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

Abstract

The present invention provides a polyimide film with excellent dimensional stability and a method for manufacturing the same. The polyimide film has a coefficient of thermal expansion of 1 ppm / ℃ or higher and 5 ppm / ℃ or lower, an elastic modulus of 9 GPa or higher and 11.5 GPa or lower, and a glass transition temperature of 340℃ or higher and 400℃ or lower.

Description

Technical Field

[0001] This invention relates to polyimide films with high dimensional stability, and more specifically, to polyimide films with high thermal and moisture dimensional stability, and methods for manufacturing the same. Background Technology

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

[0003] Polyimide films have attracted much attention as a material for various electronic devices that require the above-mentioned properties.

[0004] As an example of microelectronic components using polyimide films, polyimide films are particularly widely used as insulating films for thin circuit boards that are highly integrated and flexible, in order to meet the needs of lightweighting and miniaturization of electronic products.

[0005] The aforementioned thin circuit board is generally a structure in which a circuit containing a metal foil is formed on an insulating film. In a broad sense, such a thin circuit board is called a flexible metal foil laminate. When a thin copper plate is used as the metal foil, it is also called a flexible copper foil laminate (FCCL) in a narrow sense.

[0006] Methods for manufacturing flexible metal foil laminates include, for example: (i) a casting method in which polyamic acid, as a precursor of polyimide, is cast or coated onto a metal foil and then imidized; (ii) a metallization method in which a metal layer is directly deposited on a polyimide film by sputtering; and (iii) a lamination method in which a polyimide film is bonded to a metal foil by using thermoplastic polyimide and heat and pressure.

[0007] In particular, the metallization method, which involves sputtering a metal such as copper onto a polyimide film with a thickness of 20 to 38 μm and then sequentially depositing a tie layer and a seed layer to produce a flexible metal foil laminate, is advantageous for forming ultra-fine circuits with a circuit pattern pitch of less than 35 μm and is widely used in the manufacture of flexible metal foil laminates for chip-on-film (COF) applications.

[0008] The polyimide film used in flexible metal foil laminates produced by metallization needs to have high dimensional stability. Dimensional stability is typically determined by thermal dimensional stability, expressed as the coefficient of thermal expansion; however, moisture dimensional stability, expressed as the coefficient of hygroscopic expansion, is becoming increasingly important, just as much as thermal dimensional stability.

[0009] That is, the demand for polyimide films with excellent thermal dimensional stability and moisture dimensional stability is constantly increasing. In the case of polyimide films with low thermal expansion coefficient and high thermal dimensional stability in actual design, there is a problem of reduced moisture dimensional stability.

[0010] Therefore, there is an urgent need for polyimide films that can balance high thermal dimensional stability and high dimensional stability against moisture.

[0011] The matters described in the background section above are intended to aid in understanding the background of the invention and may include matters that are not known to those skilled in the art.

[0012] Existing technical documents

[0013] Patent documents

[0014] Patent Document 1: Korean Patent Registration No. 10-1375276

[0015] Patent Document 2: Korean Patent Publication No. 2016-0002402 Summary of the Invention

[0016] Technical issues

[0017] Therefore, the object of the present invention is to provide a polyimide film that simultaneously possesses high thermal dimensional stability and high dimensional stability against moisture.

[0018] However, the problems to be solved by the present invention are not limited to those mentioned above, and those skilled in the art should be able to understand other problems not mentioned from the following description.

[0019] Methods for solving problems

[0020] To achieve the objectives described above, one aspect of the present invention provides a polyimide film having a coefficient of thermal expansion of 1 ppm / ℃ or higher and 5 ppm / ℃ or lower.

[0021] The elastic modulus is above 9 GPa and below 11.5 GPa.

[0022] The glass transition temperature is above 340℃ and below 400℃.

[0023] The hygroscopic expansion coefficient of the above-mentioned polyimide film can be above 4ppm / RH% and below 6ppm / RH%.

[0024] Another aspect of the present invention provides a polyimide film obtained by subjecting a polyamic acid solution containing an acid dianhydride component and a diamine component to an imidization reaction.

[0025] The aforementioned dianhydride component comprises two or more selected from the group consisting of biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA), oxydiphthalic anhydride (ODPA), and benzophenone tetracarboxylic dianhydride (BTDA); and the aforementioned diamine component comprises two or more selected from the group consisting of p-phenylenediamine (PPD), m-tolidine, diaminodiphenyl ether (ODA), and 1,3-diaminophenoxybenzene (TPE-R).

[0026] Based on a total diamine content of 100 mol%, the content of p-phenylenediamine is 10 mol% to 70 mol%, and the content of meta-toluidine is 25 mol% to 80 mol%.

