JP2014019948A - Composite multilayer nickel electroplating layer and electroplating method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite multilayer nickel electroplating layer having corrosion resistance and weldability and having improved internal stress and plating efficiency, and an electroplating method therefor.SOLUTION: The composite multilayer nickel electroplating layer comprises: nickel in a first layer; nickel in a second layer; and a nickel plating layer in a surface layer, and precipitation for one time to several times can be repeated to the nickel in the first layer and the second layer. In the composite multilayer nickel electroplating layer, the internal stress direction of each layer nickel in the composite multilayer nickel electroplating is made reverse to the stress direction of the adjacent plating layer, thus the internal stress in the nickel electroplating layer is reduced, and the nickel electroplating layer in the second layer has a columnar structure, thus the stress between the nickel electroplating layers is buffered.

Description

  The present invention relates to a composite multilayer, in particular, a three-layer nickel electroplating layer and an electroplating method thereof.

  Electrolytic deposition is the most common nickel plating technique and is widely applied to prevent corrosion of metal substrates. Therefore, the nickel plating layer may be the outermost plating layer or a base layer for noble metal electroplating. When applied to the outermost layer of electroplating, the nickel plating layer has mainly interior and functional effects, and can have, for example, semi-gloss or gloss, corrosion resistance and wear resistance. In a further complicated electroplating method, when a noble metal or an alloy thereof is used as the outermost layer of electroplating, the nickel plating layer suitably bonds the substrate and the outermost layer of electroplating as an intermediate layer. In particular, the nickel plating layer may be substituted for the corrosion resistant layer when the outermost electroplating layer is partially or completely damaged.

  U.S. Pat. No. 4,767,509 discloses a method of electroplating nickel-phosphorous on a substrate using a chloride bath, and the total chlorine salt electroplating solution is more effective than the conventional sulfate bath technology. In addition, it has a high cathode efficiency, excellent conductivity, and has an advantage that only a small amount of deposition appears during the electroplating process.

  U.S. Pat. No. 6,099,624 discloses a method for electroplating nickel-phosphorus using a highly conductive electrolyte such as nickel alkyl sulfonate, which solution relates to high speed electroplating. Provided.

  However, single-layer nickel has the inevitable drawbacks of (1) degradation of electroplating bath efficiency and (2) relatively high internal stress present in the electroplating layer. In the case of the above (1), the deposition rate of electroplating decreases as the thickness of the nickel electroplating layer increases due to the deterioration of the electroplating bath efficiency. For example, in the case of an electroplating bath containing nickel sulfate, such as a Watts nickel plating bath, the cathode efficiency and plating solution conductivity are relatively low, so obtaining a suitable electroplating layer can be achieved at high voltage or long time. Is required. If phosphorus-nickel is used instead, the resulting plating layer will always have high internal stress, in addition to lower electroplating efficiency due to the low conductivity of the plating solution, thereby reducing the adhesion of the plating layer. It lacks ductility. Furthermore, the internal stress problem becomes more serious with increasing plating layer thickness. The nickel electroplating layer having such a defect easily peels, tears or cracks, and the protective function of a part or all of the electroplating layer becomes invalid. A similar damage effect is exhibited when the nickel layer is used as a base layer for noble metal electroplating, and the two electroplating layers are both damaged.

  U.S. Pat. No. 4,908,280 discloses a method for producing double-layer nickel having scratch resistance and corrosion resistance, wherein the first layer is a nickel plating layer and the second layer is a nickel-phosphorous plating layer . Since there are two layers of nickel, the scratch resistance of the plating layer can be improved with an increased thickness.

  By the way, the conventional nickel electroplating technology can provide only limited corrosion resistance, whether it is single-layer nickel or double-layer nickel, and comprehensive requirements for corrosion resistance, especially cola electrolytic test (Apple standard) ) Often fail to meet new industry standards such as The anti-cola electrolysis test is a method of an accelerated test, and measures the corrosion resistance effect after electrolysis with a cola solution to which a salt such as sodium chloride is added with few members after electroplating. The test is so severe that the gold or gold-cobalt electroplated layer is corroded without the underlying layer.

