FLANGED TUBE FOR VACUUM INSULATED GLASS (VIG) UNIT EVACUATION AND HERMETIC SEALING, VIG UNIT INCLUDING

FLANGED TUBE, AND ASSOCIATED METHODS

TECHNICAL FIELD

[0001] Certain example embodiments of this invention relate to vacuum insulated glass (VIG) units, and/or methods of making the same. More particularly, certain example embodiments of this invention relate to a flanged pump-out tube for VIG unit evacuation and hermetic sealing, a VIG unit subassembly including a flanged pump-out tube, a VIG unit made using a flanged pump-out tube, and/or associated methods.

BACKGROUND AND SUMMARY

[0002] Vacuum insulating glass (VIG) units typically include at least two spaced apart glass substrates that enclose an evacuated or low-pressure space/cavity therebetween. The substrates are interconnected by a peripheral edge seal and typically include spacers between the glass substrates to maintain spacing between the glass substrates and to avoid collapse of the glass substrates that may be caused due to the low pressure environment that exists between the substrates. Some example VIG configurations are disclosed, for example, in U.S. Patent Nos. 5,657,607, 5,664,395, 5,902,652, 6,506,472 and 6,383,580 the disclosures of which are all hereby incorporated by reference herein in their entireties.

[0003] Figs. 1-2 illustrate a typical VIG unit 1 and elements that form the VIG unit 1. For example, VIG unit 1 may include two spaced apart substantially parallel glass substrates 2, 3, which enclose an evacuated low- pressure space/cavity 6 therebetween. Glass sheets or substrates 2,3 are interconnected by a peripheral edge seal 4 which may be made of fused solder glass, for example. An array of support pillars/spacers 5 may be included between the glass substrates 2, 3 to maintain the spacing of substrates 2, 3 of the VIG unit 1 in view of the low-pressure space/gap 6 present between the substrates 2, 3.

[0004] A pump-out tube 8 may be hermetically sealed by, for example, solder glass 9 to an aperture/hole 10 that passes from an interior surface of one of the glass substrates 2 to the bottom of an optional recess 11 in the exterior surface of the glass substrate 2, or optionally to the exterior surface of the glass substrate 2. A vacuum is attached to pump-out tube 8 to evacuate the interior cavity 6 to a low pressure, for example, using a sequential pump down operation. After evacuation of the cavity 6, a portion (e.g., the tip) of the tube 8 is melted to seal the vacuum in low pressure cavity/space 6. The optional recess 11 may retain the sealed pump-out tube 8. Optionally, a chemical getter 12 may be included within a recess 13 that is disposed in an interior face of one of the glass substrates, e.g., glass substrate 2. The chemical getter 12 may be used to absorb or bind with certain residual impurities that may remain after the cavity 6 is evacuated and sealed.

[0005] VIG units with fused solder glass peripheral edge seals 4 are typically manufactured by depositing glass frit, in a solution (e.g., frit paste), around the periphery of substrate 2 (or on substrate 3). This glass frit paste ultimately forms the glass solder edge seal 4. The other substrate (e.g., 3) is brought down on substrate 2 so as to sandwich spacers/pillars 5 and the glass frit solution between the two substrates 2, 3. The entire assembly including the glass substrates 2, 3, the spacers/pillars 5 and the seal material (e.g., glass frit in solution or paste), is then heated to a temperature of at least about 500 degrees

C, at which point the glass frit melts, wets the surfaces of the glass substrates 2,

3, and ultimately forms a hermetic peripheral/edge seal 4.

[0006] After formation of the edge seal 4 between the substrates, a vacuum is drawn via the pump-out tube 8 to form low pressure space/cavity 6 between the substrates 2, 3. The pressure in space 6 may be produced by way of an evacuation process to a level below atmospheric pressure, e.g., below about 10 ² Torr. To maintain the low pressure in the space/cavity 6, substrates 2, 3 are hermetically sealed. Small, high strength spacers/pillars 5 are provided between the substrates to maintain separation of the approximately parallel substrates against atmospheric pressure. As noted above, once the space 6 between substrates 2, 3 is evacuated, the pump-out tube 8 may be sealed, for example, by melting its tip using a laser or the like.

[0007] A typical process for installing the pump-out tube 8 in the hole or aperture 10 includes inserting a pre-formed glass pump-out tube 8 in an aperture/hole 10 that has previously been formed (e.g., by drilling) in one of the glass substrates 2. After the pump-out tube 8 has been seated in the

aperture/hole 10, an adhesive frit paste is applied to the pump-out tube 8, typically in a region close to the opening of the hole 10 proximate an exterior surface of the glass substrate 2. As noted above, the pump-out tube may be sealed after evacuation or purging of the VIG unit cavity.

[0008] After evacuation of the cavity to a pressure less than atmospheric, sealing of the pump-out tube may be accomplished by heating an end of the pump-out tube that is used to evacuate or purge the cavity to melt the opening and thus seal the cavity of the VIG unit. For example and without limitation, this heating and melting may be accomplished by laser irradiation of the tip of the pump-out tube.

[0009] It sometimes may be the case that the pump-out tube may not be properly seated in the hole formed in the glass substrate. As a result, the pump out tube may lean or tilt to one side, and thus not be substantially perpendicular to the surface of the glass substrate in which the hole is formed. As a result, in situations where the pump-out tube is improperly seated and is at an

undesirable angle with respect to the surface of the glass substrate, it can become difficult to properly seal the pump-out tube because the laser cannot consistently melt the tip of the pump-out tube because of, for example, differences in distance between various portions of the angled pump-out tube top and the laser source. Inconsistent melting of the top of the pump-out tube may result in incomplete sealing and thus air leakage, which may, depending on the quality of the seal, occur rapidly or more slowly over time. In addition, based on the degree of tilt or tipping of the tube, the laser could hit the tube wall instead of the top. If the laser hits the tube wall, the laser could potentially bypass the tube and hit the frit, which may damage the frit or cause undesirable outgassing into the cavity.

