Polyamic acid, polyimide film, and flexible metal foil laminate using the same

Abstract

The present invention provides a polyamic acid copolymerized with a dianhydride acid component including biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), and p-phenylenebis(trimellitate anhydride, TAHQ), and a diamine component including m-tolidine and paraphenylenediamine (PPD), a polyimide film, and a flexible metal foil laminate using the same.

Description

Technical Field

[0001] The present invention relates to a polyamic acid, a polyimide film having excellent high-temperature storage elastic modulus and low dielectric characteristics, and a flexible metal foil laminate using the same.

Background Art

[0002] Polyimide (PI) is a polymer material based on an imide ring with a very rigid aromatic main chain and having extremely excellent chemical stability, and has the highest level of heat resistance, chemical resistance, electrical insulation, chemical resistance, and weather resistance among organic materials. In particular, due to its excellent insulating properties, that is, excellent electrical properties such as a low dielectric constant, it has attracted attention as a high-functional polymer material in the fields of electricity, electronics, optics, etc.

[0003] Recently, with the weight reduction and miniaturization of electronic products, highly integrated and flexible thin circuit boards have been actively developed. Such thin circuit boards often utilize 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. As such a thin circuit board, a flexible metal foil laminate is mainly used. As an example, it includes a flexible copper foil laminate (FCCL) using a thin copper plate as the metal foil. In addition, polyimide is also used as a protective film, insulating film, etc. of the thin circuit board.

[0004] On the other hand, recently, as various functions are incorporated in electronic devices, the electronic devices are required to have high computing speed and communication speed. To meet this requirement, thin circuit boards capable of high-speed communication at high frequencies have been developed. To realize high-frequency, high-speed communication, an insulator with high impedance that can maintain electrical insulation even at high frequencies is necessary. Since impedance is inversely proportional to the frequency and dielectric constant (Dk) formed in the insulator, the dielectric constant must be as low as possible to maintain insulation even at high frequencies. However, in the case of ordinary polyimides, the dielectric properties are not currently at a level that is good enough to maintain sufficient insulation for high-frequency communication.

[0005] Furthermore, the lower the dielectric properties of the insulator, the less unwanted stray capacitance (stray capacitance) can be found in thin circuit boards. It is known that it is possible to reduce capacitance and noise generation, and to eliminate a significant portion of the causes of communication delay. Therefore, polyimide with low dielectric properties is currently recognized as the most important factor in the performance of thin circuit boards.

[0006] In particular, in the case of high-frequency communications, dielectric loss due to polyimide is inevitable. Although dissipation occurs, the dielectric dissipation factor (Df) represents the degree of electrical energy wasted by the thin circuit board and is closely related to the signal transmission delay that determines the communication speed. Therefore, maintaining the dielectric dissipation factor of polyimide as low as possible is recognized as an important factor in the performance of thin circuit boards.

[0007] Furthermore, the more moisture the polyimide film contains, the larger the dielectric constant becomes, resulting in increased dielectric loss. The loss rate increases. While polyimide films are suitable as materials for thin circuit boards due to their excellent inherent properties, they are relatively vulnerable to moisture due to the polar imide groups, which can lead to a decrease in insulation properties. Therefore, the current need is to develop polyimide films with improved dielectric properties, particularly low dielectric loss, while maintaining the unique mechanical and thermal properties of polyimide at a certain level. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Republic of Korea Patent Publication No. 10-2015-0069318 [Overview of the project] [Problems that the invention aims to solve]

[0009] Therefore, in order to solve the above problems, the objective is to provide polyamic acid, polyimide film, and flexible metal foil laminate using the same, which possess excellent high-temperature storage modulus and low dielectric properties. Therefore, the substantial objective of the present invention is to provide specific embodiments thereof. [Means for solving the problem]

[0010] To achieve the above objective, one embodiment of the present invention comprises a dianhydride acid component including biphenyltetracarboxylic dianehydride (BPDA), pyromellitic dianehydride (PMDA), and p-phenylenebis (trimellitate anhydride, TAHQ), A copolymer comprising a diamine component containing m-tolidine and paraphenylenediamine (PPD), We provide polyamic acid.

