JP2009280879A - Sputtering apparatus for magnetic powder coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sputtering apparatus for magnetic powder coating capable of coating the surface of powder having magnetism with various metals by a sputtering method. <P>SOLUTION: The sputtering apparatus for powder coating coats the powder having magnetism within a rotary drum held in a vacuum with sputtering particles. The non-magnetic powder of austenitic stainless steel having characteristics of ≤1.2 in permeance is packed into a semi-cylindrical cavity section formed of a semi-cylindrical casing and a housing. A backing plate, a magnet, and a cooling water passage, and a sputtering unit provided with a target plate and a skirt for preventing adhesion of powder are attached to the lower side of the housing, and the surface of the target plate is installed in a position further from the center of rotation of the drum with respect to the packed magnetic powers. A powder impeller is installed within the rotary drum. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a sputtering apparatus for use in coating magnetic powder with sputtered particles in a rotating drum kept in a vacuum.

  When metal is coated on the surface of various powders such as metals, ceramics, and plastics, powders with new characteristics can be produced. For example, if diamond powder is coated with copper, sintering is facilitated, thermal conductivity is improved, and, furthermore, diamond oxidative decomposition due to frictional heat is prevented, so that a diamond tool having a long life can be manufactured. Further, nickel powder coated with gold has low electrical resistance, excellent corrosion resistance, and is cheaper than gold powder, and is therefore often used as a conductive filler for liquid crystal panels and printed circuit boards.

  Known methods for coating powder include electroless plating and dry coating.

  The electroless plating method is a method in which powder is suspended and electroplating or electroless plating is performed. In the case of the electroless plating method, the surface of the metal powder is subjected to alkali degreasing treatment and pickling treatment in advance, and then a catalyst application treatment with a palladium chloride aqueous solution is performed as the first layer to ensure adhesion, and then as the second layer. An electroless gold plating layer is formed thereon. Thus, the conventional plating technique to the powder surface is a wet coating method using various aqueous solutions. However, in order to obtain products with stable quality by this method, it is necessary to strictly control the reaction temperature and reaction rate against changes with time of the metal ion concentration in these various aqueous solutions. There is a problem that there is. Furthermore, many processing steps such as washing with water, filtration, drying, classification, and waste liquid treatment are necessary, which causes a problem that the manufacturing cost becomes expensive. Moreover, since this electroless plating method is simply adhesion of metal ions by oxidation / reduction reactions, the adhesion between the plating film and the powder surface is not strong, and there are also problems such as many film defects such as cracks and pinholes. . If there are many defects such as cracks and pinholes in the plating film, the conductivity changes with time and partial conduction failure is likely to occur, so that the reliability of the entire electronic component to be used is remarkably deteriorated.

  On the other hand, dry coating methods include methods such as vacuum deposition, CVD, and sputtering. However, the melting point of gold is 1066 ° C, the boiling point is 2,857 ° C, the melting point of silver is 961 ° C, and the boiling point is 2,163 ° C. Is extremely difficult technically. In addition, since no gold or silver compound is thermally decomposed at a high temperature and deposited as a film, it is technically difficult to coat the powder by the CVD method.

  On the other hand, the sputtering method is not a method for vapor-depositing a metal at a high temperature, nor is a method for thermally decomposing a metal compound at a high temperature. The sputtering method applies high-frequency electricity to cause metal atoms excited to a high-energy plasma state to collide with the powder surface at high speed, so that various metals can be firmly coated on the powder surface. In addition, since it is a dry coating method using vacuum technology, there is an advantage that the manufacturing process can be greatly shortened. In addition, since a large amount of waste liquid is not generated, there is a great advantage that the manufacturing cost is reduced and it is friendly to the global environment.

  The basic principle of the method of coating the surface of the powder by sputtering is described, for example, in Patent Document 1 below, and is already known. Since then, many device patents such as the following Patent Documents 2 to 5 have been published. The present inventors have also introduced a rotating drum type sputtering apparatus in Patent Document 6 below.

