KR101332301B1 - Plating method using the ni-free three element alloys plating and tri-valent chromium plating - Google Patents

Abstract

The present invention relates to a plating method using nickel-free ternary alloy plating and trivalent chromium plating, the pretreatment step of pretreating the conductor; A blue and white copper strike step of copper strikes the pretreated target object with a blue and white copper strike solution; A blue and silver copper plating step of copper-plating the blue and blue copper-stripped conductor with a blue and blue copper plating solution; A copper lactic acid plating step of copper-plating the cyanide copper plated object with a lactic acid copper plating solution; A ternary alloy plating step of plating a nickel-free ternary alloy on the lactic acid copper plated conductor by using a ternary alloy plating solution including a copper precursor, a tin precursor, and a zinc precursor; And a trivalent chromium plating step of plating trivalent chromium on the three-alloy plated member by using a trivalent chromium plating solution including a trivalent chromium precursor. According to the present invention, the surface properties such as corrosion resistance, acid resistance, and wear resistance and adhesion between the plating layers are excellent while overcoming environmental regulation and nickel regulation, thereby obtaining a highly reliable metal plating surface.

Description

Plating method using nickel-free ternary alloy plating and trivalent chromium plating {PLATING METHOD USING THE NI-FREE THREE ELEMENT ALLOYS PLATING AND TRI-VALENT CHROMIUM PLATING}

The present invention relates to a plating method using nickel-free ternary alloy plating and trivalent chromium plating, and more particularly, does not contain harmful substances such as hexavalent chromium (Cr) and nickel-free (Ni-free). Nickel-free ternary alloy plating, which does not induce nickel allergy (Ni-Allergy) and is free to European nickel regulation, and at the same time, it has excellent corrosion resistance, acid resistance, and abrasion resistance. It relates to a plating method using trivalent chromium plating.

Conductors such as metals and nonconductors such as synthetic resins and ceramics are widely used in general home appliances and various industrial fields. In general, the surface of such a material is provided with a plan to impart smoothness, glossiness, decorative texture, and the like, thereby improving the dignity. Plating technology is a highly precise surface treatment technology that increases the value of metal materials, such as improving the corrosion resistance, abrasion resistance, heat resistance and the like of the above-described materials, in particular, such as metal, and improve the color and gloss of the metal surface. Among various platings, plating using chromium (Cr) is very advantageous in corrosion resistance and abrasion resistance (hardness).

In general, surface treatment techniques based on chromium are largely classified into electrolytic chromium plating using electric energy and chromate treatment by chemical conversion treatment. However, surface treatment technology using chromium, such as electrolytic chromium plating and chromate treatment, can be used as an effective surface treatment process because hexavalent chromium, a toxic toxic substance, which is being used around the world, is used as a basic substance. I'm facing a situation where I can't. Accordingly, although attempts have been made to study and commercialize non-chromium-based surface treatment technologies such as Sn / Co, Sn / Ni, Ni / W, and Co / W. No innovative materials and processes have been proposed to replace features such as mass production, price, ease of operation and bath care.

Among these, in order to develop a surface treatment technology for replacing hexavalent chromium, an efficient and environmentally friendly plating process has begun to be applied. For example, the automotive industry is applying trivalent chromium plating to comply with the EU's end-of-life vehicle (ELV) disposal guidelines. Some apply. For example, Korean Patent No. 10-0977068 discloses a plating apparatus and a trivalent chromium alloy plating solution for forming an amorphous trivalent chromium alloy plating layer.

However, the trivalent chromium plated coating is significantly lower in corrosion resistance compared to the hexavalent chromium plated coating, and its utilization is low. Accordingly, some techniques for forming trivalent chromium plating on nickel plating films excellent in corrosion resistance and abrasion resistance have been applied.

However, as recent reports of damages to Ni-Allergy have been reported in many parts of the world, including Europe, the demand for nickel-free on metal surface-treated components is gradually increasing. The use of nickel is regulated. Accordingly, in the case of accessories, another plating for nickel-free (Ni-free) is applied.

In addition, in the case of mobile phone-related parts, three-way alloy plating technology has been developed in consideration of nickel-free, ease of wastewater treatment, and economical efficiency. Ternary alloys are generally composed of copper (Cu), tin (Sn), and zinc (Zn), which have excellent corrosion resistance under any conditions, low electrical resistance like silver (Ag), and nickel (Ni) and It has a high hardness and wear resistance.

In addition, a technique has been attempted to plate trivalent chromium as the outermost layer on the ternary alloy plating layer as described above. For example, in Korean Patent Laid-Open Publication No. 10-2008-0103238, copper is first plated on a conductor, and then a three-way alloy such as Cu-Sn-Zn is plated thereon, and a platinum (on the three-way alloy plating layer is formed). After forming precious metal plating layers, such as Pt) and silver (Ag), the method of plating trivalent chromium in outermost is proposed.

