JP2019011500A - Partial plating method - Google Patents

Abstract

To provide a technology in which a partial plating of a filamentous member can be simply performed.SOLUTION: A filamentous member 9 that is a to-be-treated material is accommodated in a state of standing position in a cylindrical vessel 1 including a peripheral wall with open holes 13 and a basilar part 4 which is a negative electrode. The cylindrical vessel 1 is arranged in a plating tank, and a plating material is also arranged in the plating tank. To form a plating, a first state in which the filamentous member 9 is in contact with the basilar part 4 and a second state in which the filamentous member 9 is not in contact with the basilar part 4 are alternately repeated in the plating tank.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a technique for partially plating an object using electroplating.

  In electroplating, a metal (plating material) and an object to be plated are placed in a plating tank in which the plating solution is stored, and the positive electrode is connected to the former and the negative electrode is connected to the latter. A potential difference is given between them. Thereby, metal ions eluted from the plating material and / or metal ions in the plating solution are deposited on the surface of the object to be plated, thereby forming a plating film.

  One method of electroplating is called barrel plating. With barrel plating, the object to be plated is placed in a net-like container (barrel) provided with a negative electrode, and this barrel is rotated and vibrated in a plating tank, thereby rolling and mixing the object to be plated and the plating solution. It is a technique for plating, and is often used when many small parts such as screws and springs are to be plated together.

  In barrel plating, a method of rotating a barrel around a horizontal axis, a method of rotating around an axis inclined with respect to the horizontal direction, a method of rotating around a vertical axis, and vibration along a vertical axis There is a method of making it appropriate, and an appropriate method is selected according to the shape of the object to be plated.

  When the object to be plated is an elongated member (linear member), for example, a horizontally long barrel having a rod-shaped negative electrode provided along the longitudinal direction thereof is used. Is laid down and accommodated, and barrel plating is performed by rotating the barrel around a horizontal axis in a plating tank (for example, Patent Document 1).

  However, in this aspect, the linear members may not be sufficiently dispersed in the barrel, or the linear members may be entangled with each other. If it becomes like this, the linear member which is not fully exposed to a plating solution, and the linear member which cannot fully contact an electrode will arise, and it will become poor plating.

  Therefore, a vertically long barrel having a negative electrode provided at the bottom thereof is used, and a large number of linear members are accommodated in the barrel in a standing posture, and the barrel is microvibrated up and down in the plating tank. It has been proposed to perform barrel plating (Patent Document 2).

  In this method, since a group of linear members are accommodated in an upright posture, the linear members are not easily entangled in the barrel, and the barrels are separated by applying a slight vibration. Therefore, each linear member is equally exposed to the plating solution, and can contact the electrode equally.

JP 2000-1798 A Japanese Patent Laid-Open No. 2006-135897

  In some types of parts, a process (so-called partial plating) in which only a part thereof is plated and the other parts are not plated may be required. For example, in the case of an inspection probe pin for inspecting the continuity of a semiconductor device, plating is necessary as a whole, but plating must not be applied to a tip portion to be sharpened.

  When such a partial plating process is performed on a linear member, conventionally, after the entire linear member is plated, the linear member is formed on the distal end portion by immersing the distal end portion of the linear member in a chemical agent. The plating was peeled off. Another method is to form a mask at the end of the linear member before plating the entire linear member, and remove the mask after plating. In any of these methods, a step of peeling the plating and a step of forming / removing the mask are necessary before (or after) the plating, which takes time and cost.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique capable of easily performing partial plating of a linear member.

The method for partially plating a linear member according to the present invention made to solve the above problems is as follows.
(A) a step of setting a linear member as a material to be processed in a standing posture in a cylindrical container having a peripheral wall provided with a through-hole and a bottom as a negative electrode;
(B) arranging the cylindrical container in the plating tank and arranging a plating material in the plating tank;
(C) In the plating tank, a step of alternately and repeatedly forming a first state in which the linear member is in contact with the bottom and a second state in which the linear member is not in contact with the bottom;
Is provided.

  Here, “the linear member is accommodated in an upright posture” is a posture in which only one of both ends of the linear member contacts the bottom, and the linear member is in the axial direction of the cylindrical container. It is preferable that the angle between the angle is 0 ° to 45 °. The “minus electrode” here refers to an electrode to which a potential on the minus side relative to the potential applied to the plating material is applied.

  In the first state, the linear member is electrically connected to the negative electrode at the bottom and is negatively charged, and plating proceeds on the entire linear member. On the other hand, in the second state, since the linear member is separated from the negative electrode, the lower end portion of the linear member close to the negative electrode is positively charged, and dissolution of plating proceeds from the lower end portion (bipolar phenomenon). In the plating tank, the first state and the second state are alternately and repeatedly formed, so that only the vicinity of the lower end of the linear member is not plated but the other portion is plated.

