Laser bonding of glass to thin metal foil

Abstract

A method for laser bonding glass to a metal foil includes contacting a first glass substrate with a first metal foil to create a first contact location; guiding a laser beam at the first contact location to bond the first glass substrate to the first metal foil; contacting a second glass substrate with a second metal foil to create a second contact location; and guiding a laser beam at the second contact location to bond the second glass substrate to the second metal foil, wherein the first and second metal foils each have a thickness from 5 µm to 100 µm, and wherein the laser beam includes a pulsed laser, the pulsed laser including a pulse energy from 2.8 µJ to 1000 µJ; and a wavelength such that the first and second glass substrates are substantially transparent to the wavelength.

Description

Technical Field

[0001] This case asserts priority rights under the Patent Act to U.S. Provisional Application No. 63 / 238515, filed August 30, 2021, and U.S. Provisional Application No. 63 / 274984, filed November 3, 2021, the contents of which are incorporated herein by reference in their entirety.

[0002] This specification generally pertains to glass bonded to metal foil, and more specifically to laser bonding of glass to thin metal foil. Prior Technology

[0003] Hermetically bonded glass and metal foil packaging is increasingly used in electronic devices and other applications that benefit from a hermetically sealed environment for continuous operation. However, conventional laser bonding processes can cause undesirable thermally related defects in the areas adjacent to the bond.

[0004] Therefore, there is a need for alternative methods to produce laser-bonded glass and metal foil packages while minimizing thermal defects in the areas adjacent to the bonding. Summary of the Invention

[0005] According to first state sample A1, a method for laser bonding glass to a metal foil may include: positioning a first surface of a first glass substrate adjacent to a first surface of a second glass substrate; contacting a second surface of the first glass substrate with a first surface of a first metal foil to create a first contact position between at least a portion of the second surface of the first glass substrate and the first surface of the first metal foil; performing a first welding step by guiding a laser beam over at least a portion of the first contact position to bond the first glass substrate to the first metal foil and form the first bonding position; contacting a second surface of the second glass substrate with a first surface of the second metal foil to create a second contact position between at least a portion of the second surface of the second glass substrate and the first surface of the second metal foil; and performing a second welding step by guiding a laser beam over at least a portion of the second contact position to bond the second glass substrate to the second metal foil and form the second bonding position, wherein the first metal foil and the second metal foil each have a thickness greater than or equal to 5 µm and less than or equal to 100 µm, and wherein the laser beam includes a pulsed laser, the pulsed laser including: a pulse energy greater than or equal to 2.8 µJ and less than or equal to 1000 J. µJ; and wavelength, such that the first glass substrate and the second glass substrate are substantially transparent to the wavelength of the laser beam, and the first metal foil and the second metal foil are substantially opaque to the wavelength of the laser beam.

[0006] The second state sample A2 includes the method according to the first state sample A1, wherein at least one of the first adhesive position and the second adhesive position has a maximum adhesive depth of less than or equal to 20 µm.

[0007] The third state sample A3 includes a method according to the first state sample A1 or the second state sample A2, wherein the first metal foil and the second metal foil are sealed to produce a hermetically sealed package.

[0008] The fourth state sample A4 includes a method according to any one of the first to third state samples A1-A3, wherein the pulsed laser has a wavelength greater than or equal to 300 nm and less than or equal to 1100 nm.

[0009] The fifth state sample A5 includes a method according to any one of the first to fourth states samples A1-A4, wherein the pulsed laser is a nanosecond pulsed laser, a picosecond pulsed laser, or a femtosecond pulsed laser.

[0010] The sixth state sample A6 includes a method according to any one of the first to fifth state samples A1-A5, wherein the pulsed laser has a repetition rate greater than or equal to 5 kHz and less than or equal to 1 MHz.

[0011] The seventh state sample A7 includes the method according to any one of the first to sixth state samples A1-A6, wherein the pulsed laser has a spot size greater than or equal to 5 µm and less than or equal to 50 µm.

[0012] The eighth state sample A8 includes a method according to any one of the first to seventh states A1-A7, wherein the laser beam is guided at an oblique incident angle relative to the first glass substrate and the second glass substrate.

[0013] The ninth state sample A9 includes the method according to the eighth state sample A8, wherein the angle of incidence is less than or equal to 30°.

[0014] The tenth state sample A10 includes a method according to the eighth state sample A8 or the ninth state sample A9, wherein a lens is optically positioned upstream of both the first glass substrate and the second glass substrate, such that the laser beam travels through the lens before traveling through the first glass substrate and the second glass substrate.

[0015] Eleventh state sample A11 includes a method according to any one of the first to tenth states A1-A10, wherein during the first welding step, the first glass substrate is optically positioned downstream of the second glass substrate such that the laser beam travels through the second glass substrate and then through the first glass substrate before reaching the first contact position.

[0016] The twelfth state sample A12 includes a method according to any one of the first to eleventh states A1-A11, wherein during the second welding step, the second glass substrate is optically positioned downstream of the first glass substrate such that the laser beam travels through the first glass substrate and then through the second glass substrate before reaching the second contact position.

