KR101736300B1

KR101736300B1 - Electroless silver plating solution and it used silver plating method

Info

Publication number: KR101736300B1
Application number: KR1020150111571A
Authority: KR
Inventors: 고창규; 이영용
Original assignee: 아트켐 주식회사
Priority date: 2015-08-07
Filing date: 2015-08-07
Publication date: 2017-05-17
Also published as: KR20170018228A

Abstract

The present invention relates to a plating solution for electroless silver plating and an electroless plating method using the same, which comprises a step of preparing and cleaning a metal material, a step of cleaning a metal material such as silver nitrate (AgNO ₃ ), a copper salt, a nickel salt, , A discoloration inhibitor and a surfactant, comprises immersing, washing and drying the cleaned metal material in a plating solution. Thus, the present invention provides a method for cleaning a metal material to be plated, (Ni) or copper (Cu), and a reducing agent is deposited, washed and dried in a plating solution to form an initial silver plating layer through an initial substitution reaction during formation of a silver plating layer, The plating layer can be relatively thickly plated.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating solution for electroless silver plating,

The present invention relates to an electroless silver plating solution capable of forming silver (Ag) having a relatively large thickness by a chemical substitution and reduction method, and a method of electroless silver plating using the same.

As is well known, the demand for lead frames used for LEDs has been rapidly increasing recently, and the demand for silver plating has also been increasing.

Accordingly, in order to reduce the use of silver (Ag), which is a noble metal, research and development has been going on to apply the plating method not the front plating but the conventional alkaline substitution or electrolytic silver plating, Plating resist (dry film) can not withstand the plating solution and is peeled off, so an acidic silver plating solution is required.

In addition, unlike the method of attaching the conventional silver nanoparticles to the fiber in the technical field of producing the most advanced antibacterial fiber by plating pure silver (Ag) having a purity of 99.9% or more in the nylon yarn, the nano- In order to decrease the defect rate and to increase the yield in the production of high-tech materials that have antimicrobial and anti-seizing properties, the acid electroless plating has been researched and developed for the application of plating.

1. Registered Patent No. 10-11110397 (Registered Jan. 19, 2012): Plated material formed by electroless plating and metal thin film and method of manufacturing the same 2. Registered Patent No. 10-1431491 (Registered on December 14, 2014): Electroless gold plating method and electronic parts

The present invention provides an electroless silver plating solution capable of forming silver (Ag) having a relatively large thickness by a chemical substitution and reduction method, and a method of electroless silver plating using the same.

The present invention also relates to a method for producing a silver plating layer by washing a metal material to be plated and then immersing, cleaning and drying the silver (Ag), nickel (Ni) or copper (Cu) The present invention provides an electroless silver plating solution and an electroless silver plating method using the electroless silver plating solution capable of initially forming a plating layer through an initial substitution reaction and then plating the plating layer to a relatively thicker thickness through a reducing agent.

In addition, the present invention provides a plating solution for electroless plating which can impart wire bonding properties and can improve the conductivity and antibacterial property by forming the initial silver plating layer formed through the substitution reaction relatively thicker by the reducing agent, The electroless silver plating method is intended to provide a plating method.

The objects of the embodiments of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description .

According to one aspect of the present invention, an electroless silver plating solution may be provided, which includes silver nitrate (AgNO ₃ ), copper (Cu) salt, nickel (Ni) salt, reducing agent, chelate, anticorrosion agent and surfactant.

According to another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: preparing and cleaning a metal material; and electroless plating including a silver nitrate (AgNO ₃ ), a copper (Cu) salt, a nickel (Ni) salt, a reducing agent, a chelate, Silver plating method using electroless silver plating solution may be provided, which comprises immersing, washing and drying the cleaned metal material in a plating solution.

The present invention can form silver (Ag) having a relatively large thickness by a chemical substitution and reduction method. Specifically, the metallic electroless solution containing silver (Ag), nickel (Ni) or copper (Cu) and a reducing agent and a discoloration inhibitor is washed, immersed in a plating solution, washed and dried, The initial plating layer may be formed through the initial substitution reaction during the formation of the plating layer, and then the initial plating layer may be relatively thickly plated through the reducing agent.

