Polyimide film having high dimensional stability and method for manufacturing the same

Abstract

The present application provides a polyimide film and a method for manufacturing the same, wherein the polyimide film satisfies the following formula (1) in a dimensional change measurement using a thermal mechanical analyzer (TMA) which undergoes a temperature rising process from 25°C to 400°C, and then undergoes a cooling process from 400°C to 25°C. Formula (1) TD direction dimensional measurement value (cooling, 50°C) - TD direction dimensional measurement value (temperature rising, 50°C) < 0 µm.

Description

TECHNICAL FIELD

[0001] The present application relates to a polyimide film which maintains flatness without generating wrinkles even after coating, sputtering or evaporation of a metal foil, and a method for manufacturing the same. BACKGROUND

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

[0003] A polyimide film is attracting attention as a material for various electronic devices requiring the above-described properties.

[0004] As an example of a microelectronic component to which a polyimide film is applied, a thin circuit board having a high circuit integration degree and flexibility in order to be able to cope with the lightweight and downsizing of electronic products can be given, and a polyimide film is particularly widely used as an insulating film for a thin circuit board.

[0005] The above-described thin circuit board is generally a structure in which a circuit including a metal foil is formed on an insulating film, and such a thin circuit board is broadly referred to as a flexible metal foil clad laminate, and when a thin copper plate is used as a metal foil, it is also referred to as a flexible copper clad laminate (FCCL) in a narrow sense.

[0006] As a method for manufacturing a flexible metal foil clad laminate, for example, (i) a casting method in which polyamide acid as a precursor of a polyimide is cast or coated on a metal foil and then imidized, (ii) a metallization method in which a metal layer is directly provided on a polyimide film using sputtering, and (iii) a lamination method in which a polyimide film is joined to a metal foil by a thermoplastic polyimide using heat and pressure can be given.

[0007] In particular, the metallization method is a method in which a metal such as copper is sputtered on a polyimide film having a thickness of 20 to 38 μm, and a tie layer and a seed layer are sequentially evaporated, thereby producing a flexible metal foil clad laminate, is advantageous in forming a super-fine circuit having a pitch of 35 μm or less of a circuit pattern, and is widely used in the manufacture of a flexible metal foil clad laminate for a chip on film (COF).

[0008] In recent years, a polyimide film used in a flexible metal foil clad laminate manufactured by the metallization method or the like has a problem in that wrinkles are generated due to a decrease in flatness after lamination of a metal foil.

[0009] Therefore, there is an urgent need for a polyimide film that maintains flatness even after a metal foil is laminated.

[0010] The matters described in the above background are for the purpose of helping the understanding of the present invention and can include matters that are not prior art known to those of ordinary skill in the art.

[0011] Prior Art Documents

[0012] Patent Documents

[0013] Patent Document 1: Korean Registered Patent No. 10-1375276

[0014] Patent Document 2: Korean Laid-Open Patent Publication No. 2016-0002402 SUMMARY

[0015] Technical Problem

[0016] To this end, the present invention aims to provide a polyimide film that maintains flatness without generating wrinkles even after a metal foil is coated, sputtered, or evaporated.

[0017] However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and those skilled in the art will be able to understand other problems not mentioned from the following description.

[0018] Method of Solving the Problem

[0019] To achieve the above-mentioned object, one aspect of the present invention provides a polyimide film that satisfies the following equation (1) in a dimensional change measurement using a thermal mechanical analyzer (TMA) that undergoes a temperature increase process from 25℃ to 400℃, and then undergoes a cooling process from 400℃ to 25℃.

[0020] Equation (1)

[0021] The TD direction dimensional measurement value (cooling, 50℃) is a TD direction dimensional measurement value measured at 50℃ during the cooling process,

[0022] The TD direction dimensional measurement value (cooling, 50℃) is a TD direction dimensional measurement value measured at 50℃ during the cooling process,

[0023] The TD direction dimensional measurement value (cooling, 50℃) is a TD direction dimensional measurement value measured at 50℃ during the cooling process,

[0024] Another aspect of the present invention provides a method for manufacturing a polyimide film, which is a method for manufacturing the aforementioned polyimide film, comprising: a step of providing a polyamic acid solution obtained from an acid dianhydride component and a diamine component; a step of casting and coating the aforementioned polyamic acid solution onto a support and heating it, thereby manufacturing a self-supporting film of the polyamic acid solution; and a step of imidizing the aforementioned self-supporting film and stretching it to manufacture a polyimide film.

