Glass substrate for flat panel display

Abstract

A flat panel display glass substrate includes a glass comprising, in mol %, 55-80% SiO 2 , 3-20% Al 2 O 3 , 3-15% B 2 O 3 , and 3-25% RO (the total amount of MgO, CaO, SrO, and BaO). The contents in mol % of SiO 2 , Al 2 O 3 , and B 2 O 3 satisfy a relationship (SiO 2 +Al 2 O 3 )/(B 2 O 3 )=7.5-17. The strain point of the glass is 665° C. or more. The devitrification temperature of the glass is 1250° C. or less. The substrate has a heat shrinkage rate of 75 ppm or less. The rate of heat shrinkage is calculated from the amount of shrinkage of the substrate measured after a heat treatment which is performed at a rising and falling temperature rate of 10° C./min and at 550° C. for 2 hours by the rate of heat shrinkage (ppm)={the amount of shrinkage of the substrate after the heat treatment/the length of the substrate before the heat treatment}×10 6 .

What is claimed is: 
     
         1 . A flat panel display glass substrate on which a p-Si TFT can be formed, the flat panel display glass substrate comprising a glass comprising, as expressed in mol %:
 55-80% SiO 2 ;   3-20% Al 2 O 3 ;   3-15% B 2 O 3 ; and   3-25% RO, where RO represents the total amount of MgO, CaO, SrO, and BaO, wherein   in the glass, the contents in mol % of SiO 2 , Al 2 O 3 , and B 2 O 3  satisfy a relationship (SiO 2 +Al 2 O 3 )/(B 2 O 3 )=7.5-17,   the strain point of the glass is 665° C. or more,   the devitrification temperature of the glass is 1250° C. or less,   the glass substrate has a rate of heat shrinkage of 75 ppm or less, and   the rate of heat shrinkage is calculated from the amount of shrinkage of the glass substrate measured after a heat treatment which is performed at a rising and falling temperature rate of 10° C./min and at 550° C. for 2 hours by;
   the rate of heat shrinkage (ppm)={the amount of shrinkage of the glass substrate after the heat treatment/the length of the glass substrate before the heat treatment}×10 6 .
 
   
     
     
         2 . A flat panel display glass substrate on which a p-Si TFT can be formed, the flat panel display glass substrate comprising a glass comprising, as expressed in mol %;
 55-80% SiO 2 ;   3-20% Al 2 O 3 ;   3-15% B 2 O 3 ; and   3-25% RO, where RO represents the total amount of MgO, CaO, SrO, and BaO, wherein   in the glass the contents in mol % of SiO 2 , Al 2 O 3 , and B 2 O 3  satisfy a relationship (SiO 2 +Al 2 O 3 )/(B 2 O 3 )=8.45-17.0,   the devitrification temperature of the glass is 1250° C. or less,   the glass substrate has a rate of heat shrinkage of 60 ppm or less, and   the rate of heat shrinkage is calculated from the amount of shrinkage of the glass substrate measured after a heat treatment which is performed at a rising and falling temperature rate of 10° C./min and at 550° C. for 2 hours by:
   the rate of heat shrinkage (ppm)={the amount of shrinkage of the glass substrate after the heat treatment/the length of the glass substrate before the heat treatment}×10 6 .
 
   
     
     
         3 . The flat panel display glass substrate according to  claim 1 , wherein
 the glass contains, as expressed in mol %,
 0-5% ZnO, 
   in the glass, the contents in mol % of SiO 2  and Al 2 O 3  satisfy SiO 2 +Al 2 O 3 ≧75%, and   the contents in mol % of RO, ZnO, and B 2 O 3  satisfy RO+ZnO+B 2 O 3 =7-25%.   
     
     
         4 . The flat panel display glass substrate according to  claim 2 , wherein
 the glass comprises, as expressed in mol %,
 0-5% ZnO, 
   in the glass, the contents in mol % of SiO 2  and Al 2 O 3  satisfy SiO 2 +Al 2 O 3 ≧75%, and   the contents in mol % of RO, ZnO, and B 2 O 3  satisfy RO+ZnO+B 2 O 3 =7-25%.   
     
     
         5 . The flat panel display glass substrate according to  claim 1 , wherein
 in the glass, the sum of the MgO, CaO, SrO, and BaO contents is 4-20 mol %.   
     
     
         6 . The flat panel display glass substrate according to  claim 2 , wherein
 in the glass, the sum of the MgO, CaO, SrO, and BaO contents is 4-20 mol %.   
     
     
         7 . The flat panel display glass substrate according to  claim 1 , wherein
 in the glass, the ratio of the CaO content to the sum of the MgO, CaO, SrO, and BaO contents in mol % is more than 0.5.   
     
