JPS604278B2 - electroplating method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention uses an electroplating method in which the longitudinal cross-sectional shape of the plated layer changes at an arbitrary continuous angle of inclination with respect to the surface of the target object to be plated (hereinafter referred to as this). It's called taper metal.

), it is related to a new electroplating method developed to obtain the same thickness as possible, and the development and industrial application of conventional electroplating techniques, which aim to average the thickness of the plating layer as much as possible and make it as uniform as possible. This plating method was developed with the aim of finding new industrial application fields for electroplating by developing and providing a new plating material called taper plating, which is completely different from other fields. As there is a technical term such as "uniform electrodeposition" in the terminology related to plating, conventional plating has the concept of having a uniform thickness on average.

At the same time, in the field of plating technology and its application, technological development has been carried out to obtain as uniform a plating thickness and an average plating thickness distribution as possible, and the development of its applications has been studied. However, contrary to the direction of conventional technology and application development as described above, the present inventor considered changing the plating thickness arbitrarily and attempted to develop a technology for controlling this with high precision.

That is, the present inventor believes that if highly accurate taper plating can be performed in the currently used plating application field, as shown in 1 and 2 described below as examples, We believe that the industrial value of tapered plating is that it is extremely effective for each purpose, and is also superior in terms of cost, compared to conventional plating with a uniform thickness. It is. Specific examples are listed below. [11] Application as a plating thickness standard plate As is well known, in the plating industry, measuring instruments are widely used to measure plating thickness by various methods, both destructive and non-destructive.

In order to always use these devices for measuring plating thickness in a normal condition, a plating thickness standard board is prepared by plating a metal plate to a known thickness. It is used when measuring the plating thickness of an unknown object to be inspected to confirm that the measuring equipment used functions and indicates the plating thickness according to the plating thickness display value of this plating thickness standard plate. When a wrong numerical value is indicated, the error is used to correct the measuring equipment. Now here,
Conventional standard plated plates are made by plating the surface of a single metal plate as uniformly as possible to create a plated thickness standard plate.

We also offer a variety of standard plated plates depending on the type and thickness of the plating. In other words, when correcting a plating thickness measuring device, the standard plating plate used for the correction is:
This is because it is desirable to calibrate the equipment by using a plate whose thickness is as close as possible to the plating thickness of the object to be actually measured. For example, if the measurement of the plating thickness of an object to be inspected is expected to be approximately 100 microns, if the measurement of the plating thickness of the equipment used is performed using a standard plating plate of several microns, even if the warp correction is performed correctly. Needless to say, there is a risk that the measurement results will contain a large error compared to the case where a standard plating plate of 100 microns is used for the measurement. On the other hand, when measuring the plating thickness of an object to be inspected, which is expected to have a plating thickness of several microns, when using a standard plating plate of 100 microns, the previous example Although Z has no problem with thickness measurement accuracy, he ends up spending tens of times as much time correcting the measuring equipment as it takes to actually measure the plating thickness, which is extremely uneconomical in terms of time and requires unnecessary work. I have to say that the accuracy is the same. In view of the above-mentioned current situation, the present inventor devised a method of producing a standard plated thick plate using tapered plating. In other words, it is a test piece with a plating thickness ranging from several microns to several hundred microns on one standard plating plate, and if taper plating can be performed with high precision, most of the current plated thickness can be achieved with this single standard plating plate. It is easy to imagine that it is possible to perform the optimum measurement in each case with respect to the equipment correction when measuring all types of plating thickness.

(2- Application as penetrant test specimen) As a method for detecting minute defects, such as cracks and pinholes, that may exist on the surface of inspected objects such as aircraft parts in non-destructive testing methods. Penetrant testing is generally used.

The penetrating deep flaw inspection method uses an oily liquid called a penetrating liquid usually colored with a red dye or a yellow fluorescent dye inside the inspected object, inside minute surface defects that cannot be detected with the naked eye. By applying it to the surface, the penetrating liquid penetrates into the defects on the surface of the object to be inspected. After that, the penetrating liquid remaining on the surface is wiped off with a cloth etc.
After that, a liquid made by dispersing usually white inorganic fine powder called a developer in a volatile organic solvent is applied, and as the solvent evaporates and scatters, residual penetration inside the defects that is formed on the white fine powder left behind is removed. This method uses the smudge pattern of the liquid to magnify minute defects that were initially impossible to detect with the naked eye.

