KR20220044928A - High Modulus Polyimide Film And Flexible Metal Foil Clad Laminate Comprising the Same - Google Patents

Abstract

The present invention provides a polyimide film prepared by imidizing a polyamic acid prepared by combining a diamine monomer containing a diamine represented by chemical formula 1 and a dianhydride monomer containing pyromellitic dianhydride (PMDA). The polyimide film has a modulus at 25℃ of greater than 6.5 Gpa and a coefficient of thermal expansion (CTE) of -5 to 13 ppm/℃. The polyimide film can exhibit excellent mechanical properties such as elastic modulus and chemical resistance as well as low moisture absorption, dielectric constant, and dielectric loss.

Description

High Modulus Polyimide Film And Flexible Metal Foil Clad Laminate Comprising the Same}

The present invention relates to a highly elastic polyimide film and a flexible metal clad laminate comprising the same.

Polyimide (PI) is a polymer 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. is the material Accordingly, polyimide is in the spotlight as an insulating material for microelectronic components that strongly require the above-mentioned properties.

Examples of microelectronic components include thin circuit boards that have high circuit integration and are flexible in order to cope with weight reduction and miniaturization of electronic products, and the polyimide is widely used as an insulating film for thin circuit boards.

For reference, the thin circuit board generally has a structure in which a circuit including a metal foil is formed on a polyimide film, and such a thin circuit board is also referred to as a flexible metal foil clad laminate in a broad sense.

The polyimide film applied to the flexible metal clad laminate as described above requires excellent mechanical properties and chemical resistance, in particular, a low coefficient of thermal expansion and a high modulus of elasticity.

In order to obtain a polyimide film having such properties, it is generally known to use a monomer having a relatively rigid structure, that is, a monomer having high polymer chain linearity. , rather, the flexibility of the polyimide film is lowered, and in some cases, filming itself may be impossible.

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.

In order to realize high-frequency and high-speed communication, an insulator having a high impedance capable of maintaining electrical insulation even at a high frequency is required. Impedance is inversely proportional to the frequency and dielectric constant (Dk) formed in the insulator. In order to maintain insulation even at high frequencies, the dielectric constant must be as low as possible.

However, in the case of conventional polyimide, the dielectric constant is about 3.4 to 3.6, which is not excellent enough to maintain sufficient insulation in high-frequency communication. Or there is a possibility of total loss.

In addition, as the dielectric constant of the insulator is lower, the occurrence of undesirable stray capacitance and noise in the thin circuit board can be reduced, and it is known that the cause of communication delay can be largely resolved. It is recognized that making the dielectric constant of the thin circuit board as low as possible is the most important factor in the performance of the thin circuit board.

Another thing to note is that, in the case of high-frequency communication of 2 GHz or higher, dielectric dissipation occurs inevitably through polyimide. Dielectric dissipation factor (Df) refers to the degree of wastage of electrical energy in a thin circuit board, and is closely related to the signal propagation delay that determines the communication speed. It is recognized as an important factor in the performance of circuit boards.

As the polymer film contains more moisture, the dielectric constant increases and the dielectric loss factor increases. In the case of polyimide film, it is suitable as a material for thin circuit boards in that it has the highest level of mechanical properties and chemical resistance, but it may be relatively vulnerable to moisture due to polar imide groups, and thus the highest level of insulation properties is not easy to implement.

Therefore, there is a need to develop a polyimide film capable of film formation while maintaining mechanical properties such as elastic modulus and chemical resistance at the highest level, and having a relatively low dielectric constant and dielectric loss factor.

It is an object of the present invention to provide a polyimide film having excellent mechanical properties such as elastic modulus and chemical resistance, and having relatively low dielectric constant and dielectric loss factor, and a flexible metal clad laminate including the same.

According to an aspect of the present invention, a polyamic acid is prepared by combining a diamine monomer containing a diamine represented by a specific chemical formula and a dianhydride monomer containing pyromellitic dianhydride (PMDA), and imidizing it. The polyimide film to be used has excellent mechanical properties such as elastic modulus and chemical resistance, and at the same time can exhibit low moisture absorption, dielectric constant, and dielectric loss rate.

According to another aspect, the flexible metal clad laminate including the polyimide film is implemented as a circuit capable of high-speed communication at a high frequency based on the high elastic modulus, relatively low moisture absorption, dielectric constant and dielectric loss factor of the polyimide film. can be

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

In order to achieve the above object, the present invention,

a diamine monomer comprising a diamine represented by the following formula (1); and

It is prepared by imidizing a polyamic acid derived from polymerization of a dianhydride monomer including pyromellitic dianhydride (PMDA),

Provided is a polyimide film having a modulus at 25°C of 6.5 Gpa or more and a coefficient of thermal expansion (CTE) of -5 to 13 ppm/°C.

(1)

(One)

In Formula 1, R1 and R2 are each independently a C ₁ -C ₆ alkyl group or a C ₁ -C ₆ alkoxy group.

In the case of the polyimide film according to the present invention, it has a relatively low moisture absorption, dielectric constant and dielectric loss while having an excellent elastic modulus, so that it can be preferably applied to a circuit capable of high-speed communication at a high frequency.

