TWI877695B - Polyimide film, manufacturing method of the same, flexible metal foil laminate and electronic components including the same - Google Patents

Abstract

The present invention provides a polyimide film having a surface hardness of 0.4 GPa or more and 0.6 GPa or less measured by a nanoindenter and a method for manufacturing the same.

Description

Polyimide film, method for producing the same, flexible metal foil laminate containing the same, and electronic component containing the same

The present invention relates to a polyimide film having excellent dimensional stability and adhesion, and more specifically, to a polyimide film having high surface hardness, minimizing the difference between room temperature adhesion and heat-resistant adhesion, and a method for manufacturing the same.

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

Polyimide films have attracted much attention as materials for various electronic devices requiring the above-mentioned properties.

Microelectronic components using polyimide films can be, for example, circuits integrated into highly flexible ultra-thin circuit substrates to cope with the trend toward lightweight and miniaturization of electronic products. Polyimide films are particularly widely used as insulating films for ultra-thin circuit substrates.

The structure of the aforementioned ultra-thin circuit substrate is generally that a circuit including a metal foil is formed on an insulating film. In a broad sense, such an ultra-thin circuit substrate is called a flexible metal foil clad laminate (Flexible Metal Foil Clad Laminate). When a thin copper plate is used as the metal foil, in a narrow sense, it is also called a flexible copper clad laminate (Flexible Copper Clad Laminate: FCCL).

As a method for manufacturing a flexible metal-clad laminate, for example: (i) a casting method in which polyamide as a precursor of 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 by sputtering; and (iii) a lamination method in which a polyimide film and a metal foil are bonded by heat and pressure using thermoplastic polyimide.

In particular, the metallization method, for example, sputtering a metal such as copper on a polyimide film with a thickness of 20 μm to 38 μm and depositing a tie layer and a seed layer in sequence to produce a flexible metal-clad laminate, has advantages in forming ultra-fine circuits with a pitch of less than 35 μm in the circuit pattern, and is widely used to manufacture flexible metal-clad laminates for COF (chip on film).

The polyimide film used in the flexible metal-clad laminate by the metallization method needs to have high dimensional stability and good adhesion to the sputtered metal foil. However, the polyimide film with high dimensional stability usually has the problem of poor adhesion to the sputtered metal foil.

Therefore, there is an urgent need for a polyimide film having both dimensional stability and excellent adhesion to sputtered metal foil.

In particular, it is necessary to minimize the reduction in adhesion to the sputtered metal foil caused by dimensional changes of the polyimide film during the sputtering process and subsequent processes.

The matters described in the above background technology are used to help understanding the background of the invention and may include matters of the prior art that are not known to ordinary technicians in this technical field.

[Prior art document] [Patent document] Patent document 1: Korean Patent Publication No. 10-2020-0120515.

[Technical topics]

Therefore, an object of the present invention is to provide a polyimide film having both high dimensional stability and excellent adhesion.

In particular, the object is to provide a polyimide film having excellent surface hardness and minimizing the reduction in adhesion with a sputtered metal foil during a sputtering process and subsequent processes.

However, the issues to be solved by the present invention are not limited to the issues mentioned above, and other issues not mentioned can be clearly understood by practitioners from the following description. [Technical Solution]

To achieve the above-mentioned purpose, one aspect of the present invention provides a polyimide film, wherein:

The surface hardness measured by a nanoindenter is between 0.4 GPa and 0.6 GPa.

Another aspect of the present invention provides a method for producing a polyimide film, comprising: (a) a step of polymerizing a dianhydride component and a diamine component in an organic solvent to produce polyamide, wherein the dianhydride component comprises biphenyltetracarboxylic dianhydride (BDPA) and pyromellitic dianhydride (PMDA), and the diamine component comprises two or more selected from the group consisting of p-phenylenediamine (PPD), diaminodiphenyl ether (ODA) and 1,3-bis(aminophenoxy)benzene (TPE-R); and (b) a step of subjecting the polyamide to imidization.

Another aspect of the present invention provides a flexible metal foil laminate comprising the aforementioned polyimide film and a conductive metal foil.

Another aspect of the present invention provides an electronic component including the aforementioned flexible metal-clad foil laminate. [Effect of the invention]

The present invention provides a polyimide film having excellent dimensional stability and adhesion by providing a polyimide film in which the ratio and reaction ratio of dianhydride and diamine components are adjusted.

