KR102065216B1 - Fe-Ni ALLOY FOIL WITH EXCELLENT FLEXIBILITY RESISTANCE - Google Patents

Abstract

The present invention relates to an iron-nickel alloy foil having excellent flex resistance. In the iron-nickel alloy foil of the present invention, the nickel content is 36 to 42 wt%, the residual carbon and the sulfur content are each 500 ppm or less, the surface roughness Ra is 1.5 µm or less at the drum surface and the solution surface, respectively, the tensile strength is 800 MPa or more, The average grain size is 50 nm or more, and the weight variation of the iron-nickel alloy foil is 3 g / m 2 or less. The iron-nickel alloy foil according to the present invention is not only high in strength but also excellent in bending resistance and can be used as a material for flexible displays. In addition, the iron-nickel alloy foil according to the present invention is capable of fine etching processing, it is possible to implement a high resolution.

Description

Fe-Ni ALLOY FOIL WITH EXCELLENT FLEXIBILITY RESISTANCE

The present invention relates to an iron-nickel alloy foil, and more particularly to an iron-nickel alloy foil excellent in flex resistance.

The flexible display is a next-generation display that can be transformed, such as being able to be folded or bent, unlike a flat panel display. The flexible display can increase space utilization by changing its shape, and has the advantage of being thin, light and unbreakable. Accordingly, the present invention can be applied to wearable smart devices such as smart phones, foldable IT devices, rollable IT devices, automotive displays, and digital signage. Flexible IT devices that can be folded or bent are expected to provide convenience to consumers by increasing portability and space utilization. In order to develop such next-generation IT devices, development of parts that can be modified such as flexible displays should be preceded.

Flexible displays are evolving into curved, bendable, rollable, and foldable stages, which are slightly curved depending on the degree of bending. Only the display of the (Curved) stage is commercialized (smartphone, smart watch, etc.).

The flexible display may be implemented in various ways, such as OLED, LCD, E-paper, etc., but in the industry, the OLED driving method is suitable for the flexible display, and product development using the same is being made.

A key component of flexible display production technology is the shadow mask, which is essential for high resolution. This mask, known as fine metal mask (FMM), is an essential component for producing high-resolution OLEDs with RGB (red, green, and blue) structures, and a shadow mask with a thickness of about 40 μm for making a resolution of 1 million pixels. Is needed. Since the mask is secured and flexible, heat shrinkage and expansion occur as the process is performed at a high temperature, it is essential to select a material having excellent thermal expansion characteristics. Korean Patent Publication No. 2016-0047193 has been filed as a technique for a conventional shadow mask.

In addition, an invar alloy (Fe-36% Ni), which is an iron-nickel (Fe-Ni) alloy system, is mainly used as a shadow mask material. The Invar alloy manufactured through the rolling process has high resolution due to manufacturing technology limitations (surface defects caused by inclusions and increased manufacturing cost) of shadow mask ultra-thin products (thickness of 18 µm or less), which is a key component that determines OLED display panel pixels. Upgrading is difficult.

On the other hand, the mask is thin in thickness, and many minute holes are drilled so that they are invisible by the manufacturing technique of the etching method. OLED panels are made by placing a mask on a panel substrate and vacuum depositing RGB phosphor organic materials. The thinner the mask and the finer the hole, the finer the hole can be deposited in place. The finer the hole, the higher the pixel. In addition, the mask swelling or stretching at high temperatures should be minimized.

On the other hand, it is possible to manufacture a thin iron-nickel alloy foil by the electroplating method rather than the conventional rolling method. However, when the thickness of the iron-nickel alloy foil is thin, the strength is accompanied, and various problems occur in the process due to cracking and tearing of the metal foil as well as deformation of the substrate during fabrication of the deposition mask.

Accordingly, there is a need for an iron-nickel electrode foil having a small thickness and excellent strength and flex resistance. In addition, excellent bending resistance and high tensile strength are required to secure dent resistance during handling in the etching process and the deposition process.