[0010] It would seem desirable to provide a way to seat the pump-out tube in the hole to reduce the amount of tipping of the tube to be within an acceptable range. In this regard, attempts have been made to improve the evacuation and/or tip-off processes. See, for example, U.S. Patent Nos.

9,371,683 and 8,833,105, as well as U.S. Publication No. 2013/0306222, the entire contents of each of which are hereby incorporated herein by reference. Such techniques are advantageous compared to conventional approaches. Yet the inventors of the instant application have recognized that further

improvements are still possible.

[0011] For example, even when pump-out tubes are properly oriented with respect to the substrate, they still protrude outwardly from an outmost surface of the VIG unit. If the sealed tube is jostled, knocked loose, or broken in whole or in part, the VIG unit may lose vacuum faster than otherwise would be desirable. Caps sometimes are provided over protruding sealed tubes to help protect against shocks that might cause breakage and the like, but such caps have a limited effectiveness against heavy mechanical forces and add additional processing steps and materials to the VIG unit manufacturing process.

[0012] This conventional arrangement is shown more fully in Fig. 3, which is a cross-sectional schematic view of a VIG unit having a sealed pump out tube 8 that protrudes outwardly from the VIG unit and is protected using a cap 15. When evacuating and subsequently sealing the VIG unit, the pump-out port is used to allow an evacuation path. Conventionally, this port is sealed by inserting a tube 8 with frit 9 applied thereon into a hole drilled in the glass 2, firing the frit 9 around the hole, sealing the frit 9 in place, and sealing the tube

8 by melting it with a laser, resistive filament, or similar focused energy source, thereby hermetically sealing the VIG unit. A protective cap 15 is attached to the glass surface via adhesive tape 16 or other means to help protect the delicate tube 8 that protrudes from the glass surface.

[0013] Thus, it will be appreciated that it would be desirable to completely eliminate the need for a pump-out tube that protrudes outwardly from an outmost surface of the VIG unit and/or the cap therefor.

[0014] One aspect of certain example embodiments relates to the use of a pump-out tube internal to the VIG unit. In certain example embodiments, there is no need for a pump-out tube that protrudes outwardly from an outmost surface of the VIG unit. This arrangement in certain example instances simplifies the manufacturing process, e.g., by removing the need to provide and seal a separate cap, making shipping, handling, transportation, and/or other processing operations easier because less care has to be taken by virtue of the elimination of a critical through very fragile element of the VIG unit. Frame design, lamination, IG construction, and/or the like also can be simplified.

[0015] Another aspect of certain example embodiments relates to the sealing of the flanged pump-out tube such that the sealed tube does not protrude past an outermost surface of (e.g., is flush with or lies within) the VIG unit. This arrangement is advantageous in certain example instances because it can reduce and sometimes eliminate the need for a separate protruding protective cap placed above the tube. The removal of the protective cap, in turn, can be advantageous from an aesthetic perspective. Moreover, the removal of the protective cap can be advantageous in terms of reducing the likelihood of damage to the VIG unit and making shipping, handling, transportation, and/or other processing operations easier. With respect to the former, as alluded to above, bumping the cap can translate force to the sealed tube, which can cause it to move and/or break, compromising the quality of the vacuum of the VIG. With respect to the latter, because the cap is missing, it may be possible to avoid having to use special shipping and/or packaging materials that accommodate such caps.

[0016] Another aspect of certain example embodiments involves a redesigned VIG pump-out port and/or tube. The redesigned VIG pump-out port and/or tube advantageously improve vulnerabilities related to shearing loads and/or the like, e.g., by virtue of the elimination of a tube extending beyond an outermost plane of the VIG unit.

[0017] In certain example embodiments, a method of making a VIG unit is provided. There are provided first and second glass substrates. The first substrate includes a hole formed therein, with the hole being formed to have first and second portions, with the first portion being closer to an outer surface of the first substrate than the second portion, with the first portion having a first width across the first substrate and the second portion having a second width across the first substrate, and with the first width being wider than the second width, the first and second portions together forming a through-hole through the first substrate. A flanged pump-out tube including a skirt intermediate upper and lower portions is placed in the hole, such that the lower portion of the tube extends into the second portion and the upper portion of the tube is located in the first portion. The first and second substrates are sealed together in connection with an edge seal provided around peripheral edges of the first and/or second substrates, with a cavity being defined by the first and second substrates, and with a plurality of spacers being provided between the first and second substrates in the cavity and helping to maintain the first and second substrates in substantially parallel, spaced-apart relation to one another. The cavity is evacuated to a pressure less than atmospheric. The pump-out tube is heated so as to cause at least a part of the upper portion of the tube to collapse inwardly upon itself, covering the second width and hermetically sealing the VIG unit and forming a sealed tube, the sealed tube being flush with, or partially recessed with respect to, an outermost surface of the first substrate. [0018] In certain example embodiments, a method of making a VIG unit subassembly is provided. The method includes providing a first glass substrate including a hole formed therein, with the hole being formed to have first and second portions, with the first portion being closer to an outer surface of the first substrate than the second portion, with the first portion having a first width across the first substrate and the second portion having a second width across the first substrate, and with the first width being wider than the second width, the first and second portions together forming a through-hole through the first substrate. The first substrate is forwarded to another party to: place in the hole a flanged pump-out tube including a skirt intermediate upper and lower portions such that the lower portion of the tube extends into the second portion and the upper portion of the tube is located in the first portion; seal together the first glass substrate with a second substrates in connection with an edge seal provided around peripheral edges of the first and/or second substrates, a cavity being defined by the first and second substrates, and a plurality of spacers being provided between the first and second substrates in the cavity and helping to maintain the first and second substrates in substantially parallel, spaced-apart relation to one another; evacuate the cavity to a pressure less than atmospheric; and laser heat the pump-out tube so as to cause at least a part of the upper portion of the tube to collapse inwardly upon itself, covering the second width and hermetically sealing the VIG unit and forming a sealed tube, the sealed tube being flush with, or partially recessed with respect to, an outermost surface of the first substrate.