  What is generally common to these known powder coating sputtering apparatuses is, for example, a structure as shown in FIGS. FIG. 1 is an overall configuration diagram of a known powder coating sputtering apparatus. As shown in FIG. 1, the basic configuration of a known powder coating sputtering apparatus is such that powder is accommodated in a rotating drum 3 containing a sputtering unit 2 connected to a high-frequency power source 1. Is a device that holds the vacuum by the vacuum exhaust device 4.

  The rotating drum 3 is supported by a drive roll 5a and a driven roll 5b. The drive roll 5a receives power from the drive motor 5 and rotates the rotary drum 3 around the horizontal axis. The sputtering unit 2 is inserted into the rotating drum 3 by an arm 1b hermetically held by a vacuum seal type bearing 1a, and a target plate 6 slightly shorter than the axial length of the rotating drum 3 is disposed obliquely downward. Yes. In the airtight arm 1b, a target cooling water inlet 1c, a target cooling water outlet 1d, and an argon gas inlet 1e are incorporated. The rotary drum 3 is held in a vacuum by a vacuum exhaust device 4 which is airtightly held by a vacuum seal type bearing 4a.

  In the case of a non-magnetic powder, the powder is always gathered at the bottom of the rotating drum 3 by gravity, so that when the rotating drum 3 is rotated, the powder becomes fluid at the bottom surface. The coating particles are knocked out of the target plate 6 by the impact of argon atoms excited to the plasma state by the high frequency power source 1 and fly through the rotating drum 3 to adhere to the surface of the powder in the fluid state. To do. After the predetermined coating layer is formed, the rotary drum 3 is stopped, and the atmosphere is released to the atmosphere to take out the coated powder.

  FIG. 2 is a partial cross-sectional view of a rotating drum and a sputtering unit in a known powder coating sputtering apparatus. FIG. 3 is an enlarged cross-sectional view of a sputtering unit in a known powder coating sputtering apparatus.

  The sputtering unit 2 includes a semi-cylindrical casing 2 a and a target plate 6 that are produced concentrically with respect to the rotating drum 3. A reinforcing plate 2b is provided inside the semi-cylindrical casing 2a, and the internal cavity is divided into two cavities 2c and 2d by this plate.

  The reason why the inside of the semi-cylindrical casing 2a is semi-cylindrical is that it is necessary to make the volume inside the rotating drum 3 as small as possible in order to make the inside of the rotating drum 3 in a high vacuum state in a short time. It is. The cavities 2c and 2d filled with atmospheric air are semi-cylindrical in order to give sufficient pressure-resistant strength to the semi-cylindrical casing 2a even when the inside of the rotary drum 3 is in a high vacuum state. The reinforcing plate 2b is attached. In addition, this reinforcement plate 2b also has an effect which suppresses bending when the sputtering unit 2 is cantilever-supported.

  A housing 2f is fixed to both edge portions of the semi-cylindrical casing 2a via attachment fittings 2e. The housing 2f has a support plate 2g projecting vertically downward on both side edges. The backing plate 6a and the housing 2f are electrically disconnected by incorporating an insulating material into the mounting bracket 2e or making the support plate 2g insulative.

  The backing plate 6a is made of a material having good thermal conductivity such as copper or a copper alloy, and is sandwiched between the support plates 2g in order to cool the target plate 6 that is heated during sputtering. A plurality of recesses for accommodating the magnet 6b are formed on the back side of the backing plate 6a, and the target plate 6 is attached to the front side of the backing plate 6a by a mounting bracket 6d. In addition, a magnetic shield 6c is incorporated in the backing plate 6a so that magnetic flux does not leak from the backing plate magnet 6b to the outside. On the front side of the backing plate 6a, a shield cover 6e serving as a counter electrode when generating plasma is attached with a predetermined distance from the backing plate 6a. Further, a water cooling mechanism is disposed on the back side of the backing plate 6a. Here, the water cooling mechanism refers to the cooling water passage 2h surrounded by the backing plate 6a, the side plate 6f, and the front plate 6g. The side plate 6f is fixed to the backing plate 6a via the insulator 6h. During the sputtering, the semi-cylindrical casing 2a is set to the ground potential, and a high voltage is applied to the target plate 6 from the high frequency power source 1 through the backing plate 6a.

