Flanged tube for evacuation and hermetic sealing of vacuum insulating glass (VIG) units, VIG units including flanged tubes, and related methods

Abstract

Certain exemplary embodiments of the present invention relate to a vacuum insulating glass (VIG) unit and / or a method for making the same. A sealing tube or sealing material is provided within the VIG unit, thereby potentially eliminating the need for a protective cap and allowing greater flexibility in handling, frame design, hybrid VIG construction, stacking, and the like. In at least certain exemplary embodiments, the sealing tube can be relocated to an interior area within a recessed pocket in the substrate. The VIG unit is free of protruding pump-out tubes or the like.

Description

[Technical field]

[0001] Certain exemplary embodiments of the present invention relate to vacuum insulated glass (VIG) units and / or methods of making same, and more particularly, certain exemplary embodiments of the present invention relate to flanged pump-out tubes for evacuation and hermetic sealing of VIG units, VIG unit subassemblies including pump-out tubes, VIG units made using flanged pump-out tubes, and / or related methods. [Background technology]

[0002] A vacuum insulating glass (VIG) unit typically includes at least two spaced apart glass substrates that enclose a vacuum or low pressure space / cavity between them. The substrates are interconnected by a perimeter seal and typically include a spacer between the glass substrates to maintain the spacing between the substrates and to avoid collapse of the glass substrates that may be caused by the low pressure environment present between the substrates. Some exemplary 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 incorporated herein by reference in their entireties.

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

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

[0005] A VIG unit with a fused solder glass perimeter seal 4 is typically fabricated by depositing a glass frit in a solution (e.g., frit paste) around the perimeter of substrate 2 (or on substrate 3). This glass frit paste will eventually form the glass solder edge seal 4. Another substrate (e.g., 3) is then lowered onto substrate 2 such that the spacers / pillars 5 and glass frit solution are sandwiched between the two substrates 2, 3. The entire assembly including glass substrates 2, 3, spacers / pillars 5, and seal material (e.g., glass frit in solution or paste) is then heated to a temperature of at least about 500° C., at which point the glass frit melts and wets the surfaces of the glass substrates 2, 3, eventually forming the hermetic perimeter / edge seal 4.

[0006] After formation of the edge seal 4 between the substrates, a vacuum is pulled via a pump-out tube 8 to form a low pressure space / cavity 6 between the substrates 2, 3. The pressure in the space 6 is below atmospheric pressure, for example, about 10 -2A vacuum process down to levels below Torr may be produced. The substrates 2, 3 are hermetically sealed to maintain a low pressure within the space / cavity 6. Small high strength spacers / pillars 5 are provided between the substrates to maintain a nearly parallel separation of the substrates relative to atmospheric pressure. As mentioned above, once the space 6 between the substrates 2, 3 has been 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 involves inserting a pre-formed glass pump-out tube 8 into an aperture / hole 10 that has been pre-formed (e.g., by drilling) in one of the glass substrates 2. After the pump-out tube 8 is seated in the aperture / hole 10, an adhesive frit paste is typically applied to the pump-out tube 8 in the area near the opening of the hole 10 adjacent the outer surface of the glass substrate 2. As mentioned above, the pump-out tube may be sealed after evacuation or purging of the VIG unit cavity.

[0008] After evacuating the cavity to a subatmospheric pressure, sealing of the pump-out tube may be accomplished by heating the end of the pump-out tube used to evacuate or purge the cavity to melt the opening, thus sealing 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] Sometimes, the pump-out tube may not seat properly in the hole formed in the glass substrate. As a result, the pump-out tube may tilt or be tilted to one side and therefore not 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 seated improperly and at an undesirable angle to the surface of the glass substrate, it may be difficult to properly seal the pump-out tube because the laser may not be able to consistently melt the tip of the pump-out tube, for example, due to differences in distance between various portions of the tilted pump-out tube top and the laser source. Consistent melting of the top of the pump-out tube may result in an incomplete seal and therefore air leakage, which may occur quickly or more slowly over time depending on the quality of the seal. Additionally, based on the degree of tilt or tilt of the tube, the laser may hit the tube wall instead of the top. If the laser hits the tube wall, it may potentially bypass the tube and hit the frit, thereby damaging the frit and causing undesirable outgassing into the cavity.

[0010] It would seem desirable to provide a way to seat the pump-out tube in the hole and reduce the amount of tube tilt to an acceptable level. Attempts have been made to improve the vacuum and / or tip-off process in this regard. See, for example, U.S. Pat. Nos. 9,371,683 and 8,833,105 and U.S. Patent Application Publication No. 2013 / 0306222, the contents of which are incorporated herein by reference in their entirety. Such techniques are advantageous compared to conventional approaches. Moreover, the inventors of the present application recognize that further improvements are still possible.

[0011] For example, the pump-out tube, even when properly oriented relative to the substrate, still protrudes outward from the outermost surface of the VIG unit. If the sealed tube is pushed, knocked loose, or broken in whole or in part, the VIG unit may lose vacuum faster than would otherwise be desirable. Caps are sometimes provided over the protruding sealed tube to help protect against impacts that could cause breakage, etc., but such caps have limited effectiveness against heavy mechanical forces and add additional processing steps and materials to the VIG unit manufacturing process.

[0012] This conventional configuration is shown more fully in FIG. 3, which is a cross-sectional schematic of a VIG unit with a sealed pump-out tube 8 protruding outwardly from the VIG unit and protected using a cap 15. The pump-out port is used to allow a vacuum path when evacuating and subsequently sealing the VIG unit. Conventionally, this port is sealed by inserting the tube 8, which has 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. The protective cap 15 is attached to the glass surface via adhesive tape 16 or other means that helps protect the delicate tube 8 protruding from the glass surface.