Also, since the initial silver plating layer formed through the substitution reaction is relatively thickened by the reducing agent, the wire bonding property can be imparted, and the improved conductivity and antibacterial property can be improved.

FIG. 1 is a flowchart showing a process of performing silver plating using electroless silver plating solution according to another embodiment of the present invention, and FIG.
FIG. 2 is a view illustrating a substitution reaction and a reduction reaction for silver plating according to another embodiment of the present invention,
FIG. 3 is a view illustrating plating on a fabric in a silver plating process according to another embodiment of the present invention.

Advantages and features of embodiments of the present invention and methods of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions in the embodiments of the present invention, which may vary depending on the intention of the user, the intention or the custom of the operator. Therefore, the definition should be based on the contents throughout this specification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The electroless silver plating solution according to an embodiment of the present invention may include silver nitrate (AgNO ₃ ), copper (Cu) salt, nickel (Ni) salt, reducing agent, chelate, anticorrosion agent and surfactant, The range can have about 1.0-4.0.

Here, the electroless silver plating solution is a silver nitrate solution (AgNO ₃ ) at a concentration of 1-20 g / l, a copper (Cu) salt at a concentration of 0.1-5 g / l, a nickel (Ni) at a concentration of 0.1-10 g / l, at a concentration of 10-100 g / l of a chelate, at a concentration of 0.1-10 g / l of a discoloration inhibitor, 0.1-5 g of a surfactant, / l. < / RTI >

It is needless to say that the chelate as described above can be replaced by Rochelle salt, EDTA and the like.

The reducing agent as described above may include at least one selected from formaldehyde (HCHO), DMAB (DIMETHYLAMINE BORANE), and hydrazine, and the anticorrosion agent may include BOT (Benzotriazole) or a derivative thereof .

Therefore, the present invention can form silver (Ag) having a relatively large thickness by a chemical substitution and reduction method, which can quickly and easily form a plating layer, and can be formed with a thickness of about 1.5-3 탆 The silver plating layer can be formed.

In addition, the present invention can form a uniform silver plating layer having advantages such as superior working yield, soldering characteristics, and long-term reliability through plating by substitution and reduction, and there is no unnecessary loss time at the time of work, It is possible to reduce the cost in the treatment of wastewater, and it is possible to provide an electroless plating solution with stable and stable lifetime.

In addition, since the present invention can be commonly used for Pb-free solder and Sn / Pb solder paste, it has excellent compatibility with excellent soldering characteristics, and has excellent electric conductivity and low ion contamination. (Pb-free) regulations of RoHs (Restriction of Hazardous Substances) and WEEE (Waste Electrical and Electronic Equipment) as well as to improve solderability and solderability. It has an advantage that it is excellent in environmental friendliness.

Next, the electroless plating method for forming the silver plating layer on the metal material using the plating solution as described above will be described in detail.

FIG. 1 is a flowchart showing a process of performing silver plating using electroless plating solution according to another embodiment of the present invention. FIG. 2 is a flow chart showing steps of substitution reaction and reduction reaction for silver plating according to another embodiment of the present invention. Fig.

Referring to FIGS. 1 and 2, the electroless plating metal material to be plated is prepared (step 102).

Here, the metal material may include at least one powder selected from among copper (Cu), nickel (Ni), bronze, brass, and zinc (Zn).

Then, the prepared metal material is cleaned (step 104). This cleaning can be performed at 30-50 ° C using pure water (DI water) with a purity of at least 1 MΩ.

Next, an electroless plating solution having an acidity is prepared (step 106). The electroless silver plating solution may include silver nitrate (AgNO ₃ ), copper (Cu) salt, nickel (Ni) salt, reducing agent, chelate, anticorrosion agent and surfactant, and its pH range may be about 1.0-4.0 have.

