Patents Assigned to Dowa Mining Co., Ltd.
  • Publication number: 20030186071
    Abstract: The surface to be plated of a composite made of a metallic and a non-metallic material is degreased and otherwise cleaned and immersed in a palladium activator fluid conditioned with a hydrogencarbonate to a pH of 2˜5. After this pretreating process, the composite is plated with a metal and becomes most suitable for use as a material for heat sink on hybrid ICs since it can be efficiently soldered and has better corrosion resistance.
    Type: Application
    Filed: March 27, 2003
    Publication date: October 2, 2003
    Applicant: DOWA MINING CO., LTD.
    Inventors: Ken Iyoda, Susumu Shimada
  • Patent number: 6627011
    Abstract: Copper alloy having the basic composition Cu—Zn—Sn contains 23-28 wt % Zn and 0.3-1.8 wt % Sn and satisfies the relation 6.0≦0.25X+Y≦8.5 (where X is the addition of Zn in wt % and Y is the addition of Sn in wt %). The alloy is cast into an ingot by melting and cooling over the range from the liquidus line to 600° C. at a rate of at least 50° C./min; the ingot is hot rolled at a temperature not higher than 900° C. and then subjected to repeated cycles of cold rolling and annealing at 300-650° C. to control the size of crystal grains, thereby producing a rolled strip having a 0.2% yield strength of at least 600 N/mm2, a tensile strength of at least 650 N/mm2, an electrical conductivity of at least 20% IACS, a Young's modulus of no more than 120 kN/mm2 and a percent stress relaxation of no more than 20%.
    Type: Grant
    Filed: July 23, 2001
    Date of Patent: September 30, 2003
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Akira Sugawara, Kazuki Hatakeyama, Le Ling
  • Patent number: 6627149
    Abstract: A high purity silver wire for use in recording, acoustic or image transmission applications. The high purity silver wire is made of high purity silver containing sulfur, iron, copper, palladium, gold and lead impurities in an amount such that no one of the sulfur, iron, copper, palladium, gold and lead impurities individually exceeds 0.5 ppmw, and wherein all other impurities are present in a total amount of less than 1 ppmw.
    Type: Grant
    Filed: January 11, 1999
    Date of Patent: September 30, 2003
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Kishio Tayama, Takashi Ohgami, Hiroshi Miura
  • Patent number: 6620344
    Abstract: Copper particle clusters constituting a powder suitable for making a conductive paste are provided that are individually composed of not fewer than two and not more than 20 unit particles joined through neck portions. A conductive paste made from the powder is excellent in conductivity. A conductive filler for conductive paste is provided that consists essentially of a mixture of copper particle clusters A individually composed of two or more unit particles joined through neck portions and spherical metallic particles B of smaller diameter than the particles A. A conductive paste made from the filler is low in viscosity and excellent in conductivity.
    Type: Grant
    Filed: December 21, 2000
    Date of Patent: September 16, 2003
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Kazushi Sano, Yoshihiro Okada, Hiromasa Miyoshi, Yoshiomi Takada
  • Patent number: 6613450
    Abstract: There is provided a metal/ceramic bonding article which ensures sufficient thermal shock resistance and has a substrate having a small outside dimension and which has both high reliability and compactness. The metal/ceramic bonding article comprises: a ceramic substrate; and a metal plate bonded to the ceramic substrate via a brazing filler metal, wherein the brazing filler metal protrudes from the bottom face of the metal plate by a length which is longer than 30 &mgr;m and which is 250 &mgr;m or less, or wherein the brazing filler metal protrudes from the bottom face of the metal plate by a length which is 25% or more of the thickness of the metal plate.
    Type: Grant
    Filed: March 27, 2002
    Date of Patent: September 2, 2003
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Nobuyoshi Tsukaguchi, Jyunji Nakamura, Masahiko Wada, Makoto Namioka, Masami Kimura
  • Publication number: 20030150293
    Abstract: A 99.99% pure indium feed is charged into crucible 8 and heated to 1250° C. by upper heater 6 in a vacuum atmosphere at 1×10−4 Torr, whereupon indium evaporates, condenses on the inner surfaces of inner tube 3 and drips to be recovered into liquid reservoir 9 in the lower part of tubular member 11 whereas impurity elements having lower vapor pressure than indium stay within crucible 8. The recovered indium mass in liquid reservoir 9 is heated to 1100° C. by lower heater 7 and the resulting vapors of impurity elements having higher vapor pressure than indium pass through diffuser plates 12 in the upper part of tubular member 11 to be discharged from the system whereas the indium vapor recondenses upon contact with diffuser plates 12 and returns to liquid reservoir 9, yielding 99.9999% pure indium while preventing the loss of indium.