[0013] It can therefore be appreciated that it would be desirable to entirely eliminate the need for a pump-out tube protruding outwardly from the outermost surface of the VIG unit and / or its cap. Summary of the Invention

[0014] One aspect of certain exemplary embodiments relates to the use of a pump-out tube inside the VIG unit. In certain exemplary embodiments, there is no need for a pump-out tube to protrude outward from the outermost surface of the VIG unit. This arrangement in certain exemplary cases simplifies the manufacturing process, for example, by eliminating the need to provide and seal a separate cap, and by reducing the need for care by eliminating a very fragile element of the VIG unit, facilitating shipping, handling, transportation, and / or other processing operations. Frame design, lamination, IG construction, and / or the like can also be simplified.

[0015] Another aspect of certain exemplary embodiments relates to sealing of the flanged pump-out tube such that the sealed tube does not protrude beyond the outermost surface of the VIG unit (e.g., flush with or internal to the VIG unit). This configuration is advantageous in certain exemplary instances, since it can reduce and sometimes eliminate the need for a separate protruding protective cap placed over the tube. Removal of the protective cap can then be advantageous from an aesthetic standpoint. Moreover, removal of the protective cap can be advantageous from the standpoint of reducing the possibility of damage to the VIG unit and making shipping, handling, transport, and / or other processing operations easier. With regard to the former, as mentioned above, bumping the cap can translate forces into the sealing tube, which can cause the cap to move and / or break, compromising the vacuum quality of the VIG. With regard to the latter, since the cap is absent, it can be possible to avoid the need to use special shipping and / or packaging materials to accommodate such caps.

[0016] Another aspect of certain exemplary embodiments includes a redesigned VIG pump out port and / or tubing that advantageously improves vulnerability associated with shear loads and / or the like, for example, by eliminating tubing that extends beyond the outermost plane of the VIG unit.

[0017] In a particular exemplary embodiment, a method of making a VIG unit is provided. A first glass substrate and a second glass substrate are provided. The first substrate includes a hole formed in the first substrate, the hole being formed to have a first portion and a second portion, the first portion being closer to an outer surface of the first substrate than the second portion, the first portion having a first width across the first substrate, the second portion having a second width across the first substrate, the first width being wider than the second width, and 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 disposed within the hole, such that a lower portion of the tube extends into the second portion and an upper portion of the tube is located within the first portion. The first and second substrates are sealed together with an edge seal around the periphery of the first and / or second substrates, a cavity defined by the first and second substrates, and a number of spacers disposed within the cavity between the first and second substrates and helping to maintain the first and second substrates in a substantially parallel spaced apart relationship with respect to one another. The cavity is evacuated to a pressure below atmospheric pressure. The pump-out tube is heated such that at least a portion of an upper portion of the tube collapses inwardly onto itself, covering the second width and sealing the VIG unit to form a sealed tube, the sealed tube being flush with or partially recessed relative to the outermost surface of the first substrate.

[0018] In certain exemplary embodiments, a method of making a VIG unit subassembly is provided, the method including providing a first glass substrate including a hole formed therein, the hole being formed to have a first portion and a second portion, the first portion being closer to an outer surface of the first substrate than the second portion, the first portion having a first width across the first substrate and the second portion having a second width across the first substrate, the first width being greater than the second width, and the first and second portions together forming a through hole through the first substrate. The first substrate is transferred to another batch, a flanged pump-out tube including a skirt intermediate an upper portion and a lower portion is placed in the hole such that a lower portion of the tube extends into the second portion and an upper portion of the tube is placed in the first portion, the first glass substrate and the second glass substrate are sealed to one another in association with an edge seal provided around a periphery of the first substrate and / or the second substrate, a cavity is defined by the first substrate and the second substrate, a plurality of spacers are provided within the cavity to support the first substrate and the second substrate. A cavity disposed therebetween and assisting in maintaining the first and second substrates in a substantially parallel spaced apart relationship from one another is evacuated to a pressure less than atmospheric pressure and the pump-out tube is laser heated, thereby causing at least a portion of an upper portion of the tube to collapse inwardly onto itself, covering the second width and hermetically sealing the VIG unit to form a sealed tube, the sealed tube being either flush with or partially concave relative to the outermost surface of the first substrate.

[0019] In a particular exemplary embodiment, a VIG unit is provided. A first glass substrate and a second glass substrate are maintained in a substantially parallel spaced relationship with each other via a hermetic edge seal and a number of spacers disposed in a cavity defined between the first glass substrate and the second glass substrate. The cavity is evacuated to a pressure lower than atmospheric pressure using a pump-out port formed in the first substrate hermetically sealed with a laser-sealed flanged tube. The laser-sealed tube includes a seal portion made therefrom adjacent to the cavity, and the laser-sealed tube is disposed inside the VIG unit without protruding therefrom.

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

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

[0022] [Figure 1] 1 is a cross-sectional schematic diagram of a conventional vacuum insulating glass (VIG) unit.

[0023] [Diagram 2] FIG. 1 is a top view of a conventional VIG unit.

[0024] [Diagram 3] FIG. 1 is a cross-sectional schematic diagram of a VIG unit with a sealed pump-out tube protruding outward from the VIG unit and protected using a cap.

[0025] [Figure 4] 1 is a cross-sectional schematic view of a flanged tube that may be used in certain exemplary embodiments. FIG.

[0026] [Diagram 5]1A-1C are cross-sectional schematic diagrams illustrating example substrate designs that may be used in certain example embodiments.

