JP2014201794A - Electroless plating method and electroless plating apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electroless plating method capable of plating uniformly at high speed without taking out a plating solution to the outside of a plating tank, and to provide an electroless plating apparatus usable preferably for execution thereof.SOLUTION: In the dipped state into an electroless plating solution of a rod-like plating object whose one end is mounted on a revolving shaft 46 in the tilted state at a prescribed angle with respect to the axial direction of the revolving shaft 46 or in the decentered state with respect to the shaft center of the revolving shaft 46, the revolving shaft 46 is rotated, to thereby plate the other end of the plating object, while moving it circularly.

Description

  The present invention relates to an electroless plating method for performing plating while rotating an object to be plated at a high speed in a plating tank, and an electroless plating apparatus suitable for use in the implementation of the electroless plating method.

  The electroless plating method is a plating method that utilizes a reducing action caused by contact between a catalyst on the material surface and a plating solution. Since it is possible to plate an object to be plated made of a non-conductive material, and it is possible to plate a small object to be plated with a relatively uniform film thickness, it is widely used for automobile parts, semiconductor materials, and the like.

  Conventionally, in the electroless plating method, a large number of objects to be plated are suspended on a jig and immersed in a large plating tank to perform plating. However, when this method is used, a large amount of metal ions remains in the plating solution that has reached the end of its life. Therefore, there is a problem that a large loss occurs economically if this metal ion is not recovered. When the metal ion is a noble metal ion such as gold or platinum, the recovery of the metal ion is particularly important.

  On the other hand, a barrel system in which plating is performed by housing an object to be plated in a hexagonal cylindrical porous barrel and gently rotating the barrel in an electroless plating solution is also well known. This method also has the above problem. Furthermore, the objects to be plated collide with each other during plating, and depending on the material of the objects to be plated, there is a problem that the objects to be plated are deformed, broken, or damaged.

  Furthermore, in the case of the above electroless plating method, a large amount of plating solution adhering to the jig, barrel, object to be plated, etc. is taken out of the plating tank after completion of plating, which is uneconomical. This problem is particularly serious when the plating solution is a noble metal-containing plating solution.

  Another problem is that the plating time is long. When performing electroless plating, the plating time is long and requires about 10 hours. However, this time is too long as a plating time for industrial purposes.

As an electroless plating apparatus, for example, Patent Document 1 is cited.
JP 2003-113477 A

  The present invention has been made in view of the above circumstances, and the object thereof is an electroless plating method capable of performing uniform plating at high speed and without taking out a plating solution outside the plating bath, and the method thereof An object is to provide an electroless plating apparatus suitable for use in implementation.

  The present inventors have made various studies in order to achieve the above object. As a result, it is possible to perform electroless plating at a high speed of 1/5 to 1/10 hours compared to the conventional electroless plating time by causing the rod-shaped object to rotate in a predetermined rotational motion in the electroless plating solution. I knew. In addition, a plurality of gears that mesh with each other can be detachably attached to the plating tank, and a drive gear fitted with a motor can be meshed with this gear so that a large number of objects can be electrolessly plated simultaneously with a simple mechanism. I have come to know and have completed the present invention.

  Therefore, the present invention that solves the above problems is described below.

[1] a support frame;
A heating tank fixed to the support frame;
A rack disposed in the heating tank and having a predetermined number of plating tank insertion holes;
A stirring part fixing arm disposed above the plating tank across the plating tank;
A stirring unit mounting means for detachably mounting the stirring unit to the stirring unit fixing arm, and a gear unit including a predetermined number of gears meshing with each other, and the rotating shaft of each gear bends at a predetermined angle. A stirrer connected to a stirrer fixing arm and connected to a plating object mounting adapter or an adapter for mounting a plating object eccentric with the rotating shaft, and the gears are located above the plating tank insertion holes,
A motor having a drive gear meshing with any gear of the stirring unit;
An electroless plating apparatus comprising:

  [2] The rotating shaft of the gear and the adapter for mounting the object to be plated are formed by a cylindrical body communicating with each other, and by attaching one end of the cylindrical object to be plated with the other end closed, The electroless plating apparatus according to [1], wherein the plating solution is supplied into the object to be plated through the communicating cylinder.

