KR20070092779A - Polyimide film and metal-clad laminates - Google Patents

Abstract

A polyimide film is provided to have excellent characteristics such as dimensional stability, high elasticity, a low coefficient of linear thermal expansion, heat resistance, and flexing resistance and be useful as a base film for flexible wiring boards and copper clad laminates. A polyimide film is formed of polyimide having a molecular weight of 5,000-10,000,000 and comprising 0.25-90.25mol% of a repeat unit represented by the following formula 1, 0.25-90.25mol% of a repeat unit represented by the following formula 2, 0.25-90.25mol% of a repeat unit represented by the following formula 3, and 0.25-90.25mol% of a repeat unit represented by the following formula 4. In the formulae 3 and 4, Ar represents the following formula (a).

Description

Polyimide film and metal-clad laminates

The present invention relates to a polyimide film and a metal laminate, and more particularly, prepared from polyamic acid obtained from two kinds of diamines and two kinds of dianhydrides to provide dimensional stability, high modulus of elasticity, low linear thermal expansion coefficient, and flex resistance. The present invention relates to a polyimide film having excellent properties and useful as a base film such as a flexible wiring board and a copper foil laminate, and a metal laminate including the same.

Polyimide films are known for their excellent properties such as high heat resistance, cold resistance, chemical resistance, electrical insulation ability and mechanical strength, and are widely used in electrical insulation films, thermal insulation films, base films for flexible wiring boards (FPCs), flexible copper foil laminates, etc. It is widely used as a base film.

For example, FPC has a basic structure in which a circuit pattern is formed on a flexible and thin base film and a film called a cabaret film is bonded to the surface of the circuit. Currently, polyimide film is most widely used as a material capable of satisfying the required characteristics such as chemical resistance, heat resistance, and environmental resistance.

 In general, polyimide films are desired to have a low coefficient of linear expansion, a high modulus of elasticity, and a low absorption expansion coefficient. When the polyimide film and the copper foil are joined together and processed, such as a flexible wiring board or a flexible copper foil laminate (FCCL), it is not preferable that the coefficient of linear expansion of the film is significantly different from that of the copper foil. That is, if the linear expansion coefficients of the polyimide film and the copper foil are significantly different, warpage may occur in the bonded product and it may be difficult to process, and as a result, the overall dimensional accuracy and production yield may decrease. Therefore, it is preferable that the polyimide film has a small difference in the coefficient of linear expansion with copper foil.

In order to obtain the polyimide film which has such a characteristic, various attempts are made | formed. First, in order to increase the modulus of elasticity of polyimide film, it is widely known that a monomer having a rigid structure, that is, a monomer having high linearity may be used. By the way, when a large amount of monomer having high linearity is used, the coefficient of linear expansion of the film becomes too low, which is unsuitable for bonding with copper foil.

There is an example in which a monomer having a relatively rigid structure is used so as to realize a relatively high elastic modulus but not lower the coefficient of linear expansion too much. However, when a rigid, high linearity monomer is used, the flexibility of the film is generally impaired, which may cause difficulty in the fact that a folded plate, which is one of advantages such as a flexible wiring board, is possible.

In other words, in order to increase the flexibility of the base film, a film made of a chemically flexible polyimide may be used. However, in general, a flexible wiring board using the polyimide having high flexibility has a large coefficient of linear expansion and thus used as an insulation material. It has the drawback that it is easy to generate warpage or twist. On the contrary, when the polyimide having a small coefficient of linear expansion is selected, the flexibility of the film itself is lost and becomes very fragile, so that the flexibility of the obtained soluble wiring board is also lowered.

On the other hand, for semiconductor package applications and the like, in particular, the absorption rate is requested to be as low as possible in view of the reliability of the semiconductor, and the absorption coefficient is also low in view of the dimensional stability. In order to lower the water absorption rate and the hygroscopic expansion coefficient, it is effective to reduce the amount of imide groups in the molecular structure. For this reason, the monomer of long chain which contains two or more bending machines in the main chain is used in many cases. As a result, however, the elastic modulus and the linear expansion coefficient are excessively increased, and dimensional stability is sacrificed. In extreme cases, thermoplastics are exhibited, for example, having a glass transition temperature (Tg) at a low temperature of 200 ° C. or lower, which makes them unsuitable for use as a base film. When a linear monomer is used, packing of the molecular chain becomes difficult, sufficient toughness cannot be expressed, and in some cases, filming itself becomes difficult.

