JP3827276B2 - Barrel electroplating method for extremely small articles - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plating method, and more particularly, to a method for plating an extremely small article to be plated in a barrel.
[0002]
[Prior art and problems to be solved by the invention]
Conventionally, electroplating for forming a film of a conductive material on the surface of an article has been widely used in the field of manufacturing articles such as electronic components.
[0003]
In particular, recently, in order to satisfy the demand for downsizing and high functionality of electronic devices, an extremely small electronic component (for example, a ceramic chip 0603 having a vertical and horizontal dimension of 60 μm × 30 μm and a ceramic chip 0402 having a vertical and horizontal dimension of 40 μm × 20 μm) There is a demand for a ceramic chip resistor having metal electrode layers at both ends. In addition, for example, for the production of a conductive resin, a metal powder having a particle size of about 300 μm or a metal-coated synthetic resin powder is contained in a synthetic resin. As these ultra-small articles, a metal layer with good conductivity is firmly attached by electroplating to the entire surface or a desired part of the article to be plated made of metal or the article to be plated made of synthetic resin or ceramic processed to be a conductor. Used.
[0004]
By the way, when electroplating a to-be-plated article having a relatively small size, so-called barrel plating capable of simultaneously plating a large number of to-be-plated articles is used. In barrel plating, a large number of articles to be plated having a volume of about 1/3 are accommodated in a container called a barrel having a large number of small holes through which a plating solution can flow, and an anode is placed in a plating bath outside the barrel. Disposing a member, disposing a cathode member in contact with the article to be plated in the barrel, rotating the barrel around the non-vertical direction (rotating), and rolling the article to be plated in the barrel By applying a voltage to the anode member, the articles to be plated are brought into contact with each other to be electrically connected to the cathode member, and a required conductive surface of the surface of the article to be plated is formed as a cathode surface, and a plating film is formed thereon. Form.
[0005]
Regarding barrel plating, the present applicant has proposed a method of performing chromium plating while vibrating and stirring a plating bath in Japanese Patent Application Laid-Open No. 6-330395. Further, the present applicant has proposed a plating method in which plating is performed while vibrating and agitating a plating bath and vibration is applied to an object to be plated at that time in Japanese Patent Application Laid-Open No. 7-126896. However, as can be seen from these methods, for example, a cylindrical body having a diameter of 30 mm and a length of 50 mm is exemplified as an article to be plated, when the average value of dimensions in three directions orthogonal to each other is used as the average diameter Those having an average diameter larger than about 5 mm are used, and this does not take into account barrel plating of an extremely small article to be plated having an average diameter of 1 mm or less, which has been required in recent years.
[0006]
In the case of barrel plating an extremely small article to be plated, there is a specific technical problem. That is, in the case of an extremely small article to be plated, aggregation of the articles to be plated is likely to occur in the barrel, and the rolling of the article to be plated during the rotation of the barrel becomes insufficient, and plating on the required plating film forming portion is performed. The fluidity of the liquid is extremely reduced. For this reason, the thickness of the plating film to be adhered to the surface with a uniform film thickness is partially non-uniform, and the film formation state for each individual is also non-uniform, resulting in a significant decrease in the overall yield rate. In particular, adhesion of articles to be plated tends to occur.
[0007]
In addition, the film formation rate tends to decrease, and it is difficult to improve productivity. In particular, in the case of an extremely small article to be plated, the size of a large number of small holes formed in the barrel must be reduced. Improvement tends to be difficult. If an attempt is made to increase the current density in order to improve the film formation rate, the nonuniformity of the plating film thickness is further increased, and the yield rate is reduced due to the occurrence of burns or burns. For this reason, hitherto, such barrel plating of extremely small articles has not been put to practical use.
[0008]
In addition, although the surface of the synthetic resin particles can be plated by, for example, electroless plating, it is difficult to increase the plating film thickness without electroplating. Application is desirable.
[0009]
Accordingly, one of the objects of the present invention is to make the thickness of the plating film formed on a required portion uniform when barrel electroplating an article to be plated of extremely small dimensions, and to improve the yield rate.
[0010]
Another object of the present invention is to increase the deposition rate of the plating film and improve the productivity when performing barrel electroplating on an extremely small article to be plated.
[0011]
[Means for Solving the Problems]
According to the present invention, the above object is achieved as follows:
A plurality of articles to be plated are accommodated in a barrel having a large number of small holes through which a plating solution can pass, and the barrel is moved in a plating bath while being arranged in contact with the article to be plated in the barrel. A barrel electroplating method of forming a plating film on the surface of the article to be plated by applying a voltage between the cathode member and the anode member disposed in the plating bath outside the barrel,
The article to be plated has an average diameter of 5 to 500 μm,
A vibration blade fixed in one or more stages to a vibrating rod that vibrates in the plating bath linked to vibration generating means has an amplitude of 0.1 to 10.0 mm and a vibration frequency of 200 to 800 times / minute in the plating bath. Barrel electroplating of a small article characterized by generating vibration flow in the plating bath by vibrating and vibrating the barrel at an amplitude of 0.1 to 5.0 mm and a frequency of 100 to 300 times / minute. Method,
Is provided.
[0012]
In one aspect of the present invention, the article to be plated is made of a metal or a synthetic resin or ceramic subjected to a conductor treatment. In one aspect of the present invention, the barrel motion is a rotational motion about a non-vertical rotation center. In one aspect of the present invention, the vibration flow of the plating bath has a three-dimensional flow rate of 150 mm / second or more. In one aspect of the present invention, the diameter of the small hole in the barrel is 3 to 300 μm. In one aspect of the present invention, the vibration generating means vibrates at 10 to 500 Hz.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. In the drawings, members or parts having similar functions are denoted by the same reference numerals.
[0014]
1 and 2 are sectional views showing the configuration of a plating apparatus in which the first embodiment of the plating method according to the present invention is implemented, and FIG. 3 is a plan view thereof.