  [3] The electroless plating apparatus according to [1], including a vibrator coupled to a support frame.

  [4] The electroless plating apparatus according to [1], wherein the plating tank is formed in a bottomed cylindrical shape.

  [5] The electroless plating apparatus according to [1], wherein the plating solution supplied to the plating tank is an electroless platinum plating solution.

  [6] The electroless plating apparatus according to [1], wherein the object to be plated is formed in a cylindrical shape with the other end closed.

  [7] By rotating the rotating shaft in a state where the rod-shaped object having one end attached to the rotating shaft and inclined at a predetermined angle with respect to the axial direction of the rotating shaft is immersed in the electroless plating solution, An electroless plating method in which plating is performed while circularly moving the other end.

  [8] An object to be plated is obtained by eccentrically aligning the axis of the rotating shaft and the axis of the rod-shaped object to be plated, attaching the object to be rotated to the rotating shaft, and rotating the rotating shaft while immersed in the electroless plating solution. Electroless plating method in which plating is performed while circularly moving the axis of the plate.

  [9] The electroless plating method according to [7] or [8], wherein the rod-shaped object to be plated has a hollow portion whose other end is closed, and plating is performed by injecting an electroless plating solution into the hollow portion.

  [10] The electroless plating method according to [7] or [8], wherein the electroless plating solution is an electroless platinum plating solution.

  [11] The electroless plating method according to [7] or [8], wherein the rotational speed of the rotating shaft is 600 to 3000 times / minute.

  [12] The electroless plating method according to [7], wherein the axis of the object to be plated is inclined by 1 to 40 degrees with respect to the axial direction of the rotary shaft.

  [13] The electroless plating method according to [8], wherein the axis of the rotating shaft and the axis of the object to be plated are eccentric by 0.5 to 30 mm.

  [14] The electroless plating method according to [7] or [8], wherein the metal ions in the plating solution are used up in one plating.

  In the electroless plating method of the present invention, the object to be plated is rotated while being inclined or decentered with respect to the rotation axis, so that the stirring effect is high, the supply of reactants is promoted, and the film thickness is uniform. High plating performance and high plating speed.

  In the electroless plating method of the present invention, since the rod-shaped object to be plated is rotated in the plating solution, the plating tank may be a small-volume cylinder, and the plating solution volume to be used can be reduced. Therefore, this plating method is suitable for electroless plating in which the metal ions in the plating solution are used up in a single plating.

  When this method is applied to precious metal plating, the amount of plating solution may be the minimum necessary amount, and as a result, the amount of waste liquid in the plating tank can be reduced, which is economical. Furthermore, since the plating solution is used up and the plating solution is renewed at every plating, the concentration of reducing agent and noble metal ions in the electroless plating solution is increased, and the plating rate is increased while maintaining the stability of the plating solution. be able to.

  This plating apparatus can avoid unnecessary portions from being plated by pulling portions that do not need to be plated from the plating solution surface. Furthermore, since the present plating apparatus does not use a jig, a plating solution circulation pump, a plating solution stirring blade, or the like, the structure of the device is simplified. Further, since no plating film is formed on these portions, the maintenance of the plating apparatus is facilitated.

  Since the present plating apparatus can integrally attach the stirring unit composed of a plurality of gears to the plating apparatus, the operability is good when plating a plurality of objects to be plated at the same time.

It is a front view which shows an example of the electroless-plating apparatus of this invention. It is a side view which shows an example of the electroless-plating apparatus of this invention. It is a front view which shows an example of the state of the to-be-plated object with which the electroless-plating apparatus of this invention was mounted | worn. It is a front view which shows the other example of the state of the to-be-plated object with which the electroless-plating apparatus of this invention was mounted | worn.

  Hereinafter, with reference to the drawings, an embodiment of the present invention will be described in detail.

