KR20130044661A - Electroless ni-p plating solution and plating method using the same - Google Patents

Abstract

PURPOSE: An electroless nickel-phosphorus plating solution and a plating method using the same are provided to make the eco-friendly electroless nickel-phosphorus plating solution which is free from plumbum and cadmium. CONSTITUTION: An electroless nickel-phosphorus plating solution includes a stabilizer and a brightener. The stabilizer is selected from thio-compounds. The brightener is selected from sodium molibdate, saccharin, the thio-compounds, and naphthalene based compounds.

Description

ELECTROLESS NI-P PLATING SOLUTION AND PLATING METHOD USING THE SAME}

The present invention relates to an electroless Ni-P (nickel-phosphorus) plating solution and a plating method using the same, and more particularly, an environmentally friendly electroless Ni-P plating solution containing no Pb (lead) and Cd (cadmium), and a plating solution. It relates to a plating method that can reduce the plating cost by extending the use time of the.

Metal plating technology is a highly precise technology that enhances the value of metal materials, such as improving the corrosion resistance and abrasion resistance of the metal, and improve the color and gloss of the metal surface.

Among metal plating techniques, electroless Ni-P (nickel-in) plating is the most preferred. Ni-P plating and Ni-B plating are known for electroless Ni plating, but Ni-P plating is excellent in corrosion resistance, abrasion resistance and chemical resistance, and is plated to a uniform thickness on a metal surface, which is advantageous for precise plating. In addition, it is widely used because of the low cost. Republic of Korea Patent Publication No. 10-2004-0002613 [Patent Document 1] and Republic of Korea Patent Registration No. 10-1047696 [Patent Document 2] is a technology related to electroless Ni-P plating is presented.

The plating liquid used for electroless Ni-P plating generally requires a nickel precursor (nickel salt), a reducing agent for reducing the nickel precursor, but as an additive, a stabilizer to prevent spontaneous decomposition and aging of the plating liquid, and a gloss Contains a varnish for. In addition, the plating solution may further include a pH adjuster for adjusting the pH, a complexing agent for controlling the reduction rate, a binder for improving the bonding property of the subject (metal) and the Ni-P plating layer.

In performing electroless Ni-P plating, the above plating solution is used, but first, the subject (metal) is pretreated. Pretreatment generally includes a degreasing process, an etching process, a desmut process and a zincate process. At this time, the zincate is a base zinc plating process, which is composed of a zincate primary process, a peeling process, and a zincate secondary process. Korean Patent Laid-Open No. 10-2011-0069265 [Patent Document 3] discloses a technique related to pretreatment of a metal (aluminum alloy) during electroless Ni-P plating.

However, the conventional electroless Ni-P plating solution contains Pb (lead) and Cd (cadmium), which are harmful substances. Pb and Cd are mainly contained in the plating liquid by stabilizers and brighteners. That is, conventionally, Pb compounds are generally used as stabilizers, and Cd compounds are used as polishes, and Pb and Cd, which are harmful substances, are contained in the plating solution.

Recently, the RoHS standard restricts the use of Pb and Cd. RoHS is a directive that prohibits the use of six hazardous substances in electrical and electronic products. The six harmful substances include Pb and Cd. Accordingly, electroless Ni-P plating is mainly applied to plating of computer parts, such as HDD covers, and has tended to exclude Pb and Cd according to the RoHS standard. Recently, in line with the hazardous substance regulations, the use of Pb and Cd in electroless Ni-P plating solutions has been reduced. However, no plating solution has completely eliminated Pb and Cd. Therefore, it is necessary to develop a plating liquid (Pb, Cd-free plating liquid) in which Pb and Cd are completely removed, instead of Pb and Cd.

In addition, in the electroless Ni-P plating, Ni is deposited and plated by reduction, and the conventional plating solution has a large amount of impurities which are reaction products generated during plating. In addition, the life of the plating liquid is short, and the replenishment cycle of the plating liquid is short. This causes an increase in the plating cost, which is undesirable from an environmental point of view because of the large amount of waste liquid. Therefore, the life of the electroless Ni-P plating solution is required to be long.

Republic of Korea Patent Publication No. 10-2004-0002613 Republic of Korea Patent No. 10-1047696 Republic of Korea Patent Publication No. 10-2011-0069265

Accordingly, an object of the present invention is to provide an environment-friendly electroless Ni-P plating solution of Pb, Cd-free, which does not contain Pb and Cd.

In addition, an object of the present invention is to provide a plating method that can reduce the plating cost by extending the use time of the plating liquid.

The present invention to achieve the above object,

In the electroless Ni-P plating solution containing a nickel precursor, a reducing agent, a stabilizer and a brightening agent,

The stabilizer is selected from thio compounds,

The brightening agent provides an electroless Ni-P plating solution that is at least one selected from sodium molybdate, saccharin, thio compounds and naphthalene compounds.

