TWI853231B - Composition for manufacturing polyimide film and polyimide film for flexible metal clad laminate manufactured using the same - Google Patents

Abstract

The present invention relates to a composition for manufacturing a polyimide film, and a polyimide film for a flexible metal foil laminate manufactured using the composition. According to one embodiment of the present invention, a composition for manufacturing a polyimide film is provided, which comprises an aromatic dianhydride, a diamine, and a curing catalyst, wherein the curing catalyst comprises at least one selected from the group consisting of imidazole compounds, quinolinone compounds, and quinoline compounds.

Description

Composition for producing polyimide film, and polyimide film for flexible metal foil laminate produced using the same

The present invention relates to a composition for preparing a polyimide film and a polyimide film for a flexible metal foil laminate prepared by using the composition.

Flexible Printed Circuit Board (FPCB) is used when a flexible thin circuit board is required. In recent years, with the trend of miniaturization, high speed and functional integration of electronic equipment, the requirements for high transmission, lightness, ultra-thinness and miniaturization have been increasing. Therefore, it is necessary to develop FPCB materials accordingly.

Currently, display panel manufacturers are constantly trying to reduce the bezel. One method is to fold the FPCB at the edge of the display panel to reduce the bezel.

However, when this method is used, the bonding area is reduced because the FPCB at the edge of the display panel is bent backward, and the bonding portion may come off due to the repellency of the circuit material.

Figure 1 shows a method of reducing the display frame by folding the FPCB at the edge of the display panel backward. When the FPCB at the edge of the panel is folded backward, the bonding area of the FPCB is reduced, and eventually the bonding part will be separated due to the repulsion of the circuit.

For this reason, a Flexible Metal Clad Laminate (FMCL) material with high bendability and low repellency is needed, which can adhere well even when the bonding area is minimized.

However, polyimide as an insulating layer material for flexible metal foil laminates generally has a structure with high dimensional stability but high repellency.

Therefore, it is necessary to produce a polyimide film that can simultaneously achieve high bendability, low repellency, and dimensional stability.

The above background technology is owned or obtained by the inventor in the process of deriving the disclosure content of this application, and is not necessarily known technology disclosed to the public before this application.

Technical issues to be solved

The purpose of the present invention is to solve the above problems and provide a composition for manufacturing a polyimide film, and a polyimide film and a flexible metal foil laminate manufactured using the composition, which can simultaneously improve the bendability, heat resistance, dimensional stability and repellency of the polyimide film.

However, the technical problems to be solved by the present invention are not limited to the above-mentioned topics, and other topics not mentioned will be clearly understood by ordinary technicians in this field through the following description.

Technical solutions to the problem

One embodiment of the present invention provides a composition for manufacturing a polyimide film, comprising: an aromatic dianhydride, a diamine, and a curing catalyst, wherein the curing catalyst comprises at least one selected from the group consisting of imidazole compounds, quinolinone compounds, and quinoline compounds.

In one embodiment, the aromatic dianhydride may include one or more selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), bisphenol A dianhydride (BPADA), and 4,4′-(hexafluoroisopropylene) diphthalic anhydride (6FDA).

In one embodiment, the diamine may include: a first diamine including p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), or both; a second diamine including 4,4′-diaminodiphenyl ether (ODA), 4,4′-diaminodiphenylmethane (MDA), or both; and a third diamine including 2-(4-aminophenyl)-5-aminobenzimidazole (PBI).

In one embodiment, the third diamine may be included in an amount of 1 mol % to 30 mol % relative to the total content of the diamine.

In one embodiment, the diamine may be present in an amount of 10 to 200 parts by weight relative to 100 parts by weight of the aromatic dianhydride.

In one embodiment, the curing catalyst may be 5 to 40 parts by weight relative to 100 parts by weight of the total content of the aromatic dianhydride and the diamine.

In one embodiment, the imidazole compound may include one or more selected from the group consisting of imidazole, benzimidazole, 1-methylimidazole, 1-(trimethylsilyl)-imidazole, 1,2-dimethylimidazole, 1-(3-aminopropyl)-imidazole, 2-alkylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, and 3-phenylimidazole.

In one embodiment, the quinolinone compound may include one or more selected from the group consisting of quinolinone, 1,2-dihydro-2,2,4-trimethylquinolinone, 2-chloro-3-(chloromethyl)quinolinone, 4-(4-dimethylaminostyryl)quinolinone, and 6-(aminomethyl)quinolinone.

In one embodiment, the quinoline compound may include at least one selected from the group consisting of quinoline, isoquinoline, and benzoquinoline.