[0027] [Figure 6] 1A-1C are cross-sectional schematic diagrams illustrating a first way in which a flanged pump-out tube may be provided to a sealed VIG unit subassembly, according to certain exemplary embodiments.

[0028] [Figure 7] FIG. 7 is a cross-sectional schematic diagram illustrating the exemplary VIG unit subassembly of FIG. 6 sealed in accordance with certain exemplary embodiments.

[0029] [Figure 8] 11 is a cross-sectional schematic diagram illustrating a second way in which a flanged pump-out tube may be provided to a sealed VIG unit subassembly, according to certain exemplary embodiments. FIG.

[0030] [Figure 9] FIG. 9 is a cross-sectional schematic diagram illustrating the exemplary VIG unit subassembly of FIG. 8 sealed in accordance with certain exemplary embodiments.

[0031] [Figure 10] FIG. 2 is a cross-sectional schematic diagram illustrating an exemplary VIG unit subassembly lacking a sealed upper pocket in accordance with certain exemplary embodiments.

[0032] [Figure 11] 1 is a cross-sectional schematic diagram illustrating an exemplary VIG unit subassembly having sealed upper and lower pockets in accordance with certain exemplary embodiments.

[0033] [Figure 12] FIG. 1 is a flow diagram illustrating an exemplary process for making a VIG unit associated with a flanged pump-out tube, according to certain exemplary embodiments.

[0034] [Figure 13] FIG. 13 is a flow diagram illustrating another exemplary process for making a VIG unit in conjunction with an internal seal, according to certain exemplary embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] Certain exemplary embodiments relate to improved techniques for evacuating vacuum insulating glass (VIG) units. More specifically, certain exemplary embodiments of the present invention relate to flanged pump-out tubes for evacuation and hermetically sealing VIG units, VIG unit subassemblies including pump-out tubes, VIG units made using flanged pump-out tubes, and / or related methods. Typically, the interior space of a VIG unit is evacuated through a surface-mounted tube or other structure that facilitates sealing once the interior space reaches a sufficiently low pressure. That tube or other structure protrudes from the surface even when sealed, and is usually protected by a protective cap, but nevertheless requires special handling. Certain exemplary embodiments improve upon this approach by using a flanged sealing tube with a truncated tip such that its top does not protrude beyond the outermost surface of the VIG unit, thereby potentially eliminating the need for a protective cap and allowing additional freedom in handling, frame design, hybrid VIG construction, lamination, etc. In essence, the flanged sealing tube is relocated to the interior surface within a recessed pocket, at least in certain exemplary embodiments.

[0036] In certain exemplary embodiments, the sealed tube is flush with or recessed against the outer surface of the glass of the VIG. As a result, a protective cap does not need to be applied above it. This in turn can result in easier processing, especially for secondary processes such as lamination, hybrid VIG manufacturing, etc. In addition, the elimination of the outer tube protruding outward from the substrate can allow improvements to be realized in shipping techniques, for example, where additional packing dunnage does not need to be provided to properly space the VIG units to account for the extra protrusion. Standard or more standard packaging, etc. can be used in certain exemplary embodiments.

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

[0038] The exemplary flange of Figure 4 includes a cylindrical or other hollow shaped tube 40 with a protruding feature 42 along its length L4. In the example of Figure 4, the tube 40 has an inner diameter or inner distance D1 and an outer diameter or outer distance D2 with a tube wall defined therebetween. Also in the example of Figure 4, the protruding feature 42 is intermediate the upper and lower ends of the tube 40, e.g., spaced a first distance L1 from the upper end of the tube 40 and a second distance L3 from the lower end of the tube 40, and has a length or thickness of L2. The protruding feature 42 has a diameter or major distance D3.

[0039] The protruding feature 42 functions as a flange and provides some potential processing improvements as well as product improvements, as will be more fully understood from the description provided below. The tube 40, in certain exemplary embodiments, is formed as a unitary piece. For example, in certain exemplary embodiments, the body of the tube 40 and the protruding feature 42 are both formed from the same material (e.g., glass). In certain exemplary embodiments, the tube 40 and the protruding feature 42 may be considered to be unitary 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 be part of a VIG unit subassembly. The tube 40 is hermetically sealed to the glass substrate in the 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 can be cylindrical or of another shape. 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 DP1 and DP2, respectively. The substrate has a thickness ST, and the recesses 54a-54b have depths P1 and P2, respectively. As described in more detail below, different embodiments can include an upper recess 54a, a lower recess 54b, or both recesses 54a-54b.

[0041] The sealing frit can be applied along the outermost diameter of the tube (e.g., as shown in FIG. 6) and / or can be applied between the top or bottom surface and the surface of the pocket between flange diameters D2 and D3 (see, e.g., FIG. 8). The flange feature allows the frit to be coated against a laser used in sealing the tube (e.g., as in the example of FIG. 8) and / or moved out of the laser path (e.g., as in the example of FIG. 6). Locating the frit away from the laser and / or in a location that is shielded from the laser can be advantageous since exposure of the frit to the laser can promote defects in the seal, tube sealing issues, haze buildup, and / or other issues in processing the VIG unit.

[0042] The flange features act as vertical stops and help maintain a vertical or substantially vertical relationship between the tube ends and the glass surface.

[0043] When the flange is provided on the inner VIG unit surface, thermal insulation can be provided. This thermal insulation advantageously allows for proper sealing of the tube. As a result, a gap can 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. This clearance can be close to zero and up to within about 1 mm of the outer diameter or distance D3 of the tube assembly. The lower pocket facilitates centering of the tube. Although not necessarily required for sealing in this configuration, an upper pocket may nevertheless be desirable for testing or other purposes.