Thus, as a characteristic of a polyimide film, there are many points to consider besides reducing high elastic modulus, low coefficient of thermal expansion, and water absorption. However, if one of the characteristics is to be satisfied, it is particularly difficult to obtain a polyimide film having a plurality of good characteristics, such as sacrificing other characteristics.

Accordingly, the present inventors have solved the above problems and have excellent properties such as dimensional stability, high elasticity, low coefficient of thermal expansion, heat resistance, flex resistance, and the like to provide a polyimide film useful as a base film such as a flexible wiring board and a copper foil laminate. Its purpose is.

MEANS TO SOLVE THE PROBLEM In view of the above-mentioned request | requirement, this inventor aims at providing the polyimide film which can highly implement | achieve various characteristics balance as a polyimide film of a specific composition.

Moreover, the objective is also providing the metal laminated body like a copper foil laminated board to which such a polyimide film was applied.

Polyimide film of the present invention for achieving the above object is a repeating unit represented by the following formula 1 0.25 ~ 90.25 mol%, the repeating unit represented by the following formula 2 0.25 ~ 90.25 mol%, the repeating unit represented by the following formula It is characterized by consisting of polyimide having a molecular weight of 5,000 to 10,000,000 including 0.25 to 90.25 mol% and 0.25 to 90.25 mol% of repeating units represented by the following formula (4).

Formula 1

Formula 2

Formula 3

로 표시된다.Wherein Ar is

Is displayed.

Formula 4

로 표시된다.Wherein Ar is

Is displayed.

In the polyimide film of the present invention, inorganic particles may be dispersed in order to further improve the flex resistance, and the inorganic particles may be silica or quartz powder, titanium oxide, aluminum oxide, zircon powder having a particle size of 0.1 to 10 μm. It may be one or more selected from organo clay, magnesium oxide, calcium carbonate and zinc oxide.

The polyimide film of the present invention satisfies the property of having a dimensional strain of 1.0% or less after standing for 24 hours at 50 ° C. and 60% RH; Elongation at break is 20% or more, and the difference between the elongation at break in the fixed direction and the elongation at break in the direction perpendicular to the tenter is 30% or less. In addition, the average coefficient of thermal expansion in the range of 100 to 200 ℃ 10 to 30ppm and satisfies the characteristics of the dimensional strain is 0.1% or less and the glass transition temperature of 250 ℃ or more after 1 hour holding at 250 ℃; According to IPC-TM-650, 2.4.3, the characteristic is that it satisfies the characteristic that the bending resistance measured by the bending resistance tester is 100,000 times or more.

Such a polyimide film can be applied to a metal laminate, and is preferably suitable as a base film.

The present invention will be described in more detail as follows.

The present invention is a polyimide film comprising a polyimide linearly and irregularly including a repeating unit represented by Formula 1, a repeating unit represented by Formula 2, a repeating unit represented by Formula 3, and a repeating unit represented by Formula 4. It is about.

The polyimide film according to the present invention starts from the process of preparing a polyamic acid from two diamines and two dianhydrides in the presence of an organic solvent, wherein the two diamines are 4,4'-dia. Minophenyl ether (hereinafter referred to as ODA) and 4-amino-N- (4-aminophenyl) benzamide (hereinafter referred to as DABA). Specifically, ODA may be used as χ mol% in the total diamine content, and DABA may be used as (100-χ) mol% (where χ is 5.0 ≦ χ ≦ 95.0).

Dianhydrides include pyromellitic dianhydrides (PMDA) and 3,4,3 ', 4'-biphenyl tetracarboxylic dianhydrides (3,4,3', 4'-biphenyl tetracarboxylic). dianhydride (hereinafter BPDA) or 3,4,3 ', 4'-benzophenone tetracarboxylic dianhydride (hereinafter referred to as BTDA) is used. Specifically, PMDA is used as ξmole% in the total dianhydride contents and (100-ξ) mol% (wherein ξ is 5.0 ≦ ξ ≦ 95.0) in BPDA or BTDA.

The polymerization of the polyamic acid using two kinds of diamines and two kinds of dianhydrides is carried out according to the conventional polymerization method of polyamic acid, and the reaction ratios and reaction conditions of the diamines and dianhydrides are particularly limited. no.

