Aluminum alloy foil, aluminum laminate, and method for producing aluminum alloy foil

Abstract

To provide an aluminum alloy foil having strength and elongation capable of improving workability during manufacturing and reducing wire breaking after manufacturing, about an aluminum alloy foil used in an etching circuit, in particular, in a printed wiring board, and excellent in high chemical solubility and cost.SOLUTION: An aluminum alloy foil having iron content of 0.5 mass% or more and less than 1.8 mass%, a silicon content of less than 1.5 mass%, and the balance made of aluminum and unavoidable impurities, containing an intermetallic compound having an equivalent circle diameter exceeding 0.1 μm and less than 3.0 μm of 3.0×105 pieces / mm2 or more, a predetermined KAM value of 0.8° or more and less than 1.4°is used.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aluminum alloy foil, an aluminum laminate, and a method for manufacturing an aluminum alloy foil.

Background Art

[0002] Printed wiring boards are used in electrical and electronic devices. For example, a resist ink is printed in a pattern on the surface of an aluminum foil laminated on a substrate to form a desired wiring shape, and then the foil is immersed in an etching solution to dissolve the portions where the resist ink is not printed, thereby manufacturing an aluminum foil in a wiring pattern.

[0003] Conventionally, 1000 series or 8000 series aluminum foils of JIS H4160 have been used for aluminum foils for printed wiring boards. However, the dissolution rate of these aluminum foils in the etching solution is slow, making high-speed processing difficult. Therefore, an aluminum alloy foil has been proposed that contains nickel (Ni), and one or two of zinc (Zn) and gallium (Ga) in the aluminum foil composition, and has enhanced solubility by increasing the potential difference between the compound containing aluminum (Al) and nickel (Ni) and the matrix phase (Patent Document 1).

[0004] By the way, aluminum foils for printed wiring boards generally remove rolling oil in the final annealing process after the cold rolling process to maintain the adhesive strength between the aluminum foil and the substrate and to enhance the flexibility of the aluminum foil itself. However, if the strength of the aluminum foil decreases too much in this final annealing process, productivity tends to deteriorate, such as the workability in printed wiring board manufacturing deteriorates and the risk of wiring disconnection in subsequent processes increases.

[0005] On the other hand, for example, in Patent Document 2, a technical proposal has been made that has high strength by finely dispersing an aluminum-manganese-iron (Al-Mn-Fe) -based compound, has excellent sensitivity in the etched portion, and has excellent etching solubility.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] By the way, in order to improve the productivity of printed circuit boards, it is required to further increase the dissolution rate. In recent years, the requirements for fine line etching have been increasing, and the risk of wire breakage tends to be higher. To reduce the risk of wire breakage, it is considered that high strength and elongation are required for aluminum foils. However, when conventional aluminum foils are finally annealed at a temperature at which rolling oil can be removed, they are significantly softened by recrystallization.

[0008] The tensile strength and 0.2% proof stress in Patent Document 2 are at most 124 N / mm 2 and 61 N / mm 2 respectively, which is not sufficient. Although Patent Document 2 does not disclose data such as the area ratio and number density representing the fine precipitation of compounds, it is presumed that the strength is improved by dispersion strengthening by finely dispersing Al - Mn - Fe - based compounds, but recrystallization is expected due to the final annealing. To obtain a higher strength than the aluminum alloy foil described in Patent Document 2, it is important to suppress recrystallization due to the final annealing.

[0009] In addition, using additive metals such as Ni and Mn in the composition of aluminum alloy foils is also desirable to avoid in terms of cost. Furthermore, the excessive addition of elements other than inevitable impurities such as Fe and silicon (Si) also affects the treatment cost of etching waste liquid.

[0010] Therefore, in the present invention, an object is to provide an aluminum alloy foil used for an etching circuit, particularly for an aluminum alloy foil used in a printed wiring board, which has improved workability during manufacturing and strength and elongation capable of reducing disconnection after manufacturing, and has high chemical solubility and excellent cost performance.

Means for Solving the Problems

[0011] As a result of various studies to solve the above problems, the present inventors have found that by controlling the contents of Fe and Si, the number density of the second-phase particles present on the surface of the aluminum alloy foil, and the KAM value in the aluminum alloy foil, the solubility in the etching solution can be improved and high strength and high elongation can be obtained. That is, the present invention has the following features.