[0011] Other embodiments of the present invention include biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), and p-phenylenebis(trimellitate anhydride). Anhydride, TAHQ, and other dianhydric acid components, A polyamic acid solution containing a diamine component including m-tolidine and paraphenylenediamine (PPD) is obtained by imidizing it. We provide polyimide films.

[0012] A further embodiment of the present invention includes the polyimide film and a thermoplastic resin layer, We provide multilayer films.

[0013] A further embodiment of the present invention includes the polyimide film and an electrically conductive metal foil. We provide flexible metal foil laminates.

[0014] Yet another embodiment of the present invention includes the flexible metal foil laminate, We provide electronic components. [Effects of the Invention]

[0015] As described above, the present invention provides polyamic acid and polyimide films that possess excellent high-temperature storage modulus and low dielectric properties, comprising specific components and specific composition ratios. This makes it possible to apply these characteristics to a wide range of fields where they are required, particularly to electronic components such as flexible metal foil laminates. [Modes for carrying out the invention]

[0016] Embodiments of the present invention will be described in more detail below. Prior to this, terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention. Therefore, the configurations of the embodiments described in this specification are merely one of the most preferred embodiments of the present invention and do not represent all of the technical ideas of the present invention. It should be understood that there can be various equivalents and variations that can replace them at the time of this application.

[0017] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "including", "comprising", or "having" are intended to specify that the implemented features, numbers, steps, components, or combinations thereof exist, and it should be understood that they do not pre-exclude the possibility of the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0018] In this specification, when a quantity, concentration, or other value or parameter is given as a list of ranges, preferred ranges, or preferred upper and lower limit values, it should be understood that all ranges formed by any upper limit value or preferred value of any arbitrary upper range and any lower limit value or preferred value of any lower range are specifically disclosed, regardless of whether the range is disclosed separately. When a numerical range is mentioned in this specification, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within the range. It is intended that the scope of the present invention is not limited to the specific values mentioned when defining the range.

[0019] In this specification, "dianhydride acid" is intended to include its precursors or derivatives, which may not technically be dianhydride acids, but nevertheless should react with diamine to form polyamic acid, and this polyamic acid is converted back to polyimide.

[0020] In this specification, “diamine” is intended to include its precursors or derivatives, which may not be technically diamines, but nevertheless should react with dianehydrides to form polyamic acids, which are then converted back to polyimides.

[0021] The polyamic acid according to the present invention is copolymerized with a dianhydride acid component containing biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), and p-phenylenebis (trimellitate anhydride, TAHQ), and a diamine component containing m-tolidine and paraphenylenediamine (PPD).

[0022] In one embodiment, the polyamic acid has a content of 15 mol% or more and 70 mol% or less of the biphenyltetracarboxylic dianehydride, based on a total content of 100 mol% of the dianhydride components, and a content of 10 mol% or more and 50 mol% or less of the pyromeretic dianehydride, and the p-phenylenebis(trimelite) The content of anhydrous phosphate may be 5 mol% or more and 75 mol% or less.

[0023] Furthermore, based on a total content of 100 mol% of the diamine components, the content of m-tolidine may be 20 mol% or more and 45 mol% or less, and the content of paraphenylenediamine may be 55 mol% or more and 80 mol% or less.

[0024] In one embodiment, the polyamic acid may be a block copolymer containing two or more blocks.

[0025] The polyimide film according to the present invention is obtained by imidizing a polyamic acid solution containing a dianhydride acid component comprising biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), and p-phenylenebis (trimellitate anhydride, TAHQ), and a diamine component comprising m-tolidine and paraphenylenediamine (PPD).