It goes without saying that the accuracy of defect detection in this penetrant test is largely dependent on the quality of the performance of the penetrant liquid described above. Now, a conventional method for determining the performance of a penetrating liquid will be explained.

At present, several types of test specimens have been proposed for the purpose of determining the performance of the permeate and also for maintaining and controlling its performance during storage.

For example, the penetrant inspection test piece (hereinafter referred to as a known test piece) described in "Utility Model Publication 14633/1984" is made by plating the surface of a copper plate with a uniform thickness. An artificial defect is created by bending the material and breaking the plating. According to this method, it is possible to create artificial defects of any depth with good reproducibility, so it is widely used as a penetrating deep flaw inspection test piece for performance testing of penetrating liquids, quality control, etc. However, since this known test piece is one in which the plating thickness is uniformly plated on a single metal slope, several types of test pieces are prepared depending on the required defect depth, that is, the plating thickness. However, in practice, only several types from 10 microns to 50 microns are manufactured and used at 10 micron intervals.

However, with the development and sophistication of industry in recent years, a more advanced quality control system than before is now required.
The performance of penetrating deep wound agents has been greatly improved compared to conventional ones, and it has become impossible to judge the superiority or inferiority of their performance using several types of known test pieces. In order to deal with this current situation, it is possible to make dozens of known test pieces at intervals of several microns, but in reality, the technology to control the plating thickness uniformly is limited to the desired plating thickness. It is barely possible to secure a soil content of 10% or less, and making test pieces at intervals of several microns is currently meaningless.

For example, if we assume that test pieces are made at 5 micron intervals, a test piece with a scratch depth of 45 microns and a test piece with a scratch depth of 50 microns.
Comparing the micron test pieces, the plating thickness accuracy is ±10% of the nominal dimension, so the test piece with a scratch depth of 45 microns has an actual scratch depth range of 40.5 microns to 49.5 microns. In the range of 5 microns. On the other hand, a test piece with a scratch depth of 50 microns was
This will range from 5.0 microns to 55.0 microns.

Therefore, both test pieces had a common scratch depth range between 45.0 microns and 49.5 microns.
Even though the flaw depth is classified as 45 microns and 50 microns, if both are within this range, it is possible that the results of the flaw detection test will be exactly the same. . Furthermore, depending on the case, the nominal dimensions of the two parts may be completely opposite in size, so there is Z. In light of the current state of plating technology, it is appropriate to prepare several types of known test pieces for practical use at 10 micron intervals. However, as mentioned above, the demand from various industries for penetrant testing methods in recent years is that the performance of penetrant testing agents can be determined at least at a single Z level of several microns in test specimens, and that it is also possible to use penetrant testing methods for purposes such as deep flaw process management. There is a strong desire to develop something with performance that can also be used in other applications. In view of the above-mentioned current situation, the present inventor devised a test piece for penetrating deep damage inspection using tapered plating.

In other words, it takes advantage of the advantages of the known test pieces, which are made by applying metals such as nickel or chromium to the surface of a yellow steel plate, and then artificially breaking this plating layer, while also creating a test piece that could not be created using conventional plating techniques. This is because the taper plating technology of the invention is applied to this. The penetrant test specimen obtained by taper plating has a plating thickness of 1 micron on one side and 50 micron on the other side, in other words, a scratch depth of 1 micron on the other side. Artificial defects of up to 50 microns are applied with high accuracy and proportional variation along the length of the specimen. For this reason, the depth of each crack on the test piece varies continuously from 1 micron to 50 microns, and when used for a performance test of penetrating liquid, the depth of each crack on the test piece varies continuously from 1 micron to 50 microns. Previously, it was only possible to judge the defect detection ability in units of 7 microns, but now it is possible to judge the defect detection ability very strictly, such as 7 microns, and judge its superiority or inferiority accurately and objectively. You can easily imagine what will happen.
The present inventor has focused on the fact that, as is clear from the above two items, the characteristics and application value of tapered plating are superior to conventional plating with a uniform thickness. However, as a result of conducting various experiments regarding the implementation of the taper plating method, the method of the present invention was completed. Next, the configuration of the present invention will be explained using the drawings.

The drawing is a diagram illustrating the arrangement of electrodes, etc. in the plating bath in the taper plating method of the present invention. As shown, an anode A is placed at one end of the plating tank 1, a cathode B, which is an object to be plated, is placed at the other end via a cathode pick C, and a conductive shielding plate D is placed close to the cathode B. and place it.