  In order to repeatedly and alternately form the first state and the second state, typically, the cylindrical container may be vibrated or inverted in the axial direction in the plating tank. When the cylindrical container is vibrated in the axial direction, the cylindrical container disposed in the plating tank is in a posture such that the angle between the axial direction and the vertical direction is in the range of 0 ° to 80 °. In particular, the posture is preferably such that the angle is 0 °.

For example, the cylindrical container is set in a posture in which the axial direction thereof is along the vertical direction (that is, a posture in which an angle with respect to the vertical direction is 0 °), and the cylindrical container is vibrated up and down to make the first When the state and the second state are alternately and repeatedly formed, if the downward acceleration of the bottom portion of the cylindrical container (that is, the cylindrical container) is smaller than the downward acceleration of the linear member, the linear member is not separated from the bottom portion. That is, it is necessary to define the vibration frequency and amplitude of the cylindrical container so that the downward acceleration of the cylindrical container is larger than the downward acceleration of the linear member.
For example, when it is assumed that the cylindrical container vibrates with frequency “f” and amplitude “A”, the downward acceleration “a” at the top position is expressed by (Equation 1).
a = A (2πf) ² (Formula 1)
Therefore, the cylindrical container may be vibrated at a frequency “f” and an amplitude “A” that satisfy (Expression 2) (and eventually (Expression 3)). However, “b” is the downward acceleration of the linear member.
a = A (2πf) ² > b (Expression 2)
Af ² > b / (2π) ² (Equation 3)
If the descending acceleration “b” of the linear member is approximated by the acceleration of free fall (gravity acceleration “g”), the frequency “f” and amplitude “A” that satisfy (Equation 4) are allowed. Is done.
Af ² > g / (2π) ² ≒ 0.25 (Equation 4)
According to (Expression 4), for example, when the amplitude “A” is 1 mm, a frequency of about 16 Hz or more is allowed.

  However, in reality, the linear member is disposed in a solution (plating solution) stored in the plating tank, and due to the presence of the plating solution, the downward acceleration “b” of the linear member is the gravitational acceleration “g”. Will be smaller. Specifically, the descending acceleration “b” decreases as the viscosity or density of the plating solution increases. Therefore, the higher the viscosity and density of the plating solution, the wider the range of allowable frequency “f” and amplitude “A”.

  Moreover, the total time (total contact) for which the linear member is in contact with the bottom (minus electrode) during the time (the plating time) in which the process of repeatedly forming the first state and the second state is continued in the plating tank If the proportion of time) is extremely small, plating does not proceed sufficiently. Conversely, if the proportion of the total time during which the linear member is not in contact with the bottom (total non-contact time) in this plating time is extremely small, dissolution of the plating does not proceed sufficiently. In order to achieve partial plating appropriately, the proportion of the total contact time (or total non-contact time) in the plating time is preferably 10% or more, and particularly preferably 30% or more.

  When the cylindrical container is vibrated, the total contact time and the total non-contact time can be adjusted by, for example, the frequency related to the vibration. For example, the frequency may be in the range of 10 Hz to 60 Hz. .

  When the cylindrical container is inverted, the total contact time and the total non-contact time can be adjusted by, for example, the inversion period and the inversion speed. For example, assuming that there is no plating solution, the total contact time and the total non-contact time are made approximately equal by rotating the cylindrical container at a constant angular velocity around a horizontal rotation axis passing through its center. Can do. However, in actuality, the linear member is disposed in the plating solution stored in the plating tank, and the linear member comes into contact with the bottom with respect to the change in the attitude of the cylindrical container due to the presence of the plating solution. It is conceivable that the timing is delayed and the total contact time is shortened. Therefore, it is preferable to provide a time zone in which the cylindrical container is stationary in a posture in which the bottom portion is directly below.

Preferably, in the partial plating method,
A region having a predetermined length from the bottom of the peripheral wall of the cylindrical container is a shielding region in which the through hole is not provided.

By providing the shielding region, the plating solution is unlikely to circulate near the bottom of the cylindrical container. Thereby, in the 1st state, progress of plating to the lower end part neighborhood of a linear member is controlled, and as a result, the length of a non-plating part becomes long. The length of the non-plated portion increases as the length of the shielding region increases. That is, by forming a shielding region having an appropriate length, a non-plated portion having an arbitrary length can be formed.
Even when the shielding region is not provided, a non-plating portion (a portion where plating is not performed) having a certain minimum length which is not zero is formed due to the bipolar phenomenon described above. That is, the shielding region is not an essential configuration for realizing partial plating.

