JP3901641B2 - Surface area measuring method, surface area measuring apparatus, and plating method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention mainly relates to a method and apparatus for measuring the surface area of an object to be measured in a pre-process of surface treatment using an electrochemical reaction, and a method for plating an object to be processed using an electrochemical reaction.
[0002]
[Prior art]
Surface treatment using an electrochemical reaction such as plating, alumite, electropolishing, etc. must be performed while controlling the current density (A / dm ² ) on the surface of the object to be treated, but this cannot be measured directly. The total current (A) obtained by multiplying the current density (A / dm ² ) by the surface area (dm ² ) of the object to be processed is measured. Therefore, accurately grasping the surface area of the workpiece in such surface treatment is a very important issue in improving the accuracy and quality of the surface treatment.
[0003]
Conventionally, as a method of measuring the surface area of an object to be processed (also referred to as an object to be measured in surface area measurement), a method of measuring a three-dimensional shape using a sensor or a CCD camera and analyzing it by a computer, or a CAD drawing A method for analyzing data using a computer has been proposed.
However, this method requires many expensive devices such as sensors, CCD cameras, and computers, and requires more advanced measurement techniques and mathematical knowledge, so it is not always suitable for work sites where plating is performed. Not.
In addition, since the number of processed objects having the same shape tends to be reduced due to the recent demand for high-mix low-volume production, the measurement method that requires time for one processed object deteriorates the profitability.
[0004]
For these reasons, when processing a workpiece having a complicated shape, the worker roughly estimates the surface area and often adjusts the current by visually determining the bubbles generated during the plating process. . However, such a method requires a high degree of skill and the plating layer of the product is extremely varied.
[0005]
In order to solve such a problem, as disclosed in Patent Document 1, a method for electrochemically measuring the surface area of an object to be processed immersed in an electrolytic solution has been proposed. That is, in this method, a current value is obtained by immersing a plurality of metal test pieces having known areas and different areas in an electrolyte solution, applying a constant voltage under predetermined electrolysis conditions, and measuring the current at that time. And the area of the object to be measured by applying the current value when the same voltage is applied to the object to be measured of the unknown area under the same electrolysis conditions to the relational expression. It is what you want.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 56-160608
[Problems to be solved by the invention]
However, when a rolled flat copper plate as in Patent Document 1 is used as an object to be measured, a relatively accurate measurement result is easily obtained, but an accurate measurement result is not necessarily obtained for an object having a complicated three-dimensional shape. I can't. This is because if the distance between the object to be measured and the electrode is different, the resistance value of the electrolyte solution is also different, so that the surface current density is not constant.
[0008]
Note that the present inventor has proposed a method of arranging the electrodes 51 on both sides of the object to be measured 52 as shown in FIG. 11A in order to offset the influence of the distance between the electrode and the object to be measured, or FIG. The method of surrounding the entire object 52 to be measured with the electrode 51 as shown in FIG. However, in any case, it has been confirmed that the resistance value greatly increases nonlinearly as the position of the object to be measured is shifted from the center.
Therefore, in the case of an object having a complicated three-dimensional shape, the surface area cannot be accurately measured because the distance between each part of the object to be measured and the electrode is not constant. That is, even when such an apparatus is used, only a thin plate having the same thickness as that of the test flat plate used as a reference or a thin plate having a thickness that does not affect the distance from the electrode is accurately measured. There is a problem that can not be.
[0009]
In addition, since such a problem is caused by the fact that the current density is not uniform on the surface of the object to be measured, the same phenomenon occurs in the plating method using the electrolysis reaction, and the surface of the object to be processed is uniform. There is a problem that a thick plating layer is not formed.
[0010]
In view of the above problems, an object of the present invention is to accurately measure the surface area of an object to be measured which is mainly subjected to surface treatment using an electrochemical reaction.
Another object of the present invention is to form a uniform plating layer on the surface of an object to be processed when an object to be processed is plated using an electrochemical reaction.