[0017] The thirteenth state sample A13 includes a method according to any one of the first to seventh states samples A1-A7, wherein during the first welding step, the first metal foil is optically positioned upstream of the first glass substrate such that the laser beam contacts the first metal foil to bond the first metal foil to the first glass substrate.

[0018] The fourteenth state sample A14 includes the method according to the thirteenth state sample A13, wherein a laser beam removes a portion of the first metal foil before the first metal foil is bonded to the first glass substrate.

[0019] The fifteenth state sample A15 includes a method according to any one of the first to fourteenth states samples A1-A14, wherein the first glass substrate and the second glass substrate have refractive indices greater than or equal to 1.5 and less than or equal to 2.4.

[0020] The sixteenth state sample A16 includes a method according to any one of the first to fifteenth states samples A1-A15, wherein the first glass substrate and the second glass substrate comprise glass, glass ceramic, or ceramic, and the glass, glass ceramic, or ceramic comprises borate glass, silica borate glass, phosphate glass, silicate glass, sodium calcium silicate glass, aluminosilicate glass, alkali metal aluminosilicate glass, borosilicate glass, alkali metal borosilicate glass, aluminosilicate glass, alkali metal aluminosilicate glass, alkali metal aluminosilicate glass, or sapphire.

[0021] The seventeenth state sample A17 includes a method according to any one of the first to sixteenth states samples A1-A16, wherein at least one of the first metal foil and the second metal foil comprises aluminum, aluminum alloy, stainless steel, nickel, nickel alloy, silver, silver alloy, titanium, titanium alloy, tungsten, tungsten alloy, gold, gold alloy, copper, copper alloy, bronze, iron, or a combination of the foregoing.

[0022] The eighteenth state sample A18 includes a method according to any one of the first to seventeenth states samples A1-A17, wherein at least one of the first metal foil and the second metal foil has a melting point of less than or equal to 1600 °C.

[0023] Additional features and advantages of the laser bonding method described herein will be apparent to those skilled in the art, as will be set forth in the following embodiments and in part from the description or by practicing the embodiments described herein, including the following embodiments, the claims, and as understood with reference to the accompanying drawings.

[0024] The foregoing summary and the following description of various embodiments are intended to provide an overview or architecture for understanding the nature and characteristics of the claimed object. The accompanying drawings are included to provide a further understanding of the various embodiments and are incorporated in and constitute a part of this specification. The drawings illustrate the various embodiments described herein and, together with the specification, serve to explain the principles and operation of the claimed object. Simple Explanation of the Diagram

[0025] Figure 1 is a flowchart of a method for laser bonding glass and metal foil according to one or more embodiments shown and described herein;

[0026] Figure 2 schematically depicts a step of a laser bonding method according to one or more embodiments shown and described herein;

[0027] Figure 3 schematically depicts another step of the laser bonding method according to one or more embodiments shown and described herein;

[0028] Figure 4 is a scanning electron microscope image of a metal foil bonded to glass according to one or more embodiments shown and described herein;

[0029] Figure 5 illustrates another step of the laser bonding method according to one or more embodiments shown and described herein;

[0030] Figure 6 illustrates another step of the laser bonding method according to one or more embodiments shown and described herein;

[0031] Figure 7 schematically depicts an alternative step in a laser bonding method according to one or more embodiments shown and described herein;

[0032] Figure 8 illustrates another step of the laser bonding method according to one or more embodiments shown and described herein;

[0033] Figure 9 illustrates another step of the laser bonding method according to one or more embodiments shown and described herein;

[0034] Figure 10 schematically depicts a step of an alternative laser bonding method according to one or more embodiments shown and described herein; and

[0035] Figure 11 illustrates another step of an alternative laser bonding method according to one or more embodiments shown and described herein. Implementation

[0036] Various embodiments of a method for laser bonding glass and metal foil while minimizing associated thermal defects in the region adjacent to this bonding will now be described in detail. According to an embodiment, the method for laser bonding glass and metal foil includes positioning a first surface of a first glass substrate adjacent to a first surface of a second glass substrate; contacting a second surface of the first glass substrate with a first surface of a first metal foil to create a first contact position between at least a portion of the second surface of the first glass substrate and the first surface of the first metal foil; performing a first welding step by guiding a laser beam over at least a portion of the first contact position to bond the first glass substrate to the first metal foil and form the first bonding position; contacting a second surface of the second glass substrate with a first surface of the second metal foil to create a second contact position between at least a portion of the second surface of the second glass substrate and the first surface of the second metal foil; and performing a second welding step by guiding a laser beam over at least a portion of the second contact position to bond the second glass substrate to the second metal foil and form the second bonding position. The first metal foil and the second metal foil each have a thickness greater than or equal to 5 µm and less than or equal to 100 µm. The laser beam comprises a pulsed laser having a pulse energy greater than or equal to 2.8 µJ and less than or equal to 1000 µJ; and a wavelength such that the first and second glass substrates are substantially transparent to the wavelength of the laser beam, and the first and second metal foils are substantially opaque to the wavelength of the laser beam. Various embodiments of laser-bonded glass and metal foils and the packaging formed therefrom will be specifically described with reference to the accompanying drawings.