[0027] Based on a total content of 100 mol% of the above-mentioned dianhydride components, the content of the above-mentioned biphenyl dianhydride can be more than 30 mol% and less than 60 mol%, and the content of the above-mentioned pyromellitic dianhydride can be more than 40 mol% and less than 60 mol%.

[0028] Furthermore, based on a total content of 100 mol% of the aforementioned dianhydride components, the content of the aforementioned oxydiphthalic anhydride may be 20 mol% or less, the content of the aforementioned benzophenone tetracarboxylic dianhydride may be 30 mol% or less, and based on a total content of 100 mol% of the aforementioned diamine components, the content of the aforementioned diaminodiphenyl ether (ODA) may be 20 mol% or less, and the content of the aforementioned 1,3-diaminophenoxybenzene may be 20 mol% or less.

[0029] The molar ratio of the above-mentioned p-phenylenediamine to the above-mentioned biphenyltetracarboxylic dianhydride can be 0.3 or more and 2.5 or less, and the molar ratio of the above-mentioned meta-toluidine to the above-mentioned pyromellitic dianhydride can be 0.6 or more and 1.5 or less.

[0030] In addition, the molar ratio of the above-mentioned p-phenylenediamine to the above-mentioned biphenyltetracarboxylic dianhydride can be 1.05 or more and 1.2 or less, and the molar ratio of the above-mentioned p-phenylenediamine and the above-mentioned meta-toluidine to the above-mentioned pyromellitic dianhydride can be 0.9 or more and 0.99 or less.

[0031] Another aspect of the present invention provides a method for manufacturing a polyimide film, comprising:

[0032] (a) A step of polymerizing an acid dianhydride component and a diamine component in an organic solvent to produce polyamic acid, wherein the acid dianhydride component comprises two or more selected from the group consisting of biphenyl dianhydride (BPDA), pyromellitic dianhydride (PMDA), oxydiphthalic anhydride (ODPA), and benzophenone tetracarboxylic dianhydride (BTDA), and the diamine component comprises two or more selected from the group consisting of p-phenylenediamine (PPD), m-tolidine, diaminodiphenyl ether (ODA), and 1,3-diaminophenoxybenzene (TPE-R); and

[0033] (b) The step of imidizing the above-mentioned polyamic acid.

[0034] Based on a total content of 100 mol% for the aforementioned dianhydrides, the content of the aforementioned biphenyltetracarboxylic dianhydride is between 30 mol% and 60 mol%, and the content of the aforementioned pyromellitic dianhydride is between 40 mol% and 60 mol%.

[0035] Based on a total diamine content of 100 mol%, the content of p-phenylenediamine is 10 mol% to 70 mol%, and the content of meta-toluidine is 25 mol% to 80 mol%.

[0036] Another aspect of the present invention provides a flexible metal foil laminate comprising the above-described polyimide film and a conductive metal foil.

[0037] Another aspect of the present invention provides an electronic component comprising the above-described flexible metal foil laminate.

[0038] Invention Effects

[0039] The present invention provides a polyimide film in which the composition ratio and reaction ratio of the acid dianhydride and diamine components are adjusted, thereby providing a polyimide film with excellent thermal dimensional stability and moisture dimensional stability.

[0040] Such polyimide films can be applied in a variety of fields where excellent dimensional stability is required, such as flexible metal foil laminates manufactured by metallization or electronic components containing such flexible metal foil laminates. Detailed Implementation

[0041] Best practice

[0042] 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.

[0043] Therefore, the embodiments described in this specification are only one of the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. It should be understood that at the time of filing this application, there may be many equivalents and modifications that can replace these embodiments.

[0044] In this specification, unless the context clearly specifies otherwise, singular expressions include plural expressions. It should be understood in this specification that terms such as “comprising,” “possessing,” or “having” are intended to specify the presence of a feature, number, step, constituent element, or combination thereof, and do not presuppose the presence or additional possibility of more than one other feature, number, step, constituent element, or combination thereof.

[0045] In this specification, “acid dianhydride” is intended to include its precursors or derivatives, which, although technically not acid dianhydrides, can still react with diamines to form polyamic acid, which can then be converted back into polyimide.

[0046] In this specification, "diamine" is intended to include its precursors or derivatives, which, although technically they may not be diamines, can still react with dianhydrides to form polyamic acid, which can then be converted back into polyimide.

[0047] In this specification, when quantities, concentrations, or other values ​​or parameters are given as a range, a preferred range, or a preferred upper limit and a preferred lower limit, it should be understood that any pair of ranges formed by any upper limit or preferred value and any lower limit or preferred value is specifically disclosed, regardless of whether the range is disclosed individually.

[0048] Where a range of values ​​is mentioned in this specification, unless otherwise stated, the range is intended to include the endpoints and all integers and fractions within that range. The scope of this invention is not intended to be limited to the specific values ​​mentioned when defining the range.