[0011]
[Means for Solving the Problems]
The present invention has been made in order to solve the above-mentioned problems, and the object to be measured and the electrode are immersed in the electrolyte solution, and a voltage is applied to the object to be measured and the electrode in the electrolyte solution, and the energized state at that time In the surface area measuring method for measuring the surface area of the object to be measured, the electrodes are arranged at two upper and lower positions at each of the four corners of the water tank, and four baffle plates that shield the electrodes from the center of the water tank at the four corners of the water tank. A surface area measuring method is provided, characterized in that a voltage is applied in a state where resistance is provided to the passage of ions by forming an elongated channel between an edge of the baffle plate and a water tank .
[0013]
Preferably, the flow of the electrolyte solution is suppressed so that the current distribution in the region where the object to be measured is immersed is within a range of ± 5%. The current distribution in the present invention refers to a current value that flows when a flat plate electrode is installed in a region where the object to be measured is immersed, and a constant voltage is applied between the flat plate electrode and the surrounding electrode. In this case, the variation in the region is measured. Moreover, the range of ± 5% means the percentage when the difference between the maximum value and the minimum value of the measured current value is divided by the current value measured when the plate electrode is installed at the center of the water tank. It shall be said.
[0014]
Further, the present invention is a surface area measuring device used for measuring the surface area of a measured object from an energized state by applying a voltage to the measured object and an electrode immersed in an electrolyte solution, There are provided a water tank for containing the electrolyte solution, electrodes arranged at two upper and lower positions at the four corners of the water tank, and four baffle plates that shield the electrodes from the center of the water tank at the four corners of the water tank, A surface area measuring device is provided in which an elongate flow path is formed between the edge of the baffle plate and the water tank so as to provide resistance to passage of water .
[0015]
Good Mashiku is provided with an auxiliary electrode on the bottom of the tank, said the electrode and the auxiliary electrode and that is configured to be capable of adjusting the voltage separately.
[0016]
Preferably, the baffle plate is provided so that a current distribution in a region where the measurement object is immersed is within a range of ± 5%.
[0017]
Furthermore, the present invention is a plating method in which a workpiece and an electrode are immersed in an electrolyte solution, a voltage is applied to the workpiece and the electrode in the electrolyte solution, and metal ions in the electrolyte solution are deposited on the surface of the workpiece. In the method, the electrodes are arranged at two upper and lower positions in each of the four corners of the water tank, and further, four baffle plates that shield the electrodes from the central part of the water tank are arranged in the four corners of the water tank, and the edge of the baffle plate and the water tank A plating method is provided, which is performed in a state where resistance is given to the passage of ions by forming a long and narrow channel between the two.
[0018]
Preferably, an auxiliary electrode is further disposed below the workpiece, and the voltage of the electrode and the auxiliary electrode is adjusted separately.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a surface area measuring apparatus according to the present invention will be described with reference to the drawings, and an aspect of a surface area measuring method using the apparatus will be described.
[0020]
FIG. 1 is a perspective view showing an embodiment of a surface area measuring apparatus according to the present invention, FIG. 2 is a plan view of the surface area measuring apparatus, and FIG. 3 is a cross-sectional view taken along line AA of FIG.
As shown in FIGS. 1 to 3, the surface area measuring device 1 includes a water tank 2 having a square cross section, and a total of eight electrodes 3, 3. Four baffle plates 4, 4... For shielding the electrode 3 from the center of the water tank at the four corners of the water tank, and an auxiliary electrode 7 placed on the bottom of the water tank 2 are provided. Furthermore, a rack 5 for supporting the object to be measured (not shown) in the electrolyte solution, and a power supply rod 6 for supporting the rack 5 and for energizing the object to be measured through the rack 5 are provided. ing.
And when measuring a surface area, as shown to FIGS. 1-3, the electrolyte solution 10 set to the predetermined temperature and density | concentration will be satisfy | filled to the water tank 2. As shown in FIG.
[0021]
In this embodiment, the baffle plate 4 is employ | adopted as a distribution suppression means. Specifically, the baffle plate 4 shields the electrode 3 from the object to be measured so that the electrode does not directly face the object to be measured, and allows the electrolyte solution 10 to pass through the electrode side region (also referred to as an electrode region). ) 20 and a region to be measured (also referred to as a region to be measured) 30, and further provided to suppress the flow of the electrolyte solution 10 between these two regions.
