JPS63250112A - Aluminum alloy foil for cathode of electrolytic capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an aluminum alloy foil for electrolytic capacitor cathodes.

Conventional technology and its problems In order to increase the capacitance 1 (C) of an electrolytic capacitor,
It is necessary to increase not only the capacitance 1 (CA) of the wA pole part but also the capacitance (Co) of the cathode part.

Conventionally, in order to increase the capacitance of the cathode part, aluminum alloy foil has been used, for example, which is made by adding 0.1 to 0.5% of copper to aluminum with a purity of 99.3 to 99.8%. (Special Publication No. 44-25016). However, with rapid technological advances in various fields that use electrolytic capacitors, further improvements in the capacitance of the cathode portion of electrolytic capacitors are desired.

Means for Solving the Problems In view of the current state of the technology as described above, the inventor of the present invention, as a result of intensive research, has developed a method of incorporating nickel at a specific level into aluminum and keeping the titanium content below a certain value. It has been found that when etching is performed, the potential difference between the aluminum matrix and the precipitates in the matrix is increased, and as a result, the capacitance of the aluminum foil after etching is significantly increased.

That is, the present invention provides the following aluminum alloy.

■An aluminum alloy foil for an electrolytic capacitor cathode containing 0.01 to 0.1% by weight of nickel and a titanium content of 0.0011% by weight or less.

When nickel is added to aluminum, A12-N
The amount of +-Fe compound precipitated increases. This AQ-N
Since the potential of the 1-Fe compound is quite noble relative to aluminum, the potential difference between the compound and the aluminum matrix increases.

Therefore, when such an aluminum alloy foil is subjected to etching, it is possible to preferentially generate a large number of fine pits in the aluminum matrix.
An improvement in capacitance is achieved.

In the present invention, the nickel content is 0.01 to 0.0.
1E1iffi% (hereinafter simply referred to as %). If the nickel content is less than 0.01%, AQ-N +
The amount of -Fe compound precipitated decreases, and almost no increase in capacitance is observed.

On the other hand, if the nickel content exceeds 0.1%,
The melting of the entire aluminum foil progresses, resulting in insufficient bit formation.

Further, in the present invention, it is essential to suppress the content of titanium as an impurity to 0.001% or less. When the titanium content exceeds o, ooi%, the dissolution of the aluminum foil surface becomes severe, and it becomes impossible to form fine bits on the aluminum foil surface, resulting in a decrease in capacitance and an increase in etchants. Blackening of the foil surface becomes intense.

The titanium content can be easily suppressed, for example, by adding boron to molten aluminum and separating the produced TiB2 by sedimentation.

The aluminum foil of the present invention may contain unavoidable impurities such as Fe and Si.

Effects of the Invention According to the present invention, the capacitance of an aluminum foil for an electrolytic capacitor cathode can be significantly improved without substantially reducing other properties such as strength.

EXAMPLES Examples will be shown below to further clarify the characteristics of the present invention.

Example 1 Titanium content less than mioppm, Earlumilum purity 99
．． An 8% primary electrolytic aluminum ingot was melted and aluminum alloy slabs were cast with or without the addition of a predetermined amount of nickel.

These slabs were subjected to a normal foil manufacturing process to a thickness of 50 μm.
After obtaining the alloy foil of m, it was annealed at 400° C. for 5 hours under vacuum. Table 1 shows the content (%) of components other than aluminum in the alloy foil thus obtained.

Table 1 Sample　　Ni　　Fe　　　T1No.

IO,010,060,0005 20,030,060,0005 30,100,06,0,0005 40,300,060,0005 500,060,0005 The obtained soft foil was treated with FA acid 15% by volume and phosphorus. acid 2% by volume
Etching was performed for 20 to 120 seconds at a bath temperature of 60 DEG C. and an alternating current density of 0.5 A/ri. Next, add 25 pieces of etched foil.
Chemical conversion was carried out at 3V using 5% boric acid at 0.degree. C., and the capacitance was measured. The results are shown in Figure 1.

As is clear from FIG. 1, the aluminum alloy foil of the present invention (
In Nos. 1 to 3), by adding manganese, a significant improvement in capacitance was achieved, and the rise in capacitance relative to the melting region R was also faster. This shows that a higher capacitance value can be obtained compared to the comparative aluminum foil (No. 5) even with the same melt loss.

Example 2 The composition shown in Table 2 (
%) soft aluminum foil was obtained.

The capacitance measured in the same manner as in Example 1 is shown in FIG.

It is clear that when the titanium content exceeds 0.001%, the capacitance after etching is reduced.

Table 2 Sample　　Ni　　Fe　　　T1No.

10.03 0.06 0.0005 2 0.03 0.06 0.00103 0.03
0.06 0.00204 0.03 0.06 0.
It is clear that when the 0100 titanium content exceeds 0.001%, it also reduces the capacitance after etching.

[Brief explanation of drawings]

Figure 1 is a graph showing the influence of nickel content on melt loss and capacitance of aluminum alloy foil, Figure 2 is
Graphs showing the influence of titanium as an impurity on the dissolution loss and capacitance ω of the ΔQ-xi alloy foil are shown. (That's all) Figure 1 Dew! Amount of gourd (mg/locm2) Figure 2

Claims (1)

[Claims] [1] Aluminum alloy foil for an electrolytic capacitor cathode containing 0.01 to 0.1% by weight of nickel and having a titanium content of 0.001% by weight or less.