[0037] A range may be expressed herein as from “about” a specific value and / or to “about” another specific value. When such a range is expressed, another embodiment includes from this specific value and / or to this other specific value. Similarly, when a value is expressed as an approximate value by using the prefix “about”, it will be understood that this specific value forms another embodiment. It will be further understood that the endpoints of each of the ranges are important both with respect to and independently of the other endpoints.

[0038] The directional terms used here—such as up, down, right, left, front, back, top, bottom—are derived only with reference to the depicted diagram and are not intended to imply absolute orientation.

[0039] Unless otherwise expressly stated, it is not intended that any method described herein be construed as requiring its steps to be performed in a particular order, or requiring any device with a particular orientation. Therefore, if a method claim does not explicitly describe the order in which its steps are followed, or any device claim does not explicitly describe the order or orientation of individual components, or if the steps are not otherwise expressly stated in the claims or specification, or if a particular order or orientation of the components of a device is not stated, it is not intended to infer any order or orientation in any manner. This applies to any possible non-explanatory basis for interpretation, including: logical matters concerning the arrangement of steps, operational flow, order of components, or orientation of components; literal meaning derived from grammatical structures or punctuation; and the number or type of embodiments described in this specification.

[0040] When used here, unless the context clearly indicates otherwise, the singular forms "a," "an," and "the" include plural indicators. Thus, unless the context clearly indicates otherwise, for example, reference to the "a" component includes a state having two or more of this component.

[0041] The terms "hermetically bonded" or "hermetically sealed" as used herein refer to packaging that is hermetically sealed according to MIL-STD-750E, test method 1071.9.

[0042] The “maximum adhesion depth” described herein and determined using scanning electron microscopy refers to the depth in the thickness direction of the glass substrate / metal foil interface, which can be partially visible within the glass substrate and partially visible within the metal foil, as shown in Figure 4.

[0043] Hermetically bonded glass and metal foil packaging can be used in devices that benefit from hermetically sealed packaging, such as televisions, sensors, optical devices, organic light-emitting diode (OLED) displays, 3D inkjet printers, solid-state light sources, batteries, and optoelectronic structures. Conventional laser bonding processes involve using high-energy lasers to bond thick metal foils (e.g., foils with a thickness greater than 50 µm) to glass. However, the heating caused by using high-energy lasers can result in associated thermal defects (e.g., cracking) in the area adjacent to the bond.

[0044] This paper discloses a method for laser bonding of glass and metal foil that mitigates the aforementioned problems by minimizing associated thermal defects in the region adjacent to the bond. Specifically, the laser bonding method for glass and metal foil disclosed herein utilizes a low-energy laser to bond thin metal foil (e.g., foil having a thickness greater than or equal to 5 µm and less than or equal to 50 µm) to glass to produce a hermetically bonded package with a reduced maximum bond depth (e.g., less than or equal to 20 µm or less than or equal to 10 µm).

[0045] Referring now to Figures 1 and 2, the laser bonding method 100 for glass and metal foil begins at block 102, where a first glass substrate 200 and a second glass substrate 202 are positioned. The first glass substrate 200 and the second glass substrate 202 each have a first surface 200a, 202a and a second surface 200b, 202b opposite to the first surface 200a, 202a.

[0046] A first surface 200a of the first glass substrate 200 is placed adjacent to a first surface 202a of the second glass substrate 202. In an embodiment, as illustrated, the first glass substrate 200 and the second glass substrate 202 may not be in direct contact with each other, allowing one or more other glass substrates or components (e.g., electronic components) to be placed therein to protect the additional substrates or components from different environmental conditions, such as pressure changes, moisture, bodily fluids, or the like. In an embodiment, the first glass substrate 200 and the second glass substrate 202 may be in direct contact (not shown). In an embodiment, the first glass substrate 200 and the second glass substrate 202 may be a single substrate having a sealed cavity (e.g., formed from the edge) as described herein.

[0047] In one embodiment, the first and second glass substrates 200 and 202 may have refractive indices greater than or equal to 1.5 and less than or equal to 2.4. In another embodiment, the first and second glass substrates 200 and 202 may have refractive indices greater than or equal to 1.5, greater than or equal to 1.6, greater than or equal to 1.7, greater than or equal to 1.8, or even greater than or equal to 1.9. In yet another embodiment, the first and second glass substrates 200 and 202 may have refractive indices less than or equal to 2.4, less than or equal to 2.3, or even less than or equal to 2.2. In embodiments, the first and second glass substrates 200 and 202 may include refractive indices greater than or equal to 1.5 and less than or equal to 2.4, greater than or equal to 1.5 and less than or equal to 2.3, greater than or equal to 1.5 and less than or equal to 2.2, greater than or equal to 1.6 and less than or equal to 2.4, greater than or equal to 1.6 and less than or equal to 2.3, greater than or equal to 1.6 and less than or equal to 2.2, greater than or equal to 1.7 and less than or equal to 2.4, greater than or equal to 1.7 and less than or equal to 2.3, greater than or equal to 1.7 and less than or equal to 2.2, greater than or equal to 1.8 and less than or equal to 2.4, greater than or equal to 1.8 and less than or equal to 2.3, greater than or equal to 1.8 and less than or equal to 2.2, greater than or equal to 1.9 and less than or equal to 2.4, greater than or equal to 1.9 and less than or equal to 2.3, or even greater than or equal to 1.9 and less than or equal to 2.2, or any and all subranges formed by any of these endpoints.

