Magnetic disc drive, helium gas filled container, and apparatus

Abstract

A magnetic disk drive includes a base having an opening, a cover configured to close the opening of the base, and a pressure-sensitive adhesive sheet configured to seal a gap between the base and the cover. The pressure-sensitive adhesive sheet includes a pressure-sensitive adhesive layer, and a substrate layer configured to support the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer has a storage modulus of 250 kPa or less at 23° C. The substrate layer has an elastic modulus of 1,680 N/cm to 3,000 N/cm. The pressure-sensitive adhesive sheet shows a deviation amount less than 1.0 mm, the amount being the deviation amount of the pressure-sensitive adhesive sheet per 250 gf/cm 2 of the sheet in a holding ability test at 80° C. after one hour from a time when the holding ability test is started. Helium gas is accommodated in a cavity defined by the base and the cover.

1 . A magnetic disk drive comprising:
 a base having at least one sidewall defining an opening;   a cover configured to close the opening of the base; and   a pressure-sensitive adhesive sheet configured to seal a gap between the base and the cover, the pressure-sensitive adhesive sheet comprising:
 a pressure-sensitive adhesive layer; and 
 a substrate layer configured to support the pressure-sensitive adhesive layer, 
   
       wherein
 the pressure-sensitive adhesive layer has a storage modulus of 250 kPa or less at 23° C., 
 the substrate layer has an elastic modulus of 1,680 N/cm to 3,000 N/cm, 
 the pressure-sensitive adhesive sheet shows a deviation amount less than 1.0 mm, the amount being the deviation amount of the pressure-sensitive adhesive sheet per 250 gf/cm 2  of the sheet in a holding ability test at 80° C. after one hour from a time when the holding ability test is started, and 
 helium gas is accommodated in a cavity defined by the base and the cover. 
 
     
     
         2 . The magnetic disk drive according to  claim 1 , wherein the helium gas accommodated in the cavity is filled at a pressure of 3,000 Pa. 
     
     
         3 . The magnetic disk drive according to  claim 2 , wherein the pressure-sensitive adhesive sheet seals the gap between the base and the cover such that a proportion of the helium gas accommodated in the cavity which leaks from the inner area to a 1 Pa environment is less than 1×10 −9  Pa·m 3 /s. 
     
     
         4 . The magnetic disk drive according to  claim 1 , wherein the at least one sidewall of the base or the cover comprises at least one through-hole, and the pressure-sensitive adhesive sheet seals the at least one through-hole. 
     
     
         5 . The magnetic disk drive according to  claim 1 , wherein a surface of the base and the cover has an arithmetic average roughness (Ra) of 0.5 μm or less and having a ten-point average roughness (Rz) of 7 μm or less. 
     
     
         6 . The magnetic disk drive according to  claim 1 , wherein one or more of the base or the cover comprises one or more of a metal, an alloy, a metal-covered surface, or an alloy-covered surface. 
     
     
         7 . The magnetic disk drive according to  claim 1 , wherein the pressure-sensitive adhesive layer has a probe tack of 20 kN/m 2  or more at 23° C. 
     
     
         8 . The magnetic disk drive according to  claim 1 , wherein the pressure-sensitive adhesive layer has a storage modulus of 12 kPa or more at 23° C. 
     
     
         9 . The magnetic disk drive according to  claim 1 , wherein the pressure-sensitive adhesive layer has a thickness of 15 μm or more. 
     
     
         10 . The magnetic disk drive according to  claim 1 , wherein the pressure-sensitive adhesive layer has a thickness of 200 μm or less. 
     
     
         11 . The magnetic disk drive according to  claim 1 , wherein the pressure-sensitive adhesive layer has a surface tension of 20 dyn/cm or more. 
     
     
         12 . The magnetic disk drive according to  claim 1 , wherein the pressure-sensitive adhesive layer has a surface tension of 60 dyn/cm or less. 
     
     
         13 . The magnetic disk drive according to  claim 1 , wherein the substrate layer has a thickness of 10 μm to 100 μm. 
     
     
         14 . The magnetic disk drive according to  claim 13 , wherein the substrate layer comprises aluminum. 
     
     
         15 . The magnetic disk drive according to  claim 1 , wherein a peel distance of the pressure-sensitive adhesive sheet is less than 50 mm, the peel distance being the peel distance of the sheet in a 100-g-constant-load peeling test at 23° C. after 24 hours from a time when the 100-g-constant-load peeling test is started. 
     
     
         16 . The magnetic disk drive according to  claim 1 , wherein the pressure-sensitive adhesive layer has a 180°-peel pressure-sensitive adhesive force of 5 N/20 mm or more from a stainless steel plate. 
     
     
         17 . The magnetic disk drive according to  claim 1 , wherein the pressure-sensitive adhesive layer includes a base material comprising one or more of an acrylic polymer, an ester polymer, or a rubber polymer. 
     
     
         18 . The magnetic disk drive according to  claim 17 , wherein the pressure-sensitive adhesive layer comprises at least one cross-linking agent in an amount of 1.5 parts by mass to 4.0 parts by mass, based on a 100 parts by mass total of the base material and the cross-linking agent included in the pressure-sensitive adhesive layer. 
     
     
         19 . A helium gas filled container, comprising:
 a body having a cavity defined therein and an opening through which the cavity is exposed;   a cover over the opening, the cover having at least one surface facing the cavity; and   a pressure-sensitive adhesive sheet over the opening, and between the body and the cover, such that the cavity is sealed by the cover and the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet comprising:
 a pressure-sensitive adhesive layer comprising a polymer; and 
 a substrate layer comprising a metal foil, 
   
       wherein
 the pressure-sensitive adhesive layer has a storage modulus of 250 kPa or less at 23° C., 
 the substrate layer has an elastic modulus of 1,680 N/cm to 3,000 N/cm and a thickness from 20 μm to 50 μm, and 
 helium gas is accommodated in the cavity sealed by the base, the cover and the pressure-sensitive adhesive sheet. 
 
     
     
         20 . An apparatus, comprising:
 a housing having a cavity defined therein and an opening through which the cavity is exposed;   a cover substantially closing the opening; and   a pressure-sensitive adhesive sheet between the body and the cover such that the cavity is sealed by the cover and the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet comprising:
 a pressure-sensitive adhesive layer comprising at least one polymer and at least one cross-linking agent; and 
 a substrate layer comprising a metal, 
   
       wherein
 the at least one cross-linking agent is in an amount of 1.5 parts by mass to 4.0 parts by mass, based on a 100 parts by mass total of the at least one polymer and the cross-linking agent included in the pressure-sensitive adhesive layer, 
 the pressure-sensitive adhesive layer has a storage modulus of 250 kPa or less at 23° C., 
 the substrate layer has an elastic modulus of 1,680 N/cm to 3,000 N/cm and a thickness from 10 μm to 50 μm, 
 helium gas is accommodated in the cavity at a pressure of 3,000 Pa, and 
 the pressure-sensitive adhesive sheet seals the cavity such that a proportion of the helium gas accommodated in the cavity which leaks from the inner area to a 1 Pa environment is less than 1×10 −9  Pa·m 3 /s.