  According to the results of research on multilayer electroplating protection technology of Nd-Fe-B powder alloy by Hisamoto Xehara et al. (MATERIAL PROTECTION, Vol.31, No.6, June, 1998), chemical nickel-phosphorus plating (Ni-P) or copper nickel ( Cu-Ni) alloy plating layer has excellent airtightness to the Nd-Fe-B substrate as the underlayer. Since the potential of the plated high-sulfur nickel layer is lower than that of the semi-bright nickel as the uppermost layer and the copper-nickel (Cu-Ni) or NiP chemical-plated layer as the underlayer, the corrosion is lateral in the high-sulfur nickel layer. The Cu-Ni / Ni-P / high sulfur-Ni / semi-bright nickel system and the Ni-P / high sulfur-Ni / semi-bright nickel system are excellent in protection. Japanese Patent Documents JP7-331486A and JP8-3763A each disclose a method for producing a magnetic alloy with improved corrosion resistance. In the former, three plating layers are specifically laminated on the surface of the alloy, a caulking nickel plating film is used as a base film on the alloy surface, a copper plating layer is used as an intermediate layer, and a Ni-P alloy plating layer is used as a surface layer. The film is preferably formed by electroplating to form a plating film with good adhesion, effectively preventing pinholes and improving corrosion resistance. In the latter, a copper or nickel plating layer is formed on a magnetic base metal alloy having a specific composition using an alkaline electroless plating bath, and then an electrolytic copper plating layer or a nickel electroplating layer is used as an intermediate layer. The surface layer is a phosphorus-nickel alloy formed by Thereby, the corrosion resistance of the magnetic alloy is significantly improved. Chinese Patent Document CN101978096A relates to a corrosion-resistant conductive layer system including a Ni-P layer on a substrate, preferably a copper-based substrate, and a method of manufacturing the same. Such a conductive layer system comprises (i) a Ni layer, (ii) a Ni-P layer, and (iii) an Au layer of a substrate whose surface is electropolished.

  These existing technologies disclose various multilayer electroplating technologies, all of which realize good corrosion resistance and wear resistance of the substrate to be plated from the chemical viewpoint alone. Other than that, there is nothing related to reducing internal stress, whisker growth rate, delamination, cracks, scale risk and improving weldability.

  Among various nickel plating layers, phosphorus-nickel has the most internal stress. In the overall method, when the phosphor-nickel layer is first electroplated, the multilayer nickel plating is cracked or peeled off from the plating underlayer due to high internal stress. In order to achieve improved corrosion resistance, durability, conductivity and weldability, the issues to be preferentially solved are the reduction of high internal stresses present in the nickel electroplating layer and low electroplating efficiency.

US Patent 4,767,509 Specification US Patent US 6,099,624 US Patent 4,908,280 Specification Japanese Patent Document JP 7-331486 A Japanese Patent Document JP-A 8-3763 Chinese patent document CN101978096A

Unlike existing nickel plating technology that attempts to solve the problem only from a chemical point of view, the present invention attempts to solve the problem after analyzing it from a chemical and physical point of view. First, the present invention determines the specific electroplating order and eliminates most of the internal stress from the feature that the internal stress directions of different nickel electroplating layers are opposite. Next, in the present invention, a nickel electroplating layer (shown in FIG. 1) having a columnar structure is electroplated between two-layer nickel plating layers in which metal particle structures are densely arranged, and the relatively sparse The columnar structure is substantially perpendicular to the surface to be plated and buffers the stress generated between the nickel electroplating layers with a compact structure.

  Specifically, the present invention relates to a composite multilayer nickel electroplating layer and an electroplating method thereof. The composite multilayer nickel electroplating layer manufactured by the electroplating method includes a first nickel plating layer and a second layer. The nickel plating layer of the surface layer and the nickel plating layer of the surface layer, the three nickel plating layers, on the substrate to be plated, the internal stress direction of nickel of each layer is opposite to the stress direction of the adjacent plating layer Arranged in some electroplating order. The first nickel plating layer is caulking nickel, the second nickel plating layer is semi-bright nickel, and the surface layer is a phosphorus-nickel plating layer. Further, in the composite multilayer nickel electroplating layer of the present invention, the second nickel electroplating layer has a columnar structure in order to buffer the stress between the nickel electroplating layers. Reduction of most of the internal stress in the nickel electroplating layer by the synergistic effect that the internal stress direction between adjacent plating layers is reversed and the nickel electroplating layer of the second layer has a columnar structure Is possible. The present invention preferably employs a three-layer nickel of caulking nickel, semi-bright nickel and phosphorus-nickel. By electroplating the composite multilayer nickel or the three-layer nickel sequentially onto the metal substrate, it is possible to improve the corrosion resistance and wear resistance of the plating layer and solve the above-mentioned problems. “Corrosion resistance” in the present invention is a function representing resistance against corrosion of cola electrolysis and salt spray. When the surface layer is a noble metal, for example, an electroplating layer of gold or a gold alloy, resistance to nitric acid vapor It is also a function that represents. In the method of the present invention, the phosphor-nickel plating layer is always the uppermost layer, but the electroplating sequence of caulking nickel and semi-bright nickel is also very important. The composite multilayer nickel electroplating layer of the present invention may be an outermost plating layer or a base layer for noble metal electroplating.