[0049] The polyimide film of one embodiment of the present invention is obtained by imidization reaction of a polyamic acid solution containing an acid dianhydride component and a diamine component. The acid dianhydride component comprises two or more selected from the group consisting of biphenyl dianhydride (BPDA), pyromellitic dianhydride (PMDA), oxydiphthalic anhydride (ODPA), and benzophenone tetracarboxylic dianhydride (BTDA). The diamine component comprises selected from p-phenylenediamine (PPD), m-toluidine, diaminodiphenyl ether (ODA), and 1... The composition comprises two or more of the following: 3-diaminophenoxybenzene (TPE-R), with the total content of the above-mentioned acid dianhydrides being 100 mol%, the content of the above-mentioned biphenyltetracarboxylic dianhydride being 30 mol% or more and 60 mol% or less, the content of the above-mentioned pyromellitictetracarboxylic dianhydride being 40 mol% or more and 60 mol% or less, with the total content of the above-mentioned diamines being 100 mol%, the content of the above-mentioned p-phenylenediamine being 10 mol% or more and 70 mol% or less, and the content of the above-mentioned meta-toluidine being 25 mol% or more and 80 mol% or less.

[0050] Preferably, based on a total content of 100 mol% of the above-mentioned dianhydride components, the content of the above-mentioned biphenyl dianhydride can be 30 mol% or more and 55 mol% or less, and the content of the above-mentioned pyromellitic dianhydride can be 45 mol% or more and 55 mol% or less.

[0051] In addition, preferably, based on a total content of 100 mol% of the diamine components, the content of p-phenylenediamine can be more than 15 mol% and less than 70 mol%.

[0052] In this invention, p-phenylenediamine is used as a rigid monomer. As the content of p-phenylenediamine increases, the synthesized polyimide will have a more linear structure, which helps to improve the mechanical properties of the polyimide.

[0053] In addition, meta-toluidine has a particularly hydrophobic methyl group, which contributes to the low moisture absorption properties of polyimide films related to moisture dimensional stability.

[0054] The polyimide chain of biphenyltetracarboxylic dianhydride from the present invention has a structure known as a charge transfer complex (CTC), which is a regular linear structure in which the electron donor and electron acceptor are close to each other, and the intermolecular interaction is enhanced.

[0055] This structure prevents the formation of hydrogen bonds with moisture, thus maximizing the effect of reducing the hygroscopicity of the polyimide film that affects the dimensional stability of moisture.

[0056] In addition, pyromellitic dianhydride is an acid dianhydride component with a relatively rigid structure, which can impart moderate elasticity to the polyimide film, making it a preferred choice from this perspective.

[0057] The ratio of dianhydride to biphenyl dianhydride is crucial for ensuring excellent dimensional stability of polyimide films. For example, as the ratio of biphenyl dianhydride decreases, the low moisture absorption rate expected from the aforementioned CTC structure becomes less desirable, and the dimensional stability of moisture content also declines.

[0058] In addition, biphenyl dianhydride contains two benzene rings corresponding to the aromatic moiety, while pyromellitic dianhydride contains one benzene ring corresponding to the aromatic moiety.

[0059] In the dianhydride component, when the molecular weight is the same, the increase in the content of pyromellitic dianhydride can be understood as an increase in the number of imide groups in the molecule. This can be understood as the ratio of imide groups from the aforementioned pyromellitic dianhydride in the polyimide polymer chain being relatively increased compared to the ratio of imide groups from biphenyl dianhydride.

[0060] That is, the increase in the content of pyromellitic dianhydride can also be regarded as a relative increase in the number of imide groups relative to the overall polyimide film, so it is difficult to expect high dimensional stability against moisture due to low moisture absorption.

[0061] Conversely, if the content of pyromellitic dianhydride is reduced, the rigid structure component is relatively reduced, and the elasticity of the polyimide film may decrease below the desired level.

[0062] For this reason, when the content of biphenyl dianhydride is higher than the above range or the content of pyromellitic dianhydride is lower than the above range, the dimensional stability of the polyimide film will decrease.

[0063] Conversely, if the content of biphenyl dianhydride is below the above range or the content of pyromellitic dianhydride is above the above range, it will also have an adverse effect on the dimensional stability of the polyimide film.

[0064] On the other hand, based on a total content of 100 mol% of the above-mentioned acid dianhydride components, the content of the above-mentioned oxydiphthalic anhydride may be 20 mol% or less, the content of the above-mentioned benzophenone tetracarboxylic dianhydride may be 30 mol% or less, based on a total content of 100 mol% of the above-mentioned diamine components, the content of the above-mentioned diaminodiphenyl ether (ODA) may be 20 mol% or less, and the content of the above-mentioned 1,3-diaminophenoxybenzene may be 20 mol% or less.

