Coating processes – Magnetic base or coating – Magnetic coating
Reexamination Certificate
2007-07-03
2007-07-03
Chaney, Carol (Department: 1773)
Coating processes
Magnetic base or coating
Magnetic coating
C427S130000, C427S131000, C428S831000, C428S832000
Reexamination Certificate
active
11181109
ABSTRACT:
Proposed are a substrate that comprises an easily producible soft magnetic backing film and can reduce spike noise from the soft magnetic backing film, and a method for producing the substrate. More specifically, provided are a substrate for a perpendicular magnetic recording hard disk medium, comprising an Si single crystal substrate (1) having a diameter of 65 mm or less, a thickness of 1 mm or less and an average surface roughness (Rms) of 1 nm or more and 1000 nm or less; an under-plated layer (2) formed on the substrate, the layer (2) comprising one or more metals selected from a group consisting of Ni, Cu and Ag and having a thickness of 1 nm to 300 nm; and a plated soft magnetic layer (3) formed on the under-plated layer, the layer (3) having a thickness of 50 nm or more and less than 1000 nm, a coercivity of 20 Oe(oersteds) or less and a saturation magnetization of 1T or more, wherein the average surface roughness (Rms) of the plated soft magnetic layer is 0.1 nm or more and 5 nm or less.
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Chaney Carol
de Falasco Louis
Myers Bigel Sibley & Sajovec P.A.
Shin-Etsu Chemical Co. , Ltd.
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