JP5858428B2 - Partial plating apparatus and partial plating method - Google Patents

Description

  The present invention relates to an apparatus and method for partial plating, and more particularly to an apparatus and method for wet plating a portion of an object to be plated using a foam of a plating solution.

  Conventionally, when wet plating only a part of an object to be plated, there is a method in which a part of the object to be plated is covered by various methods and only the part to be plated is in contact with the plating solution. It is common. For example, when plating is performed only on the surface of a tubular object, the coating is performed by a technique such as preventing a plating solution from entering the inside of the tube with a rubber stopper. In addition, if the rod-shaped part of an object is not plated, and only the other part is plated, a coating method such as inserting a polyvinyl chloride or rubber tube into the part not subjected to the rod-shaped plating is possible. is there. The coating using a tube is often performed when only a part of a rod-shaped object is plated or when only the inside of a tubular object is plated.

  When plating only a part of a flat surface or curved surface, or when plating inside a branched tube, such a covering method using a plug or tube cannot be applied. For this purpose, a technique is used in which a coating such as paraffin or paint is applied to a portion that is not plated, or is covered with a sealing material. However, when such a coating is used, it takes time to remove it after plating. As the coating material, paraffin and paint are commonly used, but there is a problem that it is particularly troublesome to remove these cleanly. Further, when the temperature rises during the plating process, the paraffin is melted or the coating film is peeled off, so that the coating becomes incomplete, and the plating is performed on the surface other than the target portion to be plated.

  When performing partial plating using a sealing material, generally, a portion of the object to be plated is covered with the sealing material via an adhesive. In the plating process, the temperature of the plating solution is set to a temperature higher than room temperature, and the plating solution is often made uniform by stirring or the like. Decreases, the sealing material peels off, and a trouble called so-called plating leakage frequently occurs where plating is applied to the surface other than the target portion to be plated. This is a major problem of partial plating using a sealing material.

  In addition, as a method of partially plating an object to be plated such as a lead frame or a hoop material, conventionally, a covering material having an opening with a predetermined shape and the object to be plated are pressed against each other by a pressurizing means. A method for ejecting a plating solution from a nozzle is performed, and as a device for that purpose, circulation type partial plating equipped with a pressurizing means, nozzle, plating supply pipe, plating recovery pipe, plating solution reservoir, circulation pump, etc. Equipment has also been developed. However, in such a pressure type partial plating apparatus, since the plating solution is ejected vigorously from the nozzle, the object to be plated is subjected to a strong force at the opening, and the vicinity of the opening in the apparatus is not covered with the plating solution. It becomes a high pressure state by the supply pressure. As a result, even if a pressurizing means for pressure welding is applied, a decrease in the adhesion of the coating material to the object to be plated is unavoidable, and a product defect due to plating leakage is a major problem.

  In recent years, in such a pressure type partial plating apparatus, regarding the problem of plating leakage, by changing the material of the coating material to improve the mask hardness and surface condition, or by changing the thickness of the coating material, Attempts have been made to improve the adhesion with the object to be plated, and a plating solution injection path that generates a suction force at the opening of the coating material by applying the principle of an aspirator (Patent Document 1), In addition to contrivance to improve the adhesion mechanism between the object to be plated and the coating material by improving the pressing mechanism of the pressing means against the object to be plated, an apparatus equipped with a plating solution recovery means by a suction pump has also been proposed (Patent Document) 2).

As described above, in the pressure type partial plating apparatus that ejects the plating solution, the plating leakage due to the pressure and high temperature of the ejected plating solution is sufficiently prevented, even though various devices have been made conventionally. It was not possible to deter. Another problem caused by jetting the plating solution is that defects in plating called pits and pinholes are likely to occur. Originally, pits and pinholes are a major problem in electroplating, and hydrogen gas bubbles generated by the decomposition of water adhere to the surface of the object to be plated, which prevents the deposition of plating from occurring on the adhesion part. It occurs when a dent is formed. Even if the plating solution is ejected for partial plating, minute bubbles are inevitably generated in the jet, and the generated bubbles are transported to the surface of the object to be plated and stay on the surface as well. Cause pinholes. In addition, when bubbles move around the surface of the object to be plated by the force of the jet flow, there will be places where current does not flow temporarily at the location where the bubbles move, so the plating thickness may change partially, There is also a problem that a defect called so-called uneven plating, in which the crystal structure changes partially, is caused.
From the above, there has been a strong demand for the development of a new partial plating apparatus that can achieve uniform partial plating with no plating leakage and uneven plating with high accuracy and at low cost.

JP 63-247392 A JP 2000-119893 A JP 2009-84671 A JP 2008-223059 A

As a method for suppressing the occurrence of pinholes, pits, and plating unevenness, the present inventors instead of immersing an object to be plated in a plating solution, instead of using a foam of a plating solution containing a surfactant. A technique called “foam plating method” has been developed in which plating is carried out by contact (Patent Documents 3 and 4). This method can reduce the amount of the plating solution used, and can also reduce the amount of the plating solution that needs to be processed after use.
An object of the present invention is to provide means for applying such a “foam plating method”, which is an excellent plating method, to partial plating. Specifically, it does not use a coating material or sealing material that causes plating leakage or plating unevenness, and does not require a pressurizing means such as a high-pressure jet pump or a suction pump. This is to provide a technique for realizing high and uniform partial plating.

  As a result of earnest research, the inventors have made a trial and error as to whether the “foam plating method” developed by the inventors can be applied to partial plating. As a result, the foam of the plating solution is caused to flow in the transfer pipe. We came up with the idea of developing a new device and providing an opening of a predetermined shape in a part of the transfer pipe. By simply exposing the object to be plated to the opening provided in the transfer pipe and without providing a special pressurizing device or suction device, the object can be achieved only by the pressure from the foam flowing in the transfer pipe. It is surprising that only a region to be obtained can be partially plated uniformly without unevenness. Obtaining such knowledge led to the completion of the present invention.