Moreover, the partial plating method which concerns on another aspect is
(A) A linear member is accommodated in an upright position in a cylindrical container having a bottom portion that is an electrode and a peripheral wall provided with a through hole in a portion excluding a region of a predetermined length from the bottom portion. Process,
(B) arranging the cylindrical container in the plating tank and arranging a plating material in the plating tank;
(C) a step of alternately switching between a first application state in which a voltage lower than the plating material is applied to the bottom and a second application state in which a voltage higher than the plating material is applied to the bottom;
Is provided.

In the first application state in which a voltage lower than the plating material is applied to the bottom of the cylindrical container, the plating material is positively charged, and the linear member that is in contact with the bottom of the cylindrical container is negatively charged. As a result, metal ions eluted from the plating material and / or metal ions in the plating solution are deposited on the surface of the linear member, and a plating film is formed. That is, plating proceeds on the entire linear member. However, here, since a through hole is not provided in a region of a predetermined length from the bottom of the peripheral wall of the cylindrical container (it is a shielding region), the plating solution hardly circulates in the vicinity of the bottom. Therefore, the plating thickness formed in the vicinity of the lower end portion of the linear member in the first application state is thinner than other portions.
On the other hand, when the first application state is switched to the second application state, the plating material is negatively charged, and the linear member in contact with the bottom of the cylindrical container is positively charged. As a result, metal ions deposited on the surface of the linear member are eluted, and dissolution of plating proceeds from the entire linear member.
By alternately switching between the first application state and the second application state, only the vicinity of the lower end of the linear member is not plated but the other portion is plated.

  The total time during which the voltage lower than the plating material is applied to the bottom (total low voltage time) is the time during which the process of alternately switching between the first application state and the second application state is continued (plating time). If the proportion is extremely small, plating does not proceed sufficiently. Conversely, if the ratio of the total time (total high voltage time) during which a voltage higher than the plating material is applied to the bottom of the plating time is extremely small, dissolution of the plating does not proceed sufficiently. In order to achieve partial plating appropriately, the proportion of the total low voltage time (or total high voltage time) in the plating time is preferably 10% or more, particularly preferably 30% or more. .

  In said partial plating method, you may disperse | distribute a linear member within a cylindrical container by vibrating a cylindrical container in the axial direction in a plating tank. However, in this case, if the frequency of the cylindrical container is too small, the linear member cannot be sufficiently dispersed, and conversely if it is too large, the time for the linear member to be separated from the bottom electrode becomes long. Thus, the time required for plating becomes uselessly long. Therefore, the frequency of the vibration is preferably set within a range of 10 Hz to 60 Hz.

The present invention is also directed to a partially plated linear member. The linear member is
A plating part formed on one end side, on which a plating layer with a constant thickness is formed,
A non-plated portion on which the plating layer is not formed, formed on the other end side;
A thickness continuously changing portion formed at the boundary between the plating portion and the non-plating portion, and the thickness of the plating layer gradually decreases,
Is provided.

  If the plating layer has a steep cliff shape at the boundary between the plating part and the non-plating part, the corners of the plating layer are easily scraped when the bundled linear members rub against each other. . On the other hand, when a thickness continuously changing portion where the thickness of the plating layer gradually decreases (that is, continuously) at the boundary is formed, the corners of the plating layer are not easily caught, and thus generation of such particles is suppressed. Is done. The continuously changing thickness portion is formed, for example, when partial plating is performed using each of the above partial plating methods. Note that, for example, when the partial plating is formed by performing the step of peeling the plating or the step of forming / removing the mask, the end of the plating layer has a sharp cliff shape.

  According to this structure, partial plating can be performed only by switching the state in a plating tank. That is, partial plating can be easily performed on the linear member without performing the step of peeling the plating and the step of forming / removing the mask before and after the plating.

The figure which shows the structure of a plating apparatus typically. The figure which shows the structure of a cylindrical container typically The figure which shows the flow of the partial plating method which concerns on embodiment. The figure for demonstrating the reaction which arises in each of a 1st state and a 2nd state. The schematic cross section of the linear member plated with the partial plating method concerning an embodiment. The figure which shows the flow of the partial plating method which concerns on a modification. A photograph of a linear member obtained under condition 1. The photograph of the linear member obtained under conditions 2-4. A photograph of a linear member obtained under condition 5. A photograph of a linear member obtained under condition 6. The photograph of the linear member obtained under conditions 7-10.

  Hereinafter, a method for partially plating a linear member according to an embodiment of the present invention will be described with reference to the accompanying drawings. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.

