JP2007231362A - Electroless plating method of resin product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electroless plating method of a resin product, by which the pretreatment time for electroless plating can be shortened, the adhesion between a plated layer and the surface of the resin product can be improved, and the variation in the adhesion between the plated layer and the surface of the resin product can be reduced. <P>SOLUTION: The electroless plating method comprises, after irradiating the resin product with an ultraviolet ray in the atmosphere, (1) dipping the resin product into a suspension liquid of a semiconductor powder, then irradiating the resin product with light in the suspension liquid to form polar groups on the surface of the resin product, and applying electroless plating on the surface, on which the polar groups are formed, of the resin product, or (2) irradiating the resin product with an infrared ray through water or an aqueous solution and thereafter, applying electroless plating on the surface of the resin product. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a resin that can shorten the pretreatment time during electroless plating, has good adhesion between the surface of the resin product and the electroless plating layer, and can improve variation in adhesion. The present invention relates to a method for electroless plating of products.

  Known methods for imparting conductivity and metallic luster to resin products include a method of depositing a metal on a resin product in a vacuum, a method of sputtering a metal, a method of electroless plating, and the like. Electroless plating refers to 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 electroplating, which is electrolytically deposited by electric power, a metal film is also applied to an insulator such as a resin. Can be formed.

  However, the plating film formed by the electroless plating treatment has a problem that the adhesion strength to the material surface is not sufficient. Therefore, in the case of electroless plating, it is necessary to pre-treat, for example, surface roughening to chemically etch the surface of the resin product, imparting polar groups, and catalyzing, A method of performing electroless plating is known.

  By the way, in Patent Document 1, a resin group is immersed in a liquid in which a semiconductor powder is suspended, and light is irradiated in the liquid to form a polar group on the surface of the resin product. A method for performing electroless plating on the surface and a method for performing electroless plating after irradiating with ultraviolet rays through water or an aqueous solution are described. According to this method, there can be obtained a plated product in which the plating layer and the resin product surface are in good contact with each other without problems such as environmental pollution and waste liquid treatment, which have been problems in the past.

  However, in this method, the pretreatment time can be shortened, the adhesion between the plating layer and the resin product surface can be further improved, and the variation in the adhesion between the plating layer and the resin product surface can be reduced. A plating method has been desired.

International Publication WO2003 / 021005 Panfred

  In view of such a situation, the problem of the present invention is that the pretreatment time for electroless plating can be shortened, and the adhesion between the plating layer and the resin product surface is good. An object of the present invention is to provide an electroless plating method for resin products, which can reduce the variation in adhesion.

In the present invention for solving the above-mentioned problems, first, after a resin product is treated by irradiating ultraviolet rays in the atmosphere, it is immersed in a liquid in which semiconductor powder is suspended, and light is irradiated in the liquid. By this, a polar group is formed on the surface of the resin product, and electroless plating is performed on the surface on which the polar group is formed.
Second, the resin product is treated by irradiating the resin product with ultraviolet rays in the atmosphere, and then treated by irradiating with ultraviolet rays through water or an aqueous solution, and then electroless plating is performed. The electroless plating method.

  According to the electroless plating method of the present invention, the pretreatment time for electroless plating can be shortened, the adhesion between the plating layer and the resin product surface is further improved, and the adhesion between the plating layer and the resin product surface is improved. The variation in sex can be reduced.

The present invention will be described in detail below.
(1) In the first invention, first, the resin product is treated by irradiating ultraviolet rays in the atmosphere, immersed in a liquid in which the semiconductor powder is suspended, and irradiated with light in the liquid. A polar group is formed on the surface of the resin product, and electroless plating is performed on the surface on which the polar group is formed.

  The resin constituting the resin product in the present invention is not particularly limited. For example, acrylonitrile-butadiene-styrene resin (ABS resin), polyimide resin, epoxy resin, polyethylene terephthalate resin (PET resin), and polystyrene resin (PS) Resin) and the like. Moreover, the shape is not limited at all, but may be a resin-molded one, for example, a plate shape, a spherical shape, a fine particle shape, or the like.

  The ultraviolet irradiation is performed at 20 to 100 ° C., preferably 40 to 60 ° C. in the atmosphere, and ultraviolet rays having a wavelength of 400 nm or less, preferably 185 to 260 nm. The irradiation time is 0.1 to 10 minutes, preferably 0.5 to 3 minutes. As a light source, a synthetic quartz lamp, a normal quartz lamp, an ozoneless lamp, or the like is used.