[0026] In one embodiment, the polyimide film may have a biphenyltetracarboxylic dianehydride content of 15 mol% or more and 70 mol% or less, a pyromellitic dianehydride content of 10 mol% or more and 50 mol% or less, and a p-phenylenebis(trimellitate anhydride) content of 5 mol% or more and 75 mol% or less, based on a total dianhydride acid component content of 100 mol%.

[0027] As the content of p-phenylenebis(trimellitate anhydride) increases, the measured dielectric loss rate of the polyimide film decreases, and at the same time, the storage modulus at high temperatures (300°C) decreases.

[0028] Furthermore, based on a total content of 100 mol% of the diamine components, the content of m-tolidine may be 20 mol% or more and 45 mol% or less, and the content of paraphenylenediamine may be 55 mol% or more and 80 mol% or less.

[0029] In one embodiment, the polyamic acid solution undergoing the imidation reaction for the production of the polyimide film may be a block copolymer containing two or more blocks.

[0030] In one embodiment, the first block of the block copolymer may have a biphenyltetracarboxylic dianehydride content of 50 mol% or more and 60 mol% or less, based on the total content of dianhydride acid components of the polyimide film (100 mol%), and the m-tolidine content of the second block may be 30 mol% or more and 40 mol% or less, based on the total content of diamine components of the polyimide film (100 mol%). For example, the first block is obtained by imidizing biphenyltetracarboxylic dianehydride with paraphenylenediamine, and the second block is obtained by imidizing m-tolidine with pyromellitic dianehydride.

[0031] Furthermore, the entire biphenyltetracarboxylic dianehydride in the first block is imidized with paraphenylenediamine, and the entire m-tolidine in the second block is imidized with pyromeretic dianehydride.

[0032] The aforementioned m-tolidine has a hydrophobic methyl group, which contributes to the low moisture absorption properties of the polyimide film and the resulting low dielectric properties of the polyimide film.

[0033] The polyimide chain derived from the biphenyltetracarboxylic dianehydride has a structure called a charge transfer complex (CTC), which is a regular linear structure in which electron donors and electron acceptors are located in close proximity to each other, thereby enhancing intermolecular interactions. This structure has the effect of preventing hydrogen bonding with moisture, thus influencing the reduction of the moisture absorption rate and maximizing the effect of reducing the hygroscopicity of the polyimide film.

[0034] In one specific example, the dianhydride component may additionally include pyromeretic dianehydride. Pyromeretic dianehydride is a dianhydride component having a relatively rigid structure and is preferred in that it can impart appropriate elasticity to the polyimide film.

[0035] For a polyimide film to simultaneously satisfy appropriate elasticity and moisture absorption, the content ratio of dianhydride acids is particularly important. For example, the lower the content ratio of biphenyltetracarboxylic dianehydride, the less likely it is to achieve the low moisture absorption rate due to the CTC structure.

[0036] Furthermore, biphenyltetracarboxylic dianehydrides contain two benzene rings corresponding to the aromatic moiety, while pyromeretic dianehydrides contain one benzene ring corresponding to the aromatic moiety.

[0037] An increase in the pyromeretic dianehydride content in the dianhydride acid component can be understood as an increase in the number of imide groups within the molecule, relative to the same molecular weight. This can be understood as an increase in the ratio of imide groups derived from the pyromeretic dianehydride to imide groups derived from biphenyltetracarboxylic dianehydride in the polyimide polymer chain. In other words, an increase in the pyromeretic dianehydride content is seen as a relative increase in imide groups in the polyimide film as a whole, making it difficult to expect a low moisture absorption rate. Conversely, if the pyromeretic dianehydride content decreases, the relatively rigid structural components decrease, which may cause the elasticity of the polyimide film to fall below the desired level. For these reasons, if the content of biphenyltetracarboxylic dianehydride exceeds the range or the content of pyromeretic dianehydride falls below the range, the mechanical properties of the polyimide film deteriorate, making it impossible to ensure a level of heat resistance suitable for manufacturing flexible metal foil laminates. Conversely, if the content of biphenyltetracarboxylic dianehydride falls below the range, or if the content of pyromeretic dianehydride exceeds the range, it is undesirable because it is difficult to achieve appropriate levels of dielectric constant and dielectric loss rate.

