METHOD OF MAKING VACUUM INSULATED PANEL WITH PRE-HEATING AND LASER HEATING

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:

providing first seal material for the first seal layer at a location at least partially between at least the first and second glass substrates;

pre-heating the glass substrates, the first seal material, and the second seal layer;

wherein said pre-heating causes at least one of (a) at least one of the glass substrates, (b) the second seal layer, and/or (c) the first seal material, to reach a pre-heat temperature;

wherein the pre-heat temperature is from about 40-120 degrees C. less than a melting point (Tm) of the first seal material, from about 150-450 degrees less than a melting point (Tm) of the second seal material, and within about 70 degrees C. of a softening point (Ts) of the first seal material;

after said pre-heating, laser heating the first seal material in order to fire and/or sinter the first seal material and form the first seal layer in a manner so that the first seal layer has a density of 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 pre-heat temperature is from about 50-100 degrees C. less than the melting point (Tm) of the first seal material, from about 200-400 degrees less than the melting point (Tm) of the second seal material, and within about 50 degrees C. of the softening point (Ts) of the first seal material.

3 . The method of claim 1 , wherein the pre-heat temperature is from about 60-90 degrees C. less than the melting point (Tm) of the first seal material, and within about 30 degrees C. of the softening point (Ts) of the first seal material.

4 . The method of claim 1 , wherein the pre-heat temperature is at least 5 degrees C. greater than a transition temperature (Tg) of the first seal material.

5 . The method of claim 1 , wherein the pre-heat temperature is at least 10 degrees C. greater than a transition temperature (Tg) of the first seal material.

6 . The method of claim 1 , wherein the pre-heat temperature is from about 280-340 degrees C.

7 . The method of claim 1 , wherein the pre-heat temperature is from about 300-340 degrees C.

8 . The method of claim 1 , wherein the pre-heat temperature is from about 310-330 degrees C.

9 . The method of claim 1 , wherein said laser heating is performed using a laser, and said pre-heating is performed in an oven.

10 . The method of claim 9 , wherein the laser is a near-IR laser.

11 . The method of claim 1 , wherein said pre-heating and laser heating are each performed in a manner so that induced transient thermal stress in the glass substrates does not exceed about 20 MPa.

12 . The method of claim 1 , wherein a thermal conductivity of the second seal layer is greater than a thermal conductivity of the first substrate and greater than a thermal conductivity of the first seal layer.

13 . The method of claim 12 , wherein the second seal layer has a thermal conductivity of from 1.0 to 1.50 W/mK, and the first seal layer has a thermal conductivity of from 0.80 to 1.00 W/mK.

14 . The method of claim 1 , wherein a width of the first seal layer is from about 3-9 mm.

15 . The method of claim 1 , wherein a laser during said laser heating emits a wavelength of from about 780-1064 nm.

16 . The method of claim 1 , wherein the method further comprises, prior to said pre-heating, firing and/or sintering second seal material for the second seal layer while thermally tempering or heat strengthening at least one of the glass substrates, to form the second seal layer.

17 . The method of claim 1 , wherein the seal further comprises a third seal layer, and wherein the first seal layer is located between the second and third seal layers in the panel.

18 . The method of claim 14 , wherein said laser heating comprises causing a laser beam to move at a lateral speed of from about 5-70 mm/second relative to the substrates and the first seal material so that the laser beam at least partially passes through at least one of the glass substrates and impinges upon at least the second seal layer in order to heat the second seal layer and fire and/or sinter the first seal material thereby forming the first seal layer.

19 . The method of claim 18 , wherein the lateral speed of the laser beam is from about 10-30 mm/second.

20 . The method of claim 1 , wherein the first seal layer has a physical thickness of from about from about 30-120 μm.

21 . The method of claim 1 , wherein the second seal layer is configured to be located between at least the first seal material and a laser used for said laser heating, wherein the second seal layer has a physical thickness of from about from about 20-70 μm, and wherein the first seal layer is thicker than the second seal layer.

22 . The method of claim 1 , wherein the first seal material comprises tellurium oxide and vanadium oxide, the first seal material comprising more tellurium oxide than vanadium oxide by wt. %, and wherein prior to said laser heating the first seal material comprises from about 20-70 wt. % 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 the first seal layer comprises more TeO 3 than TeO 4 by wt. %, and comprises from about 20-80% wt. % tellurium oxide.