  After the ultraviolet irradiation treatment of the resin product, it is immersed in a liquid in which the semiconductor powder is suspended, and a polar group is formed on the surface of the resin product by irradiating light in the liquid. Then, the catalyst is applied and activated by a conventional method, and then electroless plating is performed.

  The semiconductor powder is a semiconductor powder having photoelectric polarity. Preferred examples of the semiconductor include titanium dioxide, zinc oxide, cadmium sulfide, gallium phosphide, silicon carbide, indium oxide, and vanadium oxide. More preferably, it is anatase type titanium dioxide.

  Further, the semiconductor powder can be used in any shape. The particle size of the powder is preferably 0.01 to 1000 μm, more preferably 0.01 to 10 μm, and still more preferably 0.01 to 5 μm. In particular, in the case of anatase type titanium dioxide, the particle size is preferably from 0.01 to 3 μm.

  The liquid for suspending the semiconductor powder preferably contains 0.005 to 99% by weight of the semiconductor powder. When the semiconductor powder contained is less than 0.005% by weight, polar groups may not be sufficiently formed on the non-conductor surface during the light irradiation treatment. If the semiconductor exceeds 99% by weight, it may be difficult to uniformly disperse the semiconductor. More preferably, it is 0.01 to 20% by weight.

  Further, the semiconductor powder may carry 0.01 to 10% by weight of a metal such as platinum or palladium with respect to the semiconductor. When a semiconductor powder carrying a metal such as platinum or palladium is used, a polar group is more effectively imparted to the surface of the resin product.

  The liquid for suspending the semiconductor powder used in this invention is an aqueous or non-aqueous liquid, and examples of the aqueous liquid for suspending the semiconductor powder include water, an aqueous sulfuric acid solution, an aqueous nitric acid solution, Those containing a sulfone group or a nitro group are preferred. The concentration of the sulfuric acid aqueous solution or nitric acid aqueous solution is preferably 0.01 to 99% by weight, and more preferably 0.01 to 20% by weight. Therefore, for example, when nitric acid is contained in the solution, the nitro group is imparted, and thus the stable resin surface becomes unstable, and the plating layer formed thereafter adheres firmly, which is preferable. Examples of non-aqueous liquids include alcohols and ethers.

  Moreover, you may add a photosensitizer to the liquid for suspending semiconductor powder so that it may become 1 to 50 weight% with respect to the whole liquid. By adding a photosensitizer, a polar group is effectively imparted to the surface of the resin product. Examples of the photosensitizer include ions of palladium, nickel, copper, iron, gold, platinum, etc. Among them, iron ions are preferable.

  The light to be irradiated is preferably ultraviolet light or visible light, and particularly preferably irradiated with ultraviolet light. Since the bond on the resin surface is cleaved by the ultraviolet light, the plating layer is stabilized. Ultraviolet light is also called ultraviolet light and means light having a wavelength of 4 to 400 nm. Visible light is also called visible light and means light having a wavelength of 400 to 750 nm. Examples of light sources include low-pressure mercury lamps, high-pressure mercury lamps, xenon lamps, tungsten lamps, halogen lamps, excimer lasers, and other lasers, barrier discharge lamps, dielectric barrier discharge lamps, microwave electrodeless discharge lamps, excessive discharge A lamp etc. can be mentioned.

  In this method, a polar group is formed on the surface of a resin product by immersing the resin product in a liquid in which semiconductor powder is suspended and irradiating light. The light irradiation time is appropriately selected depending on the type of resin product or semiconductor powder to be used, but is preferably 1 to 180 minutes. At this time, the surface of the resin product is oxidized by the photoelectrochemical reaction of the semiconductor powder, and the polar group in the suspension is added to the surface of the resin product to form the polar group, thereby significantly increasing the chemical bond. Thus, the adhesion with the plating film is strengthened. It is particularly preferable to irradiate a mercury lamp for 5 to 30 minutes. In order to remove the semiconductor powder adsorbed on the surface of the resin product when the light is irradiated, it is more preferable to perform ultrasonic vibration or the like at regular intervals.

Examples of the polar group formed on the surface of the resin product include a carbonyl group (C═O) and a carboxyl group (COOH). For example, when anatase-type titanium dioxide is used as the semiconductor powder, the reaction proceeds from a hydroxide radical generated by a chemical reaction with water, and a hydrophilic carbonyl group is formed on the surface of the resin product. Improves the wettability of the product surface. The polar group may be formed on the resin product surface by forming an arbitrary layer on the resin product surface by a conventional method, but it is preferably formed directly on the resin product surface.
Thereafter, electroless plating is performed on the surface of the resin product on which the polar group is formed in the same manner as the conventional electroless plating treatment.