[0065] In the composition of the polyimide film described above, the molar ratio of p-phenylenediamine to biphenyltetracarboxylic dianhydride (=molar% of p-phenylenediamine / molar% of biphenyltetracarboxylic dianhydride) can be 0.3 or more and 2.5 or less, and the molar ratio of meta-toluidine to pyromellitic dianhydride (=molar% of meta-toluidine / molar% of pyromellitic dianhydride) can be 0.6 or more and 1.5 or less.

[0066] Furthermore, regarding the reaction molar ratio of the acid dianhydride component to the diamine component in the aforementioned polyimide film, the reaction molar ratio of the aforementioned p-phenylenediamine to the aforementioned biphenyltetracarboxylic dianhydride can be 1.05 or less to 1.2 or less, and the reaction molar ratio of the aforementioned p-phenylenediamine and the aforementioned meta-toluidine to the aforementioned pyromellitic dianhydride can be 0.9 or more to 0.99 or less.

[0067] That is, in the reaction process between the acid dianhydride component and the diamine component, 1 mole of biphenyltetracarboxylic dianhydride can react with more than 1.05 moles and less than 1.2 moles of p-phenylenediamine, and 1 mole of pyromellitic dianhydride can react with more than 0.9 moles and less than 0.99 moles of p-phenylenediamine and meta-toluidine.

[0068] Preferably, the molar ratio of the above-mentioned p-phenylenediamine and the above-mentioned meta-toluidine to the above-mentioned pyromellitic dianhydride can be 0.9 or more and 0.95 or less.

[0069] On the other hand, the coefficient of thermal expansion of the above-mentioned polyimide film can be above 1ppm / ℃ and below 5ppm / ℃, the elastic modulus can be above 9GPa and below 11.5GPa, and the coefficient of hygroscopic expansion can be above 4ppm / RH% and below 6ppm / RH%.

[0070] In addition, the glass transition temperature of the above-mentioned polyimide film can be above 340°C and below 400°C, preferably below 390°C.

[0071] In this invention, polyamic acid can be manufactured by the following methods:

[0072] (1) A method of polymerization in which all diamine components are added to a solvent and then acid dianhydride components are added in a manner that is substantially equal in molar to the diamine components;

[0073] (2) A method of polymerization in which all the acid dianhydride components are added to the solvent, and then the diamine components are added in a manner that is substantially equal in molar to the acid dianhydride components;

[0074] (3) After adding a portion of the diamine component to the solvent, a portion of the acid dianhydride component is mixed relative to the reaction component at a ratio of about 95 to 105 mol%, and then the remaining diamine component is added, followed by the remaining acid dianhydride component, so that the diamine component and the acid dianhydride component are polymerized in a substantially equimolar manner.

[0075] (4) After adding the acid dianhydride component to the solvent, a portion of the diamine compound is mixed relative to the reaction component at a ratio of about 95 to 105 mol%, then other acid dianhydride components are added, followed by the addition of the remaining diamine component, so that the diamine component and the acid dianhydride component are polymerized in a substantially equimolar manner.

[0076] (5) A method in which a portion of a diamine component and a portion of an acid dianhydride component are reacted in a solvent in excess of either component to form a first composition, and a portion of a diamine component and a portion of an acid dianhydride component are reacted in another solvent in excess of either component to form a second composition, and the first and second compositions are then mixed and polymerization is completed, wherein, in forming the first composition, if the diamine component is in excess, the acid dianhydride component is in excess in the second composition, and if the acid dianhydride component is in excess in the first composition, the diamine component is in excess in the second composition, thereby mixing the first and second compositions and polymerizing the total diamine component and the acid dianhydride component used in their reaction in a substantially equimolar manner; etc.

[0077] In one specific example, the method for manufacturing the polyimide film of the present invention may include:

[0078] (a) A step of polymerizing an acid dianhydride component and a diamine component in an organic solvent to produce polyamic acid, wherein the acid dianhydride component comprises two or more selected from the group consisting of biphenyl dianhydride (BPDA), pyromellitic dianhydride (PMDA), oxydiphthalic anhydride (ODPA), and benzophenone tetracarboxylic dianhydride (BTDA), and the diamine component comprises two or more selected from the group consisting of p-phenylenediamine (PPD), m-tolidine, diaminodiphenyl ether (ODA), and 1,3-diaminophenoxybenzene (TPE-R); and

[0079] (b) The step of imidizing the above-mentioned polyamic acid.

[0080] Based on a total content of 100 mol% for the aforementioned dianhydrides, the content of the aforementioned biphenyltetracarboxylic dianhydride is between 30 mol% and 60 mol%, and the content of the aforementioned pyromellitic dianhydride is between 40 mol% and 60 mol%.

