KR100453913B1 - METHOD OF ELECTROLESS Ni PLATING ON Pb-BASED CERAMICS - Google Patents

Abstract

The present invention relates to a Pb-based ceramic electroless Ni plating method, which degreasing the ceramics with CH ₃ OH or NaHCO ₄ solution, the degreased ceramics with HBF ₄ solution of 0.1-5.0% concentration. Etching, catalyzing the etched ceramics with a Pd-Sn solution containing 25 to 200 mL / L of HCl, and reacting the catalyzed ceramics with a H ₂ SO ₄ solution at a concentration of 5 to 20%. Accelerating with and electroless Ni plating using the Ni salt at a pH of 8.0 to 10.0 and a temperature of 70 to 100 ° C.

The electroless Ni plating method of the present invention significantly improves the adhesion and the electrical contact between the base and the plated layer has an effect of high practicality as an electroless Ni plating method on a Pb-based ceramic matrix.

Description

Electroless nickel plating method of lead-based ceramics {METHOD OF ELECTROLESS Ni PLATING ON Pb-BASED CERAMICS}

[Industrial use]

The present invention relates to an electroless Ni plating method of Pb-based ceramics, and more particularly, to an electroless Ni plating method of Pb-based ceramics having excellent adhesion and electrical contact between the base and the plating layer.

[Private Technology]

The method of forming an electrode in Pb-based ceramics, in particular PZT (lead zirconate titanate: PbZrO ₃ -PbTiO ₃ or PbTi _0.48 Zr _0.5 2O ₃ ), includes a paste method, a dry plating method (PVD), and a wet plating method (electroless plating). . Precious metals such as Ag, Pd, Pt, Cu, and the like are used in the paste method, and Cu and Ni are mainly used in the dry and wet plating methods.

The most commonly used method is the paste method of Ag or Pd because of excellent properties such as heat resistance, environmental resistance, electrical conductivity, solderability, adhesion. However, this method requires a heat treatment at a high temperature, and the phenomenon of diffusion of the precious metal for the electrode into the substrate often occurs with the distortion of the PZT substrate. In addition, there is a disadvantage in that the process is difficult when coating on a substrate of a complex shape. On the other hand, the dry plating method is inferior in adhesion, compared to other plating methods, there is a disadvantage that the initial equipment cost is high, the operating conditions are difficult, and the bulk plating is impossible to possess a complex shape.

On the other hand, the electrode formation by the electroless plating method, which is a wet plating method, is excellent in heat resistance, environmental resistance, and adhesion, and hardly diffuses into the body of the electrode material, and plating of the inner wall of the tubular or cylindrical body which is impossible in other methods is not possible. There are possible advantages.

In general, electroless plating methods for forming electrodes on PZT are performed in order of degreasing, etching, activating, and Ni plating. In this case, PZT has chemical resistance depending on the firing conditions or composition, and in each treatment process during electroless plating. The component elutes and adversely affects the plating. In particular, PZT contains Pb, which is a catalyst poison in electroless plating, which greatly affects the lifetime of the electroless plating solution, which has the largest weight on the production cost. Therefore, in order to improve plating deposition and extend the life of the bath, an appropriate plating solution is selected. And control of process variables during plating.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an electroless Ni plating method of Pb-based ceramics excellent in adhesion and the electrical contact between the base and the plating layer for forming the electrode on the PZT.

In order to achieve the above object, the present invention comprises the steps of degreasing the ceramics with CH ₃ OH or NaHCO ₄ solution; Etching the degreased ceramics with HBF ₄ solution at a concentration of 0.1-5.0%; Catalyzing the etched ceramics with a Pd-Sn solution containing 25 to 200 mL / L of HCl; Accelerating the catalyzed ceramics with a 5 to 20% H ₂ SO ₄ solution; And electroless Ni plating of the accelerated ceramics using Ni salt at a pH of 8.0 to 10.0 and a temperature of 70 to 100 ° C. to provide an electroless Ni plating method of Pb-based ceramics. .

Hereinafter, the present invention will be described in more detail.

Electroless Ni plating method of the Pb-based ceramics of the present invention, first, the degreasing process of removing the contaminants of the ceramics by immersing the ceramics, especially ceramics of complex composition such as PZT in CH ₃ OH or NaHCO ₃ solution. Conduct. When the degreasing step is carried out to remove the contaminants, the etching, which is the next step, becomes uniform, thereby improving the adhesion and making the plating uniform in the electroless plating step. The NaHCO ₃ solution is prepared by dissolving 40-50 g of NaHCO ₃ per liter of solvent in a solvent such as water.

