JP2002030451A - High performance chemical plating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance chemical plating method constructing a new plating process in which, as a catalyst in the chemical plating, palladium is not used at all for solving the problems in the stability of the feed and high cost of palladium. SOLUTION: This high performance chemical plating method in which chemical plating is performed to the surface of a nonconductive material in a solution containing a reducing agent without using a palladium catalyst has a vapor depositing stage in which the surface of the nonconductive material is vapor- deposited with carbon and is further vapor-deposited with zinc and a plating stage in which the nonconductive material respectively vapor-deposited with carbon and zinc in the vapor depositing stage is subjected to chemical plating, and the surface of the nonconductive material is formed with a plating film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-performance chemical plating method for forming a chemical plating film of, for example, copper or nickel on the surface of a nonconductive material.

[0002]

2. Description of the Related Art Chemical plating (also referred to as electroless plating) in which a reducing agent is contained in a plating bath can form a film on a nonconductor such as glass. It is applied to many industrial parts such as shields. The types of metals to be chemically plated include copper, nickel, gold, silver, cobalt,
It covers a wide range such as tin, palladium and other alloys. In performing chemical plating, the plating rate is a very important factor, and the rate depends on the catalytic activity of the substrate. When the substrate is a non-conductive substance such as plastic or ceramics, the catalytic activity is weak, and the treatment at a high temperature may be restricted, and palladium having a catalytic action is effectively used. Therefore, plating of plastics typified by ABS (acrylonitrile, butadiene, styrene) resin, which is a typical example of plating on non-conductive materials, is performed by using the palladium in the following manner. First, the plating step on the ABS resin includes (1) a degreasing (washing) step, (2) an etching (surface roughening) step, (3) a neutralizing step, (4) a palladium catalyst applying step, and (5) a palladium catalyst. It is composed of a pretreatment step of an activation step and (6) a chemical nickel plating (plating) step. In addition, ABS where each process was completed
The resin is washed with water at the end of each step and sent to the next step. Next, the ABS resin having been subjected to the pretreatment step is sent to an electroplating step, and an arbitrary plating film is formed on the surface of the ABS resin.

[0003]

However, when the above-mentioned palladium is used to enhance the catalytic activity on the surface of the non-conductive substance, there are the following problems. Palladium is also widely used as a catalyst for purifying automotive exhaust gas, is a rare element, and is unevenly distributed worldwide as a resource, making it extremely expensive and poor in price stability and supply stability . Against this background, as a countermeasure against the price surge of palladium that surpasses gold and platinum,
In the plating process, techniques for collecting and reusing are being studied, but they are merely auxiliary means, and there is no drastic solution considering the cost of collection. The present invention has been made in view of such circumstances, and provides a high-performance chemical plating method that constructs a new plating process that does not use palladium at all as a catalyst for chemical plating in order to solve the supply stability and high price problems of palladium. The purpose is to do.

[0004]

According to the present invention, there is provided a high-performance chemical plating method according to the present invention, in which a non-conductive material is subjected to chemical plating in a solution containing a reducing agent without using a palladium catalyst. A high-performance chemical plating method in which carbon is vapor-deposited on the surface of a non-conductive material, and further, zinc is vapor-deposited, and chemical plating is performed on the non-conductive material on which carbon and zinc are respectively deposited in the vapor deposition process. Performing a plating step of forming a plating film on the surface of the non-conductive substance. As a result, zinc deposited on the surface of the non-conductive substance dissolves in the plating bath, and it becomes possible to precipitate a metal having a catalytic action present in the plating bath. In addition, carbon can act as an electron conductor that gives electrons generated when zinc is dissolved to a metal having a catalytic action present in a plating bath.