Korean Patent Publication 2016-0047193

The present invention provides an iron-nickel composite foil having excellent strength and flex resistance. The present invention also provides an iron-nickel composite foil having excellent strength and flex resistance, which can be used as a material for flexible displays.

According to one aspect of the present invention, the nickel content is 36 ~ 42wt%, the carbon and sulfur content is 500ppm or less, respectively, the balance of iron and inevitable impurities, the drum surface and the solution surface surface roughness (Ra) of 1.5㎛ each Hereinafter, an iron-nickel alloy foil having a tensile strength of 800 MPa or more, an average grain size of 50 nm or more, and a weight variation of the iron-nickel alloy foil of 3 g / m 2 or less is provided.

The tensile strength may be 800 MPa to 1200 MPa.

The average grain size may be 50nm to 100nm.

The iron-nickel alloy foil may have a crystal orientation of 20% or more.

The iron-nickel alloy foil may have a thermal expansion coefficient of 5 ppm / K or less.

The iron-nickel alloy foil may have a deviation of 1 wt% / m 2 or less of nickel.

The iron-nickel alloy foil may have a thickness of 18 μm or less.

The iron-nickel alloy foil may be used as a flexible display material.

The iron-nickel alloy foil according to the present invention is not only high in strength but also excellent in bending resistance and can be used as a material for flexible displays. In addition, the iron-nickel alloy foil according to the present invention is capable of fine etching processing, it is possible to implement a high resolution.

1 is a schematic view showing the electroplating apparatus used for producing the iron-nickel alloy foil of the present invention.

The inventors of the present invention have found that iron-nickel alloy foils satisfying a specific combination of physical properties among iron-nickel alloy foils have high strength and excellent flex resistance despite being thin in thickness, and have thus completed the present invention.

Iron-nickel alloy foil having high strength and excellent bending resistance according to one embodiment of the present invention contains 36 to 42 wt% nickel, 500 ppm or less of carbon and sulfur, and the balance of iron and inevitable impurities, and the surface of the drum surface and the solution surface. The roughness Ra is 1.5 µm or less, the tensile strength is 800 MPa or more, the average grain size is 50 nm or more, and the weight variation of the iron-nickel alloy foil is 3 g / m 2 or less. Hereinafter, all the physical properties of the alloy foil described in this specification are physical properties after heat treatment.

The nickel content in the iron-nickel alloy foil (hereinafter also referred to simply as 'alloy foil') is 36 wt% to 42 wt%. When the nickel content is low, there is a problem in that the coefficient of thermal expansion is sharply increased, so the nickel content is preferably 36wt% or more. However, when the content is excessively high and exceeds 42wt%, the thermal expansion coefficient of the alloy foil is too large compared to glass, there is a problem that can not be used as a flexible display material.

The contents of carbon and sulfur are each 500 ppm or less. When the carbon or sulfur content exceeds 500 ppm, in the deposition process of the alloy foil, fine fracture is formed while carbon becomes carbon dioxide and sulfur becomes sulfur dioxide by heat reaction.

Except for the nickel, carbon and sulfur contents described above, the remaining components are Fe. However, in the conventional manufacturing process, impurities which are not intended from the raw material or the surrounding environment may be inevitably mixed, and thus cannot be excluded. Since these impurities are known to those skilled in the art, all of them are not specifically mentioned in the present specification.

The alloy foil of this application is 1.5 micrometers or less in surface roughness Ra of a drum surface and a solution surface, respectively. In order to minimize the difference in etching depth during the etching process, the surface roughness Ra of the drum surface and the solution surface should be 1.5 µm or less, respectively. The drum surface refers to the surface in contact with the drum of the electroforming apparatus, and the solution surface refers to the surface in contact with the solution and the opposite surface of the drum surface.