[0012] [1] An aluminum alloy foil, wherein (1) the iron content is 0.5% by mass or more and less than 1.8% by mass, the silicon content is less than 1.5% by mass, and the balance is composed of aluminum and inevitable impurities, (2) in the cross-section of the aluminum alloy foil, the equivalent circle diameter of the intermetallic compound exceeds 0.1 μm and is less than 3.0 μm, and the number thereof is 3.0 × 10 5 pieces / mm 2 or more, and (3) with the surface of the aluminum alloy foil as the observation surface, the KAM (Kernel Average Misorientation) value measured by the EBSD (Electron Backscatter Diffraction) method under the conditions of step size: 0.6 μm, Nearest neighbor: 1st, and Maximum Orientation: 5° is 0.8° or more and less than 1.4°.

[0013] [2] The aluminum alloy foil according to [1], wherein the tensile strength in the rolling direction is 120 N / mm 2 or more, the 0.2% proof stress is 80 N / mm 2 or more, and the elongation in the rolling direction at a thickness of 50 μm is 12.0% or more. [3] An aluminum laminate obtained by laminating at least one or more adherends and the aluminum alloy foil according to [1] or [2].

[0014] [4] A process for obtaining an aluminum alloy ingot by casting a molten aluminum alloy having an iron content of 0.5% by mass or more and less than 1.8% by mass, a silicon content of less than 1.5% by mass, and the balance consisting of aluminum and inevitable impurities at a cooling rate of 100 ° C / second or more, a process for obtaining a cold-rolled foil of an aluminum alloy foil by cold-rolling the ingot, and a process for annealing the cold-rolled foil at a temperature of 400 ° C or less. A method for producing an aluminum alloy foil. [5] The method for producing an aluminum alloy foil according to [4], wherein the casting method is twin-roll continuous casting. [6] The method for producing an aluminum alloy foil according to [4] or [5], which includes an intermediate annealing step and does not include a homogenization heat treatment step and a hot rolling step. [Advantages of the Invention]

[0015] The aluminum alloy foil obtained by this invention has high chemical solubility, so it can improve the workability during the production of an etching circuit, especially a printed wiring board, and can exhibit the characteristics of having strength and elongation that can reduce wire breakage after production. [Brief Description of the Drawings]

[0016]

Figure 1

Figure 2

[0017] Hereinafter, embodiments of the present invention will be described in detail. The aluminum alloy foil according to the present invention is a foil containing a predetermined amount of iron (Fe) and silicon (Si), and the balance contains aluminum (Al) and inevitable impurities.

[0018] [Iron content] The aluminum alloy foil of the present invention contains iron (Fe) in an amount of 0.5% by mass or more and less than 1.8% by mass. When the iron content is less than 0.5% by mass, the intermetallic compound is less, and sufficient chemical solubility cannot be obtained, and the strength after final annealing also tends to be insufficient. On the other hand, when the iron content exceeds 1.8% by mass, the primary crystal during casting becomes an Al-Fe-based compound from Al, which may cause casting defects and a decrease in rollability, and also has an adverse effect on strength and elongation. A more preferable range of the iron content is 0.8% by mass or more and less than 1.6%. When within the above range, an aluminum alloy foil excellent in chemical solubility and strength can be stably manufactured.

[0019] [Silicon content] The aluminum alloy foil of the present invention contains silicon (Si) in an amount of less than 1.5% by mass. The addition of silicon promotes the precipitation of Al-Fe-based and Al-Fe-Si-based compounds. As the silicon content increases, the size of the compound becomes larger and the number thereof also increases. When it is 1.5% by mass or more, the crystallized product becomes coarse, and defects such as centerline segregation are likely to occur during CC casting.

[0020] A preferable range of the silicon content is 0.03% by mass or more and less than 1.3%. When it is less than 1.3%, the aluminum alloy foil can be stably manufactured. Although there is no particular limitation on the lower limit value of silicon, it is preferably 0.03% by mass or more in order to avoid an increase in cost due to the use of high-purity ingots.

[0021] [The balance of the components constituting the aluminum alloy foil according to the present invention] The balance of the components constituting the aluminum alloy foil according to the present invention consists of aluminum and inevitable impurities. These inevitable impurities refer to elements inevitably mixed during the production of the aluminum alloy foil. These inevitable impurities may be included within a range that does not affect the properties of the aluminum alloy foil in the present invention.

