JPS5938397A - Electroplating device - Google Patents

Abstract

PURPOSE:To make the plating current density in a cathode uniform and to form a plating layer having a uniform thickness in the stage of electroplating, by dispposing a perforated electrode between the cathode and the anode near the cathode, and impressing a positive voltage on the cathode. CONSTITUTION:An anode (consumable anode or insoluble anode) 3 and a cathode 4 which is a material to be plated are disposed in the plating soln. 2 in a plating cell and a perforated electrode plate 6 such as an expanded metal made of Ti is disposed between the same near the electrode 4. A voltage of a power source 5 for plating current is impressed between the anode 3 and the cathode 4, and such a voltage at which the electrode plate 6 has a positve voltage is impressed between the cathode 4 and the plate 6 by a power source 7 and the plating operation is performed. Since the plate 6 exists, the curent density on the surface of the cathode 4 has an extremely small difference between the end part and the central part, and the plating layer having a uniform thickness is formed over the entire surface of the cathode 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electroplating device that performs plating by applying a DC voltage between a cathode and an anode.

In this type of electroplating apparatus, for example, as shown in FIG. 1, a flat cathode a and an anode are immersed in a plating solution C in a state where they face each other, and a DC voltage is applied between the two electrodes a and b. It is. However, in this case, the distribution of electric lines of force between the cathode a and the anode becomes as shown by the broken line in the figure, and the current density at the cathode a becomes larger toward the periphery. For this reason, conventionally the cathode 8
The thickness of the plating layer formed on the surface is thin at the center and extremely thick at the periphery, making it difficult to achieve uniform plating.

The present invention has been made in view of the above circumstances, and therefore, its object is to provide an electroplating device that can make the current density in the cathode as uniform as possible, and thereby make the thickness of the plating layer uniform.

A first embodiment of the present invention will be described below with reference to FIGS. 2 to 6. 1 is a plating tank, and 2 is a plating solution stored in the plating tank 1. This plating solution 2 uses, for example, a so-called matte Watt bath for nickel plating. 3 is an anode placed in the plating solution 2, which is, for example, about 150III
It is constructed from an electrolytic nickel plate with a width of 11 mm. 4 is a cathode immersed in plating solution 2, which has a width of about 150 m, for example.
It is constructed of a copper-clad laminate with a height of about 170 mm and is arranged to face the anode 3 with a gap of about 160 mm. Reference numeral 5 denotes a first power supply device, which applies a predetermined DC voltage between the anode 3 and the cathode 4. Reference numeral 6 denotes a porous electrode immersed in the plating solution 2, which has approximately the same size as the cathode 4, that is, about 150 mm in width.

It is constructed of titanium expanded metal with a height of about 160 mm, and is disposed substantially parallel to and facing the cathode 4 with an interval of about 30 ml. Reference numeral 7 denotes a second power supply device, which applies a predetermined voltage to the porous electrode 6 so as to be positive with respect to the cathode 4.

In the above configuration, the output voltage V1 of the first power supply device 5 is set to about 3.3V, the output current A1 is set to about 6.2A, and the output voltage V2 of the second power supply device 7 is set to about 2.3V. 2V
The output current A2 is set to about 1. OA, and the cathode 4 was nickel plated at a cathode current density DkL of 3 A/dm2. As a result, the layer thickness of the plating layer formed on the surface of the cathode 4 is determined by the five vertical lines a to e formed at equal intervals and the three horizontal lines A to C formed at equal intervals as shown in FIG. Measurements were taken at each intersection. The measurement results are shown in solid lines in FIGS. 4 to 6. For comparison, the thickness of the plating layer formed using a conventional plating device (which differs from the one in this example in that it does not have a porous electrode 6, but otherwise under the same conditions as in this example) is also shown. were measured in the same manner as described above, and the results are shown in broken lines in FIGS. 4 to 6. As is clear from these measurement results, each horizontal line A
It is recognized that the difference in layer thickness between the center and both sides on C to C is significantly smaller in this example than in the conventional one. That is, in this embodiment, the uniformity of the plating layer thickness on the cathode 4 can be greatly improved. This is because the porous electrode 6 has many openings, so the anode 3
This has almost no effect on the distribution of the lines of electric force linearly connecting the cathode 4 and the cathode 4, and the electric lines of force from the porous electrode 6 are added to the cathode 4, making the current density at the cathode 4 uniform overall. This is thought to be for the purpose of

7 to 10 show a second embodiment of the present invention, and the difference from the first embodiment is that the porous electrode 8 has a width of approximately 300 m.
It is constructed of titanium expanded metal with a diameter of 1.5 m and is placed over the entire width of the plating tank 1.

In this configuration, the output current A1 of the first power supply device 5 is approximately 6.9A, and the output current A1 of the second power supply device 7 is approximately 6.9A.
2 was set at about 0.3 A, and the cathode 4 was plated. Then, the thickness of the plating layer was measured at each point on the cathode 4 in the same manner as in the first embodiment, and the results are shown in solid lines in FIGS. 8 to 10. For comparison, the measurement results of a porous electrode formed to the same size as the cathode 4 and plated under the same conditions as in this example are also shown in FIGS. 8 to 10 with dashed lines. . From these measurement results, it is recognized that even when the porous electrode 8 is formed larger than the cathode 4, the thickness of the plating layer can be made uniform. Therefore, when sequentially plating multiple types of cathodes with different sizes, it is possible to determine which cathode 4 by setting the size of the porous electrode 8 to be approximately equal to or larger than the largest cathode 4. Since the porous electrode 8 can be made approximately the same size or larger than the cathode 4, a uniform plating layer can always be formed without replacing the porous electrode 8 depending on the size of the cathode 4.

As described above, the present invention is characterized in that a porous electrode is disposed between an anode and a cathode, and a predetermined voltage is applied to the porous electrode so as to be positive with respect to the cathode. , the current density at the cathode can be made as uniform as possible between the central part and the peripheral part, thereby making it possible to make the plating layer thickness uniform.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal sectional view showing a conventional electroplating device;
2 to 6 show a first embodiment of the present invention, FIG. 2 is a schematic vertical cross-sectional view of an electroplating device, FIG. 3 is a front view of a cathode, and FIGS. 4 to 6 are plating devices. Graphs showing the measurement results of layer thickness, FIGS. 7 to 110 show the second embodiment of the present invention, FIG. 7 is a partial perspective view of the electroplating device, and FIGS. It is a graph showing measurement results. In the figure, 3 is an anode, 4 is a cathode, and 6 is a porous electrode. Figure 2 Figure 1 17.5 Figure 3 Figure 4 (P) Figure 5 (p) Figure 6 (μ) Bird 7 Figure 8 (211 (μ) Bird 9 Figure (P) ocae

Claims (1)

[Claims] 1. In a device in which plating is performed by applying a DC voltage between an anode and a cathode, a porous electrode is disposed between the anode and the cathode, and a porous electrode is provided to the porous electrode with respect to the cathode. An electroplating device characterized in that a predetermined voltage is applied so as to be positive. 2. The electroplating apparatus according to claim 1, wherein the porous electrode is formed to have a size substantially equal to or larger than that of the cathode.