was 15 μm. The thickness of the prepared polyimide film was measured using an Anritsu film thickness tester (Electric Film thickness tester).

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

In Example 1, a polyimide film was prepared in the same manner as in Example 1, except that the components and their contents were respectively changed as shown in Table 1 below.

	Dianhydride component (mol%)		Diamine component (mol%)		Polyamic acid polymerization method
	BPDA (mol%)	PMDA (mol%)	m-Tolidine (mol%)	PPD (mol%)
Example 1	55	45	40	60	block polymerization
Example 2	60	40	46	54	block polymerization
Example 3	60	40	34	66	block polymerization
Example 4	48	52	46	54	block polymerization
Comparative Example 1	40	60	90	10	block polymerization
Comparative Example 2	50	50	60	40	block polymerization
Comparative Example 3	40	60	100	-	block polymerization
Comparative Example 4	60	40	100	-	block polymerization
Comparative Example 5	50	50	50	50	block polymerization

Experimental example

For the polyimide films prepared in Examples 1 to 4 and Comparative Examples 1 to 5, respectively, moisture permeability, dielectric loss rate, thermal properties (coefficient of thermal expansion and glass transition temperature) and film formation properties were evaluated, and the results were evaluated. It is shown in Table 2 below.

(1) moisture permeability

Moisture permeability was measured using a Permatran-W 3/33 MA instrument at 38±2°C, 100% R.H. (Measurement standards are in accordance with ASTM F1249).

(2) Measurement of dielectric loss factor

The dielectric loss factor (Df) was measured by leaving the flexible metal clad laminate for 72 hours using an Agilent 4294A ohmmeter.

(3) Measurement of coefficient of thermal expansion

The coefficient of thermal expansion (CTE) was measured using a Q400 thermomechanical analyzer from TA, and after cutting a polyimide film to 4 mm in width and 20 mm in length, while applying a tension of 0.05 N under a nitrogen atmosphere, 10 °C/min After raising the temperature from room temperature to 300°C at a rate of

(4) Glass transition temperature measurement

The glass transition temperature (T _g ) was obtained by obtaining the loss modulus and storage modulus of each film using DMA, and the inflection point was measured as the glass transition temperature in their tangent graph.

(5) Filmization characteristics (flatness evaluation)

Filming properties were evaluated by visually observing the presence or absence of wrinkles in the polyimide films prepared in Examples and Comparative Examples. The results are shown in Table 2 below.

<Evaluation criteria>

○: film flatness is constant without wrinkling

X: The flatness of the film is not uniform due to the influx of wrinkles

	unit thickness moisture permeability (g/(m 2 *day))/㎛)	dielectric properties (23℃/50RH%)	thermal properties		Filmization properties
		Df	CTE (ppm/℃)	Tg(℃)
Example 1	0.010	0.0028	15	310	O
Example 2	0.013	0.0027	17	306	O
Example 3	0.012	0.0028	16	310	O
Example 4	0.014	0.0029	18	305	O
Comparative Example 1	0.05	0.0035	12	305	O
Comparative Example 2	not measurable	0.0027	not measurable	296	X
Comparative Example 3	0.042	0.0039	6	305	O
Comparative Example 4	0.018	0.0045	12	285	X
Comparative Example 5	0.072	0.0034	8	335	O

As can be seen in Table 2, it can be confirmed that the polyimide film prepared according to the embodiment of the present invention exhibits a remarkably low dielectric loss factor of 0.003 or less, and the glass transition temperature is at a desired level. In addition, it was confirmed that the moisture permeability also showed excellent results, and it was found that the filmization was well implemented because it had excellent flatness because wrinkles did not occur. These results are achieved by the components and composition ratios specified herein, and it can be seen that the content of each component plays a decisive role. On the other hand, the polyimide films of Comparative Examples 1 to 5 had a high dielectric loss factor or Not only the glass transition temperature was measured to be low, but also the water permeability was lowered compared to the Example. In addition, in the case of Comparative Examples 2 and 4, it can be seen that the filmization is not realized because the flatness of the film is not constant due to the inflow of wrinkles. From this, it can be expected that the comparative examples are difficult to be used in electronic components in which signals are transmitted at high frequencies in the unit of gigabytes.