  In FIG. 1, 100 is an electroless plating apparatus showing an example of the present invention. Reference numeral 2 denotes a plate-like base, and a stirrer 4 is placed on the base 2. A heating tank 6 is disposed at the top of the stirrer 4 and the inside thereof is filled with a heat medium 8 such as water. The heat medium 8 is stirred by the stirrer 4 and heated by the heater 10 to be maintained at a desired medium temperature. These controls are performed by the control device 12.

  A rack 14 is immersed in the heating medium 8 and inserted into the heating tank 6. The rack 14 has a locking portion 16 at the upper end thereof, and is fixed in the heating bath 6 by locking the locking portion 16 to the upper end of the heating bath 6.

  The rack 14 has a box shape having a bottom plate 18, and has an intermediate plate 20 and an upper plate 22 disposed in parallel with the bottom plate 18. In the middle plate 20 and the upper plate 22, a predetermined number (five in this example) of the middle plate plating tank insertion holes 24 and the upper plate plating tank insertion holes 26 are vertically centered with respect to each other. It is drilled to match.

  Reference numeral 28 denotes a predetermined number (in this example, five) of plating tanks, which are inserted into the plating tank insertion holes 24 and 26 and fixed to the rack 14. The plating tank 28 is made of a bottomed cylindrical synthetic resin and has an external shape similar to that of a test tube used in a chemical experiment.

  Reference numeral 30 denotes a support frame, which is fixed to the base 2 by fixing means (not shown). Above the plating tank 28, a stirring portion fixing arm 32 is attached to the support frame 30 across the plating tank 28. A predetermined number of through holes 34 are also formed in the stirring portion fixing arm 32. The through hole 34 is a hole for inserting a rotating shaft 46 described later. Reference numeral 33 denotes a vibrator attached to the support frame 30.

  Reference numeral 36 denotes an agitation unit, and reference numeral 38 denotes an agitation unit substrate having a U-shaped cross section. The stirring unit substrate 38 is placed on the upper surface of the stirring unit fixing arm 32, and the stirring unit fixing arm 32 is attached to the stirring unit fixing arm 32 with one touch by means of the stirring unit mounting means 40 mounted on both ends in the length direction of the stirring unit substrate 38. It is fixed detachably with.

  Reference numeral 42 denotes a gear portion, which is composed of a predetermined number (in this example, five) of gears 44 that are rotatably attached to the stirring portion substrate 38 with the rotation axis of the gear being vertical. The predetermined number of gears 44 mesh with each other, and the rotation of one gear 44 is transmitted to the remaining gears 44.

  The rotation shaft 46 of each gear 44 is cylindrical as shown in FIG. 3 and is formed of an internal hollow tube, and one end side 48 thereof extends downward in the vertical direction. To one end side 48 of the extended rotating shaft 46, an inclination adapter 50 for mounting a workpiece to be attached is attached at an angle with respect to the axial center direction of the rotating shaft 46, and is connected via an elastic synthetic resin tube 52. Thus, the adapter 50 and one end 56 of the workpiece 54 are connected. Therefore, the workpiece 54 is attached to the rotating shaft 46 with its axis inclined at a predetermined angle with respect to the axis of the rotating shaft 46 of the gear 44.

The inclination angle is preferably 1 to 40 degrees, and more preferably 2 to 10 degrees. When the inclination angle is less than 1 degree, the plating time shortening effect is small. When the inclination angle exceeds 40 degrees, there is no particular problem, but the plating tank becomes large, the dilution rate of the plating solution increases, the consumption rate of platinum ions decreases, and the plating time becomes long and uneconomical.

  Any one of the predetermined number of gears 44 is connected to a drive gear 66 of a drive motor 64 via a connection gear 58 and transmission gears 60 and 62 as shown in FIG. Therefore, by operating the motor 64, the rotation of the motor shaft is shifted and transmitted to all the predetermined number of gears 44.

  Next, the case where the object 54 is electrolessly plated using the electroless plating apparatus 100 will be described.

  First, the plating tank 28 containing the plating solution 60 (FIG. 3) is inserted into the plating tank insertion holes 24 and 26 of the rack 14.