[0025] Another aspect of the present invention provides a flexible metal foil laminate comprising the above-described polyimide film and a conductive metal foil.

[0026] Another aspect of the present invention provides an electronic component comprising the above-described flexible metal foil laminate.

[0027] Invention Effects

[0028] The present invention provides a polyimide film with a specific range of dimensional variations, thereby providing a polyimide film with excellent flatness even after lamination with metal foil.

[0029] Such polyimide films can be applied in a variety of fields where excellent flatness is required, such as flexible metal foil laminates manufactured by metallization or electronic components containing such flexible metal foil laminates. Attached Figure Description

[0030] Figure 1 These are graphs showing the results of dimensional changes measured by a thermomechanical analyzer (TMA) during the heating process from 25°C to 400°C and then the cooling process from 400°C to 25°C of the membranes used in Examples 1 and 2 of this application.

[0031] Figure 2 These are graphs showing the results of dimensional change measurements of the membranes used in Comparative Examples 1 to 3 of this application, which underwent a heating process from 25°C to 400°C and then a cooling process from 400°C to 25°C. Detailed Implementation

[0032] Best practice

[0033] The terms or vocabulary used in this specification and the claims should not be limited to their ordinary or dictionary meanings, but should be interpreted based on the principles that the inventors can appropriately define to best illustrate their invention, and in accordance with the meanings and concepts consistent with the technical ideas of this invention.

[0034] Therefore, the constitution of the embodiments described in the present specification is only the most preferred one of the present application, and does not represent all the technical ideas of the present application, and it should be understood that there can be a variety of equivalents and modifications that can replace these embodiments at the time of filing the present application.

[0035] In the present specification, unless otherwise clearly specified in context, the singular expression includes the plural expression. In the present specification, it should be understood that the terms "comprising", "having", or "including" or the like are intended to specify the presence of the features, numbers, steps, constituent elements, or combinations thereof described, and not to preclude the presence or additional possibility of one or more other features, numbers, steps, constituent elements, or combinations thereof.

[0036] In the present specification, "acid dianhydride" is intended to include its precursors or derivatives, although they can not be acid dianhydride in the technical sense, but still react with diamine to form polyamic acid, which can be converted to polyimide again.

[0037] In the present specification, "diamine" is intended to include its precursors or derivatives, although they can not be diamine in the technical sense, but still react with dianhydride to form polyamic acid, which can be converted to polyimide again.

[0038] In the present specification, in the case where a quantity, concentration, or other value or parameter is given as a range, a preferred range, or a range of preferred upper and lower values, it is to be understood that any and all ranges formed from any of the stated upper value limits and any of the stated lower value limits are specifically contemplated.

[0039] In the present specification, in the case where a numerical range is mentioned, unless otherwise described, the range is intended to include all integers and fractions within the range of the end points. The scope of the present application is not intended to be limited to the specific values mentioned in defining the range.

[0040] The polyimide film of one embodiment of the present application satisfies the following formula (1) in a dimensional change measurement using a thermal mechanical analyzer (TMA) that undergoes a temperature rising process from 25°C to 400°C, and then undergoes a cooling process from 400°C to 25°C.

[0041] Formula (1)

[0042] TD direction (width direction of the film, perpendicular to the MD direction) dimensional change value (cooling, 50°C) - TD direction dimensional change value (temperature rising, 50°C) < 0 μm

[0043] In the above formula 1,

[0044] TD direction dimensional measurement value (cooling, 50°C) is a TD direction dimensional measurement value at 50°C during the cooling process,

[0045] TD direction dimensional measurement value (warming, 50°C) is a TD direction dimensional measurement value at 50°C at the initial stage of the warming process.

[0046] That is, as shown in the above formula (1), the value obtained by subtracting the TD direction dimensional measurement value (warming, 50°C) from the TD direction dimensional measurement value (cooling, 50°C) of the polyimide film of the present application is negative.

[0047] Such a negative calculation value is because the polyimide film shrinks in the TD direction during the cooling process after the warming.

[0048] Preferably, the value calculated according to the above formula (1) of the polyimide film of the present application can be -5 μm or less, more preferably, the value according to the above formula (1) can be -10 μm or less, more preferably, the value according to the above formula (1) can be -20 μm or less.

