JP4376575B2 - Method for producing plating-coated member - Google Patents

Description

  The present invention relates to a method for producing a plating-coated member having an electroless plating film. The manufacturing method of the present invention can be used for manufacturing decorative articles, circuit boards used in vehicles, information equipment, and the like.

  An electroless plating process is known as a method for imparting conductivity and metallic luster to a resin material that is a nonconductor. This electroless plating is a method in which metal ions in a solution are chemically reduced and deposited to form a metal film on the surface of the material. Unlike electrolytic plating in which electrolytic deposition is performed by electric power, metal such as resin is also applied to the insulator. A film can be formed. In addition, the resin material on which the metal coating is formed can be electroplated, and the application is expanded. For this reason, electroless plating is widely used as a method for imparting metallic luster or conductivity to resin materials used in fields such as automobile parts and home appliances.

  However, the plating film formed by the electroless plating process has a problem that it takes time until the film is formed or the adhesion of the film to the resin material is insufficient. For this reason, first, a chemical etching process is first performed on the resin material to roughen the surface, and then a process of electroless plating is generally performed. However, in the method of roughening by etching, it is necessary to use poisonous and deleterious substances such as chromic acid, permanganic acid and sulfuric acid, which causes a problem in waste liquid treatment.

  Thus, for example, in WO 03-021005, a polar group is formed on the surface of a non-conductive product by irradiating light in a state where the non-conductive product is immersed in a liquid in which semiconductor powder is suspended. A method of applying electroless plating to the formed surface is described. According to this method, the non-conductive surface is oxidized by the photoelectrochemical reaction of the semiconductor powder, and the polar group in the suspension is imparted to the non-conductive product surface to form the polar group there. Therefore, the adhesion of the plating film is improved by the chemical bond with the surface of the non-conductor product.

However, the method described in WO 03-021005 has a problem in that sufficient adhesion strength cannot be obtained unless the light irradiation time is lengthened, resulting in a problem in productivity.
WO 03-021005

  The present invention has been made in view of such circumstances, and it is an object to improve the productivity by developing strong adhesion of an electroless plating film in a short time without using poisonous and deleterious substances. And

A feature of the method for producing a plating-coated member of the present invention that solves the above-described problem is that light is applied to at least a non-conductive surface while spraying a photo-catalyst solution containing a photo-catalyst on the non-conductive surface of a substrate having a non-conductive surface. A photocatalyst treatment step;
And an electroless plating step of performing electroless plating on at least the non-conductor surface of the substrate treated in the photocatalyst treatment step.

  Furthermore, it is desirable to perform an alkali treatment step in which an alkali solution containing at least an alkali component is brought into contact with at least the non-conductor surface between the photocatalyst treatment step and the electroless plating step. The alkaline solution preferably further contains at least one of an anionic surfactant and a nonionic surfactant.

  That is, according to the manufacturing method of the plating covering member of the present invention, since the strong adhesion of the electroless plating film can be expressed in a short time, productivity is greatly improved. Moreover, since the etching process with poisonous and deleterious substances becomes unnecessary, the problem of waste liquid treatment is avoided, and the surface smoothness of the base material is improved.

  In the method for producing a plating-coated member of the present invention, first, in the photocatalyst treatment step, at least a non-conductive surface in a state where the non-conductive surface of the base material and the photo-catalyst liquid that contains the photocatalyst and flows at least on the non-conductive surface are brought into contact with each other. Is irradiating light. As a result, a fresh photocatalyst always comes into contact with the nonconductive surface, so that it is considered that the nonconductive surface is effectively activated by the photoelectrochemical reaction and many polar groups are formed. Therefore, an electroless plating film having excellent adhesion strength can be formed even in a short time, and productivity is greatly improved.

  Examples of the nonconductor include resins such as polyolefin, epoxy, and ABS, rubber, ceramic, and glass. And as for a base material, what has the nonconductor surface which this nonconductor exposed to at least one part is used, and the material of parts other than a nonconductor surface is not ask | required.

  As the photocatalyst, it can be selected from titanium dioxide, zinc oxide, cadmium sulfide, gallium phosphide, silicon carbide, indium oxide, vanadium oxide and the like. Titanium dioxide is particularly preferred. This photocatalyst is powdered and used as a photocatalyst liquid suspended in a liquid. Water can be used as a standard solvent for the photocatalyst solution, but organic solvents such as alcohols can also be used, and a mixed solvent of water and an organic solvent may be used.

