WO2002004714A1 - Electrolytic copper-plated r-t-b magnet and plating method thereof - Google Patents
Electrolytic copper-plated r-t-b magnet and plating method thereof Download PDFInfo
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- WO2002004714A1 WO2002004714A1 PCT/JP2001/005798 JP0105798W WO0204714A1 WO 2002004714 A1 WO2002004714 A1 WO 2002004714A1 JP 0105798 W JP0105798 W JP 0105798W WO 0204714 A1 WO0204714 A1 WO 0204714A1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
- H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
- H01F41/0253—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets
- H01F41/026—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing permanent magnets protecting methods against environmental influences, e.g. oxygen, by surface treatment
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/38—Electroplating: Baths therefor from solutions of copper
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D7/00—Electroplating characterised by the article coated
- C25D7/001—Magnets
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- Y10S428/922—Static electricity metal bleed-off metallic stock
- Y10S428/9335—Product by special process
- Y10S428/934—Electrical process
- Y10S428/935—Electroplating
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Definitions
- the present invention provides an RTB magnet having a substantially uniform film thickness, having no pinholes, and having an electrolytic copper-plated film having excellent scratch resistance and containing no cyanide!
- the present invention relates to a method of forming such an electrolytic copper plating film on an RTB-based magnet using the same. Background art
- R-Fe-B-based magnets whose main phase is Fei 4 B intermetallic compound (R is at least one rare earth element including Y) is generally inferior in oxidation resistance and is usually coated by plating. You. Nickel, copper, etc. are generally used as the plating metal. However, since the nickel plating solution is acidic, the magnet itself will be eroded if it comes into direct contact with the R-Fe-B magnet. Therefore, a nickel plating film is formed after forming a copper plating film as an underlayer on the surface of the R-Fe-B magnet.
- Copper cyanide has been conventionally used for copper plating from the viewpoints of adhesion to magnet materials and prevention of pinholes (Japanese Patent Application Laid-Open No. 60-54406).
- copper cyanide is highly toxic, so it is necessary to pay close attention to ensuring production safety, plating solution management and wastewater treatment. Given the recent trend to avoid the use of environmentally harmful substances, a copper plating method that does not use copper cyanide is desired.
- Known plating solutions for electrolytic copper for R-Fe-B magnets include plating solutions of copper phosphate, copper sulfate, and copper borofluoride, in addition to the plating solution of copper cyanide.
- the metal elements in the R-Fe-B magnet elute or displace, and the resulting electrolytic copper plating It was found that not only did the coated film not show good adhesion to the R-Fe-B magnet, but the magnet itself did not show high thermal demagnetization resistance. .
- Electroless plating has also been performed on R-Fe-B magnets.
- Electroless plating As a method, JP-A-8-3763 discloses that an R-Fe-B magnet has an electroless copper plating film as a first layer, an electrolytic copper plating film as a second layer, and an electrolytic nickel-phosphorous film as a third layer. A method for forming a plating film is proposed. However, in this method, since the first layer is an electroless copper plating film, not only is the adhesion to the R-Fe-B magnet inferior, but the electroless plating solution is more unstable than the electrolytic plating solution. There is a problem that self-decomposition is easy.
- JP-A-5-9776 discloses a chelating agent of 30 to 60 g / liter (hereinafter referred to as g / L). And 5 to 30 g / L of copper sulfate or chelated copper, 50 to 500 ppm of a surfactant, and 0.5 to 5 cm 3 / liter of a pH buffer, with a pH of 8 to 10 It proposes a method of plating electrolytic copper at a current density of 0.2 to 2.0 A / dm 2 using a liquid.
- the R-Fe-B magnet is gradually oxidized and loses the desired magnetic properties. Further, even if the adhesion strength to the R-Fe-B magnet is poor, a problem of peeling of the copper plating film occurs, which causes oxidation of the R-Fe-B magnet. Also, when the Vickers hardness of the copper-plated film falls below a specified value, the surface of the copper-plated film has a small dent (about 50 to 500 ⁇ ) due to the collision of R-Fe-B magnets with copper plating. Dents are formed, resulting in poor appearance and poor corrosion resistance. Purpose of the invention
- an object of the present invention is to provide an electrolytic copper plating film having a substantially uniform film thickness, having no pinholes, and having excellent scratch resistance on an RTB-based magnet using a highly toxic cyanide-free electrolytic copper plating solution.
- An object of the present invention is to provide a method for forming the same, and an RTB-based magnet having such an electrolytic copper plating film.
- the method of the present invention for electrolytically plating an RTB-based magnet (R is at least one of the rare earth elements including Y, and ⁇ is Fe or Fe and Co) by 20 to: 50 g / L sulfuric acid It is characterized by using an electrolytic copper plating solution that contains copper and a chelating agent of 30 to 250 g / L, does not contain a reducing agent for copper ions, and has a pH of 10.5 to 13.5.
- EDTA ethylenediaminetetraacetic acid
- the X-ray diffraction peak intensities from the (200) plane are 1 (200) and (111) planes. Ratio of X-ray diffraction peak intensity to 1 (111) from [1 (200) / 1 (111)] force SO.:! 0.40.45.
- the RTB magnet is preferably a main phase an R 2 T M B intermetallic compound, has good corrosion resistance and high thermal demagnetization resistance.
