Reinforced window member and method of manufacturing the same

A method of manufacturing a window member, comprising:

• performing a first reinforcement operation including performing a first ion-exchange treatment on an initial window member, the first ion-exchange treatment comprising exchanging some first ions in the initial window member to second ions different from the first ions, thereby giving the initial window member a first surface compressive stress and a first depth of compression, wherein remaining first ions in the initial window member that are present after the first ion-exchange treatment are not exchanged as part of the first reinforcement operation;
• performing a stress relief operation including performing a salt treatment on the initial window member to which the first reinforcement operation is performed, thereby moving the second ions of the initial window member to be closer to a center depth of the initial window member than at least some of the remaining first ions of the initial window member are and thereby decreasing the first surface compressive stress to a second surface compressive stress and thereby changing the first depth of compression to a second depth of compression located at a region closer to the center depth of the initial window member than the first depth of compression, the second depth of compression being different from the first depth of compression;
• and
• performing a second reinforcement operation including performing a second ion-exchange treatment on the initial window member to which the stress relief operation is performed, thereby increasing the second surface compressive stress to a third surface compressive stress,
• wherein the second reinforcement operation provides a single salt to the initial window member to which the stress relief operation is perforated, and
• wherein the initial window member to which the second reinforcement operation is performed has a third depth of compression greater than the first depth of compression, and the second reinforcement operation controls a first variation in compressive stress according to a depth in a section between a surface of the initial window member to which the second reinforcement operation is performed and a first depth value smaller than the third depth of compression to be greater than a second variation in compressive stress according to a depth in a section between a surface of the initial window member to which the first reinforcement operation is performed and the first depth value.

A method of manufacturing a window member, comprising:

• performing a first reinforcement operation comprising an ion-exchange treatment operation that exposes an initial window member to a first reinforcement environment at a first temperature equal to or greater than about 500° C., the first reinforcement environment comprising a first ion, the performing of the first reinforcement operation resulting in the first ion being present within the initial window member;
• performing a second reinforcement operation comprising providing the first-reinforced initial window member to a second reinforcement environment at a second temperature smaller than about 500° C. thereby performing an ion-exchange treatment on the first-reinforced initial window member, the second reinforcement environment comprising a second ion, the performing of the second reinforcement operation resulting in the second ion being present within the initial window member at a concentration that is depth-dependent;
• and
• performing a stress relief operation that includes performing a heat treatment and/or a salt treatment on the initial window member to which the first reinforcement operation is performed, wherein the second reinforcement operation is performed after the stress relief operation is performed,
• wherein the first reinforcement environment further comprises a mixed salt comprising a first salt comprising the first ion and a second salt different from the first salt, the initial window member comprises a third ion different from the first ion, and the first reinforcement operation substitutes the first ion for the third ion, and
• wherein the first reinforcement operation further comprises an alkalinity control operation alleviating an alkalinity of the first reinforcement environment, the alkalinity control operation including providing a silicon nitride-based material as an additive in the first reinforcement operation,
• wherein an ion concentration of the second ion at a region having a depth within a range from a surface of the initial window member to a particular depth of the initial window member is greater after the performance of the first reinforcement operation than after the stress relief operation is performed, and
• wherein the ion concentration of the second ion at a region having a depth from the particular depth to the center depth of the initial window member is smaller after the first reinforcement operation is performed than after the stress relief operation is performed.