As a method of manufacturing a polyimide film from such a polyamic acid polymer, the method is generally divided according to the method of performing imidation, The thermal method which dehydrates by heating; There is also a chemical method using a dehydrating agent or an imidization catalyst. Any of these methods may be used, or both chemical and thermal methods may be used in combination. By the way, according to the chemical method which adds a dehydrating agent and a catalyst, and heats and drys, the characteristic which is more efficient and excellent than a thermal method can be provided to a film. Even when a dehydrating agent or an imidization catalyst is not used, the monomers of the present invention can be used to achieve the same characteristics by a drawing process, for example, but a chemical method is preferable in terms of productivity. .

Such dehydrating agents include aliphatic acid anhydrides such as acetic anhydride, aromatic acid anhydrides, and the like. As a catalyst used for imidation, tertiary amines, such as pyridine, (alpha)-picoline, (beta)-picoline, trimethylamine, dimethylaniline, triethylamine, isoquinone, etc. are mentioned.

In the following Examples, although the chemical method of imidation is given, this invention is not limited to this.

Looking at one example of the preparation of a polyimide film using a specific chemical method of imidization, the prepared polyamic acid solution is reacted with a dehydrating agent to form a gel film having at least a portion of the polyamic acid having polyisoimide, and the obtained gel film After the imidization at 250 ~ 400 ℃ is a method of secondary heat treatment at 400 ℃ or more.

Thus obtained polyimide film is 0.25 ~ 90.25 mol% of repeating units represented by Formula 1, 0.25 ~ 90.25 mol% of repeating units represented by Formula 2, 0.25 ~ 90.25 mol% of repeating units represented by Formula 3 and Formula 4 It comprises a polyimide having a molecular weight of 5,000 to 10,000,000 irregularly arranged linearly, including 0.25 to 90.25 mol% of the repeating units indicated.

Such polyimide film is not limited in terms of thickness but is preferably in the range of 10 to 300 mu m, preferably in the range of 12 to 225 mu m.

On the other hand, the polyimide film of the present invention may be a dispersion of the inorganic particles, the dispersion of the inorganic particles on the film to prepare a polyamic acid, and then mixed by dispersing the inorganic particles therein, from which the polyimide film It can be carried out through the manufacturing method.

Here, the inorganic particles may be one or more selected from silica, quartz powder, titanium oxide, aluminum oxide, zircon powder, organo clay, magnesium oxide, calcium carbonate and zinc oxide having a particle size of 0.1 to 10 μm. It is preferably mixed so as to be 0.001 to 10 parts by weight based on 100 parts by weight of the total acid content of the total acid.

If the size of the inorganic particles to be dispersed is larger than 10 μm, the inorganic particles may protrude on the polyimide film and affect appearance and physical properties. In addition, when the content exceeds 10 parts by weight based on 100 parts by weight of the total solid content of the polyamic acid, finely dispersed particles may be generated due to difficulty in dispersing and may act as a defect in the polyimide film.

Dispersing such a suitable size of particles may increase the tensile modulus of the polyimide film to provide a polyimide film having excellent bending resistance.

The polyimide film of the present invention thus obtained satisfies the property that the dimensional strain after standing for 24 hours at 50 ° C. and 60% RH is 1.0% or less.

In addition, it satisfies the characteristic that the elongation at break is 20% or more and the difference between the elongation at break in the fixed direction and the elongation at break in the direction perpendicular to the tenter is 30% or less. Here, the difference between the elongation at break in the fixed direction and the elongation at break in the tenter is a variable that can define the uniformity of the mechanical strength of the film. If this value is more than 30%, the mechanical strength in the film is increased. It shows that there is an uneven problem.

The polyimide film of the present invention also has an average linear thermal expansion coefficient of 10 to 30ppm at 100 ° C or more and 200 ° C or less, and satisfies the characteristics that the dimensional strain is 0.1% or less and the glass transition temperature is 250 ° C or more after 1 hour of holding at 250 ° C. The average coefficient of thermal expansion is an appropriate value in combination with copper foil, and satisfies the dimensional strain of 0.1% or less after maintaining at 250 ° C. for 1 hour, and the glass transition temperature of 250 ° C. or higher indicates that the film has excellent heat resistance. Support the point.

On the other hand, the polyimide film of this invention shows the outstanding flex resistance with 100,000 times or more of bending resistance measured using the flex resistance test machine based on IPC-TM-650, 2.4.3.