British Patent No. 14977782 JP-A-1-287202 JP-A-3-153864 JP-A-4-173955 JP-A-8-81768 JP-A-2-153068

  Recently, with the development of science and technology, high performance for applications such as "for conductive filler", "for automobile exhaust gas catalyst", "for fuel cell catalyst", "for sintered magnet" and "for metal powder injection molding" There is a need for new coating powders that are inexpensive and resource-saving.

  There is no problem when the non-magnetic powder is coated by a conventional powder coating sputtering apparatus. However, with this apparatus, the surface of the magnetic powder such as iron powder, nickel powder, cobalt powder, hard ferrite powder, soft ferrite powder, ferritic stainless steel powder or martensitic stainless steel powder is gold by sputtering, Coating various metals such as silver, platinum, copper, palladium, aluminum, or titanium has been technically difficult.

  The reason for this is that, in general, both DC type and RF type magnetron sputtering devices are shown in FIGS. 2 and 3 in order to increase the sputtering efficiency in order to contain argon gas plasma generated during sputtering by a magnetic field to create a higher density plasma. This is because a strong samarium / cobalt-based or indium / iron-based magnet 6b is disposed on the back surface of the target plate 6 as shown. More specifically, as shown in FIG. 2 and FIG. 3, when various metals are coated on the surface of the magnetic powder by sputtering, the magnetic powder adheres to the inner peripheral surface of the rotary drum 3 by rotation. It is lifted and falls from the top of the rotating drum 3. At that time, most of the magnetic powder Pa adheres and accumulates on the semi-cylindrical casing 2a due to the strong magnetic force of the magnet 6b. A part Pb of the magnetic powder spilled from the semi-cylindrical casing 2a adheres to the surface of the target plate 6 due to the strong magnetic force of the magnet 6b during the fall and causes abnormal discharge. Furthermore, the magnetic powder Pc gathered at the bottom of the rotating drum 3 due to gravity will aggregate due to the influence of a strong magnetic force. Further, in this case, since the surface of the target plate 6 is installed at a position closer to the rotation center point of the rotary drum than the magnetic powder Pc collected at the bottom of the rotary drum 3, it is agglomerated at the bottom due to the influence of a strong magnetic force. Then, a part of the raised magnetic powder Pc adheres to the surface of the target plate 6. As a result, it has been technically impossible to uniformly coat all the powders with the conventional powder coating sputtering apparatus.

  Therefore, the present invention solves the above-mentioned problems by further improving the internal structure of the powder coating sputtering apparatus according to the conventional method, and provides an apparatus capable of uniformly coating various metals on the surface of magnetic powder by sputtering. The purpose is to do.

  A sputtering apparatus for powder coating that coats magnetic powder with sputtered particles in a rotating drum held in vacuum according to the present invention includes: (1) a semi-cylindrical shape having a peripheral wall concentric with the inner peripheral surface of the rotating drum. An austenite having an average particle size of 50 μm or more and less than 300 μm in a semi-cylindrical cavity formed by a casing and a housing attached to the semi-cylindrical casing and having nonmagnetic properties and a magnetic conductivity of 1.2 or less (2) A backing plate in which a sputtering unit is attached to the lower side of the housing and insulated from the housing, and a magnet and a cooling water passage disposed between the backing plate and the housing. And a backing plate so as to face the magnetic powder charged in the rotating drum. (3) A sputtering unit is cantilevered by an arm inserted into a high-frequency power source and is provided on one side of a rotating drum. Is installed at a position farther from the rotation center point of the rotating drum than the magnetic powder charged on the surface of the target plate, and (4) a powder agitating blade is installed in the rotating drum. .