[0019] In certain example embodiments, a VIG unit is provided. First and second glass substrates are maintained in substantially parallel, spaced apart relation to one another via a hermetic edge seal and a plurality of spacers disposed in a cavity defined between the first and second glass substrates. The cavity is evacuated to a pressure less than atmospheric using a pump-out port formed in the first substrate that has been hermetically sealed with a laser- sealed flanged tube. The laser-sealed tube includes a sealing portion made therefrom proximate to the cavity, with the laser-sealed tube being located internal to the VIG unit without protruding thereform.

[0020] The features, aspects, advantages, and example embodiments described herein may be combined to realize yet further embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] These and other features and advantages may be better and more completely understood by reference to the following detailed description of exemplary illustrative embodiments in conjunction with the drawings, of which:

[0022] FIGURE l is a cross-sectional schematic diagram of a conventional vacuum insulated glass (VIG) unit;

[0023] FIGURE 2 is a top plan view of a conventional VIG unit;

[0024] FIGURE 3 is a cross-sectional schematic view of a VIG unit having a sealed pump-out tube that protrudes outwardly from the VIG unit and is protected using a cap;

[0025] FIGURE 4 is a cross-sectional schematic view of a flanged tube that may be used in certain example embodiments;

[0026] FIGURE 5 is a cross-sectional schematic view showing an example substrate design that may be used in certain example embodiments;

[0027] FIGURE 6 is a cross-sectional schematic view demonstrating a first way in which a flanged pump-out tube can be provided to a VIG unit subassembly to be sealed, in accordance with certain example embodiments;

[0028] FIGURE 7 is a cross-sectional schematic view showing the Fig. 6 example VIG unit subassembly sealed in accordance with certain example embodiments;

[0029] FIGURE 8 is a cross-sectional schematic view demonstrating a second way in which a flanged pump-out tube can be provided to a VIG unit subassembly to be sealed, in accordance with certain example embodiments; [0030] FIGURE 9 is a cross-sectional schematic view showing the Fig. 8 example VIG unit subassembly sealed in accordance with certain example embodiments;

[0031] FIGURE 10 is a cross-sectional schematic view showing an example VIG unit subassembly lacking a top pocket that has been sealed in accordance with certain example embodiments;

[0032] FIGURE 11 is a cross-sectional schematic view showing an example VIG unit subassembly with top and bottom pockets that has been sealed in accordance with certain example embodiments;

[0033] FIGURE 12 is a flowchart showing an example process for making a VIG unit in connection with a flanged pump-out tube, in accordance with certain example embodiments; and

[0034] FIGURE 13 is a flowchart showing another example process for making a VIG unit in connection with an internal seal, in accordance with certain example embodiments.

DETAILED DESCRIPTION

[0035] Certain example embodiments relate to improved techniques for evacuating vacuum insulated glass (VIG) units. More particularly, certain example embodiments of this invention relate to a flanged pump-out tube for VIG unit evacuation and hermetic sealing, a VIG unit subassembly including a flanged pump-out tube, a VIG unit made using a flanged pump-out tube, and/or associated methods. Typically, the internal space of a VIG unit is evacuated through a surface mounted tube or other structure that facilitates sealing once the internal space reaches sufficiently low pressures. That tube or other structure protrudes from the surface even when sealed and typically is protected with a protective cap but nonetheless oftentimes requires special handling. Certain example embodiments improve upon this approach by using a flanged sealing tube that is tipped off so that an upper part thereof does not protrude beyond an outermost surface of the VIG unit, thereby potentially eliminating the need for a protective cap and allowing for more freedom in handling, frame design, hybrid VIG construction, lamination, and the like. In essence, the flanged sealing tube is relocated to an internal surface within a recessed pocket, at least in certain example embodiments.

[0036] In certain example embodiments, the sealed tube is flush with, or recessed with respect to, the outer surface of the glass of the VIG. As a result, a protective cap need not be applied thereover. This in turn can lead to easier processing, especially for secondary processes such as lamination, hybrid VIG manufacturing, etc. Additionally, the elimination of an external tube that protrudes outwardly from the substrate may allow for improvements to be realized in shipping approaches, e.g., as additional packing dunnage to properly space apart the VIG units to account for the extra protrusion need not be provided. Standard, or more standard, packaging and the like may be used in certain example embodiments.

[0037] There are multiple flanged tube and substrate pocket designs that may be used in connection with different example embodiments. In this regard, and referring now more particularly to the drawings in which like numerals indicate like components throughout the several views, Fig. 4 is a cross-sectional schematic view of a flanged tube that may be used in certain example embodiments, and Fig. 5 is a cross-sectional schematic view showing an example substrate design that may be used in certain example embodiments.

[0038] The Fig. 4 example flange includes a cylindrical or other hollow shaped tube 40, with a protruding feature 42 somewhere along its total length L4. In the Fig. 4 example, the tube 40 has an inner diameter or inner distance D1 and an outer diameter or outer distance D2, with the walls of the tube being defined therebetween. Also in the Fig. 4 example, the protruding feature 42is intermediate upper and lower ends of the tube 40, e.g., so that it spaced a first distance LI from an upper end of the tube 40 and spaced a second distance L3 from a lower end of the tube 40, with a length or thickness of L2. The protruding feature 42 has a diameter or major distance D3.