  An object to be plated 54 is attached to the adapter 50 attached to one end side 48 of each gear rotation shaft 46 of the stirring unit 36 removed from the electroless plating apparatus 100 via a synthetic resin tube 52 (FIG. 3). . In the case of this example, the workpiece 54 is a ceramic tube formed in a bottomed cylindrical shape, and a catalyst layer (not shown) is formed in a desired pattern on the outer surface and the inner surface. The stirring portion 36 to which the object 54 is mounted is placed on the stirring portion fixing arm 32. At this time, the object 54 is inserted into the plating tank 28 and meshed with the gear 44. The connected gear 58 meshes with the transmission gear 60. In this state, the stirring unit 36 is fixed to the stirring unit fixing arm 32 by operating the stirring unit mounting means 40.

  Thereafter, the electroless plating solution is supplied to the hollow portion in the object to be plated through the rotation shaft 46 of each gear 44 and the hollow portion in the adapter 50.

  Next, the heating medium 8 in the heating tank 6 is heated to the electroless plating temperature by the heating tank stirrer 4 and the heater 10.

  After the above operation is completed, the motor 64 starts to operate according to an instruction from the control unit 12. The rotation of the rotation shaft of the motor 64 is transmitted from the drive gear 66 to the connection gear 58 while changing the rotation speed with the gears 62 and 60, and finally transmitted to the gear 44 meshing with the connection gear 58. Thereby, all of the predetermined number of gears 44 rotate at the same rotational speed. As a result, the other end 70 of the workpiece 54, which is inclined at a predetermined angle with respect to the axial direction of the rotary shaft 46 of the gear and has one end attached to the rotary shaft 46, causes a circular motion in the electroless plating solution. The plated object 54 is electrolessly plated.

  The rotational speed of the rotating shaft 46 is preferably 600 to 3000 times / minute, and more preferably 900 to 2000 times / minute.

  As the object to be plated, a rod-shaped, cylindrical or bottomed cylindrical shape is suitable. Specifically, a metal shaft, a bolt, a nail, etc. are illustrated. Moreover, it is a rod-like thing and is easy to be deformed or damaged such as a glass part, a ceramic part, or a decorative article.

  As the electroless plating solution, various electroless plating solutions can be used without particular limitation. Particularly preferred electroless plating solutions include electroless plating solutions for forming noble metal films such as gold and platinum. Depending on the size of the plating container and the object to be plated, the plating area, and the plating film thickness, the plating solution can be used as it is or adjusted to the amount of solution in which the object to be plated is immersed by dilution. Examples of such a platinum plating solution include the plating solution described in “Electroless plating basics and applications-” edited by Electroplating Research Society, Nikkan Kogyo Shimbun (1994) pp.201-202, and has a high platinum ion concentration. The plating time can be shortened using an electroless plating solution. The concentration of each component constituting the plating solution is preferably 1 to 100 times, more preferably 1 to 50 times.

  In the above embodiment, the gear portion 42 is composed of the five gears 44, but the present invention is not limited to this, and any number of gears can be used. In this case, the number of plating tanks 28, the number of plating tank insertion holes 24 of the rack 14, and the like may be adjusted according to the number of gears 44 of the gear portion 42.

  During electroless plating, the vibrator 33 may be operated to apply vibration to the entire plating apparatus. By applying vibration, it is possible to avoid the generation of gas pits caused by the hydrogen gas or nitrogen gas generated along with the decomposition of the reducing agent during plating and adhering to the surface of the plating film.

  In addition, when plating of the inner surface of the object to be plated is not necessary, or when the object to be plated has a columnar shape with no hollow portion, supplying the plating solution into the object to be plated through the cylindrical rotating shaft 46 is omitted. .