[0015]
In these drawings, reference numeral 12 denotes a plating tank, and a plating bath 14 is accommodated in the plating tank. 16 is a vibration flow generation part. The vibration flow generator 16 is fixed to the base 16a attached to the plating tank 12 through vibration-proof rubber, a coil spring 16b as a vibration absorbing member having a lower end fixed to the base, and an upper end of the coil spring. A vibration member 16c, a vibration motor 16d as vibration generating means attached to the vibration member, a vibration transmission rod 16e having an upper end attached to the vibration member 16c, and a position where the lower half of the vibration transmission rod is immersed in the plating bath 14 The vibration blade 16f is attached to. A rod-shaped guide member can be disposed in the coil spring 16b as shown in FIG.
[0016]
The vibration motor 16d vibrates at 10 to 500 Hz, preferably 20 to 60 Hz, more preferably 30 to 50 Hz, for example, by control using an inverter. The vibration generated by the vibration motor 16d is transmitted to the vibration blade 16f via the vibration member 16c and the vibration transmission rod 16e. The tip edge of the vibrating blade 16f vibrates at a required frequency in the plating bath 14. This vibration is generated so that the vibration blade 16f “shaves” from the attachment portion to the vibration transmission rod 16e to the tip edge. The amplitude and frequency of this vibration are different from those of the vibration motor 16d, but are determined according to the mechanical characteristics of the vibration transmission path and the characteristics of the interaction with the plating bath 14, etc. It is preferable that the vibration frequency is 200 to 800 times / minute at 10.0 mm.
[0017]
FIG. 4 is an enlarged cross-sectional view of a portion where the vibration transmission rod 16e is attached to the vibration member 16c. Nuts 16i1, 16i2; 16i3, 16i4 are fitted to the male thread portion formed at the upper end of the vibration transmitting rod 16e via the vibration stress dispersion members 16g1, 16g2 and washers 16h1, 16h2 from the upper and lower sides of the vibration member 16c. The vibration stress dispersion members 16g1 and 16g2 are made of rubber, for example.
[0018]
FIG. 5 is an enlarged cross-sectional view of the attachment portion of the vibration blade 16f to the vibration transmission rod 16e. Vibrating blade fixing members 16j are arranged on both upper and lower sides of each of the seven vibrating blades 16f. A spacer ring 16k for setting the interval between the vibration blades 16f is disposed between the adjacent vibration blades 16f via a fixing member 16j. On the upper side of the uppermost vibration blade 16f and the lower side of the lowermost vibration blade 16f, a nut 16m that fits the male screw formed on the vibration transmission rod 16e is disposed.
[0019]
FIG. 6 is a view showing a modification of the attachment portion of the vibration blade 16f to the vibration transmission rod 16e. In this modification, each vibration blade 16f is individually attached to the vibration transmission rod 16e by upper and lower nuts 16n. In addition, the vibration member 16f can be prevented from being damaged by interposing an elastic member sheet 16p made of a fluorine-based resin or fluorine-based rubber between the vibration member 16f and the fixing member 16j. As shown in the drawing, the lower surface (pressing surface) of the upper fixing member 16j is a convex cylindrical circle, and the upper surface (pressing surface) of the lower fixing member 16j is a corresponding concave cylindrical circle. Thereby, the portion of the vibrating blade 16f pressed from above and below by the fixing member 16j is curved, and the tip of the vibrating blade 16f forms an angle α with respect to the horizontal plane. This angle α can be, for example, −30 ° to 30 °, preferably −20 ° to 20 °. In particular, the angle α is preferably −30 ° to −5 ° or 5 ° to 30 °, more preferably −20 ° to −10 °, or 10 ° to 20 °. When the pressing surface of the fixing member 16j is a plane, the angle α is 0 °. The angle α need not be the same for all the vibrating blades 16f. For example, as shown in FIG. 1, the angle α is a minus value (ie, downward: in FIG. 6 for the lower one or two vibrating blades 16f. The other vibrating blades 16f can be set to a positive value (that is, upward: the direction shown in FIG. 6).
[0020]
As the vibrating blade 16f, an elastic metal plate, a synthetic resin plate, a rubber plate, or the like can be used. The thickness of the vibration blade 16f is set so that the tip edge portion of the vibration blade 16f exhibits a flutter phenomenon (a state of undulation) when the vibration flow generator 16 is actuated. When the vibrating blade 16f is made of a metal plate such as a stainless steel plate, the thickness can be set to 0.2 to 2 mm. Further, when the vibration blade 16f is made of a synthetic resin plate or a rubber plate, the thickness can be set to 0.5 to 10 mm.
[0021]
1 to 3, a vibration frame 44 is attached to the plating tank 12 via a coil spring 46 as a vibration absorbing member. A vibration motor 48 and a balance weight 49 for balancing the weight with the vibration motor 48 are attached to the vibration frame 44. A barrel 52 is attached to the vibration frame 44 via a support member 50. The barrel is rotatably attached to the support member 50, and is rotated in a direction indicated by an arrow in FIG. 1 by a driving means (not shown). The number of rotations of the barrel 52 is, for example, 1 to 15 times / minute. In general barrel plating, the number of rotations is fixed to about 6 to 8 times / minute, but in the present invention, 3 times / minute, 5 times / minute, or 8 depending on the state of the article to be plated. It is preferable to control appropriately such as times / minute. For example, when plating on resin particles, the specific gravity is small before plating, so if the rotational speed is increased too much, it tends to adhere to the barrel wall surface, and therefore a relatively small rotational speed is used. Since the specific gravity of is increased, the rotational speed can be increased.
[0022]
A large number of extremely small articles X to be plated are accommodated in the barrel 52. On the outer peripheral surface of the barrel 52, a large number of small holes that prevent the article to be plated X from passing and allow the liquid (plating solution) in the plating bath 14 to pass are formed. In the barrel 52, a cathode conductive member 54 extending to the lower portion thereof is disposed. The cathode conductive member 54 is connected to the negative terminal of the power supply circuit 34 through the pipe member 52a attached to the barrel at the center of rotation of the barrel 52 via the insulation coating wiring 54 '. The cathode conductive member 54 does not rotate during the barrel rotation, so the article X to be rolled that rolls along with the barrel rotation repeats contact with the cathode conductive member 54 and separation from the cathode conductive member 54. The barrels used are not limited to those shown here, but are known in various forms (however, the size of the small aperture is 5 to 5 in average diameter in the present invention). (The one having a diameter of 3 to 300 μm which can prevent the passage of a 500 μm very small article) can be used.