The alloy foil of the present application has a tensile strength of 800 MPa or more, preferably 800 to 1200 MPa. If the tensile strength is less than 800 MPa, it is difficult to secure dent resistance during handling in the etching and deposition processes. The higher the tensile strength is, the more preferable and the upper limit is not particularly limited. However, in order to increase the strength to 1200 MPa, the content of saccharin must be increased. In this case, the alloy foil is not continuously manufactured. The upper limit may be about 1200 MPa.

The average grain size is an average grain size after heat treatment, the alloy foil of the present application has an average grain size of 50nm or more, preferably 50nm to 100nm. It is preferable that the average grain size is in the above range in view of excellent bending resistance and tensile strength. If the average grain size is less than 50 nm, the bending resistance is low. If the average grain size is more than 100 nm, the tensile strength is lowered, which is not preferable.

The average grain size of electrodeposition foil is 50 nm or less. However, the grains in the heat-treated foil having completed the heat treatment process grow to an average grain size of 50 nm or more. In general, in the case of having fine grains, the hardness and strength are high, but have a low elongation. However, in order to have excellent bending resistance, the average grain size should be 50 nm or more.

The alloy foil of this application is 3 g / m <2> or less in weight variation. When the weight deviation exceeds 3 g / m 2, stress is concentrated in the high weight portion, thereby decreasing the flatness of the iron-nickel alloy foil, resulting in uneven etching and risk of fracture. The smaller the weight deviation is, the better and the lower limit is not particularly limited.

Iron-nickel alloy foil of the present application is preferably 20% or more, more preferably 20% to 30% change in crystal orientation.

The surface roughness Ra of the iron-nickel alloy foil does not change by the heat treatment process, but crystals grow in a low temperature range. Grain growth not only changes the grain size but also changes in the texture of the aggregates. When the crystal orientation changes less than 20%, there is a problem that the surface curl increases due to the crystal structure change. If the surface curl is increased, there is a problem that cannot be commercialized. In addition, when more than 30% occurs, the shape of the pattern is incorrect in the etching process due to the change in the plate shape of the alloy foil, it is impossible to commercialize the low uniformity.

In the crystal orientation, when the (111) plane peak intensity is I (111) and the (200) plane peak intensity is I (200) among the peaks obtained by X-ray diffraction analysis on the electrodeposited foil surface, I (200) / I (111).

The iron-nickel alloy foil of the present application preferably has a coefficient of thermal expansion (CTE) of 5 ppm / K or less. If the coefficient of thermal expansion exceeds 5 ppm / K, it is not preferable due to defects such as color bleeding due to the dimensional difference between the substrate and the mask during the deposition process. The smaller the coefficient of thermal expansion, the better. The lower limit is not limited.

Furthermore, it is preferable that the iron-nickel alloy foil of this application is 1 wt% / m <^2> or less of a deviation of a nickel component. When the variation of the nickel component of the alloy foil exceeds 1wt% / m ² , the coefficient of thermal expansion becomes large, and thus, a problem of the difference in the dimensions of the substrate and the mask may occur during the deposition process.

The iron-nickel alloy foil of the present application has a thickness of 18 µm or less, preferably 4 µm to 18 µm. When the thickness of the alloy foil exceeds 18 µm, it is not preferable to use it as a high resolution material, and if it is less than 4 µm, the yield is not preferable because of a problem in handling of the etching process.

The iron-nickel alloy foil of the present invention may be used as a flexible display material (eg, a mask, a substrate, etc.), but is not particularly limited thereto.

Iron-nickel alloy foil of the present application that satisfies the above properties can be produced by the electroforming method. Hereinafter, the manufacturing method of the iron-nickel alloy foil of this application by the electroplating method is demonstrated with reference to the electroplating apparatus of FIG.