This polyimide film can be applied to various fields of polyimide films requiring excellent dimensional stability and adhesion, for example, it can be applied to a flexible metal-clad laminated plate manufactured according to a metallization method or an electronic component including such a flexible metal-clad laminated plate.

The terms or words used in this specification and the scope of the patent application shall not be interpreted in a limited manner as the ordinary meaning or the dictionary meaning, but shall be based on the principle that "the inventor can appropriately define the concept of the term in order to describe his own invention in the best way" and shall only be interpreted as the meaning and concept that conforms to the technical idea of the present invention.

Therefore, the configuration of the embodiment described in this specification is only one of the best embodiments of the present invention, and does not all represent the technical ideas of the present invention. Therefore, it should be understood that there will be various equivalents and modifications that can be substituted at the time of this application.

Unless the context clearly indicates otherwise, singular expressions in this specification include plural expressions. In this specification, terms such as "including", "having" or "having" are intended to specify the existence of features, numbers, steps, constituent elements or combinations thereof of the implementation, and should be understood as not excluding the existence or additional possibility of one or more other features or numbers, steps, constituent elements or combinations thereof in advance.

In this specification, "dianhydride" is meant to include precursors or derivatives thereof which may not technically be dianhydrides but nevertheless react with diamines to form polyamides which can in turn be converted into polyimines.

In this specification, "diamine" is meant to include precursors or derivatives thereof which are not technically diamines but nevertheless react with dianhydrides to form polyamides which can in turn be converted into polyimines.

In this specification, when an amount, concentration or other value or parameter is given by listing a range, a preferred range or a preferred upper limit and a preferred lower limit, it should be understood that all ranges formed by any pair of any range upper limit or preferred value and any range lower limit or preferred value are specifically disclosed, regardless of whether the range is disclosed separately.

When a range of numerical values is mentioned in this specification, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within the range, which means that the scope of the present invention is not limited to the specific values mentioned when defining the range.

In this specification, "a to b" and "a~b" in the range of numerical values are defined as ≥a and ≤b.

The surface hardness of the polyimide film of an embodiment of the present invention measured by a nanoindenter may be greater than 0.4 GPa and less than 0.6 GPa.

For example, the surface hardness may be greater than or equal to 0.45 GPa, greater than or equal to 0.5 GPa, or greater than or equal to 0.55 GPa.

If the surface hardness exceeds the above range, metal foil will be difficult to deposit and the room temperature adhesion of the polyimide film will be weakened. If the surface hardness is below the above range, the thermal stability and heat-resistant adhesion of the polyimide film will be reduced.

In one implementation example, the room temperature adhesion between the polyimide film and the metal foil can be greater than 0.6 kgf/cm and less than 0.9 kgf/cm, and the heat-resistant adhesion between the polyimide film and the metal foil can be greater than 0.3 kgf/cm and less than 0.5 kgf/cm.

The room temperature adhesion may be the adhesion between the polyimide film and the metal foil measured at room temperature (15-25° C.) after a metal foil (eg, copper foil) is deposited on the polyimide film by a sputtering process.

In addition, the heat-resistant adhesion may be the adhesion between the polyimide film and the metal foil measured after depositing the metal foil (e.g., copper foil) on the polyimide film by a sputtering process and placing the metal foil at a high temperature (100-200° C.) for a long time (100-300 hours).

For example, the room temperature adhesive force may be greater than or equal to 0.6 kgf/cm and less than or equal to 0.83 kgf/cm, and the heat-resistant adhesive force may be greater than or equal to 0.45 kgf/cm and less than or equal to 0.50 kgf/cm.

If the temperature exceeds or falls below the above-mentioned room temperature and/or heat-resistant adhesion range, problems may occur in the production process of the product to which the polyimide film is applied.

In an implementation example, the adhesion reduction rate expressed by the following mathematical formula 1 may be less than 50%, and the thermal expansion coefficient may be greater than 1 ppm/°C and less than or equal to 15 ppm/°C.

[Mathematical formula 1] Adhesion reduction rate (%) = [(normal temperature adhesion to metal foil - heat-resistant adhesion to metal foil) / normal temperature adhesion to metal foil] * 100

The aforementioned adhesion reduction rate may be, for example, 45% or less, 40% or less, 35% or less, 30% or less, 25% or less, or 20% or less.