[0022] Examples of such inevitable impurities include elements such as manganese (Mn), copper (Cu), magnesium (Mg), chromium (Cr), zinc (Zn), titanium (Ti), vanadium (V), gallium (Ga), nickel (Ni), boron (B), zirconium (Zr), etc. Among these, one or more of them may each be contained at 500 mass ppm or less. Since the aluminum alloy foil of the present invention has the above composition, it does not contain expensive additive elements and can reduce the treatment cost of waste liquid when chemically dissolved.

[0023] [Intermetallic compound] The number of intermetallic compounds per unit area of the aluminum alloy foil having an equivalent circle diameter exceeding 0.1 μm and less than 3.0 μm present in the cross-section is 3.0×10 5 pieces / mm 2 or more. When within the above range, by finely dispersing a large number of intermetallic compounds, high chemical solubility and high strength can be achieved.

[0024] The intermetallic compound here refers to particles having a contrast different from that of the aluminum matrix when observing the cross-section of the aluminum alloy foil with, for example, a scanning electron microscope and photographing with a backscattered electron image (texture image). The intermetallic compound refers to, for example, Al-Fe-based, Al-Fe-Si-based, etc., but is not limited thereto.

[0025] Intermetallic compounds with an equivalent circle diameter of 0.1 μm or less were excluded because they are difficult to detect with a scanning electron microscope. Also, coarse intermetallic compounds with an equivalent circle diameter of 3.0 μm or more cause pinholes during rolling and cause wire breaks, so 0.1×10 5 pieces / mm 2 or less is preferable, and 0 pieces / mm 2 is more preferable. Therefore, within the above range, it is set to less than 3.0 μm.

[0026] A more preferable range of the number of intermetallic compounds per unit area having an equivalent circle diameter exceeding 0.1 μm and less than 3.0 μm is 3.5×10 5 pieces / mm 2 or more and 20×10 5 pieces / mm2 The following. 3.5×10 5 pieces / mm 2 or more, an aluminum alloy foil with better chemical solubility can be provided. 20×10 5 pieces / mm 2 If it exceeds this value, the sensitivity of the etched part may be impaired.

[0027] This intermetallic compound, by having the above amount, serves as a starting point for etching, strengthens the strength of the obtained aluminum alloy foil, and has the function of suppressing recrystallization after final annealing. Therefore, the characteristics of the present invention can be more surely exhibited.

[0028] [KAM value] The KAM value in the present invention means that, taking the aluminum foil surface as the observation surface, for the electron beam irradiation spots arranged at a specified step size (interval of 0.6 μm) by the EBSD (electron backscatter diffraction) method, the crystal orientation difference between adjacent spots is measured for all (Nearest Neighbor = 1st), and the measured values with an orientation difference of less than 5° (Maximum misorientation = 5°) are extracted, and it corresponds to the average value obtained in the measurement field of view.

[0029] This KAM value is correlated with the amount of strain accumulation, and it is presumed that the higher the KAM value, the greater the orientation change due to processing strain within the crystal grains. In the present invention, it has been found that excellent strength and elongation can be obtained by controlling the KAM value within an appropriate range. This KAM value is preferably 0.8° or more and less than 1.4°. When the KAM value is less than 0.8°, it is a state with little strain where recovery and recrystallization have progressed, so sufficient strength tends not to be obtained. When the KAM value is 1.4° or more, it is a state with a large amount of remaining strain, and sufficient elongation tends not to be obtained. A more preferable range of the KAM value is 0.9° or more and less than 1.3°. When within the above range, an aluminum alloy foil with better strength and elongation can be manufactured.

[0030] [Manufacturing method] Next, a method for manufacturing an aluminum alloy foil according to the present invention will be described. The method for manufacturing an aluminum alloy foil according to the present invention includes a step of preparing an aluminum master alloy so as to fall within the above composition range and heating it to produce an aluminum alloy melt, a step of casting the aluminum alloy melt at a cooling rate of 100 °C / second or more to produce an ingot, a step of cold-rolling the ingot into a foil, and a step of performing final annealing (FA) at 400 °C or less, preferably about 200 to 400 °C.

