JPH11328939A - Copper alloy strip for hard disk drive case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the reduction of nose at the time of operation and to improve discoloration resistance by coating at least one surface of a copper alloy plate with Ni or Ni alloy layers. SOLUTION: Both surfaces of the copper alloy plate are coated with the Ni or Ni alloy layers and the thickness of the Ni or Ni alloy layers is specified to 0.5 to 1.5 μm. The copper alloy plate consists of a Cu-Zn alloy contg. 5 to 42 wt.% Zn and consisting of the balance Cu and inevitable impurities and has a high noise reducing effect and excellent corrosion resistance. The copper alloy plate formed by incorporating Ni into the Cu-Zn alloy consists of the compsn. of 7 to 26% Ni and 5 to 30% Zn and is distinguished in the noise reducing effect and corrosion resistance. Sn is preferably incorporated at 0.1 to 3% into the alloy for the degraded stress corrosion crack sensitivity. The total of Pb, Fe, P, Mn, Mg, Ti, Ca, Bi, Co, Ag, Zr, Cr, rare earth elements, impurity elements, etc., in the Cu-Zn alloy, Cu-Zn-Ni alloy and Cu-Zn-Ni-Sn alloy may be preferably suppressed to <=2%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy strip for a hard disk drive case, which can reduce noise during operation of the hard disk drive and is excellent in discoloration resistance.

[0002]

2. Description of the Related Art Aluminum alloy plates which are lightweight and excellent in press formability are frequently used in hard disk drive cases for hard disks and floppy disks used for memories of word processors, personal computers, work stations and the like.

[0003]

However, especially in a large hard disk drive, there is a problem that vibration accompanying the rotation of the hard disk is amplified in the case body and generates annoying noise. An object of the present invention is to provide a copper alloy strip for a hard disk drive case that can reduce noise during operation of the hard disk drive and is excellent in discoloration resistance.

[0004]

According to the first aspect of the present invention,
This is a copper alloy strip for a hard disk drive case in which at least one surface of a copper alloy plate is coated with a Ni or Ni alloy layer.

According to a second aspect of the present invention, there is provided the copper alloy strip for a hard disk drive case according to the first aspect, wherein the thickness of the Ni or Ni alloy layer is 0.5 to 1.5 μm.

According to a third aspect of the present invention, the copper alloy plate contains 5 to 42% by weight of Zn (hereinafter abbreviated as%), and the balance consists of Cu and unavoidable impurities.
Or a copper alloy strip for a hard disk drive case according to 2.

According to a fourth aspect of the present invention, the copper alloy plate contains 5 to 42% of Zn and 0.1 to 3% of Sn, with the balance being Cu and unavoidable impurities. 2. A copper alloy strip for a hard disk drive case according to 2.

According to a fifth aspect of the present invention, the copper alloy plate contains 7 to 26% of Ni and 5 to 30% of Zn, with the balance being Cu and unavoidable impurities.
It is a copper alloy strip for a hard disk drive case described.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The copper alloy strip of the present invention can reduce noise during operation of a hard disk drive. In the present invention, any copper alloy can be used for the copper alloy plate, including pure copper. Among the above copper alloys, a copper alloy containing 5 to 42% of Zn is preferable because it has a large noise reduction effect and also has excellent press formability and corrosion resistance. The noise reduction effect is remarkably exhibited when the Zn content is 30 to 42%. The Cu-Z
It is desirable to include Sn in the n-alloy because the sensitivity to stress corrosion cracking is reduced. If the content is less than 0.1%, the effect cannot be sufficiently obtained, and if it exceeds 3%, the workability of the copper alloy deteriorates, so that 0.1 to 3% is desirable.

[0010] A copper alloy containing Ni in a Cu-Zn alloy has a large noise reduction effect and excellent corrosion resistance.
The punched end face is also difficult to discolor. The effect is Ni7-26
% And a composition of 5 to 30% of Zn. Also in the case of this alloy, it is desirable to contain 0.1 to 3% of Sn because the sensitivity to stress corrosion cracking decreases.

In the Cu-Zn alloy, Cu-Zn-Sn alloy, Cu-Zn-Ni alloy and Cu-Zn-Ni-Sn alloy, Pb, Fe, P, Mn, Mg, Ti, C
Alloying elements such as a, Bi, Co, Ag, Zr, Cr, and rare earth elements or impurity elements are not more than 2% in total and may be contained as long as they do not significantly impair the properties intended by the present invention. Absent.

In the present invention, since the Ni or Ni alloy layer is unlikely to give a fingerprint, discoloration due to the attachment of the fingerprint to the hard disk drive case is prevented. Ni or N
The i-alloy layer also improves the dezincification corrosion of the copper alloy strip. The Ni or Ni alloy layer 2 is usually coated on both surfaces of the copper alloy plate 1 as shown in FIG. In the case of double-sided coating, it is particularly preferable to thickly coat the surface where corrosion resistance is required. Further, as shown in FIG. 1B, the copper alloy plate 1 may be coated only on the surface where corrosion resistance is required. In FIGS. 1A and 1B, reference numeral 3 denotes a copper alloy strip of the present invention.