On the other hand, the thermal expansion coefficient may be, for example, 4.5 ppm/°C or more and 10 ppm/°C or less.

If the thermal expansion coefficient exceeds the above range, the heat resistance stability of the deposited metal foil and polyimide film will be reduced. If it is below the above range, the room temperature adhesion between the polyimide film and the metal foil will be reduced.

In one implementation example, the polyimide film of the present application can be obtained by subjecting a polyimide solution containing a dianhydride component and a diamine component to an imidization reaction, wherein the dianhydride component includes biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride, BPDA) and pyromellitic dianhydride (PMDA), and the diamine component includes two or more selected from the group consisting of p-phenylenediamine (PPD), diaminodiphenyl ether (ODA) and 1,3-bis(aminophenoxy)benzene (TPE-R).

However, the dianhydride component of the polyimide film of the present application may not include 3,3',4,4'-Benzophenone tetracarboxylic dianhydride (BTDA) and 4,4'-oxydiphthalic anhydride (ODPA).

In addition, the diamine component of the polyimide film of the present application may not contain m-tolidine (MTD).

For example, the diamine component of the polyimide film may be a combination of p-phenylenediamine and diaminodiphenyl ether, or a combination of p-phenylenediamine and 1,3-bis(aminophenoxy)benzene (TPE-R).

The polyimide chain derived from biphenyltetracarboxylic dianhydride has a structure named charge transfer complex (CTC), that is, a regular linear structure in which electron donors and electron acceptors are arranged close to each other, which strengthens the intermolecular interaction.

In addition, pyromellitic dianhydride is a dianhydride component with a relatively rigid structure and can impart appropriate elasticity to the polyimide film, so it is preferred.

On the other hand, biphenyltetracarboxylic dianhydride contains two benzene rings corresponding to the aromatic moiety, whereas pyromellitic dianhydride contains one benzene ring corresponding to the aromatic moiety.

In the dianhydride component, the increase in the content of pyromellitic dianhydride can be understood as an increase in the imide groups in the molecule when the molecular weight is the same. This can be understood as the ratio of the imide groups derived from the aforementioned pyromellitic dianhydride to the imide groups derived from biphenyltetracarboxylic dianhydride in the polyimide polymer chain is relatively increased.

In one implementation example, based on the total content of the aforementioned dianhydride components being 100 mol %, the content of the aforementioned biphenyltetracarboxylic dianhydride may be greater than 40 mol % and less than 99 mol %, the content of the aforementioned pyromellitic dianhydride may be greater than 1 mol % and less than 60 mol %, based on the total content of the aforementioned diamine components being 100 mol %, the content of the aforementioned p-phenylenediamine may be greater than 40 mol % and less than 95 mol %, the content of the aforementioned diaminodiphenyl ether may be less than 30 mol %, and the content of the aforementioned 1,3-bis(aminophenoxy)benzene may be less than 60 mol %.

For example, based on 100 mol % of the total content of the dianhydride components, the content of the biphenyltetracarboxylic dianhydride may be greater than 50 mol % and less than 97 mol %, and the content of the pyromellitic dianhydride may be greater than 3 mol % and less than 50 mol %.

In addition, based on the total content of the aforementioned diamine components as 100 mol %, the content of the aforementioned p-phenylenediamine may be greater than 55 mol % and less than 87 mol %, the content of the aforementioned diaminodiphenyl ether may be less than 13 mol %, and the content of the aforementioned 1,3-bis(aminophenoxy)benzene may be less than 45 mol %.

In the above-mentioned dianhydride component and diamine component, if the content of the short structure monomer such as the above-mentioned p-phenylenediamine and the above-mentioned pyromellitic dianhydride increases, there will be a tendency that the surface hardness of the above-mentioned polyimide film increases and the thermal expansion coefficient decreases.

On the other hand, if the content of the monomer having a soft structure such as diaminodiphenyl ether and biphenyltetracarboxylic acid dianhydride increases in the dianhydride component and the diamine component, the surface hardness of the polyimide film tends to decrease and the thermal expansion coefficient tends to increase.

