JP2633606B2 - Method for forming conductive film on aluminum or aluminum alloy member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A method for forming a conductive film of aluminum or an aluminum alloy, which forms a conductive film extending from an aluminum base material through an aluminum oxide layer to the surface, relates to a method for forming a conductive film by efficiently performing a plating process. For the purpose of improving the yield, after removing the barrier layer at the bottom of the minute hole of the aluminum oxide layer formed on the aluminum substrate, immerse it in a plating bath to which a smoothing agent, brightener and activator have been added. By controlling the current density and the plating time, a bright nickel plating layer that spreads flat on the aluminum oxide surface from the minute holes and the barrier layer removed portion from the aluminum substrate.

[Field of Industrial Application] The present invention relates to a method for forming a conductive coating on an aluminum or aluminum alloy member, which forms a conductive coating extending from an aluminum substrate through an aluminum oxide layer to the surface.

In order to reduce the weight of the information device housing and improve corrosion resistance, the housing is made of aluminum or aluminum alloy.

In the case of aluminum housing for such information equipment, an aluminum oxide layer (alumite layer) is formed on the surface of the aluminum case by an alumite treatment method to secure hardness and corrosion resistance, and furthermore, the contact point of the earth contact of the housing is formed. For this purpose, a nickel conductive film is formed from the aluminum base through the aluminum oxide layer to the surface at the contact formation position.

[Prior Art] Conventionally, as a method of forming a conductive film for ground contact on the surface of an aluminum case having an aluminum oxide film, for example, those shown in FIGS. 3 and 4 are known.

In this conventional method, first, as shown in FIG.
An aluminum oxide layer 12 is formed on the surface of an aluminum substrate 10 made of aluminum or an aluminum alloy by an alumite treatment method. As is well known, the aluminum oxide layer 12 includes a barrier layer 16 on the aluminum substrate 10 side and a porous layer 18 having minute holes 18 opened on the surface.

Subsequently, by applying a predetermined voltage between the aluminum base 10 and the aluminum oxide layer 12, the barrier layer 14 between the bottom of the minute hole 18 and the aluminum base 10 is removed.

After removing the barrier layer 14 in this manner, as shown in FIG. 4, the aluminum member is immersed in the temporary plating tank 22, and as shown in FIG. A semi-bright nickel plating layer 24 is grown through the micro holes 18. This half bright nickel plating layer
For example, saccharin (registered trademark) is added as a primary brightening agent to the plating bath of the temporary plating tank 22 for growing 24.

Subsequently, as shown in FIG. 4, the aluminum member was transferred to a secondary plating tank 26, and as shown in FIG. 3 (b), the surface of the aluminum oxide layer 12 was flattened on the semi-gloss nickel plating layer 24. The spreading bright nickel plating layer 28 is grown.

For the plating desire of the secondary plating layer 26 for growing the bright nickel plating layer 28, for example, butynediol is added as a secondary brightener in addition to the primary brightener, and sodium lauryl sulfate is added as an activator. An appropriate leveling agent is added.

[Problems to be Solved by the Invention] However, such a conventional method of forming a conductive film of aluminum or an aluminum alloy is excellent in that a nickel plating layer can be surely grown, but requires two plating tanks. Because of this, there is a problem that the plating equipment becomes large-scale, the position of the contact is easily shifted when the plating tank is moved, and the plating step is divided into two steps, so that the processing time is long and the cost is increased.

On the other hand, as for the conductive film, the bright nickel plating layer 28 is grown on the semi-bright nickel plating layer 24. There was a risk of failure.

The present invention has been made in view of such conventional problems, and provides a method of forming a conductive film of aluminum or an aluminum alloy material, which improves the efficiency of a plating process for forming a conductive film and improves the production yield. With the goal.

[Means for Solving the Problems] FIG. 1 is an explanatory view of the principle of the present invention.

In FIG. 1, first, as a pretreatment, a porous aluminum oxide layer 12 is formed on an aluminum substrate 10 made of aluminum or an aluminum alloy. The barrier layer 14 is removed.

Subsequently, it is immersed in a nickel plating bath to which a smoothing agent, a brightener (saccharin, butynediol, etc.) and an activator (sodium lauryl sulfate, etc.) are added, and a predetermined current density (for example,
0.15~0.45A / dm ²⁾ and the plating time (e.g., removed portions of the barrier layer 14 of aluminum matrix 10 under the control of 10-15 minutes), bright nickel plating spread flat further from the small hole 18 on the surface of the aluminum oxide layer 12 Grow layer 20.

[Operation] In the method for forming a conductive film according to the present invention, a conductive film formed by bright nickel plating can be grown in a single plating tank, so that the plating step is made more efficient,
Since the equipment is simplified, manufacturing costs can be reduced.

