KR101758510B1

KR101758510B1 - Fe-Ni ALLOY METAL FOIL HAVING EXCELLENT FLEXIBILITY AND STRENGTH

Info

Publication number: KR101758510B1
Application number: KR1020150184283A
Authority: KR
Inventors: 정관호; 김기수; 김홍준; 이재곤
Original assignee: 주식회사 포스코
Priority date: 2015-12-22
Filing date: 2015-12-22
Publication date: 2017-07-17
Also published as: KR20170075134A

Abstract

An Fe-Ni alloy foil excellent in flexibility and a manufacturing method thereof are disclosed. One aspect of the present invention is an Fe-Ni alloy foil manufactured by an electroforming (EF) method and having a thickness of 100 탆 or less (excluding 0 탆), wherein the alloy foil contains, by weight% 46%, the remainder Fe, and inevitable impurities, wherein the alloy foil has a maximum radius of curvature of 2 mm or less in the elastic region and is excellent in flexibility and stiffness.

Description

FIELD OF THE INVENTION [0001] The present invention relates to an Fe-Ni alloy foil excellent in flexibility,

The present invention relates to an Fe-Ni alloy foil excellent in flexibility.

Alloy foils have been developed for various applications and are widely used in the home / industry. For example, aluminum foil is widely used for domestic and cooking purposes, and stainless steel foil is mainly used as a building interior material or exterior material.

Electrolytic copper foil is widely used as a printed circuit board (PCB) circuit, and recently it has been focused on small-sized products such as notebook computers, personal digital assistants (PDAs), e-books and mobile phones .

In addition, special alloy foils are also being produced. Among them, Fe-Ni alloy foils have low coefficient of thermal expansion (CTE) and are used as encapsulants for organic light emitting diodes (OLED) And may be used as an element substrate or the like. Furthermore, the negative electrode current collector and the lead frame of the secondary battery are attracting attention.

Rolling and electroforming are widely known as methods for producing the Fe-Ni alloy foil.

Among them, the rolling method is a method of casting copper (Cu), aluminum (Al), Fe and Ni into an ingot, and then rolling and annealing to obtain an alloy foil. The Fe-Ni alloy foil produced by such a rolling method has a high elongation percentage and a smooth surface, which is advantageous in that cracks do not easily occur.

However, it is difficult to manufacture a wide-width foil having a width of 1 mm or more due to facility restrictions during manufacture, and it is disadvantageous in that it takes too much manufacturing cost due to repetition of numerous rolling processes. Even if the alloy foil is produced by the rolling process while taking the disadvantage in terms of the manufacturing cost, the average crystal grain size of the structure is low, the mechanical properties are poor, the Young's modulus is large and the yield strength is low There is a disadvantage that the flexibility is poor.

On the other hand, the electrolytic solution is supplied with electrolytic solution through a liquid supply nozzle in a gap surrounded by a pair of circular arc-shaped cathodes opposed to a rotating cylindrical negative electrode drum installed in an electrolytic bath, The alloy is electrodeposited, peeled and wound to produce an alloy foil.

The Fe-Ni alloy foil manufactured by this electroforming method has an advantage that the average grain size is fine and excellent in mechanical properties, and the Young's modulus is relatively small and the yield strength is high, The manufacturing cost is low and the manufacturing cost is low.

As a substrate and an encapsulant applied to the flexible electronic device, excellent flexibility is required in consideration of workability and workability. However, since the flexible alloy foil such as copper, aluminum, Fe-Ni alloy and the like has a large maximum curvature in the elastic region, it is easily deformed by external force and can not be applied to a flexible electronic device. The average grain size is easily deformed by external impact or abrasion, which has the disadvantage of poor mechanical properties, that is, low rigidity.

An object of the present invention is to provide an Fe-Ni alloy foil excellent in flexibility.

The object of the present invention is not limited to the above description. Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

The present invention relates to a Fe-Ni alloy foil, which comprises 34 to 46% by weight of Ni, the balance Fe and unavoidable impurities, has a thickness of 100 占 퐉 or less (excluding 0 占 퐉) and has a maximum radius of curvature And an Fe-Ni alloy foil excellent in flexibility having a thickness of 2 mm or less.