In the present invention, the production of polyamine acid can be carried out by the following methods, for example: (1) A method of adding the entire amount of the diamine component to a solvent, and then adding the dianhydride component so that the diamine component and the dianhydride component are substantially equimolar and polymerizing; (2) A method of adding the entire amount of the dianhydride component to a solvent, and then adding the diamine component so that the diamine component and the dianhydride component are substantially equimolar and polymerizing; (3) A method of adding a portion of the diamine component to a solvent, mixing a portion of the dianhydride component at a ratio of about 95 to 105 mol% relative to the reaction component, adding the remaining diamine component, and then adding the remaining dianhydride component so that the diamine component and the dianhydride component are substantially equimolar and polymerizing; (4) The method comprises adding the dianhydride component to the solvent, mixing a portion of the diamine compound at a ratio of 95 to 105 mole percent relative to the reaction component, adding the other dianhydride component, and then adding the remaining diamine component, so that the diamine component and the dianhydride component are substantially equal in mole and polymerizing; (5) The method comprises reacting a part of the diamine component with a part of the dianhydride component in a solvent to make one of them excessive to form a first composition, reacting a part of the diamine component with a part of the dianhydride component in another solvent to make one of them excessive to form a second composition, and then mixing the first and second compositions to complete polymerization. At this time, when forming the first composition, if the diamine component is excessive, the dianhydride component is excessive in the second composition, and when the dianhydride component is excessive in the first composition, the diamine component is excessive in the second composition, and the first and second compositions are mixed so that the total diamine component and dianhydride component used in their reaction are substantially equal in mole and then polymerized.

However, the polymerization method is not limited to the above examples, and the polyamine can be produced by any known method.

In a specific example, the method for producing a polyimide film of the present invention may include: (a) a step of polymerizing a dianhydride component and a diamine component in an organic solvent to produce polyamide, wherein the dianhydride component includes biphenyltetracarboxylic dianhydride and pyromellitic dianhydride, and the diamine component includes two or more selected from the group consisting of p-phenylenediamine (PPD), diaminodiphenyl ether (ODA) and 1,3-bis(aminophenoxy)benzene (TPE-R); and (b) a step of subjecting the polyamide to imidization.

In one implementation example, based on the total content of the aforementioned dianhydride components being 100 mol %, the content of the aforementioned biphenyltetracarboxylic dianhydride may be greater than 40 mol % and less than 99 mol %, the content of the aforementioned pyromellitic dianhydride may be greater than 1 mol % and less than 60 mol %, based on the total content of the aforementioned diamine components being 100 mol %, the content of the aforementioned p-phenylenediamine may be greater than 40 mol % and less than 95 mol %, the content of the aforementioned diaminodiphenyl ether may be less than 30 mol %, and the content of the aforementioned 1,3-bis(aminophenoxy)benzene may be less than 60 mol %.

On the other hand, the surface hardness of the polyimide film measured by a nanoindenter can be greater than 0.4 GPa and less than 0.6 GPa, the room temperature adhesion to the metal foil can be greater than 0.6 kgf/cm and less than 0.9 kgf/cm, and the heat-resistant adhesion to the metal foil can be greater than 0.3 kgf/cm and less than 0.5 kgf/cm.

In the present invention, the polymerization method of polyamide as described above can be defined as a random polymerization method, and the polyimide film made of polyamide produced by the process as described above can be preferably applied due to the effects of the present invention of improving mechanical properties, heat resistance and chemical resistance.

On the other hand, the solvent used for synthesizing polyamide is not particularly limited, and any solvent can be used as long as it can dissolve polyamide, but an amide solvent is preferred.

Specifically, the aforementioned solvent may be an organic polar solvent, and more specifically, may be an aprotic polar solvent, for example, may be one or more selected from the group consisting of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), p-chlorophenol, o-chlorophenol, γ-butyrolactone (GBL), and diglyme (Diglyme), but is not limited thereto and may be used alone or in combination of two or more as needed.

In one example, the aforementioned solvent may preferably include N,N-dimethylformamide and N,N-dimethylacetamide.

In addition, fillers other than nanosilicon dioxide can be added during the polyamide manufacturing process to improve various properties of the film, such as slip, thermal conductivity, corona resistance, and ring hardness. The added filler material is not particularly limited, and as a preferred example, it can be titanium oxide, aluminum oxide, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, etc.

The particle size of the filler is not particularly limited and can be determined according to the membrane properties to be modified and the type of filler added. Generally speaking, the average particle size is 0.05 μm to 100 μm, preferably 0.1 μm to 75 μm, more preferably 0.1 μm to 50 μm, and particularly preferably 0.1 μm to 25 μm.