  According to the present invention, in the newly developed apparatus for moving the foam of the plating solution in the transfer pipe, an opening having a predetermined shape is provided in a part of the transfer pipe, and the portion for plating the object to be plated is the opening. There are provided a partial plating apparatus and a partial plating method by wet plating, wherein the partial plating is performed by a foam plating method in a foam flow.

  As wet plating, both electroplating and electroless plating can be performed by the apparatus and method of the present invention. In the case of electroplating, since the object to be plated becomes a cathode, the apparatus is provided with an anode and an energizing means for applying electricity.

The aspect of the present invention will be described in detail as follows.
[1] It has a tubular foam transfer tube having an opening of a predetermined shape, and a plating solution containing a surfactant is held inside at one end of the foam transfer tube, and the foam generation filter is located near the bottom. A wet plating apparatus for partial plating, provided with a foam generating part provided, and provided with a defoaming apparatus at the other end,
An apparatus is characterized in that a part of an object to be plated is exposed in the foam transfer tube at the opening and plated by contact with a foam of a plating solution transferred in the foam transfer tube.
[2] The apparatus according to [1], wherein an opening having a packing that allows a workpiece to be placed in accordance with the shape of the portion to be plated is provided.
[3] The apparatus according to [1] or [2], wherein the wet plating is electroplating and has a positive electrode installed in the vicinity of the opening.
[4] The apparatus according to [1] or [2], wherein the wet plating is electroless plating.
[5] In the opening provided in the middle of the tubular foam transfer tube through which the foamed plating solution continuously flows, only the target plating portion of the object to be plated is exposed in the foam transfer tube, and the flow of the foam A method of partial plating, wherein the plating is performed by exposure to a metal.
[6] The foam transfer pipe has a branch, and an object to be plated is installed through packing in an opening provided at the branch, and only the part to be plated is exposed in the foam transfer pipe. The method according to [5].
[7] The method according to [5] or [6], wherein the wet plating is electroplating, and electroplating is performed between a positive electrode installed in the vicinity of the opening and a portion to be plated.
[8] The method according to [5] or [6], wherein the wet plating is electroless plating.

  According to the present invention, the occurrence of plating leakage, pinholes, pits and plating unevenness is suppressed, and uniform partial plating can be applied to the object to be plated. Further, the step of sealing the object to be plated with the covering material and the step of removing the covering material after the plating treatment can be omitted. And, by bringing the plating solution foam into contact with the object to be plated, the amount of the plating solution used and the amount of the plating solution required after use can be reduced to about 1/5 of the usual wet plating. it can. Furthermore, the application of the plating solution high-pressure jet pump, the plating solution suction pump and the pressurizing means in the apparatus can be omitted, so that simple and low-cost partial plating can be realized. Therefore, the present invention achieves excellent partial plating in both finish and cost.

It is a figure which shows an example of the partial plating apparatus with which this Embodiment is applied. It is a figure which shows an example of the partial plating in the opening part of a foam transfer pipe. It is a figure which shows the 2nd example of the partial plating in the opening part of a foam transfer pipe | tube. It is a figure which shows the 3rd example of the partial plating in the opening part of a foam transfer pipe | tube. It is a figure which shows the 4th example of the partial plating in the opening part of a foam transfer pipe.

Hereinafter, the present invention will be described in more detail.
The wet plating in the present invention means either electroplating or electroless plating.
The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the invention. Also, the drawings used are used to describe the present embodiment and do not represent the actual size.

  The present invention is characterized in that partial plating is performed under normal pressure using a foamed plating solution. The foam used in practicing the present invention is an aggregate of bubbles, and its apparent density is 1/3 or less of the density of the solution used to create the foam. It is in a state where it can be separated and float on the solution surface. As such foam, for example, many surfactants are added to an electroplating solution or an electroless plating solution, and a large number of such bubbles are generated by sending gas to a filter having a large number of pores provided in these plating solutions. This is a foam aggregate formed by the bubbles of the bubbles floating on the solution. Although the foam generation method is not particularly limited, a method that can easily continue to the operation of feeding the generated foam into the transfer tube, such as sending gas into the solution through a filter, is preferable. "Bubble" refers to a minute part containing gas in a liquid, and is clearly distinguished from "foam" that floats on the liquid surface of the solution separately from the solution. It is.

In the present embodiment, the surfactant is added to the plating solution in order to sufficiently reduce the surface tension of the plating solution so that the plating solution can form foam. The addition is performed at least until the surfactant reaches a concentration that sufficiently covers the surface of the solvent of the plating solution and the surface tension of the plating solution is not greatly reduced.
Specifically, it is preferable to add the surfactant until the surface tension of the plating solution is equal to or less than (surface tension at the critical micelle concentration when the surfactant is added to the plating solution + 15 mN / m).

  In the present embodiment, plating is performed on the object to be plated using foam of a plating solution composed of bubbles having a diameter of 1 mm or less, preferably 0.5 mm or less, of a plating solution containing a surfactant. Here, the foam of the plating solution means an aggregate of bubbles having a diameter of 1 mm or less, preferably 0.5 mm or less. This is because if the bubble diameter of the plating solution is excessively large, the liquid film of the foam becomes thin and the electric resistance is large, which is disadvantageous in film formation in electroplating. The foam diameter at the time of foaming can be controlled by the surfactant concentration, the gas supply speed when foaming the plating solution, and the pore diameter of the filter. Moreover, the foam comprised from a more fine bubble can also be obtained by adding a predetermined shear deformation | transformation to the generated foam, and dividing a bubble. When the foam diameter is reduced by shearing force, the surfactant concentration can be reduced and the gas supply speed can be increased to increase the foam movement speed, reducing the environmental burden and removing hydrogen gas bubbles. Efficiency can be improved. In addition to the above method, a method using ultrasonic vibration to prepare fine foams can be used. In addition, when the gas supply rate is low or the pore diameter of the filter is small, the diameter of the bubbles constituting the foam tends to be small.

