Low-dielectric polyamic acid and polyimide films

Abstract

The present invention provides a low dielectric polyamic acid and a polyimide film obtained by copolymerizing a dianhydride acid component including two or more selected from the group consisting of biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), and p-phenylenebis(trimellitate anhydride) (TAHQ), and a diamine component including one or more selected from the group consisting of diamines including one or more selected from the group consisting of oxydianiline (ODA), m-tolidine, and paraphenylenediamine (PPD).

Description

Technical Field

[0001] The present invention relates to polyamic acid and polyimide films having excellent low dielectric, adhesiveness, and heat resistance.

Background Art

[0002] Polyimide (PI) is a polymer material with an imide ring having extremely excellent chemical stability together with a rigid aromatic main chain, 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 containing 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, a flexible copper clad laminate (FCCL) using a thin copper plate for the metal foil is included. 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 inherent in electronic devices, fast computing speeds and communication speeds are required for the electronic devices. In order 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.

[0006] Therefore, polyimide with low dielectric properties is currently recognized as the most important factor in the performance of thin circuit boards. 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 a polyimide film contains, the larger its dielectric constant becomes, and the higher its dielectric loss rate. In the case of polyimide film, its excellent inherent properties make it suitable for thin circuit boards. While suitable as a material for [specific purpose], it is relatively vulnerable to moisture due to the polar imide groups, which can lead to a decrease in its insulating properties. Therefore, the current need is to develop polyimide films with improved dielectric properties, particularly low dielectric loss, while maintaining the unique mechanical, thermal, and high-adhesion surface properties of polyimide at a certain level. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Republic of Korea Patent Publication No. 10-2021-0055230 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] Therefore, in order to solve the above problems, the objective is to provide polyamic acid and polyimide films that possess excellent low dielectric properties, high adhesion, and heat resistance. 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 comprising two or more selected from the group consisting of biphenyltetracarboxylic dianehydride (BPDA), pyromellitic dianehydride (PMDA), and p-phenylenebis (trimellitate anhydride) (TAHQ), Copolymerized with a diamine component containing one or more selected from the group consisting of oxydianiline (ODA), m-tolidine, and paraphenylenediamine (PPD), We provide polyamic acid. (However, the polyamic acid must contain m-tolidine as the diamine component.)

[0011] Other embodiments of the present invention include biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), and p-phenylenebis(trimellitate anhydride). A dianhydride acid component comprising two or more types selected from the group consisting of anhydride, TAHQ, A polyamic acid solution containing a diamine component selected from the group consisting of oxydianiline (ODA), m-tolidine, and paraphenylenediamine (PPD) is obtained by imidization reaction. We provide polyimide films. (However, the polyimide film must contain m-tolidine as the diamine component.) A further embodiment of the present invention includes the polyimide film and a thermoplastic resin layer, We provide multilayer films.

[0012] A further embodiment of the present invention includes the polyimide film and an electrically conductive metal foil. We provide flexible metal foil laminates. Yet another embodiment of the present invention includes the flexible metal foil laminate, We provide electronic components. [Effects of the Invention]

[0013] As described above, the present invention provides polyamic acid and polyimide films consisting of specific components and specific composition ratios that offer low dielectric properties, high adhesion properties, and high heat resistance properties, making them usefully applicable to a variety of fields where such properties are required, particularly electronic components such as flexible metal foil laminates. [Modes for carrying out the invention]

[0014] Embodiments of the present invention will be described in more detail below. Prior to this, the terms and words used in this specification and the claims should not be construed in a limited sense according to their ordinary or dictionary meanings. Instead, in accordance with the principle that the inventor can appropriately define the concept of the terms in order to explain his invention in the best way, they should be construed in a meaning and concept that conforms to the technical idea of the present invention. Therefore, it should be understood that 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. At the time of this application, there can be various equivalents and variations that can replace these.

[0015] 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 the existence of implemented features, numbers, steps, components, or combinations thereof, and it should be understood that they do not preclude in advance the possibility of the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0016] 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 pair of any upper limit values or preferred values of any upper range, and any lower limit values or preferred values of any lower range are specifically disclosed, regardless of whether the range is disclosed separately. When a numerical range is referred to in this specification, unless otherwise stated, that range is intended to include its endpoints and all integers and fractions within that range. It is intended that the scope of the present invention is not limited to the specific values mentioned when defining the range.

