JPH034639B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] Industrial Application Field The present invention relates to a method of subjecting the surface of an article to electrolytic treatment such as electroplating.

Prior Art When performing electrolytic treatment such as electroplating or electropolishing on the surface of an article, it is necessary to adjust the current density of the surface to be treated within an appropriate range in order to obtain a good electrolytically treated surface. Indispensable. In order to know the current density in such electrolytic treatment, there is a method of calculating it from the area of the surface to be treated and the total current value. There is a problem in that the current is concentrated and only a small amount of current flows to the recesses or the back surface, so it is not possible to obtain a good electrolytically treated surface just by knowing the average current density as described above.

Therefore, when performing electrolytic treatment, it is important to know the local current density at different locations on the contact surface between the conductor to be treated and the electrolytic bath. As a means of determining current density, even if there was a method to measure it in a laboratory, the reality is that there is still no measurement method that can be used in industrial operations.

In contrast, one of the inventors of the present invention proposed a bipolar electrode type sensor, in which a pair of mutually insulated conductor electrodes are arranged facing each other at a predetermined distance, on the liquid contact surface of the conductor to be measured for current density. The sensors are placed close to each other in an electrolytic solution, and a potential gradient proportional to the current density in the solution generated by the current flowing through the electrolytic solution is detected as a potential difference between the electrodes of the sensor, and this potential difference signal is detected in advance. By substituting the obtained potential difference-current density function measured for the same electrolytic solution, the current density in the liquid near the liquid contact surface of the conductor to be measured is determined, and from this, a specific point on the liquid contact surface can be determined. It has been found that a means for approximately measuring the density of passing current is industrially practical. and,
He invented a current density measuring device based on this principle and has filed a separate patent application (Japanese Patent Application Laid-open No. 27655/1983).

However, even if the current density at the surface in contact with the liquid can be determined by such means, the current must be controlled based on the judgment of the electrolytic engineer in order to optimally apply the current to the object to be electrolytically treated. It was necessary to adjust the electrolytic treatment time carried out.

Problems to be Solved As mentioned above, in the electrolytic treatment of articles according to the prior art, there was no known accurate means of measuring current density, and the accuracy of estimating the average current density was not sufficient. In order to ensure complete electrolytic treatment, it was necessary to set operating conditions such that the amount of current applied was excessive.

As a result, the treated articles are given an excessive quality, for example, the plating film is too thick, and on the other hand, this results in waste of raw materials and energy and a decrease in operational efficiency.

Therefore, the present invention aims to provide a highly reliable electrolytic treatment method that can perform good and economical electrolytic treatment on objects to be treated by using the current density measurement method previously invented by the present inventors. It is something to do.

[Structure of the invention]

Means for Solving the Problems The electrolytic treatment method of the present invention that can achieve the above object uses a current density measuring sensor having two wetted electrodes that are insulated from each other and are spaced apart from each other by a predetermined distance. An integrating circuit is provided close to the surface of the article to be electrolytically treated, and calculates the output signal value from the sensor to generate a current density signal, and compares the current density signal with a set value input and stored in advance. supplying current to the article to be electrolytically treated through a control device comprising at least a comparison circuit that generates a control signal and a current control circuit that controls an electrolytic current in response to the control signal; This is a characteristic feature.

Example The present invention will be further explained below with reference to FIG.

The current density measurement sensor S used in the present invention includes, for example, a tip of an insulating cylindrical body 1;
Two electrodes 2 in contact with the liquid are provided at a predetermined distance, for example, about 5 mm, and are insulated from each other. The wetted electrode 2 is desirably made of a corrosion-resistant metal such as platinum, or a metal of the same type as the ions contained in the electrolyte, and is preferably made of a metal that will not contaminate the electrolyte even if eluted. It is preferable that Further, an electric wire 3 for transmitting a detected voltage signal is connected to the liquid contact electrode, and is configured to be guided to the outside of the electrolytic treatment tank B.

Moreover, the control device R used in the present invention
is for controlling the magnitude of electrolytic current,
The current supply is automatically adjusted to maintain the appropriate current density to achieve the desired electrolytic treatment effect. The control device R includes an integrating circuit 4 that receives an output voltage signal detected by the current density measurement sensor S, calculates the output voltage signal, and generates a signal corresponding to the current density; It has an area 5' for inputting and storing the current density setting value required for the integration circuit 4, and receives the current density signal generated by the integrating circuit 4, compares it with the setting value, and determines whether the current density signal is smaller than the setting value or not. It comprises a comparator circuit 5 which generates a control signal for increasing or decreasing the electrolytic current depending on whether it is large, and a current control circuit 6 which operates to increase or decrease the electrolytic current in response to the control signal.

