JPS6059982B2 - Method for manufacturing aluminum foil for electrolytic capacitor electrodes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing aluminum foil for electrolytic capacitor electrodes.

The condition that aluminum foil for electrolytic capacitor electrodes must have is a large capacitance, but in the recrystallized texture of the final annealed aluminum foil, the (100) plane is parallel to the surface of the foil, and the [001) orientation is It is a well-known fact that if there are many so-called cubic crystals in which the aluminum foil is parallel to the rolling direction, the capacitance will increase when this aluminum foil is etched.

Various methods of manufacturing aluminum foil for electrolytic capacitor electrodes have been proposed using the above facts. However, with the conventional method, it has not been possible to obtain an aluminum foil with a sufficiently large capacitance in which the recrystallized texture after final sintering has too many cubic orientation crystals. This invention was made in view of the above circumstances, and compared to the conventional method, there are many cubic orientation crystals in the recrystallized texture after final sintering, and therefore, the capacitance is large. An object of the present invention is to provide a method for manufacturing aluminum foil.

The method for manufacturing aluminum foil for electrolytic capacitor electrodes according to the present invention includes the steps of holding an aluminum material at a temperature range of 350 to 520°C for 1 to 15 hours to precipitate solute atoms in the aluminum material, and aluminum from which the solute atoms have precipitated. A process of rolling the material at a reduction rate of 60% or more, a process of intermediate annealing the rolled aluminum material at a temperature range of 200 to 3800C for 0.5 to 150 hours, and a process of intermediately annealing the aluminum material by 5 to 70%. This method is characterized by comprising a step of cold rolling the aluminum foil to a predetermined thickness at a rolling reduction ratio of 1, and a final annealing step of the aluminum foil at a temperature range of 350 to 640°C. In the above, the aluminum material has a purity of 99.8 to 99.
It is preferable to use a material having a content of 999 wt % and containing very small amounts of Fe, Si, etc.

Further, the aluminum material is a continuous cast plate made by a continuous casting and rolling method, a slab obtained by a normal manufacturing method, or a slab obtained by hot rolling. When the aluminum material is held at a temperature range of 350 to 520°C for 1 to 1 hour to precipitate solute atoms such as Fe and Si in the aluminum material, it becomes difficult to heat the material during intermediate and final sintering, especially in the final sintering. , many recrystallized grains with cubic orientation occur.

Heating holding temperature and time are 360 to 520°C, respectively.
, the reason why it is limited to the range of 1 to 150 hours is that below the above lower limit values, solute atoms such as Fe and Si will not precipitate, and on the other hand, when the upper limit values are exceeded, solid solution of solute atoms will progress and they will precipitate uniformly. This is because the number of recrystallized grains with cubic orientation that occurs during intermediate sintering decreases. The above temperatures and times are in particular 400-480'C and 5-480'C, respectively.
It is preferable that it is in the range between 2@. When an aluminum material in which solute atoms have precipitated is rolled at a reduction ratio of 60% or more, many recrystallized grains with cubic orientation occur during intermediate sintering.

The above-mentioned rolling is performed only in the cold, or hot and then cold. The reason for setting the rolling reduction ratio to be 60% or more is because if the rolling reduction ratio is less than 60%, recrystallized grains with a cubic orientation will not be generated during intermediate sintering, but it is particularly preferable to set the rolling reduction ratio to be 80% or more. Aluminum material rolled with a rolling reduction of 60% or more is heated to zero in a temperature range of 200 to 380°C.
．． When intermediate sintering is performed between 5 and 15 (Fi'), recrystallized grains with cubic orientation occur in the aluminum material.