Here, in the high-performance chemical plating method according to the present invention, the non-conductive substance is introduced into a solution containing a mixed hydroxide of copper and nickel, and the mixed hydroxide is placed on the surface of the non-conductive substance. After the colloid is adsorbed, it is preferable that carbon and further zinc are deposited in the deposition step via the mixed hydroxide colloid. As a result, a very fine mixed hydroxide colloid adheres to the surface of the non-conductive material, and furthermore, carbon and zinc are deposited on the surface of the non-conductive material through the mixed hydroxide colloid in the deposition process. It is possible to do.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described to provide an understanding of the present invention. A molded article (hereinafter, referred to as a molded article) made of ABS resin, which is an example of a non-conductive substance to which the high-performance chemical plating method according to the first and second embodiments of the present invention is applied, is, for example, an injection molding machine. It is molded using such as. In addition, a nickel plating film, which is an example of a metal that has sufficient electric conductivity during electroplating and has a catalytic action, is formed on the surface of the molded body. The formed body on which the nickel plating film is formed is sent to a subsequent electroplating process, and is subjected to plating of, for example, copper, nickel, gold, silver, cobalt, tin, palladium, and other alloys thereof. .

Next, a method for forming a plating film on the surface of the molded body made of the ABS resin will be described. The high-performance chemical plating method according to the first embodiment of the present invention is a high-performance chemical plating method that performs chemical plating on the surface of a nonconductive substance in a solution containing a reducing agent without using a palladium catalyst. is there. This high-performance chemical plating method includes a degreasing step of cleaning the surface of a non-conductive substance, and a surface layer of the non-conductive substance in order to enhance the adhesion between the surface of the non-conductive substance and the plating film that have been cleaned in the degreasing step. (A surface roughening) step of forming an uneven portion (having a size of about 1 to 3 μm and formed uniformly on all surface layers of a non-conductive substance) in the portion, Depositing carbon on the surface of the non-conductive material on which the part was formed, and further vapor-depositing zinc; and performing chemical plating on the non-conductive material on which carbon and zinc were deposited in the deposition step, respectively. A plating step of forming a plating film on the surface of the substance. The details will be described below.

First, for example, using an injection molding machine or the like,
Predetermined shape made of BS resin (for example, disk shape, rod shape,
A molded article formed into a rectangular shape in a plan view) is manufactured.
In this way, for example, fingerprints, mechanical oil, dust, etc. adhere to the surface of the molded article molded using an injection molding machine or the like. Wash using a cleaner or the like, and then wash with water (above, degreasing step). After washing in the degreasing step, to the surface layer of the molded body washed with water, in order to attach a concave and convex portion and leave a polar group, to ensure catalyst adsorption characteristics and plating adhesion,
The molded body is immersed in, for example, a mixed solution of sulfuric acid and chromic acid, and then washed with water (the above is the etching step). Therefore, this etching step is an essential step in ABS resin plating.

After the irregularities are formed in the etching step,
In order to remove the chromic acid and the like used in the etching step from the uneven portions of the molded body, the washed body is neutralized using, for example, concentrated hydrochloric acid, and then washed with water (above, the neutralization step).
It is further dried. And, on the surface of the dried molded body,
Carbon and zinc are deposited (the above is the deposition step). As a vapor deposition method, a general vacuum vapor deposition method may be used and 10 ⁻³ Torr
In a vacuum chamber of about r, carbon and zinc are evaporated,
It is deposited on the surface of the molded body. In this vapor deposition method, a two-stage vapor deposition method in which carbon is first vapor-deposited on the surface of a molded body and zinc is vapor-deposited thereon is adopted as the vapor-deposition order. This vapor deposition thickness is not particularly limited as long as the surface of the molded body is uniformly covered with carbon or zinc, but the total thickness of carbon and zinc is 0.0
1 to 2.0 μm, more preferably 0.02 to 0.2 μm.
An effective action can be expected in the range of 2 μm. Although it does not prescribe the thickness ratio of zinc and carbon, as for carbon, carbon deposited on the surface of the molded body, considering the thickness that is difficult to peel off from the surface of the molded body,
It is better not to be too thick, with the upper limit being about 0.06 μm.

