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AssigneesFurukawa Electric Co., Ltd., Uacj Corporation
InventorsHideyuki HATAKEYAMA, Koichiro TAKIGUCHI
Estimating the term…
The present invention intends to provide a substrate for a magnetic disk and a method for manufacturing same, and a magnetic disk capable of holding high flatness after long-term use despite being thin, coping with a high capacity of hard disk, and improving long-term reliability thereof. In the substrate according to the present invention, when a process for heating a substrate at 120° C. for 30 minutes and then cooling the substrate at −40° C. for 30 minutes is defined as one cycle, the flatness PV of a surface of the substrate measured at 25° C. after a thermal impact test in which the cycle is repeatedly performed 200 times is not more than 12 μm. The present invention further encompasses a magnetic disk having a similar flatness PV under the same conditions. The present invention still further encompasses a method for manufacturing the substrate for a magnetic disk.
A substrate for a magnetic disk, having
A magnetic disk, having a planar level PV of 12 μm or less measured at 25° C. on a surface of the magnetic disk after a thermal shock test, the thermal shock test performed by repeating a cycle of heating the magnetic disk at 120° C. for 30 minutes and subsequently cooling the magnetic disk at −40° C. for 30 minutes 200 times.
Dependencies are inferred from the claim text.