  As mentioned above, if the sputtering apparatus for powder coating by this invention is used, it will become possible to coat various metal efficiently and uniformly on the surface of the powder which has magnetism.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, it is needless to say that the present invention can be implemented in many different forms, and is not limited to the description shown in the following embodiments and examples.

  FIG. 4 is an overall configuration diagram of the powder coating sputtering apparatus according to the present embodiment, which is modified based on the structure of the known powder coating sputtering apparatus shown in FIG. FIG. 5 is a partial cross-sectional view of the rotating drum and the sputtering unit in the powder coating sputtering apparatus according to the present embodiment. FIG. 6 is an enlarged view of the sputtering unit in the powder coating sputtering apparatus according to the present embodiment. It is sectional drawing.

  The powder coating sputtering apparatus according to this embodiment can solve the above problems by taking the following three measures.

(1) Measures to prevent magnetic powder Pa adhering and depositing on semicylindrical casing 2a The cause of magnetic powder Pa adhering and accumulating on semicylindrical casing 2a is due to the strong magnetic force of magnet 6b. is there. As a result of diligent research on the above problems, the inventors of the present invention have an average particle diameter of 50 μm or more and less than 300 μm in the hollow portions 2c and 2d of the semi-cylindrical casing 2a. When the austenitic stainless steel powder 7 was filled, the influence of the magnetic force was drastically reduced, and the magnetic powder Pa was hardly adhered and deposited on the semi-cylindrical casing 2a.

  Here, magnetic conductivity is one of the characteristics of stainless steel. Usually, the strength of the magnetic field is indicated by the strength of the induced magnetism (Gauss) measured at 200 Oersted, and the larger the value, the stronger the magnetism. If this is 1.0, it means completely non-magnetic. As an austenitic stainless steel that is nonmagnetic and has a magnetic conductivity of 1.2 or less, SUS301, SUS302, SUS303, SUS304, SUS304L, SUS305, SUS309, SUS309S, SUS310, SUS310S, SUS316, SUS316L, SUS317L, SUS317L, Examples include SUS321, SUS330, and SUS347. Preferably, it is SUS304 or SUS304L, and a relatively inexpensive powder is commercially available. Iron powder, nickel powder, cobalt powder, hard ferrite powder, soft ferrite powder, ferritic stainless steel powder such as SUS430 or martensitic stainless steel powder such as SUS410 that has magnetism and has a magnetic conductivity greater than 1.2 Since it is not possible to weaken the magnetic force of a strong permanent magnet, it is not preferable to employ this embodiment.

  As the powder 7 filled in the hollow portions 2c and 2d in the semi-cylindrical casing 2a used in the present embodiment, these commercially available spherical powders manufactured by the gas atomization method are classified into a range in which the average particle diameter is 50 μm or more and less than 300 μm. Use what you did. A powder having an average particle size of less than 50 μm or 300 μm or more is expensive because the yield is extremely poor in the gas atomization method.

  Also, if the hollow portions 2c and 2d of the semi-cylindrical casing 2a are not filled with the austenitic stainless steel powder 7 and are all made of pure stainless steel, the shielding effect of the magnetic field lines can surely be maximized. However, since the weight becomes extremely heavy, there is a serious problem in terms of strength and life of the bearing 1a and arm 1b that are supported in a cantilever manner. In addition, it is not practical to cut out from thick stainless steel because the processing cost is extremely high.

  Moreover, in this embodiment, since the semi-cylindrical casing 2a is usually made of SUS304 series stainless steel, the sliding property of the powder is poor. Therefore, it is preferable to apply a fluororesin-based adhesive tape having excellent lubricity or a paint to the entire surface because the magnetic powder Pa is more difficult to adhere and deposit.