[0039] This protruding feature 42 acts as a flange, providing several potential processing improvements along with product improvements, as will be appreciated more fully from the description provided below. The tube 40 is formed as one piece in certain example embodiments. For instance, in certain example embodiments, the body of the tube 40 and the protruding feature 42 both are formed form the same material (e.g., glass). In certain example embodiments, the tube 40 and the protruding feature 42 may be considered integral with one another even though they are formed from different materials.

[0040] The tube 40 is inserted into a hole or pocket feature formed in a glass substrate that is, or will become, part of a VIG unit subassembly. The tube 40 is hermetically sealed to the glass substrate in this hole or pocket using a frit. Fig. 5 shows a substrate 50 with a pump-out port 52. Recesses 54a-54b are formed proximate to the pump-out port 52. The pump-out port 52 and recesses 54a-54b may be cylindrical or otherwise shaped. As shown in Fig. 5, the pump-out port 52 has a through diameter or major distance THD, and the recesses 54a-54b have diameters or distances of DPI and DP2 respectively.

The substrate has a thickness ST, and the recesses 54a-54b have depths of PI and P2 respectively. As explained in greater detail below, different

embodiments may include the upper recess 54a, the lower recess 54b, or both recesses 54a-54b.

[0041] Sealing frit can be applied along the outermost diameter of the tube (e.g., as shown in Fig. 6) and/or applied between a top or bottom surface of the flange diameter between D2 and D3 and the surface of the pocket (e.g., see Fig. 8, showing frit on the top surface). The flange feature allows for the sealing frit to be covered with respect to the laser used in sealing the tube (as in the Fig. 8 example, for instance), and/or moved out of the way of the laser path

(as in the Fig. 6 example, for instance). Locating the frit away from, and/or in place shielded with respect to, the laser can be advantageous, as laser exposure of the frit can promote defects in the seal, problems with the tube sealing, the buildup of fog, and/or other issues with the processing of the VIG units.

[0042] The flange feature acts as a vertical stop and helps maintain the perpendicular or substantially perpendicular relation between the tube end and the surface of the glass.

[0043] When the flange is provided on the interior VIG unit surface, a thermal break may be provided. This thermal break advantageously allows for proper sealing of the tube. As a result, a clearance may be provided between the substrate through-hole diameter or distance THD and the outer tube diameter or distance D2. See, for example, Figs. 10-11 in this regard. This clearance can be near zero, up to within about 1 mm of the outer diameter or distance D3 of the tube assembly. The bottom pocket promotes centering of the tube. Although not necessarily required for sealing in this arrangement, a top pocket nonetheless may be desirable for inspection or other purposes.

[0044] The flange feature, if used as a datum from the exterior pocket surface, allows a VBZ-based (vanadium, barium, and zinc based) or other frit to be used in both the edge-sealing and tube connection processes. This advantageously allows one common material to be used in multiple locations. Example VBZ-based and/or other frits that may be used in connection with certain example embodiments are disclosed in U.S. Patent Nos. 10,125,045; 9,988,302; 9,593,527; 9,428,952; and 9,309,146, the entire contents of each of which are hereby incorporated herein by reference.

[0045] The flange feature, if used as a datum on the interior pocket surface (e.g., surface 2 or surface 3 of the resulting VIG unit), allows for firing of the tube during tempering, utilizing a bismuth or other frit seal, reducing the vulnerability to condensed water to which some VBZ-based and/or other frits are susceptible.

[0046] Lengths LI and L3 are not required to be symmetrical and can be zero values (e.g., as shown in Fig. 8, where L3 = 0.00 mm). If LI and L3 are symmetrical, however, installation operations may be facilitated through easier and more reliable orientation of the tube vis-a-vis the pump-out port.

[0047] In certain example embodiments, the thickness L2 of the skirt or protruding feature can range from 0.30 mm up to one half of the substrate thickness ST, less the thickness remaining from the sealing operation (which is typically up to 0.75 mm). In certain example embodiments where it is desirable to heat treat (e.g., thermally temper) the substrate that is to accommodate the flanged pump-out tube, the total glass possible to remove in the pocket depths PI and P2 is up to one half the total thickness of the substrate. Removal of more glass may be incompatible with high-temperature tempering or the like in some instances. Thus, in certain example

embodiments:

L2 = (0.30 mm to [(ST/2) - 0.75 mm]}

PI + P2 < (ST/2)

PI does not necessarily equal P2

[0048] With the top or exterior pocket flange datum, the sum of the thickness of the skirt L2 and the final tube length, if sealing from the exterior, preferably is not be greater than one half the substrate thickness. This helps ensure that the tube does not extend outwardly from an outermost surface of the VIG unit. Thus, in certain example embodiments:

[0049] L2 + 0.75 < (ST/2), L2 + 0.75 = PI

[0050] With the bottom or interior pocket flange datum, the total tube length L4 preferably is no greater than the substrate thickness plus 0.75 mm, and the depth of the pocket PI preferably is equal to 0.75 mm at a minimum.

The flange thickness falling within the range given above, maintaining the one- half substrate thickness or less, allows for up to 0.200 mm sealing frit material if bonded on diameter to pocket (see Fig. 8). Thus, in certain example embodiments:

(ST - 0.200 mm) < L4 < ST + 0.75 mm

PI > 0.75 mm

P2 + P1 < ST/2

P2 = (ST/2) - PI - 0.200

P2 = L2 + 0.200

[0051] The flange diameter or distance preferably is at least 1 mm greater than the exterior tube end diameter or distance, and at least 2 mm smaller than the pocket diameter or distance in which the flange is placed. This advantageously allows space for excess material and/or for the edge of flange to be sealed to the substrate.