At this time, the thio compound is preferably at least one selected from thioglycolic acid, dithiocholic acid and thiourea.

According to a preferred embodiment, the electroless Ni-P plating solution according to the present invention is based on the total plating solution 1 liter (L) of the nickel precursor 300 ~ 500g / L; Reducing agent 200-300 g / L; Stabilizer 30-60 mg / L; Brightener 15-35 mg / L; Borax 30-45 g / L; Malic acid 30-80 g / L; Adipic acid 50-90 g / L; Lactic acid 40-200 ml / L; And aqueous alkali solution 100-200 ml / L.

In addition, the present invention is a pre-treatment step of degreasing, etching, dismuting and under galvanizing the subject; And

It provides a plating method comprising the step of electroless plating using the electroless Ni-P plating solution of the present invention to the pre-treated target.

At this time, during the electroless plating, it is preferable to immerse a stainless steel rod in a plating solution, and then plate the stainless steel rod as a cathode and the plating vessel as an anode while applying current to the stainless rod and the plating vessel.

In addition, the base galvanizing of the pretreatment step, it is preferable to perform the first zinc gating process to deposit the immersed subject in a zinc treatment liquid of 20 ~ 30 ℃ temperature for 10 to 15 seconds.

According to the present invention, as a stabilizer and a brightener, alternative components of Pb and Cd are included, so that Pb, Cd-freeization is realized. Accordingly, it is possible to overcome the barriers of environmental regulation.

In addition, according to the plating method of the present invention, by extending the use time of the plating liquid has the effect of reducing the plating cost and the amount of waste liquid.

Hereinafter, the present invention will be described in detail.

In the present invention, the "subject" is to be subjected to the electroless Ni-P plating, which includes the semi-finished product, the finished product and the material for the production of the semi-finished product. The subject may be a single metal or alloy, preferably as a metal, for example a single metal such as aluminum (Al), magnesium (Mg), iron (Fe) and copper (Cu) or one or more selected from these It may be an alloy including a metal. In addition, in this invention, the to-be-conducted body may be the metal plated on the surface. For example, a plating layer such as chromium (Cr), zinc (Zn) or copper (Cu) may be coated.

The electroless Ni-P plating solution (hereinafter, abbreviated as 'plating solution') according to the present invention includes a nickel precursor, a reducing agent, a stabilizer and a brightening agent. The plating solution may be composed of an aqueous solution containing at least the above components. The plating solution according to the present invention is a Pb, Cd-free plating solution containing no Pb and Cd. As described above, in the past, Pb compounds as stabilizers and Cd compounds as polishes have been used. However, Pb and Cd are hazardous substances specified by the RoHS.

The plating liquid according to the present invention includes alternative components of Pb and Cd. Specifically, according to the present invention, the stabilizer is selected from thio compounds, and the brightener is one or more selected from sodium molybdate, saccharin, thio compounds and naphthalene compounds.

According to the present invention, thio compounds used as stabilizers have a stabilizing effect equivalent to or higher than that of conventional Pb compounds. That is, the thio compound effectively prevents and stabilizes the spontaneous decomposition and aging of the plating solution to realize a Ni-P plating layer having a uniform thickness. In addition, the above components used as a brightening agent also have a gloss effect equivalent to or higher than that of conventional Cd compounds. That is, excellent glossiness is imparted to the Ni-P plating layer.

In this case, the thio compound may be used as a stabilizer and a brightening agent, and the thio compound is not limited as long as it has a thi group (thio-), but preferably at least one selected from thioglycolic acid, dithiocholic acid and thiourea. good. More preferably, the thioglycolic acid and dithiocholic acid are used as stabilizers, and the thiourea is used as a brightener.

According to the present invention, thioglycolic acid and dithiocholic acid among various thio compounds are very effective for stabilizing plating solution, and thiourea is very effective for gloss. In addition, the brightening agent is selected from sodium molybdate, saccharin, thio compound and naphthalene-based compound as described above, wherein the naphthalene-based compound is not limited as long as it includes naphthalene in the molecule. The naphthalene-based compound may be selected from, for example, naphthalene, 1,5-naphthalene disodium sulfonic acid, 2,6-naphthalene dicarboxylic acid, 2,6-dimethylnaphthalene, and the like.

The plating solution according to the present invention comprises a nickel precursor, a reducing agent, a stabilizer and a brightener as described above, wherein the stabilizer is selected from thio compounds as Pb replacement components, and the brightening agent is sodium molybdate, saccharin, thio compounds as Cd replacement components. And naphthalene compounds, which are environmentally friendly plating solutions containing no Pb and Cd.