[0023]
Reference numeral 56 denotes an anode metal member having a lower part immersed in the plating bath 14. The anode metal member 56 is accommodated in, for example, a plastic bag, and is connected to the positive terminal of the power supply circuit 34 via an insulation coating wiring 56 '. As shown in FIG. 1, the anode metal member 56 is disposed on both sides of the barrel 52. However, the anode metal member 56 may be disposed only on one side.
[0024]
The vibration motor 48 vibrates at 10 to 60 Hz, preferably 20 to 35 Hz, for example, by control using an inverter. The vibration generated by the vibration motor 48 is transmitted to the barrel 52 via the vibration frame 44 and the support member 50, whereby the barrel 52 and thus the article to be plated X have an amplitude of 0.1 to 5.0 mm and a vibration frequency of 100 to 300 times. Vibrates at / min.
[0025]
The power supply circuit 34 can generate a DC voltage from an AC voltage. Such a power supply circuit has a rectifier circuit using a transistor, for example, and is known as a rectifier. As a power supply circuit (power supply device) used for generating a plating current in the present invention, a known circuit that rectifies alternating current (including addition of a direct current component) and outputs it is used.
[0026]
The plating bath 14 is selected in the same manner as a known electroplating method according to the type of plating, that is, the plating film to be formed. Types of plating include, for example, copper sulfate plating, copper cyanide plating, copper pyrophosphate plating, nickel plating, black nickel plating, nickel sulfamate plating, chromium plating, zinc cyanide plating, noncyanide zinc plating, alkaline tin plating, Acid tin plating, neutral tin plating, silver plating, gold cyanide plating, acid gold plating, copper-zinc alloy plating, nickel-iron alloy plating, tin-lead alloy plating, palladium plating, solder plating, etc. .
[0027]
For example, when performing copper sulfate plating, as a through-hole bath,
Copper sulfate: 60-100 g / L (liter)
Sulfuric acid: 170-210 g / L
Brightener: appropriate amount
Chlorine ion: 30-80mL / L
As a normal bath,
Copper sulfate: 180-250 g / L
Sulfuric acid: 45-60 g / L
Brightener: appropriate amount
Chlorine ion: 20-80mL / L
Can be used.
[0028]
For example, when performing nickel plating, as a barrel bath,
Nickel sulfate: 270 g / L
Nickel chloride: 68g / L
Boric acid: 40 g / L
Magnesium sulfate: 225 g / L
As a normal bath,
Nickel sulfate: 150 g / L
Ammonium chloride: 15 g / L
Boric acid: 15 g / L
Can be used as a watt bath,
Nickel sulfate: 240 g / L
Ammonium chloride: 45 g / L
pH: 4-5
Bath temperature: 45-55 ° C
Can be used.
[0029]
For example, when performing acidic tin plating, as a sulfate bath,
Stannous sulfate: 50 g / L
Sulfuric acid: 100 g / L
Cresol sulfonic acid: 100 g / L
Gelatin: 2g / L
β-naphthol: 1 g / L
Can be used.
[0030]
The article to be plated X is a minimum one having an average diameter of 5 to 500 μm. Here, the average diameter means an average value of representative dimensions in three directions orthogonal to each other. Examples of such an article X to be plated include copper powder, metal powder such as pre-treated aluminum powder and iron powder, synthetic resin powder such as conductor-treated ABS resin powder, conductor chip-treated ceramic chip, etc. Can be illustrated. In addition, other electronic parts, machine parts, metal powder alloys, fine inorganic / organic pigments, metal balls, and the like can be given.
[0031]
For example, a composite plating film can be formed by forming a Ni plating film on metal particles having a diameter of about 300 μm, such as Cu particles, or by forming an Au plating film or an Ag plating film on the Ni plating film.
[0032]
Within the barrel 52, several thousand to several hundreds of thousands of articles X to be plated can be accommodated. The dimensions of the barrel are, for example, 50 to 200 mm in diameter and 100 to 250 mm in length. Further, the size of the small holes in the barrel 52 is such that passage of the article to be plated X is prevented, and the opening ratio as a ratio of the total small hole area to the surface area of the entire outer peripheral surface is 25 to 75. %.
[0033]
In the plating method of the present invention, the flow of the plating solution into the barrel 52 through the small aperture is improved by the vibration flow generated in the plating bath 14 by the vibration flow generation section 16. Also in 52, the flowability of the plating solution between the objects X to be plated adjacent to each other is improved. Further, in the present embodiment, the barrel 52 is vibrated, thereby preventing the objects to be plated X from agglomerating in the barrel 52 and allowing them to roll sufficiently, and between the objects to be plated X adjacent to each other. This further improves the flowability of the plating solution, and achieves better film thickness uniformity and film formation speed.
[0034]
Further, in the present invention, due to the action of vibration flow generated in the plating bath 14, even if the distance between the article X to be plated and the anode metal member is shortened and the current density is increased, short-circuiting hardly occurs. This is also considered to be a factor capable of forming a plating film with a good yield and high speed without causing defects such as burns and burns.
[0035]
In order to obtain such an effect satisfactorily, it is extremely preferable that the three-dimensional flow velocity of the vibration flow of the plating bath 14 is 150 mm / second or more. Such a high three-dimensional flow rate is effectively realized by vibrating and flowing the plating bath, and is difficult to realize by ordinary stirring and requires a very large apparatus configuration even if realized. There is a disadvantage.
[0036]
Prior to carrying out the electroplating method according to the present invention, a necessary pretreatment process is performed on the article X to be plated, if necessary. These pretreatments may be performed in the same manner as in the case of a conventionally known electroplating method. Examples of this pretreatment include the following treatment steps and water washing steps.
