KR900002110Y1 - Electroplating testing device - Google Patents

Abstract

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Description

High Speed Electroplating Test Equipment

1 is a plan view of a circular symmetric cell of the present invention.

2 is a cross-sectional view taken along the line A-A of FIG.

3 is a cross-sectional view taken along the line B-B in FIG.

4 is a reference circuit diagram of a high-speed electroplating test apparatus applying the plating bath of the present invention.

5 is a current density comparison table of the cathode of the cyclic symmetric cell according to the prior art and the present invention

Figure 6 (a) and (b) is an example of a conventional Hull (Hull Cell)

* Explanation of symbols for main parts of the drawings

1: cathode 2: anode

3: cathode support plate 4: anode support plate

5 threaded conductor 6 support

7: fixing screw 8: sealing ring

9: anode support 10: acid resistant valve

8: sealing ring 11: acid resistant pump

12 plating bath 13 rectifier

14: flow sensor 15: water tank

16 heater 17 thermocouple

18: temperature controller 19: three-way valve

20: plating liquid circulation pipe 21: connector

The present invention relates to a test apparatus required for evaluating and analyzing electrodeposition characteristics by changing the distribution of current density on a cathode in a single experiment, such as Hulsen used in electroplating experiments. The present invention relates to a high speed electroplating test apparatus.

In large electroplating seeds, zinc, zinc-based alloys, tin, and lead-tin alloys are applied at high speeds in the range of about 40-200 Amp / dm ² while continuously passing the iron plate coils through the plating bath. In the plating fixation, the electrodeposition characteristics are changed according to the plating liquid composition, the current density, the plating liquid temperature, the plating liquid shoe speed, and the like, and thus, it is necessary to experiment with these factors.

A conventionally known prior art is a Hull Cell developed by Hull in 1939. The characteristic of this device is that since the cathode surface is inclined about 49.5 ° to the anode surface, the current density is different on each part of the cathode when a constant current flows between the anodes. In other words, the current density is high in the region near the anode, and the current density is low in the remote region. The Hull Cell Scale shows the distribution of the current density on the cathode according to each position of the cathode and is used to analyze the distribution of the current density.

By using this cell, it is possible to minimize the number of experiments because the electrodeposition characteristics according to the current density can be grasped as a single experiment. However, the drawback of this cell is that the limiting current density decreases due to the thick diffusion layer formed on the cathode surface because the experiment is carried out in the stationary bath. Cell).

6 is a type of (a) agitating the plating liquid by flowing air or gas through the air inlet on the cathode side to the minute hole at the bottom of the cathode, and (b) circulating the plating liquid through the side hole. It is a form of circulation. The advantages of these devices can be tested up to about 5Amp / dm ² current density in the existing Hellcell. Compared to the 25Amp / dm ² area, the limiting current density is increased because the plating solution is stirred. However, these apparatuses cannot be used for high-speed plating tests of 40 Amp / dm ² or more because the plating liquid overflows out of the cell when the liquid is agitated severely. In addition, in the air agitation type, bubbles on the side of the cathode serve as a resistance, so when a large amount of air is injected, the distribution of the current density changes, and the actual current density on the cathode side is higher than the average current density.

In the plating solution circulation type, the flow of liquid at both ends of the cathode is stagnant and the flow velocity is not uniform through the front of the cathode, so it is difficult to accurately identify electrodeposition characteristics according to the current density. In addition, the disadvantage of these devices is that the distance between the cathode and the anode must be constant at all times, it is inconvenient to use a specimen of different thickness and to use a specimen of a prescribed thickness.

The electrodeposition experiment of the high current density of about 40-200Amp / dm ² is not possible with the Helsel type device developed previously. The object of the present invention is to compensate for these drawbacks of the prior art to provide a cyclic symmetrical hull cell (abbreviated as cyclic symmetric cell), which allows the experiment to be easily performed at high current density while retaining the advantages of the conventional hull cell.