  On the other hand, when the effect of suppressing pits and pinholes is taken into consideration, it is desirable that the foam diameter of the plating solution is approximately the same as the diameter of hydrogen gas bubbles causing pits or pinholes, or larger than the gas bubbles. The size of the gas bubbles grows with the progress of plating, but generally has a diameter of 0.1 mm or less. When the bubble diameter is larger than the gas bubble (for example, the diameter is 4 times or more), the bubble takes in the gas bubble, and when the bubble size is the same (for example, the diameter is less than 1 to 4 times), the bubble flow Since the gas bubbles are swept away, the gas bubbles can be removed from the surface of the object to be plated in any case. However, since the plating solution of the present invention contains a surfactant, it is relatively difficult for bubbles in the foam to take in gas bubbles, and there is a limit in the ability to take in, and the quality of the plating. Considering that the gas bubbles should be removed as soon as possible in order to keep the gas bubbles small, it is desirable that the bubbles have a small diameter as long as the ability to push the hydrogen gas bubbles is maintained.

  When practicing the present technology, it is desirable to use a foam of a plating solution having a long life with a volume reduction rate in 10 seconds of 50% or less. When using short-life plating solution foam, the amount of plating solution that exists as a partition between the foam bubbles and in contact with the object to be plated becomes unstable. It becomes difficult to do.

  The volume reduction rate of the plating solution foam is determined by the following procedure. A tube for feeding gas is connected to a spherical glass filter having a pore diameter of 5 μm to 100 μm, and the glass filter is placed at the bottom of a glass graduated cylinder (capacity 500 ml or more) about twice the diameter of the spherical part. The sample solution is placed in a graduated cylinder until the liquid level is about 3 cm above the top of the sphere. Gas is fed into the glass filter through the gas feeding tube, and foam is formed on the liquid surface until the height reaches 10 cm. In this state, the supply of gas is stopped, the height of the upper end of the foam after 10 seconds is obtained, and the length at which the upper end of the foam is lowered from 10 cm is expressed as a percentage with respect to 10 cm to obtain the volume reduction rate. The pressure of the gas to be fed in is appropriately selected according to the area of the glass filter, the hole diameter, and the diameter of the resulting plating solution foam, but is usually 1 kPa to 100 kPa.

FIG. 1 schematically illustrates an example of a partial plating apparatus to which the present embodiment is applied. An opening 11 having a packing 10 matched to the shape of the portion to be plated is connected in the middle of the flow path of the tubular foam transfer tube 5 that is connected to the foam generating portion 7 and matches the shape of the portion to be plated with the object 9. FIG. 1 shows an example of a plating apparatus for partial plating in which an object to be plated can be installed in the opening 11 in accordance with the shape of the part to be plated. The plating object 9 is fixed to the opening 11 via the packing 10 with such a force that the foam 8 does not leak outside the foam transfer tube 5. In the state in which the object 9 to be plated is continuously flowing the foam 8 generated in the foam generating unit 7 through the flow path in the foam transfer tube 5, only the portion to be plated in the opening 11 is in the flow of the foam 8. Exposed and electroless or electroplated. In the case of electroplating, an electrode (positive electrode) is provided in the vicinity of the opening in the transfer tube and parallel to the opening, but this is not shown in the figure. The plating solution passes through the plating solution supply unit 1, the plating solution supply tube 3, the foam generation unit 7, the foam transfer tube 5, the defoaming device 12, the plating solution adjustment tank 13, and the plating solution transport tube 14 in order. And used repeatedly for partial plating. The component adjustment of the plating solution is performed in the plating solution adjusting tank 13 as necessary.
The cross-sectional shape of the foam transfer tube 5 can be appropriately changed according to the shape of the portion where the object 9 is plated. For example, when the portion to be plated is a flat surface, a foam transfer tube 5 having a square cross section (not limited to a square) and having an opening 11 on one or more side surfaces thereof is employed. When the portion to be plated is a curved surface, a foam transfer tube 5 having a side surface having a shape matching the curved surface and having an opening 11 in the side surface portion having a shape matching the curved surface is employed.
A gas (nitrogen gas or the like) for generating foam is guided from the gas supply unit 2 to the foam generation unit 7 through the gas supply pipe 4 and the foam generation filter 6. The gas supply amount is adjusted in the gas supply unit 2.
It is also possible to install a plurality of foam transfer pipes 5 in parallel. In this case, the plating solution supply unit 1, the gas supply unit 4, the defoaming device 12, the plating solution adjustment tank 13, and the plating solution transport tube A part or all of 14 and the like can be shared facilities.

  The apparatus for partial plating of the present invention is used as an electroless plating apparatus or an electroplating apparatus. In the case of an electroplating apparatus, a positive electrode is installed in the vicinity of the opening 11.

Examples of the embodiment of the partial plating according to the present invention are shown in FIGS. Each figure is typically shown as a cross-sectional view of the foam transfer tube 5 and the object 9 to be plated cut along a plane parallel to the foam 8 transfer direction. In each figure, the arrow indicates the direction in which the foam 8 flows in the foam transfer tube 5. Even in one foam transfer tube, the opening for partial plating is not limited to one place, and can be provided at a plurality of places, and the area of one opening can be determined appropriately according to the object to be plated. However, it is generally 0.1 to 10,000 cm ² , preferably 1 to 1,000 cm ² .
FIG. 2 shows an embodiment in which a part of the object 9 is partially plated in the opening 11 in the shape of the opening 11. In the drawing, the foam 8 is shown to be transferred obliquely with respect to the opening 11 and contact the object to be plated, but the angle between the direction of the flow path and the portion to be plated of the object 9 is arbitrary, It can be changed as appropriate. A mode in which the foam 8 transferred to the portion to be plated contacts vertically is also possible, but the foam 8 flows smoothly in the foam transfer tube 5 and is contacted from an oblique direction to some extent in order to perform plating without unevenness. It is desirable to do. It can be said that the contact angle is arbitrary in the embodiments of the present invention, such as FIGS.
FIG. 3 is a modification of the embodiment of FIG. 2 and shows an embodiment for plating a part of the surface of the object to be plated in the opening 11 in a pattern. A portion of the opening 11 that does not require plating can be appropriately covered with a covering 15 provided in the foam transfer tube 5.
FIG. 4 shows an embodiment in the case of plating the inner diameter of the pipe-shaped workpiece 9. In this case, the cross-sectional shape of the inner diameter of the workpiece 9 and the cross-sectional shape of the foam transfer tube 5 in the opening 11 are the same.
FIG. 5 shows an embodiment in the case where plating is performed on a portion of an object 9 to be plated that shows a three-dimensional shape, such as a tip of a rod or needle, or an end face of the rod. The foam transfer tube 5 is branched at the opening 11 and provided with an opening that matches the shape of the portion to be plated. The branched foam transfer pipe 5 can be joined again in the transfer path up to the end of the path or in any part of the defoaming device 12.