Such a polyimide film of the present invention can be used for the production of a metal laminate, and preferably has properties useful as a base film of a copper foil laminate or a base film of an FPC.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited by these Examples.

The abbreviation used in each example is as follows.

PMDA: Pyromellitic dianhydride

BTDA: 3,4,3`, 4`-benzophenone tetracarboxylic dianhydride

BPDA: 3,4,3`, 4`-biphenyl tetracarboxylic dianhydride

ODA: 4, 4'-diamino phenyl ether

p-PDA: p-phenylene diamine

DABA : 4-Amino- N- (4-aminophenyl) benzamide

TPER: 1,3-bis (4-aminophenoxy) benzene

Synthesis Example

The polyamic acid was synthesized according to a conventional method using p-PDA or ODA, TPER, DABA as diamines, and PMDA, BTDA or BPDA as dianhydrides in compositions and contents as shown in Table 2 below. In Table 2, the content is mole%.

A polyamic acid was prepared using diamines and dianhydrides in a 1: 1 molar ratio. Polyamic acid was confirmed through elemental analysis. As an example, polyamic acid product confirmation results obtained through Synthesis Examples 1, 11, 15, and 20 are shown in Table 1 below. Table 1 shows the results of elemental analysis.

C O N H Synthesis Example 1 65.47% 23.69% 7.41% 3.40% Synthesis Example 11 64.96% 24.03% 7.48% 3.49% Synthesis Example 15 63.38% 26.35% 6.87% 3.36% Synthesis Example 20 58.87% 29.46% 8.58% 3.05%

Synthesis Example Diamines (100 mol%) Dianhydride (100 mol%) p-PDA ODA TPER DABA PMDA BTDA BPDA One - 20 - 80 10 90 - 2 - 20 - 80 50 50 - 3 - 20 - 80 90 10 - 4 - 20 - 80 10 - 90 5 - 20 - 80 50 - 50 6 - 20 - 80 90 - 10 7 - 50 - 50 10 90 - 8 - 50 - 50 50 50 - 9 - 50 - 50 90 10 - 10 - 50 - 50 10 - 90 11 - 50 - 50 50 - 50 12 - 50 - 50 90 - 10 13 - 90 - 10 10 90 - 14 - 90 - 10 50 50 - 15 - 90 - 10 90 10 - 16 - 90 - 10 10 - 90 17 - 90 - 10 50 - 50 18 - 90 - 10 90 - 10 19 - 100 - - 100 - - 20 100 - - - 100 - - 21 - 50 50 - - 100 - 22 - - - 100 - - 100 23 - 100 - - - 100 - 24 - - 100 - 50 50 - 25 100 - - - - 50 50

<Examples 1-18>

To each of the polyamic acid solutions obtained in Synthesis Examples 1 to 18, pyridine was added in an amount more than stoichiometric as a dehydrating agent, stirred uniformly, calcined on a SUS plate, cast to a predetermined thickness, and then cast to a predetermined thickness. Hot air dried at 30 to 60 minutes. Thereafter, the film was pulled off from the SUS plate and heat-dried at 250 ° C to 400 ° C for 10 to 30 minutes in a state where four sides were fixed, thereby obtaining a polyimide film having a thickness of 25 µm.

<Comparative Examples 1-7>

Using a polyamic acid obtained in Synthesis Examples 19 to 25, a polyimide film having a thickness of 25 μm was obtained in the same manner as in Example 1.

<Examples 19-21>

To each polyamic acid obtained in Synthesis Examples 2, 7, 15, SiO ₂ particles (Gasil 35M, manufactured by Crossfield) were added to 5.0 parts by weight with respect to 100 parts by weight of the polyamic acid solids content and homogenizer (T25). basic, manufactured by IKA LABORTECHNIK) at 9500 rpm for 5 minutes.

Using the prepared crude liquid, a polyimide film having a thickness of 25 μm was obtained in the same manner as in Example 1.

<Examples 22-24>

To the polyamic acid obtained in Synthesis Examples 2, 7, 15, TiO ₂ particles (R700, manufactured by DuPont) were added to 5.0 parts by weight based on 100 parts by weight of the polyamic acid solids content and homogenizer (T25 basic, IKA). LABORTECHNIK Co., Ltd.) was dispersed at 9500 rpm for 5 minutes.

Using the prepared crude liquid, a polyimide film having a thickness of 25 μm was obtained in the same manner as in Example 1.