Accordingly, specific details for its implementation will be described herein.

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.

As used herein, "dianhydride (dianhydride)" is intended to include its precursors or derivatives, which may not technically be dianhydrides, but nevertheless react with diamines to form polyamic acids. and this polyamic acid can be converted back to polyimide.

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 to mid.

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, unless otherwise stated, the range is intended to include the endpoint and all integers and fractions within the range.

It is intended that the scope of the invention not be limited to the particular values recited when defining the ranges.

First aspect: polyimide film

The polyimide film according to the present invention comprises:

a diamine monomer comprising a diamine represented by the following formula (1); and

It is prepared by imidizing a polyamic acid derived from polymerization of a dianhydride monomer including pyromellitic dianhydride (PMDA),

It is characterized in that the modulus at 25°C is 6.5 Gpa or more, and the coefficient of thermal expansion (CTE) is -5 to 13 ppm/°C.

(1)

(One)

In Formula 1, R1 and R2 are each independently a C ₁ -C ₆ alkyl group or a C ₁ -C ₆ alkoxy group.

Therefore, the polyimide film according to the present invention exhibits excellent mechanical properties as the modulus and the coefficient of thermal expansion satisfy the above ranges, and can effectively suppress dimensional changes occurring when the flexible copper clad laminate is manufactured.

In order to suppress thermal distortion that may occur when laminating the polyimide film and the metal foil, it is most ideal that the thermal expansion coefficients of the polyimide film and the metal foil are the same in the temperature range of 300 to 350°C. However, since it is not practically easy to set the coefficient of thermal expansion of the polyimide film to be exactly the same as that of the metal foil, from the practical point of view of suppressing the occurrence of thermal distortion, the difference between the coefficient of thermal expansion of the polyimide film and the metal foil is within ±10 ppm, detailed It is preferable to be within ±5 ppm.

In addition, since an adhesive layer having adhesive properties may be formed between the polyimide film and the metal foil, the difference from the coefficient of thermal expansion of the adhesive layer should also be considered. When it has a coefficient of thermal expansion of -5 to 13 ppm/°C at 300 to 350°C, the dimensional change of the manufactured flexible metal clad laminate can be minimal, and when it is out of this, the appearance due to the difference in the degree of expansion in the MD and TD directions defects may be caused. More preferably, the coefficient of thermal expansion may be -5 to 5 ppm/℃.

On the other hand, permittivity is an important characteristic value indicating the electrical characteristics of a dielectric (or insulator), that is, an insulator. It is known that there is

In an insulator (eg, polyimide film), + and - moment components, which are normally scattered in random directions, are aligned according to the change in alternating current of an externally applied electromagnetic field. That is, as the moment components change according to the change direction of the electromagnetic field, it is possible to enable the propagation of electromagnetic waves to the other side even though it is an insulator.

The degree of how sensitively the moment inside the material responds to such a change in the external electromagnetic field and moves can be expressed as the permittivity.

In general, this permittivity allows intuitive interpretation through relative permittivity. The relative permittivity refers to the permittivity of each dielectric in proportion to air as 1, and among them, an imaginary number is Excluded and expressed as a real number is the dielectric constant (Dk).

Since a high dielectric constant means that electric energy is transmitted well, an insulator such as a polyimide film has a lower dielectric constant, which is preferable.

Nevertheless, it has already been described that a typical polyimide film is not at a level sufficient to maintain sufficient insulation in high-frequency communication. This becomes clear when compared with the dielectric constant of liquid crystal polymers. In the case of liquid crystal polymers, the dielectric constant is known to be approximately 2.9 to 3.3, and most of them are superior as insulators compared to conventional polyimides having a dielectric constant higher than that of polyimide. can see.

On the other hand, the polyimide film according to the present invention may have a dielectric constant close to or lower than that of the liquid crystal polymer, specifically 3.5 or less, and the lower limit thereof may be at least 2.8. It can be seen that this is an ideal shape as an insulator, considering that the engineering properties of the polyimide film are at the highest level.

The meaning of these dielectric constants will be described in detail.

Even if all conductors are separated from each other, capacitive coupling by an electric field always exists between them. It can be seen that a capacitor of a certain value is connected between them.

On the other hand, as the frequency of the current or voltage across the capacitor increases, the impedance of the capacitor decreases, and the value can be expressed as the following equation.

-Impedance = 1/(2*π*f*C); where f is the frequency and C = capacitance.

-C = e*S/d; where e is the dielectric constant, S is the area of the conductor, and d is the distance.

In general, on a scale that can be seen and handled with bare hands, it is difficult for the capacitance value (farad) between the two conductors to exceed the pico unit no matter how close the two conductors are brought. It is so small that even if the circuit operates at a somewhat high frequency, the insulation between the layers can be maintained well.

On the other hand, in special cases such as communication equipment operating at a frequency of giga (GIGA) units, for example, 2 GHz or higher, insulation may be difficult to maintain because the frequency is so high that the impedance is lowered as in the above equation.

Therefore, when selecting an insulator, it is necessary to minimize electrostatic coupling and capacitance (ie, impedance) by using a material with as low a dielectric constant as possible.