[0010] The formed body subjected to the vapor deposition treatment is immersed in a chemical nickel plating (hereinafter, referred to as chemical plating) bath to be subjected to chemical plating. In the chemical plating bath, the zinc is dissolved and acts as a driving force that facilitates the deposition of nickel. Carbon effectively participates in the initial precipitation of nickel by acting as a so-called electron conductor that gives electrons generated during dissolution of zinc to nickel precipitation. Nickel deposited efficiently due to the presence of zinc and carbon exhibits a self-catalytic action of nickel itself in a subsequent chemical plating reaction, thereby enabling a continuous chemical plating reaction. The vapor deposition of carbon and zinc facilitates the precipitation of nickel in the chemical plating bath, and furthermore, the carbon acts as an electron conductor, so that a uniform plating film (also referred to as a film) is formed on the surface of the molded body. In this case, it is not necessary that carbon and zinc completely cover the surface of the uneven portion of the molded body.

By this chemical plating, 0.1 μm or more,
Desirably, when a plating film having a thickness of 0.3 μm or more is formed, the film has sufficient electric conductivity during the subsequent electroplating, so that the chemical plating is completed (the above, the plating step). As described above, the film of the product plated by the process without using any palladium catalyst has a plating adhesion strength of 1.0 to 1.6 kg / cm in a peel (peeling) strength test and is sufficiently practical. However, the average value tends to be slightly inferior to that of the conventional process using palladium as a catalyst.

The high-performance chemical plating method according to the second embodiment of the present invention is performed after the neutralization step of the high-performance chemical plating method according to the first embodiment of the present invention (that is, etching in which uneven portions are formed). (After the step), since the non-conductive substance is introduced into a solution containing a mixed hydroxide of copper and nickel, detailed description of other parts is omitted. The high-performance chemical plating method according to the second embodiment of the present invention is a method for obtaining plating adhesion equal to or higher than that of a conventional process product using palladium as a catalyst, and the molded body (non-conductive substance) is made of copper. And a mixed hydroxide of nickel and nickel, and after the colloid of the mixed hydroxide (also referred to as hydroxide colloid) is adsorbed on the surface of the molded body, the hydroxide colloid is dried. Carbon and zinc are deposited in a deposition step via an oxide colloid.

Therefore, in the second embodiment, a hydroxide colloid is adsorbed on the surface of a molded body in a solution containing a mixed hydroxide of copper and nickel, washed with water, dried, and then carbonized.
A two-stage deposition of zinc is performed, and then a chemical plating is performed in a solution containing a reducing agent, so that a high-performance plating film can be obtained without using any palladium catalyst. And
After the plating film is formed on the surface of the molded body, the molded body is sent to a subsequent electroplating step. The finished plating product has plating adhesion equal to or higher than that of a conventional process product using palladium as a catalyst. Although the reason is not necessarily clear, the hydroxide colloid is very fine, so that it enters the inside of the hole of the uneven portion formed in the etching step, and in the next deposition step, carbon, It is estimated that zinc has the effect of drawing zinc into the hole. In other words, by depositing carbon and zinc to the fine parts inside the holes, the nickel precipitation nuclei during chemical plating are dispersed very finely, and completely inside the irregularities formed in the etching process. I presume to get into it.

The catalyst of a mixed hydroxide of copper and nickel (also referred to as hydroxide colloid) is produced, for example, by the following method. An appropriate amount of copper and nickel sulfates and an organic acid are dissolved in water to form an aqueous solution. Caustic soda is gradually added to this aqueous solution, and when the pH becomes neutral, the addition of caustic soda is stopped. When the pH rises to 4.5 or more, hydroxide is precipitated because the solubility of the metal is lost, resulting in fine precipitation. The colloidal fine precipitate is the identity of the mixed hydroxide catalyst. Therefore, the pH is 6.0-9.
The pH is preferably adjusted to 0, and in order to generate a better precipitate, the pH is preferably adjusted to 7.0 to 8.0. Here, the ratio of copper and nickel used, the type and amount of organic acid, the rate of addition of caustic soda, etc. determine the size of the colloidal particles, and determine the quality of the catalytic action. Is done. Further, as described above, in the process of the second embodiment, a dry (dry) process, that is, drying is inserted in the middle of the process, compared with a conventional method using a continuous wet (wet) process,
Although giving a seemingly unfavorable impression, drying in the middle of the process makes it possible to check for defects and correct them, which is rather an advantageous process in terms of overall product yield.