(2) In the electroless plating method of the resin product according to the second invention, the resin product is treated by irradiating the resin product with ultraviolet rays in the atmosphere, and then treated by irradiating ultraviolet rays through water or an aqueous solution. Thereafter, electroless plating is performed in the same manner as the conventional electroless plating treatment.

  In order to perform the treatment by irradiating the resin product with ultraviolet rays in the atmosphere, the resin product described in (1) is used as described in (1). Thereafter, the resin product is irradiated with ultraviolet rays through water or an aqueous solution. When the resin product is irradiated with ultraviolet rays through water or an aqueous solution, the heat rays are first absorbed by the water or the aqueous solution, or the resin product is cooled by evaporation of the water, thereby preventing overheating of the resin product and preventing thermal deformation. be able to. Moreover, even if the irradiation amount of ultraviolet rays increases, there is no problem that the adhesion strength of a plating film falls. This is presumably because the surface of the resin is oxidized to some extent by the hydroxyl groups of water and activated.

  In order to irradiate the resin product with water or an aqueous solution after irradiating with ultraviolet rays in the atmosphere, at least the irradiated surface of the resin product is wetted with water or an aqueous solution, and then irradiated with ultraviolet rays. However, it is preferable to irradiate ultraviolet rays from the outside of the container while the resin product is immersed in water or an aqueous solution. In this way, a sufficient amount of water can be secured, so that the temperature rise of the resin product can be further suppressed and thermal deformation can be further prevented.

The ultraviolet rays irradiated through water or an aqueous solution can be used as long as they are electromagnetic waves in the ultraviolet region, but from the viewpoint of activating the surface of the resin product, electromagnetic waves having a wavelength in the range of 50 to 400 nm are used. It is preferably 380 nm or less, preferably 300 nm or less, and more preferably about 150 to 260 nm. Moreover, it is preferable that the irradiation amount of an ultraviolet-ray is 10 mW / cm < ² > or more.

  As such a light source capable of irradiating ultraviolet rays, a low pressure mercury lamp, a high pressure mercury lamp, an excimer laser, a barrier discharge lamp, a dielectric barrier discharge lamp, a microwave electrodeless discharge lamp, an excessive discharge lamp, or the like can be used. When the resin product is immersed in water or an aqueous solution and irradiated with ultraviolet rays, it is preferable to use a container that easily transmits ultraviolet rays, and it is particularly preferable to use a container made of transparent quartz.

  As the aqueous solution, an aqueous solution in which an oxidizing agent or an alkaline substance is dissolved is preferably used. If an aqueous solution in which an oxidizing agent or an alkaline substance is dissolved is used, activation of the resin surface by ultraviolet irradiation is promoted, so that the adhesion strength of the plating film is improved even if the irradiation amount of ultraviolet rays is reduced. Therefore, the amount of heat received by the resin product can be reduced, and thermal deformation can be further prevented. In order to reduce the irradiation amount of ultraviolet rays, the number of light sources may be reduced or the irradiation time may be shortened.

  Examples of the oxidizing agent include sodium perchlorate, potassium perchlorate, sodium peroxide, potassium peroxide, and hydrogen peroxide. Moreover, as an alkaline substance, sodium hydroxide, potassium hydroxide, etc. are preferable, but ammonia etc. can also be used depending on the case. The concentration of the oxidizing agent or alkaline substance in the aqueous solution is not particularly limited, but is preferably determined by trial and error according to the type of oxidizing agent or alkaline substance and the type of resin product.

  Furthermore, when the resin product is immersed in water or an aqueous solution and irradiated with ultraviolet rays, it is preferably performed while bubbling bubbles. In this way, since ultraviolet rays are diffusely reflected by bubbles, it is possible to irradiate the shaded part of the resin product, which is the blind spot of the irradiated ultraviolet optical axis, and high adhesion to the shaded part. A plating film having strength can be formed. The bubbles may be air, but it is also preferable to use an oxidizing gas such as ozone.