However, the conventional plating method can solve the problem of nickel allergy by not using nickel, and it is environmentally friendly because it does not use hexavalent chromium or lead (Pb), which are harmful substances for environmental regulation, but it is corrosion-resistant, acid-resistant, Surface properties such as wear resistance and the like, the adhesion between the conductor and the plating layer is low, there is a problem that does not sufficiently satisfy the reliability. Accordingly, there is a demand for a plating technology that can solve the nickel allergy problem and overcome barriers to environmental regulation while obtaining high reliability.

Republic of Korea Patent No. 10-0977068 Republic of Korea Patent Publication No. 10-2008-0103238

Therefore, the present invention does not contain harmful substances such as hexavalent chromium (Cr) and overcomes barriers of environmental regulation, as well as nickel-free (Ni-free) while overcoming nickel allergy (Ni-Allergy), At the same time, the object of the present invention is to provide a plating method using nickel-free three-way alloy plating and trivalent chromium plating, which has excellent surface properties and adhesion such as corrosion resistance, acid resistance, and abrasion resistance to obtain a highly reliable metal plating surface. have.

The present invention to achieve the above object,

A pretreatment step of pretreating the subject;

A blue and white copper strike step of copper strikes the pretreated target object with a blue and white copper strike solution;

A blue and silver copper plating step of copper-plating the blue and blue copper-stripped conductor with a blue and blue copper plating solution;

A copper lactic acid plating step of copper-plating the cyanide copper plated object with a lactic acid copper plating solution;

A ternary alloy plating step of plating a nickel-free ternary alloy on the lactic acid copper plated conductor by using a ternary alloy plating solution including a copper precursor, a tin precursor, and a zinc precursor; And

The present invention provides a plating method including a trivalent chromium plating step of plating trivalent chromium on a three-alloy plated member using a trivalent chromium plating solution including a trivalent chromium precursor.

At this time, the cyanide copper strike liquid, copper cyanide 40 ~ 50g / L, sodium cyanide 40 ~ 60g / L, Rotsel salt 5 ~ 15g / L and sodium carbonate 2 ~ 8g / L based on 1 liter (L) of strike liquid and,

The cyanide copper plating solution contains copper cyanide 110 ~ 130g / L, sodium cyanide 130 ~ 150g / L, potassium hydroxide 25 ~ 45g / L on the basis of 1 liter (L) of the plating solution,

The copper lactate plating solution preferably contains 60 to 100 g / L copper sulfate, 170 to 210 g / L sulfuric acid, and 40 to 80 mg / L chlorine ion based on 1 liter (L) of the plating solution.

In addition, the three-way alloy plating solution is based on 1 liter (L) of the plating solution, copper cyanide 12 ~ 15g / L, sodium carbonate 65 ~ 80g / L, zinc oxide 1.2 ~ 1.4g / L, sodium cyanide 45 ~ 55g / L and hydroxide It is good to include 12 to 20 g / L of potassium.

And the trivalent chromium plating solution, chromium chloride 150 ~ 200g / L, potassium formate 2 ~ 5g / L, ammonium bromide 5 ~ 10g / L, ammonium chloride 5 ~ 10g / L, potassium chloride 20 based on 1 liter (L) plating solution It is preferred to include ˜30 g / L and boric acid 100 to 150 g / L.

In addition, according to a preferred embodiment, in the three-way alloy plating step, the temperature of the three-way alloy plating solution is maintained at 50 to 60 ℃, electrolytic plating for 10 to 40 minutes (min) at a current density of 0.1 to 0.5 A / dm ² It is good.

In addition, in the trivalent chromium plating step, it is preferable to maintain the temperature of the trivalent chromium plating solution at 30 to 35 ° C., and to perform electroplating for 1 to 5 minutes (min) at a current density of 9 to 12 A / dm ² .

According to the present invention, it is possible to obtain a plating layer that does not contain harmful substances such as hexavalent chromium (Cr) and overcomes the barriers of environmental regulation and does not cause nickel allergy as Ni-free. have. It is also free from European nickel regulations, which regulate the use of nickel.

In addition, while overcoming environmental regulations and nickel regulation as described above, at the same time excellent surface properties such as corrosion resistance, acid resistance, abrasion resistance and adhesion between the plating layer has the effect of obtaining a highly reliable metal plating surface.

Hereinafter, the present invention will be described in detail.

The plating method according to the present invention is a pretreatment step of pretreatment of the subject, a cyanide copper strike step of copper strike the pretreated target object with a cyanide copper strike liquid, a cyanide copper plating the cyanide copper strike the conductor with a cyanide copper plating solution Copper plating step, copper oxide plating step of copper plating the cyanide copper plated conductor with a lactating copper plating solution, ternary alloy plating step of plating a nickel-free three-way alloy on the copper-clad plated conductor, and the three-way alloy plated The trivalent chromium plating step of plating the trivalent chromium. In the present invention, "cheonghwadong" means "cyanide copper", that is, copper cyanide, "lactic acid copper" means "copper sulfate," that is, copper sulfate. Each step will be described as follows.

(1) pretreatment step

First, the subject is pretreated.