Then, the shielding plate D and the cathode B, which is the object to be plated, are connected with a coated copper wire 2 of an appropriate thickness so that a part of the cathode current flows through the shielding plate D during plating work, and further, the shielding plate D is moved in any direction such as up and down, right and left, parallel to the surface of the cathode B, which is the material to be plated, during the plating operation, that is, while being energized. However, in some cases, the shielding plate may be fixed and the object to be plated may be moved. At this time, the movement distance, movement speed, and number of movements of the shielding plate (on the other hand, the same movement or several times of reciprocating movement) are determined arbitrarily, but the shape of the napper applied to the plating layer is adjusted to the longitudinal cross-sectional shape of the plating layer. In order to maintain a straight line at a constant angle, the moving distance and moving speed of the shielding plate must of course be changed, and the current value per unit area flowing through the cathode including the shielding plate, that is, the cathode current density (unit: A)
/d) must be kept constant during plating work. However, if the type of taper given to the plating bath is to obtain a constant proportional curve shape or an irregular curve 0 shape in the vertical cross-sectional shape of the plating layer, then the shielding Any one or all of the moving distance, moving speed, and cathode current density of the plate may be appropriately changed at a constant rate or irregularly to meet the above requirements. Next, a specific example for carrying out taper plating will be given, focusing on the above-mentioned shielding plate that enables taper plating in the method of the present invention, and its structure and function will be described in detail.

First, type 0 of plating that can be performed by the method of the present invention is the type of metal that can be electroplated normally, such as single metals such as copper, iron, nickel, cobalt, and chromium, and nickel-cobalt and iron-nickel. , or copper-zinc (minodo)
All types of plating, such as alloy plating consisting of multiple metal compositions, are possible, and the anode material used, the composition of the plating solution, and the plating conditions (solution temperature, pH of the solution, current density, etc.) are usually variable. The materials and standard plating conditions used for plating work can be applied as is. For example, when taper plating nickel, use a commercially available nickel plate, key, etc. as the anode as the electrode.
The plating solution is nickel sulfate (NiS04) in 1 cup of water.
Group 20) 30 female, nickel chloride NiC12 skin 20) 4
5g, boric acid (Japanese 3B03) 30-37. You can use the wattage whose standard composition is Heron as is.

In addition, the plating conditions in this case are that the liquid temperature is 3.0~7.
1°C, FH2.0-5.2, current density 1-6. This can be done in each range of $/d. Next, regarding the conductive shielding plate that forms the basis of the method of the present invention, most ordinary metal plates that are good conductors of electricity can be used; however, for the metal to be plated, It is desirable to use the same metal for the shield plate as the metal to be plated.

This is because if the metal of the shielding plate used for the plating anode and cathode metal is an electrochemically much less base metal, in other words, a metal with a low standard potential value, the shielding plate metal may be present in the plating solution. This is because there is a risk that the particles will dissolve and become foreign ions, which will disturb normal plating conditions. Next, regarding the shape of the shielding plate, its size relative to the original cathode that is the object to be plated, and its setting position, the shape differs depending on the shape of the original cathode that is the object to be plated. When the material to be plated has a flat plate-like shape, as in the embodiment described later, the shielding plate may also be a flat plate-like material. For example, if the material to be plated has a cylindrical shape like a piston and the entire outer circumference is to be 7-percent plated, a cylindrical plate that can completely cover the outer circumference of the cylindrical object to be plated is used. It is sufficient to use a shaped shielding plate. Next, regarding the size of the shield plate, it can reliably shield the target taper plating range on the cathode surface, which is the object to be plated, from the plating current flowing from the anode. As long as it's big enough, it's fine.

Also, as is clear from the purpose of the shielding plate, the setting position of the shielding plate, that is, the distance between the shielding plate and the cathode of the main holder which is the object to be plated facing it, should be set as close as possible. Needless to say, it is desirable to set it to . In the taper plating according to the present invention, part of the cathode current is passed through the shielding plate configured as described above during the plating operation,
Furthermore, the shielding plate is moved vertically, horizontally, etc. in the direction of the taper applied to the surface of the plated material. In order for the shielding plate to function in this way, the original cathode, which is the shielding plate and the plating material, must be moved. At one point, or at several points if necessary, use an electric wire of an appropriate thickness covered with vinyl, etc., so that even if the shielding plate moves during plating, it will not impede the movement of the electric wire, and Must be concatenated by a subsequent method.