[0048] In embodiments, the first and second glass substrates 200, 202 may comprise glass or glass-ceramic. In some embodiments, the first and / or second glass substrates 200, 202 may be completely or substantially completely ceramicized, such that they comprise ceramic material. As a non-limiting example, the first and second glass substrates 200, 202 may comprise borate glass, borosilicate glass, phosphate glass, silicate glass, soda-lime silicate glass, aluminosilicate glass, alkali metal aluminosilicate glass, borosilicate glass, alkali metal borosilicate glass, aluminosilicate glass, alkali metal aluminosilicate glass, alkali metal aluminosilicate glass, or sapphire. In embodiments where a relatively high refractive index glass is desired (e.g., a refractive index greater than or equal to 1.5 and less than or equal to 2.4), the first and second glass substrates 200, 202 may comprise borate glass or borosilicate glass, such as the glass described in U.S. Provisional Patent Application No. 63 / 228,704, the entire contents of which are incorporated herein by reference. In embodiments, the first and second glass substrates 200, 202 may be chemically strengthened, chemically tempered, and / or thermally tempered. Non-limiting examples of suitable commercially available glass substrates include EAGLE XG®, Lotus™, Willow®, and Gorilla® glasses from Corning Incorporated, including chemically strengthened, chemically tempered, and / or thermally tempered versions of these glasses. In embodiments, glass and glass-ceramics that have been chemically strengthened by ion exchange may be suitable as substrates. In other embodiments, the first and / or second glass substrates 200, 202 may be strengthened glass-to-glass laminates.

[0049] In an embodiment, the first and second glass substrates 200 and 202 may include a coating (not shown). In an embodiment, the coating may include a refractive index similar to that of the first and second glass substrates 200 and 202. In an embodiment, the coating may include a polymer coating, an anti-reflective (AR) coating, an oleophobic coating, an anti-glare coating, or a scratch-resistant coating.

[0050] In an embodiment, the first and second glass substrates 200, 202 may be formed of a material that is substantially transparent to a selected wavelength of the laser beam. The term "substantially transparent" means that the wavelength of the laser beam passes through this material without being substantially absorbed or scattered. For example, in an embodiment, the material that is substantially transparent to the laser beam may be a material exhibiting a transmittance of greater than or equal to 90% at that wavelength. In an embodiment, the first and second glass substrates 200, 202 may be substantially transparent to light wavelengths greater than or equal to 300 nm and less than or equal to 1100 nm, or even greater than or equal to 330 nm and less than or equal to 750 nm.

[0051] In an embodiment, the first and second glass substrates 200, 202 may undergo surface pretreatment prior to bonding the glass substrates to the metal foil. For example, in an embodiment, the first and second glass substrates 200, 202 may be polished until their surfaces exhibit a relatively low surface roughness value, which can improve adhesion. In an embodiment, the first and / or second surfaces 200a, 200b, 202a, 202b of the first and second glass substrates 200, 202 may be polished until the first and / or second surfaces 200a, 200b, 202a, 202b exhibit an average surface roughness (Ra) less than or equal to 1 µm, less than or equal to 0.5 µm, or even less than or equal to 0.25 µm. This smooth surface allows the first and second glass substrates to be placed in close contact with the metal foil (e.g., within a few µm of each other). Furthermore, the first and second glass substrates 200 and 202 can be cleaned with water and / or solvents to remove any debris and / or materials (oil, grease, etc.) present on their surfaces that would reduce the substrate's transparency for the desired laser wavelength. Removal of any debris allows the first and second glass substrates to be placed in close contact with the metal foil, thereby better promoting laser adhesion between the metal foil and the glass.

[0052] Referring back to Figure 1 and Figure 3, in block 104, the second surface 200b of the first glass substrate 200 contacts the first surface 204a of the first metal foil 204 to create a first contact position 206 between at least a portion of the second surface 200b of the first glass substrate 200 and the first surface 204a of the first metal foil 204.

