# US 2019/0378540 A1 · Magnetic recording medium > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0378540 A1 - Document ID: US20190378540A1 - Status: Published application - Kind: A1 - Application number: 16/463,520 - Filed: 2018-11-08 - Published: 2019-12-12 - Earliest claimed: 2017-11-08 - Assignees: Sony Corporation - Applicants: Sony Corporation - Inventors: Noboru SEKIGUCHI; Minoru YAMAGA - Web page: https://patentgrep.com/patent/US20190378540A1 ## CPC - C23C 14/205: {by cathodic sputtering} - G11B 5/62: Record carriers characterised by the selection of the material - C23C 14/0021: {Reactive sputtering or evaporation} - C23C 14/545: {using measurement on deposited material} - C23C 14/56: Apparatus specially adapted for continuous coating; Arrangements for maintaining the vacuum, e.g. vacuum locks - C23C 14/562: {for coating elongated substrates} - G11B 5/59688: {Servo signal format patterns or signal processing thereof, e.g. dual, tri, quad, burst signal patterns} - G11B 5/68: comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent - G11B 5/70: on a base layer - G11B 5/70642: {iron oxides} - G11B 5/70678: {Ferrites} - G11B 5/733: characterised by the addition of non-magnetic particles {(base layers having a non-magnetic layer under a soft magnetic layer G11B5/736; magnetic recording media substrates G11B5/739)} - G11B 5/735: characterised by the back layer {(magnetic recording media substrates G11B5/739)} - G11B 5/7358: {specially adapted for achieving a specific property, e.g. average roughness [Ra]} - C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04) - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract The average thickness tT of a magnetic recording medium meets the requirement that tT ≤5.5 [μm], and the dimensional change amount Δw in the width direction of the magnetic recording medium with respect to the tension change in the longitudinal direction of the magnetic recording medium meets the requirement that 700 ppm/N≤Δw. ## Claims ### Claim 1 A magnetic recording medium, wherein an average thickness tT meets the requirement that tT≤5.5 [μm], and a dimensional change amount Δw in a width direction with respect to a tension change in a longitudinal direction meets the requirement that 700 [ppm/N]≤Δw. ### Claim 2 (depends on 1) The magnetic recording medium according to claim 1, wherein the dimensional change amount Δw meets the requirement that 750 [ppm/N]≤Δw. ### Claim 3 (depends on 1) The magnetic recording medium according to claim 1, wherein the dimensional change amount Δw meets the requirement that 800 [ppm/N]≤Δw. ### Claim 4 (depends on 1) The magnetic recording medium according to claim 1, wherein a temperature expansion coefficient α meets the requirement that 6 [ppm/° C.]≤α≤8 [ppm/° C.], and a humidity expansion coefficient β meets the requirement that β≤5 [ppm /% RH]. ### Claim 5 (depends on 1) The magnetic recording medium according to claim 1, wherein a Poisson's ratio ρ meets the requirement that 0.3≤ρ. ### Claim 6 (depends on 1) The magnetic recording medium according to claim 1, wherein an elastic limit value σMD in the longitudinal direction meets the requirement that 0.8 [N]≤σMD. ### Claim 7 (depends on 6) The magnetic recording medium according to claim 6, wherein the elastic limit value σMD is independent of a speed V for elastic limit measurement. ### Claim 8 (depends on 1) The magnetic recording medium according to claim 1, further comprising a recording layer that is a sputtered layer. ### Claim 9 (depends on 8) The magnetic recording medium according to claim 8, wherein an average thickness tm of the recording layer meets the requirement that 9 [nm]≤tm≤90 [nm]. ### Claim 10 (depends on 1) The magnetic recording medium according to claim 1, further comprising a vertically oriented recording layer. ### Claim 11 (depends on 1) The magnetic recording medium according to claim 1, further comprising a recording layer comprising magnetic powder. ### Claim 12 (depends on 11) The magnetic recording medium according to claim 11, wherein an average thickness tm of the recording layer meets the requirement that 35 [nm]≤tm≤90 [nm]. ### Claim 13 (depends on 11) The magnetic recording medium according to claim 11, wherein the magnetic powder comprises an ϵ-iron oxide magnetic powder, a barium ferrite magnetic powder, or a cobalt ferrite magnetic powder. ### Claim 14 (depends on 1) The magnetic recording medium according to claim 1, further comprising a back layer, wherein an average thickness tb of the back layer meets the requirement that tb≤0.6 [μm]. ### Claim 15 (depends on 1) The magnetic recording medium according to claim 1, further comprising a back layer, wherein surface roughness Rb of the back layer meets the requirement that Rb≤6.0 [nm]. ### Claim 16 (depends on 1) The magnetic recording medium according to claim 1, further comprising a magnetic surface and a back surface opposite to the magnetic surface, wherein an interlayer friction coefficient μ between the magnetic surface and the back surface meets the requirement that 0.20≤μ≤0.80. ### Claim 17 (depends on 1) The magnetic recording medium according to claim 1, wherein a squareness ratio in a vertical direction is 65% or more.