- the number of pinholes in the electrolytic copper plating film measured by the Feixel xyl test method (JIS H 8617) was 0 / cm 2 .
- the electrolytic copper plating film has a Vickers hardness of 260 to 350 and is highly scratch-resistant. More preferred Vickers hardness is 275-350.
- Electrolytic copper plating film as the first layer Ni, Ni-Cu alloy, M-Sn alloy, Ni-Zn alloy, Sn-Pb alloy, Sn, Pb, Zn, Zn-Fe It is preferable to have a second layer made of at least one type of plating film selected from the group consisting of a base alloy, a Zn-Sn based alloy, Co, Cd, Au, Pd and Ag.
- the plating film constituting the second layer is preferably an electrolytic or electroless nickel plating film.
- a chemical conversion film such as chromate on the second layer of the plating film. If the surface of the chemical conversion film is alkali-treated with an aqueous NaOH solution or the like, the adhesiveness of the surface of the chemical conversion film is improved. is there.
- the plating film comprises, in order from the magnet side, an electrolytic copper plating film and an electrolytic or electroless nickel plating film.
- the ratio of the X-ray diffraction peak intensity 1 (200) from the (200) plane to the X-ray diffraction peak intensity 1 (111) from the (111) plane [1 (200) / 1 (111)] is 0.1 to 0.45
- the electrolytic copper plating film contains 20 to: L50 g / L of copper sulfate and 30 to 250 g / L of a chelating agent, and the reduction of copper ions. It is characterized by being formed by an electrolytic copper plating method using an electrolytic copper plating solution whose pH is adjusted to 10.5 to 13.5 without containing a base agent.
- the electrolytic copper plating method of the present invention is particularly suitable for forming a thin or small-sized RTB-based magnet having no pinholes on its surface and having a substantially uniform electrolytic copper plating film having excellent scratch resistance.
- the RTB magnet having such an electrolytic copper plating film is suitable for a rotary machine or an actuator.
- FIG. 1 is a flowchart showing steps of an electrolytic copper plating method according to one embodiment of the present invention.
- FIG. 2 (a) is a schematic diagram for explaining a sound appearance of the Cu / Ni-plated R-T-B-based magnet of Example 11.
- Fig. 2 (b) is a schematic diagram for explaining the appearance of the Cu / Ni plated R-T-B based magnet of Comparative Example 9 having a dent,
- FIG. 3 is a graph showing the X-ray diffraction pattern of the RTB magnet of Example 1
- FIG. 4 is a graph showing the X-ray diffraction pattern of the RTB magnet of Comparative Example 4
- FIG. It is a graph showing the relationship between the current density in the electrolytic copper plating process and the adhesion of the plating film to the RTB magnet.
- FIG. 6 is a graph showing the relationship between the electrolytic copper plating time in Example 11, the thermal demagnetization rate of the plated R-T-B magnet, and the number of pinholes in the plating film.
- Fig. 7 (a) is a scanning electron micrograph showing the cross-sectional structure of the center part on the outer diameter side of the Cu / Ni-plated R-T-B ring magnet in Example 11.
- FIG. 7 (b) is a scanning electron micrograph showing the cross-sectional structure of the center part on the inner diameter side of the Cu / Ni plated R-T-B ring magnet in Example 11.
- the Cu-plated RTB magnets of this effort are It is obtained by immersing an RTB-based magnet in an electrolytic copper plating bath with a strong force to form an electrolytic copper plating film by an electrolytic copper plating method using a rack.
- the Cu / Ni-plated RTB magnet according to the preferred embodiment of the present invention is formed by dipping the RTB magnet in an alkaline electrolytic copper plating bath to form an electrolytic copper plating film (first layer). Obtained by forming an electroless nickel plating film (surface layer: second layer).
- the role of the electrolytic copper plating film is (l) good adhesion to the RTB-based magnetite substrate, (2) suppression of deterioration of magnetic properties, and (3) good contact with the RTB-based magnet. Possibility (uniformity of plating film).
- the electrolytic copper plating method is generally superior to the electroless copper plating method.However, when the RTB magnet is immersed in a conventional acidic electrolytic copper plating solution, the RTB The metal component in the system magnet may elute into the plating solution, causing a replacement reaction with the metal ion in the plating solution, resulting in a decrease in the adhesion of the finally obtained plating film of the RTB-based magnet. To prevent this, the electrolytic plating solution needs to be alkaline within a predetermined pH range.
- the adhesion decreases, so that the softer electrolytic copper plating is advantageous to increase the adhesion.
- dents may be formed on the surface of the electrolytic copper plating film due to mutual collision of the workpieces during the electrolytic copper plating, resulting in poor appearance and the possibility of becoming a starting point of a pinhole. Therefore, it is extremely important in practical use to give a predetermined Vickers hardness to the electrolytic copper plating film.
- the deterioration of the magnetic properties of (2) can be suppressed unless the metal components of the RTB magnet elute in the electrolytic copper plating solution. It is good to make the solution alkaline.
- the electroless copper plating method was more advantageous than the electrolytic copper plating method, but as a result of intensive studies, a complex type alkaline electrolytic copper plating solution was used. As a result, it was found that an electrolytic copper plating film having a throwing power equal to or higher than that of the electroless copper plating film was obtained.
- Copper sulfate concentration in such electrolytic copper plating solution The degree is 20 to: L50 g / L, preferably 40 to 100 g / L.