[0053] In one embodiment, the first metal foil 204 may have a thickness less than or equal to 100 µm. In another embodiment, the first metal foil 204 may have a thickness greater than or equal to 5 µm and less than or equal to 100 µm. In yet another embodiment, the first metal foil 204 may have a thickness greater than or equal to 5 µm, greater than or equal to 10 µm, or even greater than or equal to 20 µm. In yet another embodiment, the first metal foil 204 may have a thickness less than or equal to 100 µm, less than or equal to 90 µm, less than or equal to 80 µm, less than or equal to 70 µm, less than or equal to 60 µm, less than or equal to 50 µm, less than or equal to 40 µm, or even less than or equal to 30 µm. In an embodiment, the first metal foil 204 may have a thickness greater than or equal to 5 µm and less than or equal to 100 µm, greater than or equal to 5 µm and less than or equal to 50 µm, greater than or equal to 5 µm and less than or equal to 40 µm, greater than or equal to 5 µm and less than or equal to 30 µm, greater than or equal to 10 µm and less than or equal to 100 µm, greater than or equal to 10 µm and less than or equal to 50 µm, greater than or equal to 10 µm and less than or equal to 40 µm, greater than or equal to 10 µm and less than or equal to 30 µm, greater than or equal to 20 µm and less than or equal to 100 µm, greater than or equal to 20 µm and less than or equal to 50 µm, greater than or equal to 20 µm and less than or equal to 40 µm, or even greater than or equal to 20 µm and less than or equal to 30 µm, or any and all subranges formed by any of the endpoints of these endpoints.

[0054] In an embodiment, the first metal foil 204 may comprise aluminum, aluminum alloy, stainless steel, nickel, nickel alloy, silver, silver alloy, titanium, titanium alloy, tungsten, tungsten alloy, gold, gold alloy, copper, copper alloy, bronze, iron, or a combination of the foregoing. In an embodiment, the first metal foil 204 may comprise a combination of a metal and another non-metallic material.

[0055] In an embodiment, the first metal foil 204 may be formed of a material having a melting point that allows for successful adhesion to a glass substrate. In an embodiment, the first metal foil 204 may contain materials with melting points less than or equal to 1600 °C, less than or equal to 1500 °C, and less than or equal to 1400 °C.

[0056] In an embodiment, the first metal foil 204 may be formed of a material that is chemically compatible with the glass substrate (i.e., easy to bond). For example, a glass substrate comprising aluminum can be more easily bonded to an aluminum metal foil.

[0057] In an embodiment, the first metal foil 204 may be formed of a material that is substantially opaque to a selected wavelength of the laser beam. The term "substantially opaque" means that the wavelength of the laser beam is substantially absorbed when it comes into contact with the material. For example, in an embodiment, a material that is substantially opaque to the wavelength of the laser beam may be a material exhibiting an absorption rate of 35% or greater at that wavelength.

[0058] In an embodiment, the first metal foil 204 may have an average roughness (Ra) similar to that of the first glass substrate 200, so as to similarly allow the first glass substrate 200 to be placed in close contact with the metal foil 204.

[0059] Referring back to Figure 1 and Figure 3, in block 106, a first welding step is performed by guiding the laser beam 208 onto at least a portion of the first contact position 206 to bond the first glass substrate 200 and the first metal foil 204.

[0060] In one embodiment, the laser beam 208 comprises a pulsed laser. In another embodiment, the pulsed laser may be a nanosecond pulsed laser, a picosecond pulsed laser, or a femtosecond pulsed laser.

[0061] The laser bonding method described herein utilizes a low-energy laser to bond metal foil to glass, thereby minimizing associated thermal defects in the adjacent area. In embodiments, the pulsed laser may contain pulse energies greater than or equal to 2.8 µJ and less than or equal to 1000 µJ. In embodiments, the pulsed laser may contain pulse energies greater than or equal to 2.8 µJ, greater than or equal to 10 µJ, greater than or equal to 25 µJ, or even greater than or equal to 50 µJ. In embodiments, the pulsed laser may contain pulse energies less than or equal to 1000 µJ, less than or equal to 750 µJ, less than or equal to 500 µJ, or even less than or equal to 250 µJ. In embodiments, the pulsed laser may include pulse energies greater than or equal to 2.8 µJ and less than or equal to 1000 µJ, greater than or equal to 2.8 µJ and less than or equal to 750 µJ, greater than or equal to 2.8 µJ and less than or equal to 500 µJ, greater than or equal to 2.8 µJ and less than or equal to 250 µJ, greater than or equal to 10 µJ and less than or equal to 1000 µJ, greater than or equal to 10 µJ and less than or equal to 750 µJ, greater than or equal to 10 µJ and less than or equal to 500 µJ, greater than or equal to 10 µJ and less than or equal to 250 µJ, greater than or equal to 25 µJ and less than or equal to 1000 µJ, greater than or equal to 25 µJ and less than or equal to 750 µJ, greater than or equal to 25 µJ and less than or equal to 500 µJ, greater than or equal to 25 µJ and less than or equal to 250 µJ, greater than or equal to 50 µJ and less than or equal to 1000 µJ, greater than or equal to 50 µJ. µJ and less than or equal to 750 µJ, greater than or equal to 50 µJ and less than or equal to 500 µJ, or even greater than or equal to 50 µJ and less than or equal to 250 µJ, or any and all subranges formed by any of these endpoints.