The reducing agent as described above may include at least one selected from the group consisting of formaldehyde (HCHO), DMAB (DIMETHYLAMINE BORANE) and hydrazine, and the anticorrosion agent may include BOT (Benzotriazole) or a derivative thereof , The chelate may be replaced by Rochelle salt, EDTA, and the like.

Next, the electroless plating solution having the acid precipitates, rinses and dries the metal material in the plating solution (step 108). Here, the immersion process can be carried out by immersing at 50-70 DEG C for 1-5 minutes, and during the immersion, electroless plating reaction involving a substitution reaction and a reduction reaction takes place.

This substitution reaction and reduction reaction will be described in more detail with reference to FIG. 2. The substitution reaction (a) is referred to as 'immersion plating'. The difference in ionization tendencies of different metals (that is, (M1) material that is electrochemically opaque (that is, easy to melt) is immersed in a solution containing electrochemically valuable (i.e., poorly soluble) metal (M2) ions, The electrons may be transferred to the noble metal ions in the solution and a coating of the noble metal may be formed on the surface of the non-metal. For example, copper may be plated on a piece of iron immersed in a copper sulfate solution.

Here, the displacement plating is referred to as " deposition plating " since the plating operation is to deposit the object to be plated in the metal salt solution.

The plated film as described above is very thin and has many pin holes and is not widely used because it is inferior in adhesion with the material. It is used only in special cases because the surface of the metal (M1) The metal M1 is not exposed to the plating solution and the substitution reaction does not occur.

On the other hand, the chemical reduction reaction (b) is a plating obtained by bringing a plating solution into contact with a solution in which a metal salt and a soluble reducing agent (R) coexist. The electrons released by oxidation of the reducing agent are transferred to metal ions to form a metal coating The tissue phase is similar to immersion plating, but the principle is called chemical reduction plating because it is based on chemical reduction, and is called electroless plating in a narrow sense because it is not carried out by electric force.

Through the substitution reaction as described above, an initial silver plating layer in the range of 0.01-1 탆 can be formed, and a silver plating layer having a thickness of 3-5 탆 is formed through the reduction reaction, so that the final silver plating layer has a thickness range of 3-6 탆 Lt; / RTI >

And, the cleaning process can be performed by cleaning at 30-50 ° C using pure water (DI water) with a purity of at least 1 MΩ.

In addition, the drying process may be performed by applying a pressure of 1-5 Kg / cm 2 at 40-80 ° C through a hot air drier.

The plated layer may be formed to a thickness of approximately 3-6 [mu] m through the above-described process.

Accordingly, the present invention provides a method for producing a silver plating layer by cleaning a metal material to be plated and then performing the acidic electroless plating including silver (Ag), nickel (Ni) or copper (Cu) The initial plating layer may be formed through the initial substitution reaction, and then the initial plating layer may be relatively thickly plated through the reducing agent.

In addition, since the initial silver plating layer formed through the substitution reaction is relatively thickened by the reducing agent, the wire bonding property can be imparted, and the improved conductivity and antibacterial property can be improved.

FIG. 3 is a view illustrating plating on a fabric in the silver plating process according to another embodiment of the present invention. In the case of plated using a substitution and reduction reaction on a copper foil, which is a plated microfiber sheet, , It can be seen that the color is bright and is formed almost similar to the color inherent in silver.

Next, various management conditions and analysis methods for performing the chemical silver plating chemistry described above will be described in detail. First, according to the pre-dip conditions shown in Table 1 below, the working temperature is maintained Can be managed.

Product name standard Management scope D.I water Pure conforming standard 35-45 ℃

Here, pure water (DI water) is maintained at a resistance of at least 1 M OMEGA, and pure water is put into the tank, and the temperature is maintained at about 40 ° C. Exchangeable.

The silver plating solution can be maintained under the conditions shown in Table 2 below.