If the particle size is below this range, the modification effect is difficult to show, and if it exceeds this range, the surface properties may be greatly damaged or the mechanical properties may be greatly reduced.

In addition, the amount of filler added is not particularly limited and can be determined according to the membrane properties to be modified or the filler particle size, etc. Generally speaking, the amount of filler 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 polyimide.

If the amount of filler added is below this range, the modifying effect of the filler is difficult to be exhibited, and if it exceeds this range, there is a possibility that the mechanical properties of the film will be greatly damaged. The method of adding the filler is not particularly limited, and any known method can be used.

In the manufacturing method of the present invention, the polyimide film can be manufactured according to a thermal imidization method and a chemical imidization method.

Alternatively, it can be produced by a combined imidization method using a thermal imidization method and a chemical imidization method.

The so-called thermal imidization method is a method that uses a heat source such as hot air or an infrared dryer to induce the imidization reaction without using a chemical catalyst.

The aforementioned thermal imidization method can heat-treat the aforementioned gel film at a variable temperature in the range of 100 to 600°C to imidize the amide groups present in the gel film. Specifically, the heat treatment can be performed at 200 to 500°C, and more specifically, at 300 to 500°C to imidize the amide groups present in the gel film.

However, during the process of forming the gel film, a portion of the polyamine (about 0.1 mol% to 10 mol%) will be imidized. For this purpose, the polyamine composition can be dried at a variable temperature in the range of 50°C to 200°C, which can also be included in the scope of the aforementioned thermal imidization method.

As for the chemical imidization method, a polyimide membrane can be manufactured using a dehydrating agent and an imidizing agent according to a method known in the industry. The so-called "dehydrating agent" refers to a substance that promotes the ring-closing reaction by dehydrating the polyamide. As non-limiting examples thereof, aliphatic anhydrides, aromatic anhydrides, N, N'-dialkylcarbodiimide, halogenated lower aliphatic, halogenated lower fatty acid anhydrides, aromatic phosphine dihalides and sulfinyl halides can be used. Among them, from the perspective of availability and cost, aliphatic anhydrides are preferred. As non-limiting examples thereof, acetic anhydride (or anhydrous acetic acid, AA), propionic anhydride and lactic anhydride can be used, and they can be used alone or in combination of two or more.

In addition, the term "imidizing agent" means a substance having an effect of promoting the ring-closing reaction of polyamide, and may be, for example, an imine component such as an aliphatic tertiary amine, an aromatic tertiary amine, and a heterocyclic tertiary amine. Among them, from the perspective of reactivity as a catalyst, a heterocyclic tertiary amine may be preferred. Non-limiting examples of heterocyclic tertiary amines include quinoline, isoquinoline, β-methylpyridine (BP), pyridine, etc., which may be used alone or in combination of two or more.

The amount of the dehydrating agent added is preferably within the range of 0.5 to 5 mol, and more preferably within the range of 1.0 to 4 mol, relative to 1 mol of the amide group in the polyamide. In addition, the amount of the imidizing agent added is preferably within the range of 0.05 to 2 mol, and more preferably within the range of 0.2 to 1 mol, relative to 1 mol of the amide group in the polyamide.

If the amount of the dehydrating agent and the imidizing agent exceeds the above range, the chemical imidization is insufficient, cracks are formed on the manufactured polyimide film, and the mechanical strength of the film is reduced. In addition, if the amount of these additions exceeds the above range, the imidization will proceed too quickly, and at this time, it will be difficult to cast into a film form or the manufactured polyimide film will show brittle characteristics, so it is not recommended.

As an example of the composite imidization method, a dehydrating agent and an imidizing agent may be added to a polyamide solution, and then heated at 80 to 200°C, preferably 100 to 180°C. After partial curing and drying, the solution may be heated at 200 to 400°C for 5 to 400 seconds to produce a polyimide film.

The present invention provides a flexible metal-clad laminate comprising the polyimide film and a conductive metal foil.

The metal foil used is not particularly limited, but for example, when the multilayer film of the present invention is used for electronic equipment or electrical equipment, it can be a metal foil including copper or copper alloy, stainless steel or its alloy, nickel or nickel alloy (including 42 alloy), aluminum or aluminum alloy.