[0037]
Degreasing:
Sodium borate 20g / liter (L)
Sodium phosphate 20g / L
Surfactant 2g / L
40-60 ° C
3-5 minutes
etching:
Chromic acid 400g / L
Sulfuric acid 400g / L
65-70 ° C
5-15 minutes
Neutralization:
Concentrated hydrochloric acid 50mL / L
room temperature
30-60 seconds
Catalyst:
Palladium chloride 0.2g / L
Stannous chloride 5-20g / L
Hydrochloric acid 100-200mL / L
room temperature
2-5 minutes
Accelerator:
Sulfuric acid 50-100 mL / L or
Hydrochloric acid 80-150mL / L
30-50 ° C
2-6 minutes
Electroless nickel plating:
Nickel sulfate 30g / L
Sodium hypophosphite 20g / L
Ammon citrate 50g / L
pH 7.5-9.5
30-40 ° C
5-10 minutes
In particular, when electroplating is performed on powder or particles made of a synthetic resin (plastic), the above-described conductive step is required. Even during such treatment, the treatment time can be significantly reduced by vibrating and stirring the treatment bath.
[0038]
After the pretreatment as described above, the electroplating treatment of the present invention is performed. Electroplating is performed, for example, in the following process.
[0039]
Copper sulfate plating:
Copper sulfate 200-240g / L
Sulfuric acid 50-60g / L
Appropriate amount of brightener
20-28 ° C
Current density 2-4A / dm²
15-40 minutes
Then, after alcohol washing, it dries.
[0040]
In the case of a plastic material, as the treatment step of the present invention including the above pretreatment, for example, degreasing → water washing → etching → water washing → neutralization → water washing → catalyst (catalyst imparting) → water washing → accelerator (activation) → Water washing → no electroplating → water washing → electroplating → water washing → drying. That is, in the case of a plastic material, in order to form an electroplated film on the surface, it is necessary to form a conductive film on the surface in advance to make a conductor. Electroplating is performed in the same manner as the material. The surface conductive resin particles or resin powder obtained in this way are solder bonded when the electroplating film is a tin film or a laminated film made of a solder film or other alloy solderable material film. It can be used as a solder material in which the synthetic resin evaporates and the volume is reduced by heating and melting.
[0041]
In the case of a metal material, examples of the treatment step of the present invention including the pretreatment include degreasing → water washing → accelerator (activation) → water washing → electroplating → water washing → drying.
[0042]
In addition, as the vibration flow generation section provided with the vibration blades used for generating the required vibration flow in the plating bath in the method of the present invention, the one described in JP-A-11-189880 (for example, the publication) As shown in FIGS. 7 to 8, the vibration blades are arranged at the bottom of the plating tank, the vibration is transmitted from the vibration motor to the vibration blades through the vibration transmission frame, and the vibration blades are horizontally arranged. And those described in the publications cited in the publication can be used as appropriate.
[0043]
FIG. 7 is a sectional view showing another embodiment of the plating apparatus used for carrying out the plating method according to the present invention, and FIG. 8 is a partially cutaway plan view thereof. In this embodiment, the configuration of the vibration flow generating unit 16 is different from that in the above embodiment. That is, the lower end of the coil spring 16b is fixed to the attachment member 118 fixed to the upper end edge of the plating tank 12, and the vibration motor 16d is attached to the lower side of the vibration member 16c to which the upper end of the coil spring 16b is fixed. It has been. In the coil spring 16b, a lower guide member 124 whose lower end is fixed to the attachment member 118 and an upper guide member 123 whose upper end is fixed to the vibration member 16c are arranged at an appropriate interval.
[0044]
In the present invention, it is also possible to perform so-called pulse plating by applying a pulse voltage instead of a DC voltage by the power supply circuit 34. In that case, the power supply circuit 34 can generate a rectangular wave voltage from an AC voltage, and such a power supply circuit has a rectifier circuit using a transistor, for example, and is known as a pulse power supply device. .
[0045]
As a power supply circuit (power supply device) used for generating a plating current in the present invention, a circuit that rectifies alternating current (including addition of a direct current component) and outputs it is used. Examples of such power supply devices or rectifiers include transistor-regulated power supplies, dropper-type power supplies, switching power supplies, silicon rectifiers, SCR-type rectifiers, high-frequency rectifiers, and inverter digital control rectifiers (eg, Power manufactured by Chuo Seisakusho Co., Ltd.). Master), KTS series manufactured by Sansha Electric Manufacturing Co., Ltd., RCV power supply manufactured by Shikoku Electric Co., Ltd., and a switching regulator type power supply and transistor switch, and a rectangular wave pulse current is supplied by turning the transistor switch on and off. High-frequency switching power supply (After converting AC to DC with a diode, add 20-30 KHz high-frequency power to the transformer to rectify and smooth the output again), PR rectifier, high-frequency control system high-speed Pulse PR power supply ( Such as HiPR series (Co., Ltd. Chiyoda) is available if example.
[0046]
FIG. 9 is a graph showing a change in plating current (current density) flowing through the article to be plated X based on the voltage applied between the cathode and the anode by the power supply circuit 34. As illustrated, the plating current has a first state that lasts for a first time T1 at a first value I1 and a second state that lasts for a second time T2 at a second value I2 (<I1). It seems to appear alternately. Here, the first value I1 and the second value I2 have the same polarity. I1 is 6 times or more (for example, 6 to 25 times) of I2, and preferably 8 to 20 times. Moreover, T1 is 4 times or more (for example, 4 to 25 times) of T2, and preferably 6 to 20 times. By combining such a plating current and the vibration flow of the plating bath 14 by the vibration flow generating section 16, good quality and high film formation speed can be obtained even in the plating of a fine conductive structure pattern.
[0047]
The first value I1 and the first time T1 are appropriately set according to the type of plating or the composition of the plating bath. For example, I1 is 0.01 to 100 [A / dm.² ], And T1 can be in the range of 3 to 300 [seconds]. However, it is not limited to this, and optimal I1, I2, T1, and T2 may vary in a wide range depending on the type of plating and the composition of the plating bath. It changes as the composition of the plating bath changes.