[0015]

EXAMPLES The results of tests performed by applying the high-performance chemical plating method according to the first embodiment will be described. Example 1 ABS resin for plating was injection-molded to obtain a rectangular parallelepiped towel-hanging part (hereinafter referred to as a part) having an outer diameter of 50 × 40 × 25 mm. This part is treated in a pre-treatment step to perform Ni-P chemical plating (electroless Ni plating).
-P plating). First, set the parts temperature to 65
The part is immersed in an alkaline solution (NaOH: 400 g / liter) at 5 ° C. for 5 minutes to clean the surface of the part, and the part is taken out of the alkaline solution and washed with water (degreasing step).

Next, the surface-cleaned and water-washed parts are etched at a liquid temperature of 65 ° C. (CrO ₃ : 400 g / liter, Cr ₂ O ₃ : 10 g / liter, H ₂ SO ₄ : 40).
(0 g / liter) for 5 minutes to form irregularities on the surface layer of the component, and then take out the component from the etching solution and wash with water (etching step). Then, this part is immersed in a neutralizing solution (HCl: 50 ml / liter) at a liquid temperature of 5 minutes for 5 minutes to remove the etching liquid remaining on the uneven portion formed on the surface layer of the part, and washed with water. (Neutralization step), and further drying the part (drying step). in this way,
Carbon (thickness: 0.01μ)
m) and zinc (thickness: 0.10 μm) (processing pressure: 10 ⁻³ Torr), respectively (deposition step), followed by a chemical plating bath (NiS) having a solution temperature of 60 ° C. and a pH of 6.0.
_{O 4 · 6H 2 O: 25g} / l, H ₂ NCH ₂ CO
OH: 30 g / liter, NaH ₂ PO ₂ .H ₂ O: 2
(0 g / l) for 60 minutes to perform chemical plating, and then the components were washed with water (plating step).

As described above, a uniform Ni-P chemical plating film (also referred to as a Ni-P film) is formed on the entire surface of the component in six steps including the drying step (water washing is not counted as the number of steps).
Could be obtained. A component surface conductivity by Ni-P coating is applied, as a step after the chemical plating, the liquid temperature is performed to activate the surface by dipping for 2 minutes in 30% H ₂ SO ₄ at room temperature, and washed with water. The water-washed parts, the plating bath of liquid temperature _{30 ℃ (CuSO 4 · 5H 2} O: 200g /
Liter, H ₂ SO ₄ : 50 g / liter), and electrolytic copper plating with a current density of 50 mA / cm ² was performed.
A sample for a peel strength test having a plating thickness of 50 μm was obtained. Two cuts reaching the substrate (ABS resin) were made on the surface of the obtained sample so as to have a width of 10 mm, and the peel strength when the copper plating was peeled at an angle of 90 degrees was measured. An average peel strength of 1.4 kg / cm was obtained, and it was confirmed that the coating had sufficient adhesion for practical use.