The alloy foil has an average grain size of 5 to 40 nm.

The alloy foil has a yield strength of 800 MPa or more and a tensile strength of 900 MPa or more.

The present invention also provides a method of producing a Fe-Ni alloy foil having excellent flexibility, wherein the thickness is 100 탆 or less (excluding 0 탆) by electroforming (EF) : 34 to 46%, the balance Fe and unavoidable impurities, and stabilizing the alloy foil at a heat treatment temperature of 300 to 345 DEG C for 5 to 30 minutes to prepare a heat treated alloy foil .

The Fe-Ni alloy foil manufactured by the electroforming method may have a crystal grain size of 5 to 12 nm.

The heat-treated Fe-Ni alloy foil may have a grain size of 12 to 40 nm.

The Fe-Ni alloy foil according to the present invention has excellent flexibility and rigidity and can be suitably applied to substrates for flexible electronic devices and encapsulants for organic light emitting diodes (OLEDs).

1 is a graph showing FWHM obtained by X-ray diffraction according to a comparative example of the present invention.

As described above, alloy foils, which are usually produced by rolling, especially rolling envelopes, rolled aluminum foils, and electroformed copper foils produced by electroforming have low yield strength and have a very large maximum radius of curvature in the elastic region .

On the other hand, the Fe-Ni alloy foil manufactured by the electroforming method has an advantage that the average grain size is fine and the mechanical properties are excellent (the strength is very high), and the maximum radius of curvature in the elastic region is relatively And it is also possible to manufacture it with a low manufacturing cost, which is advantageous in that the manufacturing cost is low.

However, the Fe-Ni alloy foil manufactured by the electroplating method and the Fe-Ni alloy foil manufactured by the rolling method, the copper foil, and the aluminum foil have a permanent deformation when a warp is applied at a certain radius of curvature There is a problem in that it is used as a substrate of a flexible electronic device or a supporting substrate material because of its large radius.

Furthermore, the Fe-Ni foil manufactured by the electroforming method has a lower modulus of elasticity than that of the conventional rolled material, so that the maximum radius of curvature in the elastic region is small, but there is still a need for improvement.

Accordingly, the present inventors have intensively studied to solve the above problems, and as a result, they have led to the present invention. Hereinafter, the present invention will be described in detail.

The present invention provides a Fe-Ni alloy foil. The Fe-Ni alloy foil of the present invention preferably has a thickness of 100 mu m or less (excluding 0 mu m) and contains Fe in an amount of 34 to 46% by weight, Fe, and unavoidable impurities.

When the Ni content is excessively low, there is a problem that the coefficient of thermal expansion sharply increases, and the Tc (Curie temperature) is lowered and the recrystallization of the structure occurs rapidly during the heat treatment, so that the abnormal grain growth, There is a possibility that the effect of improving the flexibility is not sufficient and the uniformity may not be exhibited. Therefore, the Ni content is preferably at least 34 wt%, more preferably at least 35 wt%, and even more preferably at least 36 wt%.

On the other hand, if the content is too high, the coefficient of thermal expansion of the alloy foil becomes too large as compared with glass and the like, thereby causing a problem in utilization as an encapsulating material for an electronic material substrate and an organic solar cell. There is a concern. Therefore, the Ni content is preferably 46 wt% or less, more preferably 44 wt% or less, and even more preferably 42 wt% or less.

The remainder of the present invention is Fe. However, in the ordinary manufacturing process, impurities which are not intended from the raw material or the surrounding environment may be inevitably incorporated, so that it can not be excluded. These impurities are not specifically mentioned in this specification, as they are known to any person skilled in the art of manufacturing.

The Fe-Ni alloy foil of the present invention has an advantage that the maximum radius of curvature in the elastic region is 2 mm or less, more preferably 1.5 mm or less, and is extremely excellent in flexibility.

As a result, we have found that the flexibility of the Fe-Ni alloy foil is an important factor in ensuring flexibility of the fine grain size control of the alloy foil, which is superior to that of the Fe-Ni alloy foil .