[0022]
As shown in FIG. 2, the baffle plate 4 of the present embodiment is a substantially flat plate with bent edges at both ends, and the electrolyte solution 10 flows between the edges at both ends and the water tank 2. An elongate flow path 11 that can be suppressed is formed, and the electrode region 20 and the measured object region 30 can only flow through the flow path 11.
[0023]
The shape of the electrode 3 is not particularly limited, but it is preferable to use an electrode having a small area so that the electric resistance does not become excessive, and this allows the object to be measured to move in parallel at an equal distance from the electrode. It is believed that the so-called Wagner length effect that occurs can be reduced.
[0024]
The auxiliary electrode 7 is installed to further correct the Wagner length effect caused by the position of the object to be measured with respect to the electrode 3 and the influence of Ohm's law, and the shape is not particularly limited.
[0025]
The electrode 3 and the auxiliary electrode 7 are connected to a power supply device (not shown) so that a predetermined voltage is applied to the object to be measured. That is, a variable resistor (not shown) is interposed between the power supply device and each electrode or auxiliary electrode, so that different voltages can be applied to the electrode 3 and the auxiliary electrode 7, and the electrode 3 Also, a different voltage can be applied to the upper electrode 3a and the lower electrode 3b.
[0026]
The voltage applied to each electrode should be appropriately adjusted according to various conditions such as the shape and size of the water tank, the size and arrangement of the electrodes, and the shape of the rack, but is applied to the upper electrode 3a. Assuming that the voltage is V1, the voltage applied to the lower electrode 3b is V2, and the voltage applied to the auxiliary electrode 7 is V3, V1: V2 is 1: 0.1 to 1: 1, and V1: V3 is 1 A range of 0 to 1: 1 can be exemplified as a suitable voltage ratio.
[0027]
The power supply device is not particularly limited as long as a predetermined voltage can be applied to the object to be measured and the electrode.
[0028]
Moreover, it does not specifically limit as the electrolyte solution 10, For example, a sodium hydroxide solution, a phosphate solution, etc. can be used. The electrolyte solution is maintained at a constant electrolyte concentration by a water supply device (not shown) and an electrolyte solution supply device (not shown) linked with a monitor electrode (not shown), and a thermometer (not shown). The temperature is kept constant by a heater (not shown) in conjunction with).
[0029]
According to such a surface area measuring device 1, since the flow of the electrolyte solution 10 is suppressed by the baffle plate 4, the current distribution in the water tank 2 is made uniform.
[0030]
Next, a surface area measuring method using the surface area measuring device of such an embodiment will be described.
[0031]
First, a rack 5 on which an arbitrary object to be measured is hung is hung on a power supply rod 6 and immersed in an electrolyte solution 10, and the height and front / rear / left / right positions of the object to be measured are changed with a constant voltage applied. The current value is measured, and the voltages of the upper electrode 3a, the lower electrode 3b, and the auxiliary electrode 7 are adjusted so that the fluctuation of the current value becomes small.
[0032]
Next, an arbitrary rack is used as a reference rack, the reference rack is hung on the power supply rod 6 and immersed in the electrolyte solution, and a current value is measured by applying a certain voltage. Further, a plurality of racks having the same shape are measured in the same procedure, and an average value is obtained and set as a standard rack current value (Ls).
A plurality of reference measurement objects with known surface areas (for example, 0.5 dm ² / sheet × 20 sheets) are sequentially placed on the reference rack one by one, and the current value is measured with the rack immersed in the same water depth. Then, a relational expression (Fs) between current and surface area is obtained.
The relational expression (Fs) is expressed as, for example, As = f (x) + C (where As is the surface area, x is the current value, and C is the area of the standard rack alone).