- the concentration of copper sulfate is lower than 20 g / L, the plating speed is extremely low, and it takes much time to obtain an electrolytic copper plating film having a desired film thickness. Further, even if the concentration of copper sulfate exceeds 150 g / L, there is no merit associated with it, and only excess copper sulfate is wasted.
- the concentration of EDTA is 30-250 g / L, preferably 50-200 g / L. If the EDTA concentration is lower than 30 g / L, copper slime is gradually generated after bathing, which not only impairs the stability of the electrolytic copper plating solution, but also adheres to the substrate by attaching copper slime to the RTB magnet. This leads to a decrease in sex. Also, increasing the EDTA concentration above 250 g / L has no associated benefit and only wastes excess EDTA.
- chelating agents other than EDTA diethylenetriaminepentaacetic acid (DTPA), N-hydroxyethylenediaminetriacetic acid (HEDTA), ⁇ , ⁇ , ⁇ , ⁇ -tetrakis- (2-hydroxypropynole) -ethylenediamine (THPED ) Or an aminocarboxylic acid derivative.
- DTPA diethylenetriaminepentaacetic acid
- HEDTA N-hydroxyethylenediaminetriacetic acid
- THPED ⁇ -tetrakis- (2-hydroxypropynole) -ethylenediamine
- the electrolytic copper plating bath used in the electrolytic copper plating method of the present invention does not contain a reducing agent for copper ions such as formaldehyde.
- a copper ion reducing agent is contained, an electrolytic copper plating film having many pin holes can be obtained.
- the pH of the electrolytic plating solution is from 10.5 to 13.5, preferably from 11.0 to 13.0, and more preferably from 11.0 to 12.5.
- the pH is less than 10.5, a rough electrolytic copper plating film is formed, and when the pH is more than 13.5, a tendency for hydroxide to form on the surface of the electrolytic copper plating film becomes remarkable. Adhesion with the plating film decreases.
- the current density in the electrolytic copper plated is preferably 0.1 ⁇ 1.5 A / dm 2, 0.2 ⁇ 1.0A / dm 2 is more preferable. If the current density is less than 0.1 A / dm 2 , the copper plating speed becomes remarkably slow, and it takes a lot of plating time to obtain an electrolytic copper plating film of a predetermined film thickness. This leads to poor adhesion. On the other hand, plated turbocharger Ke is generated by reduction of the current density force Sl.5 A / dm 2 larger than the current efficiency, throwing decreases.
- the temperature of the electrolytic copper plating bath is preferably from 10 to 70 ° C, more preferably from 25 to 60 ° C. If the bath temperature is lower than 10 ° C, a rough copper plating film is obtained, and the adhesion to the RTB-based magnet substrate is reduced. In addition, crystals are precipitated due to the decrease in the solubility of EDTA, which causes a change in the composition of the electrolytic copper plating bath. On the other hand, if the bath temperature is higher than 70 ° C, carbonate formation accelerates. As a result, the pH drop becomes remarkable, the evaporation of the electrolytic copper plating liquid becomes severe, and the control of the plating liquid becomes difficult.
- the electrolytic copper plating film formed on the R-T-B magnet usually has a gloss, but if it is desired to further increase the gloss, it is preferable to add a predetermined amount of brightener. When it is desired to increase the smoothness, it is preferable to appropriately add a predetermined amount of a leveling agent.
- the average thickness of the electrolytic copper plating film formed on the R-T-B-based magnet is preferably 0.5 to 20 ⁇ m, more preferably 2 to 10 ⁇ . If the average film thickness is less than 0.5 ⁇ , practically no covering effect can be obtained. On the other hand, even if it exceeds 20 / zm, not only the coating effect is saturated, but also the magnetic gap when incorporated in a magnetic circuit becomes excessive, and there is a possibility that desired magnetic properties cannot be exhibited.
- R-T-B magnets are degreased with a suitable degreasing agent before electrolytic copper plating, and then washed with water. After that, the R-T-B magnet is immersed in a dilute nitric acid bath, and then washed with water to clean the surface of the R-T-B magnet.
- a suitable degreasing agent for acid treatment, at least one selected from the group consisting of dilute sulfuric acid or a salt thereof, dilute hydrochloric acid or a salt thereof, and dilute nitric acid or a salt thereof may be used instead of the diluted nitric acid solution.
- the acid concentration is preferably from 0.1 to 5% by weight, more preferably from 0.5 to 3% by weight, based on the acid treatment bath.
- the surface of the R-T-B magnet is required to be hard. Normally, a soft electrolytic copper-plated film is not suitable for the surface layer, and therefore, it is preferable to form a high-hardness nickel plating film on the electrolytic copper-plated film. For forming a nickel plating film having high hardness, a known electrolytic or electroless nickel plating method can be applied.
- the electrolytic nickel plating solution suitable for the present invention a solution containing a predetermined amount of nickel sulfate, nickel chloride and phosphoric acid is preferred.
- the concentration of nickel sulfate is preferably 150 to 350 g / L, more preferably 200 to 300 g / L.
- the concentration of nickel sulfate is less than 150 g / L, the plating speed of the electrolytic nickel is extremely reduced, and it is difficult to obtain a desired film thickness. It takes a lot of man-hours. If the concentration of nickel sulphate is higher than 350 g / l, there is no advantage and only excess nickel sulphate is wasted.