[0044] The flange feature, when used as a datum from the exterior pocket surface, allows VBZ-based (vanadium, barium, and zinc-based) or other frits to be used in both the edge sealing and tube connection processes. This advantageously allows one common material to be used in multiple locations. Exemplary VBZ-based and / or other frits that may be used in connection with certain exemplary 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 incorporated herein by reference.

[0045] The flange feature, when used as a reference on an internal pocket surface (e.g., surface 2 or surface 3 of the resulting VIG unit), allows for the tube to be fired during tempering and utilizes a bismuth or other frit seal, reducing vulnerability to condensation water to which some VBZ systems and / or other frits are susceptible.

[0046] Lengths L1 and L3 do not need to be symmetrical and can be zero values ​​(e.g., L3=0.00 mm as shown in FIG. 8). However, if L1 and L3 are symmetrical, the installation operation may be facilitated through easier and more reliable orientation of the tube relative to the pump-out port.

[0047] In certain exemplary embodiments, the skirt or protruding feature thickness L2 can range from 0.30 mm to half the substrate ST, resulting in a smaller thickness remaining from the sealing operation (typically up to 0.75 mm). In certain exemplary embodiments where it is desired to heat treat (e.g., heat temper) the substrate to accommodate the flanged pump-out tube, the total glass that can be removed within the pocket depths P1 and P2 is at most half the total thickness of the substrate. In some cases, removing more glass may be incompatible with high temperature tempering, etc. Thus, in certain exemplary embodiments: L2={0.30mm~[(ST / 2)-0.75mm]} P1+P2≦(ST / 2) P1 does not have to be equal to P2

[0048] For the top or outer pocket flange standard, when sealing from the outside, the sum of the skirt L2 thickness and the final tube length is preferably no greater than half the substrate thickness. This helps ensure that the tube does not extend outward from the outermost surface of the VIG unit. Thus, in a particular exemplary embodiment:

[0049] L2+0.75≦(ST / 2), L2+0.75=P1

[0050] For the lower or inner pocket flange reference, the overall tube length L4 is preferably equal to or less than the thickness of the substrate plus 0.75 mm, and the depth of the pocket P1 is preferably equal to a minimum of 0.75 mm. The thickness of the flange is within the above range, remaining less than or equal to half the substrate thickness, allowing a maximum of 0.200 mm of sealing frit material when bonded to the pocket (see FIG. 8). Thus, in certain exemplary embodiments: (ST-0.200mm)≦L4≦ST+0.75mm P1≧0.75mm P2+P1≦ST / 2 P2 = (ST / 2) - P1 - 0.200 P2=L2+0.200

[0051] The flange diameter or distance is preferably at least 1 mm larger than the outer tube end diameter or distance and at least 2 mm smaller than the pocket diameter or distance in which the flange sits, allowing space for excess material and / or space for the edge of the flange to be sealed to the substrate.

[0052] In certain exemplary embodiments, the outer diameter or distance of the tube end is preferably 2 mm or less than the diameter of the inner tube end. This arrangement advantageously allows the tip of the tube to be efficiently ablated using a laser. Thus, in certain exemplary embodiments: D3-D2≧1.00mm D3≦(DP1 or DP2-2.00mm), DP1 or DP2 depends on the pocket to be inserted. D2-D1≦2.00mm D1≧0.50mm

[0053] Where thermal insulation is advantageous (see, e.g., Figures 9-10), THD, which is the diameter or distance of the through holes, is preferably set such that DP2 = D3 + [(THD - D2) / 2]. THD preferably includes values ​​between D2 and up to D3 dimensions, where the difference between THD and D2 ranges from 0 to the maximum D3 value.

[0054] In certain exemplary embodiments, the length of the tube end is determined by the volume of material required to seal onto the tube end a thickness of material equal to the tube wall diameter.

[0055] FIG. 6 is a cross-sectional schematic diagram illustrating a first method, in which a flanged pump-out tube 40 may be provided in a sealed VIG unit subassembly according to a particular exemplary embodiment. The exemplary VIG unit subassembly of FIG. 6 includes a first substrate 60a and a second substrate 60b with a gap 62 therebetween that is evacuated to a pressure less than atmospheric pressure. The second substrate 60b includes a recess 64 that may accommodate a getter material, etc., although this need not be provided in different exemplary embodiments. In brief, the VIG unit subassembly shows a tube 40 with a reference from an outer pocket surface of a pocket 66 formed in the first substrate 60a, and does not include an additional pocket formed on the inner surface of the first substrate 60a.

[0056] The flanged tube 66 is substantially inside the VIG unit subassembly of FIG. 6 and essentially sits in a pocket 66 drilled or otherwise formed in the first substrate 60a. The tube 66 is held in place using a frit 68, which is provided around the outermost flange 42 (and optionally between the underside of the flange and the upper surface of the pocket 66) and can be fired according to conventional techniques. However, the tube 40 itself does not protrude beyond the outer surface of the first substrate 60a when sealed, and when the tube 40 is tipped off, its sidewalls collapse inward and drop below the outermost surface of the substrate 60a if not already seated thereunder. That is, in certain exemplary embodiments, the unsealed tube 40 may protrude beyond the outer major surface of the first substrate 60a and may not protrude when sealed. In different exemplary embodiments, the unsealed tube 40 does not protrude beyond the outer major surface of the first substrate 60a before or 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 sits can be formed by drilling a through hole of a first diameter, or major distance, and the pocket 66 can be formed by drilling a recess in the substrate proximate the through hole. This pocket or recess 66 is not a through hole, but rather simply serves as a larger (or auxiliary) pump-out port. The through hole and recess can be formed, for example, in registration with one another such that their approximate centers are substantially aligned (e.g., from a plan view and / or a cross-sectional view perspective, the latter of which can be seen in FIG. 6). The through hole and recess can be substantially circular in plan view in certain exemplary embodiments, although other configurations are possible in different exemplary embodiments.