[0052] In certain example embodiments, the tube end outer diameter or distance preferably is no greater than 2 mm larger than the inner tube end diameter. This arrangement advantageously enables the tube to be tipped off efficiently using a laser. Thus, in certain example embodiments:

D3 - D2 > 1.00 mm

D3 < (DPI or DP2 - 2.00 mm), DPI or DP2 depending on pocket of insertion. D2 - D1 < 2.00 mm

D1 > 0.50 mm

[0053] Where a thermal conduction break is advantageous (e.g., see Figs. 9-10), the through-hole diameter or distance THD preferably is involved in the following: DP2 = D3 + [(THD - D2)/2] THD preferably includes values between D2 up to the D3 dimension, where the difference between THD and D2 ranges between 0 and up to D3 value. [0054] In certain example embodiments, the length of the tube end is determined by the volume of material required to seal the same thickness of material on the tube end as the tube wall diameter.

[0055] Fig. 6 is a cross-sectional schematic view demonstrating a first way in which a flanged pump-out tube 40 can be provided to a VIG unit subassembly to be sealed, in accordance with certain example embodiments. The Fig. 6 example VIG unit subassembly includes first and second substrates 60a and 60b, with a gap 62 therebetween that is to be evacuated to a pressure less than atmospheric. The second substrate 60b includes a recess 64 that can accommodate a getter material or the like, however, this need not be provided in different example embodiments. In brief, the VIG unit subassembly shows the tube 40 with a datum from the exterior pocket surface of the pocket 66 formed in the first substrate 60a, with no additional pocket being formed on the interior surface of the first subsrate 60a.

[0056] The flanged tube 66 is substantially internal to the VIG unit subassembly of Fig. 6 and in essence sits in a pocket 66 drilled or otherwise formed in the first substrate 60a. The tube 66 is held in place using frit 68, which is provided around the outmost flange 42 (and optionally between the flange’s lower surface and an upper surface of the pocket 66) and may be fired as per conventional approaches. However, the tube 40 itself does not protrude beyond the outer surface of the first substrate 60a once it is sealed, as the tube 40 is tipped off, causing the sidewall(s) thereof to collapse inwardly and drop below an outermost surface of the substrate 60a if it is not already seated therebelow. That is, in certain example embodiments, the unsealed tube 40 may protrude beyond an exterior major surface of the first substrate 60a and may not once it is sealed. In different example embodiments, the unsealed tube 40 will not protrude beyond the exterior major surface of the first substrate 60a before and after it is sealed.

[0057] The pocket 66 in which the skirt 42 of the tube 40 sits is advantageous because it allows more tube material to be exposed and used in forming the seal. The port in which the lower portion of the tube 40 is to sit may be formed by drilling a through-hole of a first diameter or major distance, and the pocket 66 may be formed by drilling a recess in the substrate proximate to the through-hole. This pocket or recess 66 is not a through-hole, otherwise it merely would serve as a larger (or supplementary) pump-out port. The through-hole and the recess may be formed in registration with one another, e.g., so that the approximate centers of each are substantially aligned (e.g., from plan view and/or cross-sectional perspectives, the latter of which can be appreciated from Fig. 6). The through-hole and the recess may be substantially circular in plan view in certain example embodiments, although other configurations are possible in different example embodiments.

[0058] The VIG unit subassembly shown in Fig. 6 is evacuated through the tube 40, which open to the interior air space or cavity, using a vacuum. A vacuum cup similar to that shown in Fig. 3 may be used in certain example embodiments, but it need not be used in all embodiments (e.g., in embodiments where the entire subassembly is processed in vacuum conditions). When sufficiently low pressure is reached, a laser or the like is used to seal the tube

40. The laser may be directed from the same side of the substrate as the side to be tipped off in certain example embodiments. This may promote sagging of the melted tube material until it eventually covers over the hole. In other words, laser exposure to the sidewall of the tube 40 will cause the side wall of the tube 40 to begin to sag inwardly. The laser may trace the sag as a bridge begins to form, hermetically sealing the tube 40.

[0059] In certain example embodiments, the glass substrate 60a preferably is sufficiently transparent to the wavelength of the laser so as avoid absorbing a significant amount of energy. The tube 40, by contrast, preferably is sufficiently opaque to that wavelength to absorb the energy and form the seal. In this sense, the tube 40 may be heated preferentially (e.g., compared to the first substrate 60a and/or the second substrate 60b) in certain example embodiments. Moreover, the portions of the tube 40 to be melted may be heated preferentially compared to the skirt 42, which also may be more transparent to the wavelength of the laser than that portion to be melted.

[0060] Additionally, in certain example embodiments, the heating may be preferential heating that includes a first or core heating phase to

substantially melt the tube (or sealing sidewall(s)), followed by a second phase that causes tube (or sealing sidewall(s)) to sag together and form the bridge. One or both of these phases may preferentially heat the tube (or sealing sidewall(s)) relative to the rest of the VIG unit subassembly including, for example, the overlying substrate. Laser heating may be used for either or both phases in different example embodiments. Although laser heating is mentioned herein, it will be appreciated that infrared (IR) heating may be used in connection with any heating procedure described herein. Preferential heating may be accomplished by ensuring that the composition of the tube and the glass substrates differ. The composition of the tube may be uniform or varied in different example embodiments. For example, the tube (or portions thereof) may have a higher iron content compared to the glass, e.g., so that the glass is less likely to absorb laser or other radiation. Additionally, or in the alternative, the skirt of the flanged tube may include a higher or lower iron content compared to other parts of the flanged tube. In certain example embodiments, the glass and the skirt will have the same or substantially the same absorption, and the part of the tube to be tipped off will have a higher absorption (e.g., based on differing iron contents).