  The present invention uses a specific physical shape (see FIG. 1), physical properties and chemical structure of different nickel electroplating layers to design a corresponding multi-layer nickel electroplating method to produce a unique composite multi-layer nickel electroplating. A layer is obtained. In the present invention, the order of electroplating is very important, the nickel of the first layer is deposited first, then the nickel of the second layer is deposited, the nickel of the first layer and the second layer Can repeat the deposition from one to several times. Caulking nickel is used as a first layer to fill defects such as pores on the surface of various base materials, thereby forming metal plating densely and forming an electroplating layer having a smooth surface. Semi-bright nickel plating reduces the internal stress due to the upper and lower layers of nickel as a second layer on top of the first layer and as a buffer layer between caulking nickel and caulking nickel or between caulking nickel and phosphorus-nickel It demonstrates the effect of letting In the present invention, surface nickel using phosphorus-nickel precipitates last and appears on the hard coat layer, has excellent wear resistance, and exhibits the effect of protecting the nickel in the underlayer. In multilayer nickel, especially in the three-layer nickel electroplating layer, the orientation of internal stress in each layer is different, so the first layer of caulking nickel and the surface layer of phosphorus-nickel (if it is a three-layer nickel, the third layer) The internal stress is tensile stress, but the internal stress of semi-bright nickel in the second layer is compressive stress. In such an electroplating sequence, the composite multilayer nickel electroplating layer The internal stress direction of each layer nickel is opposite to the internal stress of the adjacent nickel layer, and most of the internal stress in the nickel electroplating layer is reduced. The second nickel plating layer of the composite multilayer nickel electroplating layer according to the present invention is semi-bright nickel having a columnar structure that is substantially perpendicular to the surface of the metal substrate to be plated. The stress generated between them can be buffered. Therefore, the composite multilayer or three-layer nickel electroplating layer manufactured by the nickel electroplating method of the present invention and having a physical shape reduces high internal stress generated in the phosphor-nickel layer, that is, surface nickel. Therefore, the internal stress of the plating layer manufactured by the method of the present invention can be reduced by up to 77% compared to the general method, and the adhesion strength, peel resistance and wear resistance of the plating layer are greatly improved. be able to.

  The present invention further provides a method for electroplating a composite multilayer or three-layer nickel that is deposited on a metal substrate and includes coking nickel, semi-bright nickel, and phosphorus-nickel to enhance the corrosion resistance of the substrate. . “Corrosion resistance” in the present invention is a function representing resistance to cola electrolysis, nitric acid vapor and salt spray corrosion. According to the method of the present invention, the internal stress of the nickel plating layer can be reduced, and the generation of whiskers and the peeled area can be reduced.

  The composite multilayer nickel electroplating method of the present invention was applied to a metal substrate to suppress oxidation of the coating layer surface and improve weldability. The multilayer nickel electroplating layer produced by the above method is excellent in corrosion resistance and wear resistance, and may be applied to the outermost layer of electroplating to serve as a base layer for noble metal electroplating. The present invention provides an innovative nickel electroplating process that reduces time and improves upon a new process compared to the redundant conventional process.

  The metal substrate protected by the method of the present invention includes an iron-based material and a colored metal, such as copper, copper alloy, nickel, nickel alloy, tin, tin alloy, stainless steel, stainless steel, magnesium, magnesium alloy, Including aluminum, aluminum alloy, zinc, zinc alloy.

  In summary, the present invention relates to a composite multilayer nickel electroplating layer and an electroplating method thereof, wherein the composite multilayer electroplating layer includes a first layer nickel, a second layer nickel, and a surface layer nickel. The internal stress direction of the two layers of nickel is opposite to the stress direction of the two adjacent upper and lower nickel electroplating layers. Precipitation is repeated once to several times for the nickel of the first layer and the second layer. In the composite multilayer nickel electroplating layer of the present invention, the nickel of the second layer is semi-bright nickel having a columnar structure that is substantially perpendicular to the surface of the metal substrate to be plated. In the composite multilayer nickel electroplating layer of the present invention, the caulking nickel fills pores or defects on the surface of the substrate as the first layer, so that the formed electroplating layer is in a state of closely arranged particles. Exists. The second layer of semi-bright nickel plating layer has the effect of buffering the internal stress between the underlying layer (caulking nickel) and the adjacent or upper layer (phosphorus-nickel) nickel electroplating layer. To do. The semi-bright nickel plating layer has a columnar structure that is substantially perpendicular to the surface of the metal substrate to be plated, such a columnar structure is relatively sparse, and the stress direction is adjacent to the caulking nickel and the outermost layer. Most of the stresses in the plating layer cancel each other because the direction of stress is opposite to that of phosphorus-nickel. The uppermost layer of phosphorus-nickel appears in the hard coat layer, has excellent wear resistance, and exhibits the effect of protecting the underlying layer of nickel. Therefore, the deposition order of the multilayer nickel electroplating method of the present invention is such that the first layer of nickel is deposited first, then the second layer of nickel is deposited, and the first and second layers of nickel are deposited. On the other hand, it is possible to repeat the deposition from one to several times, and the nickel of the surface layer is finally deposited. Multi-layer, especially three-layer nickel plating, deposits in this order, maximizing the internal stress of the entire nickel electroplating layer.