[0058] The VIG unit subassembly shown in FIG. 6 is evacuated using a vacuum through the tube 40, which opens to an interior air space or cavity. A vacuum cup similar to that shown in FIG. 3 may be used in certain exemplary embodiments, but need not be used in all embodiments (e.g., in embodiments in which the entire subassembly is processed under vacuum). Once a sufficiently low pressure is reached, a laser or the like is used to seal the tube 40. In certain exemplary embodiments, the laser can be directed from the same side of the substrate as the side that is being tipped. This can encourage the molten tube material to sag until it eventually covers the top of the hole. In other words, exposure of the laser to the sidewall of the tube 40 causes the sidewall of the tube 40 to begin to sag inward. The laser can trace the sag as a bridge begins to form, hermetically sealing the tube 40.

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

[0060] Moreover, in certain exemplary embodiments, the heating may be preferential heating, including a first or core heating stage to substantially melt the tubes (or sealed sidewalls), followed by a second stage to cause the tubes (or sealed sidewalls) to sag together and form a bridge. Either or both of these stages may, for example, preferentially heat the tubes (or sealed sidewalls) relative to the remainder of the VIG unit subassembly, including the overlying substrate. Laser heating may be used for either or both stages in different exemplary embodiments. Although laser heating is referred to herein, it will be understood that infrared (IR) heating may be used in connection with any of the heating procedures described herein. Preferential heating may be achieved by ensuring that the compositions of the tube and the glass substrate are different. The composition of the tube may be uniform or varied in different exemplary embodiments. For example, the tube (or a portion thereof) may have a higher iron content compared to the glass, such that, for example, the glass is less likely to absorb laser or other radiation. Additionally or alternatively, the skirt of the flanged tube may have a higher or lower iron content compared to other portions of the flanged tube, in certain exemplary embodiments, the glass and skirt have the same or substantially the same absorbency, and the portion of the tube that is to be tipped has a higher absorbency (e.g., based on a different iron content).

[0061] Figure 7 is a cross-sectional schematic diagram illustrating the exemplary VIG unit subassembly of Figure 6 sealed in accordance with certain exemplary embodiments. Thus, Figure 7 shows a sealed tube 40' that includes a bridge portion 44 that covers the pump-out port and helps provide a hermetic seal so that the cavity 62 can maintain a vacuum. The bridge portion 44 does not protrude farther than the outermost surface of the first substrate 60a.

[0062] Figure 8 is a cross-sectional schematic diagram illustrating a second way in which a flanged pump-out tube may be provided to a sealed VIG unit subassembly, according to certain exemplary embodiments. The example of Figure 8 shows a T-shaped flanged tube 40a provided to a substrate 42, which is the same exemplary type of substrate illustrated and described above in connection with Figure 4, namely, where the substrate 42 includes an upper pocket 54a and a lower pocket 54b, where the tube 40a is positioned from the inner pocket 54b surface. A sealing frit 68 is provided between the upper surface of the skirt of the flanged tube 40a and the surface of the inner or lower pocket 54b.

[0063] Figure 9 is a cross-sectional schematic diagram showing the exemplary VIG unit subassembly of Figure 8 sealed in accordance with certain exemplary embodiments. Similar to Figure 7 above, the sealed tube 40a' here is recessed into or at least flush with the outermost surface of the substrate 42. The bridge 44 is formed by melting the sidewalls of the tube with a laser or the like to hermetically seal the unit. Advantageously, the laser or other energy source that melts the tube 40a is not directly focused on the frit 68 provided around the outside of the tube 40a being sealed. This helps to avoid potential defects in the seal that is formed.

[0064] It will be appreciated that the basic flanged tube design illustrated and described in connection with FIGS. 8-9 need not be used with a substrate having both an upper pocket 54a and a lower pocket 54b. In this regard, FIG. 10 is a cross-sectional schematic diagram illustrating an exemplary VIG unit subassembly lacking a sealed upper pocket in accordance with certain exemplary embodiments. In the example of FIG. 10, the sealed tube 40a' is inserted into a pump-out port of a substrate 60a', which includes an upper recess 54a, but not upward toward the outermost surface of the substrate 60a'. As can be seen from the example of FIG. 10, there is a space between the outer edge of the flanged tube and the inner wall of the recess 54b, which can help accommodate additional frit material 68, can allow for some thermal expansion / contraction during fusing of the tube to the substrate 60a, and / or melting of the tube, etc. Although shown diagrammatically and not to scale, it will also be understood from a comparison of Figures 9-10 that the sizes of the pump-out ports and recesses may vary in different exemplary embodiments, for example, when the guidance above is used in a particular exemplary case.

[0065] As also shown above, when multiple pockets are provided, they need not have the same dimensions. FIG. 11 is a cross-sectional schematic diagram illustrating an exemplary VIG unit subassembly with an upper pocket 54a' and a lower pocket 54b' sealed in accordance with certain exemplary embodiments. That is, a first substrate 42' includes an upper pocket 54a' and a lower pocket 54b' having different diameters or major distances and different lengths through the substrate 42'. Although the upper pocket 54a' is shown larger than the lower pocket 54b' in both of these dimensions, different exemplary embodiments may vary these relationships. For example, the upper pocket 54a' may be smaller than the lower pocket 54b' in both of these dimensions, and the upper pocket 54a' may be smaller than the lower pocket 54b' in the width dimension but not in the length dimension.