In one embodiment, the composition for preparing a polyimide film may have a solid content of 5 wt % to 20 wt % and a viscosity of 10,000 cP to 30,000 cP.

Another embodiment of the present invention provides a method for preparing a composition for manufacturing a polyimide film, comprising the following steps: dissolving a diamine in an organic solvent to prepare a diamine solution; and adding an aromatic dianhydride and a curing catalyst to the diamine solution, wherein the curing catalyst comprises one or more selected from the group consisting of imidazole compounds, quinolinone compounds, and quinoline compounds.

Another embodiment of the present invention provides a polyimide film for a flexible metal foil laminate, which is made of a composition for making a polyimide film including an aromatic dianhydride, a diamine, and a curing catalyst, and has a Young’s modulus of less than 5 GPa and a coefficient of thermal expansion (CTE) of less than 15 ppm/K.

In one embodiment, the polyimide film for the flexible metal foil laminate, when attached to a coverlay, can be bent more than 10,000 times in an MIT folding test using the JIS C 6471 method.

In one embodiment, the dimensional change rate of the polyimide film used for the flexible metal foil laminate is less than 0.1% after heat treatment at 150°C for 30 minutes, and the dimensional change rate is calculated by the following formula 1: [Formula 1] Dimensional change rate (%) = {(average pore distance after heat treatment - average pore distance before heat treatment)/average pore distance before heat treatment} x 100.

In one embodiment, the stiffness of the polyimide film used for the flexible metal foil laminate may be 1.0 N/m to 1.7 N/m.

According to another embodiment of the present invention, a flexible metal foil laminate is provided, comprising: a metal foil; and a polyimide film laminated on one or both sides of the metal foil.

In one embodiment, the metal foil may include at least one selected from the group consisting of rolled copper foil (RA, Roo-Annealed), electrolytic copper foil (ED, electrodeposition), aluminum foil (Aluminum Foil), and nickel foil (Nickel Foil).

Invention Effect

The composition for manufacturing a polyimide film according to the present invention has the effects of improving the bendability, heat resistance, dimensional stability and repellency of the polyimide film.

Furthermore, the polyimide film according to the present invention has high flexibility, high dimensional stability and low repellency, and still has excellent adhesion when the bonding area is reduced.

Furthermore, the flexible metal foil laminate according to the present invention is also suitable for use as a raw material for FPCB and can be used to minimize the bezel.

The following will describe the implementation in detail with reference to the attached drawings. It should be understood that the implementation can be modified in many ways, and the scope of the present application is not limited to the following implementation. All modifications to the implementation, their equivalents and even their substitutes are within the scope of the present invention.

The terms used in the embodiments are not intended to limit the present invention but are for illustrative purposes only. In the absence of special instructions in the content, singular expressions include plural meanings. In this specification, terms such as "including" or "having" are used to express the existence of features, numbers, steps, operations, constituent elements, accessories or combinations thereof described in the specification, and do not exclude the possibility of the existence or additional addition of one or more other features, numbers, steps, operations, constituent elements, accessories or combinations thereof.

In the absence of other definitions, all terms used in this document, including technical or scientific terms, have the usual meanings understood by ordinary technicians in this field. Commonly used terms as defined in dictionaries should be understood as the meanings in the relevant technical content, and should not be interpreted as idealized or overly formalized meanings if not clearly defined in this specification.

Furthermore, in the process of describing with reference to the drawings, the same components are labeled with the same drawings, and repeated descriptions are omitted. In the process of describing the implementation, when it is determined that the specific description of the related known technology will unnecessarily confuse the implementation, the detailed description is omitted.

Furthermore, when describing the components of the embodiments with reference to the accompanying drawings, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only used to distinguish one component from other components and are not used to limit the nature or order of the corresponding components. When the specification states that a component is "connected", "coupled" or "contacting" another component, a third component may be "connected", "coupled" or "contacting" between the first component and the second component, although the first component can be directly connected, coupled or contacting the second component.

When a component has the same function as a component of a certain embodiment, the component is described in the other embodiments using the same name. If the description of a certain embodiment is applicable to other embodiments without mentioning a counterexample, the repeated description is omitted.

One embodiment of the present invention provides a composition for manufacturing a polyimide film, comprising an aromatic dianhydride; a diamine; and a curing catalyst, wherein the curing catalyst comprises at least one selected from the group consisting of imidazole compounds, quinolinone compounds, and quinoline compounds.

The composition for manufacturing a polyimide film according to the present invention comprises an aromatic dianhydride, a diamine and a curing catalyst, and has the effects of achieving heat resistance, dimensional stability, bendability, and low repellency of the polyimide film.