(2) Measures to prevent generation of magnetic powder Pb adhering to the surface of the target plate 6 A part of the magnetic powder Pb spilled from the semi-cylindrical casing 2a adheres to the surface of the target plate 6 during the fall. This is due to the strong magnetic force of 6b. Therefore, as a result of intensive studies, the present inventors have found that (A) the skirt 8 for preventing powder adhesion is installed on the outside of the support plate 2g, and (B) the surface of the target plate 6 against the magnetic powder charged. Is installed at a position farther from the rotational center point of the rotating drum, thereby preventing a part of the magnetic powder Pb spilled from the semi-cylindrical casing 2a from adhering to the surface of the target plate 6 during the fall. As a result, it has been found that abnormal discharge can be prevented.

  The material of the powder adhesion preventing skirt 8 must be electrically insulating, and must be excellent in heat resistance because it is exposed to high-temperature plasma, so a fluororesin-based polytetrafluoroethylene having a thickness of about 1 mm. A resin sheet is preferred. It is important that the powder adhesion preventing skirt 8 protrudes downward from the lower surface of the target plate 6 within a range of 10 mm to 30 mm. When the powder adhesion preventing skirt 8 is shorter than 10 mm from the lower surface of the target plate 6, it is possible to prevent a part Pb of the magnetic powder from adhering to the surface of the target plate 6 in the middle of dropping along the magnetic field lines. It becomes difficult. On the other hand, when the powder adhesion preventing skirt 8 is longer than 30 mm from the lower surface of the target plate 6, the problem arises that the plasma formed along the magnetic field on the surface of the target plate 6 is not stable. .

If the surface of the target plate 6 is placed at a position farther from the center of rotation of the rotary drum 3 than the charged magnetic powder, the distance between the magnet 6b and the magnetic powder Pc is increased. Becomes difficult to adhere to the surface of the target plate 6. This configuration also has the advantage that the amount of powder charged can be increased compared to known methods. In particular, it is possible to efficiently coat various metals on the surface of hard ferrite powder, soft ferrite powder, γ-alumina powder or silica powder having a small bulk density (0.2 g / cm ³ or less). In this case, it is preferable that the surface of the target plate 6 is separated from the rotation center point of the rotary drum 3 in a range of 10 mm to 50 mm. By setting it to 10 mm or more, a sufficient distance between the magnetic powder Pc and the target plate 6 can be secured, and it can be made difficult to adhere to the surface of the target plate 6. On the other hand, if the sputtering unit 2 is moved from the center of rotation of the rotating drum 3 to the upper part (depending on the dimensions), the size of the rotating drum 3 can be prevented from being significantly increased by being 50 mm or less. There are advantages.

(3) Measures to prevent generation of magnetic powder Pc that aggregates at the bottom of the rotating drum 3 due to the influence of a strong magnetic force The magnetic powder Pc that collects at the bottom of the rotating drum 3 due to gravity aggregates due to the influence of a strong magnetic force. Therefore, as a result of intensive studies, the present inventors have found that if the powder stirring blade 9 is installed in the rotating drum 3 and the magnetic powder Pc is forcibly stirred, it is possible to substantially prevent aggregation and swell.

  The powder agitating blade 9 is hermetically held by a vacuum seal type bearing 9a, and is oscillated within an angle range of ± α around the rotation axis of the rotary drum 3 by an oscillating type powder agitating motor 9b. Prevent aggregation of Pc. The material of the powder stirring blade 9 is preferably copper or SUS304 austenitic stainless steel. The rod is preferably a rod having a diameter of 3 mm or more and 10 mm or less, but a spherical shape, a granular shape, a lump shape, a crushed shape, a porous shape, an agglomerated shape, a flake shape, a spike shape, a filament shape, a fiber shape or a whisker shape. A paddle wing, a screw wing, a brush wing, a comb wing, a spiral wing, or the like can also be used according to characteristics such as powder shape, fluidity, and bulk density.

  The swinging motion of the powder agitating motor 9b can be easily performed by reversing the positive and negative of the electric circuit. The swing angle (± α) can be adjusted as appropriate, but is preferably 45 degrees. The rocking speed is usually preferably set to 1 to 3 reciprocations / minute. It is also preferable to adjust the rocking angle and rocking speed to optimum values according to the state of powder aggregation, and intermittent stirring may be used. If the swing angle and swing speed are set incorrectly, the magnetic powder Pc may not be agglomerated, or conversely, the magnetic powder Pc may rise and adhere to the surface of the target plate, causing abnormal discharge. is there.