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

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

[0068] The profile / cross-section can be formed by forming a through hole around which one or more channels or grooves are formed, thereby defining recesses or pockets. These features can be formed in any suitable manner, for example, by drilling into the substrate.

[0069] When viewed in cross section, the recesses may be generally U-shaped, semicircular, trapezoidal, and / or the like. Successive drilling operations may be performed to approximate these and / or other shapes, for example, in a more graduated manner.

[0070] In different embodiments, generally circular, elliptical, square, rectangular, and / or other shapes may be used for the through holes and / or recesses when viewed in plan view. For example, generally square, oval, and / or other configurations may be used in different exemplary embodiments when viewed in plan view. It will also be understood that features of different shapes may be used in connection with a single embodiment. For example, when viewed in plan view, an exemplary embodiment may include a generally circular through hole and a groove, channel, or recess that is generally square, rectangular, etc. in its outer extent. Similarly, when viewed in plan view, an exemplary embodiment may include a generally rectangular or square through hole and a groove, channel, or recess that is generally circular, elliptical, etc. in its outer extent.

[0071] The techniques of U.S. Patent No. 9,371,683 (the entire contents of which are incorporated herein by reference) may be used to seal flanged tubes, for example, by tracing increasingly smaller circles or other connected patterns around the tube proximate the sidewall / sealing arms to cause opposing peripheral edges of the sidewall / sealing arms to sag toward one another and form a bridge. If multiple separate sidewall / sealing arms are provided, narrower width incremental scans may be used to similar effect. For example, one or more lasers may be used to scan along first and second upwardly projecting sealing arms to cause them to sag toward one another. The lasers may be focused, for example, along scan lines or scan areas that are closer and closer to one another as sagging continues to occur in the formation of a bridge.

[0072] FIG. 12 is a flow diagram illustrating an exemplary process for fabricating a VIG unit in conjunction with a flanged pump-out tube, according to certain exemplary embodiments. In step S1201, a port profile is formed in a first substrate, such as through one or more drilling operations. That is, in step S1201, through holes and any pockets are formed. Here, cutting, drilling, seaming, and / or other manufacturing processes may be performed. In step S1203, a frit material is applied to the periphery of a second substrate. In step S1205, spacers or pillars are placed on the second substrate. In step S1207, the flanged tube is secured to the first substrate. This may include, for example, applying a frit to the flanged tube before and / or after it is placed against the substrate. A frit may be fired at this point to hermetically seal the flanged tube to the substrate. Alternatively, if the frit and tube can withstand heat treatment (e.g., heat tempering), the flanged tube can be applied to an annealed substrate having a port profile formed therein, and the substrate can be heat treated along with the flanged tube such that the associated hermetic seals are formed together in one process.

[0073] The first and second substrates are registered together in step S1209 such that a cavity is formed therebetween, and a hermetic edge seal is formed (e.g., via laser heating, heating in an oven, using an infrared heater, and / or the like) in step S1211. The cavity is evacuated to a pressure below atmospheric pressure in step S1213.

[0074] The flanged tube is optionally preheated at step S1215 while maintaining the vacuum, for example. This may be accomplished using an oven, using an infrared heater, via a laser, or the like. Core heating is performed at step S1217, and chase heating is performed repeatedly at step S1219 until the tube is sealed (e.g., as shown at step S1221). The core heating process of step S1217 provides the bulk of the melting process, while the chase heating of step S1219 is provided at progressively smaller circumferences, areas, and / or the like, depending on, for example, the configuration of the tube, side walls / sealing arms, through holes, sagging that occurs, etc. Once sealed, the unit may be moved for further processing at step S1223.

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

[0076] In certain exemplary embodiments, a secondary seal may be provided adjacent the sealed flanged tube. This secondary seal may be formed from a softer material, such as a plastic, and may in some cases help to further protect the tube. The secondary seal may simply occupy any space within the outer recess that is not covered by the bridge, for example, such that the outer surface of the VIG unit is flush or substantially flush across its entire width.

[0077] FIG. 13 is a flow diagram illustrating another exemplary process for making a VIG unit in conjunction with an internal encapsulation, in accordance with certain exemplary embodiments.

[0078] FIG. 13 is a flow diagram illustrating another exemplary process for making a VIG unit in conjunction with an internal seal, according to certain exemplary embodiments. FIG. 13 is similar in many respects to FIG. 12. For example, in step S1201, a pump-out tube profile is formed in a first substrate, such as through one or more drilling operations. A flanged tube having a frit is secured to the first substrate in step S1301 using bismuth or other suitable frit. This frit material can withstand heat treatments such as thermal tempering, so that the secured flanged tube and first substrate are both tempered. Thereafter, the process is carried out as described above.

[0079] It will be understood that the steps in the exemplary processes of Figures 12 and 13 may be performed in any suitable order by different parties and / or additional steps may be provided in different exemplary embodiments. For example, a different party may form holes, seat tubes in holes, seal VIGs and / or ports compared to a party making tubes. In certain exemplary embodiments, tube profiles may be formed in a first substrate, the first substrate and / or the second substrate may be tempered, frit may be applied to the periphery of the first substrate and / or the second substrate, spacers may be placed, and then other operations may be performed (e.g., as shown in these figures).

[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 a laser and diameter, the tubes can be sealed by firing through the float glass, and it has been found that approximately 10-30% more energy is required compared to sealing an unobstructed tube. This increase may be provided in time and / or power in different exemplary embodiments.