Hereinafter, the electroplating method of the present invention will be sequentially described in detail.
Step 1: Surface cleaning treatment
Before operation of electroplating, the surface of the material on the cathode is coated with mineral oil, rust preventive oil, cutting water (coolant), lubricating grease, paint, fingerprints, solid particles of impurities, oxide, stratum corneum, wrinkles and rust. Remove various oils and impurities.
Step 2: Surface activation (optional)
The washed sample is placed in an acidic solution such as 5-15% dilute sulfuric acid to activate the substrate. On the other hand, the acid is also neutralized with a small amount of alkali remaining on the substrate surface in the washing step.
Step 3: Pre-nickel plating (optional)
Pre-plating is performed on the substrate that has passed the cleaning or cleaning and activation. A specific method may be referred to a pre-plating step generally used in industry, or may be performed by the method provided in the present invention. The method of the present invention is an electroplating solution of NiCl2 (250 g / L) and HCl (125 g / L). The plating bath is maintained at room temperature and applied to the substrate under electroplating conditions with an anode current density of 5 ASD. This is a method of performing electroplating for 30 seconds.
Step 4: Multi-layer nickel electroplating method
(1) Electrode: A high-purity nickel block disposed on a titanium mesh is used as an anode for nickel electroplating. Similarly, nickel strips and nickel rods are also applied as electrodes.
(2) Parameters of the electroplating method for multilayer nickel are as follows.

Multi-layer nickel electroplating method:
The sequence of multilayer nickel electroplating is (i) caulking nickel, (ii) semi-bright nickel, and (iii) phosphor-nickel.

(i) Caulking nickel
All components are mixed at a ratio shown in Table 1 to prepare a 1000 L plating solution. The plating bath temperature is maintained at 45-70 ° C. and the pH of the solution is maintained at 2.5-5.0. Electroplating is performed for 10-100 seconds under the condition of anode current density of 2.5-25ASD. The thickness of the caulking nickel plating layer is 20-80 μinch.

(ii) Semi-bright nickel
All components are mixed at a ratio shown in Table 2 to prepare a 1000 L plating solution. The temperature of the plating bath is maintained at 45-70 ° C., and the pH of the plating solution is maintained at 2.5-5.0. Electroplating is performed for 50-200 seconds under the condition of anode current density of 2.5-25ASD. The thickness of the semi-bright nickel plating layer is about 20-100 μinch.

(iii) Phosphorus-Nickel
All components are mixed at a ratio shown in Table 3 to prepare a 1000 L plating solution. The temperature of the plating bath is maintained at 45-70 ° C. and the pH of the solution is maintained at 1.0-2.5. Electroplating is performed for 5-100 seconds under the condition of anode current density of 2.5-25ASD. The thickness of the phosphor-nickel plating layer is about 5-40 μ inches.

(1) Selection of substrate
The multilayer nickel electroplating is applied to ferrous or non-ferrous metal substrates, which are copper, copper alloy, nickel, nickel alloy, tin, tin alloy, stainless steel, stainless steel, magnesium, magnesium alloy, aluminum, aluminum alloy, zinc Including, but not limited to, a zinc alloy.

The multilayer nickel electroplating layer and the electroplating method of the present invention have the following improved performance.
In certain composite multilayers of the present invention, preferably a three-layer nickel electroplating layer can be employed as an underlayer for a surface coating layer and a noble metal plating layer such as gold or gold alloy. In order to compare the corrosion resistance, durability, and other performances of various nickel plating layers or nickel and noble metal surface plating layers, comparative tests were conducted according to the following criteria.
(1) Nickel plating samples with and without a noble metal surface layer, for example, nickel plating layers with and without palladium-nickel and gold-cobalt as surface paint.
(2) A nickel-plated sample having two or three different nickel plating layers.
(3) A sample in which three layers of nickel are plated on all but the electrolytic deposition order is different.
Prior to plating the noble metal, the same noble metal is adopted for the sample having the nickel plating layer as the base layer, and at the same time, the order of the nickel plating layers is changed or two nickel plating layers instead of three layers are adopted. As a result, the composite multilayer or triple layer nickel electroplating method of the present invention was able to achieve improved corrosion resistance and durability. The composite multilayer or three-layer nickel electroplating of the present invention was used as an underlayer, and the surface layer was electroplated with a noble metal, thereby further improving the corrosion resistance and weldability of the sample. Specifically, improved performance appears from the following viewpoints.