Furthermore, various methods can be considered for moving the shielding plate, but the method shown in the drawings, which the present inventor actually tried and succeeded in, can be used. In addition, when moving the shield plate, in order to keep the distance between the shield plate and the material to be plated constant no matter where the shield plate moves, a cathode jig is used to hold the object to be plated. , and a guide jig for fixing the direction of movement of the shielding plate are preferably made in one piece.

Next, the process of performing 7-perme plating using the plating method configured as described above will be explained from the actions and effects produced by the shielding plate.

In addition, in the explanation, the type of taper plating applied to the object to be plated is that the plating layer is regular in its vertical cross-sectional shape.
An example of continuous change will be explained. As is well known, in electroplating, the amount of plating metal deposited on the surface of the object to be plated at the cathode, which is the result of oxidation and reduction reactions in a broad sense, is governed by Farandee's law.

In other words, in electroplating, ``the amount of metal deposited on the cathode is proportional to the amount of electricity required to perform plating, and the amount of electricity required to deposit 1 g of plated metal is related to the type of plated metal. 96,500 clones (C).'' By calculating from this law, for example, in the case of nickel plating, the current efficiency of the cathode can be increased to 100%.
Assuming that, approximately 1 for the electrical quantity IAH during plating
1 g of metallic nickel will be deposited on the cathode. Here, if we calculate this amount of precipitation to the plating thickness per unit area (assuming the specific gravity of nickel is 8.9), we get the electrical quantity IAH
(amp hours) is an average of 12 per cathode area ld
．． 3ヱ thick nickel plating will be deposited. Trowel,
As a result of this development, there are three elements related to the thickness of plating: the amount of electricity used during plating, namely: ■ current value @ time (H), and ■ cathode area (d〆). I understand. In order to obtain normal plating, that is, one in which the thickness of the plating layer is uniform, it is sufficient to keep these three items ■, @, and Q at constant values throughout the plating process. Conversely, in order to change the
When plating any one of the items, it must be changed regularly from beginning to end. Regarding these three items, the present inventor focused on the @ time as a means of making regular changes accurately and easily in actual plating work. The time, ie, the time during which plating is performed on the cathode, is varied regularly from beginning to end from one end of the material to be plated to the other.
However, by changing this element called time, the two remaining items, (i) the current value and (i) the cathode area (d〆), that is, the current density (A/d) remain constant throughout the plating. must be maintained. As a method for regularly changing the plating time described above, the present inventor has proposed the following method during plating work:
In order to completely shield the material to be plated while moving the shield plate at a constant speed, a portion of the cathode current was applied to the conductive shield plate. With this shielding method, even if there is some distance between the original cathode, which is the material to be plated, and the shielding plate, the part of the material to be plated that overlaps with the shielding plate is completely electrically shielded when viewed from the anode direction. .

Since this shielding plate moves at a predetermined speed, the plating time is short on the surface of the object to be plated, so sections where the plating time is longer are created in the direction of movement of the shielding plate, and as a result, the plating time is longer on the surface of the object to be plated. Tapered plating is formed on the surface of an object, with the plating thickness regularly increasing from the part with the smallest plating thickness.・Furthermore, when performing taper plating in the method of the present invention, as mentioned above, it is necessary to keep the current density (A/d) at the cathode constant from beginning to end. By adopting a method of flowing a part of the original cathode current, the increase or decrease in the current flowing through the object to be plated is consumed as is in the shielding plate.
In other words, even if the surface area (d〆) of the original cathode, which is the object to be plated, increases or decreases as the shielding plate moves, the shielding plate itself will at the same time take up the increased or decreased area as another cathode, naturally increasing its surface area. Since this is a supplementary method, the cathode area, that is, the plating current density does not change from beginning to end, and the current value A set at the start of plating does not need to be changed at all. Here too,
If part of the cathode current is not passed through the shielding plate, or if the material is changed to non-conductive plastic etc. for plating, it is inevitable that the current density at the cathode surface will change as described above. Needless to say, this poses a major problem when performing taper plating. Furthermore, in order to avoid this problem, it is almost impossible to control the plating current value by changing it during plating work to follow changes in the area of the plated material, which is almost impossible with the current plating technology. It is.
The electroplating method of the present invention configured as described above theoretically and practically incorporates the idea of a novel form called "taper plating" which did not exist even in the conventional plating terminology. This is a completely new plating method that makes it possible to perform this with high precision, and at the same time, the plating form called "taper plating" has extremely high practical value.