The composition for producing a polyimide film according to the present invention includes an aromatic dianhydride.

The aromatic dianhydride has the characteristics of improving the heat resistance and dimensional stability of the polyimide film.

In one embodiment, the aromatic dianhydride may include one or more selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), bisphenol A dianhydride (BPADA), and 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA).

In one embodiment, the aromatic dianhydride may include: a first aromatic dianhydride including pyromellitic dianhydride (PMDA); and a second aromatic dianhydride including biphenyltetracarboxylic dianhydride (BPDA).

In one embodiment, the content of the second aromatic dianhydride is 10 mol to 500 mol, preferably 40 mol to 400 mol, relative to 100 mol of the first aromatic dianhydride.

In one embodiment, the molar ratio of the first aromatic dianhydride to the second aromatic dianhydride may be 9:1 to 1:9, preferably 8:2 to 2:8, and more preferably 7:3 to 3:7.

In one embodiment, the composition for manufacturing the polyimide film includes two or more aromatic dianhydrides at a predetermined molar ratio, which can more effectively improve the heat resistance and dimensional stability of the polyimide film.

The composition for producing a polyimide film according to the present invention includes a diamine.

The diamine has the characteristics of being able to realize the bendability, low repellency, and dimensional stability of the polyimide film.

In one embodiment, the diamine may include: a first diamine including p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), or both of the foregoing; a second diamine including 4,4'-diaminodiphenyl ether (ODA), 4,4'-diaminodiphenylmethane (MDA), or both of the foregoing; and a third diamine including 2-(4-aminophenyl)-5-aminobenzimidazole (PBI).

In one embodiment, the third diamine is 1 mol % to 30 mol % relative to the total content of the diamine.

Preferably, relative to the total content of the diamine, the third diamine may be 5 mol % to 20 mol %, more preferably 5 mol % to 15 mol %.

The third diamine includes imidazole diamine, which plays a key role in achieving low repellency and dimensional stability of the polyimide film.

When the content of the third diamine is lower than the above range, the coefficient of thermal expansion (CTE) increases and the dimensional stability decreases. When the content exceeds the above range, the coefficient of thermal expansion (CTE) decreases excessively and the difference between the coefficient of thermal expansion of the metal foil increases, thereby reducing the dimensional stability.

In one embodiment, the diamine may include 10 to 50 mol of the second diamine and 1 to 30 mol of the third diamine relative to 100 mol of the first diamine.

Preferably, the diamine may include 10 to 40 moles of the second diamine and 5 to 30 moles of the third diamine relative to 100 moles of the first diamine. More preferably, the diamine may include 20 to 40 moles of the second diamine and 10 to 20 moles of the third diamine relative to 100 moles of the first diamine.

In one embodiment, for the diamine, the molar ratio of the first diamine to the second diamine may be 9:1 to 1:1, preferably 8:1 to 7:2.

In one embodiment, for the diamine, the molar ratio of the first diamine to the third diamine may be 9:1 to 1:1, preferably 9:1 to 7:1.

In one embodiment, for the diamine, the molar ratio of the second diamine to the third diamine can be 3:1 to 1:1, preferably 3:1 to 2:1.

In one embodiment, the composition for manufacturing the polyimide film includes three or more diamines at a predetermined molar ratio, which has the effect of achieving low repellency, bendability, and dimensional stability of the polyimide film at the same time.

In one embodiment, the diamine may further include one or more selected from the group consisting of: 2-(4-aminophenyl)benzo[di]oxazol-5-amine (PBO), 2,5-diaminotoluene, 2,6-diaminotoluene, 1,3-bis(4,4'-aminophenoxy)benzene, 4,4'-diamino-1,5-phenoxypentane, 4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 2,2'-diaminodiphenylpropane, bis(3,5-diethyl-4-aminophenyl)methane, diaminodiphenylsulfone, diaminobenzophenone, diaminonaphthalene, 1,4-bis(4-amino 1,4-Bis(4-aminophenyl)benzene, 9,10-Bis(4-aminophenyl)anthracene, 1,3-Bis(4-aminophenoxy)benzene, 4,4'-Bis(4-aminophenoxy)diphenylsulfone, 2,2-Bis[4-(4-aminophenoxy)phenyl]propane, 2,2'-trifluoromethyl-4,4'-diaminobiphenyl, 1,4-diaminocyclohexane, 1 , 4-cyclohexanebis(methylamine), 4,4'-diaminodicyclohexylmethane (MCA), 4,4'-methylenebis(2-methylcyclohexylamine) (MMCA), ethylenediamine (EN), 1,3-diaminopropane (13DAP), tetramethylenediamine, 1,6-hexamethylenediamine (16DAH), and 1,12-diaminododecane (112DAD).