  The particle size of the photocatalyst powder is preferably in the range of 0.1 to 1000 μm. When the particle size is smaller than 0.1 μm, handling becomes difficult, and when the particle size is larger than 1000 μm, the degree of activation at the time of light irradiation becomes small, which is not practical.

  Moreover, when suspending photocatalyst powder in water, it is desirable to suspend 0.01g or more of photocatalyst powder with respect to 1 liter of water. If it is less than 0.01 g, it becomes difficult to develop an activation promoting effect on the surface of the nonconductor due to the catalytic action of the photocatalyst during light irradiation.

Visible light can be used as the irradiated light, but it is desirable to use ultraviolet rays that are effective in activating the photocatalyst and can directly activate a nonconductor such as a resin. This ultraviolet ray preferably has a wavelength of 310 nm or less, preferably 260 nm or less, and more preferably about 150 to 200 nm. The amount of ultraviolet irradiation is desirably 50 mJ / cm ² or more. As a light source capable of irradiating such ultraviolet rays, a low pressure mercury lamp, a high pressure mercury lamp, an excimer laser, a barrier discharge lamp, a microwave electrodeless discharge lamp, or the like can be used.

  The greatest feature of the present invention resides in that at least the non-conductor surface is irradiated with light in a state where the photocatalyst solution is flowing at least on the non-conductor surface. As a result, it is considered that a fresh photocatalyst always contacts the nonconductive surface in a state activated by light, and a large number of polar groups are formed on the nonconductive surface.

That is , as shown in the Examples, light is irradiated while spraying a photocatalyst solution at least on the surface of the nonconductor. In this way, the thickness of the photocatalyst solution is reduced, so that the attenuation of light before reaching the non-conductor surface is suppressed. Therefore, since the degree of activation of the photocatalyst increases along with the action of the flow of the photocatalyst solution, the adhesion of the electroless plating film is improved in a shorter time.

  Furthermore, it is also preferable to rotate the substrate at high speed while spraying the photocatalyst solution. The photocatalyst liquid spreads in a film shape on the surface of the base material by the rotation of the base material, and the thickness of the photocatalyst liquid can be further reduced. Moreover, since the flow rate of the photocatalyst solution is high, fresh photocatalyst is supplied more quickly. Due to these synergistic effects, the adhesion of the electroless plating film can be improved in a shorter time.

In the electroless plating process, the catalyst is first adsorbed on at least the non-conductive surface of the base material treated in the photocatalyst treatment process. As this catalyst, a catalyst used in conventional electroless plating treatment such as Pd ²⁺ can be used. In order to cause the catalyst to be adsorbed on the nonconductive surface, a solution in which catalyst ions are dissolved may be brought into contact with at least the nonconductive surface. Moreover, conditions, such as contact time and temperature, may be the same as before.

  Thereafter, an electroless plating process is performed as in the conventional case. The conditions of the electroless plating treatment, the metal species to be deposited, etc. are not particularly limited, such as Ni, Cu, Au, and Ag, and can be performed in the same manner as the conventional electroless plating treatment.

  In addition, it is desirable to perform the electroplating process which performs electroplating further after an electroless-plating process. Thereby, functions such as metallic luster or conductivity can be imparted.

  It is desirable to further perform an alkali treatment step in which an alkali solution containing at least an alkali component is brought into contact with at least the non-conductor surface between the photocatalyst treatment step and the electroless plating step. Alkali component has the function of solubilizing non-conductor surface in water at the molecular level, and removes the brittle layer on the surface to expose more polar groups, further improving the adhesion of electroless plating film . As this alkali component, what can melt | dissolve a nonconductor surface in a molecular level and can remove an embrittlement layer can be used, and sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. can be used.

  The alkaline solution preferably further contains at least one of an anionic surfactant and a nonionic surfactant. This surfactant is considered that the hydrophobic group is likely to be adsorbed to the polar group exposed on the surface, and can be adsorbed to most of the polar group. In the electroless plating step, when the surface on which the surfactant is adsorbed is brought into contact with the catalyst, the catalyst is considered to be adsorbed on the hydrophilic group of the surfactant adsorbed on the polar group. And by applying electroless plating treatment to the nonconductive surface where the catalyst is sufficiently adsorbed, it is considered that the surfactant is removed from the polar group and the plated metal is bonded to the polar group, and it has better adhesion An electroless plating film can be formed.