  When gold or silver is coated by the conventional electroless plating method, phosphorus (P), boron (B), etc., which are decomposition products of the reducing agent, are mixed in the film, so the purity drops to 99 mass% or less. As a result, the electrical resistance value of the film becomes high and the workability and corrosion resistance become poor. However, when gold or silver is coated by sputtering, the target has a high purity of 99.9 mass% or more. Metal can be used, the electrical resistance value of the film is lowered, and the workability and corrosion resistance are also excellent. That is, if the sputtering apparatus for powder coating according to the present embodiment is used, various metals can be efficiently and uniformly coated on the surface of the magnetic powder.

  As the target plate 6, for example, gold, silver, palladium, platinum, rhodium, copper, aluminum, titanium, or austenitic stainless steel can be used. As the magnetic powder, for example, iron powder, nickel powder, cobalt powder, hard ferrite powder, soft ferrite powder, ferritic stainless steel powder such as SUS430 or martensitic stainless steel powder such as SUS410 may be used. it can. This device also uses various metal powders such as aluminum and copper that do not have magnetism, various ceramic powders such as alumina and silica, various plastic powders such as acrylic resin and polyester resin, and carbon black and activated carbon. be able to.

  Hereafter, the sputtering apparatus for powder coating which concerns on the said embodiment was produced, and the effect was confirmed. The main parts were set as follows.

(1) The hollow portion of the semi-cylindrical casing was filled with SUS304 austenitic stainless steel powder having an average particle size of 100 μm, which is nonmagnetic and has a magnetic conductivity of 1.2 or less.
(2) On the outer peripheral surface of the semi-cylindrical casing, a fluororesin-based adhesive tape (Chuco Flow adhesive tape, manufacturer: Chuko Kasei Kogyo Co., Ltd.) excellent in lubricity was attached.
(3) As the skirt for preventing powder adhesion, a fluororesin sheet (polytetrafluoroethylene resin, thickness: 1 mm) was used.
(4) The skirt for preventing powder adhesion was attached by protruding 20 mm downward from the lower surface of the target plate.
(5) The surface of the target plate was placed 10 mm farther from the center of rotation of the rotating drum than the charged nickel powder.
(6) As the powder stirring blade, a copper rod having a diameter of 5 mm was used.
(7) The rocking angle (± α) of the powder stirring blade was 30 degrees.
(8) The rocking speed of the powder stirring blade was set to 2 reciprocations / minute.

  First, a silver target plate (dimension: 10 mm thickness × 60 mm width × 150 mm length) was attached to the apparatus. Next, 200 g of spherical nickel powder (average particle size: 10 μm, manufacturer: INCO, type: CNS), which is a magnetic powder, was charged into a rotating drum.

The argon gas flow rate was set to 7 ccm, and while rotating the rotating drum at a speed of 2 rpm, the inside thereof was 1 × 10 ⁻¹ Pa. The degree of vacuum was adjusted.

  Further, sputtering was performed for 2 hours and 14 minutes at an output of 1 KW using a DC magnetron type sputtering power source. After the sputtering operation, the apparatus was stopped and the rotating drum was returned to atmospheric pressure.

  As a result, the surface of the spherical nickel powder can be coated with 15 mass% of silver, and the resulting coating powder has a high yield of 232 g (recovery rate: 98%). Each was uniformly coated with silver.

  Next, with the spherical nickel powder coated with 15 mass% of silver remaining in the rotating drum, the silver target plate is removed and replaced with a gold target plate (dimensions: 10 mm thick x 60 mm wide x 150 mm long) did.

And again, the flow rate of argon gas was set to 7 ccm, and while rotating the rotating drum at a speed of 2 rpm, the inside was 1 × 10 ⁻¹ Pa. The degree of vacuum was adjusted.

