JPH08100297A - Method for controlling plating brightness in continuous copper electroplating - Google Patents

Abstract

PURPOSE: To enhance brightness quality by suppressing and preventing the variation in the brightness of a bright copper plated product produced in a continuous copper electroplating line. CONSTITUTION: The detection signals of the brightening agent content in a plating bath and the plating brightness on the outlet side of a plating bath tank are inputted to an arithmetic circuit 10. The quantity Q (=Q0 +Q1 ) obtd. by correcting the stationary replenishing quantity Q0 (the quantity set as a function of plating current, the width of a steel sheet and a line speed) of the brightening agent by a corrected replenishing quantity Q1 determined as a function of the change rate of the plating brightness with time is calculated. The brightening agent of the replenishing quantity Q is continuously fed into the plating bath within the range that the concn. of the brightening agent in the plating bath does not exceed a preset upper limit concn. under the regulation of the opening degree of a solenoid valve having the result of the calculation as the control signal of the solenoid valve 53 of a brightening agent supplying device 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the glossiness of a bright plated steel sheet produced by a continuous electrolytic copper plating line.

[0002]

2. Description of the Related Art When a copper-plated steel sheet produced by a continuous electro-copper plating line is required to have a glossiness, a brightening agent (an organic compound such as an azo type or a sulfa type having a polarizable group) is present in a plating bath solution. The composition containing) is added. FIG. 3 shows a general form of a continuous electroplating line for performing bright plating. 1 is a steel plate to be plated, 4 is a plating bath (an example of a 4-cell structure is shown in the figure), 5 is a brightener supply device, 6 is a plating solution analyzer for measuring the concentration of the brightener in the plating bath, and 8 is a gloss meter. is there. The brightener is from the tank 5 ₁ to the metering pump 5
The _2, or an electromagnetic valve 5 _3, are supplied to each cell of the plating bath 4. The steel plate 1 unwound from the pay-off reel 2 is introduced into the plating bath 4 through the pretreatment unit 3, passes through the bath, and then passes through the posttreatment unit 7 to be measured by the gloss meter 8 for the plating glossiness. It is wound up on the tension reel 9. The brightening agent added to the plating bath solution is consumed as the plating operation progresses, and the plating gloss decreases as the concentration in the bath decreases. Therefore, in order for the plated steel sheet to have a predetermined glossiness, it is important to maintain and control the concentration of the brightener in the plating bath within a certain concentration range that is sufficient.

Conventionally, as a method for controlling the concentration of the brightener, a constant amount Q empirically set as a function of the plating current, the width of the steel plate, the line speed (passing speed), etc.
An empirical method for recovering the concentration of ₀ (hereinafter “steady replenishment amount”) brightening agent while constantly adding it when the plating glossiness measured on the outlet side of the plating bath has decreased to a certain level. The method of replenishing a fixed amount of the brightener determined in 1. is performed. FIG. 4 shows the change over time of the plating glossiness (a in the same figure) and the supply pattern of the brightening agent (b in the same figure). The steady supply amount Q ₀ of the brightening agent is continuously added, and at a time t _L when the glossiness S has dropped to near the lower limit level S _L with the passage of time, a predetermined amount Q ′ of the spotting agent is applied. By making various inputs, the plating glossiness is restored.

[0004]

In the conventional method of controlling the concentration of the brightener in the plating bath as described above, it is possible to avoid the lack of the concentration of the brightener in the bath, but there is a change in the concentration. Therefore, the gloss of the plated product obtained is large.
Not only the variation within the same lot is large, but also variation between lots is accompanied, and it is difficult to secure uniform gloss quality. Further, the spotting addition of the brightening agent causes the concentration in the bath to become too high temporarily, which hardens the plating layer and causes the plating to peel off. The present invention has been made for the purpose of solving the above-mentioned problems relating to control of plating glossiness in continuous electrolytic copper plating.

[0005]

The method for controlling the plating glossiness of continuous electrolytic copper plating according to the present invention constantly measures the content of the brightening agent in the plating bath and the temporal change amount of the plating glossiness on the outlet side of the plating bath. The detected constant amount Q ₀ of the brightener, which is set as a function of the plating current, the width of the steel plate, and the line speed, and is corrected by the corrected amount Q ₁ of the correction, which is obtained as a function of the temporal change amount of the plating glossiness. (= Q ₀ + Q ₁ )
The above brightener is continuously added to the plating bath within a range not exceeding the upper limit of the concentration in the bath.

[0006]

According to the present invention, the brightener is continuously supplied while the steady supply amount Q ₀ of the brightener is constantly corrected based on the temporal change amount of the plating glossiness detected on the outlet side of the plating bath. Unlike the conventional method in which the shortage of the constant replenishment amount Q ₀ is compensated for by adding spots, the effect of always ensuring an appropriate amount of replenishment that follows changes in the concentration of the brightening agent in the bath is as follows. The medium concentration is stably maintained within a certain range with little vertical fluctuation, so that the variation in the glossiness of the plated product within and between lots is reduced, and the uniformity is improved.

The present invention will be described in detail below. As the brightening agent in the plating bath increases, the wear speed increases as the plating current increases, the plate width of the steel sheet to be plated increases, and the line speed (passing speed) increases. The quantity Q ₀ is expressed by the following equation [1] as a function of the plating current, the steel plate width, and the line speed. Corrected supply amount Q for correcting this steady supply amount Q ₀ to the optimum supply amount
₁ is expressed by the following formula [2] as a function of the change over time of the plating gloss detected at the outlet of the plating bath. The optimum replenishment amount Q obtained by correcting the steady replenishment amount Q ₀ with the corrected replenishment amount Q ₁ is given by the following equation [3].