<1. Plating equipment>
First, a plating apparatus used in the partial plating method according to the embodiment will be described with reference to FIG. FIG. 1 is a diagram schematically showing the configuration of the plating apparatus 100.

  The plating apparatus 100 includes a cylindrical container 1, a vibration support 2 that supports and vibrates the cylindrical container 1, a plating tank 3, and electrodes (negative electrodes) connected to terminals extending from a power supply device (not shown). (Bottom part 4) and a plus electrode (plating material 5).

<Cylindrical container 1>
The cylindrical container 1 will be described with reference to FIG. FIG. 2 is a diagram schematically showing the configuration of the cylindrical container 1.
The cylindrical container 1 is a member for accommodating a linear member 9 that is an object to be plated, and includes a container body 11 and a cap 12. Both the container body 11 and the cap 12 are made of an insulating material (for example, acrylic resin).

  The container body 11 is a cylindrical member with one end closed and the other end opened. The length of the container body 11 in the axial direction is sufficiently longer than the linear member 9 that is an object to be plated. Moreover, the diameter (cross-sectional diameter) of the cross section of the container main body 11 is sufficiently smaller than the length of the linear member 9, and the linear member 9 can be accommodated in an upright posture. Here, the standing posture is a posture in which only one of both end portions of the linear member 9 is in contact with the bottom, and preferably, the angle formed by the linear member 9 and the axial direction of the cylindrical container 1 is The posture is in the range of 0 ° to 45 °.

  The cap 12 is a screw-in type cap (so-called screw cap) for closing the open end of the container body 11. A bottom 4 formed of a conductive material is fixed inside the cap 12, and the bottom 4 is an internal space of the cylindrical container 1 when the cap 12 is attached to the open end of the container body 11. Is designed to form the bottom. The bottom 4 is connected to a negative terminal of a power supply device (not shown). That is, the bottom 4 is a negative electrode.

  The peripheral wall of the container body 11 is provided with a plurality of through holes 13 through which the plating solution 30 flows. Here, in a state where the open end of the container body 11 is closed by the cap 12, an area having a predetermined length d from the bottom 4 (that is, the negative electrode) of the cylindrical container 1 is an area where the through hole 13 is not provided (shielding) Region) 14. However, in this embodiment, the shielding area 14 is not an essential element, and the through hole 13 may be provided up to the position of the bottom 4 (that is, the length d of the shielding area 14 may be zero). .

<Vibration support 2>
Refer to FIG. 1 again.
The vibration support tool 2 includes a support tool 21 and a vibration tool 22.

The support 21 holds the vicinity of the upper end of the cylindrical container 1 with the cap 12 facing downward (at least the position above the upper end of the linear member 9 accommodated therein). Any gripping method may be used. For example, the support 21 is formed by a plate-like member provided with a threaded through hole, and an outer peripheral surface near the upper end of the container body 11. Alternatively, the container body 11 may be screwed into the through hole of the support 21 by cutting the screw.
The support tool 21 is disposed above the plating tank 3, and substantially the entire cylindrical container 1 (at least the entire linear member 9 accommodated therein) is stored in the plating tank 3. It supports in the position where it is immersed in the solution (plating solution) 30.
The support tool 21 may support a plurality of cylindrical containers 1 at the same height.

  The vibration tool 22 gives vibration along the axial direction of the cylindrical container 1 to the support tool 21 (and thus the cylindrical container 1 supported by the vibration tool 22). When the cylindrical container 1 is vibrated in the axial direction, the support tool 21 is configured such that the angle between the axial direction of the cylindrical container 1 and the vertical direction in the plating tank 3 is in the range of 0 ° to 80 °. It is preferable to support in a posture, and in particular, it is preferable to support in a posture in which the axial direction of the cylindrical container 1 is along the vertical direction (that is, a posture in which the angle is 0 °) (shown in FIG. 1). State). When the cylindrical container 1 is in such a posture that the angle between the axial direction of the cylindrical container 1 and the vertical direction is 0 °, the vibrating tool gives vertical vibration to the support tool 21. The vibration tool 22 can form a vibration having a designated frequency and a designated amplitude, and specifically includes, for example, a motor whose rotation speed is numerically controlled by an inverter circuit or the like.

<Electrode>
As described above, the negative terminal of the power supply device is connected to the bottom 4 of the cylindrical container 1. That is, the bottom part 4 of the cylindrical container 1 forms a negative electrode. On the other hand, the positive terminal of the power supply device is connected to a plating material 5 which is a metal (for example, a metal to be used as a plating film) to be an anode material. That is, the plating material 5 forms a positive electrode. The plating material 5 is supported at a position (preferably at a position approximately the same height as the cylindrical container 1) where at least a part of the plating material 5 is immersed in the plating solution 30 stored in the plating tank 3. In the example of the figure, two plating materials 5 are provided, and the two plating materials 5 are arranged so as to sandwich the cylindrical container 1. But the number of the plating materials 5 may be one, and may be three or more.