[0031] More specifically, first, an aluminum ingot, various additive metal elements, or an aluminum master alloy containing them is prepared so as to fall within the above composition range, and heated at 680 to 1000 °C to obtain an aluminum alloy melt. Next, the melt is cast to produce an ingot. This casting preferably uses continuous casting (CC (Continuous casting) casting) that can achieve a high casting cooling rate of 100 °C / second or more, for example, about 300 °C / second. For the aluminum alloy foil of the present invention, it is important to finely disperse the contained intermetallic compounds, which is difficult with semi-continuous casting (DC (Direct Chill) casting) with a casting cooling rate of about 10 °C / second.

[0032] The CC cast plate is obtained with a thickness of about 7 mm and cold-rolled into a foil with a predetermined thickness. It is also possible to perform intermediate annealing (IA) during the cold-rolling process to facilitate rolling or control the solid solution and precipitation state. Finally, FA is performed at 400 °C or less, preferably about 200 to 400 °C to obtain an aluminum alloy foil.

[0033] [Cooling rate] In the method for manufacturing an aluminum alloy foil according to the present invention, the cooling rate during casting is 100 °C / second or more. By setting it within the above range, since intermetallic compounds can be finely dispersed in the aluminum matrix phase, recrystallization during FA can be suppressed. Therefore, the strength and elongation of the aluminum alloy foil can be improved. In addition, since intermetallic compounds serving as the starting point of chemical dissolution can be finely dispersed, the etching rate can be improved when used for a wiring board.

[0034] The cooling rate is preferably 200 °C / second or more, and more preferably 300 °C / second or more. When within the above range, the above-described effects can be further improved. On the other hand, the upper limit of the cooling rate during casting is not particularly limited, but from the viewpoint of the apparatus, 1000 °C / second or less is sufficient.

[0035] The casting method for achieving the above cooling rate is not particularly limited, but examples include continuous casting (CC casting), particularly twin-roll continuous casting. The casting thickness is not particularly limited, but for example, it is 3 mm or more and 10 mm or less, and more preferably more than 3 mm and 8 mm or less. When within the above range, a desired cooling rate can be obtained even inside the ingot.

[0036] [Homogenization heat treatment] In the method for manufacturing an aluminum alloy foil according to the present invention, it is preferable not to include a homogenization heat treatment step. When performing a homogenization heat treatment step, added elements supersaturated solid-solved by a casting process having a high cooling rate precipitate, leading to coarsening of the structure, and there is a possibility that it becomes difficult to exhibit the characteristics of this invention, which has sufficient high strength, elongation, and chemical solubility.

[0037] [Hot rolling] In the method for manufacturing an aluminum alloy foil according to the present invention, it is preferable not to include a hot rolling step. When performing a hot rolling step, added elements supersaturated solid-solved by a casting process having a high cooling rate precipitate, leading to coarsening of the structure, and there is a possibility that it becomes difficult to exhibit the characteristics of this invention, which has sufficient high strength, elongation, and chemical solubility.

[0038] [Intermediate annealing (IA)] In the method for manufacturing an aluminum alloy foil according to the present invention, it is preferable to include an intermediate annealing step. The intermediate annealing step may or may not be present, but for the purpose of improving rollability, it is preferably carried out within a range that does not affect the properties of the aluminum alloy foil. As an example, it is carried out at a temperature of 250°C or higher and 550°C or lower in an air atmosphere for 1 hour or longer and 20 hours or shorter.

[0039] [Final annealing (FA)] In the method for manufacturing an aluminum alloy foil according to the present invention, a final annealing step is included. The final annealing step is carried out, for example, at 400°C or lower in an air atmosphere or an inert gas atmosphere. When the final annealing temperature is less than 200°C, the removal of rolling oil is insufficient, and the KAM value often becomes larger than 1.4°. When the final annealing temperature exceeds 400°C, there is concern about deterioration of chemical solubility due to coarsening of the structure, and the KAM value often becomes smaller than 0.8°. The final annealing is preferably at 200°C or higher and 400°C or lower, more preferably at 275°C or higher and 400°C or lower, for 1 hour or longer and 60 hours or shorter. When these conditions are satisfied, the obtained aluminum alloy foil has sufficient removal of rolling oil, can be controlled within the above-mentioned KAM value range, and sufficient strength and elongation can be obtained.

