CN117916047A - Laser bonding of glass to thin metal foil - Google Patents

Abstract

A method of laser bonding glass to a metal foil includes contacting a first glass substrate with a first metal foil to create a first contact location; directing a laser beam at a first contact location to bond a first glass substrate to a first metal foil; contacting the second glass substrate with the second metal foil to create a second contact location; and directing a laser beam at the second contact location to bond the second glass substrate to the second metal foil, wherein the first metal foil and the second metal foil each have a thickness from 5 μm to 100 μm, and wherein the laser beam comprises a pulsed laser comprising: 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

Laser bonding of glass to thin metal foil

Technical Field

The present disclosure is based on the priority rights of U.S. provisional application No. 63/238515, filed 8/30 of patent statutes, and U.S. provisional application No. 63/274984, filed 11/3 of 2021, each of which is incorporated herein by reference in its entirety.

The present description relates generally to glass bonded to metal foil, and more particularly to laser bonding of glass to thin metal foil.

Background

Hermetically (HERMETICALLY) bonded glass and metal foil packages are increasingly popular for use in electronic and other devices that can benefit from a hermetic environment for continued operation. However, conventional laser bonding processes can cause undesirable heat-related defects in the areas adjacent to the bond.

Accordingly, there is a need for alternative methods of creating laser bonded glass and metal foil packages while minimizing thermal defects in the areas adjacent to the bond.

Disclosure of Invention

According to a first aspect A1, a method of laser bonding glass to metal foil may comprise: positioning a first surface of a first glass substrate adjacent to a first surface of a second glass substrate; contacting the second surface of the first glass substrate with the first surface of the first metal foil to create a first contact location 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 directing a laser beam over at least a portion of the first contact location to bond the first glass substrate to the first metal foil and form a first bond location; contacting the second surface of the second glass substrate with the first surface of the second metal foil to create a second contact location 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 directing a laser beam over at least a portion of the second contact location to bond the second glass substrate to the second metal foil and form a second bonding location, 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 comprises a pulsed laser comprising: 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.

The second aspect A2 comprises the method according to the first aspect A1, wherein at least one of the first bonding location and the second bonding location has a maximum bonding depth of less than or equal to 20 μm.

The third aspect A3 comprises the method according to the first aspect A1 or the second aspect A2, wherein the first metal foil and the second metal foil are sealed to produce a hermetically sealed package (HERMETICALLY SEALED PACKAGE).

The fourth aspect A4 includes the method according to any one of the first to third aspects A1 to A3, wherein the pulsed laser light has a wavelength of greater than or equal to 300nm and less than or equal to 1100 nm.

The fifth aspect A5 includes the method according to any one of the first to fourth aspects A1 to A4, wherein the pulsed laser is a nanosecond pulsed laser, a picosecond pulsed laser, or a femtosecond pulsed laser.

A sixth aspect A6 includes the method according to any one of the first to fifth aspects A1-A5, wherein the pulsed laser has a repetition rate of greater than or equal to 5kHz and less than or equal to 1 MHz.

The seventh aspect A7 includes the method according to any one of the first to sixth aspects A1-A6, wherein the pulsed laser has a spot size (spot size) of greater than or equal to 5 μm and less than or equal to 50 μm.

An eighth aspect A8 includes the method according to any one of the first to seventh aspects A1-A7, wherein the laser beam is directed at an oblique incident angle with respect to the first glass substrate and the second glass substrate.

The ninth aspect A9 includes the method according to the eighth aspect A8, wherein the oblique incident angle is less than or equal to 30 °.

The tenth aspect a10 includes the method according to the eighth aspect A8 or the ninth aspect A9, wherein a lens is optically disposed 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.

An eleventh aspect a11 includes the method according to any one of the first to tenth aspects A1-a10, wherein during the first fusion bonding 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 the laser beam reaches the first contact position.

A twelfth aspect a12 includes the method according to any one of the first to eleventh aspects A1-a11, wherein during the second fusion bonding 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 the laser beam reaches the second contact position.

The thirteenth aspect a13 includes the method according to any one of the first to seventh aspects A1-A7, wherein during the first fusing 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.

A fourteenth aspect a14 includes the method according to the thirteenth aspect a13, wherein the laser beam removes a portion of the first metal foil before bonding the first metal foil to the first glass substrate.

The fifteenth aspect a15 includes the method according to any one of the first to fourteenth aspects A1 to a14, wherein the first glass substrate and the second glass substrate include refractive indices of 1.5 or more and 2.4 or less.

A sixteenth aspect a16 includes the method according to any one of the first to fifteenth aspects A1-a15, wherein the first glass substrate and the second glass substrate comprise glass, glass ceramic, or ceramic, the glass, glass ceramic, or ceramic comprises borate glass, borosilicate glass, phosphate-based glass, silicon carbide glass, soda lime silicate glass, aluminosilicate glass, alkali aluminosilicate glass, borosilicate glass, alkali borosilicate glass, aluminoborosilicate glass, alkali aluminosilicate glass, or sapphire.