[0048]
10 and 11 are cross-sectional views showing other forms of attachment of the vibration flow generating portion constituting the plating apparatus used for carrying out the plating method according to the present invention to the plating tank, and FIG. 12 is a plan view thereof. is there. 10 and 11 correspond to the X-X ′ cross section and the Y-Y ′ cross section of FIG. 12, respectively. In these figures, a barrel, a cathode, an anode, a power supply circuit, and the like for plating are not shown.
[0049]
In this embodiment, a laminate 3 of the rubber plate 2 and the metal plates 1 and 1 'is used as a vibration absorbing member in place of the coil spring 16b. That is, the laminated body 3 fixes the metal plate 1 ′ attached via the anti-vibration rubber 112 to the attachment member 118 fixed to the upper end edge of the plating tank 12 with the bolt 131, and on the metal plate 1 ′. The rubber plate 2 is disposed, the metal plate 1 is disposed on the rubber plate 2, and these are integrated by bolts 116 and nuts 117.
[0050]
The vibration motor 16 d is fixed to the metal plate 1 by a bolt 132 via a support member 115. Further, the upper end portion of the vibration transmission rod 16 e is attached to the laminate 3, particularly the metal plate 1 and the rubber plate 2 through a rubber ring 119. That is, the upper metal plate 1 also exhibits the function of the vibration member 16c of the embodiment described in FIG. 1 and others, and the lower metal plate 1 ′ is the base of the embodiment described in FIGS. The function of the table 16a is also demonstrated. And the laminated body 3 (mainly rubber plate 2) containing these metal plates 1 and 1 'exhibits the vibration absorption function similar to the coil spring 16b described in FIG.
[0051]
FIG. 13 shows a plan view of the laminate 3. In the example of FIG. 13A corresponding to the form of FIGS. 10 to 12, the laminated body 3 is formed with a through hole 5 through which the vibration transmission rod 16 e is passed. In the example of FIG. 13 (b), the laminate 3 is composed of two parts 3a and 3b divided into two by a dividing line passing through the through-hole 5. According to this, the vibration transmission rod 16e is arranged at the time of assembling the apparatus. Can be passed easily. In the example of FIG. 13C, the laminate 3 has a ring shape corresponding to the upper end edge of the plating tank 12, and an opening 6 is formed in the center.
[0052]
In the example of FIGS. 13A and 13B, the upper part of the plating tank 12 is closed by the laminated body 3, so that the gas volatilized from the plating bath 14 and the plating solution that scatters to the surroundings during the plating process. Leakage can be prevented.
[0053]
FIG. 14 is a cross-sectional view showing a state in which the upper part of the plating tank is blocked (seal) by such a laminate 3. In the form of FIG. 14 (a), the rubber plate 2 is brought into contact with the vibration transmission rod 16e in the through hole 5 for sealing. 14B, a flexible seal member 136 that is attached to the laminated body 3 and the vibration transmission rod 16e in the opening 6 of the laminated body 3 and closes the gap between them is provided.
[0054]
FIG. 15 shows an example of the laminate 3 as a vibration absorbing member. The example of FIG.15 (b) is a thing of embodiment of the said FIGS. 10-12. In the example of FIG. 15A, the laminate 3 is composed of a metal plate 1 and a rubber plate 2. In the example of FIG. 15C, the laminate 3 is composed of an upper metal plate 1, an upper rubber plate 2, a lower metal plate 1 ', and a lower rubber plate 2'. In the example of FIG. 15D, the laminate 3 includes an upper metal plate 1, an upper rubber plate 2, an intermediate metal plate 1 ″, a lower rubber plate 2 ′, and a lower metal plate 1 ′. The number of metal plates and rubber plates can be, for example, 1 to 5. In the present invention, the vibration absorbing member can also be configured only from rubber plates.
[0055]
Stainless steel, iron, copper, aluminum, and other appropriate alloys can be used as the material of the metal plates 1, 1 ′, 1 ″. The thickness of the metal plate is, for example, 10 to 40 mm. A metal plate that is not directly fixed to a member other than the laminate (for example, the intermediate metal plate 1 ″) can be as thin as 0.3 to 10 mm.
[0056]
As the material for the rubber plates 2 and 2 ', synthetic rubber or natural rubber vulcanizate can be used, and vibration-proof rubber defined by JISK6386 is preferable, and static shear modulus of elasticity is 4 to 22 kgf / cm.² Preferably 5-10 kgf / cm² Further, those having an elongation of 250% or more are preferable. Synthetic rubbers include chloroprene rubber, nitrile rubber, nitrile-chloroprene rubber, styrene-chloroprene rubber, acrylonitrile-butadiene rubber, isoprene rubber, ethylene-propylene-diene copolymer rubber, epichlorohydrin rubber, alkylene oxide rubber, fluorine-based rubber. Examples thereof include rubber, silicone rubber, urethane rubber, polysulfide rubber, and phosphabin rubber. The thickness of the rubber plate is, for example, 5 to 60 mm.
[0057]
In the example of FIG. 15 (e), the laminated body 3 is composed of an upper metal plate 1, a rubber plate 2, and a lower metal plate 1 ′, and the rubber plate 2 includes an upper solid rubber layer 2a, a sponge rubber layer 2b, and a lower side. It consists of a solid rubber layer 2c. One of the lower solid rubber layers 2a and 2c may be removed, or a plurality of solid rubber layers and a plurality of sponge rubber layers may be laminated.
[0058]
【Example】
Hereinafter, the present invention will be described with reference to examples.
[0059]
Example 1:
The apparatus described with respect to FIGS. Here, a vibration motor 16d having a capacity of 150 W × 200 V × 3φ was used, and a plating tank 12 having a capacity of 300 liters was used. Further, as the barrel 52, a barrel having a diameter of 100 mm, a length of 170 mm, a diameter of a small opening of 0.1 mm, and a small hole opening ratio (opening ratio) of 60% on the cylindrical outer peripheral surface was used. .