In the electroforming method, the liquid supply unit 14 is opened by a gap surrounded by a rotating cylindrical cathode drum 12 installed in the electrolytic cell 11 of the electroplating apparatus of FIG. 1 and a pair of arc-shaped insoluble anodes 13 opposed thereto. It is a method of manufacturing the metal foil 1 which is electrodeposited foil by electrodepositing an iron-nickel alloy foil on the surface of the negative electrode drum 12 while supplying an electrolyte solution and flowing an electric current. In the present application, the iron-nickel alloy foil produced through the electroplating apparatus is referred to as 'electrode electrode foil', and the heat treated at a predetermined temperature condition is referred to as 'heat treated foil'.

The electrodeposition foil is a surface roughness, weight deviation, carbon content, sulfur content, texture ratio, thermal expansion coefficient of the electrodeposited foil according to the electroforming conditions, such as the composition, temperature, current density, pH, flow rate of the electrolyte according to the type and content of the additive , Factors such as tensile strength can be adjusted.

For example, the electrolyte may include additives such as iron, a nickel compound, a stress relaxer, a brightener, a pH stabilizer, and the like.

For example, the electrolyte may contain 5 to 20 g / L of iron ions, 20 to 50 g / L of nickel ions, 30 g / L or less (excluding 0) of sodium, 5 g / L or less (excluding 0) of boron, 1 to 1 100 ppm saccharin, greater than 5 ppm to less than 25 ppm polyphenylene sulfide (PPS) may be included.

The remaining components of the electrolyte is water as a solvent, water is not particularly limited, pure water, ultrapure water, purified water, distilled water and the like can be used, preferably ultrapure water can be used.

The concentration of iron ions and nickel ions in the electrolyte is determined according to the iron and nickel content in the iron-nickel alloy foil to be prepared. By adjusting to approximately the above range, iron-nickel alloy foil having a desired physical property and applicable to a desired use can be produced.

The iron ions may be used by dissolving in the form of salts such as iron sulfate, iron chloride, iron sulfperate, or by dissolving electrolytic iron and iron powder in hydrochloric acid or sulfuric acid. In addition, the nickel ion may be used in the form of a salt such as nickel chloride, nickel sulfate, nickel sulfamate, or by dissolving ferronickel in an acid.

Sodium in the electrolyte component is added to lower the cell voltage composed of a cathode, an anode, and an electrolyte by reducing the resistance of the electrolyte. The sodium component can preferably achieve the intended effect when added at 30 g / L or less. If the concentration of the sodium exceeds 30 g / L, the cell voltage is further lowered, but a red powder phenomenon occurs so that the target product cannot be manufactured. There is a problem. The sodium component may be provided by any material generally known to be formulated to provide the sodium component to the electrolyte, for example, sodium chloride, sodium carbonate, and the like may be used, but is not limited thereto.

The boron is a component added to maintain a constant pH of the electrolyte solution, and may be suitably added to have an intended pH range. For example, the pH can be adjusted by adding up to 5 g / L. The pH of the electrolyte is an important factor that affects not only the electrolyte itself but also the overall product characteristics. In particular, it is very important to maintain the pH at a constant value because the area around the cathode is a region where the local pH is easily changed. The boron component may be provided by any material generally known to be formulated to provide the boron component to the electrolyte, for example, boric acid may be used, but is not limited thereto.

Saccharin and PPS are added to lower the surface roughness and increase the tensile strength of the iron-nickel alloy foil. When the stress is concentrated on the plated surface during the production of the iron-nickel alloy foil through the electroforming method, it is discharged and interferes with crystallization of the adsorbed elements, resulting in a powdering phenomenon in appearance. You won't get it.

To prevent this, saccharin can be added as an additive to relieve stress. Saccharin may be added to exhibit a desired stress relaxation effect in the range of 1 to 100 ppm.

PPS is added to give a leveling effect in addition to the gloss effect during electrolytic plating, and further serves to lower the roughness of the plated tissue through interaction with saccharin. The PPS may be formulated to lower the surface roughness by the interaction in the range of more than 5ppm to less than 25ppm to exhibit a leveling effect.