(Example 2) A result of a test performed by applying the high-performance chemical plating method according to the second embodiment will be described. After the three steps of degreasing, etching and neutralization were completed under the same conditions as in Example 1, the parts were placed in a colloid solution containing a mixed hydroxide of copper and nickel at room temperature for 1 hour.
It was immersed for 0 minutes to adsorb the hydroxide colloid on the surface of the component. After washing with water and drying, a two-stage vapor deposition process of carbon and zinc was performed under the same conditions as the vapor deposition process of Example 1. After that,
The components were processed under the exact same conditions as in the chemical plating step (plating step) and subsequent steps in Example 1 to obtain samples for peel strength tests. The result of the peel strength test was 2.1 as an average peel strength.
kg / cm was obtained, and it was confirmed to have plating adhesion not inferior to conventional products. The solution containing the mixed hydroxide was prepared by the following method. First, 0.0
NiSO ₄ · 6H ₂ O of 8 mol / l, to prepare an aqueous solution containing CuSO ₄ · 5H ₂ O 0.01 mol / liter, and 0.04 mol / l tartaric acid, 5 mole while stirring the solution / Liter of NaOH solution is gradually added, and when the pH reaches 7.8, the addition of the NaOH solution is stopped. As a result, a mixed hydroxide of copper and nickel is formed in a colloidal form in the aqueous solution,
This solution was used as a processing solution.

(Comparative Example 1) Processing was performed in exactly the same steps as in Example 1, and the drying step and the vapor deposition step were omitted. After the completion of the chemical plating process, the surface of the component was observed to be Ni-P
No film formation was observed. An attempt was made to perform electrolytic copper plating following chemical plating, but there was no conductivity, and electroplating was not possible. (Comparative Example 2) The treatment was performed in exactly the same steps as in Example 1, and in the evaporation step, only carbon evaporation was performed, and zinc evaporation was omitted. When the sample surface was observed after the completion of the chemical plating step, formation of a Ni-P film was not observed.
Subsequent electrolytic copper plating was attempted, but the electrical conductivity was low and electroplating was not possible.

(Comparative Example 3) Processing was performed in exactly the same steps as in Example 1. In the vapor deposition step, only zinc vapor deposition was performed, and carbon vapor deposition was omitted. After the completion of the chemical plating process, the surface of the component was observed.
The P film was formed, and subsequent electrolytic copper plating was also possible. When the peel strength test was performed after electrolytic copper plating, the strength was only about 0.3 kg / cm, which was a quality level far from practical use. (Comparative Example 4) The treatment was performed in exactly the same steps as in Example 1, carbon was deposited in the deposition step, and then aluminum was deposited instead of zinc deposition. After the completion of the chemical plating step, the surface of the component was observed, and no formation of a Ni-P film was observed. I tried the subsequent electrolytic copper plating,
There was no conductivity and electroplating was not possible. From the above, it can be seen that the present invention provides a revolutionary process that innovates the conventional chemical plating process based on a palladium catalyst.

As described above, the present invention has been described with reference to the first and second embodiments. However, the present invention is not limited to the configuration described in the above embodiment, and claims And other embodiments and modifications that can be considered within the scope of the matters described in the range. For example,
In the above-described embodiment, the case where a nickel plating film is formed on the surface of the molded body as a metal having sufficient electric conductivity at the time of electroplating and having a catalytic action has been described. However, it is also possible to form another metal, for example, a copper plating film on the surface of the molded body as long as the metal has sufficient electric conductivity during electroplating and has a catalytic action. Further, in the above-described embodiment, in the degreasing step, the case where the surface of the molded body is cleaned using a solvent cleaning or a non-silica-based alkali cleaner or the like is described, but if the surface of the molded body can be cleaned, Other degreasing methods can be used. In the above-described embodiment, in the etching step, the surface of the molded body is provided with a concave and convex portion and a polar group is left, and in order to ensure catalyst adsorption characteristics and plating adhesion, the molded body is formed of sulfuric acid-chromic acid. The case of immersion in the mixed solution of the above was shown. However, other etching methods can be used as long as the above effects can be obtained. In the above-described embodiment, the case where the degreasing step, the etching step, and the neutralizing step are respectively performed has been described. However, each step can be omitted as necessary.