[0060]
About 80,000 ceramic chip resistors 0603 having a size of 0.6 mm × 0.3 mm × 0.2 mm subjected to predetermined pretreatment by a conventional method were used as the article X to be plated. A dummy ball was added to about 1/3 of the barrel volume. This ceramic chip resistor is formed with a resistor film as a resistor function part, and is connected to both ends of the chip in the longitudinal direction of the chip and the subsequent 0.6 mm × 0. A part of the 3 mm surface (region from both end surfaces to 0.1 mm) was subjected to a conductor treatment for electrode formation.
[0061]
This ceramic chip was degreased by immersing it in a cleaning solution at 50 ° C. containing a neutral detergent of 5 milliliters (mL) / liter (L) for 5 minutes, and then washed with ion-exchanged water at room temperature for 30 seconds. Thereafter, the power supply circuit 34 applied a voltage of 10.5 V between the cathode conductive member 54 and the anode metal member 56 to flow a current of 37 A, and nickel plating was performed for 60 minutes. In the plating bath 14 during nickel plating,
Nickel sulfate: 240 g / L
Nickel chloride: 45g / L
Boric acid: 40 g / L
The temperature of the plating bath 14 was 55 ° C. Thereby, a nickel plating film having a film thickness of 4 μm ± 0.5 μm was formed on a predetermined portion of the ceramic chip.
[0062]
Thereafter, the ceramic chip is washed with normal-temperature city water for 30 seconds, a voltage of 3.0 V is applied between the cathode conductive member 54 and the anode metal member 56 by the power supply circuit 34, and a current of 12 A is applied. Tin plating was performed for a minute. In the plating bath 14 for tin plating,
Stannous sulfate: 50 g / L
Sulfuric acid: 100 g / L
Cresol sulfonic acid: 100 g / L
The temperature of the plating bath 14 was 30 ° C. As a result, a tin plating film having a thickness of 4 μm ± 0.5 μm was formed on the nickel plating film of the ceramic chip.
[0063]
Thereafter, this ceramic chip is washed with ion exchange water at room temperature for 30 seconds, neutralized with 2% sodium phosphate tribasic solution at room temperature, further washed with ion exchange water at room temperature for 30 seconds, and pure water at 70 ° C. For 30 seconds, replaced with pure water with methanol, and dried in an oven at 70 ° C. for 40 minutes.
[0064]
In the above nickel plating and tin plating, the vibration motor 16d of the vibration flow generator 16 is vibrated at 38 Hz, and the vibration blade 16f vibrates in the plating bath 14 with an amplitude of 0.2 mm and a vibration frequency of 750 times / minute. I let you. The vibration motor 48 was vibrated at 25 Hz, and the barrel 52 was vibrated in the plating bath 14 with an amplitude of 0.15 mm and a vibration frequency of 250 times / minute. The rotation speed of the barrel 52 was 8 times / minute. The three-dimensional flow velocity in the plating bath at this time was 200 mm / second when measured with a three-dimensional electromagnetic current meter ACM300-A (manufactured by Alec Electronics Co., Ltd.).
[0065]
For all of the ceramic chip resistors formed as described above, an electrode plating film with good uniformity is formed and there is no adhesion in tin plating (non-defective product rate 100%). The results of other tests were found.
[0066]
Comparative Example 1-1:
When the same processing as in Example 1 was performed except that the vibration motor 48 was not vibrated and therefore the barrel 52 was not vibrated in the plating bath 14, the nickel plating film had an average film thickness of 3 μm (error ± 2 μm). The average thickness of the tin plating film was 3 μm (error ± 2.5 μm), and the yield rate was about 10%. There were very many products attached, and there were many product variations such as film thickness variations.
[0067]
Comparative Example 1-2:
When the same treatment as in Example 1 was performed except that the vibration flow generating unit 16 was not operated, the nickel plating film had an average film thickness of 3.5 μm (error ± 2.5 μm), and the tin plating film had a film thickness. Was 2.7 μm on average (error ± 3 μm), and there was a defect due to burns or burns, and the yield rate was about 5%.
[0068]
As described above, in a small barrel having an opening size of 300 μm or less, the plating solution in the barrel can be flowed only by adding vibration flow stirring to the plating bath with the vibration flow stirring device. It was found that plating failure occurred due to the difference in the concentration of the plating solution inside and outside the barrel.
[0069]
Example 2:
About 3 mL of a ceramic chip resistor 0603 having a size of 0.6 mm × 0.3 mm × 0.2 mm subjected to a predetermined pretreatment as used in Example 1 as the article to be plated X was used, and the diameter was 0.5 mm. Using a dummy ball of 30 mL, a barrel having a diameter of 55 mm, a length of 50 mm, and a small hole diameter of 0.1 mm, the same nickel plating solution as in Example 1 was used at 9.5 V × 7.5 A and 60 Nickel plating was performed for a minute. Thereafter, tin plating was performed at 3.0 V × 2.5 A for 60 minutes with the same tin plating solution as in Example 1. As a result, a product having a nickel plating film thickness of 4 μm and a tin plating film thickness of 4 μm was obtained. The uniformity of the plating film thickness was good, and there were no defective products (good product rate 100%).
[0070]
If the vibration flow generation part is stopped (that is, the generation of the vibration flow of the plating solution by the vibration flow stirring device is stopped), even if the barrel is vibrated, the occurrence of defects due to uneven plating film thickness is extremely large, and the yield rate is About 20%. Further, when the barrel vibration was stopped without stopping the vibration flow generating portion, the yield rate was about 50%.
[0071]
Example 3:
1 to 3 (vibration motors 16d, 48 and plating tank 12 are the same as those in the first embodiment), the barrel 52 has a diameter of 100 mm, a length of 170 mm, and a small opening diameter of 100 μm. An acrylonitrile-butadiene-styrene copolymer (ABS resin) having an average diameter of 300 μm and having a predetermined pre-treatment as a to-be-plated article X by using a conventional method with a small hole opening ratio of 60% on the cylindrical outer peripheral surface ) Was added to about 1/3 of the barrel capacity, and a copper plating film was formed on the entire surface without using a dummy.