<2. Partial plating method>
The partial plating method according to the embodiment will be described with reference to FIGS. 3 and 4 in addition to FIGS. FIG. 3 is a diagram showing the flow of the method. FIG. 4 is a diagram for explaining reactions that occur in each of a first state and a second state described later.

  Step S1: First, it is assumed that one or a plurality of linear members 9 are accommodated in a standing posture in the cylindrical container 1. Specifically, a plurality of linear members 9 are inserted from the opening of the container main body 11, and the opening is closed with the cap 12 (FIG. 2B).

  Step S2: Subsequently, the cylindrical container 1 in which the linear member 9 is accommodated is supported by the support 21 with the cap 12 facing downward, and the cylindrical container 1 is in a predetermined position in the plating tank 3. It is assumed that it is placed in Similarly, the plating material 5 is placed at a predetermined position in the plating tank 3. By storing a predetermined solution (electrolytic solution that becomes the plating solution 30) in the plating tank 3, almost the entire cylindrical container 1 and at least a part of the plating material 5 are immersed in the plating solution 30. It becomes a state.

Step S3: Subsequently, the power supply device (not shown) starts applying a voltage to the bottom portion 4 and the plating material 5. However, the lower part 4 connected to the negative terminal is given a lower potential (minus side) than the plating material 5 connected to the positive terminal. As described above, the bottom part 4 forms a negative electrode, The plating material 5 forms a positive electrode.
Further, the vibration tool 22 vibrates the support tool 21 (and thus the cylindrical container 1 supported by the support tool 21) in the axial direction of the cylindrical container 1.

  Here, by appropriately setting each parameter when vibrating the cylindrical container 1 (specifically, for example, the frequency and the amplitude are set to values satisfying the above (Equation 3)). The linear member 9 in the cylindrical container 1 vibrated in the axial direction is in contact with the bottom 4 of the cylindrical container 1 (FIG. 4A), and the linear member 9 The second state (FIG. 4 (b)) in which no contact with the bottom 4 is alternately and repeatedly formed. In FIG. 4, only one linear member 9 is shown. However, a plurality of linear members 9 may be accommodated in the cylindrical container 1, and in this case, each linear member 9 is The timing of contacting / separating with the bottom 4 is not always the same.

In the first state, the linear member 9 is electrically connected to the negative electrode, which is the bottom 4 of the cylindrical container 1, and is negatively charged, and the entire linear member 9 is plated. However, in the case where the cylindrical container 1 is provided with the shielding region 14, the plating solution 30 is unlikely to circulate in the vicinity of the bottom 4 of the cylindrical container 1, so that plating is performed on the vicinity of the lower end of the linear member 9 in the first state. Progress is suppressed. As a result, the plating layer is formed only thinner near the lower end than the other portions.
On the other hand, in the second state, since the linear member 9 is separated from the negative electrode that is the bottom portion 4, the lower end portion of the linear member 9 that is close to the negative electrode is positively charged, and dissolution of plating proceeds from the lower end portion. Yes (bipolar phenomenon). In the plating tank 3, the first state and the second state are alternately and repeatedly formed over a predetermined time, so that only the lower end portion of the linear member 9 is not plated but the other portion is plated. A state is formed.

  The total time during which the process of repeatedly forming the first state and the second state in the plating tank 3 (plating time) is in contact with the bottom 4 (minus electrode) (total time) If the proportion of the contact time) is extremely small, the plating does not proceed sufficiently. Conversely, if the proportion of the total time during which the linear member 9 is not in contact with the bottom portion 4 (total non-contact time) in this plating time is extremely small, the dissolution of the plating does not proceed sufficiently. In order to achieve partial plating appropriately, the proportion of the total contact time (or total non-contact time) in the plating time is preferably 10% or more, and particularly preferably 30% or more. The total contact time and the total non-contact time can be adjusted by, for example, the frequency related to vibration, and as an example, the frequency may be in the range of 10 Hz to 60 Hz.

  In addition, when the some linear member 9 is accommodated in the cylindrical container 1, when the cylindrical container 1 is vibrated to the axial direction, this several linear member 9 will be in the state which mutually separated. Therefore, all the linear members 9 are uniformly exposed to the plating solution, and variations in plating thickness between the linear members 9 are less likely to occur.

  Step S4: When a predetermined time has elapsed since the start of Step S3, application of voltage to the bottom 4 and the plating material 5 is stopped. Moreover, the vibration of the support tool 21 (and the cylindrical container 1 supported by the support tool 21) is stopped. Thereafter, the cylindrical container 1 is pulled up from the plating tank 3, and the linear member 9 is taken out from the cylindrical container 1.