[0008]

[Formula 1] Q ₀ = A · I · W · L (1) Q ₁ = B · δS / δt (2) Q = Q ₀ + Q ₁ (3) [where A and B are constants, I is the plating current, W is the plate width of the plated steel sheet, L is the line speed, and δS is the amount of change in glossiness over time of δt. ]

FIG. 2 shows the change with time of the plating glossiness according to the present invention (FIG. 2A) and the pattern of the brightener replenishment (FIG. 2B).
Is shown. The brightener is continuously supplied to the plating bath as a quantity Q corrected on the basis of the amount of change in the glossiness over time (FIG. 7B). The degree level is maintained (Fig. A). From the viewpoint of controlling the plating glossiness, an upper limit of the content of the brightening agent in the bath is not particularly required, but a problem due to an excessive content of the brightening agent in the plating bath (particularly in the plating layer In order to prevent (hardening and deterioration of plating adhesion), set the upper limit of the content according to the grade of the brightener, and replenish the brightener within the range not exceeding the upper limit of the content. You can limit it.

FIG. 1 shows an example of a glossiness control system for carrying out the present invention. The same parts as those in FIG. 3 are designated by the same reference numerals. Reference numeral 10 is an arithmetic circuit that controls the amount of brightener replenishment to the plating bath 4. The plating gloss of the plated steel sheet derived from the plating bath 4 is constantly detected by the gloss meter 8, and the detection signal a ₁ is input to the arithmetic circuit 10. The arithmetic circuit 10 calculates the correction supply amount Q ₁ (equation [2]) of the brightening agent from the temporal change amount (δS / δt) of the plating glossiness and the steady supply amount Q of the brightening agent.
An appropriate replenishment amount Q (Equation [3]) obtained by correcting ₀ (Equation [1]) with the correction amount Q ₁ is calculated. The operation result is
It is output as a control signal a ₂ of the electromagnetic valve 5 ₃ of the brightener supply device 5, and the opening of each valve is adjusted to replenish the appropriate amount Q of the brightener to each cell of the plating bath 4. The detection signal a ₃ of the brightener content in the bath by the plating solution analyzer 6 is input to the arithmetic circuit 10 and compared with the upper limit value of the brightener content, and the content in the bath exceeds the upper limit value. The opening degree of the electromagnetic valve 5 ₃ is adjusted so that it does not exist.

[0011]

[Examples] Bright plating was carried out by a continuous electrogalvanizing line equipped with the brightness control system shown in FIG. Steel plate width (W): 1000 mm Plating current (I): 85000 A Line speed (L): 8 to 12 m / min Plating bath liquid capacity: 100 m ³ Brightener supply Constant replenishment rate Q ₀ : 800 ml / Hr Constant of corrected supply Q ₁ B: 7.7 × 10 ⁵ ml ・ min Upper limit of content in bath: 15 ml / l (Detection value of concentration in bath by plating solution analyzer 6 is 10 ml / l
(If it reaches, it will be kept below 15 ml / l by suspending the feeding at that point.)

Table 1 shows the obtained plated steel sheet (total weight 200
(Ton / M) shows the measurement result of glossiness (measurement of glossiness is according to JIS K5400. However, incident angle: 20 °).
In the table, the comparative example is a plated steel sheet obtained by the conventional method of spot replenishing the brightening agent in the electroplating line of FIG. 3 (however, steady replenishment amount Q ₀ : 800 ml / Hr, replenishment amount Q of spot). ': About 18 to 36 l / time). The plated steel sheet of the invention example has little variation in glossiness and is excellent in gloss quality uniformity. Further, by avoiding excessive addition of the brightening agent in the bath, hardening of the plating layer and peeling of the plating are prevented.

[0013]

[Table 1]

[0014]

EFFECTS OF THE INVENTION According to the present invention, by continuously supplying the brightening agent according to the consumption rate of the brightening agent in the plating bath, the variation in the glossiness of the electrolytic copper-plated product is reduced, and the glossiness is improved. The homogeneity of the quality is improved, and the excessive addition of the brightening agent and the resulting hardening of the plating layer and peeling of the plating layer are prevented. Furthermore, in contrast to the conventional method, in which the operation for measuring the glossiness off-line and the spot replenishing work for the brightening agent in the plating line require at least two workers, the present invention provides It is easy to fully automate the measurement of the degree and the replenishment work of the brightener, and a great effect can be obtained in labor saving.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a glossiness control system in a continuous electrolytic copper plating line for carrying out the present invention.

FIG. 2 is a graph schematically showing a change with time of a brightener addition pattern and plating glossiness according to the present invention.

FIG. 3 is a diagram showing a glossiness control system of a conventional continuous electrolytic copper plating line.

FIG. 4 is a graph schematically showing a temporal change of a brightener addition pattern and a plating glossiness by a conventional method.

[Explanation of symbols]

1: Steel plate to be plated, 4: Plating bath, 5: Brightening agent supply device, 5 ₁ : Brightening agent tank, 5 ₂ : Metering pump, 5 ₃ : Electromagnetic valve, 6: Plating solution analyzer, 8: Gloss meter, 10: arithmetic circuit,

Claims (1)

[Claims] 1. A brightening agent set as a function of a plating current, a steel plate width, and a line speed by constantly detecting a content of the brightening agent in a plating bath and an amount of time-dependent change in plating glossiness on the outlet side of the plating bath. Corrected replenishment amount Q obtained as a function of steady-state replenishment amount Q ₀ of
_In continuous electrolytic copper plating, which is characterized in that a quantity Q (= Q ₀ + Q ₁ ) of the brightener corrected in ₁ is continuously added to the plating bath within a range not exceeding the upper limit of the concentration in the bath. How to control plating gloss.