In common flexible metal foil-clad laminated plates, copper foils called rolled copper foils and electrolytic copper foils are often used, which can also be preferably used in the present invention. In addition, the surfaces of these metal foils can also be coated with a rust-proof layer, a heat-resistant layer or an adhesive layer.

In the present invention, the thickness of the metal foil is not particularly limited as long as it is a thickness that can fully exert its function according to its application.

The flexible metal foil laminated plate of the present invention may be a structure in which a metal foil is laminated on one side of the polyimide film or an adhesive layer containing thermoplastic polyimide is attached to one side of the polyimide film, and the lamination is performed in a state in which the metal foil is attached to the adhesive layer.

The present invention also provides an electronic component comprising the above-mentioned flexible metal-clad foil laminate as an electrical signal transmission circuit.

The following is a more detailed description of the functions and effects of the invention by means of specific embodiments of the invention. However, such embodiments are only provided as examples of the invention, and the scope of the invention is not limited thereby.

Production Example 1: Production of polyimide film.

After nitrogen was injected into a 500 ml reactor equipped with a stirrer and a nitrogen injection/exhaust tube, DMF was added, and the reactor temperature was set to 30°C. As the diamine component, part of p-phenylenediamine (PPD), m-tolidine (MTD), 1,3-bis(aminophenoxy)benzene (TPE-R) and diaminodiphenyl ether (ODA) was selected and added, and as the dianhydride component, part of biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA) and oxydiphthalic anhydride (ODPA) was selected and added, and it was confirmed that they were completely dissolved.

Then, under a nitrogen atmosphere, the reactor temperature was heated to 40°C and stirred for 120 minutes to produce a polyamine solution.

To the polyimide solution thus prepared, 3 mol of acetic anhydride and 1 mol of isoquinoline were added based on 1 mol of the amide group to obtain a precursor composition for a polyimide membrane.

The above-mentioned precursor composition for polyimide film was cast on a SUS plate using a doctor blade and dried at 110° C. for 4 minutes to prepare a gel film.

After the gel film was separated from the SUS plate, it was heat-treated at 380°C for 8 minutes to produce a polyimide film having a thickness of 35 μm.

The thickness of the manufactured polyimide film was measured using an electric film thickness tester manufactured by Anritsu.

<Examples 1 to 3 and Comparative Examples 1 to 4>

The production was carried out according to the production example described above, and the contents of the diamine monomer and the dianhydride monomer were adjusted as shown in Table 1 below.

[Table 1] Dianhydride (mol%) Diamine (mol%) PMDA BPDA ODPA ODA TPE-R MTD PPD Embodiment 1 25 75 - - 45 - 55 Embodiment 2 3 97 - - 45 - 55 Embodiment 3 50 50 - 13 - - 87 Comparison Example 1 50 50 - - - 40 60 Comparison Example 2 50 50 - 100 - - - Comparison Example 3 25 75 - 55 45 - - Comparison Example 4 25 50 25 55 45 - -

Manufacturing Example 2: Manufacturing of Flexible Metal Foil Laminated Plates.

A copper thin film layer with a thickness of about 80 to 300 nm was deposited on the polyimide film of Examples 1 to 3 and Comparative Examples 1 to 4 manufactured in Manufacturing Example 1 by sputtering as a copper seed layer for electroplating electrodes, and a copper conductive layer with a thickness of about 8 to 9 μm was formed by electroplating.

(1) Thermal expansion coefficient measurement

The coefficient of thermal expansion (CTE) was measured using a TA company thermomechanical analyzer Q400. The polyimide films of Examples 1 to 3 and Comparative Examples 1 to 4 manufactured in Manufacturing Example 1 were cut into pieces with a width of 4 mm and a length of 20 mm. A tension of 0.05 N was applied in a nitrogen atmosphere, and the temperature was raised from 30°C to 400°C at a rate of 10°C/min and then cooled again at a rate of 10°C/min. At the same time, the slope in the range of 50°C to 200°C (the dimensional change rate caused by the temperature change in the range of 50°C to 200°C (ppm/°C)) was measured.

(2) Surface hardness measurement

The polyimide films of Examples 1 to 3 and Comparative Examples 1 to 4 manufactured in Manufacturing Example 1 were cut into pieces with a width of 100 mm and a length of 100 mm, and then the surface hardness was measured using an iNano nanoindenter manufactured by KLA-Tenco. The nanoindenter can measure the surface hardness by measuring the force applied to the probe when the probe is pressed into the sample.

