Polyimide film and method for producing the same

Abstract

The present invention provides a polyimide film and a method for producing the same, in which, in measurement of dimensional change using a thermomechanical analyzer (TMA) after storage for 48 hours under a humidity condition of 50% RH and then undergoing a temperature rise process from 25°C to 400°C, the temperature rise thermal expansion coefficient in the TD direction (50 to 200°C) is -1.5 ppm / °C or more and 6 ppm / °C or less, the temperature rise thermal expansion coefficient (50 to 200°C) is the slope of a line connecting a dimensional measurement value in the TD direction of the polyimide film measured at 200°C in a first run during the temperature rise process and a dimensional measurement value in the TD direction of the polyimide film measured at 50°C in a first run during the temperature rise process, and the dimensional measurement value in the TD direction corresponds to a dimensional change value calculated by converting the length of the polyimide film sample used in the measurement using the thermomechanical analyzer to 1 m.

Description

Technical Field

[0001] The present invention relates to a polyimide film having excellent dimensional stability even after being exposed to humidity for a certain period of time, and a method for producing the same.

Background Art

[0002] Polyimide (PI) is a polymer material based on an imide ring with a very rigid aromatic main chain and extremely excellent chemical stability, and has the highest level of heat resistance, chemical resistance, electrical insulation, chemical resistance, and weather resistance among organic materials.

[0003] Polyimide films have attracted attention as materials for various electronic devices that require the above-described characteristics.

[0004] Examples of microelectronic components to which polyimide films are applied include thin flexible circuit boards with high circuit integration that can accommodate the weight reduction and miniaturization of electronic products. Polyimide films are particularly widely used as insulating films for thin circuit boards.

[0005] The thin circuit board generally has a structure in which a circuit including a metal foil is formed on an insulating film. Such a thin circuit board is generally referred to as a Flexible Metal Foil Clad Laminate in a broad sense. When a thin copper plate is used as the metal foil, it is sometimes referred to as a Flexible Copper Clad Laminate (FCCL) in a narrower sense. Copper Clad Laminate; FCCL)

[0006] Examples of methods for manufacturing flexible metal foil laminates include (i) a casting method in which polyamic acid, a precursor of polyimide, is cast or coated onto a metal foil and then imidized; (ii) a metallizing method in which a metal layer is directly formed on a polyimide film by sputtering; and (iii) a lamination method in which a polyimide film and a metal foil are joined by heat and pressure via a thermoplastic polyimide. In particular, the metallizing method is a method for producing flexible metal foil laminates by sputtering a metal such as copper onto a polyimide film with a thickness of 20 to 38 μm, for example, to sequentially deposit tie layers and seed layers. It has advantages in forming ultrafine circuits with a circuit pattern pitch of 35 μm or less, and is widely used in the manufacture of flexible metal foil laminates for COF (chip on film).

[0007] In fact, the polyimide film used in the manufacture of flexible metal foil laminates goes through stages such as before manufacturing, transportation, and storage, during which it is exposed to environments where humidity, temperature, and other factors change. In particular, a problem has arisen where the dimensional stability of the polyimide film deteriorates after exposure to humidity during transportation and storage, and again during the high-temperature manufacturing process of flexible metal foil laminates. Therefore, there is a pressing need for polyimide films that maintain dimensional stability even after being exposed to certain environmental conditions (especially humidity) during transportation and storage.

[0008] The matters described above in the background art are for the purpose of understanding the background of the invention and may include matters that are not prior art and are already known to a person with ordinary skill in the art to which this art belongs. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Registered Patent No. 10-1258432 of the Republic of Korea [Overview of the project] [Problems that the invention aims to solve]

[0010] Therefore, the present invention aims to provide a polyimide film that exhibits excellent dimensional stability even after exposure to humidity for a certain period of time. However, the problems that this invention aims to solve are not limited to those mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0011] To achieve the above objective, one aspect of the present invention involves storing the items for 48 hours under conditions of 50% RH humidity, In the measurement of dimensional changes using a thermomechanical analyzer (TMA) during a heating process from 25°C to 400°C, the coefficient of thermal expansion in the traverse direction (width direction) (50~200°C) was -1.5 ppm / °C or higher and 6 ppm / °C or lower. The thermal expansion coefficient during heating (50-200°C) is the slope of the line connecting the dimensional measurement value in the TD direction of the polyimide film measured at 200°C during the first run of the heating process and the dimensional measurement value in the TD direction of the polyimide film measured at 50°C during the first run of the heating process. The dimensional measurement in the TD direction corresponds to the dimensional change value calculated by converting the length of the polyimide film sample used for measurement with the thermomechanical analyzer to 1 m. We provide polyimide films.