  The resin product after the ultraviolet treatment may be subjected to electroless plating as it is, but a solution containing at least one of an anionic surfactant and a nonionic surfactant and an alkali component is brought into contact with the resin product. It is preferable to perform processing. In this treatment, it is considered that the hydrophobic group is adsorbed on the polar group that appears on the surface of the resin product after the ultraviolet treatment. The alkali component has a function of dissolving the surface of the resin product at the molecular level, and removes the embrittlement layer on the surface of the resin product to expose more polar groups. Therefore, the surfactant is also adsorbed to the new polar group that is exposed by removing the embrittlement layer.

  As the surfactant, one having a hydrophobic group easily adsorbed to at least one polar group composed of C═O and C—OH is used, and at least one of an anionic surfactant and a nonionic surfactant is used. Is used. When a cationic surfactant and an amphoteric surfactant are used, a plating film may not be formed or it may be difficult to achieve the 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 and polyethylene glycol dodecyl ether.

  As an alkali component, what can melt | dissolve the surface of a resin product in a molecular level and can remove an embrittlement layer can be used, and sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. can be used.

  As the solvent of the solution containing the surfactant and the alkali component, it is preferable to use a polar solvent, and water can be representatively used. However, depending on the case, an alcohol solvent or a water-alcohol mixed solvent may be used. Good. The solution can be brought into contact with the resin product by a method of immersing the resin product in the solution, a method of applying the solution on the surface of the resin product, a method of spraying the solution on the surface of the resin product, or the like.

  The concentration of the surfactant in the 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 plating film is lowered. When the concentration is higher than 10 g / L, the surfactant is in an associated state on the surface of the resin product, and excess surfactant is an impurity. Therefore, the adhesion of the plating film is lowered. In this case, the resin product may be washed with water after the treatment to remove excess surfactant.

  Further, the concentration of the alkali component in the solution is preferably 12 or more in terms of pH value. Even if the pH value is less than 12, the effect can be obtained, but the number of polar groups to be exposed is reduced, the adhesion of the catalyst metal is lowered, and the formation of the plating film becomes difficult. The contact time between the solution and the resin product is not particularly limited, but is preferably 1 minute or longer 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 plating film may be reduced. However, if the contact time is too long, the layer where the polar group is exposed may be dissolved and electroless plating may be difficult, so about 1 to 5 minutes is sufficient. The temperature is preferably higher, and the higher the temperature, the shorter the contact time can be, but room temperature to about 60 ° C is sufficient.

  In this invention, the surfactant may be adsorbed after the treatment with the aqueous solution containing only the alkali component, but the embrittlement layer may be formed again until the surfactant is adsorbed. It is preferably carried out in a state where at least one of an ionic surfactant and a nonionic surfactant and an alkali component coexist.

  In addition, in this invention, you may perform the process of washing with water and removing an alkaline component after a 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, the effect of the treated resin product is not lost even if time elapses before the electroless plating treatment.

  In the electroless plating process, the resin product to which the surfactant is adsorbed is first brought into contact with the catalyst. Then, it is considered that the catalyst is adsorbed on the hydrophilic group of the surfactant adsorbed on the polar group. By applying electroless plating to a resin product that has sufficiently adsorbed catalyst, it is thought that the surfactant is removed from the polar group and the plating metal is bonded to the polar group. A film can be formed.

As the catalyst, a catalyst used for conventional electroless plating treatment such as Pd ²⁺ can be used. In order to cause the catalyst to be adsorbed on the surface of the resin product, the catalyst solution may be brought into contact with the surface of the resin product. The conditions such as the contact time and temperature may be the same as those in the conventional case. Further, the conditions for the electroless plating treatment, the metal species to be deposited, and the like are not limited, and can be performed in the same manner as in the conventional electroless plating treatment.

  On the electroless plating layer formed according to the inventions of the above (1) and (2), when electroless plating or electroplating is further performed by a regular method, a plating layer with more excellent durability can be obtained. It is preferable to further perform electroless plating or electroplating on the electroless plating layer. Here, examples of the electroless plating metal include metals selected from the group consisting of nickel, copper, gold, silver, and metal compounds thereof, preferably nickel or copper. . Examples of the electroplated metal include copper, nickel, chromium, tin-nickel, and gold.

  The plated resin product obtained as described above is used as a printed wiring board or the like when it is plated on a plate-like product, and as a conductive fine particle when it is plated on a fine-grained product in a vehicle. The material dispersed in is used as a conductive adhesive or paint. Moreover, when using as a printed wiring board, it is good also as a multilayer structure which laminated | stacked the plating layer and the insulating layer on the product alternately. In addition, the plated resin product has a metallic luster, and the plating film adheres firmly to the surface of the material, and there is little variation in adhesion. For example, parts and decorations such as vehicles, information equipment, office equipment, etc. Can also be used.

