Patents Assigned to Dowa Mining Co., Ltd.
  • Patent number: 7351372
    Abstract: As a raw material of a copper base alloy containing at least one of 0.2 to 12 wt % of tin and 8 to 45 wt % of zinc, at least one of a copper base alloy having a large surface area and containing carbon on the surface thereof, a copper base alloy having a liquidus line temperature of 1050° C. or less, a copper base alloy surface-treated with tin, and a copper base alloy containing 20 to 1000 ppm of carbon, is used for obtaining a copper base alloy having an excellent hot workability. If necessary, when the raw material of the copper base alloy is melted, the material of the copper base alloy may be coated with a solid material containing 70 wt % or more of carbon, or 0.005 to 0.5 wt % of a solid deoxidizer having a stronger affinity with O than C with respect to the weight of the molten metal may be added to the molten metal.
    Type: Grant
    Filed: September 22, 2003
    Date of Patent: April 1, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Yasuo Inohana, Akira Sugawara, Toshihiro Sato
  • Patent number: 7348493
    Abstract: A metal-ceramic circuit board is characterized by being constituted by bonding directly on a base plate of aluminum or aluminum alloy at least one of ceramic substrate boards having a conductive metal member of an electronic circuit. The base plate has a proof stress not higher than 320 (MPa) and a thickness not smaller than 1 mm.
    Type: Grant
    Filed: May 3, 2001
    Date of Patent: March 25, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Hideyo Osanai, Masahiro Furo
  • Patent number: 7345418
    Abstract: A phosphor mixture containing four or more kinds of phosphors including a red phosphor, an orange phosphor, a blue phosphor, and a green phosphor, to produce emission having excellent color rendering of white light at a high color temperature, and emission in warm white which is low in color temperature, and a light emitting device including the phosphor mixture and a light-emitting section, CaAlSiN3:Eu and CaAl2Si4N8:Eu are manufactured as a red phosphor and an orange phosphor respectively, and ZnS:Cu, Al, and BAM:Eu are prepared as a green phosphor and a blue phosphor respectively. The emission spectrums of these phosphors are measured and a relative mixing ratio at which the correlated color temperature of the phosphor mixture becomes a targeted color temperature is determined from the emission spectrum by simulation, and a phosphor mixture is obtained by weighing and mixing the respective phosphors based on the simulation result.
    Type: Grant
    Filed: November 10, 2004
    Date of Patent: March 18, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Akira Nagatomi, Masahiro Gotoh, Kenji Sakane
  • Patent number: 7340828
    Abstract: There is provided a method for producing a metal/ceramic bonding circuit board, which can form a fine pattern even if a circuit forming metal plate is thick and which can shorten the time required to carry out etching, when a molten metal is caused to contact to a ceramic substrate to be cooled and solidified to bond the circuit forming metal plate to the ceramic substrate to etch the circuit forming metal plate to form a metal circuit plate having a desired circuit pattern. A molten metal is caused to contact both sides of a ceramic substrate 10 to be cooled and solidified. Thus, a circuit forming metal plate 12 having a shape similar to a desired circuit pattern is bonded to one side of the ceramic substrate 10, and a metal base plate 14 is bonded to the other side thereof.
    Type: Grant
    Filed: September 22, 2004
    Date of Patent: March 11, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Hideyo Osanai, Makoto Namioka, Susumu Ibaraki
  • Patent number: 7332220
    Abstract: An iron nitride magnetic powder consisting primarily of Fe16N2 phase whose average particle diameter determined by particle size measurement using a TEM micrograph is 20 nm or less and whose geometric standard deviation of the particle diameter is 1.4 or less. The iron nitride magnetic powder can be obtained by a method of producing an iron nitride magnetic powder consisting primarily of Fe16N2 phase includes a step of, at the time of producing an iron nitride magnetic powder consisting primarily of Fe16N2 phase by subjecting a reduced powder obtained by reduction of iron oxide to ammonia treatment, using goethite containing Al in solid solution as the iron oxide.