This will be described in detail below.

The plating bath of the present invention is an octagonal pipe having an inner cross section as shown in the first diagram, and both ends thereof have a connecting pipe 21 to which the plating solution circulation pipe 20 can be attached, and the plating solution introduced into the plating bath from the pipe 20. The cathode and the anode can be installed in equilibrium with the inner wall of the plating vessel from the outside, as shown in FIG. 3, in the proper portion where this constant type is formed.

As shown in FIGS. 2 and 3, the octagonal inner shape is vertically symmetrical with respect to the imaginary plane which is perpendicular to the surface of the cathode 1 and connects the center of the cathode 1 surface and the center of the inclined surface of the anode support 9. The anode 1 surface has an inclination angle of 45 ° with respect to the anode 2 surface.

A cathode support plate 3 and an anode support plate 4 are respectively installed on the back surface of the cathode 1 and anode 2 based on the inside of the plating bath, and the threaded conductors 5 are formed on the cathode support plates 3 and 4, respectively. It is connected to enable the positive electrode (1, 2) plate to be energized, the sealing ring (8) is attached to the electrode support plate and the plated irradiation, the support (6) outside the electrode support plates (3, 4) and the support (6) Fixing screws 7 can be attached.

The present invention configured as described above attaches the electrode plates 1 and 2 to the triangular sides as shown in the third diagram, and places the electrode support plates 3 and 4 thereon, and tightens the support fixing screw 7. The sealing ring 8 is pressed to prevent leakage of the plating solution, and a screw-shaped wire 5 is inserted into the electrode support plates 3 and 4 to conduct plating through an electric current through the electrode plate. In the case of the reverse order. If the electrode plates 1 and 2 are too thin to bend, the secondary electrode plate may be attached to the back of the electrode to prevent bending, and between the electrode plates 1 and 2 and the electrode support plates 3 and 4 Since there is a gap to some extent, there is an advantage that an electrode plate having a different thickness can be used.

In particular, in the plating bath of the present invention, the plating solution is circulated inside the pipe, so that the plating solution is easily circulated at a high flow rate. Since the internal structure of the plating tank is symmetrical in octagonal shape, the type of plating solution is also symmetrical, so that the flow velocity near the cathode surface 1 is the region closest to the anode 2 and the home farthest, that is, the current density is the most. And at the lowest point coincide with each other. In addition, the anode pedestal 9 serves as a wall to prevent divergence of the electric field emitted from the anode 2, thereby preventing the current density of the end portion of the surface of the cathode 1 from becoming high, and the flow of the plating liquid is prevented. It prevents the concentration in the center of the plating bath, and in particular serves to distribute uniformly to the surface of the cathode (1).

4 is a reference circuit diagram of an experimental apparatus to which the symmetrical cell of the present invention is applied, so that the plating liquid can be circulated at high speed by a pump.

In this experiment, the acidic zinc plating solution was used to plate at 25 Amp / dm ² or less in a conventional air agitation method. When the plating solution was circulated at a speed of 2.5 m per second with respect to the cathode surface when the experiment was conducted, 200 Amp / A limit current density of dm ² or more was obtained and the distribution shown in FIG.

Since the present invention can circulate the plating solution at high speed into the plating bath of the present invention, the thickness of the diffusion layer formed on the cathode surface is made thinner, so that the current density is increased to 200 Amp / dm ² or more required in the conventional high speed plating. The high speed plating test is possible, and the flow rate distribution near the cathode is uniform, and it is possible to accurately measure the effect of changing the density, as well as to use various spreads with different electrode thicknesses.

Claims (1)

The internal structure of the plating bath is formed of an octagonal pipe, and the anode 2 and the cathode 1 are parallel to the inner wall thereof so as to maintain a 45 ° inclination angle at a predetermined portion where the plating liquid flows in the plating bath in a certain shape. And a cathode support (9) having an inclined surface parallel to the cathode (1) surface.