According to an embodiment of the present invention, the size of the fine crystal grains is preferably 40 nm or less. If the size of the fine grains is more than 40 nm, the stabilization heat treatment proceeds excessively and the recrystallization of the structure occurs abruptly, so that the abnormal grain growth starts to appear, the yield strength becomes low, the Young's modulus becomes large, May be deteriorated. The smaller the number of such crystal grains, the more preferable is 40 nm or less. On the other hand, the alloy foil produced by the electric pole has a fine crystal grain size, and has a size of 12 nm or more in consideration of crystal grain growth by the stabilization heat treatment.

On the other hand, when the average grain size is made finer, excellent strength can be secured. Particularly, when the average grain size of the Fe-Ni alloy foil is controlled to 40 nm or less (excluding 0 nm), an excellent tensile strength of 1,000 MPa or more can be secured. Here, the average grain size refers to an equivalent circular diameter of the particles detected by observing a section of the alloy foil.

The Fe-Ni alloy foil of the present invention as described above is preferably one produced by the electroforming method. The Fe-Ni alloy foil is produced by a rolling method and a rolling method, but it is preferable that the alloy foil is manufactured by the rolling method of the present invention. When the alloy foil is manufactured by the rolling method, the average grain size of the structure is not favorable for embodying the present invention because it has a large mechanical property and has a large elastic modulus and a low yield strength so that flexibility is poor . On the other hand, the metal foil by the electric filament is suitable for obtaining the alloy foil of the present invention because of its small grain size and excellent mechanical properties.

At this time, it is preferable that the Fe-Ni alloy foil obtained by the electroforming method of the present invention is an Fe-Ni alloy foil containing Ni in the range of 34 to 46% by weight and the balance Fe and unavoidable impurities.

The alloy foil having the above composition is obtained by electrolytic casting by electroforming from an electrolytic solution containing iron and nickel. The electrolytic solution may be composed of 1 to 40 g / L of iron and 5 to 80 g / L of nickel.

At this time, for the electroforming, a current is applied so that the current density is in the range of 1 to 80 A / dm ² under the condition of supplying the electrolytic solution having a pH of 1.0 to 5.0 and a temperature of 40 to 90 ° C at a flow rate of 0.2 to 5 m / .

By performing electroforming under these conditions, an Fe-Ni alloy foil containing 34 to 46% of Ni by weight%, the balance Fe and unavoidable impurities can be obtained, and an Fe-Ni foil having a grain size of 5 to 40 nm can be obtained Can be obtained.

The iron in the electrolytic solution may be dissolved in the form of a salt such as iron sulfate, ferric chloride or ferrous sulfate or may be supplied by dissolving the electrolytic iron and the iron powder in hydrochloric acid or sulfuric acid. The nickel in the electrolytic solution can be supplied in a salt state such as nickel chloride, nickel sulfate, and nickel sulfomethicone, or by dissolving ferronickel or the like in an acid.

Further, the electrolytic solution may contain additives which can be generally used, for example, 5 to 40 g / L of a pH stabilizer, 1.0 to 20 g / L of a stress relaxation agent and 5 to 40 g / L of a conductive adjuvant . At this time, boric acid or citric acid may be used as the pH stabilizer, and saccharin or the like may be used as the stress relaxation agent. Further, sodium chloride can be used as a conductive auxiliary agent.

The thickness of the Fe-Ni alloy foil manufactured by the electroforming method is not particularly limited and may be 100 탆 or less (excluding 0 탆), preferably 50 탆 or less (excluding 0 탆). However, when the thickness of the alloy foil is larger than the above range, there is a problem that the maximum radius of curvature in the elastic region increases in proportion to the thickness in particular. Therefore, .

According to an embodiment of the present invention, when the alloy foil is produced by the rolling method of the present invention as described above, the prepared alloy foil may have an average grain size of 5 to 12 nm, more preferably 7 to 10 nm Lt; / RTI > Here, the average grain size means an equivalent circular diameter of the particles detected by observing a section of the alloy foil.