  As this surfactant, those having a hydrophobic group easily adsorbed to at least one polar group consisting of C═O and C—OH are used, and at least one of an anionic surfactant and a nonionic surfactant is used. One is used. With a cationic surfactant and a neutral surfactant, an electroless plating film cannot be formed, and it is difficult to achieve an effect. Examples of the anionic surfactant include sodium lauryl sulfate, potassium lauryl sulfate, sodium stearyl sulfate, and potassium stearyl sulfate. Examples of the nonionic surfactant include polyoxyethylene dodecyl ether.

  As the solvent of the alkaline solution, it is desirable to use a polar solvent, and water can be used as a representative, but an alcohol solvent or a water-alcohol mixed solvent may be used in some cases. In order to bring the alkaline solution into contact with at least the nonconductive surface, a method of immersing the base material in the alkaline solution, a method of applying the alkaline solution to at least the nonconductive surface, a method of spraying the alkaline solution on at least the nonconductive surface, etc. It can be carried out.

  The concentration of the surfactant in the alkaline solution is preferably in the range of 0.01 to 10 g / L. When the concentration of the surfactant is lower than 0.01 g / L, the adhesion of the electroless plating film is reduced. When the surfactant concentration is higher than 10 g / L, the surfactant is in an associated state on the non-conductive surface, and excess surfactant is present. Since it remains as an impurity, the adhesion of the electroless plating film is lowered. In this case, the excess surfactant may be removed by washing with water.

  The concentration of the alkali component in the alkaline solution is preferably 12 or more in terms of pH value. The effect can be obtained even if the pH value is less than 12, but since there are few polar groups to be exposed, it takes a long time to form the electroless plating film by a predetermined film thickness.

  The contact time between the alkaline solution and the nonconductor surface is not particularly limited, but is preferably 1 minute or more at room temperature. If the contact time is too short, the amount of the surfactant adsorbed on the polar group may be insufficient and the adhesion of the electroless plating film may be reduced. However, if the contact time becomes too long, the layer in which the polar group is exposed may dissolve and electroless plating may be difficult. About 1 to 5 minutes is sufficient. A higher temperature is desirable, and the higher the temperature, the shorter the contact time can be. However, room temperature to about 60 ° C. is sufficient.

  In the alkali treatment step, the surfactant may be adsorbed after treatment with an alkali solution containing only an alkali component, but an embrittlement layer may be formed again until the surfactant is adsorbed. It is desirable to carry out the reaction in a state where at least one of an anionic surfactant and a nonionic surfactant coexists with an alkali component.

  Moreover, it is preferable to perform an alkali treatment process after a photocatalyst treatment process, but depending on the case, it is also possible to perform a photocatalyst treatment process and an alkali treatment process simultaneously. In this case, a mixed solution containing the photocatalyst powder and the alkali component is prepared, and the photocatalyst treatment step is performed using the mixed solution.

  In addition, you may perform the process of washing with water and removing an alkaline component after an alkali treatment process. Since the surfactant is strongly adsorbed on the polar group, it is known that the adsorbed state is maintained without being removed by washing with water. Therefore, even if time elapses before the electroless plating process, the effectiveness is not lost.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1
FIG. 1 shows a processing apparatus used in this embodiment. This processing apparatus includes a spinning stage 1 that is rotationally driven by a motor 10, a spray nozzle 2 that is disposed above the spinning stage 1, and an ultraviolet lamp 3 that is disposed above the spinning stage 1.

(1) Photocatalyst processing step First, the substrate 4 formed of ABS resin is placed on the spinning stage 1. Then, photocatalyst solution 5 in which 1.0 g / dm ^{3 of} titanium dioxide powder having an average particle size of 1.0 μm (anatase type) and 5% by weight of nitric acid is suspended and dissolved in water is adjusted to 25 ° C. and sprayed through pump 50. While spraying from the nozzle 2 onto the surface of the substrate 4 at a pressure of 0.08 to 0.2 MPa, simultaneously rotating the substrate 4 together with the spinning stage 1 at 50 to 1000 rpm, the ultraviolet lamp 3 irradiates ultraviolet rays with an irradiation intensity of 700 μW / cm ^2. did. This photocatalyst treatment was performed at three levels of 1 minute, 5 minutes, and 10 minutes to obtain respective treated substrates.