[0012] Another aspect of the present invention provides a method for producing the polyimide film, comprising the steps of: providing a polyamic acid solution obtained from a dianhydride acid component and a diamine component; casting the polyamic acid solution onto a support and heating it to produce a self-supporting film of the polyamic acid solution; and imidizing the self-supporting film and stretching it to produce a polyimide film.

[0013] A further aspect of the present invention provides a flexible metal foil laminate comprising the polyimide film and an electrically conductive metal foil.

[0014] Yet another aspect of the present invention provides an electronic component including the flexible metal foil laminate. [Effects of the Invention]

[0015] The present invention provides a polyimide film that exhibits excellent dimensional stability even after exposure to humidity for a certain period of time, thereby providing a polyimide film that exhibits excellent dimensional stability even during the lamination process of metal foils. Such polyimide films are applicable to a variety of fields where polyimide films with excellent dimensional stability are required, such as flexible metal foil laminates manufactured by metallizing methods or electronic components containing such flexible metal foil laminates. [Brief explanation of the drawing]

[0016] [Figure 1] This graph shows the results of dimensional change measurements performed by a thermomechanical analyzer (TMA) on polyimide films of Examples 1 and 4 of the present application, during a heating process from 25°C to 400°C. [Figure 2] This graph shows the results of dimensional change measurements performed by a thermomechanical analyzer (TMA) on the polyimide films of Comparative Examples 1 and 4 of the present application, under a heating process from 25°C to 400°C. [Modes for carrying out the invention]

[0017] 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. In accordance with the principle that the inventor can appropriately define the concept of the terms in order to best explain his invention, they must be construed in a meaning and concept consistent with the technical idea of the present invention.

[0018] Therefore, it should be understood that the configurations of the embodiments described in this specification are only 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.

[0019] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprising," "including," or "having" are intended to specify the presence of implemented features, numbers, steps, components, or combinations thereof, and it should be understood that they do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0020] 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 should be converted back to polyimide.

[0021] In this specification, "diamine" is intended to include its precursors or derivatives, which may not technically be diamines, but nevertheless should react with dianhydride to form polyamic acid, and this polyamic acid should be converted back to polyimide.

[0022] Wherever a quantity, concentration, or other value or parameter is given in this specification as an enumeration of ranges, preferred ranges, preferred upper limits, and preferred lower limits, it should be understood that all ranges formed by any pair of limits or preferred values ​​of any upper range and any limits or preferred values ​​of any lower range are specifically disclosed, regardless of whether the ranges are disclosed separately.

[0023] Where a range of numbers is referred to herein, unless otherwise specified, that range is intended to include its endpoint and all integers and fractions within that range. The scope of the present invention is not intended to be limited to the specific values ​​referred to when defining a range.

[0024] In one embodiment of the present invention, a polyimide film has a thermal expansion coefficient (50-200°C) of -1.5 ppm / °C or more and 6 ppm / °C or less when measuring dimensional changes using a thermomechanical analyzer (TMA) during a heating process from 25°C to 400°C. The thermal expansion coefficient (50-200°C) may be the slope of the line connecting the dimensional measurement value in the TD direction of the polyimide film measured at 200°C during the first run of the heating process and the dimensional measurement value in the TD direction of the polyimide film measured at 50°C during the first run of the heating process.

[0025] Furthermore, the dimensional measurement value in the TD direction can correspond to the dimensional change value calculated by converting the length of the polyimide film sample used for measurement with the thermomechanical analyzer to 1 m. In other words, the polyimide film of the present invention has a first run (Fir) during the heating process. The slope of the line connecting the dimensional measurement in the TD direction of the polyimide film measured at 200°C during the first run and the dimensional measurement in the TD direction of the polyimide film measured at 50°C during the first run is -1.5 ppm / °C or greater.

[0026] Polyimide films expand in the MD (machine direction, longitudinal direction) and TD (traverse direction, width direction) directions during the heating process. However, in actual FCCL manufacturing, the pattern progresses in the MD direction, while the PI film and Cu layer form a repeating pattern in the TD direction. Therefore, expansion and contraction, particularly in the TD direction, are important factors in determining the quality of FCCL.