[0061] Fig. 7 is a cross-sectional schematic view showing the Fig. 6 example VIG unit subassembly sealed in accordance with certain example embodiments. Fig. 7 thus shows the sealed tube 40’ including the bridge portion 44, which covers the pump-out port and helps provide a hermetic seal so that the cavity 62 can remain at vacuum. The bridge portion 44 protrudes no further than the outermost surface of the first substrate 60a.

[0062] Fig. 8 is a cross-sectional schematic view demonstrating a second way in which a flanged pump-out tube can be provided to a VIG unit subassembly to be sealed, in accordance with certain example embodiments. The Fig. 8 example shows a T-shaped flanged tube 40a provided to the substrate 42, which is the same example type of substrate shown in and described above in connection with Fig. 4. That is, the substrate 42 here includes upper and lower pockets 54a and 54b, and the tube 40a here is located from the interior pocket 54b surface. The sealing frit 68 is provided between an upper surface of the skirt of the flanged tube 40a and a surface of the interior or lower pocket 54b.

[0063] Fig. 9 is a cross-sectional schematic view showing the Fig. 8 example VIG unit subassembly sealed in accordance with certain example embodiments. Similar to Fig. 7 described above, here, the sealed tube 40a’ is recessed in, or at least flush with respect to, an outermost surface of the substrate 42. The bridge 44 is formed by melting the sidewall(s) of the tube with a laser or the like, hermetically sealing the unit. Advantageously, the laser or other energy source melting the tube 40a does not directly focus on the frit

68, which is provided around the outside of the tube 40a to be sealed. This helps in avoiding potential compromises to the seal that is formed.

[0064] It will be appreciated that the basic flanged tube design shown in and described in connection with Figs. 8-9 need not be used with a substrate having both upper and lower pockets 54a and 54b. In this regard, Fig. 10 is a cross-sectional schematic view showing an example VIG unit subassembly lacking a top pocket that has been sealed in accordance with certain example embodiments. In the Fig. 10 example, the sealed tube 40a’ is inserted into the pump-out port of the substrate 60a’, which includes an upper recess 54a but lacks a upper towards the outermost surface of the substrate 60a’. As can be appreciated from the Fig. 10 example, there is a space between an outer edge of the flanged tube and an inner wall(s) of the recess 54b, which can aid in accommodating additional frit material 68, allow for some thermal expansion / contraction during fusing of the tube to the substrate 60a and/or melting of the tube, etc. Although shown schematically and not to scale, it also will be appreciated from a comparison of Figs. 9-10 that the size of the pump-out port and recess(es) may be varied in different example embodiments, e.g., provided that the guidance above is used in certain example instances.

[0065] As also indicated above, when multiple pockets are provided, they need not have the same dimensions. Fig. 11, for example, is a cross- sectional schematic view showing an example VIG unit subassembly with top and bottom pockets 54a’ and 54b’ that has been sealed in accordance with certain example embodiments. That is, the first substrate 42’ includes top and bottom pockets 54a’ and 54b’ that have different diameters or major distances, and different lengths through the substrate 42’. Although the top pocket 54a’ is shown to be larger than the bottom pocket 54b’ in both of these dimensions, different example embodiments may change these relations. For example, the top pocket 54a’ may be smaller than the bottom pocket 54b’ in both of these dimensions, the top pocket 54a’ may be smaller than the bottom pocket 54b’ in the width but not length dimension, etc.

[0066] The machined pocket in the substrate that accommodates the flanged tube can be expanded to allow for insertion of a getter around the sealing tube, in certain example embodiments. For example, expansion areas can be provided around where the frit is to be provided. These expansion areas can be separately defined recesses in different example embodiments.

[0067] In certain example embodiments, the tube and sealing frit can be installed pre-tempering for construction of tempered VIG units. The sealing frit may be fired during the tempering process, which may allow for higher melting point frits to be used in obtaining a hermetic seal.

[0068] A profile / cross-section may be formed by creating a through- hole, and one or more channels or grooves around the through-hole, thereby defining the recess(es) or pocket(s). These features may be formed in any suitable manner such as, for example, by drilling into a substrate.

[0069] When viewed in cross-section, the recess(es) may be generally U- shaped, semi-circular, trapezoidal, and/or the like. Successive drilling operations may be performed to approximate these and/or other shapes, as well, e.g., in a more stepped manner.

[0070] When viewed in plan view, generally circular, ovular, square, rectangular, and/or other features may be used for the through-hole and/or recess in different example embodiments. For instance, generally square shaped, ovular, and/or other configurations, when viewed from a plan view, may be used in different example embodiments. It also will be appreciated that differently shaped features may be used in connection with a single

embodiment. For instance, when viewed from a plan view, an example embodiment may include a generally circular through-hole and a groove, channel, or recess that at its outer extent is generally square shaped, rectangular, etc. Similarly, when viewed from a plan view, an example embodiment may include a generally rectangular or square-shaped through- hole and a groove, channel, or recess that at its outer extent is generally circular, ovular, etc.

[0071] The techniques of U.S. Patent No. 9,371,683 (the entire contents of which are hereby incorporated herein by reference) may be used to seal the flanged tube, e.g., by tracing smaller and smaller circles or other connected patterns around the tube proximate to the sidewall(s) / sealing arm(s) so as to cause opposing edges of the sidewall(s) / sealing arm(s) to sag towards one another and form a bridge. In cases where multiple separate sidewalls / sealing arms are provided, progressive scans of narrower width may be used to similar effect. For instance, one or more lasers may be used to scan along first and second upwardly projecting sealing arms to cause them to sag towards one another. The laser(s) may be focused along scan lines or scan areas that are increasingly close to one another, e.g., as the sag continues to develop in the formation of the bridge.