The present invention is characterized in that plating is performed by flowing a foamed plating solution through a flow path in a foam transfer tube and bringing the foam into contact with the portion to be plated. Therefore, what is necessary is just to use what added the surfactant of the density | concentration required in order to make the foam suitable for the plating by this technique to the plating solution containing the metal to deposit, and it is not limited to the plating solution itself. However, the plating solution which is the electrolytic solution used in the present embodiment can be as follows.
In the present embodiment, as a plating solution, for both electroless plating and electroplating, one or more kinds of metal salts, organic electrolytes, acids such as phosphoric acid, and various electrolytes such as alkaline substances are dissolved in a predetermined solvent. Used.
The solvent is not particularly limited as long as it is a polar solvent. Specific examples include water; alcohols such as methanol and ethanol; cyclic carbonates such as ethylene carbonate and propylene carbonate; linear carbonates such as dimethyl carbonate, ethyl methyl carbonate and diethyl carbonate, or a mixed solvent thereof. .

Preferably, a solvent containing water as a main component is used.
Various additives may be added to water, which is the main component of the solvent, in order to control the life of the foam of the plating solution. Examples of such additives include ethylene glycol or oligomers thereof, alcohols such as glycerin; cyclic carbonates such as ethylene carbonate and propylene carbonate; linear carbonates such as dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate. Is mentioned.
Also, for example, an anionic electrolyte such as polyacrylic acid; a cationic electrolyte such as polyethyleneimine; coumarin, saccharin (1,2-benzisothiazol-3 (2H) -one 1,1-dioxide) (10 mg / L), additives such as 2-butyne 1,4-diol (5 mg / L) and the like may be added.
It is preferable to add about 0.1 to 0.2% by weight of glycerin to the plating solution as a stabilizer for preventing changes in the apparent density of foam.

  The metal salt used for the electroless plating is appropriately selected in consideration of the metal to be deposited, the alloy, the composition of the composite system, and the like. Examples of the metal that can be reduced and precipitated by the reducing agent include Au, Ag, Cu, Ni, Pd, Ni, Sn, Co, and Cr. Examples of composite plating include nickel-tungsten, nickel-boron, nickel-PTFE, Ni-P, Ni-B-W, and the like. The present invention can be applied to any of these electroless platings.

  The plating solution used for electroless plating is usually an aqueous solution containing a metal salt, a complexing agent, a reducing agent, a pH adjusting agent, a stabilizer, an accelerator, a film improving agent and the like. For example, an electroless plating solution of copper is usually an aqueous solution containing Rochelle salt as a complexing agent, formaldehyde as a reducing agent, thiourea as an additive, and caustic soda as a pH adjusting agent in addition to copper sulfate. When plating thickly, EDTA is used as a complexing agent and 2,2-bipyridyl is used as a stabilizer. In addition, thiocyanic acid or inorganic cyan may be used as a stabilizer, and an ammonium salt or molybdate may be used as an accelerator for increasing the plating rate.

  The metal salt used for electroplating is appropriately selected in consideration of the type of metal, alloy, oxide, etc. to be deposited. Examples of metals that can be electrochemically deposited include Cu, Zn, Ga, As, Cr, Se, Mn, Fe, Co, Ni, Ag, Cd, In, Sn, Sb, Te, Ru, and Rh. , Pd, Au, Hg, Tl, Pb, Bi, W, Po, Re, Os, Ir, Pt, and the like.

  The plating solution for electroplating may contain one or more substances in addition to the above substances for the purpose of stabilizing the solution. Specifically, substances that form complex salts with precipitated metal ions, other salts to improve the conductivity of the electrolyte solution, stabilizers that prevent hydrolysis of the plating solution, and buffers that suppress fluctuations in the pH of the plating solution Examples thereof include materials, conductivity improvers, substances that help dissolve the cathode, substances that change the properties of the plating solution or the properties of the deposited metal, such as brighteners and stabilizers for mixed solutions containing two or more metals. For example, a Watt bath used for nickel plating is an aqueous solution composed of nickel sulfate, nickel chloride, boric acid and hydrochloric acid, and saccharin or the like is further added as a brightening agent depending on the purpose.

  Specific examples of the main component of the plating solution are as follows. For example, as the main component of the plating solution for depositing copper, crystalline copper sulfate and sulfuric acid, copper borofluoride and borofluoric acid, copper cyanide and sodium cyanide, copper pyrophosphate, potassium pyrophosphate and aqueous ammonia; nickel The main components of the plating solution for precipitation are nickel sulfate, ammonium chloride and boric acid, nickel sulfate, nickel chloride and boric acid, nickel sulfamate, nickel chloride and boric acid; Components include chromic acid and sulfuric acid, chromic acid, barium acetate and zinc acetate; the main components of the plating solution for depositing zinc are zinc sulfate, ammonium chloride, ammonium sulfate, boric acid, and dextrin, zinc oxide, cyanide And sodium hydroxide, and sodium hydroxide, zinc oxide and sodium hydroxide.