[0027] The slope of the straight line in the polyimide film of the present invention may preferably be 5.5 ppm / °C or less, and more preferably 5.0 ppm / °C or less. Polyimide films with a linear slope of -1.5 ppm / °C or higher and 6 ppm / °C or lower exhibited excellent dimensional stability even after exposure to humidity for a certain period of time, and the dimensional stability of the polyimide film was maintained even after lamination of metal foil by coating, sputtering, and / or vapor deposition. Polyimide films with a linear slope of less than -1.5 ppm / °C or greater than 6 ppm / °C showed reduced dimensional stability after exposure to humidity for a certain period of time, resulting in a significant decrease in the quality of flexible metal foil laminates laminated by coating, sputtering, and / or vapor deposition.

[0028] Here, the measurement of dimensional changes using the thermomechanical analyzer (TMA) was performed under the following conditions. Measurement mode: Tensile mode, load 5g, Sample length: 16 mm (length in the width direction), Sample width: 4 mm, Temperature at which heating begins: 25℃, Heating termination temperature: 400°C (there is no maintenance time at 400°C)

[0029] The coefficient of thermal expansion (CTE) in the TD direction of the polyimide film of the present invention may be 1 ppm / °C or more and 10 ppm / °C or less.

[0030] Furthermore, the moisture absorption rate of the polyimide film may be 1.5 wt% or less.

[0031] On the other hand, the polyimide film of the present invention contains pyromeretic dianehydride (PMDA), oxydiphthalic dianehydride (ODPA), 3,3',4,4'-biphenyltetracarboxylic dianehydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianehydride (a-BPDA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianehydride (DSDA), bis(3,4-dicarboxyphenyl) sulfide dianehydride, and 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropyl Pandiane hydride, 2,3,3',4'-benzophenone tetracarboxylic dianehydride, 3,3',4,4'-benzophenone tetracarboxylic dianehydride (BTDA), bis(3,4-dicarboxyphenyl)methanedianehydride, 2,2-bis(3,4-dicarboxyphenyl)propanedianehydride, p-phenylenebis(trimeltic monoester acid anhydride), p-biphenylenebis(trimeltic monoester acid anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianehydride, p- One or more dianhydride acid components selected from the group consisting of terphenyl-3,4,3',4'-tetracarboxylic dianehydride, 1,3-bis(3,4-dicarboxyphenoxy)benzenedianehydride, 1,4-bis(3,4-dicarboxyphenoxy)benzenedianehydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyldianehydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propanedianehydride (BPADA), 2,3,6,7-naphthalenetetracarboxylate dianehydride, 1,4,5,8-naphthalenetetracarboxylic dianehydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianehydride, Paraphenylenediamine (PPD), metaphenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (DABA), 4,4'-diaminodiphenyl ether (ODA), 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane (methylenediamine), 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(trifluoro Methyl)-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'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl Minodiphenyl sulfide, 3,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 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'-diaminodi Phenylmethane, 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'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis(3-aminophenoxy)benzene (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-aminophenyl sulfide)benzene, 1,3-bis(4-aminophenyl sulfide)benzene, 1,4-bis(4-aminophenyl sulfide)benzene, 1,3-bis(3-aminophenyl sulfone)benzene, 1,3-bis(4-aminophenyl Sulfone)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-bis[2-(4-aminophenyl)isopropyl]benzene, 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-(4-aminophenoxy, )phenyl] ether, bis[3-(3-aminophenoxy)phenyl] ketone, bis[3-(4-aminophenoxy)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 -(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)phenyl]sulfone, bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4-aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl] 2,2-bis[3-(3-aminophenoxy)phenyl]methane, bis[4-(4-aminophenoxy)phenyl]methane, 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-hex It is obtained by imidizing and reacting with one or more diamine components selected from the group consisting of safluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane, and 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane.

[0032] The polyimide film is preferably obtained by imidizing a polyamic acid solution containing a dianhydride acid component comprising one or more selected from the group consisting of 3,3',4,4'-biphenyltetracarboxylic dianehydride (s-BPDA), pyromeretic dianehydride (PMDA), and 3,3',4,4'-benzophenonetetracarboxylic dianehydride (BTDA), and a diamine component comprising one or more selected from the group consisting of paraphenylenediamine (PPD), 4,4'-diaminodiphenyl ether (ODA), and 2,2'-dimethylbenzidine.