[0081] It will be understood that the techniques disclosed herein can be used in a wide variety of applications including, for example, VIG window applications, merchandisers, laminated products, hybrid VIG units (e.g., units in which a substrate is spaced apart from a VIG unit via a spacer system), and the like.

[0082] As used herein, the terms "heat treatment" and "heat treating" refer to heating a glass-containing article to a temperature sufficient to achieve thermal tempering and / or thermal strengthening of the article. This definition includes, for example, heating a coated article in an oven or furnace to a temperature of at least about 550°C, more preferably at least about 580°C, more preferably at least about 600°C, more preferably at least about 620°C, and most preferably at least about 650°C for a sufficient period of time to allow tempering and / or thermal strengthening. This may be at least about 2 minutes, or up to about 10 minutes in certain embodiments. These processes may be adapted to involve different times and / or temperatures.

[0083] As used herein, terms such as "on" and "supported by" should not be construed to mean that two elements are directly adjacent to one another unless expressly stated. In other words, a first layer may be "on" or "supported by" a second layer, even if there are one or more layers between the second layer.

[0084] In certain exemplary embodiments, a method of making a VIG unit is provided. A first glass substrate and a second glass substrate are provided. The first substrate includes a hole formed in the first substrate, the hole being formed to have a first portion and a second portion, the first portion being closer to an outer surface of the first substrate than the second portion, the first portion having a first width across the first substrate, the second portion having a second width across the first substrate, the first width being wider than the second width, and 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 disposed within the hole, such that a lower portion of the tube extends into the second portion and an upper portion of the tube is disposed within the first portion. The first and second substrates are sealed together with an edge seal around the periphery of the first and / or second substrates, a cavity defined by the first and second substrates, and a number of spacers disposed within the cavity between the first and second substrates and helping to maintain the first and second substrates in a substantially parallel spaced apart relationship with respect to one another. The cavity is evacuated to a pressure below atmospheric pressure. The pump-out tube is heated such that at least a portion of an upper portion of the tube collapses inwardly onto itself, covering the second width and sealing the VIG unit to form a sealed tube, the sealed tube being flush with or partially recessed relative to the outermost surface of the first substrate.

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

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

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

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

[0089] In addition to the features of any of the previous three paragraphs, in certain exemplary embodiments, frit material may or may not be provided on the underside of the skirt.

[0090] In addition to the features of any of the previous four paragraphs, in certain exemplary embodiments, a frit material may be provided to the pump-out tube before the tube is disposed within the bore.

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

[0092] In addition to any of the features of the previous eight paragraphs, in certain exemplary embodiments, laser heating may be performed 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 previous nine paragraphs, in certain exemplary embodiments, the laser heating may include tracing a collapsed portion of the tube, such that the tube collapses inwardly upon itself, e.g., in forming a sealed tube.

[0094] In certain exemplary embodiments, a method of making a VIG unit subassembly is provided, the method including providing a first glass substrate including a hole formed therein, the hole being formed to have a first portion and a second portion, the first portion being closer to an outer surface of the first substrate than the second portion, the first portion having a first width across the first substrate and the second portion having a second width across the first substrate, the first width being greater than the second width, and the first and second portions together forming a through hole through the first substrate. The first substrate is transferred to another batch, a flanged pump-out tube including a skirt intermediate an upper portion and a lower portion is placed in the hole such that a lower portion of the tube extends into the second portion and an upper portion of the tube is placed in the first portion, the first glass substrate and the second glass substrate are sealed to one another in association with an edge seal provided around a periphery of the first substrate and / or the second substrate, a cavity is defined by the first substrate and the second substrate, a plurality of spacers are provided within the cavity to support the first substrate and the second substrate. A cavity disposed therebetween and assisting in maintaining the first and second substrates in a substantially parallel spaced apart relationship from one another is evacuated to a pressure less than atmospheric pressure and the pump-out tube is laser heated, thereby causing at least a portion of an upper portion of the tube to collapse inwardly onto itself, covering the second width and hermetically sealing the VIG unit to form a sealed tube, the sealed tube being either flush with or partially concave relative to the outermost surface of the first substrate.

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

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

[0097] In addition to the features of any of the previous three paragraphs, in certain exemplary embodiments, the frit material may seal the skirt to the first substrate.

[0098] In addition to the features of any of the previous four paragraphs, in certain exemplary embodiments, the frit material may seal the peripheral edge of the skirt to the first substrate.

[0099] Certain exemplary embodiments relate to VIG units made by the method of any one of the preceding 15 paragraphs.

[0100] In a particular exemplary embodiment, a VIG unit is provided. A first glass substrate and a second glass substrate are maintained in a substantially parallel spaced relationship with each other via a hermetic edge seal and a number of spacers disposed in a cavity defined between the first glass substrate and the second glass substrate. The cavity is evacuated to a pressure lower than atmospheric pressure using a pump-out port formed in the first substrate hermetically sealed with a laser-sealed flanged tube. The laser-sealed tube includes a seal portion made therefrom adjacent to the cavity, and the laser-sealed tube is disposed inside the VIG unit without protruding therefrom.

[0101] In addition to the features of the previous paragraph, in certain exemplary embodiments, the tube may be connected to the first substrate of the VIG unit via a frit material.

[0102] In addition to the features of either of the previous two paragraphs, in certain exemplary embodiments, the frit material connecting the tube to the first substrate may be provided around the skirt of the tube.

[0103] In addition to the features of any of the previous three paragraphs, in certain exemplary 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 toward the cavity.