The degreased ceramics are etched. The etching process forms a small unevenness on the surface of the ceramic body to give a hook effect to improve the adhesion of the plating and also to impart hydrophilicity to the surface of the body. Although the adhesion may be excellent as the etching is severely performed by appropriately adjusting the type and concentration of the solution used in the etching process, it is good to prevent the problem that the electrical contact characteristics may be degraded. In the present invention, an HBF ₄ solution having a concentration of 0.1 to 5.0% was used as the etching solution. When the concentration of the etching solution is less than 0.1%, ceramic-based etching hardly occurs, and when the concentration exceeds 5.0%, the etching occurs excessively. As a result, the electrical contact property is lowered, which is not preferable. The HBF ₄ solution is prepared by dissolving HBF ₄ corresponding to 0.1 to 5.0% of the weight of the solvent such as water in the solvent.

Subsequently, in order to control the speed, reduction efficiency, stability, and the like of the obtained ceramics, catalyzing and accelerating processes are sequentially performed. The catalyzing process is carried out using a Pd-Sn catalyst solution containing 25 to 200 mL / L HCl after washing the etched ceramics. In this catalysing process, Sn ²⁺ -Pd ²⁺ complex salt is adsorbed on the ceramic surface.

The Pd-Sn solution is prepared by mixing Pd salt, Sn salt and HCl. PdCl ₂ may be used as the Pd salt, and SnCl ₂ · H ₂ O may be used as the Sn salt. The Pd-Sn solution is prepared by mixing 0.1 to 0.4 g / l PdCl ₂ with 5 to 30 g / l SnCl ₂ · H ₂ O and 25 to 300 ml / l HCl. If the amount of Pd salt, Sn salt and HCl is out of the above range, the surface catalysis becomes uneven, and the plating reaction occurs very slowly or locally unevenly, which is not preferable because it is impossible to obtain a uniform plating layer which is an effect of the present invention. .

The catalyzed ceramics are washed with water, and at this time, the complex salt adsorbed on the surface of the ceramics is hydrolyzed to coexist with Sn ²⁺ , Sn ^4+, and Pd ²⁺ . Next, an acceleratoring process is performed. In the liquid seolreo rating process, the Sn ²⁺ and Sn ⁴⁺ and removed, Pd ²⁺ is by the reaction of Sn ²⁺ and Sn ⁴⁺ is a Pd ^0, Pd metal and a small amount to the ceramic surface Sn ²⁺ and Sn ^{4 +} Is left.

The axalizing process is carried out in an aqueous solution of H ₂ SO ₄ at a concentration of 5-20%. When the concentration of the H ₂ SO ₄ aqueous solution is less than 5% or more than 20%, the plating rate and the amount of the plating amount are poor, which is not preferable.

When subjected to the water washing solution seolreo decorated ceramic process, and the residual tin ions of Sn ²⁺ and Sn + ⁴ are removed, the surface of the screen by the rising kaetal Pd ceramic is obtained.

Electroless Ni plating is performed on the ceramics which have undergone such a pretreatment process using Ni salts, reducing agents, complexing agents, pH adjusting agents and buffers. At this time, the conditions of an electroless plating process shall be pH 8.0-10.0 and 70-100 degreeC. pH adjustment is controlled by using strong alkali such as NaOH or KOH as a pH regulator, when the pH is lower than 8.0 there is a problem that the plating rate is lowered, and when it is higher than 10.0, there is a problem that the surface resistance increases because the number of bonds in the plating layer increases There is this. In addition, when the plating process temperature is lower than 70 ℃, there is a problem that the plating speed drops sharply, and if the plating process temperature is higher than 100 ℃, it is difficult to handle the plating liquid.