The seventeenth aspect a17 includes the method according to any one of the first to sixteenth aspects A1-a16, wherein at least one of the first metal foil and the second metal foil comprises aluminum, an aluminum alloy, stainless steel, nickel, a nickel alloy, silver, a silver alloy, titanium, a titanium alloy, tungsten, a tungsten alloy, gold, a gold alloy, copper, a copper alloy, bronze, iron, or a combination of the foregoing.

An eighteenth aspect a18 includes the method according to any one of the first to seventeenth aspects A1-a17, wherein at least one of the first metal foil and the second metal foil includes a melting point of less than or equal to 1600 ℃.

Additional features and advantages of the laser bonding methods described herein will be set forth in the description which follows, and in part will be apparent to those having ordinary skill in the art from the description or recognized by practicing the embodiments described herein, including the description which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following embodiments describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. 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 various embodiments described herein and, together with the description, serve to explain the principles and operation of the claimed subject matter.

Drawings

FIG. 1 is a flow chart of a method of laser bonding glass and metal foil according to one or more embodiments shown and described herein;

FIG. 2 schematically depicts a step of a laser bonding method according to one or more embodiments shown and described herein;

FIG. 3 schematically depicts another step of a laser bonding method according to one or more embodiments shown and described herein;

FIG. 4 is a scanning electron microscope image of a metal foil bonded to glass according to one or more embodiments shown and described herein;

FIG. 5 schematically depicts another step of a laser bonding method according to one or more embodiments shown and described herein;

FIG. 6 schematically depicts another step of a laser bonding method according to one or more embodiments shown and described herein;

FIG. 7 schematically depicts an alternative step of a laser bonding method according to one or more embodiments shown and described herein;

FIG. 8 schematically depicts another step of a laser bonding method according to one or more embodiments shown and described herein;

FIG. 9 schematically depicts another step of a laser bonding method according to one or more embodiments shown and described herein;

FIG. 10 schematically depicts a step of an alternative laser bonding method according to one or more embodiments shown and described herein; and

Fig. 11 schematically depicts another step of an alternative laser bonding method according to one or more embodiments shown and described herein.

Detailed Description

Reference will now be made in detail to various embodiments of a method of laser bonding glass to metal foil while minimizing associated thermal defects in the region adjacent to such bonding. According to an embodiment, a method of 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 the second surface of the first glass substrate with the first surface of the first metal foil to create a first contact location 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 directing a laser beam over at least a portion of the first contact location to bond the first glass substrate to the first metal foil and form a first bond location; contacting the second surface of the second glass substrate with the first surface of the second metal foil to create a second contact location 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 directing a laser beam over at least a portion of the second contact location to bond the second glass substrate to the second metal foil and form a second bonding location. The first metal foil and the second metal foil each have a thickness of 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 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. Various embodiments of laser bonding glass and metal foil and packages formed therefrom will be described with particular reference to the accompanying drawings.

Ranges may be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

Directional terms used herein, such as up, down, right, left, front, rear, top, bottom, are merely made with reference to the depicted illustrations and are not intended to imply absolute orientations.

Unless explicitly stated otherwise, it is in no way intended that any method described herein be construed as requiring any device whose steps are performed in a particular order, or that requires a particular orientation. Thus, when a method claim does not actually describe the order in which the steps are followed, or any apparatus claim does not actually describe the order or the orientation of the individual components, or it is not otherwise clear that the steps are limited to a specific order or orientation of the components of the apparatus in the claims or the description, it is in no way intended that the order or orientation be inferred in any respect. This state applies to any possible non-descriptive basis for interpretation, including: logic matters concerning the arrangement of steps, operational flows, sequence of components, or orientation of components; the plain meaning derived from grammatical structures or punctuation, and the number or type of embodiments described in this specification.

As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a" or "an" component includes aspects having two or more such components unless the context clearly indicates otherwise.

As used herein, "hermetically bonded (HERMETICALLY BONDED)" or "hermetically sealed (HERMETICALLY SEALED)" refers to a package comprising a hermetic seal according to MIL-STD-750E, test method 1071.9.

The "maximum adhesion depth" described herein and determined using a scanning electron microscope refers to the depth in the thickness direction of the glass substrate/metal foil interface, which may be partially exhibited within the glass substrate and partially exhibited within the metal foil, as shown in fig. 4.

The hermetically bonded glass and metal foil packages may be used in devices that may benefit from the hermetically sealed package, such as televisions, sensors, optical devices, organic Light Emitting Diode (OLED) displays, 3D inkjet printers, solid state light sources, batteries, and photovoltaic structures. Conventional laser bonding processes involve the use of high energy lasers to bond thick metal foils (e.g., foils having a thickness greater than 50 μm) to glass. However, heating using a high energy laser can cause associated thermal defects (e.g., cracking) in the region adjacent to this bond.