The nickel precursor is not limited as long as it is a compound containing nickel (Ni) in the molecule. The nickel precursor can be used, for example, at least one selected from nickel sulfate (NiSO ₄ ), nickel chloride (NiCl ₂ ) and hydrates thereof (NiSO ₄ .6H ₂ O, NiCl ₂ .6H ₂ O). Such nickel precursor may be included in 300 ~ 500g / L based on the total 1 liter (L) of the plating solution. In this case, when the amount (content) of the nickel precursor is less than 300 g / L, the plating amount of Ni is small, and when the amount of the nickel precursor exceeds 500 g / L, an unreacted substance (nickel precursor) may be present in the plating solution (dry bath). The nickel precursor is preferably contained at 390 to 420 g / L based on 1 liter (L) of the total plating solution.

The reducing agent can reduce a nickel precursor, and should just be a compound containing phosphorus (P). The reducing agent may be, for example, one or more selected from sodium hypophosphite, potassium hypophosphite, ammonium hypophosphite and the like as the phosphoric acid compound. The reducing agent may be used by mixing hydrazine (N ₂ H ₄ ) with the above-described phosphoric acid compound. Such a reducing agent may be included in 200 ~ 300g / L based on the total 1 liter (L) of the plating solution. At this time, if the amount (content) of the reducing agent is less than 200 g / L, the unreacted nickel precursor may be present in the plating liquid (dry bath) due to reduction in reactivity, and if it exceeds 300 g / L, the unreacted reducing agent may not be present in the plating liquid (dry bath). May exist. The reducing agent is preferably included at 220 to 260 g / L based on 1 liter (L) of the total plating solution.

The stabilizer is selected from thio compounds as described above, but may be affected by other organic materials such as lactic acid or adipic acid, so that the stabilizer may be included in an amount of 30 to 60 mg / L based on 1 liter (L) of the plating solution. At this time, when the content of the stabilizer is less than 30mg / L, the degree of stabilization of the plating solution according to its content may be insignificant, and when it exceeds 60mg / L, the synergistic effect of excessive use is not so great and the Ni-P plating layer of the The plating rate may be lowered. In view of this, the stabilizer is preferably included in the 35 ~ 55mg / L.

The brightening agent is selected from the compounds as described above, it is preferable to include 15 ~ 35mg / L based on the total 1 liter (L) of the plating solution. At this time, when the content of the polisher is less than 15mg / L, the gloss effect according to its content may be insignificant, and when it exceeds 35mg / L, the synergistic effect of excessive use is not so great, the plating efficiency may be reduced or the plating may be stopped. have. In view of this point, it is preferable that the brightener is included at 20 to 30 mg / L.

In addition, the plating liquid according to the present invention may further include additional components in addition to the above components. Examples of the additional component include at least one selected from a binder, a complexing agent, a pH adjusting agent, a reaction promoter, a pH buffer, and the like. Such additional components are not particularly limited, and those that are commonly used can be used. The additional component may use one or more selected from, for example, organic acids, inorganic acids, salts thereof, and the like.

The bonding agent is for improving the adhesion between the conductor and the Ni-P plating layer, and preferably borax or the like may be used. In addition, the complexing agent is for controlling the rate of reduction, which uses, for example, one or more selected from organic acids such as malic acid (D-malic acid, L-malic acid, DL-malic acid, etc.) and lactic acid (L-lactic acid, etc.). Can be. The pH adjusting agent is for alkalinization of the plating liquid, and for example, an aqueous alkali solution such as ammonia or sodium hydroxide may be used. The reaction promoter is for increasing the plating rate of the plating liquid, which may be selected from, for example, malic acid (D-malic acid, L-malic acid, DL-malic acid, etc.), carbonic acid, and the like. In addition, the pH buffer is for preventing the pH from being rapidly changed by hydrogen ions generated during plating, which may use, for example, an organic acid such as adipic acid.

According to a preferred embodiment, the plating solution according to the present invention is based on the total plating solution 1 liter (L), nickel precursor 300 ~ 500g / L, reducing agent 200 ~ 300g / L, stabilizer 30 ~ 60mg / L, brightener 15 ~ 35mg / L, Borax 30 to 45 g / L, malic acid 30 to 80 g / L, adipic acid 50 to 90 g / L, it is preferable to include lactic acid 40 to 200 ml / L, and alkaline aqueous solution 100 to 200 ml / L. In this case, the plating efficiency of Ni-P is good and a high quality Ni-P plating layer can be formed.

As described above, the plating solution according to the present invention is a Pb-free and Cd-free eco-friendly plating solution containing no Pb and Cd as described above. Overcome In addition, excellent physical properties such as corrosion resistance, abrasion resistance, and chemical resistance required in the plating products to realize a high reliability plating surface, and plated on the surface of the conductor with a uniform thickness.