  FIG. 4 shows another example of the adapter. In the example of the eccentric adapter 80, the adapter upper part 82 connected to the rotating shaft 46 and the adapter lower part 86 connected to the object 84 are not aligned with each other but eccentric. That is, the adapter 80 is formed so as to be stepped at the intermediate portion. The distance (eccentric distance) between the upper axis and the lower axis of the adapter 80 is preferably 0.5 to 30 mm, and more preferably 1 to 10 mm. By forming the middle part of the adapter 80 in steps, the axis of the object to be plated performs a circular motion with a radius of 0.5 to 30 mm, preferably 1 to 10 mm.

  Hereinafter, the case where electroless platinum plating is performed using the above apparatus will be described in detail.

Example 1
Using the electroless plating apparatus shown in FIG. 1, platinum electroless plating of a predetermined pattern was simultaneously performed on the outer surface and inner surface of five objects to be plated.

  The object to be plated was obtained by forming a catalyst layer having a predetermined pattern on the outer and inner surfaces of a bottomed cylindrical ceramic having a length of 4 cm and a diameter of 1 cm. The inclination angle between the axis of the object to be plated and the axis of the rotating shaft was 3 degrees. The plating tank was a polypropylene test tube having an inner diameter of 1.4 cm and a length of 15 cm. The plating solution (stock solution) was diluted 10 times and plated at a plating solution temperature of 70 ° C. for 1 hour. The rotation speed of the object to be plated was 1000 times / minute. The obtained plating film was uniform and good. When the plating was finished, the platinum ions in the plating solution were almost completely consumed (consumption rate 98%). The composition of the plating solution (stock solution) used is described below.

Used plating solution (stock solution) composition ・ Platinum ethylenediamine complex salt ・ ・ ・ ・ ・ ・ 10g / L as platinum
・ Ammonia water ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 120ml / L
・ Hydrazine monohydrate ・ ・ ・ ・ ・ ・ ・ ・ 50ml / L
・ Water ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Remainder ・ pH ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 11

Example 2
The inclination adapter was removed, and an eccentric adapter (adapter 80 shown in FIG. 4) in which the axis of the rotating shaft and the axis of the object to be plated were eccentric by 1 mm was attached. The same plating object as that used in Example 1 was attached to the eccentric adapter without being inclined. Except for this, the operation was performed under the same conditions as in Example 1. After the plating was finished, the obtained coating was evaluated. The thickness of the obtained plating film was uniform and had a good appearance. When the plating was completed, platinum ions in the plating solution used on the outer surface were almost completely consumed (consumption rate 98%).

Comparative Example 1
The inclination adapter was removed from the plating apparatus shown in FIG. 1, and the same object to be plated as in Example 1 was directly attached to the synthetic resin tube 52. Therefore, the axis of the rotating shaft coincided with the axis of the workpiece. Except for this, the operation was performed under the same conditions as in Example 1. After the completion of plating, the obtained film was observed. As a result, a film having a good appearance at first glance was obtained. The platinum ions in the plating solution were almost completely consumed (consumption rate 98%), but a plating film having a uniform thickness could not be obtained.

Comparative Example 2
The rotation of the rotating shaft of the plating apparatus shown in FIG. 1 was stopped, and plating was performed in a stationary state. Except this, the operation was performed under the same conditions as in Example 1. After the completion of plating, the obtained film was observed.

  The platinum ions in the plating solution remained at 20%, and the plating film had blackish uneven appearance, and a plating film having a uniform thickness could not be obtained.

Comparative Example 3
The inclination of the inclination adapter of the plating apparatus shown in FIG. Since the radius of the circular motion at the other end of the object to be plated is increased, the diameter of the cylindrical plating tank was increased to 7 cm.

  For this reason, the plating solution used was 50 times that of Example 1 (the stock solution was diluted 500 times). Plating was carried out in the same manner as in Example 1.

  The film obtained after the completion of plating was observed. Appearance was good. However, 30% of the platinum ions in the plating solution remained. In the case of Comparative Example 2, the plating film was as good as Example 1. However, in order to increase the diameter of the plating tank and immerse the object to be plated, it is necessary to increase the amount of the solution, which increases the dilution rate of the plating solution and lowers the consumption rate of platinum ions, which is uneconomical.