In one embodiment, the diamine may be present in an amount of 10 to 200 parts by weight relative to 100 parts by weight of the aromatic dianhydride.

Preferably, relative to 100 parts by weight of the aromatic dianhydride, the diamine may be 50 parts by weight to 150 parts by weight, more preferably, relative to 100 parts by weight of the aromatic dianhydride, the diamine may be 80 parts by weight to 120 parts by weight. Most preferably, relative to 100 parts by weight of the aromatic dianhydride, the diamine is 100 parts by weight, that is, the ratio of the aromatic dianhydride to the diamine is 1:1.

In one embodiment, the content ratio of the aromatic dianhydride: the diamine can be 1:10 to 10:1, preferably 1:5 to 5:1, and more preferably 1:2 to 2:1.

The composition for manufacturing a polyimide film according to the present invention comprises a curing catalyst, wherein the curing catalyst comprises at least one selected from the group consisting of imidazole compounds, quinolinone compounds, and quinoline compounds.

The curing catalyst can reduce the resistance of the polyimide film, thereby improving the bending resistance and dimensional stability.

In one embodiment, the curing catalyst may be 5 to 40 parts by weight relative to 100 parts by weight of the total content of the aromatic dianhydride and the diamine.

Preferably, the curing catalyst may be 5 to 30 parts by weight relative to 100 parts by weight of the total content of the aromatic dianhydride and the diamine.

The total content is the sum of the content of the aromatic dianhydride and the content of the diamine.

When the content of the curing catalyst is below the range, the tensile strength and dimensional stability are reduced and the repellency is increased.

On the contrary, when the content of the curing catalyst exceeds the range, the bending resistance may be reduced.

In particular, the content of the curing catalyst is a key factor in adjusting the physical properties of the polyimide film.

In one embodiment, the imidazole compound may include one or more selected from the group consisting of imidazole, benzimidazole, 1-methylimidazole, 1-(trimethylsilyl)-imidazole, 1,2-dimethylimidazole, 1-(3-aminopropyl)-imidazole, 2-alkylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, and 3-phenylimidazole.

In one embodiment, the quinolinone compound includes one or more selected from the group consisting of quinolinone, 1,2-dihydro-2,2,4-trimethylquinolinone, 2-chloro-3-(chloromethyl)quinolinone, 4-(4-dimethylaminostyryl)quinolinone, and 6-(aminomethyl)quinolinone.

In one embodiment, the quinoline compound includes at least one selected from the group consisting of quinoline, isoquinoline, and benzoquinoline.

In one embodiment, the composition for preparing a polyimide film has a solid content of 5 wt % to 20 wt % and a viscosity of 10,000 cps to 30,000 cps.

Preferably, the solid content of the composition for manufacturing a polyimide film may be 8 wt % to 15 wt %.

The solid content range is the solid content range when the composition used to manufacture the polyimide film is polyamide, which can be considered based on the molecular weight (polymerization degree) suitable for forming the polyimide film and the workability (viscosity) when applied on one side of the metal foil.

Furthermore, the viscosity of the composition for manufacturing the polyimide film may be 10,000 to 30,000 centipoise, which may take workability during coating into consideration.

When the viscosity of the composition for manufacturing the polyimide film is less than the above range, the solution will easily flow down when applied on one side of the metal foil; when it exceeds the above range, the solution will condense during application, resulting in the inability to evenly apply the surface.

The composition for producing a polyimide film according to the present invention may further include an organic solvent.

In one embodiment, the organic solvent may include one or more selected from the group consisting of N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethyl sulfoxide (DMSO), tetrahydrofuran (TFH), benzene, cresol, hexane, cyclohexane, chloroform, phenol, and halogenated phenols.

Preferably, the organic solvent may include one or more selected from the group consisting of N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

Another embodiment of the present invention provides a method for preparing a composition for manufacturing a polyimide film, comprising the following steps: dissolving a diamine in an organic solvent to prepare a diamine solution; and adding an aromatic dianhydride and a curing catalyst to the diamine solution, wherein the curing catalyst comprises one or more selected from the group consisting of imidazole compounds, quinolinone compounds, and quinoline compounds.

The characteristics of the organic solvent, the diamine, the aromatic dianhydride, and the curing catalyst are the same as those described above.