[0033] Furthermore, based on a total content of 100 mol% of the dianhydride acid components, the content of 3,3',4,4'-biphenyltetracarboxylic dianehydride may be 100 mol% or less, the content of pyromeretic dianehydride may be 55 mol% or less, and the content of 3,3',4,4'-benzophenonetetracarboxylic dianehydride may be 60 mol% or less.

[0034] On the other hand, based on a total content of 100 mol% of the diamine components, the content of paraphenylenediamine may be 50 mol% or more and 100 mol% or less, the content of 4,4'-diaminodiphenyl ether may be 20 mol% or less, and the content of 2,2'-dimethylbenzidine may be 50 mol% or less.

[0035] If the pyromeretic dianehydride content exceeds 55 mol%, the moisture absorption rate becomes very high, which can reduce the dimensional stability of the manufactured polyimide film against moisture. On the other hand, if the 3,3',4,4'-benzophenone tetracarboxylic dianehydride content exceeds 60 mol%, the modulus of the manufactured polyimide film becomes very high, and brittle properties may appear.

[0036] Furthermore, if the content of paraphenylenediamine is less than 50 mol%, or the content of 4,4'-diaminodiphenyl ether is more than 20 mol%, the thermal expansion coefficient of the manufactured polyimide film may become excessively high, leading to a decrease in thermal dimensional stability. On the other hand, if the 2,2'-dimethylbenzidine content exceeds 50 mol%, the modulus of the manufactured polyimide film becomes very high, and brittle properties may appear.

[0037] 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 the dianhydride acid component is in excess in the first composition, 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, and so on.

[0038] In one specific example, the method for producing a polyimide film according to the present invention is: A step of providing a polyamic acid solution obtained from a dianhydride acid component and a diamine component, A step of producing a self-supporting film of the polyamic acid solution by casting the polyamic acid solution onto a support and heating it, The process may include imidizing the self-supporting film and stretching it to produce a polyimide film.

[0039] 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 improving flatness.

[0040] 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 preferably usable in the present invention is block polymerization.

[0041] 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 organic solvent may be an organic polar solvent, and more specifically, an aprotic solvent. It may be an aprotic polar solvent, or one or more selected from the group consisting of, for example, N,N-dimethylformamide (DMF), N,N-dimethylacetamide, N-methylpyrrolidone (NMP), gammabutyrolactone (GBL), and diglyme, but is not limited thereto, and can be used individually or in combination of two or more as needed. In one example, the organic solvent can be N,N-dimethylformamide or N,N-dimethylacetamide, which are particularly preferred.

[0042] 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.

[0043] 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.

[0044] Furthermore, the amount of filler to be added is not particularly limited and 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.

[0045] In the manufacturing method of the present invention, polyimide film can be produced by thermal imidation and chemical imidation. Alternatively, it may be produced by a composite imidation method in which thermal imidation and chemical imidation are carried out in parallel.

[0046] 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.

[0047] The aforementioned thermal imidation method can imidize the 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, and even more specifically, at 300 to 500°C to imidize the amic acid groups present in the gel film.

[0048] However, even during the gel film formation process, a portion of the amic acid (about 0.1 mol% to 10 mol%) may be imidized, and for this reason, the polyamic acid composition can be dried at a variable temperature in the range of 50°C to 200°C, which may also be included in the scope of the thermal imidization method.

[0049] 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.

[0050] 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. The present invention provides a flexible metal foil laminate comprising the polyimide film described above and an electrically conductive metal foil.

[0051] 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. 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.

[0052] In the present invention, the thickness of the metal foil is not particularly limited, and any thickness that allows it to perform adequately according to its application is acceptable.

[0053] The flexible metal foil laminate according to the present invention is obtained by laminating, coating, sputtering, or depositing a metal foil onto at least one surface of the polyimide film. Furthermore, the flexible metal foil laminate can be used as a 2-layer FCCL, and is particularly suitable for use in mobile phones, displays (LCD, PDP, OLED, etc.), and is suitable for use in FPCBs and COFs.

[0054] The electronic component including the flexible metal foil laminate may be, for example, a communication circuit for a mobile terminal, a communication circuit for a computer, or a communication circuit for aerospace applications, but is not limited thereto. [Examples]

[0055] The operation and effects of the invention will be described in more detail below through specific manufacturing examples and embodiments. However, these manufacturing examples and embodiments are merely presented as examples of the invention and do not limit 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. 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 may be mixed with an imidation catalyst and a dehydrating agent and applied to a support.