(2) Alkali treatment step Next, a mixed aqueous solution in which NaOH (alkali component) 50 g / L and sodium lauryl sulfate (anionic surfactant) 1 g / L are dissolved is heated to 60 ° C. and dried there. Each processed substrate was immersed for 2 minutes.

(3) Catalyst adsorption step After washing and drying these, 0.1% by weight of palladium chloride and 5% by weight of tin chloride were dissolved in 3N hydrochloric acid aqueous solution and immersed in a catalyst solution heated to 30 ° C. for 3 minutes, In order to activate palladium, it was immersed in a 1.5N hydrochloric acid aqueous solution for 3 minutes. As a result, a substrate on which the catalyst was adsorbed was obtained.

(4) Electroless Plating Step and Electrolytic Plating Step Thereafter, the substrate on which the catalyst was adsorbed was immersed in a Ni-P chemical plating bath kept at 40 ° C. to deposit 1 μm of the Ni—P plating film. Subsequently, a copper plating film was deposited to a thickness of 20 μm or more on the surface of the Ni-P plating film in a copper sulfate-based Cu electrolytic plating bath.

  After the formation of the copper plating film, it was dried at 70 ° C. for 2 hours. Then, the notch which reaches a board | substrate was made into the obtained copper plating film by 1 cm width, and the adhesion strength of the plating film was measured with the tension tester, respectively. The results are shown in Table 1.

(Example 2)
Photocatalytic treatment, alkali treatment, catalyst adsorption, electroless plating, and electrolytic plating were performed in the same manner as in Example 1 except that the substrate 4 formed of epoxy resin was used instead of the substrate 4 formed of ABS resin. went. Then, the adhesion strength of the plating film was measured in the same manner as in Example 1, and the results are shown in Table 1.

(Comparative Example 1)
An aqueous solution containing 1.0 g / dm ^{3 of} titanium dioxide powder having an average particle size of 1.0 μm (anatase type) and 5% by weight of nitric acid was adjusted to 25 ° C., and a substrate formed from the same ABS resin as in Example 1 4 was immersed, and the surface of the substrate 1 was irradiated with ultraviolet rays having an irradiation intensity of 700 μW / cm ² from an ultraviolet lamp 3 provided outside the aqueous solution. This photocatalyst treatment was performed at three levels of 1 minute, 5 minutes, and 10 minutes to obtain respective treated substrates.

  Thereafter, alkali treatment, catalyst adsorption, electroless plating, and electrolytic plating were performed in the same manner as in Example 1. Then, the adhesion strength of the plating film was measured in the same manner as in Example 1, and the results are shown in Table 1.

(Comparative Example 2)
Photocatalytic treatment was performed in the same manner as in Comparative Example 1 except that the substrate 4 formed of an epoxy resin was used instead of the substrate 4 formed of an ABS resin. Thereafter, alkali treatment, catalyst adsorption, electroless plating, and electrolytic plating were performed in the same manner as in Example 1. Then, the adhesion strength of the plating film was measured in the same manner as in Example 1, and the results are shown in Table 1.

  <Evaluation>

  From Table 1, according to the method of the example, the adhesion strength of 1000 gf / cm or more was obtained by the photocatalyst treatment for 10 minutes, whereas the adhesion strength was low in the comparative example, and the substrate formed from epoxy resin in particular. Adhesive strength is low when using. Therefore, it is clear that it is extremely effective to perform the photocatalytic treatment while flowing the photocatalytic liquid on the substrate surface.

It is explanatory drawing of the processing apparatus used for the manufacturing method of the plating covering member of one Example of this invention.

Explanation of symbols

1: Spinning stage 2: Spray nozzle 3: UV lamp 4: Substrate (base material) 5: Photocatalyst solution

Claims (4)

A photocatalyst treatment step of irradiating at least the nonconductor surface with light while spraying the photocatalyst solution containing the photocatalyst onto the nonconductor surface of the substrate having the nonconductor surface ;
An electroless plating step of performing electroless plating on at least the non-conductive surface of the substrate treated in the photocatalyst treatment step. The said photocatalyst processing process is a manufacturing method of the plating coating member of Claim 1 performed while rotating the said base material. The plating covering member according to claim 1 or 2 which further performs an alkali treatment process which makes an alkaline solution containing at least an alkaline ingredient contact at least said non-conductor surface between said photocatalyst processing process and said electroless plating process. Manufacturing method. The method for producing a plating-coated member according to claim 3, wherein the alkaline solution further contains at least one of an anionic surfactant and a nonionic surfactant.

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