On the other hand, the plating method according to the present invention includes the step of electroless plating using a plating solution, the plating solution is used as the plating solution according to the present invention as described above.

Specifically, the plating method according to the present invention comprises a pretreatment step of degreasing, etching, dismuting and zinc plating the subject; And electroless plating the pretreated subject by using the plating solution according to the present invention. In addition, after the electroless plating may further comprise a post-treatment step.

At this time, according to a preferred embodiment, in the electroless plating, it is preferable to plate while applying a current to the plating liquid using a rectifier. In this way, when plating while applying current to the plating liquid, the life of the plating liquid can be extended. In addition, in order to extend the life of the plating liquid, it is preferable to minimize the amount of zinc deposited in the base galvanizing (jinkate) of the pretreatment step. Hereinafter, the plating method according to the present invention will be described for each step as follows.

(1) pretreatment

The conductor is pretreated prior to electroless Ni-P plating. The pretreatment includes a degreasing step, an etching step, a dismute step, and a base zinc plating step (jingate step). Each of these steps is preferably performed sequentially. The pretreatment is performed prior to the degreasing process, and may further include a polishing process of sanding the subject. In addition, a washing process may be performed between the processes.

(a) degreasing process

The degreasing process is a process of removing foreign substances and oil components present on the surface of the subject, which can be carried out in the same manner as usual. The degreasing process can be carried out by, for example, depositing a subject in a degreasing liquid. In this case, the degreasing liquid may include at least one selected from sodium hydroxide (NaOH) and a surfactant. The degreasing liquid is preferably a solution containing an anionic surfactant such as ethoxylated nonlyphenol. Anionic surfactants are effective for removing oil components. According to a specific embodiment, the degreasing liquid is sodium carbonate (Na ₂ CO ₃ ) 80 to 150 g / L, sulfuric acid (H ₂ SO ₄ ) 80 to 150 g / L and anionic surfactant 2 based on 1 liter (L) of degreasing solution. It may be composed of an aqueous solution containing ~ 7ml / L.

In addition, the degreasing step may further include an electrolytic degreasing step in the deposition degreasing step. For example, after depositing a subject in a degreasing solution, and performing a degreasing by maintaining for 10 seconds to 30 minutes at a temperature of room temperature ~ 80 ℃, electrolytic degreasing to apply a voltage of 2 ~ 5V under the same conditions You can proceed further.

(b) etching process

An etching process is a process of removing the oxide film etc. formed in the surface of a to-be-conducted object, and this can be performed by a method as usual. The etching process can be carried out, for example, by washing with an alkaline solution or an acid solution. For example, the etching process may be carried out by depositing and cleaning the object subjected to the degreasing process in an acid solution containing sulfuric acid or acetic acid for 10 seconds to 30 minutes, and the acid solution is pH 5-6 A weakly acidic aqueous solution can be preferably used.

(c) Desmut process

The desmut process is a process of removing smut, which is a reducing metal salt formed on the surface of the subject, and can also be carried out in the same manner as usual. The desmert process can be carried out, for example, by a method of washing a subject with a dismist solution. More specifically, the desmut process may be performed by depositing and cleaning the subject subjected to the etching process in a dismert solution at 10 to 80 ° C. for 10 seconds to 30 minutes. At this time, the dismert solution may be used that is commonly used, but is not particularly limited may include, for example, a solution containing at least one selected from nitric acid, hydrofluoric acid, sulfuric acid, iron compounds and ammonium compounds.

(d) Base Galvanizing Process (Jingkate)

The base galvanizing process is a process of forming (substituting) a zinc film on the surface of a subject, and this can also be performed in the same manner as usual. At this time, the activation treatment may be performed before the zinc process. By the activation treatment, the zinc plating (substitution) efficiency can be increased. The activation treatment may be performed by immersing the subject in the treatment liquid, and then activating the surface of the subject by, for example, holding it at a temperature of 50 to 80 ° C. for 2 to 20 minutes. At this time, the treatment liquid used for the activation treatment, for example, based on 1 liter (L) of the total solution may be used an aqueous solution containing a treatment agent such as triethanolamine (TEA) 100 ~ 200g / L.