[0049] The polyimide film in which the value calculated according to the above formula (1) is negative maintains the flatness of the polyimide film even after a metal foil is laminated by coating, sputtering or evaporation, and wrinkles are hardly generated.

[0050] The polyimide film in which the value calculated according to the above formula (1) is 0 or more decreases in the flatness of the polyimide film after a metal foil is laminated by coating, sputtering or evaporation, and wrinkles are mostly generated.

[0051] Such a calculation value of 0 or more is because the polyimide film expands in the TD direction during the cooling process after the warming.

[0052] Here, the dimensional change measurement by the above thermal mechanical analyzer (TMA) is performed under the following conditions.

[0053] Measurement mode: tensile mode, load 5 g,

[0054] Sample length: 15 mm,

[0055] Sample width: 4 mm,

[0056] Warming start temperature: 25°C,

[0057] Warming end temperature: 400°C (without 400°C holding time),

[0058] Cooling end temperature: 25°C,

[0059] Warming and cooling rate: 10°C / min,

[0060] Measurement atmosphere: nitrogen.

[0061] The polyimide film of the present application can have a coefficient of thermal expansion (CTE) in the MD direction (continuous film formation direction; the length direction of the film, perpendicular to the TD direction) of 2 to 6.5 ppm / °C and a coefficient of thermal expansion in the TD direction of 1 to 6 ppm / °C.

[0062] In addition, the value obtained by subtracting the coefficient of thermal expansion in the TD direction from the coefficient of thermal expansion in the MD direction can be 0 or more and 2.5 ppm / °C or less.

[0063] In addition, the polyimide film can have an elastic modulus of 5 GPa or more and 11 GPa or less and a glass transition temperature of 360°C or more and 400°C or less.

[0064] On the other hand, the polyimide film of the present application can be obtained by subjecting an acid dianhydride component and a diamine component to an imidization reaction,

[0065] The acid dianhydride component can be one or more selected from the group consisting of:

[0066] pyromellitic dianhydride (PMDA), oxydiphthalic anhydride (ODPA), 3,3',4,4'-diphenyltetracarboxylic dianhydride (s-BPDA), 2,3,3',4'-diphenyltetracarboxylic dianhydride (a-BPDA), diphenyl sulfone-3,4,3',4'-tetracarboxylic dianhydride (DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylene bis(trimellitic monoester anhydride), p-biphenylene bis(trimellitic monoester anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis〔(3,4-dicarboxyphenoxy)phenyl〕propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride,

[0067] The diamine component can be one or more selected from the group consisting of:

[0068] p-phenylenediamine (PPD), m-phenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (DABA), 4,4'-oxydianiline (ODA), 3,4'-oxydianiline, 4,4'-methylenedianiline, 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'-diaminothiophenyl ether, 3,4'-diaminothiophenyl ether, 4,4'-diaminothiophenyl ether, 3,3'-diaminodiphenyl 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'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenylsulfoxide, 3,4'-diaminodiphenylsulfoxide, 4,4'-diaminodiphenylsulfoxide, 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-phenylphenoxy)benzophenone, 3,3'-diamino-4,4'-bis(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-aminophenyl sulfone)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-(3-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-(3-aminophenoxy)phenyl]sulfide, bis[4-(4- aminophenoxy)phenyl]sulfide, bis[3-(3-aminophenoxy)phenyl]sulfone, bis[3-(4- aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(4- aminophenoxy)phenyl]sulfone, bis[3-(3-aminophenoxy)phenyl]methane, bis[3-(4- aminophenoxy)phenyl]methane, bis[4-(3-aminophenoxy)phenyl]methane, bis[4-(4- aminophenoxy)phenyl]methane, 2,2-bis[3-(3-aminophenoxy)phenyl]propane, 2,2- bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 2,2-bis[3-(3- aminophenoxy)phenyl]-l,l,l,3,3,3-hexafluoropropane, 2,2-bis[3-(4- aminophenoxy)phenyl]-l,l,l,3,3,3-hexafluoropropane, 2,2-bis[4-(3- aminophenoxy)phenyl]-l,l,l,3,3,3-hexafluoropropane, and 2,2-bis[4-(4- aminophenoxy)phenyl]-l,l,l,3,3,3-hexafluoropropane.

[0069] The above-mentioned polyimide film can preferably be obtained by subjecting a polyamic acid solution having an acid dianhydride component containing one or more of 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) and pyromellitic dianhydride (PMDA) and a diamine component containing one or more of p-phenylenediamine (PPD) and 4,4'-oxydianiline (ODA) to an imidization reaction.