For the films obtained through the above Examples and Comparative Examples, the dimensional strain, the elongation at break, the average coefficient of thermal expansion, the flex resistance and the glass transition temperature were measured and the results are shown in Table 3 below.

Specific evaluation method is as follows.

(1) dimensional strain

In this L ₀ by measuring the dimensions with a three-dimensional non-contact type measuring instrument with respect to the obtained film, and the contrast, to separate after the film was 24 hours at 50 ℃, 60% RH, in accordance with the same method of measuring the dimensions were as L _1. Dimensional strain was measured based on the following equation. This is called 'dimension strain-RH'.

Dimensional Strain-RH (%) = L ₁ -L ₀ / L ₀ × 100

In addition, based on the same method, after maintaining the obtained film at 250 degreeC for 1 hour, the dimensional strain was measured. This is called 'dimension strain-HT'.

(2) Elongation at break: Measured according to ASTM-D882. At this time, the elongation at break in the fixed direction in the tenter and the elongation at break in the vertical direction thereof were respectively measured and the difference was also measured.

(3) Average Coefficient of Thermal Expansion: Using TMA8140 manufactured by Hakki Electric Co., Ltd., the temperature was raised at a rate of 10 ° C. for 1 minute in the presence of nitrogen, and the value at 100 to 200 ° C. was measured and determined.

(4) flex resistance

Based on IPC-TM-650, 2.4.3, it measured using the bending resistance test machine (made by the hard test company).

(5) glass transition temperature

DSC was used to measure the glass transition temperature.

Dimensional strain (%) Elongation at break Average Coefficient of Thermal Expansion (ppm) Glass transition temperature (℃) Flex resistance (times) RH HT Elongation at Break (%) Elongation at Break Difference (%) Example One 0.5 0.02 40 10 15 350 100,000 2 0.3 0.03 45 13 20 300 120,000 3 0.6 0.05 48 14 18 350 120,000 4 0.5 0.05 56 13 20 350 150,000 5 0.7 0.03 38 15 15 360 120,000 6 0.5 0.06 46 16 22 380 150,000 7 0.3 0.02 50 20 20 350 130,000 8 0.3 0.02 57 20 25 320 100,000 9 0.4 0.03 60 20 18 350 130,000 10 0.5 0.06 55 23 19 330 130,000 11 0.3 0.02 45 15 16 380 140,000 12 0.3 0.03 49 17 20 300 150,000 13 0.1 0.01 40 20 25 350 100,000 14 0.6 0.03 46 21 20 355 130,000 15 0.4 0.02 47 9 19 350 120,000 16 0.6 0.05 55 10 28 360 130,000 17 0.7 0.08 54 21 20 355 150,000 18 0.9 0.08 52 22 25 360 130,000 19 0.3 0.04 50 20 20 350 140,000 20 0.6 0.05 45 23 18 330 140,000 21 0.4 0.03 39 10 16 350 130,000 22 0.6 0.06 34 13 15 330 130,000 23 0.7 0.08 32 16 20 380 150,000 24 0.5 0.06 45 16 20 350 140,000 Comparative Example One 0.9 1.0 19 30 35 300 100,000 2 1.2 1.6 21 35 40 250 90,000 3 1.5 2.0 25 35 30 300 80,000 4 1.5 1.7 10 39 35 300 90,000 5 1.2 1.4 16 32 40 320 40,000 6 1.4 1.6 19 34 30 330 80,000 7 2.0 1.7 20 39 35 350 60,000

As shown in Table 1, the polyimide film of the present invention is excellent in dimensional stability and heat resistance compared to the polyimide film of the comparative example, high elasticity, the coefficient of linear expansion does not lower than the coefficient of copper expansion (Copper), bending resistance and the like It can be confirmed that it is excellent. In particular, in the case of the polyimide film in which the inorganic particles are dispersed as shown in Examples 19 to 24, it can be seen that the flex resistance and the like are further improved in view of Examples 2, 7 and 15.

<Examples 25 to 29 and Comparative Examples 8 to 12>

Using each polyimide film obtained from the said Examples 1-5 and Comparative Examples 1-5, the sputter type polyimide / metal laminated body was produced in the following procedure, and the evaluation was performed. The obtained polyimide / metal laminated body was set to Examples 25-29 and Comparative Examples 8-12, respectively.