The base galvanizing process may be constituted by a second method of jinating (Double jinating) as usual. Specifically, the base galvanizing process includes a first zinc gating process (first zinc substitution plating) for depositing a subject in a zinc treatment liquid and a peeling process for removing a zinc film formed by the first zinc gating process. And a second zincating step (second zinc-substituted plating) in which the peeled object is again deposited on the zinc treatment liquid. At this time, the zinc treatment liquid may be used that is commonly used, this may be a solution containing a zinc precursor. The zinc treatment liquid includes, for example, at least a zinc precursor such as zinc sulfate, but includes 25 to 35 g / L of zinc precursor such as zinc sulfate and 100 to 150 g / L of zinc pyrophosphate based on 1 liter (L) of the total treatment liquid. , An aqueous solution containing 2 to 7 g / L of lithium fluoride and 2 to 7 g / L of sodium carbonate can be used.

According to a preferred embodiment of the present invention, the base galvanizing process is not carried out as a double jingkae process (Double jingkae) as described above, it is preferable to proceed to the first jingkae process (single jingkae). Specifically, the process is carried out by a primary scouring process in which a subject is deposited in a zinc treatment liquid. At this time, it is preferable to maintain the temperature of the zinc treatment liquid at 20 to 30 ° C. so that a minimum base zinc plating layer sufficient for Ni-P substitution is formed in the electroless Ni-P plating process. Preferably, the temperature is maintained at a temperature of 22 to 25 ° C. And it is good to carry out by maintaining the deposition for 10 to 15 seconds at such a temperature.

When the base zinc plating is performed by the first gating process (Single gating) in the above temperature and time range, a minimum base galvanizing layer sufficient for Ni-P substitution may be formed. In the electroless Ni-P plating, the amount of zinc ions generated by substitution in the plating solution may be minimized.

According to the present invention, when the base zinc plating is carried out by the above-described first zinc gating process (Single gating), the amount of zinc ions in the plating liquid can be minimized to extend the life of the plating liquid. Specifically, in the electroless Ni-P plating, if there are a lot of impurities such as zinc ions in the plating liquid, the plating liquid is continuously replenished because the electroless Ni-P plating efficiency is lowered due to the decrease in the concentration of active ingredients of the plating liquid such as nickel precursors and reducing agents. You have to do it. However, when the amount of zinc ions is minimized by the above-described primary scouring process (Single gating), the service life of the plating liquid can be extended and the replenishment time of the plating liquid can be delayed. And it is possible to reduce the plating cost due to the replenishment of the plating solution, it is possible to reduce the amount of waste liquid. In addition, it can be made of a single jingkae process (Single jingkae), it is possible to reduce the time of the base galvanizing process than the second jingkae process (Double jingkae), the peeling process and the second jingkae process is excluded The process is simplified.

(2) Electroless Ni -P plating

After the base zinc plating is performed as described above, the Ni-P plating solution is plated on the base zinc plating layer by a conventional electroless plating method. That is, after the Ni-P plating solution is accommodated in the plating bath, the appropriate temperature and time are maintained. At this time, Preferably it is advantageous for plating efficiency to maintain the temperature of a plating tank at 80-95 degreeC, More preferably, it is 82-92 degreeC. And it is good to plate for 10 to 20 minutes.

In the electroless Ni-P plating, it is preferable to apply the rectification method according to a preferred embodiment of the present invention. Specifically, the plating is preferably performed while applying a current to the plating liquid using a rectifier. More specifically, a stainless stick is immersed in a plating solution, and then the stainless steel bar is used as a cathode, the plating bath is used as an anode, and a rectifier is connected to the stainless steel bar (cathode) and the plating bath (anode) to supply current. It is good to plate while applying.

According to the present invention, when plating while applying a current to the plating liquid during electroless Ni-P plating as described above, it is possible to extend the life of the plating liquid. Specifically, the plating solution contains zinc ions, nickel ions, aluminum ions, magnesium ions, copper ions, iron ions, etc. derived from the conductor as impurities such as metal ions, and the like. In this case, a metal having a larger ionization tendency than nickel is precipitated on the stainless steel rod serving as the cathode. For example, magnesium, aluminum, zinc, iron and nickel are precipitated in the stainless steel rod. At this time, magnesium and aluminum are derived from the components of the specimen material, they are precipitated in a small amount, mainly zinc is deposited on the stainless steel rod.

As described above, when there are many impurities such as metal ions in the plating liquid, electroless Ni-P plating efficiency is lowered due to a decrease in the concentration of active ingredients of the plating liquid such as nickel precursors and reducing agents, so that the plating liquid must be continuously replenished. When the plating is applied while applying current, metal ions are precipitated and removed on the stainless steel rod, thereby extending the service life of the plating liquid and delaying the replenishment timing of the plating liquid. In addition, it is possible to reduce the plating cost due to the replenishment of the plating solution, and reduce the amount of waste liquid.

At this time, in applying the current through the rectifier, it is preferable to apply a low current. Specifically, it is good to apply a current of 0.05 ~ 2.0A. Applying such a low current can minimize the amount of nickel deposited on the stainless steel rod. That is, when a current lower than the current at which nickel is deposited is applied, metal ions such as zinc, which is faster than nickel, are precipitated on the stainless steel rod, thereby effectively removing impurities in the plating solution.