In the present invention, the object to be subjected to the surface treatment, that is, the plating, which includes a metal, a synthetic resin, a ceramic, and the like, and may be preferably selected from metal materials. In addition, the metal (base metal) as the conductor includes a single metal or an alloy, for example, a single metal such as magnesium (Mg), aluminum (Al), iron (Fe), and copper (Cu) or one selected from these It may be an alloy containing the above metals. In addition, in the present invention, the conductor includes a material such as a plate, a rod, or the like, as well as a semifinished product, a finished product, and a part for manufacturing these semi / finished products.

The pretreatment is not particularly limited. The pretreatment may be carried out by a method conventionally performed in the art, and the pretreatment may include, for example, a washing process for removing foreign substances.

The pretreatment preferably includes a degreasing step of treating the subject with a degreasing solution. In this case, the degreasing step may include at least one selected from an immersion degreasing step of depositing and degreasing the subject in a degreasing solution, and an electrolytic degreasing step of electrolytic degreasing of the subject in a degreasing solution. Such deposition and electrolytic degreasing can effectively remove not only impurities but also oil components.

The degreasing liquid is not particularly limited, but may include at least one selected from sodium hydroxide (NaOH) and a surfactant. At this time, the degreasing liquid, sodium hydroxide (NaOH) is preferably contained in a concentration (content) of 100g / L or more based on 1 liter (L) of the degreasing liquid. For example, it is preferable to include 100 ~ 150g / L sodium hydroxide (NaOH). As such, when sodium hydroxide (NaOH) is included in the degreasing solution, the oil component of the subject can be effectively removed.

In addition, it is preferable that the said degreasing liquid contains 2-7 ml / L of surfactants with respect to 1 liter (L) of whole degreasing liquids. In this case, the surfactant may be preferably ethoxylated nonlyphenol. As such, when the degreasing solution contains a surfactant, not only the oil component of the subject but also a release agent material (Si component) can be effectively removed. According to a specific embodiment, the degreasing liquid is sodium hydroxide (NaOH) 100 to 150 g / L, sodium carbonate (Na ₂ CO ₃ ) 80 to 150 g / L and surfactant 2 to 7 ml based on 1 liter (L) of degreasing solution. It may be composed of an aqueous solution containing / L.

The degreasing step, that is, the deposition degreasing step and the electrolytic degreasing step is not particularly limited. For example, the immersion degreasing process may be performed by depositing a subject in the degreasing solution as described above, and then maintaining the same at a temperature of 50 to 80 ° C. for 5 to 30 minutes. In addition, the electrolytic degreasing process may be performed by depositing a subject in the degreasing solution as described above, and then applying a voltage of 2-5V for 5-30 minutes at a temperature of 50-80 ° C.

By the above pretreatment, that is, the washing and / or degreasing process, foreign substances as well as oil components can be effectively removed, which can increase the copper strike efficiency in the subsequent cyanide copper strike step.

(2) Cheonghwa-dong  Strike stage

After the pretreatment (washing and / or degreasing) as described above, the pretreatment is subjected to a cyanide copper strike. The cyanide copper strike proceeds to improve the adhesion between the conductor (material layer) and the plating layer. Specifically, by the blue and white copper strike treatment, a thin copper (Cu) film is formed on the surface of the object to increase the adhesion between the object and the copper plating layer. In addition, the blue and white copper plating efficiency may be increased by the blue and blue copper strike treatment.

The said blue and white copper strike is advanced by the method of immersing a to-be-contained body in a blue and blue copper strike liquid. According to a preferred embodiment, the sintered copper strike is, by immersing the subject in the sintered copper strike liquid, and then proceeds to apply a voltage of 2.5 to 4.5V at a constant voltage for 1 to 5 minutes at a temperature of 30 ~ 60 ℃ It is good to be.

The cyanide copper strike liquid may be a solution containing at least copper cyanide (CuCN), preferably, a solution containing copper cyanide and sodium cyanide. The cyanide copper strike liquid is 40 to 50 g / L copper cyanide, 40 to 60 g / L sodium cyanide, 5 to 15 g / L Rochelle salt, and 2 to 8 g sodium cyanide, based on 1 liter (L) of the cyanide copper strike liquid. It is more preferable to use a solution containing / L. At this time, the Rossel salt is to flow the electricity well so that the plating is good even at low current, which may be used, for example, at least one selected from potassium sodium tartaric acid and sodium potassium salt tin.

(3) Cheonghwa-dong  Plating step

After the sintered copper strike as described above, the sintered copper strikes the copper-plated copper (Cu) to the copper plating solution. In the present invention, the cyanide copper plating means to form a copper (Cu) plating layer using a plating solution containing cyanide copper (copper cyanide).

The cyanide copper plating is performed by electrolytic plating using a cyanide copper plating solution. According to a preferred embodiment, the cyanide copper plating is carried out by a method of electrolytic plating with a constant current for 1 to 40 minutes (min) at a current density of 1 to 4A / dm ² while maintaining the temperature of the cyanide copper plating solution at 50 ~ 65 ℃ It is good to be.

In addition, in performing the cyanide copper plating, pure copper is used as the positive electrode, and the cyanide copper strike conductor is connected to the negative electrode to stir the negative electrode.