[0040] [Properties of Aluminum Alloy Foil] <Strength, 0.2% proof stress, elongation> The aluminum alloy foil according to the present invention has a tensile strength in the rolling direction of 120 N / mm 2 or more, preferably, a 0.2% proof stress of 80 N / mm 2 or more, and preferably an elongation in the rolling direction at a thickness of 50 μm of 12.0% or more. When the tensile strength and 0.2% proof stress are within the above ranges, sufficient workability can be ensured in the manufacturing process of the printed wiring board. Incidentally, when simply described as "proof stress" in this specification, it refers to "0.2% proof stress".

[0041] [Thickness] The thickness of the aluminum alloy foil is not particularly limited, but is preferably 7 μm or more and less than 100 μm. More preferably, it is 9 μm or more and 50 μm or less. If it is within the above range, it can be suitably adopted for printed wiring boards. If it is less than 7 μm, the workability in the manufacturing process of the printed wiring board tends to deteriorate. If it is 100 μm or more, the dissolution time during etching becomes long and it tends to be unsuitable for printed wiring boards.

[0042] [Aluminum laminate] The aluminum alloy foil according to the present invention can be made into an aluminum laminate by laminating at least one or more adherends on at least one surface thereof. The above adherend may or may not have flexibility. For example, resin films such as polyethylene, polypropylene, polyester, polycarbonate, polyimide, polyamide, or paper phenolic resin plates, glass epoxy plates, etc. are preferably used.

[0043] The method of laminating the aluminum alloy foil and the adherend is not particularly limited, and examples include lamination with an adhesive. Also, before the above lamination, the surface of the aluminum alloy foil may be roughened, washed, coated, etc.

[0044] [Printed wiring board] A resist ink is printed in a pattern on the surface of the aluminum foil of the laminate so as to have a desired wiring shape, and then immersed in an etching solution to dissolve the portion where the resist ink is not printed. After that, the resist is peeled off as necessary, whereby an aluminum foil can be formed into a wiring pattern to obtain a printed wiring board. Known printing methods can be used, such as gravure printing and screen printing.

[0045] As the above resist ink, known ones can be used, and organic or inorganic resists, etc. can be appropriately adopted depending on the workability on the etching solution and the aluminum surface. As the above-mentioned etching solution, known ones can be used, and acidic, alkaline, etc. can be adopted as appropriate. For example, an aqueous solution of sodium hydroxide (caustic soda), hydrochloric acid, ferric chloride solution, copper chloride solution, hydrogen peroxide, etc., or a mixed solution thereof can be mentioned.

Examples

[0046] Hereinafter, examples and comparative examples will be given to clarify the content of the present invention more clearly. First, the test method used in this example is shown below.

[0047] (Test method) [Number of intermetallic compounds] After the cross-section of the aluminum alloy foil was smoothed by a cross-section polisher (SM-09010 manufactured by JEOL Ltd.), it was observed at a magnification of 2500 times with an electrolytic release type scanning electron microscope (JSM-7200F manufactured by JEOL Ltd.). In order to make the intermetallic compounds easier to observe, it was photographed with a backscattered electron image (composite image). The size and number of intermetallic compounds were evaluated using image analysis and measurement software WinROOF2018 (Mitani Shoji Co., Ltd.: Version 4.7.5). The contrast and brightness were adjusted by image processing in the analysis software to clarify the intermetallic compounds. Then, binarization was performed with a single threshold value so that only the data of the intermetallic compound part of the cross-section of the aluminum alloy foil could be extracted. Data processing was performed to delete the part with an equivalent circle diameter of 0.1 μm or less in the binarized intermetallic compound part, and the number of those with an equivalent circle diameter of less than 3.0 μm and the number of those with an equivalent circle diameter of 3.0 μm or more were measured in the remaining part with an equivalent circle diameter exceeding 0.1 μm, and the number of intermetallic compounds per unit area was calculated. Five fields of view were randomly photographed, and the average value was obtained.