Although described above with reference to the embodiments of the present invention, those of ordinary skill 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 content.

The polyimide film according to the embodiment of the present invention can have low dielectric properties and high heat resistance properties by minimizing moisture absorption and air permeability by using a specific dianhydride component and a specific diamine component in a specific molar ratio in combination.

In addition, the present invention can implement high-speed communication at a high frequency of 10 GHz or more, including the polyimide film as described above, and thus can be usefully applied to electronic components such as flexible metal clad laminates.

Claims (14)

1. dianhydride components including biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA); and

   It is prepared by imidizing a polyamic acid solution containing a diamine component including m-tolidine and paraphenylene diamine (PPD),

   Based on 100 mol% of the total content of the diamine component, the content of m-tolidine is 30 mol% or more and 50 mol% or less, and the content of paraphenylene diamine is 50 mol% or more and 70 mol% or less, polyimide film.
2. According to claim 1,

   Based on 100 mol% of the total content of the dianhydride component, the content of the biphenyltetracarboxylic dianhydride is 45 mol% or more and 65 mol% or less, and the content of pyromellitic dianhydride is 35 mol% or more and 55 % by mole or less, a polyimide film.
3. According to claim 1,

   A polyimide film comprising a block copolymer consisting of two or more blocks.
4. According to claim 1,

   a first block obtained by imidizing a dianhydride component containing biphenyltetracarboxylic dianhydride and a diamine component containing m-tolidine and paraphenylene diamine; and

   A second block obtained by imidizing a dianhydride component containing biphenyltetracarboxylic dianhydride and pyromellitic dianhydride and a diamine component containing m-tolidine which is a polyimide film.
5. According to claim 1,

   A glass transition temperature (Tg) of 300° C. or higher, and a dielectric loss factor (Df) of 0.003 or less, a polyimide film.
6. According to claim 1,

   A polyimide film having a moisture permeability of 0.02 (g/(m ² *day))/μm) or less.
7. According to claim 1,

   A polyimide film having a coefficient of thermal expansion of 15 to 18 ppm/°C.
8. (a) preparing a first polyamic acid by polymerizing the first dianhydride component and the first diamine component in an organic solvent;

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

   (c) preparing a third polyamic acid by copolymerizing the first polyamic acid and the second polyamic acid in an organic solvent; and

   (d) forming a film of the precursor composition including the third polyamic acid on a support, and then imidizing;

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

   The first diamine component and the second diamine component each include at least one selected from the group consisting of m-tolidine and paraphenylene diamine (PPD),

   Based on 100 mol% of the total content of the first diamine component and the second diamine component, the content of m-tolidine is 30 mol% or more and 50 mol% or less, and the content of paraphenylene diamine is 50 mol% or more 70 mol% or less, a method for producing a polyimide film.
9. 9. The method of claim 8,

   Based on 100 mol% of the total content of the first dianhydride component and the second dianhydride component, the content of the biphenyltetracarboxylic dianhydride is 45 mol% or more and 65 mol% or less, and pyromellitic dianhydride A method for producing a polyimide film, wherein the content of the Ride (PMDA) is 35 mol% or more and 55 mol% or less.
10. 9. The method of claim 8,

    The first polyamic acid includes a dianhydride component including biphenyltetracarboxylic dianhydride and a diamine component including m-tolidine and paraphenylene diamine,

    The second polyamic acid comprises a dianhydride component including biphenyltetracarboxylic dianhydride and pyromellitic dianhydride and a diamine component including m-tolidine.
11. 9. The method of claim 8,

    A method for producing a polyimide film, wherein the glass transition temperature (Tg) of the prepared polyimide film is 300° C. or more, and the dielectric loss factor (Df) is 0.003 or less.
12. A multilayer film comprising the polyimide film according to claim 1 and a thermoplastic resin layer.
13. A flexible metal clad laminate comprising the polyimide film according to claim 1 and an electrically conductive metal foil.
14. An electronic component comprising the flexible metal clad laminate according to claim 13 .