As the Ni salt is a salt containing Ni ions, NiCl _2, NiSO ₄ or may be a hydrate of the foregoing. The reducing agent is a material that serves to reduce electrons to the surface of the catalyzed body by supplying electrons to the Ni ions, NaH ₂ PO ₂ or a hydrate thereof may be used. The pH adjuster not only adjusts the pH, but also adjusts the rate of plating, reduction efficiency stability, and the like. The complexing agent controls the amount of free metal ions in the solution to act as a factor governing the plating rate, and prevents spontaneous decomposition due to the high free metal ion concentration, and the other has an electrical interaction with hydrogen ions generated during plating. It acts as a pH buffer to prevent sudden changes in solution. Such complexing agents include citric acid (C ₆ H ₈ O ₇ ), citric acid (C ₆ H ₅ Na ₃ O ₇ ), sodium acetate (NaCH ₃ COO) or Na.EDTA (ethylene diaminetetraacetic acid) (C ₁₀ H ₁₂ N ₂ O ₈ Na ₄ .2H ₂ O) can be used. The buffer serves to buffer the change in pH that occurs as the reaction proceeds. As the buffer, a small dissociation salt or an acid such as sodium acetate, sodium citrate, boric acid or carbonic acid may be used. In addition, thiourea NaCN or MBT (mercapto benzo thiazole), which serves to stabilize the solution by inhibiting spontaneous decomposition of the plating solution, may be further used as a stabilizer. The amount of the Ni salt, the reducing agent, the complexing agent, the buffer and the pH adjusting agent is not particularly limited as long as it is appropriately adjusted.

The following presents a preferred embodiment to aid the understanding of the present invention. However, the following examples are merely provided to more easily understand the present invention, and the present invention is not limited to the following examples.

(Example 1)

PZT ceramics were immersed in CH ₃ OH for 5 minutes to carry out a pretreatment degreasing process to remove contaminants from PZT ceramics. The degreased PZT ceramics were etched for 5 minutes with 2% HBF ₄ solution to make them hydrophilic. Subsequently, the etched PZT ceramics were washed with water and then catalyzed at a temperature of about 45 ° C. for 1 minute using a solution of 0.4 g / L PdCl ₂ , 20 g / L SnCl ₂ .2H ₂ O, and 25 to 200 mL / L HCl. Was done.

Catalyzed PZT ceramics were immersed by immersing 10% H ₂ SO ₄ solution for 5 minutes. Then, aekseol by a fine wash the decorated PZT ceramics with distilled water, with 44 g / L NiCl _2, the reducing agent to the metal salt _{11 g / L NaH 2 PO 2} · H 2 O, a complexing agent and buffering agent C ₆ H ₅ O ₇ Electroless Ni plating was performed using Na ₃ .2H ₂ O, respectively. At this time, the electroless plating was performed for 1 hour by adjusting the pH to 8, the temperature to 70 ℃ using NaOH as a pH regulator. (Comparative Example 1)

NH ₄ OH was used as a pH adjuster, except that the pH was adjusted to 3.

Adhesion and surface resistance of the plated layer at room temperature were measured using PZT ceramics plated by the method of Example 1 and Comparative Example 1, and the results are shown in Table 1 below.

Example 1 Comparative Example 1 Adhesion [㎏ / ㎣] 0.084 0.035 Surface resistance [ohm / cm] 0.079 0.173

As shown in Table 1, in the case of Example 1, the adhesion was greatly improved compared to Comparative Example 1, and the surface resistance was reduced by 50% or more, thereby showing excellent plating characteristics.

The electroless Ni plating method of the present invention significantly improves the adhesion and the electrical contact between the base and the plated layer has an effect of high practicality as an electroless Ni plating method on a Pb-based ceramic matrix.

Claims (2)

Degreasing the ceramics with CH ₃ OH or NaHCO ₄ solution; Etching the degreased ceramics with HBF ₄ solution at a concentration of 0.1-5.0%; Catalyzing the etched ceramics with a Pd-Sn catalyst solution containing 25-200 mL / L of HCl; Accelerating the catalyzed ceramics with a H ₂ SO ₄ solution at a concentration of 5 to 20% to produce ceramics catalyzed by Pd; And Electroless Ni plating the surface-catalyzed ceramics using Ni salt at a pH of 8.0 to 10.0 and a temperature of 70 to 100 ° C. The electroless Ni plating method of Pb type ceramics which contains a rule. The Pb of claim 1, wherein the Pd-Sn solution comprises 0.1 to 0.4 g / l of PdCl ₂ , 5 to 30 g / l of SnCl ₂ · H ₂ O, and 25 to 300 ml / l of HCl. Electroless Ni plating method of ceramics.