(1) Improved cola electrolysis test
In the cola electrolytic test process, it can be seen that the sample plated with the three-layer nickel plating layer of Example 1 has excellent resistance to corrosion erosion. That is, the best results were obtained with three-layer nickel having the order of caulking nickel, semi-bright nickel and phosphorus-nickel. Two-layer nickel samples or three-layer nickel samples with a modified order (semi-bright nickel / caulking nickel / phosphorus-nickel) also have some resistance to cola electrolysis tests, but more than the three-layer nickel provided in the present invention No good effect appears.

   According to the test results, the sample having the three-layer nickel plating layer is superior in corrosion resistance to the sample having the nickel and noble metal plating layer than the sample having the two-layer nickel plating layer, regardless of the order of electrolytic deposition. Yes.

(2) Improved resistance to nitric acid vapor erosion
The test results of the samples plated with Au-Co or Pd-Ni and Au-Co after nickel plating layer are compared. As a result, it is better to plate Au—Co as the outermost layer after plating three layers of nickel than plating Au—Co after plating two layers of nickel.

(3) Improved resistance to salt spray corrosion
Compare the test results of samples plated with nickel only. Compared to double-layer nickel or modified-order triple-layer nickel, ordered triple-layer nickel such as caulking nickel / semi-bright nickel / phosphorus-nickel has better performance.

(4) greatly reduced internal stress
The present invention has the advantage of significantly reducing the internal stress of the phosphor-nickel plating layer. From the measurement, the internal stress of the plating layer manufactured by the method of the present invention is reduced by up to 77% from the general method, and the reduction of the internal stress prevents peeling and cracking, and greatly improves the adhesion strength of the plating layer. Improved wear resistance. Moreover, the generation of whiskers in the plating layer can be suppressed by reducing the internal stress, and the length of the whiskers is from several μm to several mm, which causes a short circuit.

(5) Improved weldability
The test results of a sample plated only with nickel, or a sample with a nickel plated layer as a base layer and a noble metal as a surface layer are compared. A sample plated with three-layer nickel is superior to a sample plated with two-layer nickel with respect to a sample plated with nickel alone, regardless of the order of electroplating. No significant difference appears for the nickel-noble metal plating layer sample.

  The electroplating method of the multilayer nickel of the present invention has a remarkable effect, and the obtained nickel plating layer is employed as an underlayer before noble metal electroplating, in addition to being used alone as the outermost plating layer. Reduce and exert a good economic effect. More substrates provide improved corrosion resistance, including resistance to corrosion by cola electrolysis, nitric acid vapor and salt spray. By the method of the present invention, the internal stress of the plating layer is reduced, and the possibility of cracking, peeling or cracking is minimized. Furthermore, the present invention provides an excellent method of reducing the time and cost by providing the substrate with excellent corrosion resistance and durability while reducing the overall time of the electroplating process. Moreover, the degree of oxidation of the surface to be plated is suppressed, and improved conductivity and weldability are obtained.

FIG. 1 is a photograph of an electron microscope (SEM) for a sample of a three-layer nickel plating layer in Example 1 of the present invention. Here, 1: caulking nickel of the first layer, 2: semi-bright nickel of the second layer, 3: phosphorus-nickel of the surface layer, 4: copper metal substrate, 5: filler.

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

(Trilayer nickel according to the sequence of the present invention: caulking nickel → semi-bright nickel → phosphorus-nickel)
The copper piece is connected to the cathode and immersed in a degreasing bath. Set the voltage to 5-10V and degrease for about 2 minutes. Then, after washing with deionized water, it is immersed and neutralized and activated with 10% sulfuric acid. Wash again with deionized water. Components of nickel sulfamate 100 g / L, nickel chloride 30 g / L, boric acid 40 g / L, caulking agent NHL56LE (commercially available, RamChem) 10 mL / L, brightener NHL56BR (commercially available, RamChem) 6 mL / L The sample is immersed in the plating solution containing it and electroplated on the caulking nickel. The pH of the electrolytic bath is about 3.8. Electroplating is performed at a current density of 15 ASD and a temperature of 60 ° C. After 50 seconds of electroplating, a 40-60 μinch caulking nickel layer is obtained.
Then, the sample was washed with deionized water, nickel sulfamate 80g / L, nickel chloride 13g / L, boric acid 40g / L, wetting agent WA31 (commercially available from RamChem) 10mL / L, brightener BR311 (commercially available, RamChem product) Electroplating semi-bright nickel by immersing the sample in a second electroplating solution containing 2mL / L of components. After electroplating for 90 seconds under 8 ASD conditions, 40-60 μinch semi-bright nickel is obtained. The electroplating bath employed has a pH of 3.8 and maintains the temperature at 58 ° C.