The cyanide copper plating solution may be a solution containing at least copper cyanide. Preferably, copper cyanide 110 to 130 g / L, sodium cyanide 130 to 150 g / L and potassium hydroxide 25 to 45 g based on 1 liter (L) of the total cyanide copper plating solution. It is advisable to use a solution containing 10-30 g / L of L / lot and salt. At this time, as the above-mentioned loxel salt, for example, one or more selected from potassium sodium tartaric acid, sodium tin potassium, and the like may be used.

In addition, the cyanide copper plating solution may further include an additive in addition to the above components. The additive may be used as a main component of the cyanide copper polish, containing a small amount of a surfactant, such an additive may be included in 1 ~ 3ml / L on the basis of 1 liter (L) of the cyanide copper plating solution.

(4) Lactic acid copper plating step

After the cyanide copper plating is performed as described above, the cyanated copper plated member is plated with a copper lactate plating solution (Cu). Copper lactate plating in the present invention means to form a copper (Cu) plating layer using a plating solution containing copper lactate (copper sulfate, that is, copper sulfate).

The copper lactate plating is performed by electrolytic plating using a copper lactate plating solution. According to a preferred embodiment, the copper lactate plating is carried out by the method of electrolytic plating with a constant current for 1 to 40 minutes (min) at a current density of 1 to 5A / dm ² while maintaining the temperature of the copper lactate plating solution at 20 ~ 30 ℃ good.

In addition, in carrying out the copper lactic acid plating, it is preferable to use a phosphorus-containing copper as an anode and to connect the blue-plated copper-plated conductor to a cathode, and to carry out a weak air agitation and liquid agitation together with the agitation of the cathode.

The copper lactate plating solution may be a solution containing at least copper sulfate, preferably containing copper sulfate 60 ~ 100g / L, sulfuric acid 170 ~ 210g / L and chlorine ion 40 ~ 80mg / L based on 1 liter (L) of the total copper lactate plating solution It is better to use a solution.

In addition, the copper lactate plating solution may further include an additive in addition to the above components. The additive has a copper lactate polish as a main component, it may be used to contain a small amount of surfactant, such additives may be included in 2 ~ 6ml / L based on 1 liter (L) of the total copper lactate plating solution.

As described above, in plating copper (Cu) in the present invention, it proceeds through the cyanide copper strike, cyanide copper plating and lactic acid copper plating process, wherein the adhesion is deposited as described above by the cyanide copper strike process. A sufficient thickness of the copper plating layer is secured by the cyanide copper plating process, and the gloss of copper is secured by the lactic acid copper plating process. In this case, when the lactic acid copper plating is performed immediately after the copper strike without performing the cyanide copper plating, pits may occur on the plating surface when the lactic acid copper plating is performed for a long time to secure the thickness.

Accordingly, in order to prevent pit generation and to secure sufficient thickness and gloss of the copper plating layer in plating copper (Cu), according to the present invention, the blue and blue copper strike and the blue and blue copper Plating and lactic acid copper plating process proceeds sequentially.

On the other hand, according to an exemplary embodiment of the present invention, it is preferable to further perform an activation process between the blue and blue copper plating process. Specifically, after performing the cyanide copper plating, it is good to activate the cyanide copper plated conductor prior to proceeding the lactic copper plating. By this activation treatment, copper (Cu) plating efficiency can be increased during copper lactate plating. The activation process may be performed by immersing the copper plated copper plated object in the activation solution, and then activating the surface of the object by, for example, holding it at room temperature (about 5 to 35 ° C.) for 10 seconds to 5 minutes. have. In addition, 2-10 weight% of sulfuric acid and aqueous solution can be used for the said activation process liquid, for example.

(5) Three-way alloy plating step

After carrying out the copper phosphate plating as described above, the ternary copper plated member is plated with a ternary alloy plating solution. Specifically, a nickel-free ternary alloy composed of copper (Cu), tin (Sn), and zinc (Zn) is plated.

The three-way alloy plating proceeds by electroplating using a nickel-free three-way alloy plating solution. According to a preferred embodiment, the three-way alloy plating is a method of maintaining the temperature of the three-way alloy plating solution at 50 to 60 ℃, electrolytic plating with a constant current for 10 to 40 minutes (min) at a current density of 0.1 to 0.5 A / dm ² Good to go.

In addition, in carrying out the three-way alloy plating, it is preferable to use a graphite plate as an anode, connect the lactic acid copper plated conductor to a cathode, and stir the liquid. Under these conditions, a Cu-Sn-Zn ternary alloy plating layer of at least 5 µm can be obtained.

The three-way alloy plating solution may be a plating solution containing at least a copper precursor, a tin precursor and a zinc precursor without containing nickel, and preferably 12 to 15 g / L copper cyanide based on 1 liter (L) of the three-way alloy plating solution. It is preferable to use a plating solution containing sodium 65 to 80 g / L, zinc oxide 1.2 to 1.4 g / L, sodium cyanide 45 to 55 g / L and potassium hydroxide 12 to 20 g / L.