[0070] In addition, the content of the above 3,3',4,4'-diphenyltetracarboxylic dianhydride can be 40 mol% or more and 60 mol% or less, and the content of the above pyromellitic dianhydride can be 40 mol% or more and 60 mol% or less, based on 100 mol% of the total content of the above acid dianhydride components.

[0071] The content of the above p-phenylenediamine can be 80 mol% or more and 90 mol% or less, and the content of the above 4,4'-oxydianiline can be 10 mol% or more and 20 mol% or less, based on 100 mol% of the total content of the above diamine components.

[0072] In the present application, the production of the polyamic acid can be exemplified by the following methods:

[0073] (1) a method in which all of the diamine components are added to a solvent, and then the acid dianhydride components are added in a substantially equimolar manner to the diamine components to perform polymerization;

[0074] (2) a method in which all of the acid dianhydride components are added to a solvent, and then the diamine components are added in a substantially equimolar manner to the acid dianhydride components to perform polymerization;

[0075] (3) a method in which a part of the diamine components is added to a solvent, and then a part of the acid dianhydride components is mixed in a ratio of about 95 to 105 mol% with respect to the reaction components, and then the remaining diamine components are added, followed by the addition of the remaining acid dianhydride components, whereby the diamine components and the acid dianhydride components are polymerized in a substantially equimolar manner;

[0076] (4) a method in which the acid dianhydride components are added to a solvent, and then a part of the diamine components is mixed in a ratio of about 95 to 105 mol% with respect to the reaction components, and then the other acid dianhydride components are added, followed by the addition of the remaining diamine components, whereby the diamine components and the acid dianhydride components are polymerized in a substantially equimolar manner;

[0077] (5) a method in which a part of the diamine components and a part of the acid dianhydride components are reacted in either one of them in excess in a solvent to form a first composition, and a part of the diamine components and a part of the acid dianhydride components are reacted in either one of them in excess in another solvent to form a second composition, and then the first and second compositions are mixed and polymerization is completed, at this time, if the diamine components are in excess in the formation of the first composition, the acid dianhydride components are in excess in the second composition, and if the acid dianhydride components are in excess in the first composition, the diamine components are in excess in the second composition, whereby the first and second compositions are mixed and the entire diamine components and the acid dianhydride components used in their reactions are polymerized in a substantially equimolar manner; and the like.

[0078] In one embodiment, the method for producing the polyimide film of the present application can include:

[0079] a process of providing a polyamic acid solution obtained from an acid dianhydride component and a diamine component;

[0080] a process of casting the above polyamic acid solution on a support and heating, thereby manufacturing a self-supporting film of the polyamic acid solution; and

[0081] a process of imidizing and stretching the above self-supporting film to manufacture a polyimide film.

[0082] The above stretching is performed by biaxial stretching and tension is applied in such a manner that the stretching ratio in the MD direction is the same as that in the TD direction.

[0083] Such a stretching ratio can be confirmed by the balance between the MD direction and the TD direction of the above polyimide film through the above TMA measurement.

[0084] That is, the balance between the MD direction and the TD direction of the above polyimide film obtained by stretching is such that the value obtained by subtracting the coefficient of thermal expansion in the TD direction from the coefficient of thermal expansion in the MD direction is 0 or more and 2.5 ppm / °C or less.

[0085] In the present application, the polymerization method of the polyamic acid as described above can be defined by a random polymerization method, and the polyimide film manufactured from the polyamic acid of the present application manufactured by the above process can be preferably used in maximizing the effect of the present application in improving flatness.

[0086] However, the above polymerization method can manufacture the length of the repeating unit within the above-described high molecular chain to be short, and thus there can be limitations in exhibiting each excellent characteristic possessed by the polyimide chain derived from the acid dianhydride component. Therefore, the polymerization method of the polyamic acid that can be particularly preferably used in the present application can be a block polymerization method.

[0087] On the other hand, the solvent used for synthesizing the polyamic acid is not particularly limited, and any solvent can be used as long as it is a solvent that dissolves the polyamic acid, and an amide-based solvent is preferred.