  Using a DC magnetron type sputtering power source, sputtering is performed at an output of 1 KW for 1 hour and 32 minutes so that a surface of spherical nickel powder coated with 15 mass% of silver is further in a state of two layers of 13 mass% of gold. It was coated again. The weight of the obtained two-layer coating powder was as high as 262 g (recovery rate: 98%), and most of the powder was uniformly coated with gold.

When the electrical resistance of this two-layer coating (upper layer: 13 mass% gold / lower layer: 15 mass% silver) spherical nickel powder was measured, it was extremely excellent at 1 × 10 ⁻⁵ (Ω · cm) as expected. It showed conductivity.

  Through this silver and gold sputtering operation, (1) magnetic powder deposited and deposited on the semi-cylindrical casing, (2) magnetic powder deposited on the surface of the target plate, and (3) rotating drum by the influence of strong magnetic force None of the magnetic powder agglomerated at the bottom was observed.

  The “gold / silver two-layer coating nickel powder” obtained in this example is a conductive filler having excellent pressure-resistance, workability, corrosion resistance, etc., and a small electric resistance value. However, since this filler is obtained by sandwiching inexpensive silver with low workability and corrosion resistance in the intermediate layer and low electrical resistance value, it was made into a novel conductive filler having excellent practical characteristics at low manufacturing cost. . In addition, precious gold resources could be saved.

  Furthermore, when the sputtering apparatus for powder coating according to the present embodiment is used, a conductive filler having a very long product life, such as “gold / tungsten / silver three-layer coated nickel powder”, “gold / iridium / silver three-layer coated nickel powder”. , “Gold / rhodium / silver three-layer coated nickel powder”, and “gold / ruthenium / silver three-layer coated nickel powder” can be produced. These newly developed products have excellent workability and corrosion resistance in the underlying layer of the coating layer, and low-priced silver with low electrical resistance. The intermediate layer is hard and extremely wear-resistant tungsten with low electrical resistance. , Iridium, rhodium, ruthenium, etc., and the surface layer is a hybrid material with the smallest electrical resistance coated with gold. The coating powder having such a complicated structure can never be produced by a conventional electroless plating method.

In this embodiment, nickel powder is coated with gold or silver, but various coatings as shown below are also possible.
(1) For conductive filler: gold-coated iron powder, silver-coated acrylic resin, palladium-coated silica powder, etc. (2) For fuel cell catalysts: platinum-coated carbon black, platinum / rhodium double-layer coated carbon nanotubes, etc. (3) Automotive exhaust gas catalyst For: platinum coated ferritic stainless steel powder, platinum / rhodium bilayer coating γ-alumina powder, etc. (4) For sintered magnets: copper coated soft ferrite powder, aluminum coated hard ferrite powder, etc. (5) For metal powder injection molding: SUS304 austenitic stainless steel coated iron powder, copper coated aluminum powder, titanium coated copper powder, etc.

  In this way, with this device, various metal powders such as aluminum and copper that do not have magnetism, various ceramic powders such as alumina and silica, various plastic powders such as acrylic resin and polyester resin, carbon black and activated carbon. Various coatings can also be applied to the surface.

(Comparative example)
A conventional powder coating sputtering apparatus as shown in FIGS. 1, 2 and 3 was used. The main parts were set as follows.
(1) Nothing was filled in the cavity of the semi-cylindrical casing.
(2) The powder adhesion prevention skirt was not used.
(3) A powder stirring blade was not used.

  Using this apparatus, the same sputtering operation as in the example was performed. First, the surface of spherical nickel powder was coated with 15 mass% of silver. The weight of the recovered coating powder was as low as 24 g (recovery rate: 10%), and most of the powder was not uniformly coated with silver. When the apparatus was observed after the sputtering of silver, (1) the weight of the magnetic powder deposited and deposited on the semi-cylindrical casing was 166 g (recovery rate: 70%), and (2) adhered to the surface of the target plate. The weight of the magnetic powder was 47 g (recovery rate: 20%) and (3) the weight of the magnetic powder agglomerated at the bottom of the rotating drum due to the strong magnetic force was 24 g (recovery rate: 10%).