[0017] As used herein, the term "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 a polyamic acid, which is then converted back to a polyimide.

[0018] As used herein, the term "diamine" is intended to include its precursors or derivatives, which may not technically be diamines, but nevertheless should react with dianhydride to form a polyamic acid, which is then converted back to a polyimide.

[0019] The polyamic acid according to the present invention is copolymerized with a dianhydride acid component containing two or more selected from the group consisting of biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), and p-phenylenebis(trimellitate anhydride) (TAHQ), and a diamine component containing one or more selected from the group consisting of oxydianiline (ODA), m-tolidine, and paraphenylenediamine (PPD). However, the polyamic acid must contain m-tolidine as the diamine component. It is possible.

[0020] Preferably, the dianhydride acid component can contain p-phenylenebis(trimellitate anhydride). For example, the dianhydride acid component may be p-phenylenebis(trimellitate anhydride) alone, a combination of p-phenylenebis(trimellitate anhydride) and biphenyltetracarboxylic dianhydride, or a combination of p-phenylenebis(trimellitate anhydride) and pyromellitic dianhydride.

[0021] Furthermore, the diamine component may be m-tolidine alone, a combination of m-tolidine and paraphenylenediamine, or a combination of m-tolidine and oxydianiline.

[0022] In one embodiment, based on a total content of 100 mol% of the dianhydride acid components, the content of the biphenyltetracarboxylic dianehydride may be 30 mol% or more and 75 mol% or less, the content of the pyromellitic dianehydride may be 60 mol% or less, and the content of the p-phenylenebis(trimellitate anhydride) may be 30 mol% or more and 70 mol% or less.

[0023] In one embodiment, based on a total content of 100 mol% of the diamine components, the content of m-tolidine may be 40 mol% or more and 100 mol% or less, the content of paraphenylenediamine may be 60 mol% or less, and the content of oxydianiline may be 60 mol% or less.

[0024] In one embodiment, the ratio of the molar percentage of m-tolidine to the molar percentage of p-phenylenebis(trimellitate anhydride) (molar percentage of m-tolidine / p-phenylenebis(trimellitate anhydride)) may be 1.1 or more and 3.5 or less. Preferably, the ratio of the molar percentage of m-tolidine to the molar percentage of p-phenylenebis(trimellitate anhydride) (molar percentage of m-tolidine / p-phenylenebis(trimellitate anhydride)) may be 1.5 or more and 2.9 or less.

[0025] The polyimide film according to the present invention is obtained by imidizing a polyamic acid solution containing two or more dianhydride acid components selected from the group consisting of biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), and p-phenylenebis (trimellitate anhydride, TAHQ), and one or more diamine components selected from the group consisting of oxydianiline (ODA), m-tolidine, and paraphenylenediamine (PPD).

[0026] The polyimide film may always contain m-tolidine as the diamine component. Preferably, the dianhydride acid component may include p-phenylenebis(trimellitate anhydride). For example, the dianhydride acid component may be p-phenylenebis(trimellitate anhydride) alone, a combination of p-phenylenebis(trimellitate anhydride) and biphenyltetracarboxylic dianehydride, or a combination of p-phenylenebis(trimellitate anhydride) and pyromeretic dianehydride.

[0027] Furthermore, the diamine component may be m-tolidine alone, a combination of m-tolidine and paraphenylenediamine, or a combination of m-tolidine and oxydianiline. stomach.

[0028] In one embodiment, based on a total content of 100 mol% of the dianhydride acid components, the content of the biphenyltetracarboxylic dianehydride may be 30 mol% or more and 75 mol% or less, the content of the pyromellitic dianehydride may be 60 mol% or less, and the content of the p-phenylenebis(trimellitate anhydride) may be 30 mol% or more and 70 mol% or less.

[0029] If the content of p-phenylenebis(trimellitate anhydrous) exceeds 70 mol%, the heat resistance of the polyimide film may decrease, making it difficult to form a film.