Accordingly, the polyimide film according to the present invention has a relatively low dielectric constant as described above, so it is easy to maintain insulation even in communication equipment operating at a frequency of giga (GIGA) units, for example, a very high frequency of 2 GHz or more. There is one advantage.

Next, “dielectric loss factor” refers to the force dissipated by a dielectric (or insulator) when friction of molecules interferes with molecular motion caused by alternating electric fields.

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 a strong requirement for the polyimide film, which is an insulating film. The polyimide film according to the present invention may have a dielectric loss factor of 0.006 or less, specifically 0.005 or less, and more specifically 0.004 or less, under a fairly high frequency of about 2 GHz. there is.

On the other hand, the moisture absorption rate is a ratio indicating the amount of moisture absorbed by a material, and it is generally known that when the moisture absorption rate is high, the dielectric constant and the dielectric loss rate increase.

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.

That is, water existing in a water vapor state outside the polyimide film does not substantially affect the dielectric constant and dielectric loss factor of the polyimide film. However, when water vapor or the like is absorbed into the polyimide film, water exists in a liquid state. In this case, the dielectric constant and dielectric loss factor of the polyimide film may dramatically increase.

That is, the dielectric constant and dielectric loss factor of the polyimide film may change rapidly with only a small amount of moisture absorption. Therefore, making the moisture absorption rate low can be seen as a very important factor for the polyimide film as an insulating film.

The polyimide film according to the present invention may have a moisture absorption of less than 1.0% by weight, specifically 0.8% by weight or less, and more specifically 0.6% by weight or less, and achieving this is a structural characteristic of the polyimide film according to the present invention. is due to

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

As an embodiment of the present invention for a polyimide film having the above conditions, a diamine monomer, a dianhydride monomer, and a blending ratio thereof will be described in detail through the following non-limiting examples.

In one specific example, the dianhydride monomer may include pyromellitic dianhydride (PMDA). PMDA is a monomer having a relatively rigid structure among dianhydride monomers, and can provide excellent elasticity to a polyimide film prepared including the same. The polyimide film can exhibit a more excellent modulus of elasticity due to structural factors unique to the polyimide chain.

Specifically, the polyimide chain derived from the PMDA and the diamine of Formula 1 has a structure named as a charge transfer complex (CTC), that is, an electron donor and an electron acceptor are close to each other. It has a regular structure in which it is positioned, and due to this structure, the intermolecular secondary bonding force is strengthened, thereby exhibiting a high modulus of elasticity.

In addition, in one specific example, the dianhydride monomer may further include BPDA together with the PMDA. In this case, the polyimide chain derived from the BPDA and the diamine of Formula 1 also has the CTC structure described above, and since this structure has an effect of preventing hydrogen bonding with moisture, the moisture absorption rate of the polyimide film can be lowered. In particular, the hydrophobicity of the aliphatic moiety included in the diamine represented by Chemical Formula 1 is added, so that the effect of lowering the moisture absorption of the polyimide film can be expected.

However, in order for the polyimide film to exhibit an excellent elastic modulus and at the same time satisfy a low moisture absorption rate, the content ratio of PMDA and BPDA included as a dianhydride monomer is particularly important. For example, as the content ratio of BPDA becomes relatively small, it is difficult to expect a low moisture absorption rate due to the CTC structure.

This is because BPDA contains two benzene rings corresponding to the aromatic moiety, whereas PMDA contains one benzene ring corresponding to the aromatic moiety. It can be understood that the imide group in the polyimide polymer chain increases, and it can be understood that the ratio of the imide group derived from PMDA in the polyimide polymer chain is relatively increased compared to the imide group derived from BPDA.

That is, the increase in the content of PMDA can be seen as a relative increase in the imide group in the entire polyimide film, and thus it is difficult to expect a low moisture absorption rate. Conversely, a decrease in the content of PMDA results in a decrease in the dianhydride monomer having a relatively rigid structure, and thus the elastic modulus of the polyimide film may not achieve a desired level.

For this reason, in the present invention, when the BPDA is included as a diamine monomer, the molar ratio of PMDA to BPDA is 4:6 to 8:2, specifically 6:4 to 8:2.

In addition, the dianhydride monomer contains 40 mol% to 80 mol% of PMDA, specifically 60 mol% to 80 mol%, and 20 mol% to 60 mol% of BPDA based on the total number of moles thereof. can

When the content of PMDA exceeds the above range or the content of BPDA is below the above range, it is not preferable because it is difficult to achieve desired levels of dielectric constant, dielectric loss rate, and moisture absorption rate. On the contrary, when the content of PMDA is lower than the above range or the content of BPDA is higher than the above range, mechanical properties such as elastic modulus of the polyimide film to be manufactured are reduced, and suitable for manufacturing a flexible metal clad laminate It is not preferable because the level of heat resistance cannot be ensured.

In one specific example, the diamine monomer may include a diamine represented by Formula 1 below.

(1)

(One)

In Formula 1, R1 and R2 are each independently a C ₁ -C ₆ alkyl group or a C ₁ -C ₆ alkoxy group.

In this case, when R1 and R2 are methyl groups, Formula 1 may be m-Tolidine.

In one specific example, the diamine monomer may include 80 mol% to 100 mol%, specifically, 90 mol% to 100 mol%, of the diamine represented by Formula 1 based on the total number of moles thereof.