  Next, the surface of the spherical nickel powder coated with 15 mass% of silver was further coated with 13 mass% of gold so as to be in two layers. The weight of the obtained two-layer coating powder was as low as 40 g (recovery rate: 15%), and most of the powder was not uniformly coated with gold. Observation after this gold sputtering operation revealed that (1) the weight of the magnetic powder deposited and deposited on the semi-cylindrical casing was 182 g (recovery rate: 67%), and (2) the magnetic powder deposited on the surface of the target plate. The weight of the magnetic powder was 49 g (recovery rate: 18%) and (3) the weight of the magnetic powder agglomerated at the bottom of the rotating drum due to the strong magnetic force was 40 g (recovery rate: 15%).

Moreover, when the electrical resistance of this two-layer coating (upper layer: 13 mass% gold / lower layer: 15 mass% silver) spherical nickel powder was measured, it was 1 × 10 ⁻¹ (Ω · cm), which was poor.

  The present invention has industrial applicability as a sputtering apparatus.

Overall configuration of a known powder coating sputtering system It is a fragmentary sectional view of a rotating drum and a sputtering unit in a known powder coating sputtering apparatus. It is an expanded sectional view of the sputtering unit in the well-known sputtering apparatus for powder coating. 1 is an overall configuration diagram of a powder coating sputtering apparatus according to an embodiment. It is a fragmentary sectional view of the rotating drum and sputtering unit in the sputtering device for powder coating concerning an embodiment. It is an expanded sectional view of the sputtering unit in the sputtering device for powder coating concerning an embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... High frequency power source 1a ... Vacuum seal type bearing 1b ... Arm 1c ... Target cooling water inlet 1d ... Target cooling water outlet 1e ... Argon gas inlet 2 ... Sputtering unit 2a ... Semi-cylindrical casing 2b ... Reinforcement plate 2c ... Hollow part (left)
2d ... hollow (right side)
2e ... Mounting bracket 2f ... Housing 2g ... Support plate 2h ... Cooling water passage 3 ... Rotating drum 4 ... Vacuum exhaust device 4a ... Vacuum seal type bearing 5 ... Drive motor 5a ... Drive roll 5b ... Following roll 6 ... Target plate 6a ... Backing Plate 6b ... Magnet 6c ... Magnetic shield 6d ... Mounting bracket 6e ... Shield cover 6f ... Side plate 6g ... Front plate 6h ... Insulator 7 ... Austenitic stainless steel powder 8 ... Skirt for preventing powder adhesion 9 ... Powder stirring blade 9a ... Vacuum Seal type bearing 9b ... Oscillating type powder agitation motor P ... Magnetic powder Pa ... Magnetic powder adhering on semi-cylindrical casing Pb ... Magnetic powder adhering to target plate surface Pc ... Magnetic powder agglomerated by magnetic force C ... Rotating drum Center of rotation

Claims (1)

A powder coating sputtering apparatus for coating magnetic powder with sputtered particles in a rotating drum held in a vacuum,
The semi-cylindrical cavity formed by the semi-cylindrical casing and the housing attached to the semi-cylindrical casing has an average particle diameter of 50 μm or more having non-magnetic properties and a magnetic conductivity of 1.2 or less. Filled with powder of austenitic stainless steel less than 300 μm,
A sputtering unit is attached to the lower side of the housing and insulated from the housing, a magnet and a cooling water passage disposed between the backing plate and the housing, and charged in the rotating drum. A target plate attached to the backing plate so as to face the magnetic powder, and a powder adhesion preventing skirt installed outside the support plate,
The sputtering unit is cantilevered by an arm inserted into a high-frequency power source and is loaded from one side of the rotating drum, and the surface of the target plate is farther from the center of rotation of the rotating drum than the loaded magnetic powder. In place
A sputtering apparatus for magnetic powder coating, wherein a powder stirring blade is installed in the rotary drum.