     
         8 . The flat panel display glass substrate according to  claim 2 , wherein
 in the glass, the ratio of the CaO content to the sum of the MgO, CaO, SrO, and BaO contents in mol % is more than 0.5.   
     
     
         9 . The flat panel display glass substrate according to  claim 1 , wherein
 the liquidus viscosity of the glass is 10 4.5  dPa·s or more, and the flat panel display glass substrate is obtained by forming the glass using a downdraw process.   
     
     
         10 . The flat panel display glass substrate according to  claim 2 , wherein
 the liquidus viscosity of the glass is 10 4.5  dPa·s or more, and the flat panel display glass substrate is obtained by forming the glass using a downdraw process.   
     
     
         11 . The flat panel display glass substrate according to  claim 1 , wherein
 the glass comprises substantially no As 2 O 3  or Sb 2 O 3 .   
     
     
         12 . The flat panel display glass substrate according to  claim 2 , wherein
 the glass comprises substantially no As 2 O 3  or Sb 2 O 3 .   
     
     
         13 . The flat panel display glass substrate according to  claim 1 , wherein
 the flat panel display glass substrate is a liquid crystal display glass substrate.   
     
     
         14 . The flat panel display glass substrate according to  claim 2 , wherein
 the flat panel display glass substrate is a liquid crystal display glass substrate.   
     
     
         15 . A flat panel display glass substrate comprising a glass comprising, as expressed in mol %:
 55-80% SiO 2 ;   3-20% Al 2 O 3 ;   3-15% B 2 O 3 ; and   3-25% RO, where RO represents the total amount of MgO, CaO, SrO, and BaO,   wherein   in the glass, the contents in mol % of SiO 2 , Al 2 O 3 , and B 2 O 3  satisfy a relationship (SiO 2 +Al 2 O 3 )/(B 2 O 3 )=7.5-17,   the strain point of the glass is 665° C. or more,   the devitrification temperature of the glass is 1250° C. or less,   the glass substrate has a rate of heat shrinkage of 75 ppm or less, and   the rate of heat shrinkage is calculated from the amount of shrinkage of the glass substrate measured after a heat treatment which is performed at a rising and falling temperature rate of 10° C./min and at 550° C. for 2 hours by:
   the rate of heat shrinkage (ppm)={the amount of shrinkage of the glass substrate after the heat treatment/the length of the glass substrate before the heat treatment}×10 6 .
 
   
     
     
         16 . A flat panel display glass substrate comprising a glass comprising, as expressed in mol %:
 55-80% SiO 2 ;   3-20% Al 2 O 3 ;   3-15% B 2 O 3 ; and   3-25% RO, where RO represents the total amount of MgO, CaO, SrO, and BaO,   wherein   in the glass, the contents in mol % of SiO 2 , Al 2 O 3 , and B 2 O 3  satisfy a relationship (SiO 2 +Al 2 O 3 )/(B 2 O 3 )=8.45-17.0,   the devitrification temperature of the glass is 1250° C. or less,   the glass substrate has a rate of heat shrinkage of 60 ppm or less, and   the rate of heat shrinkage is calculated from the amount of shrinkage of the glass substrate measured after a heat treatment which is performed at a rising and falling temperature rate of 10° C./min and at 550° C. for 2 hours by:
   the rate of heat shrinkage (ppm)={the amount of shrinkage of the glass substrate after the heat treatment/the length of the glass substrate before the heat treatment}×10 6 .
 
   
     
     
         17 . A flat panel display glass substrate on which a p-Si TFT can be formed, the flat panel display glass substrate comprising a glass comprising, as expressed in mol %:
 55-80% SiO 2 ;   3-20% Al 2 O 3 ;   3-15% B 2 O 3 ; and   3-25% RO, where RO represents the total amount of MgO, CaO, SrO, and BaO,   wherein   in the glass, the contents in mol % of SiO 2 , Al 2 O 3 , and B 2 O 3  satisfy a relationship (SiO 2 +Al 2 O 3 )/(B 2 O 3 )=7.5-17,   the strain point of the glass is 665° C. or more,   the devitrification temperature of the glass is 1250° C. or less, and   the glass substrate has a rate of heat shrinkage of 75 ppm or less after a heat treatment in which the glass substrate is kept at Tg for 30 min, then cooled at a rate of 100° C./min until the temperature thereof reaches Tg−100° C., then cooled until the temperature reaches room temperature, and then kept at 550° C. for 2 hours, wherein a rising and falling temperature rate is 10° C./min.