[0104] While the present invention has been described in connection with what are presently considered to be practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but rather is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. 1. A method of making a vacuum insulating glass (VIG) unit, comprising: a first glass substrate and a second glass substrate, the first substrate including a hole therein, the hole having a first portion and a second portion, the first portion being closer to an outer surface of the first substrate than the second portion, the first portion having a first width across the first substrate and the second portion having a second width across the first substrate, the first width being greater than the second width, and the first and second portions together forming a through hole through the first substrate; placing a flanged pump-out tube into the hole, the flanged pump-out tube including a skirt disposed on an outer surface of the first glass substrate intermediate upper and lower portions of the flanged pump-out tube, the placing causing the lower portion of the tube to extend at least partially into the second portion of the hole and the upper portion of the tube to be disposed at least partially into the first portion of the hole; sealing an area adjacent to an outer periphery of the first and second glass substrates with an edge seal (4) provided around a peripheral edge of the first and / or second glass substrates, wherein a cavity is defined between at least the first and second glass substrates, and a plurality of spacers are provided between the first and second glass substrates within the cavity to help maintain the first and second glass substrates in a substantially parallel spaced apart relationship with respect to one another; evacuating the cavity to a pressure less than atmospheric; and laser heating the pump-out tube, thereby causing at least a portion of the upper portion of the tube to collapse inwardly onto itself, covering the second width and hermetically sealing the VIG unit, forming a sealed tube, the sealed tube being flush with or partially recessed relative to an outermost surface of the first glass substrate, wherein the skirt is more transparent to the wavelength of the laser than the upper portion and avoids absorbing laser energy.

2. The method of claim 1 , wherein the first and second portions of the hole are formed by drilling.

3. 3. The method of claim 1 or 2, further comprising sealing the pump-out tube to the first glass substrate using a frit material provided on the pump-out tube and / or the first glass substrate.

4. The method of claim 3 , wherein the frit material seals the skirt to the first glass substrate.

5. The method of claim 3 or 4, wherein the frit material seals a peripheral edge of the skirt to the first glass substrate.

6. The method of any one of claims 3 to 5, wherein no frit material is provided on the underside of the skirt.

7. The method of any one of claims 3 to 6, wherein a frit material is provided on the pump-out tube before the tube is placed in the bore.

8. 8. The method of claim 1, wherein the laser heating is performed to preferentially heat the pump-out tube relative to the first glass substrate and / or the skirt.

9. 9. The method of claim 1, wherein the laser heating includes tracing a collapsed portion of the tube such that the tube collapses inwardly upon itself in forming the sealed tube.

10. 1. A method of making a vacuum insulating glass (VIG) unit subassembly, comprising: the vacuum insulated glass (VIG) unit subassembly includes a first glass substrate, the first glass substrate including a hole formed therein, the hole being formed to have a first portion and a second portion, the first portion being closer to an outer surface of the first glass substrate than the second portion, the first portion having a first width across the first glass substrate and the second portion having a second width across the first glass substrate, the first width being greater than the second width, the first portion and the second portion together forming a through hole through the first glass substrate; placing a flanged pump-out tube into the hole, the skirt including a skirt disposed on an outer surface of the first glass substrate intermediate an upper portion and a lower portion, such that the lower portion of the tube extends into the second portion and the upper portion of the tube is disposed within the first portion; sealing the first and second glass substrates together in association with an edge seal disposed around a periphery of the first and / or second glass substrates, wherein a cavity is defined by the first and second glass substrates, and a plurality of spacers are disposed within the cavity between the first and second glass substrates to assist in maintaining the first and second glass substrates in a substantially parallel spaced apart relationship to one another; evacuating the cavity to a pressure less than atmospheric pressure; and and laser heating the pump-out tube, thereby causing at least a portion of the upper portion of the tube to collapse inwardly onto itself, covering the second width, hermetically sealing the VIG unit, and forming a sealed tube, wherein the sealed tube is flush with or partially concave relative to an outermost surface of the first glass substrate, wherein the skirt is more transparent to the wavelength of the laser than the upper portion and avoids absorbing laser energy.

11. The method of claim 10 , wherein the first and second portions of the hole are formed by drilling.

12. 12. The method of claim 10 or 11, wherein the pump-out tube is sealed to the first glass substrate using a frit material provided on the pump-out tube and / or the first glass substrate.

13. The method of claim 12 , wherein the frit material seals the skirt to the first glass substrate.

14. 14. The method of claim 12 or 13, wherein the frit material seals a peripheral edge of the skirt to the first glass substrate.

15. 1. A vacuum insulating glass (VIG) unit comprising: a first glass substrate and a second glass substrate maintained substantially parallel and spaced apart from one another via at least one hermetic edge seal and a plurality of spacers disposed within a cavity defined between the first glass substrate and the second glass substrate; the cavity being evacuated to a pressure below atmospheric pressure using a pump-out port formed in a first glass substrate hermetically sealed with a flanged tube, the tube including a sealing portion formed adjacent the cavity, the tube being disposed within the VIG unit without protruding from the VIG unit; the tube includes an upper portion that projects through the through hole in the first glass substrate toward a side opposite the cavity, and at least a portion of the upper portion is collapsed inwardly onto itself; A VIG unit, wherein the tube includes a lower portion extending toward the cavity and a skirt disposed on an outer surface of the first glass substrate intermediate the upper portion and the lower portion, the skirt being more transparent to the wavelength of the laser than the upper portion and avoiding absorbing the energy of the laser.

16. 16. The VIG unit of claim 15, wherein the tube is connected to the first glass substrate of the VIG unit via a frit material.

17. 17. The VIG unit of claim 16, wherein the frit material connecting the tube to the first glass substrate is provided around a skirt of the tube.

18. 18. A VIG unit according to any of claims 15 to 17, wherein the skirt is intermediate the sealing portion and the lower portion of the tube.

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