  The next step is to electroplate phosphorous-nickel as the outermost layer. Wash sample with deionized water, nickel sulfamate 100g / L, nickel chloride 15g / L, boric acid 40g / L, oxidizing agent RamTech Nicka 1225 R2 (commercially available from RamChem) 30mL / L, brightener RamTech Nicka 1225 Immerse the sample in a third electroplating solution containing components of BR (commercially available, RamChem) 11mL / L and phosphorus supplement RamTech Nicka 1225 SA (commercially available, product of RamChem) 15mL / L. Thus, after electroplating for 16 seconds, 15-30 μin phosphorus-nickel is obtained. Maintain the electroplating bath temperature at 60 ° C and PH at 1.5.

  The three-layer nickel electroplating sample obtained in this example was analyzed with an electron microscope (SEM), and FIG. 1 is a cross-sectional view thereof. 1 is the first layer of caulking nickel in the sample of the three-layer nickel electroplating, 3 is the surface layer of phosphor-nickel, and the cross-sectional view shows that the middle two, that is, the second layer of semi-bright nickel is relative It can be seen that it has a columnar structure which is sparse and substantially perpendicular to the surface of the metal substrate to be plated.

Comparative Example 1 (double layer nickel: semi-bright nickel → phosphorus-nickel):
Based on the procedure described in Example 1, 40-60 inch thick semi-bright nickel is electroplated on the copper strip, followed by 15-30 μinch thick phosphor-nickel.

Comparative Example 2 (double layer nickel: caulking nickel → phosphorus-nickel):
Based on the procedure described in Example 1, 40-60 inch thick caulking nickel is electroplated on the copper strip, followed by 15-30 μinch thick phosphor-nickel.

Comparative Example 3 (Trilayer nickel with changed order: semi-bright nickel → caulking nickel → phosphorus-nickel):
Based on the procedure described in Example 1, 40-80 μinch thick semi-bright nickel is electroplated on the copper strip, and then 40-60 μinch thick caulking nickel is electroplated on the substrate. Then, 15-30 μin thick phosphor-nickel is electroplated.

Example 2 (Three-layer nickel-noble metal electroplating according to the sequence of the present invention: caulking nickel → semi-bright nickel → phosphorus-nickel → palladium-nickel → gold cobalt):
Based on the procedure described in Example 1, three layers of nickel are electroplated on the copper piece. Thereafter, Pd—Ni electroplating is performed. Then, Au—Co is electroplated to obtain a 4 to 6 μ-inch thick gold-cobalt layer, which further improves the corrosion resistance and weldability of the sample.

Comparative Example 4 (double-layer nickel-noble metal electroplating: semi-bright nickel->phosphorus-nickel->Pd-Ni-> Au-Co):
Based on the procedure described in Example 1, 120-140 μinch thick luster nickel and 30 μinch phosphorous-nickel were electrically deposited on a copper strip, followed by 25-30 μinch thick Pd-Ni. Plating. Finally, 4 to 6 μ-inch Au—Co is electroplated.

  In order to verify the effect of the electroplating method of the composite multilayer nickel of the present invention, the sample is subjected to an anti-cola electrolysis test, a nitric acid vapor test, a salt spray test and an internal stress test. This will be described in detail below.

Cola electrolysis test:
All samples prepared according to Examples 1 and 2 and Comparative Examples 1 to 4 are subjected to a cola electrolysis test. The general process of the anti-cola electrolysis test is as follows. The cola test bath solution contains 100% cola mixed with 5% NaCl. Stainless steel is used as the cathode. A sample that has undergone standard washing and degreasing processes at room temperature is electrolyzed in a mixed solution of cola for 10 minutes, and the voltage is set to 5V. Next, the sample is placed in an ultrasonic solution, washed with deionized water, dried, and then imaged on the sample with a 10x microscope to estimate the ratio of corrosion area to total area. Judgment was made based on the following criteria. That is, when the ratio between the corroded area and the total area is less than 10%, “excellent”, when 10-30%, “pass”, and when greater than 30%, “fail”.