[0088] Specifically, the above organic solvent can be an organic polar solvent, and in detail, can be an aprotic polar solvent, for example, can be one or more selected from the group consisting of N,N-dimethylformamide (DMF), N,N-dimethylacetamide, N-methyl-pyrrolidone (NMP), γ-butyrolactone (GBL), and diglyme, but is not limited thereto, and can be used alone or in combination of two or more as needed.

[0089] In one example, the above-mentioned organic solvent can be particularly preferably N,N-dimethylformamide and N,N-dimethylacetamide.

[0090] In addition, a filler can be added in the polyamide acid production step to improve various properties of the film such as sliding properties, thermal conductivity, corona resistance, loop hardness, and the like. The filler to be added is not particularly limited, and as a preferred example, there can be mentioned silica, titanium oxide, aluminum oxide, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, and the like.

[0091] The particle diameter of the filler is not particularly limited, and can be determined depending on the film properties to be improved and the kind of the filler to be added. In general, the average particle diameter is 0.05 to 100 μm, preferably 0.1 to 75 μm, more preferably 0.1 to 50 μm, and particularly preferably 0.1 to 25 μm.

[0092] If the particle diameter is lower than the above-mentioned range, the improvement effect is not easily exhibited, and if it is higher than the above-mentioned range, the surface properties are sometimes greatly damaged or the mechanical properties are greatly decreased.

[0093] In addition, the amount of the filler to be added is not particularly limited, and can be determined depending on the film properties to be improved and the particle diameter of the filler, and the like. In general, the amount of the 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, relative to 100 parts by weight of the polyimide.

[0094] If the amount of the filler to be added is lower than the above-mentioned range, the improvement effect by the filler is not easily exhibited, and if it is higher than the above-mentioned range, the mechanical properties of the film can be greatly damaged. The method of adding the filler is not particularly limited, and any publicly known method can be used.

[0095] In the production method of the present application, the polyimide film can be produced by a thermal imidization method and a chemical imidization method.

[0096] In addition, it can also be produced by a combined imidization method in which the thermal imidization method and the chemical imidization method are combined.

[0097] The above-mentioned thermal imidization method is a method in which the imidization reaction is induced by using a heat source such as a hot air dryer or an infrared dryer, without using a chemical catalyst.

[0098] In the above-mentioned thermal imidization method, the gel film can be subjected to heat treatment at a variable temperature in the range of 100 to 600°C to imidize the amic acid group present in the gel film, and in detail, the heat treatment can be performed at 200 to 500°C, and more in detail, at 300 to 500°C to imidize the amic acid group present in the gel film.

[0099] However, a part of the amic acid (about 0.1 to 10 mol%) can also be imidized during the process of forming a gel film, and for this, the polyamic acid composition can be dried at a variable temperature in the range of 50 to 200°C, which also belongs to the category of the above-mentioned thermal imidization method.

[0100] In the case of the chemical imidization method, a polyimide film can be produced using a dehydrating agent and an imidizing agent according to a method known in the art.

[0101] As an example of the composite imidization method, a polyimide film can be produced by adding a dehydrating agent and an imidizing agent to a polyamic acid solution, followed by partial curing and drying at 80 to 200°C, preferably at 100 to 180°C, and then heating at 200 to 400°C for 5 to 400 seconds.

[0102] The present application provides a flexible metal foil laminate comprising the above-mentioned polyimide film and a metal foil having electrical conductivity.

[0103] As the metal foil used, there is no particular limitation, and in the case where the flexible metal foil laminate of the present application is used in electronic or electrical equipment applications, for example, it can be a metal foil comprising copper or a copper alloy, stainless steel or an alloy thereof, nickel or a nickel alloy (including 42 alloy), aluminum or an aluminum alloy.

[0104] In general, in flexible metal foil laminates, a copper foil such as a rolled copper foil or an electrolytic copper foil is used, and the same can be preferably used in the present application. In addition, the surface of these metal foils can be coated with a rust-proof layer, a heat-resistant layer, or an adhesive layer.

[0105] In the present application, the thickness of the above-mentioned metal foil is not particularly limited, and it is only necessary to have a thickness that can sufficiently function according to its use.

[0106] The flexible metal foil laminate of the present application can be obtained by laminating, coating, sputtering, or vapor depositing a metal foil on at least one side of the above-mentioned polyimide film.

[0107] In addition, the above-mentioned flexible metal foil laminate can be used as a 2 layer (2 layer) FCCL, and in particular, it can be used in portable telephones, displays (LCD, PDP, OLED, etc.), and the like, and can be used as an FPCB, COF.