(3) Room temperature adhesion measurement

A wet etching process was applied to the flexible metal plate laminated plate manufactured according to Manufacturing Example 2 using the polyimide films of Examples 1 to 3 and Comparative Examples 1 to 4. After being etched into a rod shape with a width of 2 mm, the room temperature adhesion was measured using a Universal Testing Machine by performing a 90° peel test at a speed of 20 mm/min.

The wet etching process is performed in the following order: a rod-shaped coating having a width of 2 mm is attached to the flexible metal foil layer press plate, an etching liquid (ferric chloride [FeCl3 III]) is sprayed to etch the metal to form a rod-shaped pattern, and then the coating is removed.

(4) Heat-resistant adhesion measurement

A wet etching process was applied to the flexible metal plate laminated plate manufactured according to Manufacturing Example 2 using the polyimide films of Examples 1 to 3 and Comparative Examples 1 to 4, and after being etched into a rod shape with a width of 2 mm, heat treatment was performed at 150°C for 168 hours.

The wet etching process was performed in the same manner as the room temperature adhesion measurement.

Then, the heat-resistant adhesion was measured by a 90° peel test at a speed of 20 mm/min using a Universal Testing Machine.

The coefficient of thermal expansion (CTE), surface hardness, room temperature adhesion, and heat-resistant adhesion of the polyimide films of Examples 1 to 3 and Comparative Examples 1 to 4 manufactured in Manufacturing Example 1 measured by the above-mentioned measurement method are shown in Table 2 below.

In addition, the reduction in adhesion calculated according to the above mathematical formula 1 is shown in the following Table 2.

[Table 2] CTE (ppm/℃) Surface hardness(GPa) Adhesion at room temperature (kgf/cm) Heat resistant adhesion (kgf/cm) Adhesion force reduction (%) Embodiment 1 10.0 0.48 0.60 0.50 17 Embodiment 2 8.6 0.51 0.83 0.45 46 Embodiment 3 4.5 0.55 0.73 0.45 33 Comparison Example 1 1.0 0.69 0.57 0.53 36 Comparison Example 2 33.5 0.33 0.92 0.28 70 Comparison Example 3 34.5 0.39 1.01 0.24 76 Comparison Example 4 37.1 0.38 0.93 0.27 71

The measurement results show that the polyimide films of Examples 1 to 3 exhibit a thermal expansion coefficient greater than 1 ppm/°C and less than or equal to 15 ppm/°C, a surface hardness of greater than 0.4 Gpa and less than 0.6 Gpa, a room temperature adhesion of greater than 0.6 kgf/cm and less than 0.9 kgf/cm, a heat-resistant adhesion of greater than 0.3 kgf/cm and less than 0.5 kgf/cm, and an adhesion reduction characteristic of less than 50%.

In comparison, the polyimide films of Comparative Examples 1 to 4 cannot satisfy the property range of the polyimide films of the present application in terms of any one of the thermal expansion coefficient, surface hardness, room temperature adhesion, heat-resistant adhesion and adhesion reduction properties.

Therefore, it can be confirmed that the multilayer polyimide films of Examples 1 to 3 manufactured within the appropriate range of the present case have excellent thermal dimensional stability, dimensional stability to moisture, and adhesion to copper foil. However, when the temperature exceeds the appropriate range of the present case, it is difficult to fully satisfy the thermal dimensional stability, dimensional stability to moisture, and adhesion to copper foil of the multilayer polyimide films of the present case.

That is, it can be confirmed that the multilayer polyimide film having excellent dimensional stability and adhesion to copper foil and satisfying all the various conditions applicable to the application field is a polyimide film produced within the appropriate range of the present case.

The embodiments of the polyimide film and the method for producing the polyimide film of the present invention are only preferred embodiments that enable ordinary skilled persons in the technical field to which the present invention belongs to easily implement the present invention, and are not limited to the aforementioned embodiments. Therefore, the scope of the patent application of the present invention is not limited thereby. Therefore, the true technical protection scope of the present invention should be determined according to the technical idea of the accompanying patent application scope. In addition, it is self-evident for practitioners that various substitutions, deformations and changes can be realized within the scope of the technical idea of the present invention, and it is self-evident for practitioners that the parts that can be easily changed by practitioners are also included in the scope of the patent application of the present invention.

