Method of texturing magnetic hard disk substrate

Abstract

Texturing marks are formed on the surface of a substrate of a magnetic hard disk first by forming approximately concentric circular preliminary marks in a first step and then forming in a second step approximately concentric circular texturing marks on the surface of the substrate based on the preliminary marks formed in the first step. The surface after the texturing marks are formed in the second step has average surface roughness in the range of 1 Å or more and 6 Å or less and a ratio of maximum surface roughness to the average surface roughness in the range of less than 10. A foamed tape and a lubricant not containing any abrading particles are used in the second step. The foamed tape has a foamed layer having average diameter of air bubbles in the range of 1 μm or more and 50 μm or less, compressibility in the range of 3% or more and 7% or less, compression recovery ratio in the range of 40% or more and 60% or less, Shore D hardness in the range of 20 degrees or more and 30 degrees or less, and thickness in the range of 50 μm or more and 80 μm or less.

1 . A texturing method for forming texturing marks on the surface of a substrate of a magnetic hard disk, said method comprising: 
 a first step of forming approximately concentric circular preliminary marks on the surface of said substrate; and    a second step of forming approximately concentric circular texturing marks on said surface of said substrate based on said preliminary marks, wherein said surface after said texturing marks are formed in said second step has average surface roughness in the range of 1 Å or more and 6 Å or less and a ratio of maximum surface roughness to said average surface roughness in the range of less than 10;    wherein said first step comprises the steps of rotating said substrate, supplying slurry having abrading particles dispersed to the surface of said substrate and pressing a woven or non-woven cloth tape to the surface of said substrate;    wherein said second step comprises the steps of rotating said substrate, supplying a lubricant to the surface of said substrate with said preliminary marks formed thereon, and pressing a foamed tape on the surface of said substrate;    wherein said foamed tape comprises a base material formed as a tape, and a foamed layer formed on the surface of said base material; and    wherein said foamed layer has average diameter of air bubbles in the range of 1 μm or more and 50 μm or less, compressibility in the range of 3% or more and 7% or less, compression recovery ratio in the range of 40% or more and 60% or less and Shore D hardness in the range of 20 degrees or more and 30 degrees or less.    
   
   
       2 . The texturing method of  claim 1  wherein said foamed layer has average diameter of air bubbles in the range of 1 μm or more and 30 μm or less.  
   
   
       3 . The texturing method of  claim 1  wherein said foamed layer comprises polyurethane resin.  
   
   
       4 . The texturing method of  claim 1  wherein said first step further includes the step of washing the surface of said substrate after the step of forming said approximately concentric circular marks.  
   
   
       5 . The texturing method of  claim 1  wherein said second step further includes the step of washing the surface of said substrate after the step of forming said approximately concentric circular texturing marks.