[0062] In embodiments, the pulsed laser may have a wavelength such that the first glass and / or the second glass substrates 200, 202 are substantially transparent to this wavelength of the laser beam, while the first metal foil 204 is substantially opaque to this wavelength of the laser beam. For example, in embodiments, the pulsed laser may have a wavelength greater than or equal to 300 nm and less than or equal to 1100 nm. In embodiments, the pulsed laser may have a wavelength greater than or equal to 300 nm, greater than or equal to 325 nm, or even greater than or equal to 350 nm. In embodiments, the pulsed laser may have a wavelength less than or equal to 1100 nm, less than or equal to 900 nm, or even less than or equal to 700 nm. In embodiments, the pulsed laser may have wavelengths greater than or equal to 300 nm and less than or equal to 1100 nm, greater than or equal to 300 nm and less than or equal to 900 nm, greater than or equal to 300 nm and less than or equal to 700 nm, greater than or equal to 325 nm and less than or equal to 1100 nm, greater than or equal to 325 nm and less than or equal to 900 nm, greater than or equal to 325 nm and less than or equal to 700 nm, greater than or equal to 350 nm and less than or equal to 1100 nm, greater than or equal to 350 nm and less than or equal to 900 nm, or even greater than or equal to 350 nm and less than or equal to 700 nm, or any and all subranges formed by any of these endpoints.

[0063] In embodiments, the pulsed laser may comprise a high-repetition-pulse UV laser, operating at about 355 nm, 532 nm, 1064 nm, or any other applicable wavelength, depending on the glass penetration.

[0064] In one embodiment, the pulsed laser may have a repetition rate greater than or equal to 5 kHz and less than or equal to 1 MHz. In another embodiment, the pulsed laser may have a repetition rate greater than or equal to 5 kHz, greater than or equal to 50 kHz, greater than or equal to 100 kHz, or even greater than or equal to 250 kHz. In yet another embodiment, the pulsed laser may have a repetition rate less than or equal to 1 MHz, less than or equal to 750 kHz, or even less than or equal to 500 kHz. In embodiments, the pulsed laser may have repetition rates greater than or equal to 5 kHz and less than or equal to 1 MHz, greater than or equal to 5 kHz and less than or equal to 750 kHz, greater than or equal to 5 kHz and less than or equal to 500 kHz, greater than or equal to 50 kHz and less than or equal to 1 MHz, greater than or equal to 50 kHz and less than or equal to 750 kHz, greater than or equal to 50 kHz and less than or equal to 500 kHz, greater than or equal to 100 kHz and less than or equal to 1 MHz, greater than or equal to 100 kHz and less than or equal to 750 kHz, greater than or equal to 100 kHz and less than or equal to 500 kHz, greater than or equal to 250 kHz and less than or equal to 1 MHz, greater than or equal to 250 kHz and less than or equal to 750 kHz, or even greater than or equal to 250 kHz and less than or equal to 500 kHz, or any and all subranges formed by any of these endpoints.

[0065] In an embodiment, the pulsed laser may have a spot size greater than or equal to 5 µm and less than or equal to 50 µm. In an embodiment, the pulsed laser may have a spot size greater than or equal to 5 µm or even greater than or equal to 10 µm. In an embodiment, the pulsed laser may have a spot size less than or equal to 50 µm, less than or equal to 35 µm, or even less than or equal to 20 µm. In an embodiment, the pulsed laser may have a spot size greater than or equal to 5 µm and less than or equal to 50 µm, greater than or equal to 5 µm and less than or equal to 35 µm, greater than or equal to 5 µm and less than or equal to 35 µm, or even greater than or equal to 10 µm and less than or equal to 20 µm, or any and all sub-ranges formed by any of these endpoints.

[0066] In an embodiment, as shown in Figure 3, during the first welding step, the first glass substrate 200 is optically positioned downstream of the second glass substrate 202 such that the laser beam 208 travels through the second glass substrate 202, and then through the first glass substrate 200, before being incident on the first contact position 206. The laser beam 208 may traverse along the first contact position 206 to facilitate line bonding between the glass and the foil. For example, the laser beam may traverse along the first contact position 206 (e.g., enter and / or exit this page and / or traverse the plane of the page in Figure 3) to facilitate line bonding between the glass and the foil.

[0067] As described herein, the laser bonding method for glass and metal foil disclosed herein utilizes a lower energy laser to minimize associated thermal defects in the region adjacent to the bonding, by reducing the maximum bonding depth (i.e., the reduced maximum bonding depth 211 is less than or equal to 20 µm), as shown in Figure 4. Referring back to Figure 3, in an embodiment, the first bonding location 210 may have a maximum bonding depth less than or equal to 20 µm, less than or equal to 10 µm, less than or equal to 8 µm, or even less than or equal to 6 µm. In some embodiments, the maximum bonding depth, or the portion thereof manifested within the glass substrate (e.g., excluding any portion of the bonding manifested within the metal foil), may be less than or equal to 20 µm, less than or equal to 10 µm, less than or equal to 8 µm, or even less than or equal to 6 µm.

[0068] Referring back to Figure 1 and Figure 5, in block 108, a portion of the first metal foil 204 can be removed from the central region of the first glass substrate 200 to form a first hole 212 on the first glass substrate 200.