PH of the electrolyte solution may be, for example, 1.0 ~ 3.0, the electrodeposition foil is easily prepared in this range of pH.

For example, possible to manufacture the electrodeposited foil to the temperature, the conditions of a flow rate of 10 ~ 100A / dm current density of ² and 10 ~ 100m ³ / hr at the time of manufacture electrodeposited foil with the pole device of Fig. 1, 45 ~ 70 ℃ have. If the current density is too low, there is a disadvantage that the work speed is slow, thereby reducing productivity. On the other hand, if the current density is too high, the stress increases, and the overvoltage required for the high current density increases, so that side reactions are relatively increased on the anode and cathode surfaces in addition to the main reaction. As a result, current efficiency is lowered, and there is a problem that deterioration of electrodeposits such as burning and hydrogen embrittlement occurs.

In addition, if the temperature is too high or the flow rate is too low, the nickel composition is low, while if the temperature is too low or the flow rate is too excessive, there is a problem that the nickel composition is increased.

For example, an electrodeposition foil is obtained under the above-mentioned electrolyte solution and electroforming conditions, and a heat treatment step is performed so that crystal grains of the electrodeposition foil are grown. The heat treatment step can be carried out by holding the reducing gas for 10 minutes or more, preferably 10 minutes to 60 minutes in the temperature range of 300 ~ 350 ℃ to suppress the surface oxidation and stabilize the structure of the alloy foil. More preferably, it is maintained for 20 to 40 minutes.

As the reducing gas, hydrogen, nitrogen, or a mixed gas (for example, a 2: 8 volume ratio of hydrogen: nitrogen) may be used.

When the heat treatment temperature is less than 300 ° C., there is a fear that the flex resistance due to insufficient structure stabilization may be reduced. On the other hand, when the temperature exceeds 350 ° C., shape change of the alloy foil due to rapid grain growth occurs, which is not preferable. In the case of the heat treatment time, if less than 10 minutes is locally heat treatment, if it exceeds 60 minutes, it is not preferable because the problem of tensile strength decrease due to accelerated surface oxidation of the alloy foil and grain growth.

A person skilled in the art can manufacture an iron-nickel alloy that satisfies the properties of the present application with reference to the electrolyte composition and electroforming conditions as exemplified above.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, it should be noted that the following examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. This is because the scope of the present invention is determined by the matters described in the claims and the matters reasonably inferred therefrom.

(Example)

The iron-nickel alloy foil was manufactured using the electroplating apparatus shown in FIG. The electrodeposited foil was prepared by supplying an electrolyte solution having a composition of Table 1 below at a flow rate of 35 m ³ / hr under a condition of pH 2.0 and a temperature of 57 ° C. and a current density of 30 A / dm ² . Thereafter, the resultant electrodeposited foil was subjected to heat treatment for 20 to 40 minutes at a temperature in the range of 300 to 350 ° C. while flowing a mixed gas (2: 8 volume ratio gas of hydrogen and nitrogen) at 20 L / m as a reducing gas. Nickel alloy foil was obtained.

The obtained heat-treated foil was subjected to the MIT bending test, and the physical properties and the number of MITs of the iron-nickel alloy foils prepared in Examples and Comparative Examples are shown in Table 2 below.

Evaluation of physical properties shown in Table 2 was performed in the following manner.

1. Surface Roughness

The surface roughness of the drum surface and the solution surface was the arithmetic mean roughness Ra, which indicates the roughness in the JIS B 0601-2001 standard, and was measured by a 3D profiler which is an optical non-contact surface roughness meter. At this time, the magnification was measured in the width direction of the iron-nickel foil surface at a total of 50 times the viewing angle lens and the objective lens magnification.

2. Tensile Strength

It was manufactured on the basis of ASTM-SUB and measured using a fine tensile tester on the basis of strain speed 1㎛ / sec.