[0057] 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.

[0058] 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.

[0059] 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, 3,3',4,4'-biphenyltetracarboxylic dianehydride (BPDA), pyromeretic dianehydride (PMDA), 3,3',4,4'-benzophenonetetracarboxylic dianehydride (BTDA), paraphenylenediamine (PPD), 4,4'-diaminodiphenyl ether (ODA), and 2,2'-dimethylbenzidine (MTD) were added in the adjusted composition ratio and specified order and completely dissolved. Thereafter, under a nitrogen atmosphere, the reactor temperature was raised to 40°C and stirring was continued for 120 minutes while heating 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.

[0060] Examples and Comparative Examples Polyimide films were produced according to the above-mentioned manufacturing example, provided that the content of dianhydride acid and diamine components in the examples and comparative examples was adjusted as shown in Table 1 below.

[0061] [Table 1]

[0062] The dimensional measurements (at 200°C), dimensional measurements (at 50°C), coefficient of thermal expansion (CTE), and moisture absorption rate of the manufactured polyimide film were measured and are shown in Table 2 below.

[0063] (1) Measurement of the coefficient of thermal expansion After storing the polyimide film at a humidity of 50% RH for 48 hours, the changes in the polyimide film's dimensions were measured using a thermomechanical analyzer (TMA) during a heating process from 25°C to 400°C at 50°C and 200°C, respectively. The measurement taken at 200°C during the first run of the heating process was then performed. The slope of the straight line connecting the dimensional measurement of the film and the dimensional measurement of the polyimide film measured at 50°C during the first run of the heating process was calculated. Typically, the coefficient of thermal expansion (CTE) is measured by the slope in ppm / °C during the cooling phase of the first run and the heating phase of the second run of a thermomechanical analyzer (TMA). However, in order to simulate the actual process and measure the dimensional changes of polyimide film affected by moisture, it is necessary to measure the slope (ppm / °C) of the heating phase of the first run of the thermomechanical analyzer (TMA), as in the present invention.

[0064] (2) Measurement of the coefficient of thermal expansion The coefficient of thermal expansion (CTE) is measured using a thermomechanical analyzer from TA Corporation. The analyzer used is a Q400 model. A polyimide film is cut to a width of 4 mm and a length of 20 mm, and the sample measurement length is 16 mm. In this case, the longitudinal direction of the sample measurement is the TD direction. Under a nitrogen atmosphere, the temperature was raised from room temperature to 400°C at a rate of 10°C / min while applying a tension of 0.05 N. Then, while cooling again at a rate of 10°C / min, the gradient in the range from 50°C to 200°C was measured. In other words, the coefficient of thermal expansion corresponds to the gradient measured during the cooling process after the heating. On the other hand, the thermal expansion coefficient corresponding to the slope measured during the cooling process of the First Run shows a value similar to the normal thermal expansion coefficient corresponding to the slope measured during the heating process of the Second Run.

[0065] (3) Measurement of moisture absorption rate The moisture absorption rate was determined according to the ASTM D570 method. Test specimens were prepared by cutting polyimide film into 5cm x 5cm squares, drying the cut specimens in a 50°C oven for more than 24 hours, measuring their weight, immersing the weighed specimens in 23°C water for 24 hours, and measuring their weight again. The difference in weight obtained was expressed as a percentage.

[0066] [Table 2]

[0067] The polyimide films of Examples 1-6 have a coefficient of thermal expansion (50-200°C) of -1.5 This corresponds to a concentration between ppm / °C and 6 ppm / °C. In other words, as shown in the graphs of the dimensional change measurement results for the polyimide films of Examples 1 and 4 in Figures 1A and 1B, respectively, it was confirmed that the range of the thermal expansion coefficient during heating, which is the slope of the straight line connecting the dimensional measurement value in the TD direction of the polyimide film measured at 200°C during the heating process and the dimensional measurement value in the TD direction of the polyimide film measured at 50°C during the heating process, is between -1.5 ppm / °C and 6 ppm / °C. On the other hand, in the dimensional change measurement result graphs in Figures 1A and 1B, the dimensional change value on the Y axis represents the dimensional change value corresponding to the length (16 mm) of the polyimide film sample used for TMA measurement. The coefficient of thermal expansion during temperature increase (50-200°C) was calculated using the slope obtained by converting the measurement results of the dimensional change measurement graph to the dimensional change value per meter of polyimide film length.