In addition, the three-way alloy plating solution may further include an additive in addition to the above components. As the additive, one or more selected from a brightener for glossing of the three-way alloy and an electrodeposition agent for uniform electrodeposition of the three-way alloy may be used, and such additives are based on 1 liter (L) of the three-way alloy plating solution. In the case of 8 ~ 12ml / L, may be included as 8 ~ 12ml / L in the electrodeposition agent.

In addition, it is preferable to form a ternary alloy plating layer including Cu 50 to 60% by weight, Sn 25 to 35% by weight, and Zn 15 to 20% by weight through the ternary alloy plating process as described above. In addition, the ternary alloy plating layer formed by the above process ensures corrosion resistance and plating thickness and is excellent in adhesion to the trivalent chromium plating layer, and excellent in corrosion resistance, low electrical resistance like silver (Ag), and like nickel (Ni). It has a high hardness and excellent plating resistance.

(6) trivalent chromium plating step

After the ternary alloy plating is performed as described above, the trivalent chromium is plated with a trivalent chromium plating solution on the to-be-plated member.

The trivalent chromium plating is performed by electrolytic plating using a trivalent chromium plating solution. According to a preferred embodiment, the trivalent chromium plating is a method of maintaining the temperature of the trivalent chromium plating solution at 30 ~ 35 ℃, electroplating with a constant current for 1 to 5 minutes (min) at a current density of 9 ~ 12A / dm ² It is good to proceed to.

In addition, in performing the trivalent chromium plating, it is preferable to use a graphite plate as an anode, connect the three-alloy plated conductor to the cathode, and perform air agitation. When plating under such conditions, a trivalent chromium plating layer of at least 0.3 μm or more can be obtained.

The trivalent chromium plating solution may be any plating solution containing at least a trivalent chromium precursor. At this time, the trivalent chromium precursor may be used at least one selected from chromium chloride, chromium sulfate, chromic anhydride and the like. In addition, a trivalent chromium plating liquid can use a sulfuric acid bath or a chloride bath.

Specifically, the trivalent chromium plating solution may be a sulfuric acid bath including 240 to 260 g / L of chromic anhydride and 1.2 to 2.6 g / L of sulfuric acid based on 1 liter (L) of the total trivalent chromium plating solution. The trivalent chromium plating solution is preferably 150 to 200 g / L chromium chloride, 2 to 5 g / L potassium formate, 5 to 10 g / L ammonium bromide, and 5 to 10 g ammonium chloride, based on 1 liter (L) of the total trivalent chromium plating solution. It is preferable to use a chloride bath containing / L, potassium chloride 20-30 g / L and boric acid 100-150 g / L.

In addition, the trivalent chromium plating solution may further include an additive in addition to the above components. As the additive, one or more selected from a brightener for gloss of the trivalent chromium plating layer and an electrodeposition agent for uniform electrodeposition of the trivalent chromium plating layer may be used, and such an additive may be used based on 1 liter (L) of the trivalent chromium plating solution. For example, the gloss agent may include 2 to 20ml / L, and the electrodeposition agent may include 2 to 20ml / L, but is not limited thereto.

By the above trivalent chromium plating process, excellent gloss, corrosion resistance and hardness can be ensured. Specifically, trivalent plating is less excellent in corrosion resistance than hexavalent chromium plating and difficult to secure plating thickness. That is, the trivalent chromium plating formed by a general conventional process is difficult to thicken the plating layer without the plating gloss and corrosion resistance of hexavalent chromium as a whole. However, hexavalent chromium plating is a barrier to environmental regulation due to its harmfulness as described above.

According to the present invention, the trivalent chromium plating process as described above, that is, the trivalent chromium plating formed by the process conditions of the electrolytic plating and the composition of the plating solution exhibits the physical properties of hexavalent chromium. Specifically, a trivalent chromium plating layer having excellent gloss, corrosion resistance and hardness is coated. For example, a plating layer having excellent hardness of Hv 900 to 950 can be obtained.

In addition, in performing trivalent chromium plating on the above process conditions, it is preferable to make thickness of a trivalent chromium plating layer into 0.3 micrometer-0.5 micrometer. The trivalent chromium plating layer of such thickness ensures abrasion resistance and the like with excellent corrosion resistance and hardness. At this time, if the thickness of the plating layer is less than 0.3㎛, corrosion resistance and hardness may be insignificant, and if it is too thick exceeding 0.5㎛ may cause pin holes or cracks in the plating surface.

On the other hand, according to an exemplary embodiment of the present invention, it is preferable to further perform an activation treatment between the three-way alloy plating and the trivalent chromium plating process. Specifically, after the three-way alloy plating is performed, it is preferable to activate the three-alloy plated conductor prior to proceeding trivalent chromium plating. By this activation treatment, the plating efficiency in the trivalent chromium plating can be increased. The activation treatment may be performed by immersing a three-alloy plated member in the activation treatment liquid, and then activating the surface of the subject by, for example, holding it at room temperature (about 5 to 35 ° C) for 10 seconds to 5 minutes. Can be. In addition, 10 to 50 weight% aqueous hydrochloric acid solution can be used for the said activation process liquid, for example.

