Chemically-strengthened thin glass substrates new paradigms for modified curvature and methods of manufacture

A method of producing a chemically-strengthened glass substrate, which comprises the following steps:

• obtaining a chemically-strengthened glass substrate containing original host alkali ions having an average ionic radius in its chemical structure, the substrate having surface regions which have been subjected to ion-exchange by invasive alkali ions having an average ionic radius larger than the average ionic radius of the host alkali ions thereby building compressive stress therein;
• said chemically strengthened glass substrate having compressive stress which is asymmetric between a treatment-advantaged surface region and an opposing treatment-disadvantaged surface region, and wherein said asymmetric compressive stress between opposing surface regions causes undesired curvature to the glass substrate;
• providing a reverse ion-exchange medium which contains alkali ions having an average ionic radius that is smaller than the average ionic radius of the invasive ions;
• and
• (1) presenting the reverse ion-exchange medium to only a treatment-advantaged surface region within at least an area of the opposing surface regions and conducting reverse ion-exchange while presenting the reverse ion-exchange medium to lessen the compressive stress in said surface region relative to the treatment disadvantaged surface region opposing and thereby produce a chemically-strengthened substrate having less curvature than is present in the chemically-strengthened glass substrate prior to reverse ion-exchange, or
• (2) presenting the reverse ion-exchange medium to only one of a treatment-advantaged surface region or a treatment-disadvantaged surface region within at least an area of the opposing surface regions and conducting reverse ion-exchange while presenting the reverse ion-exchange medium to lessen the compressive stress in said surface region relative to the surface region opposing and thereby produce a chemically-strengthened substrate having a predetermined profile of curvature which is not present in the chemically-strengthened glass substrate prior to reverse ion-exchange,
• wherein the reverse ion-exchange medium is an aqueous salt solution which is dried so as to coat a surface region of the glass substrate with a salt compound which contains reversing alkali ions.

A chemically-strengthened glass article, which is produced by a process comprising the following steps:

• obtaining a chemically-strengthened glass substrate containing original host alkali ions having an average ionic radius in its chemical structure, the substrate having surface regions which have been subjected to ion-exchange by invasive alkali ions having an average ionic radius larger than the average ionic radius of the host alkali ions thereby building compressive stress therein;
• said chemically strengthened glass substrate having compressive stress which is asymmetric between a treatment-advantaged surface region and an opposing treatment-disadvantaged surface region, and wherein said asymmetric compressive stress between opposing surface regions causes undesired curvature to the glass substrate;
• providing a reverse ion-exchange medium which contains alkali ions having an average ionic radius that is smaller than the average ionic radius of the invasive ions;
• and
• (1) presenting the reverse ion-exchange medium to only a treatment-advantaged surface region within at least an area of the opposing surface regions and conducting reverse ion-exchange while presenting the reverse ion-exchange medium to lessen the compressive stress in said surface region relative to the treatment disadvantaged surface region opposing and thereby produce a chemically-strengthened substrate having less curvature than is present in the chemically-strengthened glass substrate prior to reverse ion-exchange, or
• (2) presenting the reverse ion-exchange medium to only one of a treatment-advantaged surface region or a treatment-disadvantaged surface region within at least an area of the opposing surface regions and conducting reverse ion-exchange while presenting the reverse ion-exchange medium to lessen the compressive stress in said surface region relative to the surface region opposing and thereby produce a chemically-strengthened substrate having a predetermined profile of curvature which is not present in the chemically-strengthened glass substrate prior to reverse ion-exchange.

A chemically-strengthened glass article, which is produced by a process comprising the following steps:

• providing a glass substrate having a chemical structure which contains host alkali ions having an average ionic radius situated in the surface regions thereof,
• presenting an ion-exchange medium which contains invasive alkali ions having an average ionic radius larger than the average ionic radius of the host alkali ions to surface regions of the substrate;
• and
• conducting ion-exchange while presenting the ion-exchange medium to the glass surface regions, thereby building compressive stress in the ion-exchanged surface regions and producing a chemically-strengthened glass substrate;
• said chemically-strengthened glass substrate having compressive stress which is asymmetric between a treatment-advantaged surface region and an opposing treatment disadvantaged surface region, and wherein said asymmetric compressive stress between opposing surface regions causes undesired curvature to the glass substrate;
• providing a reverse ion-exchange medium which contains alkali ions having an average ionic radius that is smaller than the average ionic radius of the invasive ions contained in the ion-exchange medium;
• and
• (1) presenting the reverse ion-exchange medium to only a treatment-advantaged surface region within at least an area of the opposing surface regions and conducting reverse ion-exchange while presenting the reverse ion-exchange medium to lessen the compressive stress in said surface region relative to the treatment-disadvantaged surface region opposing and thereby produce a chemically-strengthened substrate having less curvature than is present in the chemically-strengthened glass substrate prior to reverse ion-exchange, or
• (2) presenting the reverse ion-exchange medium to only one of a treatment-advantaged surface region or a treatment-disadvantaged surface region within at least an area of the opposing surface regions and conducting reverse ion-exchange while presenting the reverse ion-exchange medium to lessen the compressive stress in said surface region relative to the surface region opposing and thereby produce a chemically-strengthened substrate having a predetermined profile of curvature which is not present in the chemically-strengthened glass substrate prior to reverse ion-exchange.