[0081] Based on a total diamine content of 100 mol%, the content of p-phenylenediamine is 10 mol% to 70 mol%, and the content of meta-toluidine is 25 mol% to 80 mol%.

[0082] In this invention, the polymerization method of polyamic acid as described above can be defined by random polymerization. The polyimide film manufactured from the polyamic acid of this invention produced by the process described above can be preferably used to maximize the effect of this invention in improving dimensional stability.

[0083] However, the above-described polymerization method results in shorter repeating units within the polymer chain, which may limit the utilization of the various excellent properties of the polyimide chain derived from the dianhydride component. Therefore, block polymerization is a particularly preferred polymerization method for polyamic acid in this invention.

[0084] On the other hand, there are no particular limitations on the solvent used to synthesize polyamic acid; any solvent can be used as long as it dissolves polyamic acid, with amide-based solvents being preferred.

[0085] Specifically, the aforementioned organic solvent can be an organic polar solvent, more specifically, it can be an aprotic polar solvent, for example, it can be one or more selected from the group consisting of N,N-dimethylformamide (DMF), N,N-dimethylacetamide, N-methylpyrrolidone (NMP), γ-butyrolactone (GBL), and diethylene glycol dimethyl ether (Diglyme), but is not limited thereto, and can be used alone or in combination as needed.

[0086] In one example, the aforementioned organic solvents may particularly preferably be N,N-dimethylformamide and N,N-dimethylacetamide.

[0087] In addition, fillers can be added during the polyamic acid manufacturing process to improve various film properties such as lubricity, thermal conductivity, corona resistance, and loop hardness. There are no particular limitations on the fillers added; preferred examples include silica, titanium dioxide, alumina, silicon nitride, boron nitride, dicalcium phosphate, calcium phosphate, and mica.

[0088] The particle size of the filler is not particularly limited, but can be determined according to the desired membrane characteristics 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 particularly preferably 0.1 to 25 μm.

[0089] If the particle size is below the above range, it is not easy to show a modification effect; if it is above the above range, it may sometimes cause significant damage to the surface properties or a significant decrease in mechanical properties.

[0090] Furthermore, there is no particular limitation on the amount of filler added; it can be determined based on the desired membrane characteristics and filler particle size. Generally, the amount of filler added is 0.01 to 100 parts by weight relative to 100 parts by weight of polyimide, preferably 0.01 to 90 parts by weight, and more preferably 0.02 to 80 parts by weight.

[0091] If the filler content is below the above range, the modification effect brought about by the filler will not be easily observed; if it is above the above range, the mechanical properties of the membrane may be significantly damaged. There are no particular limitations on the method of adding the filler; any known method can be used.

[0092] In the manufacturing method of the present invention, the polyimide film can be manufactured by thermal imidization and chemical imidization.

[0093] Alternatively, it can be manufactured by a combined imidization method that combines thermal imidization and chemical imidization.

[0094] The aforementioned thermal imidization method is a method that eliminates chemical catalysts and uses heat sources such as hot air or infrared dryers to induce the imidization reaction.

[0095] In the above-described thermal imidization method, the gel membrane can be heat-treated at a variable temperature ranging from 100 to 600°C to imidize the amyl acid groups present in the gel membrane. More specifically, the heat treatment can be performed at 200 to 500°C, and more specifically, at 300 to 500°C to imidize the amyl acid groups present in the gel membrane.

[0096] However, a portion of the amic acid (about 0.1 mol% to 10 mol%) may also undergo imidization during the formation of the gel film. For this purpose, the polyamic acid composition can be dried at a variable temperature ranging from 50°C to 200°C, which also falls under the category of the above-mentioned thermal imidization method.

[0097] In the case of chemical imidization, polyimide films can be manufactured using dehydrating agents and imidizing agents in accordance with methods known in the art.

[0098] As an example of the composite imidization method, a dehydrating agent and an imidizing agent can be added to a polyamic acid solution, and then partially cured and dried by heating at 80 to 200°C, preferably at 100 to 180°C, and then heated at 200 to 400°C for 5 to 400 seconds, thereby producing a polyimide film.

[0099] The present invention provides a flexible metal foil laminate comprising the above-described polyimide film and a conductive metal foil.

[0100] The metal foil used is not particularly limited. When the flexible metal foil laminate of the present invention is used in electronic or electrical equipment applications, it may be, for example, a metal foil containing copper or copper alloy, stainless steel or its alloy, nickel or nickel alloy (including 42 alloy), aluminum or aluminum alloy.

[0101] In conventional flexible metal foil laminates, rolled copper foil or electrolytic copper foil is commonly used, and these types of copper foil are also preferred in this invention. Furthermore, the surface of these metal foils may be coated with an anti-rust layer, a heat-resistant layer, or an adhesive layer.