- the concentration of nickel chloride is preferably from 20 to 150 g / L, and more preferably from 30 to: LOO g / L. If the concentration of nickel is less than 20 g / L, dissolution of the anode is hindered, the plating voltage increases, and the current efficiency decreases. If the concentration of nickel chloride is more than 150 g / L, the internal stress of the electrolytic nickel plating film will increase, and the adhesion of the plating film will decrease.
- the concentration of boric acid is preferably from 10 to 70 g / L, more preferably from 25 to 50 g / L.
- concentration of boric acid is less than 10 g / L, the pH buffering action is weakened, the pH of the electrolytic nickel plating solution fluctuates greatly, and the management of the plating solution becomes complicated.
- concentration of boric acid above 70 g / L has no merit and only wastes excess boric acid.
- the pH of the electrolytic nickel plating solution is preferably from 2.5 to 5, more preferably from 3.5 to 4.5. If the pH is lower than 2.5, the coating becomes brittle and electrolytic Ni-plated. If the pH is higher than 5, precipitation of nickel hydroxide occurs, and the stability of the electrolytic nickel plating solution is impaired.
- the temperature of the electrolytic nickel plating bath is preferably from 35 to 60 ° C, more preferably from 40 to 55 ° C. When the bath temperature is lower than 35 ° C or higher than 60 ° C, a coarse nickel plating film is formed.
- the current density is preferably from 0.1 to 1.5 A / dm 2, and more preferably from 0.2 to LO A / dm 2 . If the current density is less than 0.1 A / dm 2, the plating speed of the electrolytic nickel becomes slow, and not only takes a large amount of plating time to obtain a predetermined film thickness, but also causes poor adhesion due to poor deposition. If the current density is larger than 1.5 A / dm 2 , burnt spots occur and the throwing power decreases.
- the average thickness of the nickel plating formed on the electrolytic plating film of the RTB magnet be 0.5 to 20 ⁇ m. More preferably, it is 10 m. If the average film thickness is less than 0.5 ⁇ , the coating effect of the nickel plating film is practically not obtained, and if it exceeds 20 ⁇ m, the coating effect is saturated. [2] electrolytic copper plating film
- the electrolytic copper plating film formed on the RTB magnet was analyzed by X-ray diffraction (CuKal line), pinhole, Vickers hardness and appearance, and the X-ray diffraction peak intensity from the (200) plane was 1 (200)
- the ratio of [1 (200) / 1 (111)] to the X-ray diffraction peak intensity 1 (111) from the (111) plane is within the range of 0.1 to 0.45, there is no pinhole and no dent. It did not occur.
- 0.20-0.35 is more preferable. It is difficult to industrially produce electrolytic copper plating films with 1 (200) / 1 (111) less than 0.1.
- Thin wall with minimum thickness of 3 mm or less:-Applying the electrolytic copper plating method of the present invention to a TB-based magnet can provide a thin RTB-based magnet with good corrosion resistance and thermal demagnetization resistance .
- the irreversible demagnetization rate is preferably 1% or less, particularly preferably 0%.
- the composition of the RTB magnet to which the electrolytic copper plating method of the present invention is applied is as follows: R: 27 to 34% by weight, B: 0.5 to 2%, with the total of the main components (R, B and! 1 ) being 100% by weight. %, The balance being T, and preferably having a structure mainly composed of R 2 Ti 4 B intermetallic compound.
- R Nd + Dy preferred to use Pr s Dy + Pr, or Nd + Dy + Pr.
- the content of R is preferably 27 to 34% by weight.
- R is less than 27% by weight, the intrinsic coercive force iHc is extremely low, and when R exceeds 34% by weight, the residual magnetic flux density Br is significantly reduced.
- the content of B is preferably 0.5 to 2% by weight. If B is less than 0.5% by weight, practically usable iHc cannot be obtained, and if it exceeds 2% by weight, ⁇ 'is extremely low. The more preferable content of ⁇ is 0.8 to 1.5% by weight. In order to have good magnetic properties, it is preferable to contain at least one element selected from the group consisting of Nb, Al, Co, Ga and Cu.
- Nb When Nb is contained in an amount of 0.1 to 2% by weight, borides of Nb are generated during the sintering process, abnormal grain growth of main phase grains is suppressed, and the coercive force of the R-T-B magnet is improved. If the Nb content is less than 0.1% by weight, the effect of improving the coercive force is insufficient, and if it exceeds 2% by weight, the amount of Nb boride generated is excessive, and Br is extremely low.
- the content of Co is preferably 0.3 to 5% by weight. If the Co content is less than 0.3% by weight,
- the effect of improving the curability and corrosion resistance of the R-T-B based magnet is insufficient, and when it exceeds 5% by weight, the Br and iHc of the R-T-B based magnet are extremely low.
- the content of Ga is preferably 0.01 to 0.5%. If the Ga content is less than 0.01% by weight, the effect of improving the coercive force cannot be obtained, and if the Ga content exceeds 0.5% by weight, the reduction of Br becomes remarkable.
- the content of Cu is preferably 0.01 to 1% by weight. Addition of a small amount of Cu can improve iHc. Saturation occurs when the Cu content exceeds 1% by weight. If the Cu content is less than 0.01% by weight, the effect of improving iHc is insufficient.