The temperature and time of intermediate sintering are 200 to 380, respectively.
The reason why it is limited to the range between 0.5 and 15 degrees Celsius is that below the above lower limit values, recrystallized grains with cubic orientation are difficult to form in the aluminum material, and when the upper limit values are exceeded, recrystallization grains with other orientations occur. This is because grains are also generated, and in the final sintering, recrystallized grains with a cubic orientation are prevented from continuously generating around the recrystallized grains with a cubic orientation generated in the intermediate sintering. The above temperature and time are, respectively, particularly between 230 and 3
50°C and 1 to 2 temples are preferable. When intermediate-sintered aluminum material is cold-rolled at a rolling reduction ratio of 5 to 70%, in the resulting aluminum foil, rolling strain occurs in cubic-oriented recrystallized grains generated during intermediate-sintering and other crystal grains. is added. In this case, strain is imparted to recrystallized grains with a cubic orientation, and the number of recrystallized grains with a cubic orientation dramatically increases in the final sintering. The above rolling reduction rate is 5-70%
The reason for this is that if it is less than the lower limit above, it will not be possible to give strain to recrystallized grains with a cubic orientation generated during intermediate sintering, and if it exceeds the upper limit, the recrystallized grains with a cubic orientation generated during intermediate sintering will not be strained. A shift occurs in the orientation of the crystal grains, and as a result, the recrystallized grains with the cubic orientation decrease, and during the final sintering, recrystallized grains with the cubic orientation must be generated again. At this time, the recrystallized grains with the other orientation must be generated. This is because grains are also generated at the same time, so the number of recrystallized grains with cubic orientation does not increase. When the aluminum foil obtained by cold rolling is finally sintered in a temperature range of 350 to 640°C, recrystallized grains with cubic orientation are generated around the recrystallized grains with cubic orientation generated during intermediate sintering. This effect cannot be obtained outside the above temperature range. The aluminum foil that has been finally sintered as described above has an extremely large number of cube-oriented crystals in its recrystallized texture, so when this aluminum foil is etched, its capacitance becomes extremely large.

Next, examples and comparative examples of the present invention will be shown.

First, eight types of samples A to H shown below were prepared. Sample A: Aluminum material with purity of 99.992wt% heated to 400℃
The aluminum material was held for 2 hours to precipitate solute atoms, then hot rolled to a thickness of 7 TWL, and then cold rolled to 0.
．． The foil was rolled to a thickness of 12wn.

Next, 2 pieces of aluminum foil rolled to 0.12mm
After intermediate sintering at 500C for 10 hours, 0.1W$ in cold
It was rolled to a thickness of t. Finally, add 5 pieces of this aluminum foil.
Final sintering was carried out at 50°C for 1 hour. Sample B Compared to the above sample A, the sample was obtained under all the same conditions as sample A, except that the thickness of the cold rolled finish was set to 0.15 Tf$L immediately before intermediate sintering. .

Sample C Compared to sample A above, the thickness after cold rolling is 0.30T just before intermediate sintering! U! A sample was obtained under the same conditions as in Sample A except that the temperature was changed to t.

Sample D: An aluminum material with a purity of 99.98 Wt% is held at 450°C for 10 hours to precipitate solute atoms, and this aluminum material is heated to 7Tn! The foil was rolled to a thickness of n and further cold rolled to a thickness of 0.15 m.

Next, the aluminum foil rolled to 0.15 mm was rolled to 23 mm.
After intermediate sintering at 0° C. for 48 hours, it was cold rolled to a thickness of 0.17 m. Finally, heat this aluminum foil to 550°C.
The final sintering was carried out for 1 hour. Sample E Compared to Sample D above, a sample was obtained under the same conditions as Sample D except that the intermediate sintering conditions were changed to 300° C. for 1 full hour.

Sample F Compared to Sample D above, a sample was obtained under all the same conditions as Sample D, except that the intermediate sintering conditions were changed to 350° C. for 4 hours.

Sample G An aluminum material with a purity of 99.992 Wt% was heated to 7
The foil was then rolled to a thickness of 0.12wn and further cold rolled to a thickness of 0.12wn.

Then, after intermediate sintering of this foil at 250°C for 10 hours,
0.17077 in cold! Rolled to a thickness of . Finally, this aluminum foil was finally sintered at 550° C. for 1 hour. Sample H An aluminum material with a purity of 99.993 Wt% was heated to
The foil was rolled to a certain thickness, and then cold rolled to a thickness of 0.1 Trrm.

Finally, this aluminum foil was final sintered at 550° C. for 1 hour. Using the above samples A-H, Cu target, N
Diffraction intensity 1200 of the (200) plane of each sample was measured with 30Kv120rr1A X-ray using an i filter.

Claims (1)

[Claims] 1 Aluminum material at a temperature range of 350 to 520℃
A step of holding the aluminum material for ~150 hours to precipitate the solute atoms in the aluminum material, a step of rolling the aluminum material from which the solute atoms have precipitated at a reduction ratio of 60% or more, and a step of rolling the rolled aluminum material at a temperature of 200 to 380°C. Range 0.5-1
A step of intermediate annealing for 50 hours, a step of cold rolling the intermediate annealed aluminum material at a reduction rate of 5 to 70% to form an aluminum foil of a predetermined thickness, and a step of rolling this aluminum foil to a predetermined thickness for 35 hours.
A method for manufacturing an aluminum foil for electrolytic capacitor electrodes, which comprises a final annealing step in a temperature range of 0 to 640°C.