[0072] Fig. 12 is a flowchart showing an example process for making a

VIG unit in connection with a flanged pump-out tube, in accordance with certain example embodiments. In step S1201, the port profile is formed in the first substrate, e.g., via one or more drilling operations or the like. That is, the through-hole and any pockets are formed in step S1201. Cutting, drilling, seaming, and/or other fabrication processes may be performed here. In step SI 203, frit material is applied to peripheral edges of the second substrate. Spacers or pillars are placed on the second substrate in step S1205. The flanged tube is affixed to the first substrate in step S1207. This may include, for example, applying frit to the flanged tube before and/or after it is located with respect to the substrate. The frit may be fired at this time to hermetically seal the flanged tube to the substrates. Alternatively, if the frit and tube are able to survive heat treatment (e.g., thermal tempering), the flanged tube may be applied to an annealed substrate that has had the port profile formed therein, and the substrate may be heat treated together with the flanged tube so that the associated hermetic seal is formed together in one process.

[0073] The first and second substrates are booked together in step SI 209 so that a cavity is formed therebetween, and a hermetic edge seal is formed in step S1211 (e.g., via laser heating, heating in an oven, using infrared heaters, and/or the like). The cavity is evacuated to a pressure less than atmospheric in step S 1213.

[0074] The flanged tube optionally is pre-heated in step S1215, e.g., while maintaining the vacuum. This may be accomplished using an oven, using infrared heaters, via a laser, etc. Core heating is performed in step S1217, and chase heating is performed in step S1219 repeatedly until the tube is sealed (e.g., as indicated in step S1221). The core heating process of step S1217 provides the bulk of the melting process, whereas the chase heating of step S1219 is provided at progressively smaller circumferences, areas, and/or the like, e.g., depending on the configuration of the tube, sidewall(s) / sealing arm(s), the through-hole, the developing sag, etc. Once sealed, the unit may be moved for further processing in step S1223.

[0075] As will be appreciated from the above, certain example embodiments may make use of a hermetic sealing material (e.g., a metal solder) that can withstand the VIG processing temperatures and can be placed into a VIG subassembly to help seal the pump-out port from within. The solder may be sufficiently shaped to allow gasses to evacuate through the port in certain example embodiments. For instance, a solder or other preform may be applied around the outside of the flange, between the flange and the substrate, and/or elsewhere, in different example embodiments. This preform may be fired and thus used to hermetically seal the flanged tube to the substrate in certain example embodiments.

[0076] In certain example embodiments, a secondary seal may be provided proximate to the sealed flanged tube. This secondary seal may be formed form a more pliable material such as resin or the like and may help further protect the tube in some instances. The secondary seal may simply occupy any space that in an outer recess that is not covered by the bridge, e.g., such that the outer surface of the VIG unit is flush or substantially flush across its entire width.

[0077] Fig. 13 is a flowchart showing another example process for making a VIG unit in connection with an internal seal, in accordance with certain example embodiments.

[0078] Fig. 13 is a flowchart showing another example process for making a VIG unit in connection with an internal seal, in accordance with certain example embodiments. Fig. 13 is similar to Fig. 12 in many respects. For example, in step S 1201, the pump-out port profile is formed in the first substrate, e.g., via one or more drilling operations or the like. The flanged tube with the frit is affixed the first substrate in step SI 301, using a bismuth or other suitable frit. This frit material is able to withstand heat treatment such as thermal tempering, so the affixed flanged tube and the first substrate are tempered together. After that, the steps are performed as above.

[0079] It will be appreciated that the steps in the Fig. 12 and Fig. 13 example processes may be performed in any suitable order, by different parties, and/or that further steps may be provided in different example embodiments. For instance, different parties may form the hole compared to parties who make the tube, seat the tube in the hole, seal the VIG and/or port, etc. In certain example embodiments, a tube profile will be formed in the first substrate, the first and/or second substrate may be tempered, frit may be applied to the peripheral edges of the first and/or second substrate, spacers may be placed, and then other operations may be performed, e.g., as shown in these drawings.

[0080] Any suitable laser may be used for sealing. For example, a 1064 nm wavelength laser operating at 10-30 watts, more preferably 20-30 watts may be used. With such lasers and diameters, it has been found that tubes may be sealed by firing through float glass and that about 10-30% more energy is required compared to sealing the tubes unobstructed. The increase may be provided in time and/or power in different example embodiments.

[0081] It will be appreciated that techniques disclosed herein may be used in a wide variety of applications including for example, in VIG window applications, merchandizers, laminated products, hybrid VIG units (e.g., units where a substrate is spaced apart from a VIG unit via a spacer system), etc.

[0082] The terms“heat treatment” and“heat treating” as used herein mean heating the article to a temperature sufficient to achieve thermal tempering and/or heat strengthening of the glass inclusive article. This definition includes, for example, heating a coated article in an oven or furnace at a temperature of at least about 550 degrees C, more preferably at least about 580 degrees C, more preferably at least about 600 degrees C, more preferably at least about 620 degrees C, and most preferably at least about 650 degrees C for a sufficient period to allow tempering and/or heat strengthening. This may be for at least about two minutes, or up to about 10 minutes, in certain example embodiments. These processes may be adapted to involve different times and/or temperatures.

[0083] As used herein, the terms“on,”“supported by,” and the like should not be interpreted to mean that two elements are directly adjacent to one another unless explicitly stated. In other words, a first layer may be said to be “on” or“supported by” a second layer, even if there are one or more layers therebetween.