[0072]
In addition, pre-processing is the following (a) to (k) degreasing-washing-surface adjustment-washing-pre-dip-catalyst (Sn, Pd) -washing-accelerator (Sn removal) -washing-conductor Chemical nickel plating for electrolysis (electroless nickel plating)-performed by washing with water.
[0073]
(A) Degreasing process
Processing conditions: Cleaner, 55 ° C, 5 minutes
Treatment liquid (40 mL / L):
Organic chelating agent 7.5 (W / V)%
Phosphate 1.0 (W / V)%
Sodium hydroxide 2.5 (W / V)%
Surfactant 1 0.75 (W / V)%
Surfactant 2 0.1 (W / V)%
Water balance
(B) Water washing process
Treatment liquid: Ion exchange water
(C) Surface adjustment process
Treatment conditions: Conditioner, 40 ° C, 5 minutes
Treatment liquid (30 mL / L):
Organic compound 10.0 (W / V)%
Water balance
(D) Water washing process
Treatment liquid: Ion exchange water
(E) Pre-dip process
Treatment conditions: 25 ° C, 1 minute
Treatment liquid (50 mL / L):
35% hydrochloric acid
(F) Catalyst process
Treatment conditions: 40 ° C, 5 minutes
Treatment liquid 1 (30 mL / L):
Palladium salt 0.5 (W / V)%
Tin salt 32.0 (W / V)%
Hydrochloric acid 16.0 (W / V)%
Water balance
Treatment liquid 2 (200 mL / L):
35% hydrochloric acid
(G) Water washing process
Treatment liquid: Ion exchange water
(H) Accelerator process
Treatment conditions: 40 ° C, 5 minutes
Treatment liquid 1 (20 mL / L):
Organic compound 8.0 (W / V)%
Mineral acid salt 2.0 (W / V)%
Water balance
Treatment liquid 2 (100 mL / L):
95% sulfuric acid
(I) Water washing process
Treatment liquid: Ion exchange water
(J) Electroless nickel plating process
Treatment conditions: 40 ° C, 12 minutes
Treatment liquid (125 mL / L):
A Inorganic metal salt 1 17.0 (W / V)%
Inorganic metal salt 2 0.5 (W / V)%
Chelating agent 10.0 (W / V)%
Inorganic ammonium salt 7.5 (W / V)%
Sodium hydroxide 6.0 (W / V)%
Water balance
B Reducing agent 13.0 (W / V)%
Chelating agent 8.0 (W / V)%
Inorganic ammonium salt 4.0 (W / V)%
pH buffer 1 4.0 (W / V)%
pH buffer 2 6.5 (W / V)%
Sodium hydroxide 7.5 (W / V)%
Water balance
(K) Water washing process
Treatment liquid: Ion exchange water
As the plating bath 14 for copper plating,
Copper sulfate: 200 g / L
Sulfuric acid: 50 g / L
Was used. Plating was performed for 60 minutes.
[0074]
The vibration motor 16d of the vibration flow generator 16 was vibrated at 38 Hz by an inverter, and the vibration blade 16f was vibrated in the plating bath 14 with an amplitude of 0.2 mm and a vibration frequency of 700 times / minute. Further, the vibration motor 48 was vibrated to vibrate the article X to be plated in the plating bath 14 with an amplitude of 0.15 mm and a vibration frequency of 250 times / minute. The rotation speed of the barrel 52 was 8 times / minute. The three-dimensional flow velocity in the plating bath at this time was measured with a three-dimensional electromagnetic current meter ACM300-A and found to be 210 mm / second.
[0075]
The synthetic resin powder having a copper plating film on the surface formed as described above has a copper plating film having a good uniformity (film thickness 5 μm ± 0.5 μm) (good product rate 100%), As a result of visual inspection, microscopic inspection of cut section and other inspections.
[0076]
Comparative Example 3-1:
When the same treatment as in Example 2 was performed except that the vibration motor 48 was not vibrated and therefore the barrel 52 was not vibrated in the plating bath 14, the average thickness of the copper plating film was 3 μm (error ± 2 μm). There was a good product rate of about 40%.
[0077]
Comparative Example 3-2:
When the same processing as in Example 2 was performed except that the vibration flow generating unit 16 was not operated, the copper plating film had an average film thickness of 3 μm (error ± 0.6 μm), which was defective due to burns, burns, etc. Occurrence occurred, no gloss, and the yield rate was 0%.
[0078]
Example 4:
The capacity of an acrylonitrile-butadiene-styrene copolymer (ABS resin) powder having an average diameter of 300 μm, which was subjected to a predetermined pretreatment in the same manner as used in Example 3 as the article to be plated X, was added to the barrel used in Example 2. Then, 30 mL of a dummy ball having a diameter of 0.5 mm was placed in the barrel, and nickel plating was performed at 9.5 V × 7.5 A for 60 minutes with the same nickel plating solution as in Example 1. Thereafter, tin plating was performed at 3.0 V × 2.5 A for 60 minutes with the same tin plating solution as in Example 1. As a result, a product having a nickel plating film thickness of 4 μm and a tin plating film thickness of 4 μm was obtained. The plating film thickness uniformity was good and there were no defective products (good product rate 100%).
[0079]
Furthermore, the same plating solution as in Example 3 was used, and the vibration motor of the vibration flow generator 16 was vibrated at 38 Hz to perform copper plating. The film thickness uniformity of the plating film was good, and there was no defective product (non-defective product rate 100%).
[0080]
If the vibration flow generation part is stopped (that is, the generation of the vibration flow of the plating solution by the vibration flow stirring device is stopped), even if the barrel is vibrated, the occurrence of defects due to uneven plating film thickness is extremely large, and the yield rate is About 30%. Further, when the barrel vibration was stopped without stopping the vibration flow generating portion, the yield rate was about 60%.