Disclosed herein are methods of laser bonding glass to metal foil that alleviate the aforementioned problems such that the associated thermal defects in the area adjacent to such bonding are minimized. Specifically, the methods of laser bonding glass to metal foil disclosed herein utilize a lower energy laser to bond a thin metal foil (e.g., a 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 having a reduced maximum bond depth (e.g., a bond depth of less than or equal to 20 μm or less than or equal to 10 μm).

Referring now to fig. 1 and 2, a method 100 of laser bonding glass and metal foil begins at block 102 with positioning a first glass substrate 200 with a second glass substrate 202. 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, 202 a.

The first surface 200a of the first glass substrate 200 is placed adjacent to the first surface 202a of the second glass substrate 202. In embodiments, as illustrated, the first and second glass substrates 200, 202 may not be in direct contact with each other such that one or more other glass substrates or components (e.g., electronic components) may be placed therein to protect additional substrates or components from different environmental conditions, such as pressure changes, humidity, bulk fluid (bodily fluid), 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 embodiments, the first glass substrate 200 and the second glass substrate 202 may be a single substrate having a cavity (e.g., formed from an edge) sealed as described herein.

In an embodiment, the first and second glass substrates 200, 202 may include a refractive index greater than or equal to 1.5 and less than or equal to 2.4. In embodiments, the first and second glass substrates 200, 202 may include a refractive index 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 embodiments, the first and second glass substrates 200, 202 may include a refractive index 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, 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 2.2, 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, and equal to 2.3, or equal to 1.8, and equal to 2.3, and any of these endpoints.

In an embodiment, 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 fully or substantially fully ceramized such that they comprise a ceramic material. As non-limiting examples, the first and second glass substrates 200, 202 may include borate glass, borosilicate glass, phosphate-based glass, silicon carbide glass, soda lime silicate glass, aluminosilicate glass, alkali aluminosilicate glass, borosilicate glass, alkali borosilicate glass, aluminoborosilicate glass, alkali aluminosilicate glass, or sapphire. In embodiments where relatively high index glass is desired (e.g., 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, which is incorporated herein by reference in its entirety. 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 from corning corporationLotus^TM、/>Glasses, including chemically strengthened, chemically tempered, and/or thermally tempered versions of these glasses. In embodiments, glasses and glass ceramics that have been chemically strengthened by ion exchange may be suitable for use as substrates. In other embodiments, the first and/or second glass substrates 200, 202 may be strengthened glass-to-glass laminates.

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

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

In an embodiment, the first and second glass substrates 200, 202 may be subjected to surface preparation prior to bonding of the glass substrates to the metal foil. For example, in embodiments, the first and second glass substrates 200, 202 may be polished until their surfaces exhibit a comparatively lower surface roughness value, which may enhance adhesion. In embodiments, 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) of 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 may allow the first and second glass substrates to be placed in intimate contact with the metal foil (e.g., within a few μm of each other). In addition, the first and second glass substrates 200, 202 may be rinsed with water and/or solvents to remove any debris present on such surfaces and/or to remove any materials (oils, fats, etc.) that would reduce the transparency of the substrate to the desired laser wavelength. The removal of any debris may allow the first and second glass substrates to be placed in intimate contact with the metal foil to better facilitate laser bonding of the metal foil to the glass.

Referring back to fig. 1 and as shown in fig. 3, at 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 location 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.

In an embodiment, the first metal foil 204 may have a thickness of less than or equal to 100 μm. In an embodiment, the first metal foil 204 may have a thickness of greater than or equal to 5 μm and less than or equal to 100 μm. In embodiments, 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 embodiments, the first metal foil 204 may have a thickness of 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 embodiments, the first metal foil 204 may have a thickness of 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 sub-ranges formed by any of these endpoints.

In the present embodiment of the present invention, the first metal foil 204 may comprise aluminum, aluminum alloy, stainless steel, nickel alloy, silver alloy, titanium titanium alloy, tungsten alloy, gold alloy, 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.

In an embodiment, the first metal foil 204 may be formed of a material having a melting point that allows successful adhesion to a glass substrate. In an embodiment, the first metal foil 204 may include a melting point of less than or equal to 1600 ℃, less than or equal to 1500 ℃, and less than or equal to 1400 ℃.

In an embodiment, the first metal foil 204 may be formed of a material that is chemically compatible (i.e., readily bondable) with the glass substrate. For example, a glass substrate including aluminum may be more easily bonded to an aluminum metal foil.