Another embodiment of the present invention is to use a composition for manufacturing polyimide films including aromatic dianhydride, diamine, and curing catalyst to manufacture a polyimide film for flexible metal foil laminates, wherein the Young’s modulus is below 5 GPa and the coefficient of thermal expansion (CTE) is below 15 ppm/K.

The polyimide film of the present invention controls the Young’s modulus below 5 GPa to reduce stiffness, thereby having the characteristics of low repellency and high flexibility. This also has an effect on improving the MIT folding endurance.

The polyimide film of the present invention controls the coefficient of thermal expansion (CTE) to below 15 ppm/K, thereby improving the dimensional stability of the flexible metal foil laminate.

The coefficient of thermal expansion (CTE) is measured in the temperature range of 100°C to 250°C using a film with a thickness of 20 μm.

In one embodiment, the polyimide film for the flexible metal foil laminate is bent more than 10,000 times in the MIT folding test using the JIS C 6471 method when the coverlay is attached.

In one implementation, the number of bends may be greater than 13,000.

The polyimide film for the flexible metal foil laminate according to the present invention has excellent MIT folding endurance, that is, excellent bending resistance.

The coverlay may be formed of polyimide with a thickness of 12.5 microns and an adhesive with a thickness of 15 microns.

This is to replicate the Flexible Printed Circuit Board (FPCB) and reduce the test deviation.

In one embodiment, after the polyimide film used for the flexible metal foil laminate is heat treated at 150°C for 30 minutes, the dimensional change rate is measured to be less than 0.1%, and the dimensional change rate is calculated according to the following formula 1. [Formula 1] Dimensional change rate (%) = {(average pore distance after heat treatment - average pore distance before heat treatment)/average pore distance before heat treatment} x 100

The dimensional change rate includes both the dimensional change rate in the MD direction and the dimensional change rate in the TD direction.

In one embodiment, the dimensional change rate in the MD direction may be less than 0.06%, and the dimensional change rate in the TD direction may be less than 0.05%.

In one embodiment, the stiffness of the polyimide film used for the flexible metal foil laminate may be 1.0 N/m to 1.7 N/m.

Preferably, the stiffness of the polyimide film used for the flexible metal foil laminate may be 1.4 N/m to 1.7 N/m.

The polyimide film for the flexible metal foil laminate according to the present invention has low rigidity and thus has characteristics of low resistance and modulus.

The polyimide film for a flexible metal foil laminate according to the present invention can reduce repellency while ensuring excellent dimensional stability, so it can be deformed according to various requirements and maintain adhesion properties even when the contact area with other materials is reduced.

For example, even if the FPCB bonding area at the edge of the display panel is reduced due to a reduction in the area of the display terminal portion for various reasons, the bonding portion can be prevented from falling off by reducing the repellency of the polyimide film layer.

Another embodiment of the present invention provides a flexible metal foil laminate, comprising a metal foil; and the polyimide film laminated to one or both sides of the metal foil.

FIG. 2 is a diagram showing a cross section of a flexible metal foil laminate according to an embodiment of the present invention.

2 , the composition for making polyimide is coated once or multiple times on one or both sides of a metal foil and laminated to form a polyimide film layer.

According to one embodiment, the polyimide film is laminated by coating the composition for producing the polyimide film of the present invention on one or both sides of the metal foil.

The coating may be performed by slot die coating, comma coating, reverse comma coating, cast coating, or dip coating.

The coating process can be performed multiple times, and a drying process can be performed after coating. The drying process is performed at a temperature range of 100°C to 200°C for 1 minute to 20 minutes, and the temperature is maintained at the highest temperature for 1 minute to 8 minutes before cooling.

According to one embodiment, the polyimide film is cured after coating.

The curing is carried out in a nitrogen atmosphere, and can be performed at a temperature range of 300°C to 400°C for 5 to 60 minutes, and maintained at the highest temperature for 1 to 15 minutes before cooling. At this time, the highest temperature can be reached by continuously increasing the temperature for 5 to 30 minutes.

In one embodiment, the metal foil may include one or more selected from the group consisting of rolled copper foil (RA, Roo-Annealed), electrolytic copper foil (ED, electrodeposition), aluminum foil (Aluminum Foil), and nickel foil (Nickel Foil).

As an example, the flexible metal foil laminate may be a flexible copper clad laminate (FCCL).

In one embodiment, the thickness of the polyimide film may be 5 μm to 100 μm.

The present invention is described in more detail below through embodiments and comparative examples.

However, the following embodiments are only used to illustrate the present invention, and the content of the present invention is not limited to the following embodiments.