[0108] An electronic component comprising the above-mentioned flexible metal foil laminate can be, for example, a communication circuit for a portable terminal, a communication circuit for a computer, or a communication circuit for a space vehicle, but is not limited thereto.

[0109] Embodiment

[0110] Hereinafter, the effects and advantages of the present application will be described in more detail through specific production examples and examples of the present application. However, these production examples and examples are provided only as an illustration of the present application, and the scope of the claims of the present application is not limited thereto.

[0111] Production Example: Production of Polyimide Film

[0112] The polyimide film of the present application can be produced by the following general method known in the art. First, the above acid dianhydride and diamine component are reacted in an organic solvent to obtain a polyamic acid solution.

[0113] At this time, the solvent can generally use aprotic polar solvent (Aprotic solvent) as an amide-based solvent, for example, N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methyl-pyrrolidone or a combination thereof.

[0114] As for the input form of the above acid dianhydride and diamine component, it can be inputted as a powder, a block and a solution form, and it is preferable to inputted as a powder form at the initial stage of the reaction, and then inputted as a solution form to adjust the polymerization viscosity.

[0115] The obtained polyamic acid solution can be mixed with an imidization catalyst and a dehydrating agent to be coated on a support.

[0116] As an example of the catalyst used, tertiary amine (such as isoquinoline, β-methylpyridine, pyridine, etc.), as an example of the dehydrating agent, an acid anhydride, but not limited thereto. In addition, as the above used support, a glass plate, an aluminum plate, a circulating stainless steel belt or a stainless steel drum, etc. can be cited, but not limited thereto.

[0117] The film coated on the above support is gelled on the support by drying air and heat treatment.

[0118] The above gelled film is separated from the support, and drying and imidization are completed by heat treatment.

[0119] The film on which the above heat treatment is completed is heat treated under a certain tension, whereby the residual stress in the film generated in the film production process can be removed.

[0120] Specifically, in a reactor equipped with a stirrer and a nitrogen gas injection / evacuation tube, 500 ml of DMF was injected while injecting nitrogen gas, and after the temperature of the reactor was set to 30°C, diphenyltetracarboxylic acid dianhydride (50 mol%), pyromellitic acid dianhydride (50 mol%), p-phenylenediamine (13 mol%), and 4,4'-oxydianiline (87 mol%) were injected in the adjusted composition ratio and predetermined order, and allowed to completely dissolve. Thereafter, under a nitrogen atmosphere, the temperature of the reactor was increased to 40°C by heating, and stirring was continued for 120 minutes, whereby a polyamic acid having a primary reaction viscosity of 1,500 cP was produced.

[0121] The polyamic acid thus produced was stirred to a final viscosity of 100,000 to 120,000 cP.

[0122] The contents of the catalyst and the dehydrating agent were adjusted and added to the prepared final polyamic acid, and then a polyimide film was produced using an applicator.

[0123] Examples and Comparative Examples

[0124] A polyimide film was produced according to the above production example, except that the stretching degree of the examples and the comparative examples was adjusted as shown in Table 1 below.

[0125] That is, when the stretching degree of Example 1 is taken as 100%, the stretching degree of Example 2 is 120%, and the stretching degrees of Comparative Examples 1 to 3 are 150%, 140%, and 70%, respectively.

[0126] [Table 1]

[0127]

[0128] The coefficient of thermal expansion (CTE), the glass transition temperature, the elastic modulus, and the flatness after lamination with a metal foil of the produced polyimide film were measured.

[0129] In addition, after a metal layer was formed on the produced polyimide film by sputtering, the flatness of the film after coating (amount of wrinkle generation) was confirmed.

[0130] (1) Measurement of Dimensional Change

[0131] The dimensional change by a thermal mechanical analyzer (TMA) that underwent a temperature increase process from 25°C to 400°C, followed by a cooling process from 400°C to 25°C was measured.

[0132] (2) Measurement of Coefficient of Thermal Expansion

[0133] The coefficient of thermal expansion (CTE) was measured as follows: using a TA Instruments thermomechanical analyzer Model Q400, and after cutting the polyimide film to a width of 4 mm and a length of 20 mm, a tension of 0.05 N was applied under a nitrogen atmosphere while raising the temperature from room temperature to 300°C at a rate of 10°C / min, and then cooling again at a rate of 10°C / min, while measuring the slope in the range of 100°C to 200°C.