In this case, when the content of the diamine of Formula 1 is less than 100 mol%, the diamine monomer may include the diamine classified as follows along with the diamine of Formula 1 above.

1) 1,4-diaminobenzene (or paraphenylenediamine, PPD), 1,3-diaminobenzene, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzo A diamine having a single benzene nucleus in structure, such as acid acid (or DABA), and a diamine having a relatively rigid structure;

2) 4,4'-diaminodiphenyl ether (or oxydianiline, ODA), diaminodiphenyl ether such as 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl ) -4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane , 3,3',5,5'-tetramethyl-4,4'-diaminodiphenylmethane, bis(4-aminophenyl)sulfide, 4,4'-diaminobenzanilide, 3,3' -dichlorobenzidine, 3,3'-dimethylbenzidine (or o-tolidine), 2,2'-dimethylbenzidine (or m-tolidine), 3,3'-dimethoxybenzidine, 2,2'-dimethoxy Benzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4' -diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone , 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'-diamino-4,4'-dichlorobenzophenone, 3,3'-diamino-4,4' -dimethoxybenzophenone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis (3- aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane; 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenylsulfoxide, 3,4'-diaminodi diamines having two benzene nuclei in structure, such as phenylsulfoxide and 4,4'-diaminodiphenylsulfoxide;

3) 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-amino) Phenyl)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene (or TPE-Q), 1,4-bis(4-aminophenoxy) Benzene (or TPE-Q), 1,3-bis (3-aminophenoxy) -4-trifluoromethylbenzene, 3,3'-diamino-4- (4-phenyl) phenoxybenzophenone, 3 ,3'-diamino-4,4'-di(4-phenylphenoxy)benzophenone, 1,3-bis(3-aminophenylsulfide)benzene, 1,3-bis(4-aminophenylsulfide) Benzene, 1,4-bis(4-aminophenylsulfide)benzene, 1,3-bis(3-aminophenylsulfone)benzene, 1,3-bis(4-aminophenylsulfone)benzene, 1,4-bis( 4-aminophenylsulfone)benzene, 1,3-bis[2-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(3-aminophenyl)isopropyl]benzene, 1,4- diamines having three benzene nuclei in the structure, such as bis[2-(4-aminophenyl)isopropyl]benzene;

4) 3,3'-bis(3-aminophenoxy)biphenyl, 3,3'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(3-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)biphenyl, bis[3-(3-aminophenoxy)phenyl]ether, bis[3-(4-aminophenoxy)phenyl]ether, bis[4- (3-aminophenoxy)phenyl]ether, bis[4-(4-aminophenoxy)phenyl]ether, bis[3-(3-aminophenoxy)phenyl]ketone, bis[3-(4-aminophenoxy) cy)phenyl]ketone, bis[4-(3-aminophenoxy)phenyl]ketone, bis[4-(4-aminophenoxy)phenyl]ketone, bis[3-(3-aminophenoxy)phenyl]sulfide , bis[3-(4-aminophenoxy)phenyl]sulfide, bis[4-(3-aminophenoxy)phenyl]sulfide, bis[4-(4-aminophenoxy)phenyl]sulfide, bis[3- (3-aminophenoxy)phenyl]sulfone, bis[3-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy) cy)phenyl]sulfone, bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl ]methane, bis[4-(4-aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-(4 -aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane ( BAPP), 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [3- (4- Aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3 structure, such as ,3,3-hexafluoropropane, 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, etc. Diamine with 4 phase benzene nuclei.

These may be used alone or in combination of two or more types together with the diamine represented by the above formula (1), as desired, but diamines that can be particularly preferably used in the present invention include 1,4-phenylenediamine (PPD) It may be at least one selected from 4,4'-oxydianiline (ODA).

The polyimide film according to the present invention may be prepared by imidization of polyamic acid derived from polymerization of the diamine monomer and dianhydride monomer, and the polyimide polymer chain formed by imidization of the polyamic acid is represented by Formula 1 It may contain an aliphatic moiety derived from R1 and R2 of the diamine represented.

In the present invention, the diamine included in the diamine monomer may be appropriately selected depending on a desired level of heat resistance or mechanical properties, but may contain a certain amount or more of the diamine including an aliphatic moiety as described above, and is represented by Formula 1 When the content of the diamine is less than the above range, it is not preferable because a low moisture absorption at a desired level cannot be achieved.

Specifically, the aliphatic moiety may be selected to have non-polarity, and for example, R1 and R2 may be an alkyl group having non-polarity while excluding excessive occupation of the molecular weight of the aliphatic moiety, specifically, R1 and R2 Each may be a methyl group.

That is, when the aliphatic moiety is included in the polyamic acid, the relative ratio of amic acid groups that significantly affect the increase in hygroscopicity compared to the aliphatic moiety in the entire polyamic acid may be lowered. Therefore, it can act positively to lower the hygroscopicity of the polyimide film prepared from such polyamic acid.

Since it has already been explained that the dielectric constant and the dielectric loss factor are closely related, in summary, the aliphatic moiety derived from R1 and R2 can be understood as a major factor that allows the polyimide film according to the present invention to have a low dielectric constant and a low dielectric loss factor. will be.