  The main components of the electrolyte solution for depositing cadmium are cadmium oxide, sodium cyanide, gelatin and dextrin; the main components of the plating solution for depositing tin are stannous sulfate, sulfuric acid, cresolsulfonic acid, β-naphthol and gelatin, potassium stannate and free caustic potash; the main components of the plating solution for depositing silver are silver cyanide and potassium cyanide; the main component of the plating solution for depositing gold is gold , Potassium cyanide, potassium carbonate and potassium hydrogen phosphate; as the main components of the plating solution for depositing platinum, chloroplatinic acid, dibasic ammonium phosphate and dibasic sodium phosphate, chloroplatinic acid and acetate; The main components of the plating solution in the case of depositing rhodium include concentrated sulfuric acid and rhodium, phosphoric acid and rhodium phosphate.

  The main component of the plating solution for depositing ruthenium is a ruthenium complex; the main component of the plating solution for depositing brass is cuprous cyanide, zinc cyanide, sodium cyanide and sodium carbonate; iron nickel The main components of the plating solution for depositing alloys are nickel sulfamate, ferrous sulfamate, and sodium acetate; the main components of the electrolyte solution for depositing tin-lead alloys are tin, lead, and free borofluoric acid. And peptone, tin, lead, free borofluoric acid and peptone; as the main components of the electrolyte solution when depositing iron-nickel alloy, nickel phosphate (nickel sulfamate, ferrous sulfamate and sodium acetate) deposits cobalt phosphorus In this case, the main components of the plating solution include cobalt chloride, phosphorous acid, and phosphoric acid. It is.

In the present embodiment, the concentration of the surfactant in the plating solution is usually 0.001% by weight or more, preferably 0.005% by weight or more. Moreover, it is 2.0 weight% or less normally, Preferably, it is 1.0 weight% or less. A particularly preferred example is 0.1 to 0.5% by weight. The reason why there is a suitable concentration range of the surfactant is as follows.
When the concentration of the surfactant in the plating solution is excessively low, a continuous bubble layer of the plating solution tends not to be formed. Moreover, when the density | concentration of surfactant in a plating solution is low, even if a foam arises, the defoaming speed | rate is large and the tendency for a foam to become unstable is recognized. On the other hand, when the concentration of the surfactant in the plating solution is excessively high, the plating solution becomes a gel and not only the fluidity is lowered but also the surfactant may be incorporated as an impurity in the plating film. . In addition, if the concentration of the surfactant in the plating solution is excessively high, the foam film is stable, so the bubbles on the hydrogen gas electrode are less likely to diffuse into the foam film, and pinhole and pit formation is suppressed. It shows a tendency to reduce the effect.

  In the present embodiment, the surfactant to be added to the plating solution is not particularly limited as the surfactant, and known anionic, nonionic, cationic, and zwitterionic surfactants are used. If necessary, at least one or more can be appropriately selected and used. Next, specific examples of the surfactant are shown below.

  Examples of the anionic surfactant include soap, α-olefin sulfonate, alkylbenzene sulfonate, alkyl sulfate ester, alkyl ether sulfate, phenyl ether sulfate, methyl taurate, sulfosuccinate. , Ether sulfonate, sulfated oil, phosphate ester, perfluoroolefin sulfonate, perfluoroalkylbenzene sulfonate, perfluoroalkyl sulfate, perfluorophenyl ether sulfate, perfluoromethyl taurate, Examples include sulfoperfluorosuccinate, perfluoroethersulfonate, lauryl sulfate, octyl sulfate, and the like. A surfactant having a linear hydrophilic structure and an even number of carbon atoms is preferred, and lauryl sulfate is particularly preferred.

  Examples of the cation of the salt of the anionic surfactant include sodium, potassium, calcium, tetraethylammonium, triethylmethylammonium, diethyldimethylammonium, tetramethylammonium and the like.

  Nonionic surfactants include, for example, C1-C25 alkylphenols, C1-C20 alkanols, polyalkylene glycols, alkylolamides, C1-C22 fatty acid esters, C1-C22 aliphatic amines, alkylamine ethylene oxide additions. , Arylalkylphenol, C1-C25 alkylnaphthol, C1-C25 alkoxylated phosphoric acid (salt), sorbitan ester, styrenated phenol, alkylamine ethylene oxide / propylene oxide adduct, alkylamine oxide, C1-C25 alkoxylated phosphoric acid ( Salt), perfluorononylphenol, perfluoro higher alcohol, perfluoropolyalkylene glycol, perfluoroalkylolamide, perfluoro fatty acid ester , Perfluoroalkyl amine oxide adduct, perfluoroalkyl amine oxide / perfluoro propylene oxide adduct, perfluoroalkyl amine oxide, and the like.

  Examples of the cationic surfactant include lauryl trimethyl ammonium salt, stearyl trimethyl ammonium salt, lauryl dimethyl ethyl ammonium salt, dimethyl benzyl lauryl ammonium salt, cetyl dimethyl benzyl ammonium salt, octadecyl dimethyl benzyl ammonium salt, trimethyl benzyl ammonium salt, Hexadecylpyridinium salt, laurylpyridinium salt, dodecylpicolinium salt, stearylamine acetate, laurylamine acetate, octadecylamine acetate, monoalkylammonium chloride, dialkylammonium chloride, ethylene oxide addition-type ammonium chloride, alkylbenzylammonium chloride, tetramethylammonium chloride , Trimethylph Sulfonyl chloride, tetrabutylammonium chloride, acetate monoalkyl ammonium, and the like.

  Furthermore, imidazolinium betaine, alanine, alkylbetaine, monoperfluoroalkylammonium chloride, diperfluoroalkylammonium chloride, perfluoroethylene oxide addition type ammonium chloride, perfluoroalkylbenzylammonium chloride, tetraperfluoromethylammonium chloride , Triperfluoromethylphenylammonium chloride, tetraperfluorobutylammonium chloride, monoperfluoroalkylammonium acetate, perfluoroalkylbetaine and the like.