23 . The method of claim 22 , wherein said laser heating causes a ratio TeO 4 :TeO 3 to change from about 1.0 to 2.0 in the first seal material prior to said laser heating, to from about 0.05 to 0.40 in the first seal layer after said laser heating.

24 . The method of claim 22 , wherein said laser heating causes a ratio TeO 4 :TeO 3 to change from about 1.2 to 1.6 in the first seal material prior to said laser heating, to from about 0.10 to 0.30 in the first seal layer after said laser heating.

25 . The method of claim 22 , wherein from about 60-95% of Te in the first seal layer is in a form of TeO 3 after said laser heating.

26 . The method of claim 22 , wherein the vanadium oxide comprises VO 2 and V 2 O 5 , and wherein prior to said laser heating said first seal material comprises more V 2 O 5 than VO 2 by wt. %, and wherein said laser heating causes a relationship V 2 O 5 >VO 2 in the first seal material to transform into VO 2 >V 2 O 5 due to said laser heating, whereby an amount of VO 2 increases and an amount of V 2 O 5 decreases due to said laser heating, so that after said laser heating the first seal layer comprises more VO 2 than V 2 O 5 by wt. %.

27 . The method of claim 26 , wherein said laser heating causes a ratio V 2 O 5 :VO 2 to change from about 3.0 to 8.0 in the first seal material prior to said laser heating, to from about 0.20 to 0.80 in the first seal layer after said laser heating.

28 . The method of claim 26 , wherein from about 50-75% of V in the first seal layer is in a form of VO 2 after said laser heating.

29 . 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.

30 . The method of claim 1 , wherein the second seal layer comprises bismuth oxide and boron oxide, and where the second seal layer comprises from about 1-40 mol % bismuth and from about 3-40 mol % boron on an elemental basis, and wherein the second seal layer comprises at least two times more boron than bismuth on an elemental basis in terms of mol %.

31 . The method of claim 1 , wherein the seal is a hermetic edge seal of the vacuum insulating panel.

32 . The method of claim 1 , wherein the first seal layer has a density of at least about 3.0 g/cm 3 .

33 . The method of claim 1 , wherein said laser heating causes the first seal material to be heated to a temperature above the melting point (Tm) of the first seal material.

34 . 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; wherein the method comprises:

providing first seal material for the first seal layer at a location at least partially between at least the first and second glass substrates;

pre-heating the glass substrates and the first seal material;

wherein said pre-heating causes at least one of (a) at least one of the glass substrates, and/or (b) the first seal material, to reach a pre-heat temperature;

wherein the pre-heat temperature is from about 40-120 degrees C. less than a melting point (Tm) of the first seal material, from about 150-450 degrees less than a melting point (Tm) of the second seal material, and within about 70 degrees C. of a softening point (Ts) of the first seal material,

after said pre-heating, laser heating the first seal material in order to fire and/or sinter the first seal material and form the first seal layer in a manner so that the first seal layer has a density of from about 2.8-4.0 g/cm 3 ;

wherein said laser heating causes the first seal material to be heated to a temperature above the melting point (Tm) of the first seal material; and

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

35 . 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; wherein the method comprises:

providing first seal material for the first seal layer at a location at least partially between at least the first and second glass substrates;

pre-heating the glass substrates and the first seal material;

wherein said pre-heating causes at least one of (a) at least one of the glass substrates, and/or (b) the first seal material, to reach a pre-heat temperature;

wherein the pre-heat temperature is from about 40-120 degrees C. less than a melting point (Tm) of the first seal material, from about 150-450 degrees less than a melting point (Tm) of the second seal material, and within about 70 degrees C. of a softening point (Ts) of the first seal material,

after said pre-heating, laser heating the first seal material in order to fire and/or sinter the first seal material and form the first seal layer;

wherein the first seal material, after said laser heating, comprises from about 20-80% tellurium oxide, the tellurium oxide comprising TeO 4 and TeO 3 , and wherein the first seal layer comprises more TeO 3 than TeO 4 by wt. %, and wherein a ratio TeO 4 :TeO 3 in the first seal layer is from about 0.05 to 0.40; and

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