In carrying out the electrolytic treatment method of the present invention, the article C to be electrolytically treated is immersed in the electrolytic bath B facing the electrode A.
When a sample of the same shape is subjected to electrolytic treatment, it is necessary to investigate in advance how the current density differs at each part of the surface in contact with the liquid, and select a position that shows a typical current density, for example, the average current density. I'll keep it. Then, the liquid contact electrode 2 of the sensor S is fixed in close proximity to a representative position of the article C to be processed, the sensor S and the control device R are connected, and the power source E is connected to the control device R.
The electrolytic treatment is performed by connecting so that an electrolytic current flows through the current control circuit 6 to the article C to be treated.

When the electrolytic current flows in this way, a potential gradient corresponding to the current carrying resistance and current density is generated in the electrolytic solution near the liquid contact surface of the article C to be processed, but the tip of the sensor S is placed at a predetermined distance. A potential difference corresponding to the above-mentioned potential gradient is detected between the two liquid contact electrodes 2 separated from each other, and this is inputted to the integrating circuit 4 as a voltage signal via the electric wire 3.

The voltage signal input to the integrating circuit 4 is converted into a current density by a function including the characteristic constant of the sensor S used and the characteristic constant of the electrolytic solution used, and is output as a current density signal. This current density signal is input to the comparator circuit 5, and its storage area 5' stores the current density value necessary to obtain a predetermined electrolytic treatment effect, for example, in the case of plating, a plating film with a good surface condition. is set and compared with this setting value. When the current density signal is smaller than the set value, a control signal is output to increase the electrolytic current, and when the current density signal is larger than the set value, a control signal is outputted to decrease the electrolytic current. A control signal is output.

When such a control signal is input to the current control circuit 6, the current control circuit 6 operates to increase or decrease the current in response to the control signal.
The format of the control signal at this time may be a proportional signal centered on the set current density value, or may be a three-point signal of increase-neutral-decrease. According to the type and structure of the current control circuit 6, it is desirable to select and adopt a signal format that allows the most effective control of the electrolytic current.

Function According to the electrolytic treatment method of the present invention, the strength of the current is automatically adjusted so that representative positions of the article to be electrolytically treated are subjected to the electrolytic treatment at a preset current density. Therefore, even if there are fluctuations in the power supply voltage or changes in the number of items to be processed simultaneously during electrolytic treatment, these fluctuations are automatically compensated for and a certain level of electrolytic treatment effect can be maintained. You can expect it.

〔Effect of the invention〕

The electrolytic treatment method of the present invention detects the current density on the liquid-contact surface of the article to be electrolytically treated and automatically compensates so that the current density on the surface of each article and each part remains steady. Therefore, the current density does not change even if there are unexpected fluctuations such as fluctuations in the power supply voltage or fluctuations in the number of articles being processed in parallel at the same time. Therefore, uniform electrolytic treatment is guaranteed for each article.

Therefore, variations in quality are reduced and excessive quality does not occur, making it possible to perform highly efficient and economical electrolytic treatment.

[Brief explanation of the drawing]

FIG. 1 is a block diagram for explaining the structure of the electrolytic treatment method of the present invention. A...electrode, B...electrolytic cell, C...article to be electrolytically treated, E...power source, S...sensor for current density measurement, R...control device, 1...cylindrical body, 2...connection Liquid electrode, 3... electric wire, 4... integral circuit. 5... Comparison circuit, 6... Current control circuit.

Claims (1)

[Claims] 1. A current density measuring sensor having two electrodes in contact with liquid that are insulated from each other and separated by a predetermined distance is provided close to the surface of the article to be electrolytically treated, and the output signal value from the sensor is An integrating circuit that calculates and generates a current density signal, a comparison circuit that compares the current density signal with a pre-input/stored setting value and generates a control signal, and controls the electrolytic current in response to the control signal. An electrolytic treatment method characterized by supplying current to the article to be electrolytically treated via a control device comprising at least a current control circuit.