According to the present invention described above, it is possible to obtain a plating layer that does not cause nickel allergy (Ni-Allergy) by using an environmentally friendly nickel-free (Ni-free) three-way alloy plating process, the European market that regulates the use of nickel It is also possible to advance to. In the case where the ternary alloy is plated under the above conditions, the corrosion resistance and the thickness can be secured as described above. In addition, when the trivalent chromium is plated under the above conditions, it is possible to secure excellent corrosion resistance, hardness and wear resistance without using hexavalent chromium which is a hazardous substance. And adhesiveness between each plating layer is excellent.

Therefore, according to the present invention, while overcoming environmental regulations and nickel regulation, at the same time excellent in the surface properties such as corrosion resistance, acid resistance, abrasion resistance and adhesion between the plating layers, it is possible to obtain a highly reliable metal plating surface.

Hereinafter, embodiments of the present invention will be exemplified. The following examples are provided to aid understanding of the present invention, and thus the technical scope of the present invention is not limited thereto.

[Example]

< Subject  Pretreatment>

It is a photograph of a magnesium alloy (hereinafter referred to as a 'test specimen') as a subject (metal). First, the degreasing solution was bathed in order to pretreat the specimen. The degreasing liquid uses an aqueous solution containing 100 g / L of sodium hydroxide, 100 g / L of sodium carbonate, and 5 ml / L of ethoxylated nonlyphenol as the surfactant component, based on 1 liter (L) of degreasing solution. It was.

After the specimen was immersed in the bath degreased liquid, it was maintained for 15 minutes at a temperature of 70 ℃ to perform the degreasing. Thereafter, after washing the specimen subjected to the immersion degreasing, electrolytic degreasing was performed using the same degreasing solution. Electrolytic degreasing was performed by immersing the specimen in an electrolytic degreasing bath containing degreasing liquid, and then applying a voltage of 3 V for 10 minutes at a temperature of 70 ° C.

< Cheonghwa-dong  Strike>

Copper strike treatment was performed on the specimens pretreated (immersion degreasing and electrolytic degreasing) as described above. Specifically, the pretreated specimen was immersed in the cyanide copper strike solution, and then a voltage of 4V was applied at a constant voltage for 2 min while maintaining the temperature of the strike solution at 45 ° C.

At this time, the cyanide copper strike liquid, 45 g / L copper cyanide, 50 g / L sodium cyanide, 10 g / L of sodium salt (potassium sodium tartaric acid) and 5 g / L of sodium cyanide based on a total of 1 liter (L) of strike liquid An aqueous solution was used.

< Cheonghwa-dong  Plating>

The blue and blue copper plated specimens were subjected to blue and blue copper plating. Specifically, pure copper is used as an anode, and the clarified copper stripe-treated specimen is connected to the cathode, and the electrolytic plating is carried out at a constant current for 20 min at a current density of 1 A / dm ² while stirring the cathode to produce copper on the surface of the specimen. (Cu) was plated. At this time, the temperature of the cyanide copper plating solution was maintained at 60 ℃.

The cyanide copper plating solution is 120 g / L copper cyanide, 140 g / L sodium cyanide, 30 g / L potassium hydroxide, 20 g / L loxel salt (potassium sodium tartaric acid) and additive A 2 ml / L An aqueous solution containing was used. The additive A was used as a main component of the cyanide copper polish agent, but containing a small amount of a surfactant (trade name CYCO # 35).

<Lactic acid copper plating>

The copper-clad copper plated specimens were subjected to lactic acid copper plating. At this time, prior to the lactic acid copper plating, the specimen was activated first. 5 wt% sulfuric acid and aqueous solution was used as the treatment solution for the activation treatment. The activation treatment was carried out by immersing the cyanated copper plated specimens in the sulfuric acid and aqueous solution for 1 minute at room temperature (about 20 ℃).

Next, the phosphorus copper is used as the anode, and the activated specimen is connected to the cathode, followed by electroplating with a constant current for 30 min at a current density of 2 A / dm ² while stirring and air stirring together with the cathode stirring. Cu) was plated. At this time, the temperature of the lactic acid copper plating solution was maintained at 25 ° C.

The aqueous copper lactate plating solution was used as an aqueous solution containing 80 g / L copper sulfate, 190 g / L sulfuric acid, 60 mg / L chlorine ion, and 4 mL / L of additive B based on 1 liter (L) of the total plating solution. The additive B used a lactic acid copper polish as a main component, but containing a small amount of surfactant (trade name CUBRAC 440 BASE).

<Three-Way Alloy Plating>

A tri-alloy of Cu—Sn—Zn was plated on the lactic acid copper plated specimen.

Specifically, using a graphite plate as an anode, connecting the lactic acid copper plated specimen to the cathode, and performing electrolytic plating at a constant current for 40 min at a current density of 0.2 A / dm ² while stirring the liquid, based on the weight of the three-way alloy plating layer. A ternary alloy of Cu—Sn—Zn consisting of 55 wt% Cu, 29 wt% Sn, and 16 wt% Zn was plated. At this time, the temperature of the three-way alloy plating solution was maintained at 55 ℃.