[0134] (3) Measurement of Flatness of Film

[0135] The polyimide films produced were confirmed to have no wrinkles in the MD direction by visual inspection.

[0136] (4) Measurement of Glass Transition Temperature

[0137] The glass transition temperature (Tg) was measured by determining the loss modulus and the storage modulus of each film using a DMA, and taking the inflection point in the tangent plot as the glass transition temperature. g

[0138] (5) Measurement of Elastic Modulus

[0139] The modulus of elasticity of the polyimide films was measured in accordance with the ASTM D882 standard.

[0140] The dimensional change measurement results for Examples 1 and 2 are shown in graphs in Figure 1 a, Figure 1 b, respectively. In addition, the dimensional change measurement results for Comparative Examples 1 to 3 are shown in graphs in Figure 2 a, Figure 2 b, and Figure 2 c, respectively.

[0141] As shown in Figure 1 , the calculated values according to Equation (1) for Examples 1 and 2 were negative. In addition, as shown in Figure 2 , the calculated values according to Equation (1) for Comparative Examples 1 to 3 were positive.

[0142] The post-coating film flatness measurement results were that the polyimide films of Examples 1 and 2, for which the calculated values according to Equation (1) were negative, were very excellent in film flatness (completely no or almost no wrinkles were generated) compared to the polyimide films of Comparative Examples 1 to 3, for which the calculated values according to Equation (1) were positive.

[0143] ​The embodiments of the polyimide film and the method for manufacturing a polyimide film of the present application are only preferred embodiments that enable those skilled in the art to easily practice the present application, and are not intended to limit the scope of the claims of the present application. Therefore, the true technical protection scope of the present application will be defined by the scope of the claims appended hereto. In addition, it is obvious to those skilled in the art that various substitutions, modifications and changes can be made within the scope of the technical idea of the present application, and of course, the parts that can be easily changed by those skilled in the art also belong to the scope of the claims of the present application.

[0144] Industrial applicability

[0145] The present application provides a polyimide film having a specific dimensional change range, thereby providing a polyimide film excellent in flatness even after a metal foil is laminated.

[0146] Such a polyimide film can be applied to various fields requiring a polyimide film excellent in flatness, for example, a flexible metal foil laminate manufactured by a metallization method or an electronic component containing such a flexible metal foil laminate.

Claims

1. A polyimide film satisfying the following formula (1) in a dimensional change measurement using a thermal mechanical analyzer (TMA) which undergoes a temperature rising process from 25°C to 400°C, and then undergoes a temperature cooling process from 400°C to 25°C, -32 μm ≤ the TD direction dimensional measurement value at 50°C in the cooling process - the TD direction dimensional measurement value at 50°C in the temperature rising process ≤ -20 μm Formula (1) -32 μm ≤ the TD direction dimensional measurement value at 50°C in the cooling process - the TD direction dimensional measurement value at 50°C in the temperature rising process ≤ -20 μm Formula (1) wherein, the TD direction dimensional measurement value at 50°C in the cooling process is a dimensional measurement value in the TD direction measured at 50°C in the temperature cooling process, the TD direction dimensional measurement value at 50°C in the temperature rising process is a dimensional measurement value in the TD direction measured at 50°C in the temperature rising process, the dimensional change measurement using the thermal mechanical analyzer (TMA) is performed under the following conditions: a tensile mode under a load of 5 g; a sample length of 15 mm; a sample width of 4 mm; a temperature rising and cooling rate of 10°C / min; and under a nitrogen atmosphere, wherein, when a stretching ratio in a machine direction (MD) and a transverse direction (TD) is the same and the stretching ratio is 100%, the value of formula (1) is -32 μm; when the stretching ratio is 120%, the value of formula (1) is -20 μm, and wherein, the polyimide film is obtained by subjecting a polyamic acid solution having an acid dianhydride component comprising 3,3',4,4'-diphenyltetracarboxylic dianhydride (s-BPDA) and pyromellitic dianhydride (PMDA), and a diamine component comprising p-phenylenediamine (PPD) and 4,4'-oxydianiline (ODA) to an imidization reaction, wherein, based on the total content of the acid dianhydride component being 100 mol%, the content of the 3,3',4,4'-diphenyltetracarboxylic dianhydride is 40 mol% or more and 60 mol% or less, and the content of the pyromellitic dianhydride is 40 mol% or more and 60 mol% or less, wherein, based on the total content of the diamine component being 100 mol%, the content of the p-phenylenediamine is 80 mol% or more and 90 mol% or less, and the content of the 4,4'-oxydianiline is 10 mol% or more and 20 mol% or less.