[0038] In one embodiment, the polyimide film may have a dielectric loss rate (Df) of 0.003 or less and a storage modulus of 100 MPa or more as measured at 300°C. For example, the dielectric loss rate of the polyimide film may be 0.0028 or less, 0.0027 or less, 0.0026 or less, or 0.0025 or less.

[0039] Furthermore, the storage modulus of the polyimide film measured at 300°C may be 2,000 MPa or less, or 1,900 MPa or less. In connection with this, the dielectric loss rate (Df) and the storage modulus measured at 300°C all meet the requirements. In the case of the added polyimide film, it can be used as an insulating film for flexible metal foil laminates, and even when the manufactured flexible metal foil laminate is used as an electrical signal transmission circuit that transmits signals at high frequencies of 10 GHz or higher, its insulating stability is ensured and signal transmission delay is minimized.

[0040] A polyimide film that meets all of the above conditions is a novel polyimide film that has not been previously known, and the dielectric loss rate (Df) will be explained in detail below.

[0041] <Dielectric Loss Ratio> "Dielectric loss" refers to the force that is abolished by a dielectric (or insulator) when molecular friction opposes molecular motion caused by an alternating electric field. The dielectric loss rate is commonly used as an index to indicate the ease with which electric charge is lost (dielectric loss). A higher dielectric loss rate means that charge is lost more easily, while a lower dielectric loss rate means that charge is lost less easily. In other words, the dielectric loss rate is a measure of power loss, and the lower the dielectric loss rate, the more the signal transmission delay due to power loss is mitigated while maintaining a faster communication speed. This is a requirement strongly desired for polyimide films, which are insulating films, and the polyimide film according to the present invention has a dielectric loss of 0.003 or less at a very high frequency of 10 GHz.

[0042] In the present invention, the production of polyamic acid is, for example, (1) A method of polymerization by placing the entire amount of the diamine component into a solvent, and then adding the dianhydride acid component in a substantially equimolar amount to the diamine component; (2) A method of polymerization by placing the entire amount of the dianhydride acid component into a solvent, and then adding the diamine component in a substantially equimolar amount to the dianhydride acid component; (3) A method of polymerization in which, after adding some of the components of the diamine component to the solvent, some of the components of the dianhydride component are mixed with the reactant in a ratio of approximately 95 to 105 mol%, the remaining diamine component is added, followed by the remaining dianhydride component, until the diamine component and the dianhydride component are substantially equimolar; (4) A method of polymerization in which, after adding the dianhydride acid component to the solvent, a portion of the diamine compound is mixed with the reaction components in a ratio of 95 to 105 mol%, then other dianhydride acid components are added, followed by the addition of the remaining diamine components, so that the diamine components and dianhydride acid components are substantially equimolar; (5) A method of polymerization in which a portion of the diamine component and a portion of the dianhydride acid component are reacted in a solvent such that one of them is in excess to form a first composition, a portion of the diamine component and a portion of the dianhydride acid component are reacted in another solvent such that one of them is in excess to form a second composition, and then the first and second compositions are mixed to complete polymerization, wherein when forming the first composition, if the diamine component is in excess, the dianhydride acid component is in excess in the second composition, and when forming the first composition, if the dianhydride acid component is in excess, the diamine component is in excess in the second composition, and the first and second compositions are mixed so that the total amount of diamine component and dianhydride acid component used in these reactions is substantially equimolar.

[0043] However, the polymerization method is not limited to the examples above, and of course, any known method can be used to produce the first to third polyamic acids.

[0044] In one specific example, the method for producing a polyimide film according to the present invention is: Polyamic acids are produced by polymerizing a dianhydride acid component containing biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), and p-phenylenebis (trimellitate anhydride, TAHQ), with a diamine component containing m-tolidine and paraphenylenediamine (PPD). The method may include the steps of forming a film on a support containing the polyamic acid precursor composition and then imidizing it.