[0081]
Example 5:
Same as Example 3 except that in the pretreatment of the surface of the ABS resin powder, instead of the treatment of accelerator (Sn removal) -water washing-chemical nickel plating for conductorization, conductor removal by Sn removal and Cu deposition is performed. Was processed. This is a method called direct plating.
[0082]
The synthetic resin powder having a copper plating film on the surface formed as described above has a copper plating film with good uniformity (non-defective product rate of 95%). As a result of inspection, it became clear.
[0083]
In the above embodiment, the interval between the anode metal member and the barrel is made close to about 40 mm to shorten the plating time and form a plating film with good film thickness uniformity to obtain a high yield rate. However, in the comparative example in which the operation of the vibration flow generation unit was stopped, if the distance between the anode metal member and the barrel was about 40 mm, burns and burns occurred, and high film thickness uniformity and high yield rate were obtained. There wasn't. When stopping the operation of the vibration flow generating part, the generation of burns and burns can be suppressed by increasing the distance between the anode metal member and the barrel to about 100 mm, but in that case, the plating time is long. It will take.
[0084]
【The invention's effect】
As described above, according to the barrel electroplating method of the present invention, it is possible to manufacture an extremely small article to be plated with good film thickness uniformity and a high film forming speed, and to improve the yield rate and productivity. Can be realized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of a plating apparatus in which a plating method of the present invention is performed.
FIG. 2 is a cross-sectional view showing a configuration of a plating apparatus in which the plating method of the present invention is performed.
FIG. 3 is a plan view showing a configuration of a plating apparatus in which the plating method of the present invention is performed.
FIG. 4 is an enlarged cross-sectional view of a portion where a vibration transmission rod is attached to a vibration member.
FIG. 5 is an enlarged cross-sectional view of a portion where a vibration blade is attached to a vibration transmission rod.
FIG. 6 is a view showing a modification of the attaching portion of the vibration blade to the vibration transmission rod.
FIG. 7 is a cross-sectional view showing a plating apparatus used for carrying out the plating method of the present invention.
FIG. 8 is a partially cutaway plan view of the plating apparatus of FIG.
FIG. 9 is a graph showing changes in plating current flowing through the article to be plated.
FIG. 10 is a cross-sectional view showing attachment of a vibration flow generating portion constituting a plating apparatus used for carrying out a plating method according to the present invention to a plating tank.
FIG. 11 is a cross-sectional view showing attachment of a vibration flow generating portion constituting a plating apparatus used for carrying out a plating method according to the present invention to a plating tank.
FIG. 12 is a plan view showing attachment of a vibration flow generating portion constituting a plating apparatus used for carrying out a plating method according to the present invention to a plating tank.
FIG. 13 is a plan view of a laminated body.
FIG. 14 is a cross-sectional view showing a state in which the upper part of the plating tank is blocked by a laminate.
FIG. 15 is a view showing a laminated body.
[Explanation of symbols]
12 Plating tank
14 Plating bath
16 Vibration flow generation part
16a base
16b Coil spring
16c vibration member
16d vibration motor
16e Vibration transmission rod
16f vibrating blade
16g1, 16g2 vibration stress dispersion member
16h1, 16h2 washers
16i1, 16i2; 16i3, 16i4 nut
16j Vibrating blade fixing member
16k spacer ring
16m, 16n nut
16p elastic member sheet
34 Power supply circuit
44 Vibration frame
46 Coil spring
48 Vibration motor
49 Balance Weight
50 Barrel support member
52 barrels
52a Pipe member
54 Cathode conductive member
54 ', 56' insulation coated wiring
56 Anode metal member
X Article to be plated

Claims (6)

A plurality of articles to be plated are accommodated in a barrel having a large number of small holes through which a plating solution can pass, and the barrel is moved in a plating bath while being arranged in contact with the article to be plated in the barrel. A barrel electroplating method of forming a plating film on the surface of the article to be plated by applying a voltage between the cathode member and the anode member disposed in the plating bath outside the barrel,
The article to be plated has an average diameter of 5 to 500 μm,
The diameter of the small hole in the barrel is 3 to 300 μm,
A vibration blade fixed in one or more stages to a vibrating rod that vibrates in the plating bath linked to vibration generating means has an amplitude of 0.1 to 10.0 mm and a vibration frequency of 200 to 800 times / minute in the plating bath. Barrel electroplating of a small article characterized by generating vibration flow in the plating bath by vibrating and vibrating the barrel at an amplitude of 0.1 to 5.0 mm and a frequency of 100 to 300 times / minute. Method. The barrel electroplating method according to claim 1 , wherein the vibration flow of the plating bath has a three-dimensional flow rate of 150 mm / second or more. A plurality of articles to be plated are accommodated in a barrel having a large number of small holes through which a plating solution can pass, and the barrel is moved in a plating bath while being arranged in contact with the article to be plated in the barrel. A barrel electroplating method of forming a plating film on the surface of the article to be plated by applying a voltage between the cathode member and the anode member disposed in the plating bath outside the barrel,
The article to be plated has an average diameter of 5 to 500 μm,
A vibration blade fixed in one or more stages to a vibrating rod that vibrates in the plating bath linked to vibration generating means has an amplitude of 0.1 to 10.0 mm and a vibration frequency of 200 to 800 times / minute in the plating bath. By vibrating, a vibration flow is generated in the plating bath. The vibration flow of the plating bath has a three-dimensional flow rate of 150 mm / second or more, and the barrel has an amplitude of 0.1 to 5.0 mm and a vibration frequency of 100 to 300. A method for barrel electroplating of an extremely small article , characterized by vibrating at times / minute . The barrel electroplating method according to any one of claims 1 to 3, wherein the article to be plated is made of a metal or a synthetic resin or a ceramic subjected to a conductor treatment. The barrel electroplating method according to claim 1 , wherein the movement of the barrel is a rotation movement around a rotation center in a non-vertical direction.   The barrel electroplating method according to claim 1, wherein the vibration generating means vibrates at 10 to 500 Hz.

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