[0069] Referring back to Figure 1 and Figure 6, in block 110, the second surface 202b of the second glass substrate 202 contacts the first surface 214a of the second metal foil 214 to create a second contact position 216 between at least a portion of the second surface 202b of the second glass substrate 202 and the first surface 214a of the second metal foil 214. In an embodiment, the second metal foil 214 may have properties substantially similar to or the same as those of the first metal foil 204 previously described with reference to Figure 3.

[0070] Referring back to Figure 1 and also as shown in Figure 6, in block 112, a second welding step is performed by guiding a laser beam 208 over at least a portion of the second contact position 216 to bond the second glass substrate 202 and the second metal foil 214. In embodiments, the second welding step may utilize laser beam properties substantially similar to or the same as those of the laser beam 208 used in the first welding step previously described with reference to Figure 3. The laser beam 208 may traverse along the second contact position 216 to facilitate line bonding between the glass and the foil. For example, the laser beam may traverse along the second contact position 216 (e.g., entering and / or leaving this page and / or traversing the plane of the page in Figure 6) to facilitate line bonding between the glass and the foil.

[0071] In an embodiment, as shown in Figure 6, during the second welding step, the second glass substrate 202 may be optically positioned downstream of the first glass substrate 200 such that before the laser beam 208 is incident on the second contact position 216, the laser beam 208 travels through the first glass substrate 200 and then through the second glass substrate 202.

[0072] In an embodiment, the second adhesive position 218 may have a reduced maximum adhesive depth that is substantially similar to or the same as that of the first adhesive position 210 previously illustrated with reference to Figure 3.

[0073] As shown in Figures 3 and 6, the laser beam 208 can be guided at an angle of incidence θ relative to the first glass substrate 200 and the second glass substrate 202 (i.e., not orthogonal to the surfaces of the first and second glass substrates 202). By guiding the laser beam 208 through the first aperture 212 at an angle of incidence, the laser beam 208 can be incident on the contact position, which is at least partially obscured by the first metal foil 204 bonded in a direction orthogonal to the surfaces of the glass substrates. In embodiments, the angle of incidence θ can be less than or equal to 40°, less than or equal to 30°, less than or equal to 15°, or even less than or equal to 10°.

[0074] Referring now to Figure 7, in this embodiment, the lens or optical wedge 220 may be optically positioned upstream of both the first glass substrate 200 and the second glass substrate 202, such that the laser beam 208 travels through the lens or optical wedge 220 before passing through the first glass substrate 200 and the second glass substrate 202. As shown, the lens or optical wedge 220 may guide the laser beam 208 at an angle of incidence relative to the first glass substrate 200 and the second glass substrate 202.

[0075] Referring back to Figure 1 and Figure 8, in block 114, a portion of the second metal foil 214 can be removed from the central region of the second glass substrate 202 to form the second hole 222.

[0076] Referring back to Figure 1 and as shown in Figure 9, the first metal foil 204 and the second metal foil 214 can be sealed together to create an hermetically sealed package 224. In an embodiment, the hermetically sealed package 224 is created by bonding the first metal foil 204 and the second metal foil 214 to each other. In an embodiment, the hermetically sealed package 224 can be created by bonding the first metal foil 204 and the second metal foil 214 to each other and to an optional glass spacer (not shown) positioned between the first glass substrate 200 and the second glass substrate 202. In an embodiment, the hermetically sealed package 224 is created by bonding the first metal foil 204 and the second metal foil 214 to an optional glass spacer (not shown) positioned between the first glass substrate 200 and the second glass substrate 202. In an embodiment, sealing the first metal foil 204 and the second metal foil 214 can utilize a beam nature substantially similar to or the same as that of the laser beam 208 in the first welding step described above with reference to Figure 3. In an embodiment, the airtight sealed package may have a leakage rate of less than 1 x 10⁻¹⁰ atm-cc / s of air as measured by MIL-STD-750E test method 1071.9.

[0077] Referring now to Figures 10 and 11, an alternative process for laser bonding of glass and metal foil may involve mounting a first metal foil 204 onto a first glass substrate 200. A laser beam can be used to remove a portion 230 of the first metal foil 204, such as by laser ablation, as indicated by dashed line 232. Once the portion 230 is removed, a laser beam can then be used to bond the first metal foil 204 to the first glass substrate 200. The removal of a portion of the first metal foil 204 creates a region on the first metal foil 204 with reduced thickness, which allows for bonding of the metal foil and glass using a lower energy laser, thereby minimizing associated thermal defects in the region adjacent to this bonding.

[0078] Various modifications and variations may be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter, as will be apparent to those skilled in the art. Therefore, this specification is intended to cover modifications and variations to the various embodiments described herein, provided that such modifications and variations fall within the scope of the appended claims and their equivalents.