[0033]
Then, the current value (Lv) is measured for the racks that are actually used (if there are a plurality of racks). A rack in which an abnormal current value is detected is excluded as a defective rack. The relational expression for the reference rack is obtained by multiplying the constant term of the relational expression (Fs) by the ratio (Lv / Ls) between the current value (Ls) of the reference rack and the current value (Lv) of the rack to be used. (Fv) is corrected according to the size and shape difference of each rack actually used.
[0034]
In this way, since the relational expression (Fs) of the reference rack is corrected for each rack actually used, the current value is obtained in a state in which an object to be measured whose area is unknown is suspended from the rack. By measuring (Lv), the surface area of the object to be measured can be accurately calculated based on the relational expression (Fs). Even when there are other factors to be corrected, such as the material of the rack, they are set or corrected as necessary.
[0035]
According to such a surface area measuring apparatus and measuring method, the current distribution in the water tank is made uniform, and the current density in each part of the object to be measured is substantially constant, and the object to be measured has a complicated three-dimensional shape. It is possible to accurately measure the surface area.
This is because the flow of the electrolyte solution is suppressed by the baffle plate 4 so that the distance between the electrode and the object to be measured is apparently a long distance, or the resistance increases in inverse proportion to the distance from the electrode. This is presumed to be due to the generation of components. And in addition to such an effect | action, when the electrode 3 is arrange | positioned substantially uniformly in the water tank 2, it is estimated that the current distribution is made uniform.
[0036]
In addition, since the current distribution in the water tank is made uniform, the surface area can be accurately measured even when the position of the object to be measured in the water tank changes.
[0037]
In addition, although the said embodiment demonstrated the case where the baffle plate 4 was used as a distribution suppression means, this invention is not limited to this.
Accordingly, as another distribution restraining means, for example, as shown in FIG. 4, a cylindrical body 41 that can accommodate an electrode, and lid bodies 42 provided at both ends of the cylindrical body 41. It is also possible to use a configuration in which the gap with the lid 42 is separated so as to form the flow path 11 having a predetermined width. According to the distribution restraining means having such a configuration, there is an advantage that it is not necessary to install a large baffle plate in the water tank, and the inside of the water tank can be widely used.
[0038]
As another form of the flow suppressing means, the flow path may have a shape that increases the flow distance between the electrode region and the measured object region in addition to slightly narrowing the width. When the flow distance is increased, the distance between the electrode and the object to be measured is increased and the influence of Ohm's law can be alleviated, and the effect can be exhibited more remarkably by using a narrow flow path.
[0039]
Further, the shape of the electrode 3 is not particularly limited, and when the cylindrical body 41 and the lid body 42 as shown in FIG. It is good also as the cylindrical electrode 31 which is easy to do.
[0040]
Furthermore, it is preferable to arrange | position the position and quantity which provide an electrode in the position where the inside of a water tank becomes as uniform as possible. In the above embodiment, a total of eight electrodes are evenly arranged in the water tank, but the number of electrodes may be less than that or more.
Moreover, it does not specifically limit about the shape of a water tank, It can be set as a cylindrical shape and other arbitrary polyhedral shapes.
[0041]
In the embodiment of the surface area measuring method, the relational expression (Fs) is multiplied by the ratio (Lv / Ls) between the current value (Ls) of the reference rack and the current value (Lv) of the rack to be used. The relational expression (Fs) for the standard rack was corrected for each rack actually used. However, the current value was measured by multiplying each rack used by a plurality of reference measurement objects in order, and the current was directly measured. And the relational expression (Fv) of the surface area.
[0042]
Further, in the above embodiment, the surface area is calculated by measuring the current value with a constant voltage, but the present invention is not limited to this, and the voltage of the object to be measured is measured by measuring the voltage with a constant current. The surface area may be calculated.
[0043]
Further, in the above embodiment, it is suitable when the object to be plated is a measurement object, but the present invention is to measure the object to be surface-treated using these electrochemical reactions. However, the measurement object can be any object whose surface area is difficult to measure.