[0102] In this invention, the thickness of the metal foil is not particularly limited, as long as it is thick enough to perform its intended function.

[0103] The flexible metal foil laminate of the present invention can be a structure formed by laminating metal foil on at least one side of the above-mentioned polyimide film.

[0104] Implementation

[0105] The following describes the function and effects of the invention in more detail through specific manufacturing examples and embodiments. However, these manufacturing examples and embodiments are provided merely as illustrative examples of the invention, and the scope of the claims is not limited thereto.

[0106] Manufacturing example: Manufacturing of polyimide films

[0107] The polyimide film of the present invention can be manufactured by the following conventional methods known in the art. First, the above-mentioned acid dianhydride is reacted with the diamine component in an organic solvent to obtain a polyamic acid solution.

[0108] In this case, an aprotic solvent can typically be used, such as N,N'-dimethylformamide, N,N'-dimethylacetamide, N-methylpyrrolidone, or combinations thereof as an amide solvent.

[0109] Regarding the input form of the aforementioned acid dianhydride and diamine components, they can be added in powder, bulk, or solution form. It is preferred to add them in powder form at the initial stage of the reaction to carry out the reaction, and then add them in solution form to adjust the polymerization viscosity.

[0110] The obtained polyamic acid solution can be mixed with an imidization catalyst and a dehydrating agent and then coated onto a support.

[0111] Examples of catalysts used include tertiary amines (such as isoquinoline, β-methylpyridine, pyridine, etc.), and examples of dehydrating agents include acid anhydrides, but these are not limited to. Additionally, examples of supports used above include glass plates, aluminum plates, circulating stainless steel belts, or stainless steel rotating drums, but these are not limited to.

[0112] The film coated on the above-mentioned support gels on the support through drying air and heat treatment.

[0113] The gelled membrane was separated from the support and dried and imidized by heat treatment.

[0114] The membrane that has undergone the above heat treatment is then subjected to heat treatment under a certain tension, thereby removing the residual stress inside the membrane generated during the membrane formation process.

[0115] Specifically, 500 ml of DMF was added to a reactor equipped with a stirrer and nitrogen injection / exhaust pipe while nitrogen was being injected. After setting the reactor temperature to 30°C, biphenyl dianhydride (BPDA), pyromellitic dianhydride (PMDA), oxydiphthalic anhydride (ODPA), benzophenone tetracarboxylic dianhydride (BTDA), p-phenylenediamine (PPD), m-tolidine, diaminodiphenyl ether (ODA), and 1,3-diaminophenoxybenzene (TPE-R) were added according to the adjusted composition ratio and predetermined order, and allowed to completely dissolve. Then, under a nitrogen atmosphere, the reactor temperature was raised to 40°C and stirred continuously for 120 minutes, thereby producing polyamic acid with a primary reactive viscosity of 1,500 cP.

[0116] The polyamic acid thus produced is stirred until the final viscosity is 100,000 to 120,000 cP.

[0117] The contents of catalyst and dehydrating agent are adjusted and added to the prepared final polyamic acid, and then a polyimide film is manufactured using a coater.

[0118] Examples and Comparative Examples

[0119] As shown in Table 1 below, the contents of the acid dianhydride component and the diamine component in Examples 1 to 8 and Comparative Examples 1 to 7 were adjusted to manufacture polyimide films according to the manufacturing example.

[0120] In addition, the reaction was adjusted so that the molar ratio of p-phenylenediamine to biphenyltetracarboxylic dianhydride in Examples 1 to 7 was 1.05 or more and 1.2 or less, and the molar ratio of p-phenylenediamine and the above-mentioned meta-toluidine to pyromellitic dianhydride was 0.9 or more and 0.99 or less.

[0121] [Table 1]

[0122]

[0123] The elastic modulus, coefficient of thermal expansion (CTE), coefficient of hydroscopic expansion (CHE), and glass transition temperature (Tg) of the manufactured polyimide film were determined and are shown in Table 2 below.

[0124] [Table 2]

[0125]

[0126] (1) Determination of elastic modulus

[0127] The elastic modulus of the polyimide films manufactured in all examples and comparative examples was the average value after three tests using the Standard Instron testing apparatus according to ASTM D882.

[0128] (2) Determination of thermal expansion coefficient

[0129] The coefficient of thermal expansion (CTE) was determined as follows: A TA thermomechanical analyzer Q400 was used. The polyimide film was cut into pieces with a width of 4 mm and a length of 20 mm. A tension of 0.05 N was applied under a nitrogen atmosphere, and the temperature was increased from room temperature to 400 °C at a rate of 10 °C / min. Then, it was cooled again at a rate of 10 °C / min. The slope in the range of 50 °C to 200 °C was measured.