  Examples of the zwitterionic surfactant include a sulfated or sulfonated adduct of a condensation product of betaine, sulfobetaine, aminocarboxylic acid, ethylene oxide and / or propylene oxide and an alkylamine or diamine.

  From the gas supply part 2, air or an inert gas is supplied. In the embodiment of the present invention, as long as the plating solution can be foamed, the type of air or inert gas is not limited, but nitrogen gas, which is an inert gas, is preferable, and air is preferable. . The following describes nitrogen gas as an example.

  The supply of nitrogen gas is regulated by a pressure regulating valve, a flow regulating valve and a flow meter, and is led from the gas supply unit 2 through the gas supply pipe 4 to the foam generation filter 6 provided near the end of the foam transfer pipe 5. It is burned.

  The foam generation filter 6 is installed in the foam generation unit 7. The material forming the foam generation filter 6 is not particularly limited as long as it is not eroded by the plating solution. Examples thereof include glass and stainless steel. The pore diameter of the foam generation filter 6 is usually 1 mm or less, preferably 0.1 mm or less. However, it is usually 0.001 mm or more, preferably 0.01 mm or more.

The supply amount of nitrogen gas supplied to the foam generation unit 7 through the foam generation filter 6 can continuously supply the foam 8 of the plating solution to the portion to be plated exposed at the opening 11 of the foam transfer tube 5. The amount is not particularly limited as long as it is about a certain amount. However, if the moving speed of the plating solution foam in the transfer tube is too low, the supply of ions during plating will be insufficient and the possibility of uneven plating and scoring will increase, removing bubbles on the surface of the part to be plated. Since the effect of suppressing the generation of pits and pinholes also decreases, the amount of nitrogen gas supplied is preferably adjusted so that the speed of foam movement is 5 m / min or more. On the other hand, the smaller the gas flow rate introduced when forming the foam, the smaller the diameter of the foam, the thicker the liquid film of the plating solution, and the more stable the foam. Therefore, even if it is preferable that the foam moving speed is high, it is not simply an increase in the supply amount of nitrogen gas.
From the above circumstances, nitrogen gas is used so that the foam 8 has a moving speed in the vicinity of the opening in the foam transfer tube 5 of 5 to 50 m / min, preferably 10 to 40 m / min, and more preferably 15 to 30 m / min. Adjust the supply amount.
The foam generating part 7 is composed of a hydrophilic member whose inner surface is not eroded by the plating solution. An example is glass.

  By flowing the generated foam 8 through the foam transfer tube 5, the plating solution in the foam generating unit 7 is reduced. Therefore, in order to keep the plating solution held in the foam generating unit 7 at a constant amount, the reduced amount of solution is the plating solution. It is supplied from the supply unit 1 through the plating solution supply pipe 3. Unlike the prior art in which the plating solution is ejected at a high pressure toward the object to be plated, it is not necessary to supply the plating solution at a high pressure in the present invention. Therefore, even if a pump is used to supply the plating solution, A liquid supply pump is sufficient.

  The packing 10 that closes the gap between the workpiece 9 and the foam transfer tube 5 in the opening 11 is made of plastics such as a mixture of low-density polyethylene and high-density polyethylene, a crosslinked rubber, a thermoplastic elastomer, or a foam thereof. Select and use. It suffices to exhibit adhesiveness to the object 9 to be plated and to close the gap between the object 9 and the foam transfer tube 5. Unlike the method in which the plating solution is ejected onto the object to be plated, the foam plating method is performed under normal pressure, so that the packing 10 does not require high pressure resistance. The packing 10 has an elastic modulus of 1 GPa or less, preferably 700 MPa.

  The foam 8 in the flow path of the foam transfer tube 5 can be heated and kept warm from the outside as needed when the temperature for plating is not room temperature. As a part of the plating apparatus, it is preferable to provide a heat retention mechanism capable of keeping the foam 8 in the flow path at a temperature suitable for plating. As the heat insulation mechanism, a heat insulation agent, a heater, a jacket for circulating temperature-controlled water, and the like can be used. The temperature of the foam 8 is 40 ° C. to 70 ° C., preferably 45 ° C. to 60 ° C. when electroplating by heating. In the case of electroless plating, it is even higher, and it can be carried out by heating to 60 ° C to 90 ° C.

  The foam 8 that has passed through the portion to be plated 9 is guided to the defoaming device 12 that breaks the bubbles in the foam into a solution through the flow path in the foam transfer tube 5. The defoaming device 12 has an antifoaming filter for breaking the foam inside. The material forming the defoaming device 12 and the defoaming filter is not particularly limited as long as it is not eroded by the plating solution. The surface of the antifoaming filter is preferably formed of a hydrophobic plastic material such as PP, PE, PS, PMMA, or PTFE. In particular, a fluororesin such as PTFE is preferable. Instead of the defoaming filter, a stirring blade formed of a material having a fluororesin such as PTFE as a hydrophobic surface may be provided inside the defoaming device 12 and rotated to break the foam. Since the foam is broken by physical means in this way, the components of the plating solution are not modified even after the defoaming step, so that the plating solution that has gone through the apparatus can be recycled and used as it is.

  The foam 8 is returned to the solution by the defoaming device 12 and stored in the plating solution adjusting tank 13. The solution returned from the foam is subjected to filtration and composition adjustment as necessary for reuse. Although the adjustment can be performed in the plating solution adjustment tank 13, the adjustment is performed separately, and the plating solution adjustment tank 13 can be used exclusively for storing the plating solution. In order to drain the used plating solution, a drainage pipe for transferring the plating solution from the drainage storage tank and the plating solution adjustment tank to the drainage storage tank may be provided as a part of the apparatus.

  The material for forming the plating solution adjusting tank 13 and the plating solution supply unit 1 is not particularly limited as long as it is a material that is not eroded by the plating solution that is the electrolyte solution. Usually, glass etc. are mentioned.