[0068] Furthermore, the polyimide films of Examples 1 to 6 had a thermal expansion coefficient in the TD direction of 1 ppm / °C or more and 10 ppm / °C or less, and a moisture absorption rate of 1.5 wt% or less. In contrast, the polyimide films of Comparative Examples 1 and 4 had a pyromeretic dianehydride content exceeding 55 mol%, while the polyimide film of Comparative Example 5 had a paraphenylenediamine content of less than 50 mol% and a 2,2'-dimethylbenzidine content exceeding 50 mol%. Therefore, the polyimide films of Comparative Examples 1, 4, and 5 exhibited high moisture absorption rates and very low coefficients of thermal expansion during cooling, resulting in shrinkage and a coefficient of thermal expansion during heating (50-200°C) of less than -1.5 ppm / °C. In other words, as shown in the graphs of the dimensional change measurement results for comparative examples 1 and 4 of the polyimide film in Figures 2A and 2B, respectively, the slope of the straight line connecting the dimensional measurement value in the TD direction of the polyimide film measured at 200°C during the heating process and the dimensional measurement value in the TD direction of the polyimide film measured at 50°C during the heating process, converted to a dimensional change value per meter of polyimide film length, corresponds to less than -1.5 ppm / °C.

[0069] On the other hand, the polyimide films of Comparative Examples 2 and 3 had a paraphenylenediamine content of less than 50 mol% and a 4,4'-diaminodiphenyl ether content of more than 20 mol%. As a result, the coefficient of thermal expansion during temperature increase (50-200°C) becomes very large, exceeding the range of the polyimide film of the present invention. This leads to a very large coefficient of thermal expansion in the TD direction, resulting in a decrease in the dimensional stability of the polyimide film.

[0070] The embodiments of the polyimide film and method for producing the polyimide film of the present invention are merely preferred embodiments that enable a person skilled in the art with ordinary skill in the art to easily implement the present invention, and are not limited to the embodiments described above; therefore, the scope of the rights of the present invention is not limited by them. Accordingly, the true scope of technical protection of the present invention must be determined by the technical idea of ​​the attached claims. Furthermore, it is obvious to a person skilled in the art that various substitutions, modifications, and alterations are possible without departing from the technical idea of ​​the present invention, and it is self-evident that parts that can be easily altered by a person skilled in the art are also included in the scope of the rights of the present invention. [Industrial applicability]

[0071] The present invention provides a polyimide film that exhibits excellent dimensional stability even after exposure to humidity for a certain period of time, thereby providing a polyimide film that exhibits excellent dimensional stability even during the lamination process of metal foils. Such polyimide films are applicable to a variety of fields where polyimide films with excellent dimensional stability are required, such as flexible metal foil laminates manufactured by metallizing methods or electronic components containing such flexible metal foil laminates.

Claims

1. After storage for 48 hours under conditions of 50% RH humidity, In the measurement of dimensional changes using a thermomechanical analyzer (TMA) during a heating process from 25°C to 400°C, the coefficient of thermal expansion in the TD direction (50-200°C) was -1.5 ppm / °C or higher and 6 ppm / °C or lower. The coefficient of thermal expansion during heating (50 to 200°C) is the slope of the line connecting the dimensional measurement of the polyimide film in the TD direction measured at 200°C during the first run of the heating process and the dimensional measurement of the polyimide film in the TD direction measured at 50°C during the first run of the heating process. The dimensional measurement in the TD direction corresponds to the dimensional change value calculated by converting the length of the polyimide film sample used for measurement with the thermomechanical analyzer to 1 m. The aforementioned polyimide film is obtained by imidizing a polymeric acid solution containing a pyromeretic dianhydride (PMDA) and a diamine component containing paraphenylenediamine (PPD). Based on a total content of 100 mol% of the aforementioned dianhydride components, the content of the pyromeretic dianehydride is 55 mol% or less, and Based on a total content of 100 mol% of the diamine components, the content of the paraphenylenediamine is 50 mol% or more and 100 mol% or less. Polyimide film.

2. The coefficient of thermal expansion in the TD direction is 1 ppm / °C or more and 10 ppm / °C or less. The polyimide film according to claim 1.