And the three-way alloy plating solution, 13 g / L copper cyanide, 70 g / L sodium oxide, 1.3 g / L zinc oxide, 50 g / L sodium cyanide, 18 g / L potassium hydroxide, additive C 10 ml on the basis of 1 liter (L) of the plating solution An aqueous solution containing / L and additive D 10 ml / L was used. The additive C is used for gloss, and contains a tellurium (Te) as a main component (brand name NB 4043A), and the additive D is for uniform electrodeposition, and contains 93% by weight of calcium (Ca). (Brand name NB 4043B) was used.

<Trivalent chromium plating>

Trivalent chromium was plated on the specimen coated with the three-way alloy. At this time, prior to trivalent chromium plating, the specimen was first activated. 30 wt% aqueous hydrochloric acid solution was used as a treatment liquid for the activation treatment. The activation treatment was performed by immersing the three-alloy plated specimen in the aqueous hydrochloric acid solution at room temperature (about 20 ° C.) for 3 minutes.

Subsequently, the graphite plate was used as the anode, and the activated treated specimen was connected to the cathode, followed by electroplating with constant current for ² min at a current density of 11 A / dm ² while stirring the air to plate trivalent chromium. At this time, the temperature of the trivalent chromium plating liquid was kept at 32 degreeC. The trivalent chromium plating solution is based on a total of 1 liter (L) of chromium chloride, chromium chloride 180g / L, potassium formate 3g / L, ammonium bromide 8g / L, ammonium chloride 8g / L, potassium chloride 25 / L and boric acid 120g / L An aqueous solution containing was used.

The physical properties of the specimens plated as above were evaluated as follows.

<Test Example 1>

In order to confirm the corrosion resistance of the plated specimens, a salt spray test was performed. The salt spray test was carried out in accordance with KS D 9502: 2009 for 72 hours under conditions of 5 wt% NaCl aqueous solution, test temperature 35 ± 0.5 ° C, spray pressure 0.098 ± 0.002 MPa, spray amount 1.4ml / h at 80cm2. During the exposure to a salt spray environment. The results of the salt spray test are shown in Table 1 below. The test resulted in no corrosion after 72 hours of saline spraying.

                       <Salt Spray Test Results> Brine concentration Test temperature Spray pressure Spray volume 5wt% NaCl (35 ± 0.5) ℃ (0.098 ± 0.002) MPa 1.4ml / h at 80㎠ Test Items Criteria Test result Test Methods Salt spray
Test After 72 hours of saline spraying,
No corrosion Satisfying criteria KS D 9502: 2009

<Test Example 2>

Acid resistance was tested on the plated specimens. The acid resistance test was performed by immersing the plated specimen in pH 4.6 buffer for 72 hours to check for discoloration. Acid resistance test results are shown in the following [Table 2]. As a result, it was evaluated that acid resistance (no discoloration) was excellent even after 72 hours immersion.

                      <Acid resistance evaluation results> Test Items Test result Test Methods Acid resistance test
(72 hours) No discoloration Immerse in pH4.6 buffer for 72 hours.

<Test Example 3>

In order to confirm adhesion to the plated specimens, abrasion resistance test and thermal shock test were conducted.

The abrasion resistance test was based on KS D 8335: 2001. Specifically, the abrasion resistance test was a tapered wear method, using CC-800 abrasive paper was tested for the degree of wear without the use of lubricant at a load of 5N.

In addition, the thermal shock test was performed by repeatedly performing a total of 24 cycles with an image of 80 ° C. for 2 hours and minus 40 ° C. for 2 hours for 1 cycle.

The wear resistance and thermal shock test results are shown in the following [Table 3] and [Table 4], respectively. As a result of the test, both wear resistance and thermal shock were good, and it was found that each plating layer of copper plating, ternary alloy plating and trivalent chromium plating on the specimen had excellent adhesion.

                        <Evaluation of Wear Resistance> Test Items result Test Methods Abrasion resistance
(Taberized wear, CC-800 abrasive, 5N load) 1000 or more KS D 8335: 2001

                      <Thermal Shock Evaluation Results> Test Items Test result Test Methods After thermal shock test
Appearance clear 2 hours at 80 ° C, 2 hours at -40 ° C,
24 cycles in total

<Test Example 4>

For the plated specimens, the detection of nickel and harmful substances was evaluated as follows.

First, in order to confirm nickel free, nickel release amount was evaluated based on EN 1811: 1998 + A1: 2008 as a test standard. Nickel Spot Test was evaluated based on PD CR 12471: 2002 as a test criterion.

Identification of hazardous substances was assessed on the basis of RoHS. Pb, Cd, Hg, Cr ^{6 +} , PBBs, PBDEs were used for the evaluation of hazardous substances. The test criteria were based on IEC62321: 2008. At this time, the evaluation of Pb, Cd, Hg was used the test equipment ICP-OES, the evaluation of Cr ^{6 +} was used the test equipment UV-vis, spectrophotometer, and the evaluation of PBBs, PBDEs was used the test equipment GC / MS.

