METHOD OF MAKING VACUUM INSULATED PANEL

1 . A method of making a vacuum insulating panel, the vacuum insulating panel comprising a first glass substrate, a second glass substrate, a plurality of spacers provided in a gap between at least the first and second glass substrates, and a seal provided at least partially between at least the first and second glass substrates, the seal comprising a first seal layer and a second seal layer; wherein the method comprises:

firing and/or sintering second seal material to form the second seal layer;

providing first seal material for the first seal layer in a location contacting the second seal layer;

heating the first seal material in order to form the first seal layer;

wherein, after said heating, the first seal layer comprises from about 20-70 wt. % tellurium oxide and the second seal layer comprises bismuth oxide and/or boron oxide;

wherein said heating causes formation of the first seal layer so that induced transient thermal stress in the first seal layer does not exceed about 25 MPa, and the first seal layer has a density from about 2.8-4.0 g/cm 3 ; and

after forming the first seal layer, evacuating the gap to a pressure less than atmospheric pressure.

2 . The method of claim 1 , wherein the heating comprises laser heating.

3 . The method of claim 2 , wherein the lateral speed of a laser beam used in said laser heating is from about 5-70 mm/second.

4 . The method of claim 1 , wherein said heating is performed so that induced transient thermal stress in the first seal layer does not exceed about 18 MPa.

5 . The method of claim 1 , wherein the heating comprises laser heating using a laser beam that moves laterally for at least some period of time at a lateral speed of from about 5-70 mm/second, and wherein the first seal material comprises tellurium oxide, the tellurium oxide comprising TeO 4 and TeO 3 , and wherein the first seal material comprises more TeO 4 than TeO 3 by wt. % so that TeO 4 >TeO 3 in terms of wt. % in the first seal material; and wherein said laser heating causes the TeO 4 >TeO 3 in the first seal material to transform into TeO 3 >TeO 4 due to said laser heating, whereby an amount of TeO 4 decreases and an amount of TeO 3 increases due to said laser heating, so that after said laser heating and formation of the first seal layer, the first seal layer comprises more TeO 3 than TeO 4 by wt. %, and comprises from about 20-80% wt. % tellurium oxide.

6 . The method of claim 1 , wherein the first seal layer comprises from about 40-70 wt. % tellurium oxide and from about 12-40 wt. % vanadium oxide.

7 . The method of claim 1 , wherein the seal comprises a third seal layer comprising boron oxide and/or bismuth oxide, and wherein the first seal layer is at least partially located between at least the second and third seal layers.

8 . The method of claim 1 , wherein said firing and/or sintering the second seal material is performed while thermally tempering at least one of the glass substrates, to form the second seal layer.