In order to achieve the desired dielectric constant, dielectric loss rate, and moisture absorption rate as described above, the molecular weight of the aliphatic moiety may be 4 to 25% based on the total molecular weight of one polyimide polymer chain, specifically 6 to 17 It can be %.

When the molecular weight of the aliphatic moiety exceeds the above range, the mechanical properties of the polyimide film are lowered, and it is difficult to achieve an appropriate level of heat resistance for manufacturing a flexible metal clad laminate. It is difficult to achieve a dielectric loss factor and a moisture absorption rate, which is not preferable.

Meanwhile, the polyimide polymer chain formed by imidization of the polyamic acid may include a repeating unit represented by the following Chemical Formula 2 in one polymer chain.

(2)

(2)

In Formula 2, R1 and R2 are each independently a C ₁ -C ₆ alkyl group, or a C ₁ -C ₆ alkoxy group,

Each of n may be an integer of 10 or more.

When n in Formula 2 is an integer of 10 or more, the polyimide film prepared from the polyamic acid may secure an excellent modulus of elasticity of the polyimide chain derived from BPDA and the diamine monomer represented by Formula 1 above.

Conversely, when n is an integer less than 10, that is, when the length of the repeating unit of Formula 2 is too short, there may be a limit to exhibiting mechanical properties such as elastic modulus to a certain level or more.

Considering this, as will be described below, the physical properties of the polyimide film, for example, dielectric constant, dielectric loss rate, moisture absorption rate, by adjusting the length of the repeating unit included in the polyimide chain according to the specific polymerization method of the polyamic acid. , glass transition temperature, coefficient of thermal expansion and modulus can be more precisely controlled.

Second aspect: method for producing polyimide film

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

(1) a method in which the whole amount of the diamine monomer is put in a solvent, and then the dianhydride monomer is added so as to be substantially equimolar with the diamine monomer and polymerized;

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

(3) After some components of the diamine monomer are put in the solvent, some components of the dianhydride monomer are mixed in a ratio of about 95 to 105 mol% with respect to the reaction component, and then the remaining diamine monomer components are added and the remaining components are continuously added thereto. a method of polymerization by adding a dianhydride monomer component so that the diamine monomer and the dianhydride monomer are substantially equimolar;

(4) After the dianhydride monomer is put in the solvent, some components of the diamine compound are mixed in a ratio of 95 to 105 mol% with respect to the reaction component, then another dianhydride monomer component is added and the remaining diamine monomer components are continued. a method of polymerization by adding a diamine monomer and a dianhydride monomer to be substantially equimolar;

(5) reacting some diamine monomer components and some dianhydride monomer components in an excess of any one in a solvent to form a first composition, and mixing some diamine monomer components and some dianhydride monomer components in another solvent A method of forming a second composition by reacting in an excessive amount, then mixing the first and second compositions, and completing polymerization. At this time, when the diamine monomer component is excessive when forming the first composition, the second composition In an excess of the dianhydride monomer component, when the dianhydride monomer component is in excess in the first composition, the diamine monomer component is in excess in the second composition, and the first and second compositions are mixed and used for these reactions and a method of polymerization such that all the diamine monomer components and the dianhydride monomer components used are substantially equimolar.

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) polymerizing PMDA and a diamine monomer in an organic solvent to prepare a first polyamic acid;

(b) copolymerizing a secondary composition comprising at least one selected from the group consisting of a second polyamic acid having a composition different from the first polyamic acid and a monomer for preparing a polyimide and the first polyamic acid to obtain a third polyamic acid manufacturing process; and

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

In the process (a), the diamine monomer is characterized in that it comprises a diamine represented by the following formula (1).

(1)

(One)

In Formula 1, R1 and R2 are each independently a C ₁ -C ₆ alkyl group or a C ₁ -C ₆ alkoxy group.

The second polyamic acid is prepared by polymerizing BPDA and a diamine monomer in an organic solvent, the diamine monomer may include the diamine represented by Chemical Formula 1, and the monomer for preparing the polyimide includes BPDA and a diamine monomer, The diamine monomer may include a diamine represented by Formula 1 above.

In the present invention, the polymerization method of the polyamic acid as described above may be defined as a block polymerization method, for example, by copolymerizing the first polyamic acid and the second polyamic acid in a polymerization state, respectively, and the third polyamic acid A first block polymerization method of producing a mixed acid, a second block polymerization of polymerizing a first polyamic acid, and copolymerizing a second composition in which a monomer for preparing a polyimide is additionally mixed with the first polyamic acid to prepare a third polyamic acid Anticorrosive, a third block polymerization method in which a third polyamic acid is prepared by polymerizing each of the first polyamic acid and a predetermined amount of the second polyamic acid, and then copolymerizing a secondary composition in which a monomer for polyimide production is additionally mixed. can be heard

As described above, the polyimide polymer chain formed by imidization of the third polyamic acid of the present invention polymerized by the above process may include a repeating unit represented by the following Chemical Formula 2 in one polymer chain.

(2)

(2)

In Formula 2, R1 and R2 are each independently a C ₁ -C ₆ alkyl group, or a C ₁ -C ₆ alkoxy group,

Each of n may be an integer of 10 or more.