[0044]
In the present invention, the surface area can be measured by measuring, for example, the current value of the conductive measurement object as in the above embodiment, but only such a conductive measurement object is limited as the measurement object. It is not a thing. That is, according to the present invention, an insulating substance can be used as an object to be measured. Specifically, the electrostatic capacity in a state where a voltage is applied is measured by the same method, and the electrostatic capacity is determined as a dielectric. By dividing by the rate, the surface area of the measurement object can be measured.
[0045]
Here, the current distribution in the water tank was measured using a test apparatus as shown in FIG. 5 in order to verify that the current distribution in the water tank was made uniform when the baffle plate was installed as a flow suppressing means.
FIG. 5 is a perspective view showing an outline of the test apparatus. The test apparatus surrounds the water tank 2, a plate electrode (cathode) 15 disposed in the center of the water tank 2, and the plate electrode 15. A rectangular frame type electrode (anode) 3 and a square frame type baffle plate 4 arranged between the cathode 15 and the anode 3 are formed. The upper end of the baffle plate 4 protrudes above the liquid level, and the lower end of the baffle plate 4 is installed with a predetermined gap from the bottom of the water tank 2, and the gap between the baffle plate 4 and the water tank 2 is the electrolyte. It is comprised so that the distribution | circulation of a solution may be suppressed.
[0046]
Using such a test apparatus, as shown in FIG. 6, a flat plate electrode (in the center) (when the gap between the baffle plate 4 and the water tank 2 is 20 mm, 1 mm, and when the baffle plate 4 is not installed) The current distribution was measured when the cathode 15 was moved in one direction of the water tank 2 (right direction in FIG. 6).
The voltage applied between the electrodes of about 6V, the electrolyte solution was a 0.5% sodium hydroxide solution, the plate electrode 15, area using two kinds of 1 dm ² and 0.5 dm ^2. Further, the moving distance of the plate electrode 15 is represented by a relative value obtained by dividing the actually moved distance by the distance between the electrodes before the movement.
The measurement result of the current distribution is shown in FIG.
[0047]
As shown in FIG. 7, when the baffle plate 4 is not installed, the flat plate is used in both cases where the area is 1 dm ² (indicated by (1) in the figure) and 0.5 dm ² (indicated by ( ² ) in the figure). It can be seen that as the electrode 15 is moved toward one end of the water tank 2, the current value increases greatly.
On the other hand, when the baffle plate 4 is installed, the current value when the plate electrode 15 is moved is substantially constant regardless of whether the gap is 1 mm or 20 mm, and the current distribution in the water tank is uniform. It turns out that it is.
[0048]
Thus, although the reason why the current distribution is constant against Ohm's law is not clear, the provision of flow control means such as a baffle plate also causes some resistance to the passage of ions, and the distance between the electrodes is It is presumed that the resistance acts as a large resistance when the amount of ion passage increases and approaches a small resistance when the distance between the electrodes increases and the passage amount of ions decreases. .
[0049]
Next, test pieces A to I having a three-dimensional shape and an equal surface area as shown in FIG. 8 were installed as cathodes in the center of the test apparatus, and current values were measured for the individual test pieces. The measurement result of the current value when the baffle plate 4 is not installed is shown in FIG. 9, and the measurement result of the current value when the baffle plate 4 is installed so that the gap with the water tank is 20 mm is shown in FIG.
[0050]
When the baffle plate is not installed (graph of FIG. 9), the variation in the current value, that is, (maximum value−minimum value) / average value is about 23%, whereas when the baffle plate is installed (FIG. 9). In the graph (10), it can be seen that the variation in the current value is reduced to about 16%.
[0051]
In this way, the current distribution in the water tank is made uniform by installing a flow restricting means such as a baffle plate between the cathode and the anode, and as a result, fluctuations in the current value due to the three-dimensional shape of the object to be measured. Is greatly reduced.
Therefore, when measuring the surface area of an object to be measured having a complicated three-dimensional shape, the method and apparatus of the present invention can measure the surface area with very high accuracy compared to the conventional method.
[0052]
Next, an embodiment of the plating method according to the present invention will be described.
The apparatus used for the plating method of the present invention is configured in substantially the same manner as the surface area measuring apparatus 1. However, a plating bath containing a predetermined metal ion is used as the electrolyte solution, and an object to be processed is an anode and an electrode is a cathode. It is also possible to use the same metal as the plating metal as the electrode.