<3. Partially plated linear member 9>
FIG. 5 shows a schematic cross-sectional view of the linear member 9 plated by the partial plating method according to the embodiment.
As shown here, in the linear member 9 plated by the above partial plating method, a portion (plated portion) 901 in which a plating layer having a constant thickness is formed has a plating layer formed on one end side. An unfinished portion (non-plated portion) 902 is formed on the other end side, and a portion (thickness continuously changing portion) 903 where the thickness of the plating layer gradually decreases is formed at the boundary between these portions 901 and 902. It will be formed.

  For example, when partial plating is formed by performing a step of peeling plating and a step of forming / removing a mask before and after plating, a cliff shape in which the plating layer stands up at the boundary between the plated portion 901 and the non-plated portion 902 Become. In this case, when the bundled linear members 9 rub against each other, the corner portions of the plating layer are scraped and particles are easily generated. On the other hand, as described above, when the thickness continuous change portion 903 where the thickness of the plating layer gradually decreases at the boundary is formed, the corner of the plating layer is not easily caught, and thus generation of such particles is suppressed. The

  The length of the non-plated portion 902 corresponds to the length d of the shielding region 14 provided in the cylindrical container 1. That is, as the length d of the shielding region 14 increases, the length of the non-plated portion 902 increases. Therefore, a non-plated portion 902 having a necessary length can be obtained by appropriately adjusting the length d. Even when the shielding region 14 is not provided (when the length d is zero), the non-plated portion 902 having a certain minimum length that is not zero is formed. That is, the shielding region 14 is not an essential configuration for realizing partial plating.

<4. Modification>
<4-1 First Modification>
In the above-described embodiment, the first state and the second state are formed by vibrating the cylindrical container 1, but the cylindrical container 1 is reversed (that is, rotated 180 ° around a horizontal axis). ), The first state and the second state may be formed.

  In this case, the total contact time and the total non-contact time can be adjusted by, for example, the inversion period and the inversion speed. For example, assuming that the plating solution 30 is not present, the total contact time and the total non-contact time are approximately equal by rotating the cylindrical container 1 at a constant angular velocity around a horizontal rotation axis passing through the center thereof. can do. However, in actuality, the linear member 9 is disposed in the plating solution 30 stored in the plating tank 3, and the linear member with respect to the change in the attitude of the cylindrical container 1 due to the presence of the plating solution 30. It is considered that the timing at which 9 contacts the bottom 4 is delayed and the total contact time is shortened. Therefore, it is preferable to provide a time zone in which the cylindrical container 1 is stationary in a posture in which the bottom portion 4 is directly below.

<4-2 Second Modification>
The step S3 according to the above embodiment may be performed instead of the next step S3a (FIG. 6).
Step S3a: Application of a voltage to the bottom 4 and the plating material 5 is started from a power supply device (not shown). At this time, a first application state in which a voltage lower than that of the plating material 5 is applied to the bottom portion 4 and a second application state in which a voltage higher than that of the plating material 5 is applied to the bottom portion 4 are alternately switched. Typically, the polarity of the voltage applied to the bottom 4 and the plating material 5 is reversed at a predetermined period.

In the first application state, the plating material 5 is positively charged, and the linear member 9 in contact with the bottom 4 of the cylindrical container 1 is negatively charged. As a result, metal ions eluted from the plating material 5 and / or metal ions in the plating solution are deposited on the surface of the linear member 9 to form a plating film. That is, plating proceeds on the entire linear member 9. However, in this modified example, it is assumed that the cylindrical container 1 is always provided with the shielding region 14. That is, here, since the through hole 13 is not provided in a region having a predetermined length from the bottom of the cylindrical container 1 (the shielding region 14 is provided), the plating solution 30 is unlikely to circulate in the vicinity of the bottom 4. . Therefore, the plating thickness in the vicinity of the lower end portion of the linear member 9 in the first application state is thinner than other portions.
On the other hand, when the first application state is switched to the second application state, the plating material 5 is negatively charged, and the linear member 9 in contact with the bottom 4 of the cylindrical container 1 is positively charged. As a result, metal ions deposited on the surface of the linear member 9 are eluted, and dissolution of plating proceeds from the entire linear member 9.
Therefore, by alternately switching between the first application state and the second application state, only the vicinity of the lower end of the linear member 9 is not plated but the other portion is plated.