Comparative Example 4
Plating was carried out by stopping the rotation of the rotating shaft of the plating apparatus and operating in the same manner as in Comparative Example 2. However, the plating time was extended until platinum ions were almost completely consumed. The consumption rate of platinum ions was 93%, requiring 5 hours to complete the plating, and the productivity was poor.

100 Electroless Plating Equipment 2 Base 4 Stirrer 6 Heating Tank 8 Heating Medium 10 Heater
12 Control device 14 Rack 16 Locking portion 18 Bottom plate 20 Middle plate 22 Upper plate 24 Middle plate plating tank insertion hole 26 Upper plate plating tank insertion hole 28 Plating tank 30 Support frame 32 Stirring portion fixing arm 34 Through hole 33 Vibrator 36 Stirring Part 38 Stirring part substrate 40 Stirring part mounting means 42 Gear part 44 Gear 46 Rotating shaft 48 One end side 50 Inclined adapter 52 Synthetic resin tube 54 To-be-plated object 56 One end 58 Connection gear 60, 62 Transmission gear 64 Driving motor 66 Driving gear 70 Others End 80 Eccentric adapter 82 Upper part 84 Plated object 86 Lower part

Claims (14)

A support frame;
A heating tank fixed to the support frame;
A rack disposed in the heating tank and having a predetermined number of plating tank insertion holes;
A stirring part fixing arm disposed above the plating tank across the plating tank;
A stirring unit mounting means for detachably mounting the stirring unit to the stirring unit fixing arm, and a gear unit including a predetermined number of gears meshing with each other, and the rotating shaft of each gear bends at a predetermined angle. A stirrer for connecting a to-be-plated object mounting adapter or a to-be-plated object mounting adapter that is eccentric with the rotating shaft, and each gear is located above each plating tank insertion hole and attached to a stirrer fixing arm,
A motor having a drive gear meshing with any gear of the stirring unit;
An electroless plating apparatus comprising:   The rotating shaft of the gear and the adapter for mounting the object to be plated are formed of a cylindrical body communicating with each other inside, and one end of the cylindrical object to be plated with the other end closed is attached to the adapter for mounting the object to be plated. The electroless plating apparatus according to claim 1, wherein the plating solution is supplied into the object to be plated through the communicating cylinder. The electroless plating apparatus according to claim 1, further comprising a vibrator connected to the support frame. The electroless plating apparatus according to claim 1, wherein the plating tank is formed in a bottomed cylindrical shape. The electroless plating apparatus according to claim 1, wherein the plating solution supplied to the plating tank is an electroless platinum plating solution. The electroless plating apparatus according to claim 1, wherein the object to be plated is formed in a cylindrical shape with the other end closed. The other end of the object to be plated is rotated by rotating the rotating shaft in a state where the rod-shaped object to be tilted at a predetermined angle with respect to the axial direction of the rotating shaft is immersed in the electroless plating solution. An electroless plating method in which plating is performed while circularly moving. The axis of the object to be plated is obtained by eccentrically aligning the axis of the rotating shaft and the axis of the rod-shaped object to be plated, attaching the object to the rotating shaft, and rotating the rotating shaft while immersed in the electroless plating solution. An electroless plating method in which plating is performed while circularly moving. The electroless plating method according to claim 7 or 8, wherein the rod-shaped object to be plated has a hollow portion closed at the other end, and an electroless plating solution is injected into the hollow portion to perform plating. The electroless plating method according to claim 7 or 8, wherein the electroless plating solution is an electroless platinum plating solution. The electroless plating method according to claim 7 or 8, wherein the rotational speed of the rotary shaft is 600 to 3000 times / minute. The electroless plating method according to claim 7, wherein the axis of the object to be plated is inclined by 1 to 40 degrees with respect to the axial direction of the rotating shaft. The electroless plating method according to claim 8, wherein the axis of the rotary shaft and the axis of the rod-shaped workpiece are eccentric by 0.5 to 30 mm. The electroless plating method according to claim 7 or 8, wherein metal ions in the plating solution are used up in one plating.

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