3. The moisture absorption rate is 1.5 wt% or less. The polyimide film according to claim 1.

4. The polyimide film is oxydiphthalic dianehydride (ODPA), 3 ,3',4,4'-biphenyltetracarboxylic dianehydride (s-BPDA), 2,3,3',4'-biphenyltetracarboxylic dianehydride (a-BPDA), diphenylsulfone-3,4,3',4'-tetracarboxylic dianehydride (DSDA), bis(3,4-dicarboxyphenyl) sulfide dianehydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoro Propanedian hydride, 2,3,3',4'-benzophenone tetracarboxylic dianehydride, 3,3',4,4'-benzophenone tetracarboxylic dianehydride (BTDA), bis(3,4-dicarboxyphenyl)methanedianehydride, 2,2-bis(3,4-dicarboxyphenyl)propanedianehydride, p-phenylenebis(trimeltic monoester acid anhydride), p-biphenylene Bis(trimeltic monoester acid anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianehydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianehydride, 1,3-bis(3,4-dicarboxyphenoxy)benzenedianehydride, 1,4-bis(3,4-dicarboxyphenoxy)benzenedianehydride, 1,4-bis(3,4-dicarboxyphenoxy) The dianhydride component further comprises one or more dianhydrides selected from the group consisting of phenyl dianehydride, 2,2-bis[(3,4-dicarboxyphenoxy)phenyl]propanedianehydride (BPADA), 2,3,6,7-naphthalenetetracarboxylate dianehydride, 1,4,5,8-naphthalenetetracarboxylic dianehydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic acid dianehydride, Metaphenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (DABA), 4,4'-diaminodiphenyl ether (ODA), 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'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfide, 3,4'-di Aminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 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-amino Phenyl)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'-diaminodiphenyl sulfoxide, 3,4'-diaminodiphenyl sulfoxide, 4,4'-diaminodiphenyl sulfoxide, 1,3-bis(3-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(3-aminophenyl)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenoxy)benzene (TPE-R), 1,4-bis(3-aminophenoxy)benzene (TPE-Q), 1,3-bis(3-aminophenoxy)-4-trifluoromethylbenzene, 3,3'-diamino-4-(4-phenyl)phenoxybenzophenone, 3,3'-diamino-4,4'-di(4-phenylpheno, Xy)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-(4-aminophenyl)isopropyl]benzene, 1,4-bis[2-(4-aminophenyl] [phenyl)isopropyl]benzene, 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]keto n, bis[3-(4-aminophenoxy)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[ 4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4-aminophenoxy)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,The diamine component further comprises one or more diamines selected from the group consisting of 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]-1,1,1,3,3,3-hexafluoropropane, and 2,2-bis[4-(4-aminophenoxy)phenyl]-1,1,1,3,3,3-hexafluoropropane. The reaction, which involves imidizing the two, The polyimide film according to claim 1.

5. The polyimide film further comprises the dianhydride acid component, which is selected from the group consisting of 3,3',4,4'-biphenyltetracarboxylic dianehydride (s-BPDA) and 3,3',4,4'-benzophenonetetracarboxylic dianehydride (BTDA), A polyamic acid solution containing the diamine component, further comprising one or more selected from the group consisting of 4,4'-diaminodiphenyl ether (ODA) and 2,2'-dimethylbenzidine, is obtained by imidizing it. The polyimide film according to claim 1.

6. Based on a total content of 100 mol% of the aforementioned dianhydride acid components, the content of the 3,3',4,4'-biphenyltetracarboxylic dianehydride is 100 mol% or less, and the content of the 3,3',4,4'-benzophenonetetracarboxylic dianehydride is 60 mol% or less. The polyimide film according to claim 5.

7. Based on a total content of 100 mol% of the diamine components, the content of 4,4'-diaminodiphenyl ether is 20 mol% or less, and the content of 2,2'-dimethylbenzidine is 50 mol% or less. The polyimide film according to claim 5.

8. A method for producing a polyimide film according to any one of claims 1 to 7, A step of providing a polyamic acid solution obtained from a dianhydride acid component and a diamine component, A step of producing a self-supporting film of the polyamic acid solution by casting the polyamic acid solution onto a support and heating it, The process includes imidizing the self-supporting film and stretching it to produce a polyimide film. A method for manufacturing polyimide film.

9. A polyimide film according to any one of claims 1 to 7, and an electrically conductive metal foil, Flexible metal foil laminate.

10. The metal foil is formed by coating, sputtering, or vapor deposition. The flexible metal foil laminate according to claim 9.

11. Including the flexible metal foil laminate described in claim 10, Electronic components.

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