2. The polyimide film according to claim 1, wherein a thermal expansion coefficient in an MD direction is 2 to 6.5 ppm / °C, and a thermal expansion coefficient in a TD direction is 1 to 6 ppm / °C.

3. The polyimide film according to claim 2, wherein a value obtained by subtracting the thermal expansion coefficient in the TD direction from the thermal expansion coefficient in the MD direction is 0 or more and 2.5 ppm / °C or less.

4. The polyimide film according to claim 1, wherein an elastic modulus is 5 GPa or more and 11 GPa or less, and a glass transition temperature is 360°C or more and 400°C or less.

5. The polyimide film according to claim 1, wherein the polyimide film is obtained by subjecting a polyamic acid solution to an imidization reaction, the polyamic acid solution further comprising one or more acid dianhydride components and one or more diamine components, wherein the one or more acid dianhydride components are selected from the group consisting of the following compounds: ​ wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ oxydiphthalic anhydride (ODPA), 2,3,3',4'-biphenyltetracarboxylic dianhydride (a-BPDA), diphenyl sulfone-3,4,3',4'-tetracarboxylic dianhydride (DSDA), bis(3,4-dicarboxyphenyl)sulfide dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,3,3',4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), bis(3,4-dicarboxyphenyl)methane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, p-phenylenebis(trimellitic monoester anhydride), p-biphenylenebis(trimellitic monoester anhydride), m-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, p-terphenyl-3,4,3',4'-tetracarboxylic dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)biphenyl dianhydride, 2,2-bis〔(3,4-dicarboxyphenoxy)phenyl〕propane dianhydride (BPADA), 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, and 4,4'-(2,2-hexafluoroisopropylidene)diphthalic dianhydride, the one or more diamine components are selected from the group consisting of: m-phenylenediamine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,5-diaminobenzoic acid (DABA), 3,4'-diaminodiphenyl ether, 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, 3,3'-diaminodiphenyl 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'-diaminodiphenylmethane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 2,2-bis(4-aminophenyl)-1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenylsulfoxide, 3,4'-diaminodiphenylsulfoxide, 4,4'-diaminodiphenylsulfoxide, 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-phenylphenoxy)benzophenone, 3,3'-diamino-4,4'-bis(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-aminophenyl sulfone)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-(3- 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-(3- aminophenoxy)phenyl] sulfide, bis[4-(4-aminophenoxy)phenyl] sulfide, bis[3-(3- aminophenoxy)phenyl] sulfone, bis[3-(4-aminophenoxy)phenyl] sulfone, bis[4-(3- aminophenoxy)phenyl] sulfone, bis[4-(4-aminophenoxy)phenyl] sulfone, bis[3-(3- aminophenoxy)phenyl] methane, bis[3-(4-aminophenoxy)phenyl] methane, bis[4-(3- aminophenoxy)phenyl] methane, bis[4-(4-aminophenoxy)phenyl] methane, 2,2- bis[3-(3-aminophenoxy)phenyl]propane, 2,2-bis[3-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 2,2-bis[3-(3-aminophenoxy)phenyl]-l,l,l,3,3,3-hexafluoropropane, 2,2-bis[3-(4-aminophenoxy)phenyl]-l,l,l,3,3,3-hexafluoropropane, 2,2-bis[4-(3-aminophenoxy)phenyl]-l,l,l,3,3,3-hexafluoropropane, and 2,2-bis[4-(4-aminophenoxy)phenyl]-l,l,l,3,3,3-hexafluoropropane.

6. A method for producing a polyimide film according to any one of claims 1 to 5, comprising: a step of providing a polyamic acid solution obtained from an acid dianhydride component and a diamine component; a step of casting the polyamic acid solution on a support and heating, thereby producing a self-supporting film of the polyamic acid solution; and a step of imidizing and stretching the self-supporting film to produce a polyimide film.

7. A flexible metal foil laminate comprising the polyimide film according to any one of claims 1 to 5 and a metal foil having electrical conductivity.

8. The flexible metal foil laminate according to claim 7, which is formed by coating, sputtering, or vapor deposition of the metal foil.

9. An electronic component comprising the flexible metal foil laminate according to claim 8.

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