3. Crystal orientation

The peak intensity of the (111) plane among the peaks obtained by X-ray diffraction analysis of the electrodeposited foil surface is called I (111), and the peak intensity of the (200) plane is called I (200). ) Percentage. Namely, crystal orientation (%) = [I (200) / I (111)] * 100

4. Average grain size

Using the full width at half maximum (FWHM) of the diffraction peaks by X-Ray diffraction analysis, the grain size of the electrodeposited foil and the heat treated foil was calculated using the Scherrer equation ^* . (* BDCullity; Elements of X-Ray diffraction, (2 ^nd ed., Addison-Wesley Pub., 1978) 102.)

Crystal size (d) = 0.9λ / (B cosθ), λ: X-ray wavelength, B: half width, θ: diffraction angle

The average grain size was analyzed using X-ray, and the same value was shown for both the drum face and the solution face.

5. MIT bend test

MIT bending test was done with the MIT bending test apparatus. In the bending test, the bending was repeated under the following conditions, and the number of times until the test piece was disconnected was determined as the number of bending.

Specimen size: ED 150mm * TD 12.5mm, Bending radius (R): 0.38mm, Bending angle: 90 ° Bending speed: 90 times / min, Load: 450g

6. Carbon, and sulfur content measurement

Carbon and sulfur content present in the alloy foil were measured using an Elemental Analyzer.

7. Measurement of weight deviation

The weight deviation of the alloy foil is to cut the alloy foil to a size of 50mm * 50mm, to prepare a specimen, and to measure the weight to convert the weight value of the alloy foil per unit area. Then, the process of cutting the specimen along the width and length direction was repeatedly performed. The weight value for each specimen was measured and then calculated by calculating the standard deviation.

8. Measurement of Nickel Content and Nickel Component Deviation The components of the nickel component were continuously measured using a fluorescent X-ray method. Fluorescence X-ray method is a method commonly used to measure the components of the elements constituting the specimen by measuring the intensity of the characteristic fluorescent X-rays emitted from the specimen after the primary X-rays incident on the specimen. At this time, the calibration curve In order to set, a standard specimen having a known component is used. In the present invention, five standard specimens of iron-nickel alloys are used. The content of the nickel component of the alloy foil was also measured using a fluorescent X-ray method.

9. How to measure the coefficient of thermal expansion (CTE)

Heat-treated alloy foils were analyzed for thermal expansion behavior using TMA (Thermo-Mechanical Analysis). It stabilized at 20 degreeC, hold | maintained for 1 minute, and heated it to 200 degreeC 5min / min, hold | maintained for 5 minutes, and cooled to 5 degreeC / min rate to 20 degreeC. CTE was calculated in the straight section of 30 ~ 100 ℃ descending while cooling.

Composition of electrolyte division Iron ions
(g / L) Nickel ion
(g / L) salt
(g / L) Boron
(g / L) saccharin
(ppm) PPS
(ppm) Example 1 13.17 43.78 21.29 2.89 50 15 Example 2 13.23 42.58 22.05 2.93 50 15 Example 3 12.78 44.39 21.98 2.79 50 15 Example 4 12.64 44.57 21.39 2.77 50 15 Example 5 13.13 43.00 20.49 2.95 50 15 Example 6 12.97 45.28 20.88 2.92 50 15 Example 7 13.61 47.26 21.19 2.91 50 15 Example 8 13.69 45.55 21.34 2.92 50 15 Comparative Example 1 13.94 44.17 30.5 2.82 50 15 Comparative Example 2 13.93 44.71 20.19 5.05 50 15 Comparative Example 3 14.04 44.48 21.19 2.78 102 15 Comparative Example 4 14.08 43.66 21.34 2.76 0.5 15 Comparative Example 5 12.73 44.43 22.72 2.54 50 2 Comparative Example 6 12.79 43.09 22.80 2.58 50 27 Comparative Example 7 13.61 47.26 31.0 2.76 50 4 Comparative Example 8 13.45 47.20 22.34 6.0 0.5 15

In the electrolyte of Table 1, iron ions were used as iron sulfate, nickel chloride as nickel ions, sodium chloride as sodium, boric acid as boron, and the balance was ultra pure water.