    Type: Application
    Filed: January 2, 2003
    Publication date: August 14, 2003
    Applicant: DOWA MINING CO., LTD.
    Inventors: Kishio Tayama, Toshiaki Hodozuka
  • Publication number: 20030145683
    Abstract: A 99.99% pure indium feed is charged into crucible 8 and heated to 1250° C. by upper heater 6 in a vacuum atmosphere at 1×10−4 Torr, whereupon indium evaporates, condenses on the inner surfaces of inner tube 3 and drips to be recovered into liquid reservoir 9 in the lower part of tubular member 11 whereas impurity elements having lower vapor pressure than indium stay within crucible 8. The recovered indium mass in liquid reservoir 9 is heated to 1100° C. by lower heater 7 and the resulting vapors of impurity elements having higher vapor pressure than indium pass through diffuser plates 12 in the upper part of tubular member 11 to be discharged from the system whereas the indium vapor recondenses upon contact with diffuser plates 12 and returns to liquid reservoir 9, yielding 99.9999% pure indium while preventing the loss of indium.
    Type: Application
    Filed: January 30, 2002
    Publication date: August 7, 2003
    Applicant: DOWA MINING CO., LTD.
    Inventors: Kishio Tayama, Toshiaki Hodozuka
  • Publication number: 20030145684
    Abstract: In a purification apparatus comprising a vertical stack of a feed heating zone having the feed crucible 1, a condensation zone having a plurality of condensation vapor passage plates 5, a solidification zone having a solidification crucible 2 and an entrapment/solidification zone having a plurality of entrapment/solidification vapor passage plates 7, a feed metal, preferably with a purity of at least 3N, is charged into the feed crucible 1 in a vacuum atmosphere, preferably at no more than 13 Pa (10−1 Torr), with the feed crucible 1 and the condensation vapor passage plates 5 being heated at controlled temperatures to generate the vapor of the metal in the feed heating zone; part of the metal vapor is condensed to form a molten condensate which is returned into the feed crucible 1, thereby; the process solidifying the high-purity metal in the solidification zone; the solidified metal has a purity of at least 6N and contains Cl, F and S in a respective amount of no more than 0.
    Type: Application
    Filed: March 29, 2002
    Publication date: August 7, 2003
    Applicant: DOWA MINING CO., LTD.
    Inventors: Kishio Tayama, Shunichi Kimura
  • Publication number: 20030129076
    Abstract: Copper alloy having the basic composition Cu—Zn—Sn contains 23-28 wt % Zn and 0.3-1.8 wt % Sn and satisfies the relation 6.0≦0.25X+Y≦8.5 (where X is the addition of Zn in wt % and Y is the addition of Sn in wt %). The alloy is cast into an ingot by melting and cooling over the range from the liquidus line to 600° C. at a rate of at least 50° C./min; the ingot is hot rolled at a temperature not higher than 900° C. and then subjected to repeated cycles of cold rolling and annealing at 300-650° C. to control the size of crystal grains, thereby producing a rolled strip having a 0.2% yield strength of at least 600 N/mm2, a tensile strength of at least 650 N/mm2, an electrical conductivity of at least 20% IACS, a Young's modulus of no more than 120 kN/mm2 and a percent stress relaxation of no more than 20%.
    Type: Application
    Filed: September 23, 2002
    Publication date: July 10, 2003
    Applicant: DOWA MINING CO., LTD.
    Inventors: Akira Sugawara, Kazuki Hatakeyama, Le Ling
  • Patent number: 6589412
    Abstract: A sliding member having excellent seizure resistance comprising a metallic member provided with a sulfide-based solid lubricating layer on the sliding surface thereof is provided, characterized in that the interface of the metallic member in contact with said solid lubricating layer is provided with a surface roughness Rmax of 1 &mgr;m or higher. The sliding member above is obtained by preparing an aqueous solution dissolved therein one or two types or more of thiocyanates or thiosulfates of alkali metals or alkaline earth metals, and by performing electrolytic treatment in which a steel member the surface roughness thereof is controlled is used as the anode. In this manner, an iron sulfide based layer is formed on the surface of the steel member by using the Fe component derived from the steel and the S component from the solution as the reacting agents.