[0045] In the present invention, the polymerization method of polyamic acid as described above can be defined as a random polymerization method, and the polyimide film produced from the polyamic acid of the present invention produced by the process described above is preferably applicable in terms of maximizing the effect of the present invention in reducing dielectric loss rate (Df) and moisture absorption rate. However, since the polymerization method described above produces polymers with relatively short repeating units, there may be limitations in exhibiting the excellent properties of the polyimide chains derived from the dianhydride acid component. Therefore, the polymerization method of polyamic acid that is particularly preferable and usable in the present invention is the block polymerization method.

[0046] On the other hand, the solvent used to synthesize polyamic acid is not particularly limited; any solvent that can dissolve polyamic acid can be used, but an amide-based solvent is preferred. Specifically, the solvent may be an organic polar solvent, and more specifically, it may be an aprotic polar solvent, or it may be one or more selected from the group consisting of, for example, N,N-dimethylformamide (DMF), N,N-dimethylacetamide, N-methylpyrrolidone (NMP), gamma-butyrolactone (GBL), and diglyme, but it is not limited to these, and can be used individually or in combination of two or more as needed. In one example, the solvent can be N,N-dimethylformamide or N,N-dimethylacetamide, which are particularly preferred.

[0047] Furthermore, in the manufacturing process of polyamic acid, fillers may be added to improve various properties of the film, such as sliding properties, thermal conductivity, corona resistance, and loop hardness. The added fillers are not particularly limited, but preferred examples include silica, titanium dioxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, and mica.

[0048] The particle size of the filler is not particularly limited and should be determined by the film characteristics to be modified and the type of filler added. Generally, the average particle size is 0.05 to 100 μm, preferably 0.1 to 75 μm, more preferably 0.1 to 50 μm, and most preferably 0.1 to 25 μm. If the particle size falls below this range, the modification effect becomes less pronounced, and if it exceeds this range, the surface properties may be severely damaged or the mechanical properties may be significantly reduced.

[0049] Furthermore, there are no particular limitations on the amount of filler to be added; it should be determined based on the film characteristics to be modified and the particle size of the filler. Generally, the amount of filler to be added 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, per 100 parts by weight of polyimide. If the amount of filler added falls below this range, the modification effect of the filler will be less apparent, and if it exceeds this range, the mechanical properties of the film may be severely damaged. The method of adding the filler is not particularly limited, and any known method may be used.

[0050] In the manufacturing method of the present invention, the polyimide film is produced by a thermal imidation method and a chemical imidation method.

[0051] Alternatively, it may be manufactured by a composite imidation method in which thermal imidation and chemical imidation are carried out in parallel.

[0052] The aforementioned thermal imidation method is a method that eliminates chemical catalysts and induces the imidation reaction using a heat source such as hot air or an infrared dryer. The aforementioned thermal imidization method allows for the imidization of amic acid groups present in the gel film by heat-treating the gel film at a variable temperature in the range of 100 to 600°C, and more specifically, by heat-treating it at 200 to 500°C, or even more specifically, at 300 to 500°C. However, even during the gel film formation process, a portion of the amic acid (approximately 0.1 mol% to 10 mol%) is imidized, allowing the polyamic acid composition to be dried at a variable temperature in the range of 50°C to 200°C, which also falls under the category of the thermal imidization method.

[0053] In the case of chemical imidation, polyimide films can be manufactured using a dehydrating agent and an imidizing agent by methods known in the industry.

[0054] As an example of a composite imidation method, a polyimide film can be produced by adding a dehydrating agent and an imidizing agent to a polyamic acid solution, heating it at 80 to 200°C, preferably 100 to 180°C to partially cure and dry it, and then heating it at 200 to 400°C for 5 to 400 seconds.

[0055] The present invention provides a multilayer film comprising the polyimide film described above and a thermoplastic resin layer, and a flexible metal foil laminate comprising the polyimide film described above and an electrically conductive metal foil.