  The result is Comparative Example 4> Example 2> Example 1> Comparative Example 3> Comparative Example 1≈Comparative Example 2.

Nitric acid vapor test:
All samples produced according to Examples 1 and 2 and Comparative Examples 1 to 4 are subjected to a nitric acid vapor experiment according to American Test Materials Association standard ASTM B735-2000 to compare different nickel based noble metal layers. The sample after the operation was observed with a 10 × microscope, and the number of corrosion points having a diameter of 0.5 mm or more was recorded under the microscope, and the evaluation was judged according to the following criteria. That is, when the number of corrosion points is 5 or less, “pass”, and when the number of corrosion points is greater than 5, “fail”.
As a result, Example 2> Comparative Example 4 is obtained.
Explanation: All the samples manufactured according to Example 1 and Comparative Examples 1 to 3 fail the nitric acid vapor test, and only the material plated with the noble metal passes the nitric acid vapor test. The nitric acid test compares the resistance to nitric acid in different nickel-based noble metal layers. As a result, it is preferable that the three-layer nickel according to the sequence of Example 1 is used as the precious metal underlayer.

Salt spray test:
The samples produced according to Example 1 and Comparative Examples 1 to 3 are subjected to a salt spray test according to American Society for Testing and Materials standard ASTM B799. The results are shown in the table below.

  As shown in the test results shown in Table 4, after passing the salt spray test for 24 hours, from the sample plated with double layer nickel and the sample of triple layer nickel plated in a changed order, On the sample surface of the three-layer nickel plated according to the sequence (caulking nickel / semi-bright nickel / phosphorus-nickel), there is minimal discoloration without corrosion.

Internal stress test:
With a plating layer stress analyzer (manufactured by Specialty Testing & Development Co.), multilayer nickel electroplating is electroplated onto a specific strip-shaped test piece manufactured by the company, and then the internal stress is measured. The following samples were measured. All test samples were plated with approximately the same thickness of nickel.
(1) Caulking nickel (15 ASD, 150 sec)
(2) Semi-bright nickel (8 ASD, 180 sec)
(3) Phosphorus-Nickel (15 ASD, 300 sec)
(4) Caulking nickel (15 ASD, 75 sec) → Phosphorus-nickel (10 ASD, 60 sec)
(5) Caulking nickel (15 ASD, 75 sec) → Semi-bright nickel (8 ASD, 60 sec) → Phosphorus-nickel (10 ASD, 60 sec)
(6) Semi-bright nickel (8 ASD, 90 sec) → Caulking nickel (15 ASD, 15 sec) → Semi-bright nickel (8 ASD, 90 sec) Phosphorus-Nickel (10 ASD, 30 sec)
(7) Caulking nickel (15 ASD, 15 sec) → Semi-bright nickel (8 ASD, 90 sec) → Caulking nickel (15 ASD, 15 sec) → Semi-bright nickel (8 ASD, 60 sec) → Phosphorus-Nickel (10 ASD, 30 sec) )

Plating bath conditions: a double anode, the distance between the anode and the test sample was 3 inches, and the surface area of the test sample was 0.0774 dm ² .

a formula
Nickel plating layer thickness (inch): T = [(weight after plating-original weight) / specific metal density] x 0.0509
Internal stress (pound / square inch) = [distance from anode to cathode / (3 × thickness)] × test constant
Here, the test constant is the normal number of test pieces of the specific strip-shaped test piece, which is provided to the manufacturer.

  Other than that, the terminal bias direction is the direction of stress in the plating layer. If the terminal in the test area can project outward to the electroplating side (the electroplating surface is outside and the corrosion-resistant surface is inside), the stress attribute of the plating layer is tensile stress. If the terminal in the test area can be extended inward to the electroplating side (the electroplating surface is outside and the corrosion-resistant surface is inside), the stress attribute of the plating layer is compressive stress.

From the above results, the following can be clearly seen.
(1) Semi-bright nickel has compressive internal stress, while caulking nickel and phosphorus-nickel have tensile internal stress.
(2) When plating semi-bright nickel between caulking nickel and phosphorus-nickel in different directions of internal stress, for example, comparing sample D and sample E, the internal stress is 11124.67psi (sample D) From 256.997 psi (sample E), the internal stress figure is reduced by 77%.

Weldability test:
A weldability test is performed on all samples manufactured according to Examples 1 and 2 and Comparative Examples 1 to 4. Weldability was evaluated by a wet equilibrium test apparatus described in the printed circuit board weldability test standard IPC / EIAJ-STD-003A of the American Electronic Circuit Association.