  Total time (total low voltage time) in which a voltage lower than that of the plating material 5 is applied to the bottom 4 during the time (plating time) in which the process of alternately switching between the first application state and the second application state is continued. If the proportion of) is extremely small, plating does not proceed sufficiently. Conversely, if the proportion of the total time (total high voltage time) during which a voltage higher than that of the plating material 5 is applied to the bottom 4 in the plating time is extremely small, the dissolution of the plating does not proceed sufficiently. . In order to achieve partial plating appropriately, the proportion of the total low voltage time (or total high voltage time) in the plating time is preferably 10% or more, particularly preferably 30% or more. .

  In the second modification, the linear member 9 may be separated in the cylindrical container 1 by vibrating the cylindrical container 1 in the axial direction in the plating tank 3. However, in this case, if the frequency of the cylindrical container 1 is too small, the linear member 9 cannot be sufficiently dispersed, and conversely, if the frequency is too large, the linear member 9 is separated from the bottom 4 of the cylindrical container 1. The time for separating becomes longer, and the time required for plating becomes uselessly longer. Therefore, the frequency of the vibration is preferably set within a range of 10 Hz to 60 Hz.

<5. Example>
Example 1
The partial plating method according to the above embodiment was performed under the following conditions (condition 1).
i. Linear member 9 to be plated
Cross-sectional diameter: 127 μm, length: 101.6 mm, forming material: tungsten, number accommodated in one cylindrical container 1: 2600 (however, the four cylindrical containers 1 are supported by the support 21, Four cylindrical containers 1 (namely, 10400 linear members 9) were processed simultaneously.)
ii. Shape of cylindrical container 1 Inner diameter: 12 mm, length: about 140 mm, length d of shielding area 14: 16 mm
iii. Plating conditions Plating material: Nickel, bottom 4 forming material: SUS, current: 8A, voltage: 4-8V, plating time: 20 minutes
vi. Vibration conditions Frequency: 34 Hz, amplitude: 1 to 2 mm, vibration direction: vertical direction (that is, in this case, in the plating tank 3, the angle between the axial direction of the cylindrical container 1 and the vertical direction is 0 °. It is said that attitude)

FIG. 7 shows a photograph of the linear member 9 obtained under the condition 1.
As is clear from this figure, the linear member 9 is formed with a plated portion 901 where a nickel plated layer is formed and a non-plated portion 902 where a plated layer is not formed. The length of the non-plated portion 902 was about 13 mm. Although not appearing in the photograph, when the boundary between the plated portion 901 and the non-plated portion 902 was observed using a magnifying glass, it was confirmed that a continuously changing thickness portion 903 was formed.

(Example 2)
The linear member 9 was plated by the partial plating method according to the above embodiment under the same conditions as the condition 1 except that the length d of the shielding region 14 was different (conditions 2 to 4). In condition 2, the length d of the shielding area 14 was 10 mm, in condition 3, the length d of the shielding area 14 was 20 mm, and in condition 4, the length d of the shielding area 14 was 43 mm.

FIG. 8 shows a photograph of the linear member 9 obtained under conditions 2 to 4.
In condition 2, the length of the non-plated portion 902 was about 9 mm. Under condition 3, the length of the non-plated portion 902 was about 18 mm. In condition 4, the length of the non-plated portion was about 35 mm to 37 mm. Further, as described above, under condition 1 (the length d of the shielding region 14 is 16 mm), the length of the non-plated portion 902 is about 13 mm.
Thus, it was found that the length of the non-plated portion 902 increases as the length d of the shielding region 14 increases. Therefore, a non-plated portion 902 having a required length can be obtained by appropriately adjusting the length d.
In addition, when the length d of the shielding region 14 was set to zero, the length of the non-plated portion 902 was 2 to 3 mm. That is, even when the shielding region 14 is not provided, partial plating is realized.

(Example 3)
The plating material was copper and the current was 1.5A. In addition, one cylindrical container 1 was supported on the support 21 and one cylindrical container 1 (that is, 2600 linear members 9) was processed at the same time. Otherwise, the linear member 9 was plated by the partial plating method according to the above embodiment as the same condition as the condition 1 (condition 5).
FIG. 9 shows a photograph of the linear member 9 obtained under the condition 5.
As is clear from this figure, the linear member 9 is formed with a plated portion 901 in which a copper plating layer is formed and a non-plated portion 902 in which no plating layer is formed. It was also confirmed that a continuously changing thickness portion 903 was formed at the boundary between these portions 901 and 902.
Therefore, it was found that the partial plating method according to the above embodiment is effective even when the plating material is copper.