[0030] Furthermore, if the biphenyltetracarboxylic dianehydride content exceeds 75 mol%, the dielectric loss rate of the polyimide film may increase, leading to a decrease in its low dielectric properties.

[0031] In one embodiment, based on a total content of 100 mol% of the diamine components, the content of m-tolidine may be 40 mol% or more and 100 mol% or less, the content of paraphenylenediamine may be 60 mol% or less, and the content of oxydianiline may be 60 mol% or less.

[0032] In one embodiment, the ratio of the molar percentage of m-tolidine to the molar percentage of p-phenylenebis(trimellitate anhydride) (molar percentage of m-tolidine / p-phenylenebis(trimellitate anhydride)) may be 1.1 or more and 3.5 or less. Preferably, the ratio of the molar percentage of m-tolidine to the molar percentage of p-phenylenebis(trimellitate anhydrous) may be 1.5 or more and 2.9 or less. If the ratio of the molar percentage of m-tolidine to the molar percentage of p-phenylenebis(trimellitate anhydride) (mol% of m-tolidine / p-phenylenebis(trimellitate anhydride)) is less than 1.1 or greater than 3.5, the dielectric loss rate of the polyimide film may increase, resulting in a decrease in its low dielectric properties.

[0033] In one embodiment, the dielectric loss rate (Df) of the polyimide film may be 0.0025 or less, and the adhesive strength may be 0.8 gf / cm or more. Preferably, the dielectric loss rate of the polyimide film may be 0.0026 or less.

[0034] Furthermore, the glass transition temperature of the polyimide film may be 270°C or lower. Preferably, the glass transition temperature of the polyimide film may be 205°C or higher.

[0035] On the other hand, the polyimide film can be manufactured even at process temperatures of 400°C or higher in the film manufacturing process.

[0036] As described above, the polyimide film according to the present invention satisfies all of the above conditions, making it usable as an insulating film for flexible metal foil laminates, while also ensuring insulating stability even at high frequencies and minimizing signal transmission delay.

[0037] 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.

[0038] For example, a thermoplastic polyimide resin layer can be used as the thermoplastic resin layer. ru.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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. However, the polymerization method is not limited to the examples above, and of course, any known method can be used to produce polyamic acid.

[0046] In one specific example, the method for producing a polyimide film according to the present invention involves polymerizing a dianhydride acid component comprising two or more selected from the group consisting of biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), and p-phenylenebis (trimellitate anhydride, TAHQ), and a diamine component comprising one or more selected from the group consisting of m-tolidine and paraphenylenediamine (PPD) to produce a polyamic acid; The method may include the step of forming a film of the precursor composition containing the polyamic acid on a support, and then imidizing it.

[0047] 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 effects of the present invention, which reduce dielectric loss rate (Df), moisture absorption rate, and air permeability. 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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. If the value exceeds this, 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.

[0052] In the manufacturing method of the present invention, the polyimide film is produced by a thermal imidation method and a chemical imidation method. Alternatively, it may be manufactured by a composite imidation method in which thermal imidation and chemical imidation are carried out in parallel.

[0053] 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.

[0054] 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. 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. [Examples]

[0055] 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.

[0056] Manufacturing example: Manufacturing of polyimide film The polyimide film of the present invention can be manufactured by the following conventional method known in the industry. First, a polyamic acid solution is obtained by reacting the aforementioned dianhydride acid and diamine component with an organic solvent. In this case, the solvent can generally be an aprotic solvent, such as an amide solvent, for example, N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methylpyrrolidone, or a combination thereof. The dianhydride acid and diamine component can be added in powder, lump, or solution form. It is preferable to add them in powder form at the beginning of the reaction to allow the reaction to proceed, and then add them in solution form thereafter to adjust the polymerization viscosity. The resulting polyamic acid solution is mixed with an imidation catalyst and a dehydrating agent and then coated onto a support. Examples of catalysts used include tertiary amines (e.g., isoquinoline, β-picoline, pyridine, etc.), and examples of dehydrating agents include, but are not limited to, acid anhydrides. Furthermore, examples of supports used include, but are not limited to, glass plates, aluminum foil, circulating stainless steel belts, or stainless steel drums.