[0053]
The specific procedure of the plating method is to immerse a workpiece whose surface area has been measured in advance in a plating bath, adjust the current value so as to obtain a desired current density, and deposit a plating layer by energizing for a desired time. .
The surface area measurement method described above can be suitably used for measuring the surface area of the object to be processed, and the object to be processed whose surface area has been measured is suspended in the rack 5 and immersed in a cleaning tank for cleaning, and then suspended in the rack 5. What is necessary is just to immerse in a plating bath as it is.
[0054]
According to such a plating method, since the current distribution in the plating bath is made uniform and the current density on the surface of the object to be processed becomes substantially constant, even if the object to be processed has a complicated three-dimensional shape. There is an effect that a plating layer having a uniform thickness can be formed.
[0055]
【The invention's effect】
As described above, according to the surface area measuring method and the surface area measuring device according to the present invention, it is possible to accurately measure the surface area of the workpiece.
Moreover, according to the plating method of this invention, a uniform plating layer can be formed on the surface of a to-be-processed object.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a surface area measuring apparatus according to the present invention.
FIG. 2 is a plan view showing one embodiment of a surface area measuring device according to the present invention.
3 is a cross-sectional view taken along line AA in FIG.
FIG. 4 is a partially cutaway perspective view showing another embodiment of the flow restricting means and the electrode.
FIG. 5 is a perspective view of a test apparatus used for confirming the effect of a baffle plate.
6 is a cross-sectional view taken along line BB in FIG.
FIG. 7 is a graph showing measurement results of current distribution.
FIG. 8 is a view showing the shape of a test piece used as an object to be measured.
FIG. 9 is a graph showing measurement results of current values when no baffle plate is installed.
FIG. 10 is a graph showing measurement results when a baffle plate is installed.
FIG. 11 shows an arrangement example of electrodes studied by the present inventors as an improvement plan of a conventional measuring method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Surface area measuring device 2 Water tank 3 Electrode 4 Baffle plate 5 Rack 7 Auxiliary electrode 10 Electrolyte solution 15 Plate electrode

Claims (5)

  In the surface area measurement method of immersing the object to be measured and the electrode in the electrolyte solution, applying a voltage to the object to be measured and the electrode in the electrolyte solution, and measuring the surface area of the object to be measured from the energized state at that time, In the four corners, the electrodes are arranged at two upper and lower positions, respectively, and in the four corners of the water tank, four baffle plates that shield the electrodes from the center of the water tank are arranged, and are elongated between the edge of the baffle plate and the water tank. A method for measuring a surface area, wherein a voltage is applied in a state where resistance is given to the passage of ions by forming a flow path. Surface area measurement method according to claim 1, characterized by arranging the baffle plate as in current distribution immersed the region of the object to be measured is in the range of ± 5%.   A surface area measuring device used for measuring the surface area of an object to be measured from an energized state by applying a voltage to the object to be measured and an electrode immersed in the electrolyte solution, and for accommodating the electrolyte solution And four baffle plates that shield the electrodes from the center of the water tank at the four corners of the water tank, and provide resistance to the passage of ions. Thus, a surface area measuring apparatus characterized in that an elongated channel is formed between the edge of the baffle plate and the water tank. 4. The surface area measuring apparatus according to claim 3 , wherein the baffle plate is provided so that a current distribution in a region where the measurement object is immersed is within a range of ± 5%.   In a plating method in which an object to be processed and an electrode are immersed in an electrolyte solution, a voltage is applied to the object to be processed and the electrode in the electrolyte solution, and metal ions in the electrolyte solution are deposited on the surface of the object to be processed. In the four corners, the electrodes are arranged at two upper and lower positions, respectively, and in the four corners of the water tank, four baffle plates that shield the electrodes from the center of the water tank are arranged, and are elongated between the edge of the baffle plate and the water tank. A plating method characterized in that it is performed in a state where resistance is given to the passage of ions by forming a flow path.

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