＜ Embodiment ＞ Preparation of compositions for making polyimide films and flexible metal foil laminates

1 ） Preparation of a composition for making a polyimide film

After dissolving the diamine in an organic solvent, the aromatic dianhydride is mixed with a curing catalyst to prepare a composition for manufacturing a polyimide film.

2 ) Manufacturing of flexible metal foil laminates

The prepared composition for manufacturing a polyimide film is coated on one side of a metal foil and dried at a temperature ranging from 100°C to 200°C for 10 minutes to 20 minutes.

The dried laminate is then cured in a UV-heated continuous curing machine at temperatures ranging from 300°C to 400°C.

At this time, nitrogen is supplied to the curing machine, and the temperature is raised from room temperature to 300°C to 400°C within 30 minutes, maintained at the highest temperature for less than 10 minutes, and then cooled.

The thickness of the polyimide film is 7.5 microns to 50 microns.

＜ Comparison Example ＞ Preparation of compositions for making polyimide films and flexible metal foil laminates

When preparing a composition for preparing a polyimide film, the composition for preparing a polyimide film is prepared in the same manner as in Example 1, except that a curing catalyst is not used and a dianhydride and two diamines are used, and a flexible metal foil laminate is manufactured.

The specific composition of the embodiments and comparative examples is shown in Table 1.

[Table 1] Anhydride content (mol%) Amine content (mol%) Curing catalyst (PHR weight %) PMDA BPDA PDA MDA/ODA PBI Embodiment 1 40 60 70 20 10 30 Embodiment 2 40 60 70 20 10 20 Embodiment 3 40 60 70 20 10 15 Embodiment 4 40 60 70 20 10 8 Embodiment 5 20 80 70 20 10 15 Embodiment 6 70 30 70 20 10 15 Comparison Example 1 100 0 90 10 0 0 Comparison Example 2 0 100 90 10 0 0 Comparison Example 3 40 60 90 10 0 0 Comparison Example 4 40 60 90 10 0 50 * PHR: Parts added per 100 parts of resin or rubber

＜ Experimental example ＞ Physical property measurement of polyimide film

In the flexible metal foil laminates manufactured in Examples 1 to 6 and Comparative Examples 1 and 2, the metal was etched using the second ferric chloride solution and then washed with distilled water to separate the polyimide film. The physical properties of the separated polyimide film were measured by the following method.

1 ） Tensile strength

Using UTM (INSTRON-3345), the polyimide film was cut into pieces with a width of 10 mm and a length of 100 mm (effective measurement range of 50 mm), and then measured at a speed of 50.8 mm/min.

2 ) Resistance

Using a loop stiffness tester (TOYOSEKI-DA), a 12.5 micron thick polyimide film was cut into 15 mm wide and 100 mm long pieces and fixed on the measuring table. At this time, the actual measured length of the sample was 50 mm, and the width when formed into a loop was 20 mm. The force detector was measured at 13 mm.

3 ) Thermal expansion coefficient ( CTE ）

A 20 μm thick polyimide film was cut into pieces with a width of 4 mm and a length of 50 mm using TMA (HITACHI-7100). A tension of 30 mN was applied and the thermal expansion coefficient was measured in the range of 100 ℃ to 250 ℃.

4 ） MIT Folding resistance

The measurement is performed using MIT-DA (TOYOSEKI) according to the JIS 6471 method. After attaching the cover layer (PI - 12.5 microns, adhesive - 15 microns), the measurement is performed using the MIT measuring device, and the number of bends until the pattern breaks is counted after repeated bending at 90° or 135°.

The purpose of attaching the cover sheet during measurement is to replicate the flexible printed circuit board (FPCB) and minimize measurement deviation.

5 ) Dimensional stability

After etching the 290 x 270 mm FCCL, it was dried naturally and then stored at 23°C/50% RH for 2 hours and the position between holes was measured. A hole was punched at the top of the 250 x 230 mm sample center. After heating at 150°C for 30 minutes, it was stored at 23°C/50% RH for 2 hours and the position between holes was measured.

FIG. 3 is used to explain the specific calculation method of the dimensional change rate, and shows the positions of each hole in the sample.

The dimensional change rate (Heating DS) is calculated using the following formula. Dimensional change rate in MD direction (%) = (L _M2 -L _M )/L _M X 100 Dimensional change rate in TD direction (%) = (L _T2 -L _T )/L _T X 100 L _M = (A, B hole distance + C, D hole distance)/2 L _T = (A, C hole distance + B, D hole distance)/2 L _M : Hole distance in MD direction of circular plate L _M1 : Hole distance in MD direction after etching L _M2 : Hole distance in MD direction after heating L _T : Hole distance in TD direction of circular plate L _T1 : Hole distance in TD direction after etching L _T2 : Hole distance in TD direction after heating The values of the evaluated properties are shown in Table 2.