In addition, since the conductive film grows a single bright nickel plating layer on the aluminum oxide surface from aluminum base,
A highly reliable conductive film can be formed without problems such as peeling.

Example FIG. 2 is an example configuration diagram showing a process of a conductive film forming method of the present invention.

First, as shown in FIG. 2 (a), an aluminum member or an aluminum alloy member to be treated is subjected to an alumite treatment to form an aluminum oxide layer 12 of 10 μ degree on the surface of the aluminum substrate 10. As is well known, the aluminum oxide layer 12 includes a porous layer 16 having a plurality of minute holes 18 opened on the surface, and a barrier layer 14 in which the minute holes 18 are formed between the aluminum substrate 10.

Subsequently, as shown in FIG. 2 (b), a predetermined voltage is applied between the aluminum substrate 10 and the aluminum oxide layer 12, and the gap between the bottom of the minute hole 18 in the aluminum oxide layer 12 and the aluminum substrate 10 is applied. The barrier layer 14 is removed by the voltage drop to form a barrier layer removal hole 30.

Subsequently, after the formation processing of the via layer removing hole 30 shown in FIG. 2 (b) is completed, the aluminum member is immersed in a nickel plating bath to which a smoothing agent, a brightening agent and an activator are added, and FIG. The bright nickel plating layer 20 is grown as shown in FIG.

As a brightening agent added to a nickel plating bath for growing the bright nickel plating layer 20, saccharin which has been conventionally used as a primary brightening agent and butynediol which has been used as a secondary brightening agent are added. Also, sodium lauryl sulfate is added as an activator. Further, as a leveling agent, an appropriate leveling agent used for well-known nickel plating is added.

The plating process of growing the bright nickel plating layer 20 by immersing the aluminum member in a nickel plating bath to which such a smoothing agent, brightener and activator are added as shown in FIG. For example, if the density is 0.15 to 0.45 A / dm ² (1
The current density is controlled within a range of (00 × 100 current density per 100 mesh), and the plating time is controlled within a range of 10 to 15 minutes. The temperature of the plating solution is maintained at, for example, 55 ° C. and pH = 4.

As shown in FIG. 2 (c), the aluminum member immersed in the plating bath by the bright nickel plating process under such conditions was used as a barrier layer removal hole connected to the aluminum base 10.
The growth of the bright nickel plating layer 20 starts from the bottom of 30,
The fine holes 18 reach the minute holes 18 through the barrier layer removing holes 30, and further grow so as to spread flat on the surface of the aluminum oxide layer 12 from the openings of the minute holes 18. The growth of the bright nickel plating layer 20 causes the surface of the aluminum oxide layer 12 to have about 1
Flats are created that form contact contacts with a thickness of less than μ.

As for the current density and the plating time of the plating bath for growing the bright nickel plating layer 20, the optimum current density and the plating time can be determined together with other plating bath conditions through experimental processing.

[Effects of the Invention] As described above, according to the present invention, a conductive film formed by bright nickel plating can be grown in a single plating tank, so that the plating process can be made much more efficient and the equipment can be simplified. Process loss is small, and manufacturing costs can be significantly reduced.

In addition, since a single bright nickel plating layer is grown, there is no problem of peeling when used as a contact contact. Since the growth is a single bright nickel plating layer, the resistance value itself can be reduced.

[Brief description of the drawings]

 FIG. 1 is an explanatory view of the principle of the present invention; FIG. 2 is a structural view of an embodiment showing the processing steps of the present invention; FIG. 3 is an explanatory view of a conventional technique; 10: Aluminum base 12: Aluminum oxide layer 14: Barrier layer 16: Porous layer 18: Micro hole 20: Bright nickel plating layer 30: Barrier layer removal hole

Claims (1)

(57) [Claims] A porous aluminum oxide layer (1) is formed on an aluminum substrate (10) made of aluminum or an aluminum alloy.
After the formation of 2), the barrier layer (1) between the bottom of the minute holes (14) of the aluminum oxide layer (12) and the aluminum base is formed.
6) Removed, immersed in a nickel plating bath containing a brightener consisting of a leveling agent, saccharin and butynediol, and an activator consisting of sodium lauryl sulfate, to reduce the current density to 0.15 to 0.45 A / dm
^2, and the aluminum barrier layer removal portion from the green body (10), further flat spread bright nickel plating on the surface of the aluminum oxide layer from the small holes (14) (12) by controlling the plating time 10 to 15 minutes A method for forming a conductive film of aluminum or an aluminum alloy, wherein the layer (20) is grown.