(Example 4)
The linear member 9 was plated by the partial plating method according to the above embodiment under the same conditions as the condition 5 except that the plating material was silver (condition 6).
FIG. 10 shows a photograph of the linear member 9 obtained under the condition 6.
As is clear from this figure, the linear member 9 is formed with a plated portion 901 where the silver plating layer is formed and a non-plated portion 902 where the plating layer is not formed. It was also confirmed that a continuously changing thickness portion 903 was formed at the boundary between these portions 901 and 902.
Therefore, it was found that the partial plating method according to the above embodiment is effective even when the plating material is silver.

(Example 5)
The linear member 9 was plated by the partial plating method according to the above embodiment under the same conditions as the condition 1 except that the frequencies were different (conditions 7 to 10). In condition 7, the frequency was 32 Hz, in condition 8 the frequency was 35 Hz, in condition 9 the frequency was 37 Hz, and in condition 10 the frequency was 40 Hz.

FIG. 11 shows a photograph of the linear member 9 obtained under conditions 7 to 10.
As shown in this figure, the width of the black portion (nickel oxidized portion) appearing between the plated portion 901 and the non-plated portion 902 becomes narrower in the order of condition 7 → condition 8 → condition 9 → condition 10. I understood. That is, it was found that the appearance of the partially plated linear member 1 can be changed by changing the frequency. However, this black portion does not impair the quality of the plating state, and the presence of such a black portion does not deteriorate the quality of the plated product.

(Other examples)
When plating of the linear member 9 was performed by the partial plating method according to the above embodiment under the condition 1 where the plating time was different, the longer the plating time, the greater the thickness of the plating layer formed on the linear member 9. Increased. Further, even when the plating time was changed, the length of the non-plated portion 902 was hardly changed.

  When the linear member 9 is plated by the partial plating method according to the above embodiment assuming that the current value is different in the condition 1, the larger the current value is, the larger the thickness of the plating layer formed on the linear member 9 is. Increased. Further, even when the current value was changed by a minute amount (about 1 to 2 A), the length of the non-plated portion 902 was hardly changed. For example, when the current value was increased to twice (16 A), the non-plating portion 902 was not plated. The length of the portion 902 has increased. In addition, when the current was increased by about twice or more, the appearance changed such that the width of the black portion was widened or the black portion was darkened. Furthermore, it has been found that when the current value is increased by about twice or more, foreign matter (foreign matter derived from the metal particles in the plating material 5 or the plating solution 30) is likely to adhere to the non-plated portion 902.

  In condition 1, it was confirmed that the linear member 9 having various lengths and thicknesses can be partially plated by appropriately adjusting the plating time, current, frequency, and the like. As an example, the length is 76.2 mm or 101.6 mm, and the cross-sectional diameter is 0.051 mm, 0.350 mm, 0.076 mm, 0.090 mm, 0.100 mm, 0.110 mm, 0.127 mm, 0.150 mm, 0.180 mm, 0.200 mm, It was confirmed that partial plating was performed on each linear member 9 of 0.250 mm or 0.300 mm.

DESCRIPTION OF SYMBOLS 100 ... Plating apparatus 1 ... Cylindrical container 11 ... Container main body 12 ... Cap 13 ... Through-hole 14 ... Shielding region 2 ... Vibration support tool 21 ... Support tool 22 ... Vibration tool 3 ... Plating tank 30 ... Plating solution 4 ... Bottom part 5 ... Plating material 9 ... Linear member 901 ... Plating part 902 ... Non-plating part 903 ... Continuous change part

Claims (4)

(A) a step of setting a linear member as a material to be processed in a standing posture in a cylindrical container having a peripheral wall provided with a through-hole and a bottom as a negative electrode;
(B) arranging the cylindrical container in the plating tank and arranging a plating material in the plating tank;
(C) In the plating tank, a step of alternately and repeatedly forming a first state in which the linear member is in contact with the bottom and a second state in which the linear member is not in contact with the bottom;
A method for partially plating a linear member. A region of a predetermined length from the bottom of the peripheral wall of the cylindrical container is a shielding region in which the through hole is not provided.
The method for partially plating a linear member according to claim 1. (A) A linear member is accommodated in an upright position in a cylindrical container having a bottom portion that is an electrode and a peripheral wall provided with a through hole in a portion excluding a region of a predetermined length from the bottom portion. Process,
(B) arranging the cylindrical container in the plating tank and arranging a plating material in the plating tank;
(C) a step of alternately switching between a first application state in which a voltage lower than the plating material is applied to the bottom and a second application state in which a voltage higher than the plating material is applied to the bottom;
A method for partially plating a linear member. A plating part formed on one end side, on which a plating layer with a constant thickness is formed,
A non-plated portion on which the plating layer is not formed, formed on the other end side;
A thickness continuously changing portion formed at the boundary between the plating portion and the non-plating portion, and the thickness of the plating layer gradually decreases,
A linear member.