Next, examples of the method of the present invention will be given.

Example 1 A yellow steel plate was plated to obtain tapered nickel plating in which the plating thickness varied regularly at a constant ratio from one end to the end of the plate.

Before plating, first prepare the materials and equipment described below. (A) Plating tank: 1 box-shaped plating tank made of pinyl chloride with an inner diameter of 4 mm vertically, 25 mm wide, and 50 mm deep.Object to be plated: 30 mm long x 15 mm wide x 2 mm thick. Yellow steel plate Anode: Nickel electrode for plating with length 30 arcs x width 15 arcs and thickness IQ cape Shielding plate: Move this shielding plate up and down on a brass plate of length 30 arcs x width 15 arcs x thickness 2 feet. A vinyl chloride-coated electric wire is connected to one end for the purpose of both powering and energizing.

Cathode pick-up tool: It is made to fix both the object to be plated and the shielding plate in the plating tank, and always keep the distance between the two sides at 5 sides, and at the same time pick up the object to be plated to the nuclear plating object through the contact with the object to be plated. A jig with the function of supplying cathode current.Filling liquid:
Nickel sulfate (NiS04, bait 20) 300g/night, nickel chloride (NiC12, fine 20) 45g/day, boric acid (Japanese 3B03) 3 sides/side and as a plating brightener Acuna B-, 20'/side, Acuna B-21 [/Yu (Akuna B- and B-2 are both trade names) plating solution made of 40% lotus bath, and remove any contaminants by common means such as activated carbon and air force dissolution. Next is the plating conditions, p
H4.0, liquid temperature 50 degrees, current density 4A/d, the secondary current value of the power supply is one ship, and the shield plate is moved once from top to bottom, and the speed is one enemy. The speed was set at a constant speed of ribs/minute.

Using the plating equipment and plating conditions as described above, electroplating was performed between three powders using a three-phase full-wave direct current using a silicon rectifier. A bright nickel plating was obtained.

The results of measuring the plating thickness at intervals of 3c in the length direction of the object to be plated using an electrolytic plating thickness measuring device are shown in FIG. 2, and it can be seen that the taper plating is extremely accurate.

Example 2 A yellow steel plate was plated to obtain tapered nickel plating in which the plating thickness varied in a curved shape in its longitudinal cross section.

All of the materials and equipment used for plating were the same as in Example 1 except for the mouth plated object and the second shielding plate, and the plated objects and shielding plates were made of the same materials as in Example 1. I prepared a shape. Next, the plating conditions are pH 4.0, liquid temperature 48°C, cathode current density 4A/
d, that is, the secondary current value of the power supply was one ship, and the shield plate was moved once from the bottom to the top.

The moving speed of the shielding plate is not constant, and the gear ratio of the trout stage variable distance motor is manually adjusted so that the moving speed of the shielding plate becomes gradually farther in the range of 5 side to 35 skin per minute during plating. operated. With the plating equipment and plating conditions as above,
As a result of electroplating for 30 minutes using a three-phase full-wave direct current using a silicon rectifier, glossy nickel plating was obtained on the entire surface of the object except for one end, about 5 togs. The results of measuring the plating thickness at three skin intervals in the length direction of the object to be plated using an electrolytic plating thickness measuring device are shown in Figure 3. By arbitrarily changing the moving speed of the shield plate, It can be seen that taper plating that changes along an arbitrary curve can be obtained.

[Brief explanation of the drawing]

FIG. 1 shows an outline and an example of the electroplating method according to the present invention.
It is a diagram drawn and explained as a model. In the figure, A is an anode, B is a cathode, C is a cathode jig, D is a shielding plate, 1 is a plating bath, 2 is a coated copper wire, 3 is a pulley, 4 is a copper wire, 5 is a reducer, 6 is a continuously variable speed motor. FIGS. 2 and 3 are graphical representations of actual measured values of changes in the plating thickness of taper plating in Examples 1 and 2, respectively. In the figure, A is the plating thickness (unit: microns), the opening is the measurement position of the plating thickness (distance from one end of the plated plate: centimeters), and C is the line connecting the actual values of the plating thickness at each measurement position. This shows the state of change in plating thickness.
Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1 In the electroplating method, a conductive shielding plate configured to allow a part of the plating cathode current to flow is used. An electroplating method characterized by arbitrarily changing the thickness of the plating to be electrodeposited on the object to be plated by arbitrarily changing the shielding part of the shielding plate for the object to be plated. .