# US 2022/0037066 A1 · Metal magnetic powder and method for manufacturing same, as well as coil component and circuit board > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2022/0037066 A1 - Document ID: US20220037066A1 - Status: Published application - Kind: A1 - Application number: 17/370,765 - Filed: 2021-07-08 - Published: 2022-02-03 - Earliest claimed: 2020-07-31 - Assignees: Taiyo Yuden Co., Ltd. - Applicants: Taiyo Yuden Co., Ltd. - Inventors: Yoko ORIMO - Web page: https://patentgrep.com/patent/US20220037066A1 ## CPC - H01F 1/147: Alloys characterised by their composition {(treatment thereof for enhancing their electromagnetic properties C21D8/12)} - B22F 1/06: Metallic powder characterised by the shape of the particles (nanosized particles B22F1/054) - B22F 1/142: Thermal or thermo-mechanical treatment - B22F 1/145: Chemical treatment, e.g. passivation or decarburisation - B22F 1/16: Metallic particles coated with a non-metal (coated with lubricating or binding agents or with organic material B22F1/10) - C22C 38/34: with more than 1.5% by weight of silicon - H01F 1/33: mixtures of metallic and non-metallic particles; metallic particles having oxide skin - H01F 27/255: made from particles (H01F27/26 takes precedence) - H01F 41/0246: {Manufacturing of magnetic circuits by moulding or by pressing powder (magnetic cores made by moulding or by pressing powder H01F27/255; soft magnetic particles H01F1/20, H01F1/36)} - B22F 2301/35: Iron - B22F 2302/25: Oxide - B22F 2998/10: Processes characterised by the sequence of their steps - C22C 2202/02: Magnetic - H01F 1/26: by macromolecular organic substances - H01F 2017/048: {with encapsulating core, e.g. made of resin and magnetic powder} - Y10T 428/32: Composite [nonstructural laminate] of inorganic material having metal-compound-containing layer and having defined magnetic layer - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER - C22C: ALLOYS (treatment of alloys C21D, C22F) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A metal magnetic powder is constituted by metal magnetic grains that each include: a metal phase where the percentage of Fe at its center part is 98 percent by mass or higher, while the mass percentage of Fe at its contour part is lower than that at the center part; and an oxide film covering the metal phase, so as to inhibit oxidation of Fe contained in the metal phase, despite the high content percentage of Fe in the metal phase. ## Claims ### Claim 1 A metal magnetic powder constituted by metal magnetic grains, each comprising: a metal phase where a percentage of Fe at its center part is 98 percent by mass or higher, and a mass percentage of Fe at its contour part is lower than that at the center part; and an oxide film covering the metal phase. ### Claim 2 (depends on 1) The metal magnetic powder according to claim 1, wherein the percentage of Fe at the contour part is lower by 1 to 20 percent by mass than that at the center part. ### Claim 3 (depends on 1) The metal magnetic powder according to claim 1, wherein the percentage of Fe at the contour part is lower by 5 to 18 percent by mass than that at the center part. ### Claim 4 (depends on 1) The metal magnetic powder according to claim 1, wherein the percentage of Fe at the contour part is 80 to 85 percent by mass. ### Claim 5 (depends on 1) The metal magnetic powder according to claim 1, wherein the metal phase further contains at least one type of element selected from Si, Cr, Al, Ti, Zr, and Mg. ### Claim 6 (depends on 5) The metal magnetic powder according to claim 5, wherein a total of percentages of Si, Cr, Al, Ti, Zr, and Mg at the contour part is higher by at least 5 percent by mass than a total of corresponding percentages at the center part. ### Claim 7 (depends on 5) The metal magnetic powder according to claim 5, wherein a part containing more Fe than a total of mass percentages of Si, Cr, Al, Ti, Zr, and Mg is formed in the oxide film. ### Claim 8 A method for manufacturing a metal magnetic powder, including: preparing a material powder for metal magnetic material whose Fe content is 90 to 99 percent by mass and which contains at least one type of element that oxidizes more easily than Fe; placing the material powder in an atmosphere of 5 to 10 ppm in oxygen concentration and raising its temperature to 850° C. at a rate of rise in temperature of 100° C./min or higher; and heat-treating the material powder in the atmosphere at a temperature of 850° C. or above but below 1000° C. for 5 to 10 minutes. ### Claim 9 (depends on 1) A coil component, comprising: a magnetic body in which metal magnetic grains constituting the metal magnetic powder according to claim 1 are joined together via a resin or oxide; and conductors placed inside, or on a surface of, the magnetic body. ### Claim 10 (depends on 9) A circuit board on which the coil component according to claim 9 is installed.