    Type: Grant
    Filed: October 10, 2000
    Date of Patent: July 8, 2003
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Osamu Ogawa, Motoyoshi Yamauchi, Toshiki Kasamatsu
  • Publication number: 20030096709
    Abstract: The present invention provides an oxide superconductor thick film which is formed on a substrate or a board and has a high Jc and Ic and a method for manufacturing the same. Predetermined amounts of materials containing elements of Bi, Pb, Sr, Ca and Cu are weighed, mixed and subjected to steps of calcining, milling, and drying, and thereafter an organic binder and an organic vehicle are added thereto to prepare a (Bi, Pb)2+aSr2Ca2Cu3Oz, superconductive paste, which is applied to the surface of a substrate or a board in a thickness of 260 &mgr;m or more and dried. Thereafter, the paste is first subjected to burning at temperatures of 835° C. to 840° C. for 100 hours, then pressurization, and further burning at temperatures of 835° C. to 840° C. for 100 hours, thereby preparing an oxide superconductor thick film having a film thickness of 130 &mgr;m or more having a high Jc and Ic.
    Type: Application
    Filed: August 26, 2002
    Publication date: May 22, 2003
    Applicant: DOWA MINING CO., LTD.
    Inventors: Masahiro Kojima, Masakazu Kawahara, Michiharu Ichikawa, Hiroyuki Kado, Masatoyo Shibuya
  • Publication number: 20030095887
    Abstract: Copper-base alloys are provided that maintain high hot forgeability and cuttability and low-cost feature and which still are improved in resistance to dezincification. The alloys comprise 57-69% of Cu, 0.3-3% of Sn and 0.02-1.5% of Si, all percentages based on weight, with a Si/Sn value in the range of 0.051, and the balance being Zn and incidental impurities.
    Type: Application
    Filed: November 22, 2002
    Publication date: May 22, 2003
    Applicant: DOWA MINING CO., LTD.
    Inventor: Shu-xin Dong
  • Patent number: 6533838
    Abstract: In a process for separating impurities from a raw gallium material containing impurities, a process for refining gallium comprising progressively solidifying a raw gallium material provided in a liquid state inside a vessel while applying stirring, such that the diameter of the tubular solidification boundary gradually advances from the inner wall plane of the vessel towards the center of the vessel to reduce the diameter of the tubular solidification boundary, and separating the liquid phase remaining in the central portion of the vessel from the solidified phase before the entire raw material inside the vessel is solidified. The process above is repeated as required by using, as the raw gallium material, the solidified phase from which the liquid phase is separated. A metallic gallium favorably used for the preparation of a compound semiconductor can be obtained by analyzing the impurity concentration of the impurity-concentrated Ga separated from the solidified layer.
    Type: Grant
    Filed: June 19, 2000
    Date of Patent: March 18, 2003
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Takeharu Yamamura, Hidekazu Kato, Takashi Ohgami, Kishio Tayama, Kanichi Okuda
  • Publication number: 20030041692
    Abstract: In one method, a zinc concentrate is leached as elemental sulfur and other by-products are stripped from the surfaces of the particles in the concentrate by means of a grinding machine such as a ball mill. The ferric ion consumed by leaching is regenerated for recycled use by introducing oxygen into the post-leaching solution flowing through feed pipes. This method can shorten the leach time by a substantial degree.
    Type: Application
    Filed: January 28, 2002
    Publication date: March 6, 2003
    Applicant: DOWA MINING CO., LTD.
    Inventors: Manabu Kanno, Yoshiyuki Watanabe, Kaoru Saruta, Akira Narumi
  • Publication number: 20030037434
    Abstract: A metal-ceramic circuit board is characterized by being constituted by bonding on a base plate of aluminum or aluminum alloy at least one of ceramic substrate boards having a conductive metal member for an electronic circuit. A method of manufacturing a metal-ceramic circuit board is characterized by comprising the steps of melting aluminum or aluminum alloy in a vacuum or inert gas atmosphere to form a molten metal, contacting one surface of a ceramic substrate board directly with the molten metal in a vacuum or inert gas atmosphere, cooling the molten metal and the ceramic substrate board to form a base plate of aluminum or aluminum alloy, which is bonded directly on the ceramic substrate board without forming any oxidizing film therebetween and bonding a conductive metal member for an electronic circuit on the ceramic substrate board by using a brazing material. The base plate has a proof stress not higher than 320 (MPa) and a thickness not smaller than 1 mm.
