Method and apparatus for making vacuum insulated glass (VIG) window unit including pump-out tube
A vacuum insulated glass (VIG) window assembly and method for making same is provided in which dimensions of a hole formed in a glass substrate in which a pump-out tube is to be inserted is selected such that it provides sufficient clearance for efficient insertion and accommodates sufficient adhesive material (e.g., frit inclusive paste), while at the same time providing sufficient support to resist substantial tilting or tipping of the pump-out tube when inserted in the hole. In addition, a length of the pump-out tube is selected so that a distance between a top of the pump-out tube (which is later subjected to heat sealing, e.g., by a laser or the like) and an interface between the pump-out tube and the fit material proximate the hole exiting the glass substrate is in a range that reduces the likelihood of heat conduction sufficient to cause cracking of the pump-out tube at the pump-out tube/frit interface caused, for example, by thermal shock due to a temperature differential between the glass of the pump-out tube and the frit material.
1. A vacuum insulated glass window unit comprising:
a first glass substrate and a second glass substrate, the first and second glass substrates spaced apart from each other;
a plurality of spacers and a seal provided between the first and second glass substrates;
wherein the first glass substrate has a hole defined therein for receiving a pump-out tube and a frit inclusive paste; and
wherein the pump-out tube and the frit inclusive paste are disposed in said hole, a portion of the frit inclusive paste forms a bump of frit inclusive paste proximate a top of the hole where the hole exits the first glass substrate and substantially surrounding a portion of the pump-out tube and having a height measured from a surface of the first glass substrate, wherein a difference between the height of the bump of frit inclusive paste and a height of the pump-out tube extending out of the hole is in a range of from 4.5 to 6.0 mm.
2. The vacuum insulated glass window unit of claim 1 , wherein a difference between the height of the bump of frit inclusive paste and the height of the pump-out tube extending out of the hole is in a range of from about 4.8 to 5.5 mm.
3. The vacuum insulated glass window unit of claim 1 , wherein a difference between the height of the bump of frit inclusive paste and the height of the pump-out tube extending out of the hole is about 5.0 mm.
4. The vacuum insulated glass window unit of claim 1 , wherein the seal comprises an edge seal, wherein the first substrate and the second substrate are arranged to sandwich the plurality of spacers and edge seal therebetween to form a cavity between the first and second substrates, wherein the cavity is at a pressure less than atmospheric pressure.