[0057] The film applied to the support is gelled on the support by dry air and heat treatment. The gelled film is separated from the support and heat-treated to complete drying and imidization. The heat-treated film is then subjected to further heat treatment under a constant tension to remove residual stresses within the film that were generated during the film-forming process.

[0058] Specifically, 500 ml of DMF was added to a reactor equipped with a stirrer and nitrogen injection / discharge pipes while nitrogen was being injected. After setting the reactor temperature to 30°C, biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), p-phenylenebis(trimellitate anhydride) (TAHQ), m-tolidine (MTD), paraphenylenediamine (PPD), and oxydianiline (ODA) were added in the adjusted composition ratio and specified order and completely dissolved. Thereafter, the reactor temperature was raised to 40°C under a nitrogen atmosphere and stirred continuously for 120 minutes to produce a polyamic acid with a primary reaction viscosity of 1,500 cP. The polyamic acid prepared in this manner was stirred until its final viscosity reached 100,000 to 120,000 cP. After adjusting the amounts of catalyst and dehydrating agent, the final polyamic acid was prepared and added, and then a polyimide film was manufactured using an applicator.

[0059] Examples and Comparative Examples As shown in Table 1 below, polyimide films were produced according to the production examples by adjusting the content of the dianhydride acid component and the diamine component in Examples 1 to 6 and Comparative Examples 1 to 3.

[0060] The polyimide films of Examples 1 to 6 were adjusted to have a ratio of mol% of m-tolidine to mol% of p-phenylenebis(trimellitate anhydride) (mol% of m-tolidine / p-phenylenebis(trimellitate anhydride)) of 1.1 to 3.5.

[0061] [Table 1]

[0062] The dielectric loss rate (Df), adhesive strength, and glass transition temperature (Tg) of the manufactured polyimide films were measured, and the film-forming properties at a process temperature of 400°C were observed, as shown in Table 2 below.

[0063] [Table 2]

[0064] In Table 2 above, "O" indicates that the film was formed at a process temperature of 400°C, and "X" indicates that the film was not formed at a process temperature of 400°C.

[0065] The methods for measuring the dielectric loss rate (Df), adhesive strength, and glass transition temperature of the manufactured polyimide film are as follows.

[0066] (1) Measurement of dielectric loss Dielectric loss rate (Df) is calculated using Keysight's ENA (Vector Network Analysis). The film was measured using the cavity resonance method (SPDR) with an analyzer after being left in an environment of 23°C / 50%RH for 24 hours.

[0067] (2) Measurement of adhesive strength Adhesion strength was tested by placing a bonding sheet (1 mil, epoxy type) on both sides of a polyimide film, positioning 1 / 2 oz copper foil on both sides, placing protective PI on top, and then heat-pressing it at a pressure of 5 MPa for 30 minutes after heating to 160°C. After cutting the film into 10 mm wide strips, a 180° peel test was performed.

[0068] (3) Measurement of glass transition temperature The glass transition temperature (Tg) was determined by using DMA to find the loss modulus and storage modulus of each film, and the inflection point in the tangent graph of these moduli was measured as the glass transition temperature.

[0069] As shown in Table 2 above, the polyimide film produced by the embodiment of the present invention not only exhibits a low dielectric loss rate of 0.0025 or less, but it was also confirmed to have an adhesive strength of 0.8 gf / cm or more. Furthermore, the glass transition temperature was below 270°C, and no problems occurred during film formation even at a process temperature of 400°C.

[0070] In contrast, Comparative Example 1, which had the same components and composition ratio of dianhydride as Example 1 but used only oxydianiline as the diamine component, showed significantly reduced heat resistance and no film was formed. Furthermore, in Comparative Example 3, which contained more than 70 mol% of p-phenylenebis(trimellitate anhydride) compared to Examples 1-3, the heat resistance was significantly reduced and no film was formed.