Results: Example 2≈Comparative Example 4> Example 1≈Comparative Example 3> Comparative Example 1≈Comparative Example 2
Description: The nickel electroplated layer in the order of the present invention is excellent in weldability, and further improves the weldability by the surface layer plated with the noble metal.

Claims (20)

A composite multilayer nickel electroplating layer comprising nickel of the first layer, nickel of the second layer, and nickel of the surface layer,
In the composite multilayer nickel electroplating layer, the internal stress direction of nickel of each layer in the composite multilayer nickel electroplating layer is opposite to the stress direction of the adjacent plating layer on the metal substrate to be plated. A composite multilayer nickel electroplating layer, characterized by being arranged in an electroplating sequence so as to reduce internal stress.   2. The composite multilayer nickel electroplating layer according to claim 1, wherein the internal stress of nickel in the first layer is tensile stress, and the internal stress of nickel in the second layer is compressive stress.   2. The composite multilayer nickel electroplating layer according to claim 1, wherein the nickel of the surface layer is phosphorus-nickel, and the internal stress is a tensile stress.   The deposition order of the composite multilayer nickel electroplating layer is such that after the nickel of the first layer is deposited first, the nickel of the second layer is deposited, and the nickel of the first layer and the second layer is several times from one time. 2. The composite multilayer nickel electroplating layer according to claim 1, wherein the surface layer nickel is finally deposited by repeating the deposition up to 1 time.   The composite multilayer nickel electroplating layer according to claim 1, wherein the nickel of the first layer is caulking nickel.   6. The composite multilayer nickel electroplating layer according to claim 5, wherein the first layer of the caulking nickel electroplating layer has particles arranged densely and has a smooth surface.   The composite multilayer nickel electroplating layer according to claim 1, wherein the second nickel plating layer is semi-bright nickel.   The composite multilayer nickel electroplating layer according to claim 1, wherein the metal substrate to be plated is an iron-based material or a colored metal substrate.   The metal substrate to be plated is copper, copper alloy, nickel, nickel alloy, tin, tin alloy, stainless steel, stainless iron, magnesium, magnesium alloy, aluminum, aluminum alloy, zinc or zinc alloy. The composite multilayer nickel electroplating layer according to claim 8.   10. The composite multilayer according to claim 1, wherein the nickel plating layer of the second layer is semi-bright nickel having a columnar structure that is substantially perpendicular to the surface of the metal base material to be plated. Nickel electroplating layer.   The composite multilayer nickel electroplating layer is a three-layer nickel electroplating layer comprising a first layer of nickel, a second layer of nickel, and a surface layer of nickel. Multi-layer nickel electroplating layer.   12. The Pd—Ni electroplating layer and the Au—Co electroplating layer having a thickness of 4 to 6 μ inch are further provided on the three nickel electroplating layers. A composite multilayer nickel electroplating layer as described in 1.   The composite multilayer nickel electroplating layer according to claim 11, wherein an internal stress of the three nickel electroplating layers is reduced by 77%.   A surface plating layer of a metal substrate, wherein the composite multilayer nickel electroplating layer according to any one of claims 1 to 13 is used.   An underlayer before a noble metal plating layer or a metal alloy plating layer, wherein the composite multilayer nickel electroplating layer according to any one of claims 1 to 11 and claim 13 is used. Step 1 for cleaning the surface of the substrate;
Step 2 optionally surface activating the substrate after washing with an acid solution;
Optionally step 3 of pre-plating nickel on the substrate;
Step 4 of sequentially electroplating a multilayer nickel plating layer containing nickel of the first layer, nickel of the second layer, and nickel of the surface layer on the surface of the substrate to be plated;
A method for electroplating composite multilayer nickel comprising:
The composite multilayer nickel electroplating method, wherein the nickel internal stress direction of each layer in the obtained composite multilayer nickel electroplating layer is opposite to the stress direction of the adjacent plating layer.   The deposition order of the composite multilayer nickel plating layer is such that after the nickel of the first layer is first deposited, the semi-bright nickel of the second layer is deposited, and the nickel of the first layer and the second layer is once. 17. The method for electroplating a composite multilayer nickel according to claim 16, wherein the deposition is repeated up to several times, and finally nickel on the surface layer is deposited.   The method of claim 16, wherein the first layer is coking nickel, the second layer nickel is semi-bright nickel, or the surface layer is phosphorus-nickel.   The method of claim 16, wherein the first layer nickel and the second layer nickel are deposited once.   The composite multilayer nickel electroplating according to any one of claims 16 to 19, wherein the second layer is semi-bright nickel having a columnar structure substantially perpendicular to the surface of the metal substrate to be plated. Method.