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without.

Claims (10)

A polyimide film, wherein the polyimide film is obtained by subjecting a polyamide solution containing a dianhydride component and a diamine component to an imidization reaction, wherein the dianhydride component includes biphenyltetracarboxylic dianhydride and pyromellitic dianhydride, and the diamine component includes p-phenylenediamine (PPD) and 1,3-bis(aminophenoxy)benzene (TPE-R), wherein the content of p-phenylenediamine is 40 mol% or more and 95 mol% or less based on the total content of the diamine component of 100 mol%, wherein the room temperature adhesion between the polyimide film and the metal foil is 0.6 kgf/cm or more and 0.9 kgf/cm or less, The room temperature adhesion is measured by sputtering and stretching the polyimide film on which the metal foil is deposited at a speed of 20 mm/min in a 90° peeling test using a universal testing machine. The surface hardness of the polyimide film measured by a nanoindenter is greater than 0.4 GPa and less than 0.6 GPa. The polyimide film as described in claim 1, wherein the heat-resistant adhesion between the polyimide film and the metal foil is greater than or equal to 0.3 kgf/cm and less than or equal to 0.5 kgf/cm. The polyimide film as described in claim 1, wherein the adhesion reduction rate represented by the following mathematical formula 1 is less than 50%, and the thermal expansion coefficient is greater than 1 ppm/℃ and less than or equal to 15 ppm/℃, [Mathematical formula 1] Adhesion reduction rate (%) = [(room temperature adhesion to metal foil - heat-resistant adhesion to metal foil) / room temperature adhesion to metal foil] * 100. The polyimide film as described in claim 1, wherein, based on 100 mol % of the total content of the dianhydride components, the content of the biphenyltetracarboxylic dianhydride is greater than 40 mol % and less than 99 mol %, the content of the pyromellitic dianhydride is greater than 1 mol % and less than 60 mol %, and based on 100 mol % of the total content of the diamine components, the content of the 1,3-bis(aminophenoxy)benzene is less than 60 mol %. A method for producing a polyimide film comprises the following steps: (a) a step of polymerizing a dianhydride component and a diamine component in an organic solvent to produce polyamide, wherein the dianhydride component comprises biphenyltetracarboxylic dianhydride and pyromellitic dianhydride, and the diamine component comprises p-phenylenediamine (PPD) and 1,3-bis(aminophenoxy)benzene (TPE-R); and (b) a step of subjecting the polyamide to imidization, wherein, based on the total content of the diamine component being 100 mol%, the content of the p-phenylenediamine is greater than 40 mol% and less than 95 mol%, wherein the room temperature adhesion of the polyimide film to the metal foil is greater than 0.6 kgf/cm and less than 0.9 kgf/cm, The room temperature adhesion is measured by sputtering and stretching the polyimide film on which the metal foil is deposited at a speed of 20 mm/min in a 90° peeling test using a universal testing machine. The surface hardness of the polyimide film measured by a nanoindenter is greater than 0.4 GPa and less than 0.6 GPa. A method for producing a polyimide film as described in claim 5, wherein, based on 100 mol % of the total content of the dianhydride components, the content of the biphenyltetracarboxylic dianhydride is greater than 40 mol % and less than 99 mol %, the content of the pyromellitic dianhydride is greater than 1 mol % and less than 60 mol %, and based on 100 mol % of the total content of the diamine components, the content of the 1,3-bis(aminophenoxy)benzene is less than 60 mol %. The method for producing a polyimide film as described in claim 5, wherein the heat-resistant adhesion between the polyimide film and the metal foil is greater than or equal to 0.3 kgf/cm and less than or equal to 0.5 kgf/cm. A method for producing a polyimide film as described in claim 5, wherein the adhesion reduction rate represented by the following mathematical formula 1 is less than 50%, and the thermal expansion coefficient is greater than 1 ppm/°C and less than or equal to 15 ppm/°C. [Mathematical formula 1] Adhesion reduction rate (%) = [(room temperature adhesion to metal foil - heat-resistant adhesion to metal foil) / room temperature adhesion to metal foil] * 100. A flexible metal foil laminate comprising a polyimide film as described in any one of claims 1 to 4 and a conductive metal foil. An electronic component comprising the flexible metal foil laminate as described in claim 9.