- the allowable amount of inevitable impurities is as follows: (1) Oxygen is 0.6% by weight or less, preferably 0.3% by weight or less, more preferably 0.2% by weight or less, with the total amount of RTB-based sintered magnets being 100% by weight. 2) not more than 0.2% by weight of carbon, preferably not more than 0.1% by weight; (3) not more than 0.08% by weight, preferably not more than 0.03% by weight of nitrogen; (4) not more than 0.02% by weight of hydrogen, preferably (5) Ca is 0.2% by weight or less, preferably
- Examples of the thin RTB magnet suitable for applying the electrolytic copper plating method of the present invention include an outer diameter of 2.3 to 4.0 mm, an inner diameter of 1.0 to 2.0 mm, and an axial length of 2.0 suitable for a vibration motor of a mobile phone or the like.
- Nd 25.0%
- Dy 1.5%
- B 1.0%
- Co 0.5%
- Ga 0.1%
- Cu 0.1%
- Fe 66.8 %
- An electrolytic nickel film was formed.
- the plating process is as follows.
- the R-T-B magnet was degreased with a degreaser (World Metal Co. Ltd., trade name: 200) at 30 ° C for 1 minute, and then washed with water.
- acid treatment was performed by immersion in a dilute nitric acid bath at room temperature for 2 minutes, followed by washing with water to clean the surface of the RTB-based magnet.
- the barrel tank containing the purified RTB magnet was placed in an alkaline copper sulfate plating bath containing 20 g / L copper sulfate and 30 g / L EDTA'2Na and having a pH of 10.6 (plating bath temperature: 70%). (° C), and electrolytic copper plating was performed at a current density of 1.5 A / dm 2 to form an electrolytic copper plating film having an average film thickness of ⁇ , and then washed with water.
- the Vickers hardness of the flat part was measured for each of the five samples with the exposed electrolytic copper plating film exposed, and the measured values of the five samples were averaged to obtain the Vickers hardness.
- the Vickers hardness was 310.
- the number of pinholes penetrating from the surface of the copper plating film to the surface of the RTB-based magnet was measured by the Fexyl xyl test method (JISH8617) for the sample where the electrolytic copper plating film was exposed. As a result, it was found that the number of pinholes in the electrolytic copper plating film was 0 / cm 2 .
- the adhesion between the base material of the R-T-B-based magnet and the plating film was evaluated by a peel test.
- a groove with a depth reaching the substrate was formed on the magnet surface in a rectangular shape with a length of 4 mm and a width of 50 mm using a force cutter knife.
- the force per unit length (adhesion) required to peel the plating film along the long side of the rectangular part surrounded by the groove was measured with a force gauge. In this way, the adhesion of a total of 20 Cu / Ni-plated R-T-B magnets was measured, and the average value was used as the adhesion.
- the peeling of each sample after the peel test occurred at the interface between the magnet substrate and the electrolytic copper plating film.
- the thermal demagnetization rate (thermal demagnetization resistance) was determined by using The appearance of the sample cooled to room temperature was sound.
- Example 1 The same method as in Example 1 was used to form an electrolytic copper plating film on the RTB magnet, followed by washing with water. The resultant was then placed in an electroless nickel plating solution at 80 ° C (Okuno Chemical Industries Co. Ltd., trade name: Nivojur). The substrate was immersed for 5 minutes, then washed with water and dried to form an electroless nickel plating film having an average film thickness of 8111. The obtained Cu / Ni-plated RTB-based magnet was evaluated in the same manner as in Example 1. Table 1 shows the results. As a result of the peel test, it was found that any peeling occurred at the interface between the magnet substrate and the electrolytic copper plating film. The appearance of the sample for thermal demagnetization measurement cooled to room temperature was sound.
- Example 4 The Vickers hardness of the electrolytic copper plating film, which was measured by the same method as in Example 1 for the sample where the electrolytic copper plating film was exposed, was 316, and the pinhole was 0 / cm 2 .
- Example 1 In the same manner as in Example 1 except that the electrolytic copper plating conditions and electrolytic nickel plating conditions shown in Table 1 were used, the electrolytic copper plating film ( An average film thickness of 10 / m) and an electrolytic nickel plating film (average film thickness of 8 / zm) were formed.
- Each of the obtained Cu / Ni-plated RTB-based magnets was evaluated in the same manner as in Example 1. Table 1 shows the results. As a result of the peel test, it was found that peeling occurred at the interface between the magnet substrate and the electrolytic copper plating film. The sample for thermal demagnetization measurement cooled to room temperature was sound.
- Example 5 Example 5
- Example 4 The same method as in Example 4 was used to form an electrolytic copper plating film on the RTB magnet and washed with water, and then applied to an electroless nickel plating solution at 80 ° C (Okuno Chemical Industries Co. Ltd., trade name: Nipoyur). After immersion for 60 minutes, washing and drying were performed to form an electroless nickel plating film having an average film thickness of 8 ⁇ .
- Each of the obtained Cu / Ni plated R-T-B based magnets was evaluated in the same manner as in Example 4. Table 1 shows the results. As a result of the peel test, it was found that any peeling occurred at the interface between the magnet substrate and the electrolytic copper plating film. The appearance of the sample for thermal demagnetization measurement cooled to room temperature was sound.
- the angle measured by the same method as in Example 1 was 290, and the Vickers hardness of the copper plating film was 290, and the number of pinholes was 0 / cm 2.