[0130] (3) Determination of hygroscopic expansion coefficient

[0131] The hygroscopic expansion coefficient (CHE) was determined as follows: Under the condition of applying a minimal load (approximately 1 g relative to a 25 mm × 150 mm sample) without loosening the polyimide film, the humidity was adjusted to 3% RH, and the film was allowed to absorb moisture until it was fully saturated and the dimensions were measured. Then, the humidity was adjusted to 90% RH, and the film was similarly allowed to absorb moisture and the dimensions were measured. Based on the results of both tests, the dimensional change rate at a relative humidity of 90% RH with a relative humidity difference of 87% was determined.

[0132] (4) Glass transition temperature determination

[0133] Glass transition temperature (T) g The method uses DMA to determine the loss modulus and storage modulus of each film, and uses the inflection point in their tangent diagram as the glass transition temperature.

[0134] The test results showed that the polyimide films of Examples 1 to 8 exhibited the following characteristics: a coefficient of thermal expansion of 1 ppm / ℃ or more and 5 ppm / ℃ or less, an elastic modulus of 9 GPa or more and 11.5 GPa or less, and a coefficient of hygroscopic expansion of 4 ppm / RH% or more and 6 ppm / RH% or less.

[0135] In contrast, in Comparative Examples 1 and 2, which contained little or no meta-toluidine (15% by weight), although the coefficient of thermal expansion was superior (below 1.5 ppm / °C), the measured coefficient of hygroscopic expansion was above 6.5 ppm / RH%, and the moisture dimensional stability was low compared to the Examples.

[0136] On the other hand, it can be confirmed that the elastic modulus of Comparative Example 7, which uses a small amount of meta-toluidine (15% by weight) as a diamine component, as well as diaminodiphenyl ether and p-phenylenediamine, is reduced to less than 9 GPa.

[0137] In addition, in the cases of Comparative Examples 2 to 4, it was confirmed that the glass transition temperature was lower or higher than that of the Examples.

[0138] Furthermore, in Comparative Examples 3 and 4, which contained excessive amounts of meta-toluidine, it was found that although the hygroscopic expansion coefficient characteristics were superior (below 5.9 ppm / RH%), the measured thermal expansion coefficient was above 5.7 ppm / ℃, and the thermal dimensional stability was low compared to the Examples.

[0139] On the other hand, it can be confirmed that, compared with the examples, Comparative Example 5, which contains oxydiphthalic anhydride as an acid dianhydride while containing an excessive amount of meta-toluidine, has reduced thermal dimensional stability and a lower glass transition temperature (thermal expansion coefficient: 7.0 ppm / ℃, glass transition temperature: 300℃).

[0140] It can be confirmed that, compared with the examples, Comparative Example 6, which contains 1,3-diaminophenoxybenzene as a diamine component while containing an excessive amount of meta-toluidine, has an excessively increased elastic modulus (elastic modulus: 12.2 GPa) and a lower glass transition temperature (glass transition temperature: 310°C).

[0141] Therefore, it can be confirmed that the polyimide films of Examples 1 to 8 manufactured within the appropriate scope of this application have excellent thermal dimensional stability and moisture dimensional stability, but it is difficult to achieve both thermal dimensional stability and moisture dimensional stability outside the appropriate scope of this application.

[0142] Furthermore, it can be confirmed that the polyimide films of Examples 1 to 8 manufactured within the appropriate scope of this application have elastic modulus and glass transition temperature suitable for application in various fields.

[0143] That is, it can be confirmed that the polyimide film that has excellent dimensional stability and is suitable for various application fields and fully meets various conditions is the polyimide film manufactured within the appropriate scope of this application.

[0144] The embodiments of the polyimide film and the method for manufacturing the polyimide film of the present invention are merely preferred embodiments that enable those skilled in the art to readily implement the present invention, and are not limited to the above embodiments, and therefore do not limit the scope of the claims of the present invention. Therefore, the true scope of protection of the present invention will be defined by the technical concept of the appended claims. Furthermore, it will be apparent to those skilled in the art that various substitutions, modifications, and alterations can be made without departing from the technical concept of the present invention, and of course, the parts that can be easily modified by those skilled in the art also fall within the scope of the claims of the present invention.

[0145] Industrial availability

[0146] The present invention provides a polyimide film in which the composition ratio and reaction ratio of acid dianhydride and diamine are adjusted, thereby providing a polyimide film with excellent thermal dimensional stability and moisture dimensional stability.

[0147] Such polyimide films can be applied in a variety of fields where excellent dimensional stability is required, such as flexible metal foil laminates manufactured by metallization or electronic components containing such flexible metal foil laminates.