In addition, while applying a current of 0.05 ~ 2.0A, it is good to energize for a long time. For example, it is good to make it energize for 10 minutes or more, specifically 10 minutes-20 minutes. In addition, as described above, when the current is applied, the plating bath becomes an anode, wherein the plating bath is preferably made of SUS (for example, SUS316). When the plating bath (anode) is made of SUS material, the plating bath can be passivated to prevent the precipitation of nickel.

(3) Postprocessing

The plating method according to the present invention may further include a post-treatment step that proceeds after the electroless Ni-P plating step. The aftertreatment step is an optional process. The post-treatment may include, for example, one or more selected from discoloration prevention processes and heat treatment processes.

The discoloration prevention process is to prevent discoloration of the Ni-P plating layer, which may be performed through chemical treatment. The discoloration prevention process may be performed by, for example, depositing a Ni-P plated object in an aqueous solution containing a discoloration inhibitor. This discoloration prevention process may be performed, for example, for 1 to 5 minutes, and the discoloration preventing agent may use one or more selected from, for example, potassium pyrophosphate, sodium triphosphate, and the like.

In addition, the heat treatment process is a process for improving the adhesion between the base galvanized layer and the Ni-P plated layer of the object, which is to be carried out in a method of applying a heat of 150 ℃ or more, specifically 150 ~ 300 ℃ temperature Can be. Such heat treatment is not particularly limited, but may be performed for 10 minutes to 1 hour.

According to the plating method of the present invention described above, while the high-quality Ni-P plating layer is precisely plated with a uniform thickness on the surface of the subject, the process is simple and the plating time is short. In particular, as described above, in the case of electroless plating, when plating is applied while applying a current to the plating liquid, or when the base zinc plating process is performed by the first gating process (Single gating), the plating liquid can be extended in life and the plating liquid can be replenished. You can slow it down. Accordingly, the plating cost can be reduced, and the amount of waste liquid can be reduced, which is advantageous in terms of the environment.

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

Example 1

< Electroless Ni -P Plating Solution>

A, B and P agents were prepared in the components and contents as shown in the following [Table 1]. Then, first agent B and P agent were mixed to obtain agent M, and then 50 mL / L agent A was mixed with 100 mL / L of agent M to prepare an electroless Ni-P plating solution. In Table 1 below, the content of the plating liquid is based on 1 L of the entire plating liquid, and the remaining amount is water.

At this time, in case of B agent, sodium hypophosphite, DL-malic acid, adipic acid, and L-lactic acid are mixed, and 45 g of tiglycolic acid is used as a stabilizer. / L and 25 ml / L of thiourea as a brightening agent were added.

< Subject  Pretreatment>

An aluminum alloy (hereinafter referred to as 'Al specimen') was prepared as a conductor for electroless Ni-P plating. The prepared Al specimens were degreased, etched, desmitted, and ground zinc plated (zincate) as follows.

First, the Al specimen was degreased by dipping for 10 minutes in a degreasing solution containing an anionic surfactant (ethoxylated nonylphenol). And the degreasing Al test piece was immersed in the etching liquid of the weakly acidic aqueous solution for about 40 second, and was etched. Next, the etched Al specimens were immersed in a mixed solution of nitric acid and hydrofluoric acid for 40 seconds and then immersed.

As described above, the Al specimens subjected to the immersion treatment were subjected to base galvanizing (jinging), but not carried out over a double as in the prior art but carried out over a single. Specifically, the immersed Al specimen was dipped in the zinc treatment liquid for 12 seconds to plate (substitute) zinc on the surface of the Al specimen. (Single gating) At this time, the zinc treatment liquid was treated with 1 liter of the whole treatment liquid ( Based on L), an aqueous solution containing 30 g / L zinc sulfate, 120 g / L potassium pyrophosphate, 5 g / L lithium fluoride, and 5 g / L sodium carbonate was used, and the temperature of the zinc treatment solution was maintained at 23 ° C.

< Electroless Ni -P Plating>

The plating solution prepared above was accommodated in a plating bath, and then the base galvanized Al specimens were deposited in the plating solution. And the plating liquid was kept at 90 degreeC, and electroless Ni-P plating was performed for 15 minutes. At this time, in order to remove impurities such as metal ions in the plating solution during electroless Ni-P plating, plating was performed while energizing using a rectifier as follows.