In Formula 2, when n is an integer of 10 or more, the polyimide film prepared from the polyamic acid can be formed into a film while satisfying excellent mechanical properties including high elasticity, and heat resistance can also be improved.

In a non-limiting example, the polymerization of the polyamic acid of the present invention may include a process of simultaneously adding a diamine monomer including PMDA, BPDA, and a diamine represented by Formula 1, and polymerizing in an organic solvent to prepare a polyamic acid. .

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 constant (Dk), It can be preferably applied in terms of lowering the dielectric loss factor (Df) and moisture absorption.

However, in the polymerization method, since the length of the repeating unit in the polymer chain described above is relatively short, there may be a limit in exhibiting excellent properties of the polyimide chain derived from PMDA and the diamine represented by Formula 1 above. Accordingly, the polymerization method of the polyamic acid that can be particularly preferably used in the present invention may be the 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 through thermal imidization, and chemical imidization may also be performed in parallel.

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 may include the step (c), in which the gel film is heat treated at a variable temperature in the range of 100 to 600 ° C. The amic acid group present in the gel film may be imidized by heat treatment at 200 to 500 °C, more specifically, at 300 to 500 °C.

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

When the chemical imidization method is concurrently used, a polyimide film may be prepared by using a dehydrating agent and an imidizing agent according to a method known in the art.

The polyimide film of the present invention prepared according to the above manufacturing method has a coefficient of thermal expansion of -5 to 13 ppm/℃, a modulus of 6.5 GPa or more, a dielectric constant (Dk) of 3.5 or less, and a dielectric loss factor (Df) is 0.006 or less, the moisture absorption is less than 1.0% by weight, and the glass transition temperature (Tg) may be 280 ℃ or more. Specifically, the coefficient of thermal expansion may be -5 to 5 ppm/℃, and the modulus may be 12.0 GPa or more.

Third aspect: flexible copper clad laminate

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

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), 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.

As described above, the present invention has excellent mechanical properties such as elastic modulus and chemical resistance due to the combination of a specific diamine monomer and a dianhydride monomer and a specific mixing ratio thereof, and at the same time, low moisture absorption, dielectric constant and dielectric loss rate. The branch can provide a polyimide film.

The present invention can also provide a flexible metal clad laminate that can be utilized as an electrical transmission circuit capable of high-frequency communication of 2 GHz or more by including the polyimide film as described above.

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>

NMP was added while injecting nitrogen 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. Then, m-Tolidine as a diamine monomer and PMDA as a dianhydride monomer were added to completely dissolved confirmed that. 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 added while injecting nitrogen into a 500 ml reactor equipped with a stirrer and nitrogen inlet/discharge tube, and the temperature of the reactor was set at 30 ° C. Then, m-Tolidine as a diamine monomer and BPDA as a dianhydride monomer were added confirmed that. 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, and then the final viscosity at 23° C. was 200,000 cP, diamine monomer and dianhydride A third polyamic acid including the Ride monomer 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 defoamed polyimide precursor composition was applied to the glass substrate using a spin coater. Thereafter, the gel film was prepared by drying under a nitrogen atmosphere and at a temperature of 120 ° C. for 30 minutes, and the temperature of the gel film was raised to 450 ° C. A polyimide film was obtained by cooling at a rate of 2° C./min.

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 8 and Comparative Examples 2 to 4>

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

<Comparative Example 1>

NMP was added while injecting nitrogen into a 500 ml reactor equipped with a stirrer and nitrogen inlet/discharge tube, and the temperature of the reactor was set to 30° C. confirmed that. After raising the temperature to 40 °C in a nitrogen atmosphere and stirring for 120 minutes while heating, the viscosity at 23 °C was 200,000 cP, and a polyamic acid containing a diamine monomer and a dianhydride monomer as shown in Table 1 was prepared. .

The polyamic acid prepared above was bubbled through a high-speed rotation of 1,500 rpm or more. Thereafter, the defoamed polyimide precursor composition was applied to the glass substrate using a spin coater. Thereafter, the gel film was prepared by drying under a nitrogen atmosphere and at a temperature of 120 ° C. for 30 minutes, and the temperature of the gel film was raised to 450 ° C. A polyimide film was obtained by cooling at a rate of 2° C./min.

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).

<Comparative Example 5>

NMP was added while injecting nitrogen 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. Then, m-Tolidin as a diamine monomer and BPDA as a dianhydride monomer were added confirmed that. After raising the temperature to 40 °C in a nitrogen atmosphere and stirring for 120 minutes while heating, the viscosity at 23 °C was 200,000 cP, and a polyamic acid containing a diamine monomer and a dianhydride monomer as shown in Table 1 was prepared. .

The polyamic acid prepared above was bubbled through a high-speed rotation of 1,500 rpm or more. Thereafter, the defoamed polyimide precursor composition was applied to the glass substrate using a spin coater. Thereafter, the gel film was prepared by drying under a nitrogen atmosphere and at a temperature of 120 ° C. for 30 minutes, and the temperature of the gel film was raised to 450 ° C. A polyimide film was obtained by cooling at a rate of 2° C./min.