    Type: Application
    Filed: September 12, 2002
    Publication date: February 27, 2003
    Applicant: DOWA MINING CO., LTD.
    Inventors: Hideyo Osanai, Masahiro Furo
  • Publication number: 20030030036
    Abstract: To a hydrochloric acid solution containing In and Sn and which is held at 20° C., an alkali solution is added to adjust pH to 3; the temperature of the mixed solution is raised to 90° C. and the alkali solution is further added to adjust pH to 7.5. The resulting precipitate is recovered by filtration, dehydrated and dried to yield a Sn-containing In hydroxide; the hydroxide is put into a tubular furnace and fired in a nitrogen gas atmosphere containing water vapor and NH3 gas at 600°C. for 2 hours to produce a Sn-containing In oxide in the form of plates having a major axis of 0.041 &mgr;m, a minor axis of 0.025 &mgr;m and a major-to-minor axis ratio of 1.64.
    Type: Application
    Filed: March 28, 2002
    Publication date: February 13, 2003
    Applicant: DOWA MINING CO., LTD.
    Inventors: Tatsumi Inamura, Yoshio Moteki, Yoshichika Horikawa, Kohichiro Eshima
  • Publication number: 20030015062
    Abstract: A copper powder is provided that has an average particle diameter in the range of from not less than 0.1 &mgr;m to less than 1.5 &mgr;m, that has a narrow particle size distribution width whose value A defined by Equation (1) below in terms of X25, X50 and X75 defined below is not greater than 1.2, and that forms a pseudo-fused sintered product when held at a temperature of 800° C.
    Type: Application
    Filed: August 13, 2002
    Publication date: January 23, 2003
    Applicant: Dowa Mining Co., LTD
    Inventors: Kazushi Sano, Yoshihiro Okada, Hiromasa Miyoshi, Yoshiomi Takada
  • Publication number: 20030017396
    Abstract: A zinc alloy containing Al, Bi and In is reduced to particles by gas atomization and sieved to prepare a zinc alloy powder. A polyacrylic acid powder and a magnesium hydroxide powder are added to the zinc alloy powder and the ingredients are mixed to make an anode composition. Zinc oxide is added to an aqueous KOH solution to prepare a liquid electrolyte which is mixed with the anode composition under stirring to make a gelled anode composition that has improved performance in pulsed discharge to get large current without increasing the evolution of hydrogen gas.
    Type: Application
    Filed: June 11, 2002
    Publication date: January 23, 2003
    Applicant: DOWA MINING CO., LTD.
    Inventors: Kenichi Harigae, Masayuki Nishina
  • Patent number: 6506264
    Abstract: A ferromagnetic powder containing iron as the principal component and containing more than 5 to 50 at. % Co, 0.1 to 30 at. % Al, 0.1 to 10 at. % of a rare earth element inclusive of Y, 0.05% by weight or less of an element belonging to Group 1a of the Periodic Table, and 0.1% by weight or less (inclusive of 0% by weight) of an element belonging to Group 2a of the Periodic Table, the powder comprising flat acicular particles having a mean major axis length of 0.01 to 0.40 &mgr;m and a crystallite diameter as determined by X-ray diffraction (Dx) of 50 to 250 angstrom, provided that the cross section diameter in the minor axis direction cut perpendicular to the major axis has a larger width and a smaller width, and that this cross section ratio in the minor axis direction, which is a larger width to smaller width ratio, uniformly yields a value of greater than 1, preferably 1.5 or higher, and the powder yielding a &sgr;s/Dx ratio of 0.
    Type: Grant
    Filed: August 10, 2000
    Date of Patent: January 14, 2003
    Assignee: Dowa Mining Co., Ltd.
    Inventors: Seiichi Hisano, Kazuhisa Saito, Kazushi Sano, Akio Sawabe, Akito Inoue, Kenichi Inoue
  • Publication number: 20020189322
    Abstract: A vacuum heat treatment furnace comprising a furnace shell, a casing arranged in an inner side of the furnace shell, a heat insulating layer consisting of a thick plate-like alumina-silica series ceramic fiber blanket and a thin plate-like alumina series ceramic material arranged in an inside of the casing, and a heater arranged in a heating room surrounded by the heat insulating layer.
    Type: Application
    Filed: March 28, 2002
    Publication date: December 19, 2002
    Applicant: Dowa Mining Co., Ltd.
    Inventors: Hidetoshi Juryozawa, Keiji Yokose, Fumitaka Abukawa, Jun Takahashi, Hisashi Ebihara