Further, in the above-described embodiment, the case where a molded body made of ABS resin is used as an example of the non-conductive substance has been described. However, if it is a non-conductive substance, for example, polyamide resin, polyacetal resin, polycarbonate resin, polyphenylene oxide resin,
Engineering plastics such as polyester resin, for example, polysulfone resin, polyether sulfone resin (PES), polyphenylene sulfide resin (PP
S), super engineering plastics such as polyimide resin (PI), polyether imide resin (PEI), liquid crystal polymer resin (LCP), polyether ether ketone resin (PEEK), and alloys obtained by mixing this engineering plastic and super engineering plastic Reinforced plastic (FRP, CFR) filled with polymer, glass fiber, carbon fiber, etc.
A molded article made of P) may be used. Further, as a molded body made of non-conductive ceramics, for example, ceramics having mechanical functions used for grinding materials such as alumina, silicon carbide, and titanium carbide, bearings, mechanical parts, and the like, and alumina, silicon oxide, and oxides, for example. Heat-resistant materials such as titanium and titanium carbide, heat-insulating materials, ceramics with thermal functions used for electronic components, and electronic components such as sensors such as alumina, zirconium oxide, barium titanate, and silicon oxide, capacitors, and varistors. It may be a molded body made of ceramics having an electrical function. In addition, when forming a plating film on the non-conductive substance described above, a degreasing step, an etching step,
It is preferable to carry out each of the neutralization steps.

[0023]

According to the high performance chemical plating method of the present invention, zinc deposited on the surface of the non-conductive material is dissolved in the plating bath and has a catalytic action present in the plating bath. Deposit the metal. In addition, carbon can act as an electron conductor that gives electrons generated when zinc is dissolved to a metal having a catalytic action present in a plating bath. Therefore, by using metal zinc or carbon as a vapor deposition material, which is a very popular and inexpensive raw material, it becomes possible to form a plating film on the surface of a non-conductive material without using a palladium catalyst. , The economy is good. Further, it is completely free from problems such as supply of palladium raw material and stability of price, and stable production with low running cost is possible with popular raw material.

In particular, in the high-performance chemical plating method according to the present invention, a very fine colloid of mixed hydroxide adheres to the surface of the non-conductive material, and carbon and zinc are mixed and hydroxylated in the vapor deposition step. It becomes possible to vapor-deposit each on the surface of the non-conductive substance through the colloid of the substance. Therefore, without using a palladium catalyst, metal zinc or carbon is used as a vapor deposition material, which is a very popular and inexpensive raw material, and further, a raw material for producing a colloid of a mixed hydroxide such as copper sulfate, nickel sulfate, and tartaric acid. By using, it is possible to form a plating film having plating adhesion that is not inferior to conventional products on the surface of a non-conductive substance, so that economy is improved. And, in the case of the conventional palladium catalyst, a case where the catalytic activity is exhibited in an acidic solution is typical, and when the non-conductive substance contains a substance which is weak to an acid, there is a case where the base corrosion is a problem. In the case of the present invention, the vapor deposition process is not corrosive, the mixed hydroxide solution is neutral, and there is no concern about substrate corrosion.

Claims (2)

[Claims] 1. A high-performance chemical plating method for performing chemical plating on a surface of a non-conductive substance in a solution containing a reducing agent without using a palladium catalyst, wherein carbon is deposited on the surface of the non-conductive substance. A deposition step of depositing and further depositing zinc, and a plating step of performing chemical plating on the non-conductive substance on which carbon and zinc are respectively deposited in the deposition step, and forming a plating film on the surface of the non-conductive substance. A high-performance chemical plating method characterized by having: 2. The high-performance chemical plating method according to claim 1, wherein the non-conductive material is put into a solution containing a mixed hydroxide of copper and nickel, and the mixed material is applied to the surface of the non-conductive material. After the hydroxide colloid is adsorbed, carbon in the vapor deposition step via the mixed hydroxide colloid,
A high-performance chemical plating method characterized by further depositing zinc.