  The materials for forming the plating solution supply pipe 3, the foam transfer tube 5 and the plating solution transport pipe 14 are not particularly limited as long as they are materials that are not eroded by the plating solution which is an electrolyte solution. Usually, stainless steel or glass tubes are used.

  The electroless plating conditions in the electroless plating method and the electroplating conditions in the electroplating method used in the embodiments of the present technology are appropriately selected depending on the type of metal for electroless plating or electroplating and the composition of the plating solution. There is no particular limitation. For example, in the case of nickel plating using a Watt bath, the concentration of the plating solution to be used is usually 260 g / l to 490 g / l, preferably 300 g / l to 400 g / l. Moreover, pH of a plating solution is 1.5-5.0 normally, Preferably, it is 3.0-4.8. The temperature of electroplating is 40 to 70 degreeC normally, Preferably, it is 45 to 60 degreeC.

  In the apparatus of the present invention, a cleaning liquid supply port is provided on the wall surface of the foam generating unit 7, and a cleaning liquid recovery port is provided between the foam transfer pipe 5 and the defoaming apparatus 12. It is possible to build it so that it can also be used. In this case, a lid that can be opened and closed is provided on the plating solution supply pipe 3 and the defoaming device 12 so that the composition of the plating solution and the foam of the plating solution is not changed by mixing of the cleaning solution, and during the cleaning with the cleaning solution, respectively. Close the lid.

  Pretreatment necessary for plating can also be performed using the flow path of the foam transfer tube 5. Pre-treatment of plating consists of washing with water, degreasing, removal of the oxide film on the surface, etc., but some or all of the liquid used for these may be used as a foam, or pre-treatment may be performed as it is. .

  In the electroplating method to which the present embodiment is applied, alloy plating can be performed to improve the color tone, magnetism, bondability, and conductivity of the plating film. Examples of the alloy plating that can be applied include an Au alloy, an Ag alloy, and a Cu alloy. Furthermore, Ni-P, Co-Mo, Co-Ti, Fe-Mo, etc. are mentioned.

  The electroplating method to which the present embodiment is applied includes, for example, electrochemical surfaces such as anodic oxide film formation, electrolytic polishing, electrolytic processing, electrophoretic coating, electrolytic refining, and chemical conversion treatment in addition to electroplating of metal members. Applicable to processing.

  In the electroplating method to which this embodiment is applied, composite plating is performed by dispersing fine particles such as alumina and silicon carbide in the plating solution, and eutecting these fine particles in the plating metal. It is possible to improve wear resistance, lubricity, and corrosion resistance. The fine powder used in the composite plating is not particularly limited, and any fine powder used in normal composite plating can be used.

Specific examples of the fine particles include, for example, metal oxides such as Al ₂ O ₃ , TiO ₂ , and SiO ₂ ; carbon compounds such as diamond, SiC, TiC, WC, and graphite; corundum; and polymer powder such as PTFE. Is mentioned. The present invention can be applied to electroless plating of any of these metals or alloys.

EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited at all by these Examples.
Other terms and concepts in the present invention are based on the meanings of terms conventionally used in the field, and various techniques used for carrying out the present invention include those that clearly indicate the source. Except for this, it can be easily and reliably carried out by those skilled in the art based on known documents and the like. Moreover, the description content in the technical literature, the patent gazette, and the patent application specification quoted in this specification shall be referred as description content of this invention.
In the examples and comparative examples, all parts and% are based on weight unless otherwise specified.

(1) Object to be plated A 4cm x 6cm x 0.1cm aluminum plate was washed with detergent, electrolytic degreased and alkaline degreased for 5 minutes each, and ultrasonically washed in pure water for 5 minutes, then with a foam flow The test piece to be plated is plated as it is, and the test piece to be electroplated in solution is the same as the test piece to be electrolessly plated in solution, using a corrosion-resistant tape manufactured by Sumitomo 3M Co., Ltd. The plating was performed by masking leaving a portion of × 3 cm.

(2) Electroless plating solution For plating of the masked test piece, a solution obtained by dissolving nickel electroless plating solution manufactured by Okuno Pharmaceutical Co., Ltd., Top Nicolon F-153A in 100 mL with respect to 1 L of water was used. When plating was performed using a flow, a surfactant obtained by adding 0.1 wt% sodium lauryl sulfate as a surfactant was used.

(3) Electroplating solution In 1000 parts of water, 240 parts of nickel sulfate, 45 parts of nickel chloride and 30 parts of boric acid are dissolved, and a brightener (Akuna NCF-MU manufactured by Okuno Pharmaceutical Co., Ltd.) is added to adjust the pH to 4-5. The prepared solution was used for plating a masked test piece. Moreover, when plating using the flow of foam, what added 0.1 wt% of sodium lauryl sulfate as a surfactant to the plating solution of this composition was used.

(4) Experimental apparatus In the case of plating in a solution, the plating solution was kept at a predetermined temperature and plating was performed with sufficient stirring.
When plating is performed using a foam flow, the liquid level in the foam generating part is kept constant, and a stainless steel filter having an effective length of 5 cm and a pore diameter of 20 μm is installed at the bottom of the foam generating part. Then, air is sent to the foam generating filter at a flow rate of 0.4 L / min, and the foam generated here is sent to the flow path in the foam transfer tube facing diagonally upward. Here, the diameter of most of the bubbles is 0.4 mm or less, the average diameter is about 0.2 mm, and the volume reduction rate of the generated foam for 10 seconds is 50% or less. This flow path becomes horizontal in the rectangular flow path at a position where the length of the foam layer is about 10 cm, and thereafter is directed obliquely downward to guide the foam to a defoaming device for liquefying the foam. There is an opening of 2cm x 3cm in the upper part of the horizontal part, and a packing material made of a material in which 10% by weight of high-density polyethylene is mixed with ethylene / propylene-based thermoplastic elastomer matched to the size of the opening is installed. Yes. After lightly pressing the part to be plated here, foam is generated, and the foam is plated in a state where the part to be plated is exposed to the flow of foam at a flow rate of 5 m / min or more. Do.
In the case of electroplating, plating was performed at a current density of 2 A / dm ² using a 2 cm × 2 cm nickel plate below the horizontal portion and an anode and a constant current power source.