- An electroless copper plating film was formed on an RTB magnet in the same manner as in Example 4 and then washed with water.
- An electroless nickel plating solution at 90 ° C (Okuno Chemical Industries Co. Ltd., trade name: Top Nicoron F153) After immersion in water for 60 minutes, it was washed with water and dried to form an electroless nickel plating film having an average film thickness of 8 m.
- Each of the obtained Cu / Ni-plated RTB-based magnets was evaluated in the same manner as in Example 4. Table 1 shows the results. As a result of the peel test, it was found that the peeling occurred at V and the displacement occurred at the interface between the magnet substrate and the electrolytic copper plating film. The sample for thermal demagnetization measurement cooled to room temperature was sound.
- Example 7 Example 7
- Example 1 In the same manner as in Example 1, except that the copper plating conditions and electrolytic nickel plating conditions shown in Table 1 were used, electrolytic copper plating films (average film thickness ⁇ ) and An electrolytic nickel plating film (average film thickness 8 ⁇ ) was formed.
- the obtained Cu / Ni-plated RTB-based magnet was evaluated in the same manner as in Example 1. Table 1 shows the results. As a result of the pillar test, it was found that any peeling occurred at the interface between the magnet substrate and the electrolytic copper plating film. The appearance of the sample for thermal demagnetization measurement cooled to room temperature was sound.
- Example 8 The Vickers hardness of the electroless copper plating film measured by the same method as in Example 1 was 274, and the number of pinholes was 0 / cm 2 for the sample in which the electrolytic copper plating film was exposed.
- An electrolytic copper plating film was formed on an RTB magnet in the same manner as in Example 7 and then washed with water.
- An electroless Nigel plating solution at 80 ° C (Okuno Chemical Industries Co. Ltd., trade name: Nipoyule) ), Washed with water and dried to form an electroless nickel plating film having an average film thickness of 8 ⁇ m .
- Each of the obtained Cu / Ni-plated RTB-based magnets was evaluated in the same manner as in Example 7. Table 1 shows the results. As a result of the peel test, it was found that any peeling occurred at the interface between the magnet substrate and the electrolytic copper plating film. The appearance of the sample for thermal demagnetization measurement cooled to room temperature was sound.
- An electroless nickel plating solution at 90 ° C (Okuno Chemical Industries Co. Ltd., trade name: Top Nicoron F153) was prepared by forming an electrolytic copper plating film on an RTB magnet and washing with water in the same manner as in Example 7. After immersion in water for 60 minutes, the film was washed with water and dried to form an electroless nickel plating film having an average film thickness of 8 ⁇ .
- Each of the obtained Cu / Ni-plated RTB-based magnets was evaluated in the same manner as in Example 7. Table 1 shows the results. As a result of the peel test, it was found that the peeling occurred at V and the displacement occurred at the interface between the magnet substrate and the electrolytic copper plating film. The sample for thermal demagnetization measurement cooled to room temperature was sound.
- the Vickers hardness of the electrolytic copper plating film measured by the same method as in Example 1 was 280, and the number of pinholes was 0 / cm 2 .
- Example 1 A 10 vol.% Dilute sulfuric acid aqueous solution was added to adjust the pH of the electrolytic copper plating bath in Example 1. A 10 vol.% NaOH aqueous solution was added for adjusting the pH of the electrolytic copper plating baths of Examples 4 and 7. Comparative Example 1
- an appropriate amount of brightener Ebara Ujilight Co., Ltd., trade name: Cu board HA
- RTB magnet with copper plating contains 250 g / L of nickel sulfate, 40 g / L of nickel salt, 30 g / L of boric acid, and 1.5 g / L of saccharin (primary brightener). Then, it was immersed in a pet bath having a pH of 4.0 and a bath temperature of 47 ° C. to form an electrolytic nickel film having an average film thickness of 8 m at a current density of 0.4 A / dm 2 , followed by washing with water and drying. The same evaluation as in Example 1 was performed on the obtained Cu / Ni-plated RTB-based magnet. Table 2 shows the results.
- the number of pinholes in the electrolytic plating film measured in the same manner as in Example 1 was 39 / cm 2 . Due to such a large number of pinholes, the Cu / Ni-plated RTB magnet was inferior in corrosion resistance and thermal demagnetization rate. Comparative Example 2
- RTB-based magnets treated with acid in the same manner as in Example 1 and then washed with water were mixed with 380 g / L of copper pyrophosphate, 100 g / L of pyrophosphoric acid, 3 ml / L of aqueous ammonia, and 1 ml / L of aqueous ammonia.
- Immerse in a copper pyrophosphate bath at 55 ° C and pH 9.0 containing a brightener (manufactured by Okuno Chemical Industries Co. Ltd., trade name: Pyrotop: PC), and have a current density of 0.4 A / dm 2
- an electrolytic copper plating film having an average thickness of 10 m was formed and washed with water.
- Example 2 An RTB-based magnet that had been acid-treated and washed with water in the same manner as in Example 1 was treated with a 350 g / L borofluoric acid and a bath temperature containing 20 g / L borofluoric acid at a bath temperature of 35 ° C and a pH of 0.5. It was immersed in a copper borofluoride plating bath to form an electrolytic copper plating skin with an average film thickness of 10 m at a current density of 0.4 A / dm2, and washed with water. Next, in the same manner as in Comparative Example 1, an electrolytic nickel plating film having an average film thickness of 8 ⁇ m was formed using a Watt bath. Table 2 shows the results of the evaluation of the obtained Cu / Ni-plated RTB-based magnet in the same manner as in Example 1.