Properties of Iron-Nickel Alloy Foil division thickness
(Μm) Drum face
(Ra) Solution cotton
(Ra) Ni content
(wt%) carbon
content
(ppm) sulfur
content
(ppm) decision
Orientation
(%) Thermal expansion
Coefficient
(ppm / K)
weight
Deviation
(g / ㎡) Ni component
Deviation
(wt% / ㎡) Average grain size
size
(nm) Seal
burglar
(GPa) MIT
Count Example 1 18 1.2 1.5 36.5 200 400 27 3.71 2 0.5 84 1.3 602 Example 2 18 1.2 1.5 36.5 200 400 28 3.65 2 0.5 73 1.1 574 Example 3 18 1.2 1.0 38.0 300 400 27 4.33 2 0.4 85 1.0 558 Example 4 18 1.2 1.5 38.0 100 400 23 4.18 2 0.5 66 0.8 552 Example 5 18 1.2 1.5 40.0 200 100 23 4.43 2 0.4 77 1.1 546 Example 6 18 1.2 1.5 40.0 200 400 25 4.59 2 0.5 62 1.0 549 Example 7 18 1.2 1.0 41.2 200 400 27 4.77 2 0.5 52 0.9 560 Example 8 18 1.2 1.0 41.2 200 400 24 4.89 2 0.5 57 1.0 623 Comparative Example 1 18 1.2 2.0 36.5 200 600 21 4.13 2 0.4 61 0.7 464 Comparative Example 2 18 1.2 1.7 36.5 200 400 12 3.98 2 0.4 53 0.8 490 Comparative Example 3 18 1.2 1.5 38.0 500 400 11 4.53 2 0.5 55 0.9 495 Comparative Example 4 18 1.2 1.5 38.0 200 400 13 4.37 2 0.5 51 0.8 490 Comparative Example 5 18 1.2 2.0 40.0 200 400 19 4.60 2 0.5 60 1.0 463 Comparative Example 6 18 1.2 1.5 40.0 200 600 24 4.89 2 0.5 55 1.1 482 Comparative Example 7 18 1.2 1.5 41.2 600 400 18 4.97 2 0.5 52 0.7 488 Comparative Example 8 18 1.2 1.0 41.2 200 400 13 4.90 2 0.5 52 0.7 466

As can be seen from Table 2, the iron-nickel alloy foils according to the embodiment of the present invention records at least 500 times the MIT, whereas the iron-nickel alloy foils according to the comparative example is less than 500 times the MIT . From this, it can be seen that the iron-nickel alloy foil satisfying the physical properties of the present application exhibits excellent flex resistance.

1 ... electrodeposition 11 ... electrolytic cell
12 ... cathode drum 13 ... anode
14 ... liquid supply

Claims (8)

Nickel content is 36 ~ 42wt%, carbon and sulfur content is 500ppm or less each, and it contains residual iron and unavoidable impurities. Iron-nickel alloy foil whose average grain size is 50 nm or more, and the weight variation of iron-nickel alloy foil is 3 g / m <2> or less. The iron-nickel alloy foil of claim 1, wherein the tensile strength is 800 MPa to 1200 MPa. The iron-nickel alloy foil of claim 1, wherein the average grain size is 50 nm to 100 nm. The iron-nickel alloy foil according to claim 1, wherein the crystal orientation is 20% or more. The iron-nickel alloy foil according to claim 1, which has a coefficient of thermal expansion of 5 ppm / K or less. The iron-nickel alloy foil according to claim 1, wherein the nickel component has a deviation of 1 wt% / m 2 or less. Iron-nickel alloy foil of Claim 1 whose thickness is 18 micrometers or less. The iron-nickel alloy foil according to any one of claims 1 to 7, wherein the iron-nickel alloy foil is applied as a flexible display material.

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