[0056] For example, a thermoplastic polyimide resin layer can be used as the thermoplastic resin layer.

[0057] The metal foil used is not particularly limited, but when the flexible metal foil laminate of the present invention is used in electronic or electrical equipment applications, it may include, for example, copper or copper alloys, stainless steel or its alloys, nickel or nickel alloys (including 42 alloys), aluminum or aluminum alloys.

[0058] In general flexible metal foil laminates, rolled copper foil and electrolytic copper foil are commonly used, and these can also be preferably used in the present invention. Furthermore, the surface of these metal foils may be coated with a rust-preventive layer, a heat-resistant layer, or an adhesive layer.

[0059] In the present invention, the thickness of the metal foil is not particularly limited, and any thickness that allows it to perform its function adequately depending on the application is acceptable.

[0060] The flexible metal foil laminate according to the present invention may have a structure in which a metal foil is laminated to one surface of the polyimide film, or an adhesive layer containing thermoplastic polyimide is added to one surface of the polyimide film, and the metal foil is laminated while attached to the adhesive layer.

[0061] The present invention further provides an electronic component that includes the flexible metal foil laminate as an electrical signal transmission circuit. The electrical signal transmission circuit may be an electronic component that transmits signals at a high frequency of at least 2 GHz, more specifically at a high frequency of at least 5 GHz, and even more specifically at a high frequency of at least 10 GHz.

[0062] The aforementioned electronic component may, but is not limited to, a communication circuit for a mobile terminal, a communication circuit for a computer, or a communication circuit for aerospace applications. [Examples]

[0063] The operation and effects of the invention will be described in more detail below through specific embodiments of the invention. However, these embodiments are merely presented as examples of the invention and do not define the scope of the invention's rights.

[0064] <Manufacturing example> NMP was added to a 500 ml reactor equipped with a stirrer and nitrogen injection / discharge pipes while nitrogen was injected. After setting the reactor temperature to 30°C, paraphenylenediamine (PPD) and m-tolidine were added as diamine components, and biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), and p-phenylenebis(trimellitate anhydride) (TAHQ) were added as dianhydric acid components in the specified order. Block copolymerization was carried out by heating to 40°C under a nitrogen atmosphere and stirring for 120 minutes, producing a polyamic acid with a viscosity of 200,000 cP at 23°C.

[0065] The manufactured polyamic acid was degassed by high-speed rotation of 1,500 rpm or more to remove air bubbles. Thereafter, the degassed polyimide precursor composition was coated onto a glass substrate using a spin coater. Subsequently, a gel film was produced by drying under a nitrogen atmosphere at a temperature of 120°C for 30 minutes. The gel film was then heated to 450°C at a rate of 2°C / min, heat-treated at 450°C for 60 minutes, and cooled to 30°C at a rate of 2°C / min to obtain a polyimide film.

[0066] Subsequently, the polyimide film was peeled off the glass substrate by dipping it in distilled water. The thickness of the manufactured polyimide film was 15 μm. The thickness of the manufactured polyimide film was measured using an Anritsu Electric Film Thickness Tester.

[0067] <Examples 1-7 and Comparative Examples 1-3> Based on the manufacturing examples described above, polyimide films were produced by changing the components and their contents as shown in Table 1 below.

[0068] [Table 1]

[0069] <Experimental Example> Evaluation of Dielectric Loss and Storage Modulus The dielectric loss rate and storage modulus were measured for the polyimide films produced in Examples 1 to 7 and Comparative Examples 1 to 3, and the results are shown in Table 2 below.

[0070] (1) Measurement of dielectric loss rate (Df) The dielectric loss (Df) was measured at 10 GHz using a Keysight network analyzer and a QWED SPDR resonator after drying the sample in a 130°C oven for 30 minutes and leaving it in an environment of 23°C and 50% relative humidity for 24 hours.

[0071] (2) Measurement of the storage modulus The storage modulus was determined for each film using DMA, and the value was measured at 300°C.