[0071] On the other hand, in Comparative Example 2, which was created by adjusting the ratio of mol% of m-tolidine to mol% of p-phenylenebis(trimellitate anhydride) to a ratio (mol% of m-tolidine / p-phenylenebis(trimellitate anhydride)) exceeding 3.5 compared to Examples 1-3, there were no problems with film formation, but the dielectric loss rate exceeded 0.0025 and the glass transition temperature also exceeded 270°C. Therefore, it can be seen that the low dielectric properties and heat resistance of the polyimide film of this application are achieved by the components and composition ratios specified in this application.

[0072] In contrast, Comparative Examples 1-3, which used different components and composition ratios than the Examples, exhibited higher dielectric loss rates and lower heat resistance, resulting in problems with film formation. Therefore, it can be predicted that the Comparative Examples would be unsuitable for use in electronic components where signal transmission takes place at gigabit-high frequencies.

[0073] 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]

[0074] The present invention provides polyamic acid and polyimide films consisting of specific components and specific composition ratios that offer low dielectric properties, high adhesion properties, and high heat resistance properties, making them useful in a variety of fields where such properties are required, particularly in electronic components such as flexible metal foil laminates.

Claims

1. A dianhydride acid component consisting of two or more selected from the group consisting of biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), and p-phenylenebis (trimellitate anhydride), TAHQ, Copolymerized from a diamine component consisting of one or more selected from the group consisting of oxydianiline (ODA), m-tolidine, and paraphenylenediamine (PPD), Polyamic acid, Here, with a total content of 100 mol% of the dianhydride acid components as the standard, the content of the biphenyltetracarboxylic dianehydride is 30 mol% or more and 70 mol% or less, the content of the pyromellitic dianehydride is 40 mol% or less, the content of the p-phenylenebis(trimellitate anhydride) is 30 mol% or more and 70 mol% or less, and Here, the ratio of the molar percentage of m-tolidine to the molar percentage of p-phenylenebis(trimellitate anhydrous) (mollar percentage of m-tolidine / molar percentage of p-phenylenebis(trimellitate anhydrous)) is between 1.1 and 3.

5. Polyamic acid. (However, the polyamic acid must contain m-tolidine as the diamine component.)

2. Based on a total content of 100 mol% of the diamine components, the content of m-tolidine is 40 mol% or more and 100 mol% or less. The content of the aforementioned paraphenylenediamine is 60 mol% or less. The oxydianiline content is 60 mol% or less. The polyamic acid according to claim 1.

3. A dianhydride acid component consisting of two or more selected from the group consisting of biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), and p-phenylenebis (trimellitate anhydride), TAHQ, A polyamic acid is obtained by imidizing a polyamic acid that consists of one or more diamine components selected from the group consisting of oxydianiline (ODA), m-tolidine, and paraphenylenediamine (PPD). Polyimide film, Here, with a total content of 100 mol% of the dianhydride acid components as the standard, the content of the biphenyltetracarboxylic dianehydride is 30 mol% or more and 70 mol% or less, the content of the pyromellitic dianehydride is 40 mol% or less, the content of the p-phenylenebis(trimellitate anhydride) is 30 mol% or more and 70 mol% or less, and Here, the ratio of the molar percentage of m-tolidine to the molar percentage of p-phenylenebis(trimellitate anhydrous) (mollar percentage of m-tolidine / molar percentage of p-phenylenebis(trimellitate anhydrous)) is between 1.1 and 3.

5. Polyimide film. (However, the polyimide film must contain m-tolidine as the diamine component.)

4. Based on a total content of 100 mol% of the diamine components, the content of m-tolidine is 40 mol% or more and 100 mol% or less. The content of the aforementioned paraphenylenediamine is 60 mol% or less. The oxydianiline content is 60 mol% or less. The polyimide film according to claim 3.

5. The dielectric loss (Df) measured at 10 GHz is 0.0025 or less. The adhesive strength is 0.8 gf / cm or more. The polyimide film according to claim 3.

6. A polyimide film according to any one of claims 3 to 5 and a thermoplastic resin layer are included. Multilayer film.

7. A polyimide film according to any one of claims 3 to 5, and an electrically conductive metal foil, Flexible metal foil laminate.

8. Including the flexible metal foil laminate described in claim 7, Electronic components.

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