Specifically, the plating bath was made of SUS316 material, and the stainless steel rod was immersed in the plating solution. A positive electrode of the plating bath (SUS316) was used as the negative electrode, and the positive electrode (plating bath) and the negative electrode (stainless steel bar) were energized by a rectifier to flow a 0.1 A current into the Ni-P plating solution. At this time, it was found that metal ions were deposited on the stainless steel rod that is the cathode.

In addition, after plating Ni-P as described above, the plating specimen was immersed in an aqueous potassium pyrophosphate solution for 3 minutes to perform a discoloration prevention treatment. Then, the plated specimen treated with discoloration was placed in an electric oven, and further heat-treated at 180 ° C. for 20 minutes.

 [Example 2]

In preparing the electroless Ni-P plating solution, as shown in the following [Table 1], it was carried out in the same manner as in Example 1 except that the stabilizer and the brightener were different. Specifically, in forming the agent B, dithioglycolic acid was used as a stabilizer, and sodium molybdate was used as a brightener.

After the pretreatment was carried out in the same manner as in Example 1, electroless Ni-P plating was performed while flowing a current through the rectifier through a plating solution.

 [Comparative Example]

< Electroless Ni -P Plating Solution Manufacturing>

The electroless Ni-P plating solution most commonly used is prepared. The components and contents of the plating solution according to the comparative example are shown in the following [Table 1]. As shown in [Table 1], the plating solution is composed of A agent, B agent, and P agent. At this time, in the case of agent B, the first additive contains a small amount of Pb compound as a stabilizer, and the second additive contains a small amount of Cd compound as a brightening agent.

< Subject  Pretreatment>

The same Al specimens as in Example 1 were degreased, etched, desmitted, and ground zinc plated. Degreasing, etching, and dismuting were performed in the same manner as in Example 1. And in the case of base zinc plating (jinkate), it performed over 2nd (Double) as usual.

Specifically, for the immersed Al specimens, zinc was first deposited on the surface of the Al specimens by first immersion in a zinc treatment solution at 60 ° C. for 15 seconds (primary gilding process). Thereafter, zinc was removed (peeling process) by dipping in a mixed solution of hydrofluoric acid and nitric acid for 10 seconds. Then, the peeled specimen was again immersed in the zinc treatment liquid at 60 ° C. for 15 seconds to perform zinc secondary substitution plating (secondary quenching process). (Double jincate) At this time, the first and second secondary Zinc treatment solution used in the same as in Example 1.

< Electroless Ni -P Plating>

The pretreated Al specimens were subjected to electroless Ni-P plating in the same manner as usual. Specifically, during electroless Ni-P plating, electroless Ni-P plating was performed for 20 minutes at 50 ° C. as usual without energizing a rectifier.

                <Components and Contents of Electroless Ni-P Plating Solution> Remarks Example 1 Example 2 Comparative example A Nickel Sulfate 410 g / L Nickel Sulfate 410 g / L Nickel Sulfate 410 g / L L-lactic acid 45ml / L L-lactic acid 45ml / L L-lactic acid 45ml / L Borax 37g / L Borax 37g / L Borax 37g / L B Sodium hypophosphite 240 g / L Sodium hypophosphite 240 g / L Sodium hypophosphite 510 g / L DL-Malic Acid 50 g / L DL-Malic Acid 50 g / DL-Malic Acid 25 g / Adipic acid 70 g / L Adipic acid 70 g / L Adipic acid 70 g / L L-lactic acid 100ml / L L-lactic acid 100ml / L L-lactic acid 100ml / L Thioglycolic acid 45mg / L Dithioglycolic acid 45mg / L First Additive 5ml / L Thiourea 25mg / L Sodium molybdate 25mg / L Second Additive 15 ml / L P ammonia 140ml / L ammonia 140ml / L NaOH aqueous solution 140ml / L M B + P B + P B + P

For the electroless Ni-P plating solutions according to the above Examples and Comparative Examples, a toxic substance (heavy metal) analysis test was performed, and the results are shown in the following [Table 2]. In addition, for the plating specimens according to the above Examples and Comparative Examples, the stability and glossiness were evaluated and the results are shown in the following [Table 3].

At this time, the degree of stabilization was evaluated by a method of measuring the thickness of the same position by selecting any three specimens in one jig (JIG) of the plating bath according to each Example and Comparative Example, the glossiness is typically It evaluated according to KS A 0069 (60 degree Gloss standard) which is the glossiness measurement method used.