Each polyimide film obtained in Examples 1 to 5 and Comparative Examples 1 to 5 was used, using a sputtering machine (Type SHSP manufactured by Showa), equipped with an ion gun (model NPS-3000FS) manufactured by IONTECH. First, nickel was laminated to a thickness of 100 μm, and copper was subsequently laminated to a thickness of 2,000 μm to be referred to as a metal layer A1. Furthermore, a polyimide / metal laminate as a sputter-type two-layer copper clad substrate was formed by forming a copper layer (thickness 15 μm) as the plating metal layer by electrosulfate electroplating (cathode current density 2A / dm 2, plating time 40 minutes). (40 mu m total thickness) was prepared.

In the obtained polyimide / metal laminate, a metal layer was etched to obtain a 1 mm wide wiring pattern, which was then exposed to an environment of 121 ° C. and 100% RH for 96 hours and then left at 150 ° C. for 50 hours ( The adhesion strength between the polyimide / metal after the heat load) was measured by 90 ° peel of the pattern width of the wiring pattern formed on the metal layer according to JIS C-648, and compared with the adhesion strength in the state. . The results are shown in Table 4 below.

Polyimide film  Contact strength State (常態) (N / cm) After PCT (N / cm) After heat exposure (N / cm) Example 25 Example 1 0.8 0.8 0.7 26 Example 2 1.2 1.1 0.8 27 Example 3 1.5 1.3 1.0 28 Example 4 0.7 0.65 0.6 29 Example 5 1.0 0.85 0.7 Comparative Example 8 Comparative Example 1 0.7 0.2 <0.1 9 Comparative Example 2 0.8 0.3 <0.1 10 Comparative Example 3 1.2 0.4 <0.1 11 Comparative Example 4 1.3 0.3 <0.1 12 Comparative Example 5 0.7 0.3 <0.1

As described in detail above, according to the present invention, a mixture of ODA and DABA is mixed as diamines, and PMDA and BPDA or BTDA are mixed as dianhydrides to prepare polyamic acid irregularly arranged in a linear shape, and then molded into a film. One polyimide film has excellent dimensional stability, high elasticity and linear expansion coefficient that does not fall below the copper coefficient of copper. It doesn't compromise its properties, so it can respond to increasingly sophisticated electronics.

Claims (10)

0.25 to 90.25 mol% of the repeating unit represented by the following Chemical Formula 1, 0.25 to 90.25 mol% of the repeating unit represented by the following Chemical Formula 2 0.25 to 90.25 mol% of the repeating unit represented by the following Chemical Formula 3 and the repeating unit represented by the following Chemical Formula 4 Polyimide film consisting of polyimide having a molecular weight of 5,000 to 10,000,000, including 0.25 to 90.25 mol%. Formula 1

Formula 2

Formula 3

Wherein Ar is

Is displayed. Formula 4

Wherein Ar is

Is displayed. The polyimide film of claim 1, wherein the polyimide film is formed by dispersing inorganic particles. The method of claim 2, wherein the inorganic particles are one or more selected from silica or quartz powder, titanium oxide, aluminum oxide, zircon powder, organo clay, magnesium oxide, calcium carbonate and zinc oxide having a particle size of 0.1 to 10 ㎛. Polyimide film made into. The polyimide film according to claim 1, wherein the dimensional strain after standing for 24 hours at 50 ° C. and 60% RH is 1.0% or less. The polyimide film according to claim 1, wherein the elongation at break is 20% or more, and the difference between the elongation at break in the fixed direction and the elongation at break in the direction perpendicular to the tenter is 30% or less. The polyimide film of claim 1, wherein the average coefficient of linear thermal expansion in the range of 100 to 200 ° C is 10 to 30 ppm, the dimensional strain is 0.1% or less, and the glass transition temperature is 250 ° C or more after 1 hour of holding at 250 ° C. . The polyimide film according to claim 1, wherein the bending resistance measured by a bending resistance tester according to IPC-TM-650, 2.4.3 is 100,000 or more times. A metal laminate comprising the polyimide film of claim 1. 9. The metal laminate of claim 8, wherein the polyimide film is included as a base film. 10. The method according to claim 8 or 9, wherein the metal laminate is exposed to an environment of 121 DEG C and 100% RH for 96 hours after measuring the adhesion strength between the 1 mm wide wiring pattern and the polyimide film obtained by etching the metal layer. A metal laminate, wherein the adhesive strength is maintained at 50% or more of the adhesive strength before being exposed to this environment.