    Type: Grant
    Filed: February 25, 2005
    Date of Patent: February 19, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Kenji Masada, Takafumi Amino, Akira Nagatomi
  • Patent number: 7314666
    Abstract: An iron nitride system magnetic powder comprising of particles comprised primarily of Fe16N2 (having an average particle diameter of up to 25 nm, for example) is provided, to which one or more elements selected from Si, P and Ti is adhered. The powder has a C/Fe atomic ratio of 0.5 to 30%, preferably a (Si+P+Ti)/Fe atomic ratio of 0.1 to 10%. With ?Hc defined (Hc0·Hc1)/Hc0×100, the powder has a ?Hc of up to 5%, and with ??s defined as (?s0·?s1)/?s0×100, a ??s of up to 20%. The powder can provide an ignition temperature of 140° C. or above, and a tap density of 1.0 g/cm3 or above. Hc0 and ?s0 are the coercive force (kA/m) and saturation magnetization (Am2/kg), respectively, of the iron nitride system magnetic powder after adhesion, and Hc1 and ?s1 are the coercive force (kA/m) and saturation magnetization (Am2/kg), respectively, of the powder after it has been stored in a thermo-hygrostat for one week at a temperature of 60° C. and a relative humidity of 90%.
    Type: Grant
    Filed: December 20, 2005
    Date of Patent: January 1, 2008
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Kenji Masada, Hiroshi Kimura, Takafumi Amino
  • Patent number: 7304378
    Abstract: There is provided an aluminum/ceramic bonding substrate having a high reliability to high-temperature heat cycles. An aluminum member of an aluminum alloy having a Vickers hardness of 35 to 45 is bonded to a ceramic substrate having a flexural strength of 500 to 600 MPa in three-point bending. The ceramic substrate is made of high-strength aluminum nitride, silicon nitride, alumina containing zirconia, or high-purity alumina. The aluminum alloy is an aluminum alloy containing silicon and boron, or an aluminum alloy containing copper.
    Type: Grant
    Filed: August 19, 2005
    Date of Patent: December 4, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventor: Hideyo Osanai
  • Patent number: 7276292
    Abstract: An insulating substrate board for a semiconductor of the present invention comprises a ceramic substrate board (2) and a metal alloy layer (3) consisting of aluminum formed on one surface portion of the ceramic substrate board (2), wherein the Vickers hardness of the metal alloy layer (3) is not less than 25 and not more than 40. The metal alloy layer (3) includes silicon of not less than 0.2% by weight and not more than 5% by weight. The ceramic substrate board (2) is made of a material selected from a group consisting of alumina. aluminum nitride, and silicon nitride.
    Type: Grant
    Filed: March 1, 2002
    Date of Patent: October 2, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Masahiro Furo, Hideyo Osanai
  • Patent number: 7273405
    Abstract: A method of producing a sintered rare earth magnetic alloy wafer comprises a step of using a cutter to slice a wafer of a thickness of not greater than 3 mm from a sintered rare earth magnetic alloy having ferromagnetic crystal grains surrounded by a more readily grindable grain boundary phase and a step of surface-grinding at least one cut surface of the obtained wafer with a grindstone to form at a surface layer thereof flat ferromagnetic crystal grain cross-sections lying parallel to the wafer planar surface. The method enables high-yield production of a sintered rare earth magnetic alloy wafer having flat surfaces.
    Type: Grant
    Filed: September 16, 2005
    Date of Patent: September 25, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Kiyoshi Yamada, Hirofumi Takei, Masami Kamada, Toshinori Eba
  • Patent number: 7273568
    Abstract: A phosphor including a main production phase of a phosphor expressed by a composition formula of MmAaBbOoNn:Zz (where an element M is one or more bivalent elements, an element A is one or more trivalent elements, an element B is one or more tetravalent elements, O is oxygen, N is nitrogen, an element Z is an activator, n=2/3m+a+4/3b?2/3o, m/(a+b)?1/2, (o+n)/(a+b)>4/3, wherein m=a=b=1 and o and n is not 0). A phosphor including 24 wt % to 30 wt % of Ca (calcium), 17 wt % to 21 wt % of Al (aluminum), 18 wt % to 22 wt % of Si (silicon), 1 wt % to 15 wt % of oxygen, 15 wt % to 33 wt % of nitrogen and 0.01 wt % to 10 wt % of Eu (europium), wherein an emission maximum in an emission spectrum is in a range of 600 nm to 660 nm; and wherein color chromaticity x of light emission is in a range of 0.5 to 0.7, and color chromaticity y of the light emission is in a range of 0.3 to 0.5.