[0072] [Table 2]

[0073] As shown in Table 2 above, the polyimide film produced by the embodiment of the present invention not only exhibits a very low dielectric loss rate of 0.003 or less, but it can also be confirmed that the storage modulus at high temperatures is at a desired level. These results are achieved by the components and compositional ratios specified in this application, demonstrating that the content of each component plays a decisive role.

[0074] In contrast, the polyimide films of Comparative Examples 1 to 3, which have different components from the examples, exhibit a significant decrease in storage modulus properties at high temperatures, making them unsuitable for use in electronic components where high-frequency signal transmission takes place.

[0075] As described above with reference to embodiments of the present invention, a person with ordinary skill in the art to which the present invention belongs will be able to make various applications and modifications within the scope of the present invention based on the above content. [Industrial applicability]

[0076] As described above, the present invention provides polyamic acid and polyimide films that possess excellent high-temperature storage modulus and low dielectric properties, consisting of specific components and specific composition ratios, making them usefully applicable to a variety of fields where such properties are required, particularly to electronic components such as flexible metal foil laminates.

Claims

1. A dianhydride acid component containing biphenyltetracarboxylic dianehydride (BPDA), pyromellitic dianehydride (PMDA), and p-phenylenebis (trimellitate anhydride), TAHQ, A copolymer comprising a diamine component containing m-tolidine and paraphenylenediamine (PPD), It is a polyamic acid, Here, the polyamic acid is a block copolymer containing two or more blocks, Here, with a total content of the diamine component of 100 mol%, the content of m-tolidine is 20 mol% or more and 45 mol% or less, and the content of paraphenylenediamine is 55 mol% or more and 80 mol% or less. Polyamic acid.

2. Based on a total content of 100 mol% of the aforementioned dianhydride acid components, the content of the biphenyltetracarboxylic dianehydride is 15 mol% or more and 70 mol% or less, the content of the pyromellitic dianehydride is 10 mol% or more and 50 mol% or less, and the content of the p-phenylenebis(trimellitate anhydride) is 5 mol% or more and 75 mol% or less. The polyamic acid according to claim 1.

3. A dianhydride acid component containing biphenyltetracarboxylic dianehydride (BPDA), pyromellitic dianehydride (PMDA), and p-phenylenebis (trimellitate anhydride), TAHQ, A polyamic acid solution containing a diamine component including m-tolidine and paraphenylenediamine (PPD) is obtained by imidization reaction. It is a polyimide film, Here, the polyamic acid in the polyamic acid solution is a block copolymer containing two or more blocks, Here, with a total content of the diamine component of 100 mol%, the content of m-tolidine is 20 mol% or more and 45 mol% or less, and the content of paraphenylenediamine is 55 mol% or more and 80 mol% or less. Polyimide film.

4. Based on a total content of 100 mol% of the aforementioned dianhydride acid components, the content of the biphenyltetracarboxylic dianehydride is 15 mol% or more and 70 mol% or less, the content of the pyromellitic dianehydride is 10 mol% or more and 50 mol% or less, and the content of the p-phenylenebis(trimellitate anhydride) is 5 mol% or more and 75 mol% or less. The polyimide film according to claim 3.

5. The first block of the block copolymer has a biphenyltetracarboxylic dianehydride content of 50 mol% or more and 60 mol% or less, based on the total content of the dianhydride acid component of the polyimide film, which is 100 mol%. The m-tolidine content of the second block is 30 mol% or more and 40 mol% or less, based on the total content of the diamine components of the polyimide film, which is 100 mol%. The polyimide film according to claim 4.

6. The dielectric loss ratio (Df) is 0.003 or less. The storage modulus measured at 300°C is 100 MPa or higher. The polyimide film according to claim 3.

7. A polyimide film according to any one of claims 3 to 6 and a thermoplastic resin layer are included. Multilayer film.

8. A polyimide film according to any one of claims 3 to 6, and an electrically conductive metal foil, Flexible metal foil laminate.

9. Including the flexible metal foil laminate described in claim 8, Electronic components.

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