Product name Humidity standards Management scope D.I water Proper balance Purity: Use at least 1㏁ A 200 ml / l 180-220 B 50 ml / l 40-60 C - Ag concentrate concentrate

A is a chemical used as a main material in silver plating using a plating solution, and may include basic silver (Ag), a chelate, a copper salt, a discoloration inhibitor, etc., and B may contain a main reducing agent , And C may contain a high concentration of silver (Ag).

For example, add 1/2 of the tank's pure water, add the A agent, warm to about 40 ° C, add the B agent, adjust the balance volume with pure water, Heated and maintained. In this case, it is preferable to use pure water rather than a constant in order to prevent partial discoloration or the like in the primary washing performed after plating.

On the other hand, the silver plating operation requires the working conditions as shown in Table 3 below and the facilities as shown in Table 4 below.

division standard range Temperature 58 ℃ 55-63 ° C pH 1.25 1.0-2.0 Plating rate - Approximately 1.5-2.0 [mu] m / 2 min filter - 5-10 [mu] m cartridge (continuous circulation filtration) Stirring - Solution circulation and mechanical agitation are performed to maintain uniform plating rate Other references - If the temperature of the solution drops below 40 ℃ after the operation is stopped, it may cause sediment on the floor. However, when it is heated to the working temperature again, it becomes a normal liquid state. (In case of redissolution, Can be redone and then down to the operating temperature)
- silver (Ag) is supplemented by analysis of consumption during work

division Requirements Tank - PP (SUS, metal materials are prohibited for Pre-Dip and Ag Tank) exhaust - recommend heater - PTFE, Teflon, Quartz filter - Using PP Cartridge (using 10 ㎛ Filter) Stirring - uniform and mild agitation, prohibition of air use (prevention of inflow by filter) Pump - CPVC, PP, PTFE, Ceramic

On the other hand, in the case of Ag Tank, when supplementing the solution, supplement the solution of agent A and replenish agent B at a ratio of 4: 1 when supplementing agent A.

Second, the Ag thickness is measured with an X-ray thickness gauge using a regular specimen of Pad Size 2.25 ㎟. The main factors of thickness are influenced by Ag concentration, liquid agitation and temperature, Mu m, and thus can have excellent solderability, small contact resistance, and strong corrosion resistance.

Third, in the case of Ag ion supplementation, AA (Atomic Absorption Spectroscopy) analysis is performed and C drug is replenished, and C drug: B drug can be supplemented at a ratio of 1: 0.5.

Fourth, when the electroless silver plating solution is replaced, the copper (Cu) concentration is more than 3,000 ppm or the liquid color is dark blue at 15 MTO, and the reconstruction bath can be performed when the reaction is slow.

Fifth, pure water to be used in humidification must be checked in advance for purity (minimum 1 ㏁ or more) to prevent deterioration of plating solution performance due to impurities.

Next, the analytical method will be described in detail. First, Ag concentration is measured using AA (Atomic Absorption Spectroscopy), Ag + 2, 5 and 10 ppm standard reagents. 5, and 10 ppm, and diluted with pure water (DI water) at a ratio of 1: 100, and the diluted plating solution was measured using AA to determine the value of Aag As shown in FIG.

Here, the concentration is calculated under the condition of 'Ag concentration (ppm) = Aag * 100', and the replenishment amount 'C drug (ml) replenishment amount = (1400 - measured concentration (ppm)) * (Tank Vol) / 63' . &Lt; / RTI >

Second, the standard concentration of Cu2 +, Cu2 +, Cu2 +, Cu2 +, Cu2 +, Cu2 +, Cu2 + and Cu + 250 dilution with pure water (DI water), and recording the value of Acu while measuring the diluted plating solution using AA.

Here, the concentration can be calculated under the condition of 'Cu concentration (ppm) = Acu * 250'.

For the A drug, 0.05 M copper nitrate solution was prepared by dissolving Copper Nitrate Hemipentahydrate crystals in 500 ml of pure water, transferring the solution to 1 liter volumetric flask, and adding 1 liter of pure water. (Acetate Buffer Solution) is prepared by dissolving 68.0 g of Sodium Acetate Trihydrate and 30.0 g of Glacial Acetic Acid in 500 ml of pure water and requires a PAN indicator.