In the present invention, if the thickness of the Ni or Ni alloy layer is 0.5 μm or less, the effect cannot be sufficiently obtained, and if it exceeds 1.5 μm, the effect is saturated and the press formability deteriorates. Become like Therefore, Ni or Ni
The thickness of the alloy layer is desirably 0.5 to 1.5 μm. The Ni or Ni alloy layer can be easily coated to an appropriate thickness by a normal method such as an electroplating method.

The copper alloy strip of the present invention is used, for example, as shown in FIG. 2, by bonding it to an upper surface of a lid 5 of a hard disk drive case 4 made of an all-aluminum alloy as a vibration absorbing plate 8 with an adhesive 6. In the figure, reference numeral 7 denotes a case body. Further, since the copper alloy strip of the present invention is heavy, it is preferable to use it for a part of an aluminum alloy hard disk drive case so as not to hinder the weight reduction. As a place to be used, a lid 5 that easily vibrates can be used.

[0015]

The present invention will be described below in detail with reference to examples. One or both sides of a copper plate or a copper alloy plate having a thickness of 0.8 mm were electroplated with a Ni or Ni alloy layer to a thickness of 0.5 or 1.5 μm, respectively, and pressed into a lid of a hard disk drive case. The press forming of the lid was performed such that the side covered with the Ni or Ni alloy layer or the side covered thickly was on the outside of the lid. Press molding was successfully performed.

Each of the thus obtained lids was attached to an aluminum alloy case main body, and further, parts were set to produce a hard disk drive case, and its discoloration resistance and noise during operation were investigated. . For comparison, a similar investigation was conducted for a conventional all-aluminum alloy hard disk drive case. The discoloration resistance was evaluated on a five-point scale by visually observing the degree of discoloration after placing a fingerprint on the outer surface of the lid of the hard disk drive case and allowing it to stand at room temperature for 10 days (A: extremely little discoloration to E: severe discoloration). The magnitude of the noise was evaluated by a person on a scale of 5 by hearing the noise emitted from the drive during driving (A: the noise was very low to E:
The noise is terrible). If both the colorfastness and the noise are C or more, there is no practical problem. The results are shown in Tables 1 and 2.

[0017]

[Table 1]

[0018]

[Table 2] (Note) * indicates a conventional product.

As is clear from Tables 1 and 2,
Nos. 1 to 15 are all superior in discoloration resistance and noise are smaller than the conventional No. 16. In particular, in Nos. 5 to 10,15, the noise was extremely low because the copper alloy plate contained 30% or more of Zn. Those coated with a Ni or Ni alloy layer of 0.5 μm or more were particularly excellent in discoloration resistance. Further, a separate experiment was performed, and it was confirmed that the example of the present invention was also excellent in dezincification corrosion resistance.

(Embodiment 2) The copper alloy strip 3 of the present invention obtained in Embodiment 1 is used as a vibration absorbing plate 8 shown in FIG. 2 as the upper surface of a lid 5 of a conventional hard disk drive case 4 made of an all-aluminum alloy. A similar investigation was performed on the substrate joined with the adhesive 6, and excellent discoloration resistance and low noise were obtained as in Example 1.

[0021]

As described above, the hard disk drive using the copper alloy strip of the present invention for the case has less noise due to vibration during operation than the conventional hard disk drive made of aluminum alloy case. This noise reduction effect becomes more remarkable in the copper alloy strip containing Zn. Since the copper alloy strip is coated with a Ni or Ni alloy layer, fingerprints are less likely to be formed, the discoloration resistance is excellent, and the dezincification corrosion resistance is also improved.
In addition, even if it is used locally for the lid part of the aluminum alloy case, it is effective and does not impair the weight reduction. Therefore, an industrially remarkable effect is achieved.

[Brief description of the drawings]

FIGS. 1A and 1B are longitudinal sectional views showing first and second examples of the copper alloy strip of the present invention.

FIG. 2 is a longitudinal sectional view showing an example of a hard disk drive case using the copper alloy strip of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 copper alloy plate 2 Ni or Ni alloy layer 3 copper alloy strip of the present invention 4 hard disk drive case using copper alloy strip of the present invention 5 lid 6 adhesive 7 case body 8 vibration absorbing plate

Claims (5)

[Claims] 1. A copper alloy strip for a hard disk drive case in which at least one surface of a copper alloy plate is coated with Ni or a Ni alloy layer. 2. The Ni or Ni alloy layer has a thickness of 0.5 to 0.5.
The copper alloy strip for a hard disk drive case according to claim 1, wherein the thickness is 1.5 μm. 3. The hard disk drive case according to claim 1, wherein the copper alloy plate contains 5 to 42% by weight of Zn (hereinafter abbreviated as%) and the balance consists of Cu and unavoidable impurities. For copper alloy strips. 4. The hard disk drive case according to claim 1, wherein the copper alloy plate contains 5 to 42% of Zn and 0.1 to 3% of Sn, with the balance being Cu and unavoidable impurities. For copper alloy strips. 5. The copper alloy sheet contains 7 to 26% of Ni and 5% of Zn.
3. The copper alloy strip for a hard disk drive case according to claim 1, wherein the copper alloy strip contains about 30% and the balance consists of Cu and inevitable impurities. 4.