- Figure 4 shows the X-ray diffraction pattern.
- the Vickers hardness of the electrolytic copper plating film measured in the same manner as in Example 1 was 251 and the number of pinholes was 0 / cm 2 . Comparative Example 5
- Formaldehyde acts as a reducing agent that supplies electrons to the copper ions in the electroless copper plating bath to precipitate copper on the surface of the R-T-B magnet substrate. For this reason, formaldehyde itself is oxidized during electroless copper plating to become impurity sodium formate (HCOONa) and accumulated in the electroless copper plating bath.
- Table 2 shows the results of evaluating the obtained Cu / Ni-plated R-T-B-based magnet in the same manner as in Example 1.
- Comparative Example 7 The composition of the electrolytic copper plating bath was 20 g / L of copper sulfate and 30 g / L of EDTA'2Na, and the amount of the 10 vol. 9.0, flashing can bath temperature 70 ° C, but except that the conditions ⁇ Pi current density 1.5 a / dm 2 was subjected to electrolytic copper plated in the same manner as in example 1, the remarkable precipitation of EDTA'2Na As a result, the electrolytic copper plating solution was decomposed, and satisfactory electrolytic copper plating could not be performed.
- An electrolytic copper plating film having an average film thickness of about 8 m was formed in the same manner as in Example 4 except that the plating time was set to A / dm 2 and the plating time was set to 80 minutes.
- an electrolytic nickel film having an average film thickness of 5 ⁇ m was formed in the same manner as in Example 4 except that the plating time was changed.
- the throwing power of the electrolytic copper plating film of the obtained Cu / Ni plating RTB magnet was good.
- Fig. 5 shows an example of the relationship between the adhesion of the plating film and the current density when plating with electrolytic copper. 5 that the current density during the electrolytic copper plated adhesion strength of plated coatings on 0.5 N / cm or more at 0.2 to 0.7 A / dm 2 is obtained, a current density of 0.3 to 0.7 A / dm 2 It can be seen that a plating film adhesion of more than 1.0 N / cm was obtained when In each of the RTB-based magnets with electrolytic copper plating at a current density of 0.2 to 0.7 A / dm 2 , peeling by the peel test occurred at the interface between the substrate and the electrolytic copper plating film.
- Example 11 The Vickers hardness of the electrolytic copper plating film measured by the same method as in Example 1 was 298 and the number of pinholes was 0 / cm 2 for the sample having the exposed electrolytic copper plating film.
- It has the same main component composition as the RTB magnet of Example 10, and has a diameter dipole anisotropy of the shape shown in Fig. 2 (a) with an outer diameter of 2.5 mm, an inner diameter of 1.2 mm, and a length in the axial direction of 5.0 mm.
- a predetermined number of barrel tanks containing 1000 RTB-based sintered ring magnets were prepared. Each palle The bath was immersed in an electrolytic copper plating bath with a current density of 0.45 A / dm 2 and plating times of 5 min, 10 min, 20 min, 40 min, 60 min, 70 min, 80 min, and 90 min.
- An electrolytic copper plating film was formed on an RTB-based sintered ring magnet in the same manner as in Example 4 except that the electrolytic nickel plating film (average film thickness 5 ⁇ ) was formed in the same manner as in Example 10. Then, an RTB magnet with electrolytic copper plating for a vibration motor was fabricated. The average thickness of the electrolytic copper plating film was almost proportional to the plating time. The plating time was 3 ⁇ for 20 minutes, 5 ⁇ for 40 minutes, and 8 ⁇ m for 80 minutes.
- the appearance of 1000 samples (Cu / Ni plated R-T-B based magnets) 1 in each barrel tank obtained by successively performing electrolytic copper plating and electrolytic nickel plating was inspected. As a result, the surface of each sample was sound and no dents were observed as shown in Fig. 2 (a).
- the dent 2, if present, has the form illustrated in FIG. 2 (b). Assuming that the maximum length of the opening of the dent 2 is the size of the dent 2, if the size of the dent 2 is 50 ⁇ m or more (usually about 50 to 500 ⁇ ), problems such as poor appearance and poor corrosion resistance occur. .
- the plated R-T-B magnet 1 with the size of the dent 2 less than 50 m is practically acceptable and can be put to practical use.
- Fig. 6 plots the relationship between the obtained thermal demagnetization rate (%) and the electrolytic copper plating time (minutes).
- the plot (country) of 0 minute plating time in Fig. 6 shows the thermal demagnetization rate of the sintered ring magnet material.
- the nickel plating film was removed from the surface of each R-T-B magnet for the vibration motor by etching in the same manner as in Example 1 to prepare a sample in which the electrolytic copper plating film was exposed.
- a predetermined number of barrel tanks containing 1000 RTB sintered ring magnets with a dipole anisotropy of 2.5 mm outer diameter x 1.2 mm inner diameter and 5.0 mm length in the X-axis direction were prepared. Under the conditions, only the electrolytic copper plating treatment was performed for 5 to 90 minutes, and a plurality of samples having only the electrolytic copper plating film were produced. As a result of an appearance inspection of each of these 1000 samples, all had a healthy appearance and no dents were observed. An arbitrary sample of each sample was sampled, and the thermal demagnetization rate was measured in the same manner as in Example 1.