In the present invention, the alloy foil obtained by electroforming is stabilized by heat treatment. When the average grain size of the alloy foil is less than 5 nm, the effect of stabilizing the structure by heat treatment is not sufficiently obtained. On the other hand, when the average grain size of the alloy foil is more than 12 nm, the strength of the Fe-Ni alloy foil may be excessively lowered by the stabilization heat treatment to be described later.

On the other hand, a method for producing an Fe-Ni alloy foil in which the Fe and Ni contents are properly controlled by the electroplating method and the average grain size is appropriately controlled can be produced by performing electroforming under the above-mentioned method and conditions.

Thereafter, the Fe-Ni alloy foil is subjected to stabilization heat treatment. The heat treatment contributes to improve the flexibility of the alloy foil through the stabilization of the structure. It is preferable that the heat treatment temperature of the stabilization heat treatment is performed at 300 to 350 ° C. If the stabilization heat treatment temperature is less than 300 ° C, the structure stabilization is insufficient and the effect of improving the flexibility of the alloy foil by the stabilization heat treatment may be insufficient.

On the other hand, when the stabilization heat treatment is performed at a temperature exceeding 345 DEG C, recrystallization of the tissue occurs abruptly to cause an abnormal phenomenon such as abnormal grain growth and circular deformation, and the average crystal grain size Not only the mechanical properties are reduced but also the elastic modulus is large and the yield strength is low so that the effect of improving the flexibility is insufficient and there is a possibility that the mechanical properties are not uniformly displayed. Therefore, the stabilization heat treatment is preferably performed at a temperature in the range of 300 to 345 ° C as described above, and more preferably at 300 to 330 ° C.

The stabilization heat treatment time is preferably 5 to 30 minutes. When the stabilization heat treatment time is less than 5 minutes, the structure stabilization is insufficient and the effect of improving the flexibility of the alloy foil by the stabilization heat treatment may be insufficient. On the other hand, when the stabilization heat treatment time is longer than 30 minutes, the recrystallization of the tissue occurs rapidly There is a possibility that not only the effect of improving the flexibility but also the uniformity may not be exhibited in addition to the abnormal grain growth and circular deformation. It is more preferable to perform this stabilization heat treatment for 7 to 20 minutes, and more preferably to perform for 9 to 15 minutes.

Example

Hereinafter, the present invention will be described more specifically by way of examples. It should be understood, however, that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. do.

Comparative Example 1 to 3, Example 1 to 3

A pH stabilizer of 10 g / L, a stress relieving agent of 2 g / L, and a conductive additive of 25 g / L, and having a pH of 2.5, a current density of 40 A / dm ² , a plating solution temperature of 60 ° C Type Fe-Ni alloy foil was produced by drum-type electroforming under the conditions of the Fe-42 wt% Ni Fe-Ni alloy foil.

The prepared Fe-Ni alloy foil had a thickness of 20 mu m and an average grain size of 7.1 nm (Comparative Example 1).

Then, the prepared Fe-Ni alloy was subjected to stabilization heat treatment under the conditions shown in Table 1 (Examples 1 to 3, Comparative Examples 2 and 3).

Then, the average grain size, Young's modulus, maximum radius of curvature in the elastic region and yield strength of the Fe-Ni alloy foil subjected to the stabilization heat treatment were measured, and the results are shown in Table 1 below.

Remarks Foil type
(Recipe / material) thickness
(탆) Stabilization heat treatment Average
Crystal grain
Size (nm) Young's modulus (GPa) Elastic Maximum Curvature Radius
(mm) surrender/
The tensile strength
(GPa) Temperature
(° C) time
(minute) Comparative Example 1 Jeonju Incheon 20 Untreated 7.1 100 2.56 0.8 / 1.3 Inventory 1 Jeonju Incheon 20 300 15 13.1 120 0.96 1.2 / 1.2 Inventory 2 Jeonju Incheon 20 350 15 33.1 125 1.14 1.1 / 1.2 Inventory 3 Jeonju Incheon 20 350 30 36.4 132 1.32 1.0 / 1.0 Comparative Example 2 Jeonju Incheon 20 400 15 94.2 140 2.33 0.7 / 0.7 Comparative Example 3 Jeonju Incheon 20 500 15 460.1 147 2.94 0.5 / 0.5 Comparative Example 4 Rolling envelope 20 Untreated Hundreds to thousands 150 3.50 0.6 / 0.6 Comparative Example 5 Chonju Copper 20 Untreated Hundreds to thousands 50 5.50 0.2 / 0.25 Comparative Example 6 Rolled aluminum 20 Untreated Hundreds to thousands 70 60 0.05 / 0.05