[0079] 100: Method Blocks 102, 104, 106, 108, 110, 112, 114, 116: 200: First glass substrate 200a: First surface 200b: Second surface 202: Second glass substrate 202a: First Surface 202b: Second Surface 204: First metal foil 204a: First surface 206: First contact position 208: Laser Beam 210: First bonding position 211: Maximum adhesion depth 212: First Hole 214: Second metal foil 214a: First surface 216: Second contact position 218: Second bonding position 220: Lens or optical wedge 222: Second hole 224: Airtight sealed packaging 230: Part 232: Dashed line

[0080] Domestic storage information (please note in order of storage institution, date, and number) none Overseas storage information (please note in the order of storage country, institution, date, and number) none

Claims

1. A method for laser bonding glass and metal foil, the method comprising the steps of: positioning a first surface of a first glass substrate adjacent to a first surface of a second glass substrate; contacting a second surface of the first glass substrate with a first surface of a first metal foil to create a first contact position between at least a portion of the second surface of the first glass substrate and the first surface of the first metal foil; performing a first welding step by guiding a laser beam over at least a portion of the first contact position to bond the first glass substrate to the first metal foil and form a first bonding position; contacting a second surface of the second glass substrate with a first surface of the second metal foil to create a second contact position between at least a portion of the second surface of the second glass substrate and the first surface of the second metal foil; and performing a second welding step by guiding a laser beam over at least a portion of the second contact position to bond the second glass substrate to the second metal foil and form a second bonding position, wherein the first metal foil and the second metal foil each have a diameter greater than or equal to 5 µm and a diameter less than or equal to 100 µm. A thickness of µm, wherein the laser beam includes a pulsed laser, the pulsed laser including: a pulse energy greater than or equal to 2.8 µJ and less than or equal to 1000 µJ; and a wavelength such that the first glass substrate and the second glass substrate are substantially transparent to the wavelength of the laser beam, and the first metal foil and the second metal foil are substantially opaque to the wavelength of the laser beam.

2. The method as described in claim 1, wherein at least one of the first adhesive location and the second adhesive location has a maximum adhesive depth of less than or equal to 20 µm.

3. The method as described in claim 1 or 2, wherein the first metal foil and the second metal foil are sealed to produce an airtight sealed package.

4. The method as described in claim 1 or 2, wherein the pulsed laser has a wavelength greater than or equal to 300 nm and less than or equal to 1100 nm.

5. The method as described in claim 1 or 2, wherein the pulsed laser is a nanosecond pulsed laser, a picosecond pulsed laser, or a femtosecond pulsed laser.

6. The method as described in claim 1 or 2, wherein the pulsed laser has a repetition rate greater than or equal to 5 kHz and less than or equal to 1 MHz.

7. The method as described in claim 1 or 2, wherein the pulsed laser has a spot size greater than or equal to 5 µm and less than or equal to 50 µm.

8. The method as described in claim 1 or 2, wherein the laser beam is guided at an oblique angle of incidence relative to the first glass substrate and the second glass substrate.

9. The method as described in claim 8, wherein the tilted angle of incidence is less than or equal to 30°.

10. The method of claim 8, wherein a lens is optically positioned upstream of both the first glass substrate and the second glass substrate, such that the laser beam travels through the lens before traveling through the first glass substrate and the second glass substrate.

11. The method as claimed in claim 1 or 2, wherein during the first welding step, the first glass substrate is optically positioned downstream of the second glass substrate such that the laser beam travels through the second glass substrate and then through the first glass substrate before being incident on the first contact position.

12. The method as claimed in claim 1 or 2, wherein during the second welding step, the second glass substrate is optically positioned downstream of the first glass substrate such that the laser beam travels through the first glass substrate and then through the second glass substrate before being incident on the second contact position.

13. The method as claimed in claim 1 or 2, wherein during the first welding step, the first metal foil is optically positioned upstream of the first glass substrate such that the laser beam contacts the first metal foil to bond the first metal foil to the first glass substrate.

14. The method as described in claim 13, wherein the laser beam removes a portion of the first metal foil before bonding the first metal foil to the first glass substrate.

15. The method as described in claim 1 or 2, wherein the first glass substrate and the second glass substrate have a refractive index greater than or equal to 1.5 and less than or equal to 2.

4.

16. The method as described in claim 1 or 2, wherein the first glass substrate and the second glass substrate comprise a glass, a ceramic, or a glass-ceramic, wherein the glass, the ceramic, or the glass-ceramic comprises borate glass, silicate borate glass, phosphate glass, silicate carbide glass, sodium-calcium silicate glass, aluminosilicate glass, alkali metal aluminosilicate glass, borosilicate glass, alkali metal borosilicate glass, aluminosilicate glass, alkali metal aluminosilicate glass, alkali metal aluminosilicate glass, or sapphire.

17. The method as described in claim 1 or 2, wherein at least one of the first metal foil and the second metal foil comprises aluminum, aluminum alloy, stainless steel, nickel, nickel alloy, silver, silver alloy, titanium, titanium alloy, tungsten, tungsten alloy, gold, gold alloy, copper, copper alloy, bronze, iron, or a combination of the foregoing.

18. The method as described in claim 1 or 2, wherein at least one of the first metal foil and the second metal foil has a melting point of less than or equal to 1600 °C.

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