[Table 2] Young's modulus CTE Resistance MIT folding resistance Dimensional change rate (Heating DS) (GPa) (ppm/K) (N/m) C/L pasting (number of times) MD/TD (%) Embodiment 1 4.9 14.9 1.67 13,000 0.05/0.05 Embodiment 2 4.7 14.8 1.60 15,000 0.06/0.04 Embodiment 3 4.6 13.1 1.47 17,000 0.03/0.00 Embodiment 4 4.7 12.8 1.61 15,900 0.02/0.01 Embodiment 5 4.7 13.9 1.60 16,100 0.04/0.05 Embodiment 6 4.7 12.3 1.59 16,000 0.03/0.02 Comparison Example 1 6.0 9.5 1.83 10,000 0.00/-0.01 Comparison Example 2 4.2 25.7 1.32 18,200 0.13/0.15 Comparison Example 3 5.8 16.5 2.14 8,200 0.12/0.10 Comparison Example 4 6.0 17.9 2.19 7,500 0.15/0.15

Referring to Table 2, the polyimide film of the embodiment is superior to the polyimide film of the comparative example in terms of MIT folding endurance, dimensional stability, and heat resistance, and has low repellency.

Specifically, after the cover layer is attached to the polyimide film of the embodiment, the number of bends in the MIT folding endurance evaluation is more than 13,000 times, showing excellent bending resistance.

In addition, the Young's modulus is about 4.5 GPa to 5 GPa, and the coefficient of linear thermal expansion (CTE) measured in the range of 100 ℃ to 250 ℃ is about 12 ppm/K to 15 ppm/K.

According to the resistance test results, the stiffness of the polyimide film of the embodiment is less than 1.7 N/m, which is lower than that of the polyimide film of the comparative example.

That is, the polyimide film of the embodiment has low stiffness and thus low resistance, which indicates that it has low modulus characteristics.

In summary, the embodiments are described through limited drawings, and a person skilled in the art can make various changes and modifications based on the description. For example, the described technology is performed in a different order from the described method, and/or the described components are combined or combined in a different form from the described method, or replaced or substituted by other components or equivalents, and appropriate results can also be obtained.

Therefore, other embodiments, other implementations, and equivalents of the patent applications are within the scope of the appended patent applications.

10: Display 11: Flexible printed circuit board 12: Anisotropic conductive film 13: Terminal area 14: Heat dissipation plate 15: Thermal conductive tape 100: Metal foil 200: Polyimide film

FIG. 1 shows a form of reducing the display frame by folding the FPCB at the edge of the display panel backward. FIG. 2 shows a cross-sectional view of a flexible metal foil laminate according to one embodiment of the present invention. FIG. 3 shows the positions of the holes of the display sample, thereby illustrating the specific calculation method of the dimensional variation rate.

100:Metal foil

200: Polyimide film

Claims (13)