  Hereinafter, the present invention will be specifically described based on examples. However, the present invention is not limited to these examples.

(1) Ultraviolet pretreatment An ultraviolet pretreatment was performed by irradiating a resin substrate (20 × 50 mm) made of ABS resin at 60 ° C. in the atmosphere with a synthetic quartz lamp as a light source for 1 minute with ultraviolet light having a wavelength of 254 nm. It was.
(2) Surface modification treatment Next, anatase-type titanium dioxide having an average particle size of 0.5 μm, which is a semiconductor powder, is added to water to 0.01 g / L, and stirred with a magnetic stirrer to uniformly disperse. To obtain a suspension. The ABS resin substrate subjected to the ultraviolet treatment was immersed in the liquid, and ultraviolet light having a wavelength of 380 nm or less was irradiated for 5 minutes in the liquid using a mercury lamp as a light source, thereby modifying the surface of the ABS resin substrate.
(3) Electroless NiP plating and copper plating The modified ABS resin substrate obtained as described above is immersed in a commercially available electroless NiP plating solution and then a commercially available copper sulfate plating solution, and electroless to a thickness of about 20 μm. Plated.
Despite the pretreatment time being about half of the conventional time, the adhesion between the obtained plating layer and the substrate surface was 1.0 kgf / cm or more, and the variation was small. For the adhesion, after the plating, a notch reaching the substrate from the plating layer was made with a width of 1 cm, and the adhesion strength of the plating film was measured with a tensile tester.

(Comparative Example 1)
An electroless plating resin was produced in the same manner as in Example 1 except that no ultraviolet pretreatment was performed. The adhesion between the obtained plating layer and the substrate surface was lower than 1.0 kgf / cm, and the variation was large.

(1) Ultraviolet pretreatment An ultraviolet pretreatment was performed on a resin substrate (20 × 50 mm) made of ABS resin at 50 ° C. in the atmosphere using a normal quartz lamp as the light source and irradiating with ultraviolet light having a wavelength of 254 nm for 1 minute. It was.
(2) Surface modification treatment The resin product pre-treated with ultraviolet rays as described above is immersed in pure water filled in a transparent quartz container, and resin is applied from the outside of the container using a 1 kW high-pressure mercury lamp. The substrate was irradiated with ultraviolet rays for 5 minutes.
Next, a mixed aqueous solution in which 50 g / L of NaOH and 1 g / L of sodium lauryl sulfate are dissolved is heated to 60 ° C., and each resin plate after UV treatment is immersed therein for 2 minutes to anionic surfactant (lauryl sulfate). Sodium) was adsorbed. Each resin plate adsorbed with the surfactant is pulled up, washed with water and dried, and then dissolved in 0.1% by weight of palladium chloride in 3N aqueous hydrochloric acid solution and 5% by weight of tin chloride dissolved in the catalyst solution heated to 50 ° C. Immersion for 3 minutes and then immersion in 1N aqueous hydrochloric acid for 3 minutes to activate palladium. As a result, a resin plate for plating on which the catalyst was adsorbed was obtained.

(3) Then, each resin plate for plating was immersed in a chemical nickel plating bath kept at 40 ° C. to deposit a nickel plating film for 10 minutes. The deposited nickel plating film had a thickness of 0.5 μm. Subsequently, 40 μm of copper plating was deposited on the surface of the nickel plating film in a copper sulfate-based Cu electroplating bath.
Despite the pretreatment time being about half of the conventional time, the adhesion between the obtained plated layer and the substrate surface was 1.0 kgf / cm or more, and the variation was small.

(Comparative Example 2)
A nickel plating film was deposited in the same manner as in Example 2 except that no ultraviolet pretreatment was performed. Subsequently, copper plating was deposited in a copper sulfate-based Cu electroplating bath.
The adhesion between the obtained plating layer and the substrate surface was lower than 1.0 kgf / cm, and the variation was large.

Claims (2)

  After treating resin products by irradiating them with ultraviolet rays in the atmosphere, polar groups are formed on the surface of the resin products by immersing them in a suspension of semiconductor powder and irradiating light in the solution. And electroless plating of the surface on which the polar group is formed.   Electroless plating of a resin product characterized in that the resin product is treated by irradiating the resin product with ultraviolet rays in the atmosphere, and then treated by irradiating with ultraviolet rays through water or an aqueous solution, followed by electroless plating. Method.