[0084] In certain example embodiments, a method of making a VIG unit is provided. There are provided first and second glass substrates. The first substrate includes a hole formed therein, with the hole being formed to have first and second portions, with the first portion being closer to an outer surface of the first substrate than the second portion, with the first portion having a first width across the first substrate and the second portion having a second width across the first substrate, and with the first width being wider than the second width, the first and second portions together forming a through-hole through the first substrate. A flanged pump-out tube including a skirt intermediate upper and lower portions is placed in the hole, such that the lower portion of the tube extends into the second portion and the upper portion of the tube is located in the first portion. The first and second substrates are sealed together in connection with an edge seal provided around peripheral edges of the first and/or second substrates, with a cavity being defined by the first and second substrates, and with a plurality of spacers being provided between the first and second substrates in the cavity and helping to maintain the first and second substrates in substantially parallel, spaced-apart relation to one another. The cavity is evacuated to a pressure less than atmospheric. The pump-out tube is heated so as to cause at least a part of the upper portion of the tube to collapse inwardly upon itself, covering the second width and hermetically sealing the VIG unit and forming a sealed tube, the sealed tube being flush with, or partially recessed with respect to, an outermost surface of the first substrate.

[0085] In addition to the features of the previous paragraph, in certain example embodiments, the first and second portions of the hole may be formed by drilling.

[0086] In addition to the features of either of the two previous paragraphs, in certain example embodiments, the pump-out tube may be sealed to the first substrate using frit material provided to the pump-out tube and/or the first substrate.

[0087] In addition to the features of the previous paragraph, in certain example embodiments, the frit material may seal the skirt to the first substrate.

[0088] In addition to the features of either of the two previous paragraphs, in certain example embodiments, the frit material may seal outer peripheral edges of the skirt to the first substrate.

[0089] In addition to the features of any of the three previous

paragraphs, in certain example embodiments, frit material may or may not be provided to an underside of the skirt.

[0090] In addition to the features of any of the four previous paragraphs, in certain example embodiments, frit material may be provided to the pump-out tube prior to the tube being placed in the hole.

[0091] In addition to the features of any of the seven previous paragraphs, in certain example embodiments, the heating may be laser heating.

[0092] In addition to the features of any of the eight previous

paragraphs, in certain example embodiments, the laser heating may be practiced so as to preferentially heat the pump-out tube relative to the first substrate and/or the skirt.

[0093] In addition to the features of any of the nine previous paragraphs, in certain example embodiments, the laser heating may include tracing collapsing portions of the tube, e.g., as the tube collapses inwardly upon itself in forming the sealed tube.

[0094] In certain example embodiments, a method of making a VIG unit subassembly is provided. The method includes providing a first glass substrate including a hole formed therein, with the hole being formed to have first and second portions, with the first portion being closer to an outer surface of the first substrate than the second portion, with the first portion having a first width across the first substrate and the second portion having a second width across the first substrate, and with the first width being wider than the second width, the first and second portions together forming a through-hole through the first substrate. The first substrate is forwarded to another party to: place in the hole a flanged pump-out tube including a skirt intermediate upper and lower portions such that the lower portion of the tube extends into the second portion and the upper portion of the tube is located in the first portion; seal together the first glass substrate with a second substrates in connection with an edge seal provided around peripheral edges of the first and/or second substrates, a cavity being defined by the first and second substrates, and a plurality of spacers being provided between the first and second substrates in the cavity and helping to maintain the first and second substrates in substantially parallel, spaced-apart relation to one another; evacuate the cavity to a pressure less than atmospheric; and laser heat the pump-out tube so as to cause at least a part of the upper portion of the tube to collapse inwardly upon itself, covering the second width and hermetically sealing the VIG unit and forming a sealed tube, the sealed tube being flush with, or partially recessed with respect to, an outermost surface of the first substrate.

[0095] In addition to the features of the previous paragraph, in certain example embodiments, the first and second portions of the hole may be formed by drilling.

[0096] In addition to the features of either of the two previous paragraphs, in certain example embodiments, the pump-out tube may be sealed to the first substrate using frit material provided to the pump-out tube and/or the first substrate.

[0097] In addition to the features of any of the three previous

paragraphs, in certain example embodiments, the frit material may seal the skirt to the first substrate.

[0098] In addition to the features of any of the four previous paragraphs, in certain example embodiments, the frit material may seal outer peripheral edges of the skirt to the first substrate. [0099] Certain example embodiments relate to a VIG unit made by the method of any one of the 15 previous paragraphs.

[00100] In certain example embodiments, a VIG unit is provided. First and second glass substrates are maintained in substantially parallel, spaced apart relation to one another via a hermetic edge seal and a plurality of spacers disposed in a cavity defined between the first and second glass substrates. The cavity is evacuated to a pressure less than atmospheric using a pump-out port formed in the first substrate that has been hermetically sealed with a laser- sealed flanged tube. The laser-sealed tube includes a sealing portion made therefrom proximate to the cavity, with the laser-sealed tube being located internal to the VIG unit without protruding thereform.

[00101] In addition to the features of the previous paragraph, in certain example embodiments, the tube may be connected to the first substrate of the VIG unit via frit material.

[00102] In addition to the features of either of the two previous paragraphs, in certain example embodiments, the frit material connecting the tube to the first substrate may be provided around a skirt of the tube.

[00103] In addition to the features of any of the three previous paragraphs, in certain example embodiments, the tube may include a skirt and a lower portion, the skirt being intermediate the sealing portion and the lower portion of the tube, the lower portion of the tube extending towards the cavity.

[00104] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.