Claims

1. A polyimide film having a coefficient of thermal expansion of 1 ppm / ℃ or higher and 5 ppm / ℃ or lower. The elastic modulus is above 9 GPa and below 11.5 GPa. The glass transition temperature is above 340℃ and below 400℃. The polyimide film is obtained by an imidization reaction of a polyamic acid solution containing an acid dianhydride component and a diamine component, wherein the acid dianhydride component comprises biphenyltetracarboxylic dianhydride (BPDA) and the diamine component comprises p-phenylenediamine (PPD). The molar ratio of p-phenylenediamine (PPD) to biphenyl dianhydride (BPDA) is 1.05 to 1.

2. The dianhydride component further comprises at least one selected from the group consisting of pyromellitic dianhydride (PMDA), oxydiphthalic anhydride (ODPA), and benzophenone dianhydride (BTDA). The diamine component further comprises at least one selected from the group consisting of meta-toluidine, diaminodiphenyl ether (ODA), and 1,3-diaminophenoxybenzene (TPE-R). Based on a total diamine content of 100 mol%, the content of p-phenylenediamine is 10 mol% to 70 mol%, the content of meta-toluidine is 25 mol% to 80 mol%, and... Based on a total content of 100 mol% of the dianhydride components, the content of the biphenyltetracarboxylic dianhydride is between 30 mol% and 60 mol%, and the content of the pyromellitic dianhydride is between 40 mol% and 60 mol%.

2. The polyimide film according to claim 1 has a moisture absorption expansion coefficient of 4ppm / RH% or higher and 6ppm / RH% or lower.

3. The polyimide film according to claim 1, Based on a total dianhydride content of 100 mol%, the content of the oxydiphthalic anhydride is less than 20 mol%, and the content of the benzophenone tetracarboxylic dianhydride is less than 30 mol%. Based on a total content of 100 mol% for the diamine component, the content of the diaminodiphenyl ether (ODA) is less than 20 mol%, and the content of the 1,3-diaminophenoxybenzene is less than 20 mol%.

4. The polyimide film according to claim 1, wherein the molar ratio of p-phenylenediamine to biphenyltetracarboxylic dianhydride is 0.3 or more and 2.5 or less.

5. The polyimide film according to claim 1, wherein the molar ratio of meta-toluidine to pyromellitic dianhydride is 0.6 or more and 1.5 or less.

6. The polyimide film according to claim 1, wherein the molar ratio of the p-phenylenediamine and the meta-toluidine to the pyromellitic dianhydride is 0.9 or more and 0.99 or less.

7. A method for manufacturing a polyimide film, comprising: (a) A step of polymerizing an acid dianhydride component and a diamine component in an organic solvent to produce polyamic acid, wherein the acid dianhydride component comprises two or more selected from the group consisting of biphenyl dianhydride (BPDA), pyromellitic dianhydride (PMDA), oxydiphthalic anhydride (ODPA), and benzophenone tetracarboxylic dianhydride (BTDA), and the diamine component comprises two or more selected from the group consisting of p-phenylenediamine (PPD), meta-toluidine, diaminodiphenyl ether (ODA), and 1,3-diaminophenoxybenzene (TPE-R); and (b) The step of imidizing the polyamic acid. Based on a total dianhydride content of 100 mol%, the content of biphenyl dianhydride is between 30 mol% and 60 mol%, and the content of pyromellitic dianhydride is between 40 mol% and 60 mol%. Based on a total diamine content of 100 mol%, the content of p-phenylenediamine is between 10 mol% and 70 mol%, and the content of meta-toluidine is between 25 mol% and 80 mol%. The molar ratio of p-phenylenediamine to biphenyltetracarboxylic dianhydride is 1.05 to 1.

2.

8. The method for manufacturing the polyimide film according to claim 7, Based on a total dianhydride content of 100 mol%, the content of the oxydiphthalic anhydride is less than 20 mol%, and the content of the benzophenone tetracarboxylic dianhydride is less than 30 mol%. Based on a total content of 100 mol% for the diamine component, the content of the diaminodiphenyl ether (ODA) is less than 20 mol%, and the content of the 1,3-diaminophenoxybenzene is less than 20 mol%.

9. In the method for manufacturing the polyimide film according to claim 7, the molar ratio of the p-phenylenediamine and the meta-toluidine to the pyromellitic dianhydride is 0.9 or more and 0.99 or less.

10. The method for manufacturing a polyimide film according to claim 7, wherein the polyimide film has a coefficient of thermal expansion of 1 ppm / ℃ or higher and 5 ppm / ℃ or lower, an elastic modulus of 9 GPa or higher and 11.5 GPa or lower, a glass transition temperature of 340℃ or higher and 400℃ or lower, and a coefficient of hygroscopic expansion of 4 ppm / RH% or higher and 6 ppm / RH% or lower.

11. A flexible metal foil laminate comprising a polyimide film according to any one of claims 1 to 6 and a conductive metal foil.

12. An electronic component comprising the flexible metal foil laminate of claim 11.

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