(5) Example 1
The test piece prepared before is pressed against the opening of the foam channel, the plating solution and foam temperature are kept at 85 ° C., and after electroless plating for about 1 hour, the test piece Washed with water and dried. Although plating was performed 10 times, no plating leakage was observed in any of the test pieces, and plating according to the shape of the opening was performed. There was almost no thickness unevenness in the plated part, and it showed a beautiful metallic luster. Also, no pits or pinholes were observed, and the generation of pits and pinholes was clearly suppressed as compared with the case of the following comparative example.

(6) Example 2
Press the unmasked test piece prepared earlier against the opening of the foam channel to keep the plating solution and foam temperature at 50 ° C., and perform electroplating at a current density of 2 A / dm ² for about 15 minutes. After the test, the test piece was washed with water and dried. Although plating was performed 10 times, no plating leakage was observed in any of the test pieces, and plating according to the shape of the opening was performed. In the plated portion, the thickness unevenness was as good as about ± 7% and showed a beautiful metallic luster. Also, no pits or pinholes were observed, and the generation of pits and pinholes was clearly suppressed as compared with the following comparative example.

(7) Comparative Example 1
The masked test piece prepared previously was subjected to electroless plating at 85 ° C. for about 1 hour while sufficiently stirring the electroless plating solution, and then the test piece was washed with water and dried. Plating was performed 10 times. The central 2 cm × 3 cm portion was finely plated, but all of the test pieces had almost no masking, and the portion was also mottled. In addition, there were three specimens with pinholes observed slightly.

(8) Comparative Example 2
The previously prepared masked test piece was electroplated at 50 ° C. for about 15 minutes while sufficiently stirring the electroplating solution, and then the test piece was washed with water and dried. Plating was performed 10 times. The central 2 cm × 3 cm portion was finely plated, but in each test piece, the masking around this portion was partially peeled off, and the portion where the masking was peeled was also mottled. The thickness unevenness was about ± 15%, the gloss was slightly dull, and several pinholes were observed in all the test pieces.

1: Plating solution supply unit 2: Gas supply unit 3: Plating solution supply tube 4: Gas supply tube 5: Foam transfer tube 6: Foam generation filter 7: Foam generation unit 8: Foam 9: Plated object 10: Packing 11: Opening 12: Defoaming device 13: Plating solution adjusting tank 14: Plating solution transport pipe 15: Covering material

Claims (8)

A foam having a tubular foam transfer pipe having an opening of a predetermined shape, and having a foaming filter in the vicinity of the bottom while holding a plating solution containing a surfactant at one end of the foam transfer pipe. A wet plating apparatus for partial plating in which a generating part is provided and an antifoaming apparatus is provided at the other end, wherein the wet plating is electroless plating,
An apparatus is characterized in that a part of an object to be plated is exposed in the foam transfer tube at the opening and plated by contact with a foam of a plating solution transferred in the foam transfer tube. A foam having a tubular foam transfer pipe having an opening of a predetermined shape, and having a foaming filter in the vicinity of the bottom while holding a plating solution containing a surfactant at one end of the foam transfer pipe. A wet plating apparatus for partial plating in which a generating part is provided and an antifoaming apparatus is provided at the other end,
The opening is included in a side surface of the foam transfer tube,
A part of the object to be plated is exposed in the foam transfer pipe at the opening, and is plated by contact with the foam of the plating solution transferred in the foam transfer pipe,
It is characterized by being provided with an opening having a packing that allows the object to be plated to be installed according to the shape of the part to be plated ,
The packing is selected from plastics, crosslinked rubber, thermoplastic elastomer, and foams thereof, and the elastic modulus is 1 GPa or less,
Equipment that does not use a covering or sealing material .   The apparatus according to claim 2, wherein the wet plating is electroplating and has a positive electrode installed in the vicinity of the opening. A foam having a tubular foam transfer pipe having an opening of a predetermined shape, and having a foaming filter in the vicinity of the bottom while holding a plating solution containing a surfactant at one end of the foam transfer pipe. A wet plating apparatus for partial plating in which a generating part is provided and an antifoaming apparatus is provided at the other end,
The said foam transfer pipe has a branch, The said opening part is provided in the part of this branch , The apparatus characterized by the above-mentioned. In the opening provided in the middle of the tubular foam transfer tube through which the foamed plating solution continuously flows, only the target plating portion of the object to be plated is exposed in the foam transfer tube and exposed to the flow of foam. A partial plating method by wet plating in which plating is performed by
A method wherein the wet plating is electroless plating . In the opening provided in the middle of the tubular foam transfer tube through which the foamed plating solution continuously flows, only the target plating portion of the object to be plated is exposed in the foam transfer tube and exposed to the flow of foam. A partial plating method by wet plating in which plating is performed by
The foam transfer pipe has a branch, and an object to be plated is installed through packing in an opening provided in the branch part, and only a portion to be plated is exposed in the foam transfer pipe. ,Method. In the opening provided in the side surface in the middle of the tubular foam transfer tube through which the foamed plating solution continuously flows, only the target plating portion of the object to be plated is exposed in the foam transfer tube, and the flow of foam It is a partial plating method by wet plating in which plating is performed by being exposed,
Here, the object to be plated is pressed against the packing without using a covering material or a sealing material, and the packing is selected from plastics, a crosslinked rubber, a thermoplastic elastomer, and a foamed material thereof. A method having an elastic modulus of 1 GPa or less . The method according to claim 7 , wherein the wet plating is electroplating, and electroplating is performed between a positive electrode and a portion to be plated that are installed in the vicinity of the opening .