- Figure 6 plots the relationship between the thermal demagnetization rate (%) and the electrolytic copper plating time (minutes).
- Fig. 7 (a) shows a scanning electron micrograph of the cross-sectional structure
- Fig. 7 (b) shows a scanning electron micrograph of the cross-sectional structure at the center on the inner diameter side. From FIGS. 7 (a) and (b), it can be seen that the electrolytic copper plating film has almost the same film thickness on the outer diameter side and the inner diameter side, and has good throwing power.
- the thickness of the electrolytic nickel plating film in the second layer bath was about 1/5 of the film thickness on the inner diameter side of the outer diameter side, but it can withstand practical use.
- the nickel plating film is removed by etching from the surface of the RTB magnet that has an electrolytic copper plating film with an average film thickness of 9 ⁇ m and an electrolytic nickel plating film with an average film thickness of 5 IX m to expose the electrolytic copper plating film.
- Example 2 From the same RTB sintered magnet used in Example 1, a magnet piece for a CD pickup was cut out. The magnet pieces were degreased and washed with water. Next, it was immersed in a dilute nitric acid bath at room temperature and then washed with water to clean the surface of the RTB magnet piece. After 500 pieces of the cleaned RTB magnet pieces were put into the barrel tank, the surface of the RTB magnet pieces was sequentially applied in the same manner as in Example 4. Form a secondary electrolytic copper plating film (average film thickness lO m) and an electrolytic nickel plating film (average film thickness 8 ⁇ ), and prepare a 3.0 mm long, 3.0 mm wide, 1.5 mm thick Cu for CD pick-up. / Ni-plated RTB magnet (thickness direction is anisotropic direction) was prepared.
- a secondary electrolytic copper plating film average film thickness lO m
- an electrolytic nickel plating film average film thickness 8 ⁇
- the electrolytic copper plating film of this sample had no pinholes, had a Vickers hardness of 295, had no dents, had good adhesion, and had a substantially uniform film thickness. Comparative Example 8
- the electrolytic nickel plating film or the electroless nickel plating film was formed on the electrolytic copper plating film, but the present invention is not limited to this.
- Ni-Cu based alloy, Ni-Sn based alloy, Ni-Zn based alloy, Sn-Pb based alloy, Sn, Pb, Zn, ZirFe based alloy, Zn'Sn Good corrosion resistance, thermal demagnetization resistance, and scratch resistance can be obtained by forming at least one type of plating film selected from the group consisting of a base alloy, Co, Cd, Au, Pd, and Ag. .
- EDTA was used as the chelating agent.
- the chelating agent is not limited to this, and the same effect as in the above embodiment can be obtained even if an electrolytic copper plating solution containing a chelating agent other than EDTA is used.
- the method for plating electrolytic copper according to the present invention provides an RTB having a main phase of R 2 Ti 4 B intermetallic compound (R is at least one rare earth element including Y and T is Fe or Fe and Co). It is also effective for system warm-worked magnets. It is also effective for SmCo 5 or Sm 2 Coi 7 based sintered magnets. Industrial availability '14
- the electrolytic copper plating method of the present invention it is possible to form an electrolytic copper plating film having a substantially uniform film thickness, excellent adhesion, no pinholes, and excellent in scratch resistance and heat demagnetization resistance, and is highly toxic. Since a plating solution containing no cyanide is used, safety is high and plating solution treatment is easy.
- the R-T-B-based magnet formed with the electrolytic copper plating film by the electrolytic copper plating method of the present invention has excellent oxidation resistance and appearance, and is suitable for thin or small high-performance magnet applications.
Description
Claims
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US10/070,389 US6866765B2 (en) | 2000-07-07 | 2001-07-04 | Electrolytic copper-plated R-T-B magnet and plating method thereof |
EP01947811.4A EP1300489B1 (en) | 2000-07-07 | 2001-07-04 | Electrolytic copper-plated r-t-b magnet and plating method thereof |
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- 2001-07-04 CN CNB018019374A patent/CN1193115C/zh not_active Expired - Lifetime
- 2001-07-04 US US10/070,389 patent/US6866765B2/en not_active Expired - Lifetime
- 2001-07-04 WO PCT/JP2001/005798 patent/WO2002004714A1/ja active Application Filing
- 2001-07-04 KR KR1020027002972A patent/KR100720015B1/ko active IP Right Grant
- 2001-07-04 EP EP01947811.4A patent/EP1300489B1/en not_active Expired - Lifetime
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Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2007091602A1 (ja) * | 2006-02-07 | 2007-08-16 | Hitachi Metals, Ltd. | 銅めっき被膜を表面に有する希土類系永久磁石の製造方法 |
Also Published As
Publication number | Publication date |
---|---|
US6866765B2 (en) | 2005-03-15 |
KR20020029944A (ko) | 2002-04-20 |
CN1193115C (zh) | 2005-03-16 |
EP1300489B1 (en) | 2017-06-07 |
EP1300489A4 (en) | 2006-10-04 |
US20030052013A1 (en) | 2003-03-20 |
EP1300489A1 (en) | 2003-04-09 |
CN1386146A (zh) | 2002-12-18 |
KR100720015B1 (ko) | 2007-05-18 |
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