             <Component Analysis of Electroless Ni-P Plating Solution> Item Example 1
(mg / L) Example 2
(mg / L) Comparative Example
(mg / L) Analysis method Pb (Lead) N.D. N.D. 2.9 IEC 62321: 2008, ICP Cd (Cadmium) N.D. N.D. 0.3 IEC 62321: 2008, ICP Hg (Mercury) N.D. N.D. N.D. IEC 62321: 2008, ICP Cr (Chrome) N.D. N.D. N.D. IEC 62321: 2008, UV-Vis. Sb (Antimony) N.D. N.D. N.D. EPA 30521: 1996, ICP

                 <Stabilization and gloss evaluation results> Item Example 1 Example 2 Comparative example Stabilization 2.61 2.94 2.87 2.74 2.87 2.69 2.94 2.67 2.81 Standard deviation 0.14 Standard deviation 0.2 Standard deviation 0.11 Glossiness 109 104 106 91 90 92 98 96 87 Average 106 Average 91 Average 94

First, as shown in [Table 2], in the case of the plating solutions according to Examples 1 and 2 of the present invention, it can be seen that Pb and Cd-freeization were achieved as Pb and Cd were not detected (ND). However, in the case of the comparative example according to the conventional conventional plating liquid composition, a small amount of Pb and Cd was detected. In addition, as shown in Table 3, it can be seen that Examples 1 and 2 of the present invention have a degree of stability or glossiness equivalent to or higher than that of a conventional comparative example.

On the other hand, during the electroless plating in the embodiment of the present invention, a material such as metal ions was deposited on the stainless steel rod as a current is applied, the following Table 4 is a component of the material deposited on the stainless steel rod in Example 1 The analysis results are shown.

        <Component analysis result of material deposited on stainless steel rod> ingredient Zn O Mg Al P Ni Weight% 56.53 28.27 0.65 4.13 0.53 9.89

As shown in Table 4 above, impurities such as metal ions were deposited on the stainless steel rod during electroless plating. In particular, the amount of precipitation of zinc was large. This means that impurities in the plating liquid have been removed.

In addition, Table 5 below shows the results of Zn and Ni content during electroless plating. At this time, the following [Table 5] is based on the MTO (Metal Turn Over: time of replenishing the nickel precursor of the same concentration in the plating process) of the plating bath.

       <Content of Zn and Ni based on MTO in electroless plating> Item ingredient Comparative Example
(mg / L) Example 1
(mg / L) 0 MTO Zn 16 22 Ni 1754 2059 1 MTO Zn 50 36 Ni 1304 1596 1.5 MTO Zn 65 48 Ni 1172 1307 2 MTO Zn - 50 Ni - 1555 3 MTO Zn - 56 Ni - 1202

As shown in Table 5, in the case of the comparative example, the amount of Zn was increased so that only good products were plated up to 1.5 MTO, but in the case of the embodiment of the present invention, the amount of Zn was reduced and the amount of good was plated up to 3 MTO. This is due to the application of the current of the plating solution during electroless plating and the first gating process (single gating) performed in the pretreatment, thereby prolonging the lifetime by removing metal ions such as Zn from the plating solution or minimizing the amount of production. Because.

As can be seen in the above experimental example, according to the present invention, Pb, Cd-freeization can be realized by replacing Pb and Cd with stability and glossiness equivalent to or higher than that of the related art. In addition, the life of the plating liquid can be implemented to reduce the plating cost and reduce the amount of waste liquid.

Claims (6)

In the electroless Ni-P plating solution containing a nickel precursor, a reducing agent, a stabilizer and a brightening agent,
The stabilizer is selected from thio compounds,
The brightening agent is an electroless Ni-P plating solution, characterized in that at least one selected from sodium molybdate, saccharin, thio compounds and naphthalene compounds.
The method of claim 1,
The thio compound is an electroless Ni-P plating solution, characterized in that at least one selected from thioglycolic acid, dithiocholic acid and thiourea.
The method of claim 1,
The electroless Ni-P plating solution may be selected from the group consisting of 300 to 500 g / L of nickel precursor based on 1 liter (L) of the plating solution; Reducing agent 200-300 g / L; Stabilizer 30-60 mg / L; Brightener 15-35 mg / L; Borax 30-45 g / L; Malic acid 30-80 g / L; Adipic acid 50-90 g / L; Lactic acid 40-200 ml / L; And an aqueous alkali solution of 100 to 200 ml / L.
A pretreatment step of degreasing, etching, dismuting and galvanizing the subject; And
Plating method comprising the step of electroless plating on the pre-treated target object using the electroless Ni-P plating solution according to any one of claims 1 to 3.
5. The method of claim 4,
In the electroless plating, a plating method comprising immersing a stainless steel rod in a plating solution, and then plating the stainless steel rod and the plating tank while applying a current to the stainless steel rod and the plating bath, with the stainless steel rod as the cathode and the plating vessel as the anode.
The method according to claim 4 or 5,
The base galvanizing is a plating method, characterized in that to perform the first zinc gating process to deposit the immersed subject in a zinc treatment liquid of 20 ~ 30 ℃ temperature for 10 to 15 seconds.