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).

<Example 9>

NMP was added while injecting nitrogen into a 500 ml reactor equipped with a stirrer and nitrogen inlet/discharge tube, and the temperature of the reactor was set to 30° C. It was confirmed that it was dissolved. After raising the temperature to 40 °C in a nitrogen atmosphere and stirring for 120 minutes while heating, the viscosity at 23 °C was 200,000 cP, and a polyamic acid containing a diamine monomer and a dianhydride monomer as shown in Table 1 was prepared. .

The polyamic acid prepared above was bubbled through a high-speed rotation of 1,500 rpm or more. Thereafter, the defoamed polyimide precursor composition was applied to the glass substrate using a spin coater. Thereafter, the gel film was prepared by drying under a nitrogen atmosphere and at a temperature of 120 ° C. for 30 minutes, and the temperature of the gel film was raised to 450 ° C. A polyimide film was obtained by cooling at a rate of 2° C./min.

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 10 to 16 and Comparative Examples 6 to 8>

In Example 9, a polyimide film was prepared in the same manner as in Example 1, except that each of the monomers was changed as shown in Table 1 below.

dianhydride
monomer
(mole%) diamine monomer
(mole%) Polyamic acid polymerization method PMDA
(mole%) BPDA
(mole%) m-Tolidine
(mole%) PPD
(mole%) ODA
(mole%) Example 1 80 20 100 - - block polymerization Example 2 70 30 100 - - block polymerization Example 3 65 35 100 - - block polymerization Example 4 60 40 100 - - block polymerization Example 5 40 60 100 - - block polymerization Example 6 60 40 80 20 - block polymerization Example 7 60 40 80 - 20 block polymerization Example 8 65 35 90 - 10 block polymerization Example 9 80 20 100 - - random polymerization Example 10 70 30 100 - - random polymerization Example 11 65 35 100 - - random polymerization Example 12 60 40 100 - - random polymerization Example 13 40 60 100 - - random polymerization Example 14 60 40 80 20 - random polymerization Example 15 60 40 80 - 20 random polymerization Example 16 65 35 90 - 10 random polymerization Comparative Example 1 100 - 100 - - - Comparative Example 2 90 10 100 - - block polymerization Comparative Example 3 20 80 100 - - block polymerization Comparative Example 4 10 90 100 - - block polymerization Comparative Example 5 - 100 100 - - - Comparative Example 6 90 10 100 - - random polymerization Comparative Example 7 20 80 100 - - random polymerization Comparative Example 8 10 90 100 - - random polymerization

<Experimental Example 1> Physical property evaluation For the polyimide films prepared in Examples 1 to 16 and Comparative Examples 1 to 8, respectively, the glass transition temperature, the coefficient of thermal expansion, and the modulus were measured in the following manner, and the results is shown in Table 2 below. (1) 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.

(2) 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

(3) Modulus measurement

For the modulus, the polyimide film was cut to 10 mm in width and 40 mm in length, and then the modulus was measured by ASTM D-882 using Instron5564 UTM equipment from Instron. The cross head speed at this time was measured under the condition of 5 mm/min.

<Experimental Example 2> Evaluation of moisture absorption rate, dielectric constant and dielectric loss rate

For the polyimide films prepared in Examples 1 to 16 and Comparative Examples 1 to 8, respectively, moisture absorption was measured in the following manner, and the results are shown in Table 2 below.

Thereafter, for the polyimide films prepared in Examples 1 to 16 and Comparative Examples 1 to 8, respectively, copper foil was laminated on both sides in a roll-to-roll method to prepare a flexible metal clad laminate, followed by The dielectric constant and dielectric loss factor were measured in the same manner as described above, and the results are shown in Table 2 below.

(1) Measurement of moisture absorption

For moisture absorption, a specimen was prepared by cutting a polyimide film in a square with a size of 5 cm × 5 cm in accordance with the ASTMD 570 method, and the cut specimen was dried in an oven at 50° C. for at least 24 hours, then the weight was measured and the weight was measured After the measured specimen was immersed in water at 23° C. for 24 hours, the weight was measured again, and the difference in weight obtained here was measured as a percentage.

(2) Measurement of dielectric constant and dielectric loss factor

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

Dk Df moisture absorption Tg CTE Modulus (%) (℃) (ppm/℃) (GPa) Example 1 3.5 0.006 0.8 470 -4.7 15.7 Example 2 3.5 0.005 0.7 340 -4 15.2 Example 3 3.5 0.004 0.6 337 -3.2 14.2 Example 4 3.5 0.004 0.6 332 1.5 12.8 Example 5 3.4 0.004 0.6 322 -2.4 12.1 Example 6 3.5 0.005 0.7 303 -0.4 11.2 Example 7 3.5 0.004 0.6 303 7.9 8 Example 8 3.5 0.003 0.5 314 8.1 9.5 Example 9 3.6 0.005 0.7 409 -4.7 15.1 Example 10 3.5 0.004 0.6 303 7.9 8 Example 11 3.4 0.003 0.5 315 3.4 10.7 Example 12 3.4 0.003 0.5 301 7.7 9.8 Example 13 3.4 0.002 0.4 285 11.8 8 Example 14 3.5 0.002 0.5 301 13.0 7.3 Example 15 3.4 0.003 0.5 292 8.2 6.9 Example 16 3.5 0.003 0.5 303 6.5 7.6 Comparative Example 1 3.5 0.008 1.6 493 -5.5 16.7 Comparative Example 2 3.6 0.007 1.4 481 -5.1 16.2 Comparative Example 3 3.5 0.006 1.2 272 19.1 4.2 Comparative Example 4 3.5 0.005 1.1 264 21.5 3.6 Comparative Example 5 3.5 0.005 1.0 253 24.0 3.2 Comparative Example 6 3.6 0.007 1.3 478 -4.8 15.8 Comparative Example 7 3.5 0.005 1.0 266 21.1 3.5 Comparative Example 8 3.5 0.004 1.0 258 22.3 3.3