As can be seen from the above Table 1, the alloy foil of Comparative Example 1 in which the heat treatment was not performed exhibited a sharp maximum radius of curvature in the elastic region.

However, it can be confirmed that the alloy foil of Examples 1 to 3, in which the stabilization heat treatment was performed while satisfying all the conditions of the present invention, had a maximum radius of curvature of 2 mm or less in the elastic region and thus had excellent flexibility.

Further, in Examples 1 to 3, the average grain size was controlled within the range according to one embodiment of the present invention, and the yield strength and the tensile strength were excellent, showing excellent mechanical properties.

On the other hand, in the case of Comparative Examples 2 and 3, the stabilization heat treatment temperature was too high and the heat stability was poor.

On the other hand, in Comparative Example 4, the yield strength of the invar material produced through rolling was not high, but the Young's modulus was too high and the flexibility was poor. The average grain size of the alloy foil at this time is more than several hundreds of nm. This is because many heat treatments have been carried out during the rolling process.

Further, in Comparative Example 5, the copper foil produced through the electric pole was not so large in Young's modulus, but the flexural strength was too low due to the low yield strength. Comparative Example 6 was an aluminum foil produced by rolling, Although relatively small, the yield strength was too low to show the lowest flexibility.

On the other hand, the results of Full Width at Half Maximum (FWHM) obtained by X-ray diffraction in Comparative Example 1, Inventive Example 1 and Inventive Example 3 are shown in FIG. As can be seen from FIG. 1, the FWHM of the FCC {111} peak decreases as the stabilization heat treatment proceeds.

Since the average grain size is inversely proportional to the size of FWHM in the XRD results, the grain size tends to increase as the annealing proceeds.

From the result of FIG. 1, it can be seen that the size of the crystal grains through the heat treatment directly affects the physical properties of the Fe-Ni alloy foil, in particular, the Young's modulus and the yield strength. Therefore, the control of the proper grain size is a major factor determining the maximum radius of curvature .

Claims

As the Fe-Ni alloy foil,
Wherein the alloy foil contains, by weight%, 34 to 46% of Ni, the balance Fe and unavoidable impurities, the thickness is 100 占 퐉 or less (excluding 0 占 퐉)
Wherein the alloy foil has a circle equivalent diameter of average crystal grains of 12 to 40 nm and a maximum radius of curvature in the elastic region of 2 mm or less.

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The Fe-Ni alloy foil according to claim 1, wherein the alloy foil has a yield strength of 800 MPa or more.

The Fe-Ni alloy foil according to claim 1, wherein the alloy foil has a tensile strength of 900 MPa or more.

Ni alloy foil having a thickness of 100 mu m or less (excluding 0 mu m) by weight, an Fe-Ni alloy foil containing 34 to 46% Ni, and the balance Fe and unavoidable impurities by electroforming (EF) An alloy foil manufacturing step;
An alloy foil heat treatment step for preparing a heat-treated alloy foil by stabilizing the alloy foil at a heat treatment temperature of 300 to 345 DEG C for 5 to 30 minutes
Wherein the heat-treated alloy foil has a circle-equivalent diameter of crystal grains of 12 to 40 nm and a maximum radius of curvature in the elastic region of 2 mm or less.

6. The method for producing an Fe-Ni alloy alloy foil according to claim 5, wherein the Fe-Ni alloy foil obtained in the step of manufacturing the alloy foil by the electric pole has a circle equivalent diameter of crystal grains of 5 to 12 nm.

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