A composition for manufacturing a polyimide film, comprising: an aromatic dianhydride; a diamine; and a curing catalyst, wherein the curing catalyst comprises at least one selected from the group consisting of imidazole compounds, quinolinone compounds, and quinoline compounds, wherein the diamine comprises: a first diamine, comprising p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), or both of the above; a second diamine, comprising 4,4'-diaminodiphenyl ether (ODA), 4,4'-diaminodiphenylmethane (MDA), or both of the above; and a third diamine, comprising 2-(4-aminophenyl)-5-aminobenzimidazole (P-PDA). BI); and wherein, relative to 100 parts by weight of the total content of the aromatic dianhydride and the diamine, the curing catalyst is 5 parts by weight to 40 parts by weight, wherein, relative to the total content of the diamine, the third diamine included is 1 mol% to 30 mol%, wherein, the polyimide film used for the flexible metal foil laminate has a dimensional change rate of less than 0.1% after heat treatment at a temperature of 150°C for 30 minutes, and the dimensional change rate is calculated by the following formula 1: [Formula 1] Dimensional change rate (%) = {(average pore distance after heat treatment - average pore distance before heat treatment) / average pore distance before heat treatment} x 100. A composition for manufacturing a polyimide film as described in claim 1, wherein the aromatic dianhydride includes one or more selected from the group consisting of pyromellitic dianhydride (PMDA), biphenyltetracarboxylic dianhydride (BPDA), bisphenol A dianhydride (BPADA), and 4,4'-(hexafluoroisopropylene) diphthalic anhydride (6FDA). A composition for manufacturing a polyimide film as described in claim 1, wherein the diamine is 10 to 200 parts by weight relative to 100 parts by weight of the aromatic dianhydride. The composition for manufacturing a polyimide film as described in claim 1, wherein the imidazole compound includes one or more selected from the group consisting of imidazole, benzimidazole, 1-methylimidazole, 1-(trimethylsilyl)-imidazole, 1,2-dimethylimidazole, 1-(3-aminopropyl)-imidazole, 2-alkylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, and 3-phenylimidazole. The composition for manufacturing a polyimide film as described in claim 1, wherein the quinolinone compound includes one or more selected from the group consisting of quinolinone, 1,2-dihydro-2,2,4-trimethylquinolinone, 2-chloro-3-(chloromethyl)quinolinone, 4-(4-dimethylaminostyryl)quinolinone, and 6-(aminomethyl)quinolinone. The composition for manufacturing a polyimide film as described in claim 1, wherein the quinoline compound includes one or more selected from the group consisting of quinoline, isoquinoline, and benzoquinoline. A composition for manufacturing a polyimide film as described in claim 1, wherein the solid content is 5% to 20% by weight and the viscosity is 10,000 centipoise (cP) to 30,000 centipoise. A method for preparing a composition for manufacturing a polyimide film comprises the following steps: dissolving a diamine in an organic solvent to prepare a diamine solution; and adding an aromatic dianhydride and a curing catalyst to the diamine solution, wherein the curing catalyst comprises one or more selected from the group consisting of imidazole compounds, quinolinone compounds, and quinoline compounds, wherein the diamine comprises: a first diamine, which comprises p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), or both of the above; a second diamine, which comprises 4,4'-diaminodiphenyl ether (ODA), 4,4'-diaminodiphenylmethane (MDA), or both of the above; and a third diamine, which comprises 2-(4 -aminophenyl)-5-aminobenzimidazole (PBI); and wherein, relative to 100 parts by weight of the total content of the aromatic dianhydride and the diamine, the curing catalyst is 5 parts by weight to 40 parts by weight, wherein, relative to the total content of the diamine, the third diamine included is 1 mol% to 30 mol%, wherein, the polyimide film used for the flexible metal foil laminate has a dimensional change rate of less than 0.1% after heat treatment at a temperature of 150°C for 30 minutes, and the dimensional change rate is calculated by the following formula 1: [Formula 1] Dimensional change rate (%) = {(average pore distance after heat treatment - average pore distance before heat treatment) / average pore distance before heat treatment} x 100. A polyimide film for a flexible metal foil laminate is prepared from a composition for producing a polyimide film including an aromatic dianhydride, a diamine, and a curing catalyst, and has a Young's modulus of less than 5 GPa and a coefficient of thermal expansion (CTE) of less than 15 ppm/K. The curing catalyst includes at least one selected from the group consisting of imidazole compounds, quinolinone compounds, and quinoline compounds, and the diamine includes: a first diamine including p-phenylenediamine (p-PDA), m-phenylenediamine (m-PDA), or both of the above; a second diamine including 4,4'-diaminodiphenyl ether (ODA), 4,4'-diaminodiphenylmethane (MDA), or both of the above; and a third diamine including 2-(4-aminophenyl)-5-aminobenzimidazole (PBI); and wherein, relative to 100 parts by weight of the total content of the aromatic dianhydride and the diamine, the curing catalyst is 5 parts by weight to 40 parts by weight, wherein, relative to the total content of the diamine, the third diamine included is 1 mol% to 30 mol%, wherein, the polyimide film used for the flexible metal foil laminate has a dimensional change rate of less than 0.1% measured after heat treatment at a temperature of 150°C for 30 minutes, and the dimensional change rate is calculated by the following formula 1: [Formula 1] Dimensional change rate (%) = {(average pore distance after heat treatment - average pore distance before heat treatment) / average pore distance before heat treatment} x 100. The polyimide film for a flexible metal foil laminate as described in claim 9, wherein the polyimide film for a flexible metal foil laminate is bent more than 10,000 times in the MIT folding endurance test using the JIS C 6471 method when the cover layer is attached. A polyimide film for a flexible metal foil laminate as described in claim 9, wherein the rigidity is 1.0 N/m to 1.7 N/m. A flexible metal foil laminate, comprising: a metal foil; and a polyimide film laminated on one or both sides of the metal foil, wherein the polyimide film is the polyimide film as described in claim 9. A flexible metal foil laminate as described in claim 12, wherein the metal foil includes one or more selected from the group consisting of rolled copper foil, electrolytic copper foil, aluminum foil, and nickel foil.