    Type: Grant
    Filed: August 20, 2004
    Date of Patent: September 25, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Akira Nagatomi, Masahiro Gotoh, Kenji Sakane, Shuji Yamashita
  • Patent number: 7256476
    Abstract: There is provided a notched compound semiconductor crystal having the same specification even if it is turned over. With respect to a compound semiconductor wafer produced by slicing a compound semiconductor crystal having a crystal plane of (100) plane, the crystal is sliced so as to be tilted from the (100) plane in a direction of [101] or [10-1] when a notch is formed in a direction of [010], or the crystal is sliced so as to be tilted from the (100) plane in a direction of [0-10] or [010] when a notch is formed in a direction of [001], or the crystal is sliced so as to be tilted from the (100) plane in a direction of [001] or [00-1] when a notch is formed in a direction of [0-10] , or the crystal is sliced so as to be tilted from the (100) plane in a direction of [010] or [0-10] when a notch is formed in a direction of [00-1].
    Type: Grant
    Filed: November 7, 2005
    Date of Patent: August 14, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Ryuichi Toba, Naoya Sunachi
  • Patent number: 7255807
    Abstract: A ferrite magnetic powder for bond magnet that experiences only small decrease in coercivity when molded into a bond magnet is provided, which is a ferrite magnetic powder that includes an alkaline-earth metal constituent and exhibits a decrease in coercivity of not greater than 600 Oe when subjected to a prescribed molding test. The magnetic powder can be obtained by mixing a fine ferrite powder of an average particle diameter of greater than 0.50 to 1.0 ?m and a coarse ferrite powder of an average particle diameter of greater than 2.50 to 5.0 ?m at ratio to incorporate the fine powder at a content ratio of 15-40 wt %.
    Type: Grant
    Filed: April 22, 2004
    Date of Patent: August 14, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Masayasu Senda, Shinichi Suenaga, Keisuke Ayabe, Toshiyuki Sakai
  • Patent number: 7255931
    Abstract: When an aluminum plate is bonded directly to a ceramic substrate by cooling and solidifying molten aluminum which is injected into a mold so as to contact the ceramic substrate arranged in the mold, an additive, such as a TiB alloy, Ca or Sr, for decreasing the grain size of the aluminum plate to 10 mm or less while preventing the drop in thermal conductivity of the aluminum plate from the thermal conductivity of a pure aluminum plate from exceeding 20% of the thermal conductivity of the pure aluminum plate is added to the molten aluminum. When an aluminum alloy plate of an aluminum-silicon alloy is bonded directly to a ceramic substrate by cooling and solidifying a molten aluminum-silicon alloy which is injected into a mold so as to contact the ceramic substrate arranged in the mold, an aluminum-silicon alloy containing 0.1 to 1.5 wt % of silicon and 0.03 to 0.10 wt % of boron is injected into the mold.
    Type: Grant
    Filed: September 29, 2004
    Date of Patent: August 14, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Hideyo Osanai, Satoru Ideguchi
  • Patent number: 7256353
    Abstract: There is provided a metal/ceramic bonding substrate capable of preventing the reverse thereof from greatly warping so as to be concave even if it is heated for soldering. In the metal/ceramic bonding substrate, a metal circuit plate 12 is bonded to one side of a ceramic substrate 10, and a heat sink plate (metal base plate) 14 is bonded to the other side thereof. On the heat sink plate 14, a work-hardened layer 16 is formed by shot peening. On the metal circuit plate 12 of the metal/ceramic bonding substrate, semiconductor chips (Si chips) 18 are soldered (solder layer 20). Then, a power module is produced by a predetermined process. On the reverse (the side of the work-hardened layer 16) of the power module, a radiating fin 26 is mounted via a thermal grease 24 by means of screws 22 or the like.
    Type: Grant
    Filed: December 29, 2003
    Date of Patent: August 14, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Hideyo Osanai, Susumu Ibaraki, Ken Iyoda, Makoto Namioka
  • Patent number: 7256478
    Abstract: There is provided a notched compound semiconductor crystal having the same specification even if it is turned over. With respect to a compound semiconductor wafer produced by slicing a compound semiconductor crystal having a crystal plane of (100) plane, the crystal is sliced so as to be tilted from the (100) plane in a direction of [101] or [10-1] when a notch is formed in a direction of [010], or the crystal is sliced so as to be tilted from the (100) plane in a direction of [0-10] or [010] when a notch is formed in a direction of [001], or the crystal is sliced so as to be tilted from the (100) plane in a direction of [001] or [00-1] when a notch is formed in a direction of [0-10], or the crystal is sliced so as to be tilted from the (100) plane in a direction of [010] or [0-10] when a notch is formed in a direction of [00-1].