These A drugs are prepared by cooling the working plating solution to approximately 15-25 ° C., then collecting 15 ml of the solution in a 250 ml Erlenmeyer flask, adding 25 ml acetate buffer solution, then adding 100 ml pure water, and adding 6 drops of PAN indicator And analyzed in a titration fashion until the 0.05 cup silver nitrate silver solution becomes yellow to purplish.

Here, the concentration is' Free Complexant (M) = ml of Copper Nitrate Solution * 0.05M * 0.067 '→' Total Complexant (M) = Free Complexant + {Cu Concentration (ppm) * 1.574 * 10-5} A (%) = Total Complexant * 555 '. In the case of replenishment, it is necessary to replenish a quarter of the amount of the B drug with respect to the amount of the A drug replenishment.

In order to treat the plating solution, the electroless plating solution described above can be decomposed by removing heavy metals or the like with a sufficient amount of air from the working plating solution or by adding a polymer flocculant or the like. In order to treat the cleaning solution, sufficient neutralization with NaOH or copper precipitation Completely removed.

Meanwhile, in another embodiment of the present invention as described above, the process of silver plating the metal material using the plating solution has been described in the acid electroless plating process. However, the present invention is applicable to the PCB process for the final process of the circuit board and the wire bonding, The chemicals for conductivity and anti-discoloration function during surface treatment to provide electrical characteristics of copper, nickel, and aluminum powder are widely used in various industries such as plating applications, EMI shielding sheets, antibacterial equipment, Field.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be readily apparent that such substitutions, modifications, and alterations are possible.

Claims

An electroless silver plating solution comprising a silver nitrate (AgNO ₃ ), a copper (Cu) salt, a nickel (Ni) salt, a reducing agent, a chelate, an anticorrosion agent and a surfactant and having a pH range of 1.0-4.0.

The method according to claim 1,
Wherein the electroless silver plating solution is a silver plating solution in which the silver nitrate (AgNO ₃ ) is 1-20 g / l, the copper salt is 0.1-5 g / l, the nickel salt is 0.1-3 g / The electroless solution containing the reducing agent in an amount of 0.1 to 10 g / l, the chelate in an amount of 10 to 100 g / l, the anti-discoloring agent in an amount of 0.1 to 10 g / l and the surfactant in a concentration of 0.1 to 5 g / Plating solution.

3. The method of claim 2,
Wherein the reducing agent comprises at least one selected from the group consisting of formaldehyde (HCHO), DMAB (DIMETHYLAMINE BORANE) and hydrazine,
Wherein the color fading agent comprises BTA (Benzotriazole) or a derivative thereof.

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Preparing a metal material and cleaning it at 30-50 DEG C with pure water (DI water) with a purity of at least 1 M [Omega]
Electroless electrolysis, which includes a silver nitrate (AgNO ₃ ), a copper (Cu) salt, a nickel (Ni) salt, a reducing agent, a chelating agent, a discoloration inhibitor and a surfactant, and having a pH range of 1.0-4.0, , Washing and drying
Wherein the electroless plating is performed using a plating solution.

The method according to claim 6,
The dipping, washing and drying step is carried out by immersing at 50-70 ° C for 1-5 minutes, washing at 30-50 ° C with pure water (DI water) at a purity of at least 1 MΩ, A silver plating method using electroless silver plating solution which is dried by applying a pressure of 1-5 Kg / cm < 2 >

8. The method according to claim 6 or 7,
Wherein the electroless silver plating solution is a silver plating solution in which the silver nitrate (AgNO ₃ ) is 1-20 g / l, the copper salt is 0.1-5 g / l, the nickel salt is 0.1-3 g / The electroless solution containing the reducing agent in an amount of 0.1 to 10 g / l, the chelate in an amount of 10 to 100 g / l, the anti-discoloring agent in an amount of 0.1 to 10 g / l and the surfactant in a concentration of 0.1 to 5 g / Silver plating method using a plating solution.

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