From Table 2, it can be seen that the polyimide film prepared according to the embodiment of the present invention has not only remarkably low moisture absorption, dielectric constant and dielectric loss, but also excellent glass transition temperature, coefficient of thermal expansion and modulus at desired levels. On the other hand, in the polyimide films prepared according to Comparative Examples 1 to 8, at least one of a dielectric constant, a dielectric loss factor, and a moisture absorption rate is higher than in Examples, or at least one or more of a glass transition temperature, a coefficient of thermal expansion, and a modulus. Since the physical properties are shown to be outside the range limited by the present invention, it can be seen that these are difficult to be applied to electronic components in which signal transmission is performed at a high frequency of giga units. Those of ordinary skill in the art will be able to make various applications and modifications within the scope of the present invention based on the above content.

Claims (12)

a diamine monomer including a diamine represented by the following formula (1); and
It is prepared by imidizing a polyamic acid derived from polymerization of a dianhydride monomer including pyromellitic dianhydride (PMDA) and biphenyltetracarboxylic dianhydride (BPDA), wherein the dianhydride monomer is 40 mol% to 65 mol% or less of PMDA and 35 mol% or more to 60 mol% or less of BPDA based on the total number of moles of
The polyimide polymer chain formed by imidization of the polyamic acid includes a repeating unit represented by the following Chemical Formula 2 in one polymer chain,
The modulus at 25°C is 6.5 Gpa or more, the coefficient of thermal expansion (CTE) is -5 to 13 ppm/°C, the dielectric constant (Dk) is 3.5 or less, the dielectric loss factor (Df) is 0.005 or less, and the moisture absorption is 0.7 weight % or less,
Polyimide film for use in electrical transmission circuits capable of high-frequency communication above 2 GHz:

(One)
In Formula 1, R1 and R2 are each independently a C ₁ -C ₆ alkyl group;

(2)
In Formula 2, R1 and R2 are each independently a C ₁ -C ₆ alkyl group,
n is an integer less than 10. According to claim 1,
The dianhydride monomer includes PMDA and BPDA in a molar ratio of 4: 6 to 6: 4, a polyimide film. According to claim 1,
The diamine monomer includes 80 mol% to 100 mol% of the diamine of Formula 1 based on the total number of moles thereof, the polyimide film. According to claim 1,
When the content of the diamine of Formula 1 is less than 100 mol%, the diamine monomer additionally comprises at least one selected from 1,4-phenylenediamine (PPD) and 4,4'-oxydianiline (ODA) , polyimide film. According to claim 1,
wherein R1 and R2 are each a methyl group. According to claim 1,
The glass transition temperature (Tg) is 280 ℃ or more,
The coefficient of thermal expansion (CTE) is -5 to 5 ppm/℃,
The moisture absorption is less than 1.0% by weight,
A polyimide film having a modulus of at least 12 GPa. A method for producing the polyimide film according to claim 1, comprising:
(a) polymerizing PMDA and a diamine monomer in an organic solvent to prepare a first polyamic acid;
(b) copolymerizing a second composition comprising at least one selected from the group consisting of a second polyamic acid having a composition different from that of the first polyamic acid and a monomer for preparing a polyimide and the first polyamic acid to obtain a third polyamic acid manufacturing process; and
(c) forming a film of the precursor composition containing the third polyamic acid on a support, and then imidizing;
Method of producing a polyimide film for use in an electrical transmission circuit capable of high-frequency communication of 2 GHz or higher, wherein the diamine monomer in the process (a) contains a diamine represented by the following formula (1):

(One)
In Formula 1, R1 and R2 are each independently a C ₁ -C ₆ alkyl group. 8. The method of claim 7,
The second polyamic acid is prepared by polymerizing BPDA and a diamine monomer in an organic solvent,
The diamine monomer is a method of producing a polyimide film comprising the diamine represented by the formula (1). 8. The method of claim 7,
The monomer for preparing the polyimide includes BPDA and a diamine monomer,
The diamine monomer is a method of producing a polyimide film comprising the diamine represented by the formula (1). 10. The method according to any one of claims 7 to 9,
The diamine monomer further comprises at least one selected from PPD and ODA, the method for producing a polyimide film. A flexible metal clad laminate comprising the polyimide film according to claim 1 and an electrically conductive metal foil. An electronic component comprising the flexible metal clad laminate according to claim 11 as an electrical signal transmission circuit.