[0048] [KAM value] The KAM value on the surface of the aluminum alloy foil was calculated by using an electrolytic emission scanning electron microscope (JSM-7200F manufactured by JEOL Ltd.) equipped with an EBSD analyzer (Verocity manufactured by TSL Solutions Co., Ltd.) at a magnification of 300 times, with a step size of 0.6 μm in a field of view of 300 μm × 300 μm. From the measurement results, it was calculated by the analysis software OIM Analysis 8 (manufactured by TSL Solutions Co., Ltd.) with Nearest Neighbor = 1st and Maximum misorientation = 5°. As a pretreatment, the surface of the aluminum alloy foil was mirror-finished by electrolytic polishing. Measurements were taken in 3 randomly selected fields of view, and the average value was obtained.

[0049] [Tensile Test] The aluminum alloy foil after FA was cut into strip test pieces with a width of 15 mm and a length of 200 mm, and a tensile test was performed using a Strograph VES5D manufactured by Toyo Seiki Seisaku-sho, Ltd. The distance between the chucks was 100 mm, the tensile speed was 10 mm / min, and data on tensile strength, yield strength, and elongation were obtained. The test was carried out 3 times, and the average value was calculated. The direction of the tensile test was aligned with the rolling direction.

[0050] [Dissolution Time] Masking tape was attached so that only one side surface of the aluminum alloy foil was exposed at 1 × 1 cm, and it was impregnated in an etching solution at 40 °C prepared to contain 8 mass% hydrochloric acid and 4 mass% aluminum chloride, and the time until the exposed part of the aluminum alloy foil was completely dissolved was measured.

[0051] (Examples 1 - 8, Comparative Examples 1 - 4) Aluminum alloys with the respective compositions shown in Tables 1 and 2 below were melted, and after degassing and inclusion removal treatment of the molten metal, a casting plate with a thickness of 7 mm was obtained by CC casting. Cold rolling was performed on the obtained casting plate to a thickness of 1 mm, and then intermediate annealing was carried out at the temperatures described in Tables 1 and 2. After intermediate annealing, further cold rolling was performed to obtain a cold-rolled foil with a thickness of 50 μm. The obtained cold-rolled foil was subjected to final annealing at the temperatures described in Tables 1 and 2 for 2 hours. The final thickness was as described in Tables 1 and 2. Each physical property of the obtained aluminum alloy foil was measured by the methods described above. The results are shown in Tables 1 and 2.

[0052] (Comparative Examples 5 to 9) Ingots were obtained by DC casting with the compositions described in Table 2 below. After machining the surfaces of the ingots, homogenization heat treatment was performed at the temperatures described in Table 2, and then hot rolling was carried out to obtain a plate with a thickness of 7 mm. Thereafter, cold rolling, intermediate annealing, and final annealing were carried out under the conditions described in Table 2 in the same manner as in the above Examples. The final thickness shall be as described in Table 2. Each physical property, etc. of the obtained aluminum alloy foil was measured by the method described above. The results are shown in Table 2.

[0053] In addition, the micrographs taken during the measurement of the number of intermetallic compounds in Example 1 and Comparative Example 7 are shown in Fig. 1 (Example 1) and Fig. 2 (Comparative Example 7). From these results, it is clear that in Example 1, a large number of fine intermetallic compounds of 0.1 μm to 3.0 μm are present. On the other hand, in Comparative Example 7, it is clear that there are few fine intermetallic compounds of 0.1 μm to 3.0 μm.

[0054]

Table 1

[0055]

Table 2

Claims

1. An aluminum alloy foil, comprising: (1) an iron content of 0.5% by mass or more and less than 1.8% by mass, a silicon content of less than 1.5% by mass, and the balance consisting of aluminum and inevitable impurities; (2) The cross-section of the aluminum alloy foil contains 3.0×10 ５ particles / mm ２ or more of intermetallic compounds having an equivalent circle diameter exceeding 0.1 μm and less than 3.0 μm, (3) with the surface of the aluminum alloy foil as the observation surface, the KAM (Kernel Average Misorientation) value measured by the EBSD (Electron Backscatter Diffraction) method under the conditions of step size: 0.6 μm, Nearest neighbor: 1st, Maximum Orientation: 5° is 0.8° or more and less than 1.4°; (4) a tensile strength in the rolling direction of 120 N / mm2 or more and a 0.2% proof stress of 80 N / mm2 or more; An aluminum alloy foil having an elongation in the rolling direction at a thickness of 50 μm of 12.0% or more.

2. An aluminum laminate formed by laminating at least one layer or more of an adherend and the aluminum alloy foil according to Claim 1.

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