    Type: Grant
    Filed: November 7, 2005
    Date of Patent: August 14, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Ryuichi Toba, Naoya Sunachi
  • Patent number: 7256477
    Abstract: There is provided a notched compound semiconductor crystal having the same specification even if it is turned over. With respect to a compound semiconductor wafer produced by slicing a compound semiconductor crystal having a crystal plane of (100) plane, the crystal is sliced so as to be tilted from the (100) plane in a direction of [101] or [10-1] when a notch is formed in a direction of [010], or the crystal is sliced so as to be tilted from the (100) plane in a direction of [0-10] or [010] when a notch is formed in a direction of [001], or the crystal is sliced so as to be tilted from the (100) plane in a direction of [001] or [00-1] when a notch is formed in a direction of [0-10], or the crystal is sliced so as to be tilted from the (100) plane in a direction of [010] or [0-10] when a notch is formed in a direction of [00-1].
    Type: Grant
    Filed: November 7, 2005
    Date of Patent: August 14, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Ryuichi Toba, Naoya Sunachi
  • Publication number: 20070181858
    Abstract: There is provided a method for producing a silver powder having excellent dispersibility and capable of forming a paste which do not form suspended matters by phase separation and which is printed on a substrate to form a film having a uniform thickness. In this method, an alkali or a complexing agent is added to an aqueous silver salt containing solution to form a silver oxide containing slurry or an aqueous silver complex salt containing solution. After or before silver particles are deposited by reduction by adding a reducing agent to the silver oxide containing slurry or aqueous silver complex salt containing solution while stirring it, at least one chelating agent selected from the group consisting of compounds having an azole structure, dicarboxylic acids, hydroxy carboxylic acids and salts thereof is added to a silver power containing slurry solution as a dispersing agent.
    Type: Application
    Filed: April 17, 2007
    Publication date: August 9, 2007
    Applicant: DOWA MINING CO., LTD.
    Inventors: Hiroshi Matsushima, Kozo Ogi
  • Patent number: 7252788
    Abstract: A phosphor with high efficiency having an excitation band corresponding to light of the ultraviolet-visible (300 to 550 nm) wavelength region emitted from a light emitting portion which emits blue or ultraviolet light is provided. A nitride of Ca, a nitride of Al, a nitride Si, and an oxide of Eu are prepared, and respective raw materials are weighed so that a mol ratio of respective elements becomes Ca:Al:Si:Eu=0.985:3:1:0.015, mixed under a nitrogen atmosphere, and thereafter fired at 1500° C. in a nitrogen atmosphere to thereby produce a phosphor having a composition formula Ca0.985SiAlN3:Eu0.015.
    Type: Grant
    Filed: August 20, 2004
    Date of Patent: August 7, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Akira Nagatomi, Kenji Sakane, Masahiro Gotoh, Shuji Yamashita
  • Patent number: 7241501
    Abstract: An iron nitride magnetic powder comprised primarily of Fe16N2 phase is characterized in that its coercive force Hc is 200 KA/m or greater and bulk switching field distribution BSDF is 2 or less. The magnetic powder can be produced by allowing a nitriding reaction of Fe particles with a nitrogen-containing gas for producing nitrided particles of primarily Fe16N2 phase to proceed under an increased pressure of 0.1 MPa or greater. The enhanced properties of the iron nitride magnetic powder make it suitable as a magnetic material for high-density magnetic recording media.
    Type: Grant
    Filed: November 19, 2004
    Date of Patent: July 10, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Kenji Masada, Takafumi Amino, Akira Nagatomi
  • Patent number: 7238432
    Abstract: There is provided a metal member capable of realizing a corrosion resistance and wear resistance, which are equivalent to or better than those when expensive PdNi is used even if PdNi is not used, and of being produced at relatively low costs. A first layer essentially consisting of nickel and unavoidable impurities is formed on the surface of a base metal member. On the first layer, a second layer essentially consisting of nickel, phosphorus and unavoidable impurities is formed. On the second layer, a third layer essentially consisting of a noble metal or an alloy thereof is formed. The second layer contains 10 to 15 wt % of phosphorus. The thickness of the first layer is 3 ?m or more, and the thickness of the second layer is 0.1 ?m or more.
    Type: Grant
    Filed: August 10, 2004
    Date of Patent: July 3, 2007
    Assignee: Dowa Mining Co., Ltd.
    Inventor: Naoki Haketa