The above evaluation results are shown in the following [Table 5]. As a result of the evaluation, as shown in Table 5, the nickel release test showed excellent results of 0.1 µg / (cm 2 week) or less, and no discoloration occurred in the nickel spot test. In addition, in the detection of hazardous substances, the six major hazardous substances Pb, Cd, Hg, Cr ^{6 +} , PBBs, PBDEs were not detected or detected below the environmental regulatory allowable concentration, it was found to be environmentally friendly and harmless to the human body.

                       <Environmental hazard assessment results> Test Items
unit Test result Test Methods Nickel emission amount
㎍ / (㎠week) 0.01 or less EN 1811: 1998 + A1: 2008 Nickel Spot Test - Negative
(No discoloration) PD CR 12471: 2002 Lead (Pb)




Mg / kg 29 IEC 62321: 2008
Test Equipment: ICP-OES Cadmium (Cd) Not detected (detection limit 1) IEC 62321: 2008
Test Equipment: ICP-OES Mercury (Hg) Not detected (detection limit 1) IEC 62321: 2008
Test Equipment: ICP-OES Hexavalent chromium (Cr ^{6 +} ) Voice (<0.02) IEC 62321: 2008
UV-Vis. Spectrophotometer PBBs Not detected (detection limit 5) IEC 62321: 2008
Test equipment: GC / MS PBDEs Not detected (detection limit 5) IEC 62321: 2008
Test equipment: GC / MS

As confirmed in the above test example, it can be seen that the specimen plated according to the present invention is excellent in all the physical properties required in the plated product, specifically corrosion resistance, acid resistance, adhesion (wear resistance, thermal shock resistance). Moreover, it turns out that a favorable result is shown also in a hazard evaluation.

Claims (7)

A pretreatment step of pretreating the subject;
A blue and white copper strike step of copper strikes the pretreated target object with a blue and white copper strike solution;
A blue and silver copper plating step of copper-plating the blue and blue copper-stripped conductor with a blue and blue copper plating solution;
A copper lactic acid plating step of copper-plating the cyanide copper plated object with a lactic acid copper plating solution;
A ternary alloy plating step of plating a nickel-free ternary alloy on the lactic acid copper plated conductor by using a ternary alloy plating solution including a copper precursor, a tin precursor, and a zinc precursor; And
By using a trivalent chromium plating solution containing a trivalent chromium precursor, comprising a trivalent chromium plating step of plating trivalent chromium on the three-alloy plated subject,
The trivalent chromium plating solution is chromium chloride 150 ~ 200g / L, potassium formate 2 ~ 5g / L, ammonium bromide 5 ~ 10g / L, ammonium chloride 5 ~ 10g / L based on 1 liter (L) of the trivalent chromium plating solution Plating method comprising a potassium chloride 20 ~ 30g / L and boric acid 100 ~ 150g / L.
The method of claim 1,
The cyanide copper strike liquid, copper cyanide 40 ~ 50g / L, sodium cyanide 40 ~ 60g / L, Rochelle salt 5 ~ 15g / L and sodium carbonate 2 ~ 8g / L on the basis of 1 liter (L) Including,
The cyanide copper plating solution includes copper cyanide 110 to 130 g / L, sodium cyanide 130 to 150 g / L, potassium hydroxide 25 to 45 g / L and loxel salt 10 to 30 g / L based on 1 liter (L) of the total cyanide copper plating solution ,
The plating process for copper lactate, characterized in that it comprises 60 to 100 g / L copper sulfate, 170 to 210 g / L sulfuric acid and 40 to 80 mg / L based on 1 liter (L) of the total acid copper plating solution.
The method of claim 1,
The three-way alloy plating solution, 12 to 15 g / L copper cyanide, 65 to 80 g / L sodium carbonate, 1.2 to 1.4 g / L zinc oxide, 45 to 55 g / L sodium cyanide, and 1 liter (L) of the total three-way alloy plating solution Plating method comprising potassium hydroxide 12 ~ 20g / L.
delete 4. The method according to any one of claims 1 to 3,
In the sintered copper strike step, the subject is immersed in the sintered copper strike liquid, and then strike by applying a voltage of 2.5 to 4.5V for 1 to 5 minutes at a temperature of 30 to 60 ℃,
In the clarified copper plating step, the temperature of the clarified copper plating solution is maintained at 50 to 65 ° C., and electrolytic plating is performed at a current density of 1 to 4 A / dm ² for 1 to 40 minutes (min),
In the copper lactate plating step, the plating method, characterized in that the temperature of the copper lactate plating solution is maintained at 20 ~ 30 ℃, electrolytic plating for 1 to 40 minutes (min) at a current density of 1 to 5A / dm ² .
4. The method according to any one of claims 1 to 3,
In the three-way alloy plating step, the temperature of the three-way alloy plating solution is maintained at 50 ~ 60 ℃, the plating method, characterized in that the electrolytic plating for 10 to 40 minutes (min) at a current density of 0.1 ~ 0.5A / dm ² .
4. The method according to any one of claims 1 to 3,
In the trivalent chromium plating step, the plating method, characterized in that the temperature of the trivalent chromium plating solution is maintained at 30 ~ 35 ℃, electroplating for 1 to 5 minutes (min) at a current density of 9 ~ 12A / dm ² .