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 when the laser beam contacts the material, the wavelength of the laser beam is substantially absorbed. For example, in an embodiment, a material that is substantially opaque to the wavelength of the laser beam may be a material that exhibits an absorptivity at this wavelength of greater than or equal to 35%.

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

Referring back to fig. 1 and as shown in fig. 3, at block 106, a first fusion step is performed to bond the first glass substrate 200 and the first metal foil 204 by directing a laser beam 208 over at least a portion of the first contact location 206.

In an embodiment, the laser beam 208 comprises a pulsed laser. In an embodiment, the pulsed laser may be a nanosecond pulsed laser, a picosecond pulsed laser, or a femtosecond pulsed laser.

The laser bonding method described herein utilizes a lower energy laser to bond the metal foil to the glass, thereby minimizing the associated thermal defects in the vicinity. In embodiments, the pulsed laser may include a pulse energy greater than or equal to 2.8 μj and less than or equal to 1000 μj. In embodiments, the pulsed laser may comprise a pulse energy 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 comprise a pulse energy of 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 the present embodiment of the present invention, the pulsed laser may comprise pulse energies of 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 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 the endpoints of these endpoints.

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

In embodiments, the pulsed laser may comprise a highly repetitive pulsed UV laser operating at about 355nm, 532nm, 1064nm or any other wavelength suitable depending on the penetration of the glass.

In an embodiment, the pulsed laser may have a repetition rate of greater than or equal to 5kHz and less than or equal to 1MHz. In embodiments, the pulsed laser may have a repetition rate of greater than or equal to 5kHz, greater than or equal to 50kHz, greater than or equal to 100kHz, or even greater than or equal to 250kHz. In embodiments, the pulsed laser may have a repetition rate of less than or equal to 1MHz, less than or equal to 750kHz, or even less than or equal to 500kHz. In embodiments, the pulsed laser may have a repetition rate of greater than or equal to 5kHz and less than or equal to 1MHz, greater than or equal to 5kHz and less than or equal to 750kHz, greater than or equal to 5kHz and less than or equal to 500kHz, greater than or equal to 50kHz and less than or equal to 1MHz, greater than or equal to 50kHz and less than or equal to 750kHz, greater than or equal to 50kHz and less than or equal to 500kHz, greater than or equal to 100kHz and less than or equal to 1MHz, greater than or equal to 100kHz and less than or equal to 750kHz, greater than or equal to 100kHz and less than or equal to 500kHz, greater than or equal to 250kHz and less than or equal to 1MHz, greater than or equal to 250kHz and less than or equal to 750kHz, or even greater than or equal to 250kHz and less than or equal to 500kHz, or any and all sub-ranges formed by any of these endpoints.

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 embodiments, 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 embodiments, 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 embodiments, the pulsed laser may have spot sizes 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 20 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 35 μm, or even greater than or equal to 10 μm and less than or equal to 20 μm, or any and all subranges formed by any of these endpoints.

In an embodiment, as shown in fig. 3, during the first fusion 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, however through the first glass substrate 200, before the laser beam 208 is incident on the first contact location 206. The laser beam 208 may traverse along the first contact location 206 to promote line adhesion between the glass and the foil. For example, the laser beam may traverse (e.g., into and/or out of such a page and/or transverse to the plane of the page in fig. 3) along the first contact location 206 to promote line adhesion between the glass and the foil.

As described herein, the methods of laser bonding glass and metal foil disclosed herein utilize a lower energy laser to minimize associated thermal defects in the region adjacent to such bonding by reducing the maximum bond depth (i.e., reduced maximum bond depth 211 is less than or equal to 20 μm), as shown in fig. 4. Referring back to fig. 3, in embodiments, the first bond site 210 may have a maximum bond depth of 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 bond depth or portion thereof that is exhibited within the glass substrate (e.g., excluding any portion of the bond that is exhibited 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.

Referring back to fig. 1 and as shown in fig. 5, at block 108, a portion of the first metal foil 204 may be removed from the central region of the first glass substrate 200 to form a first hole 212 in the first glass substrate 200.

Referring back to fig. 1 and as shown in fig. 6, at 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 location 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 embodiments, the second metal foil 214 may have substantially similar or identical properties as the first metal foil 204 described herein before with reference to fig. 3.

Referring back to fig. 1 and also to fig. 6, at block 112, a second fusion step is performed by directing the laser beam 208 over at least a portion of the second contact location 216 to bond the second glass substrate 202 to the second metal foil 214. In embodiments, the second welding step may utilize substantially similar or identical laser beam properties as the laser beam 208 of the first welding step described hereinabove with reference to fig. 3. The laser beam 208 may traverse along the second contact location 216 to promote line adhesion between the glass and the foil. For example, the laser beam may traverse (e.g., into and/or out of such a page and/or transverse to the plane of the page in fig. 6) along the second contact location 216 to promote line adhesion between the glass and the foil.

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

In an embodiment, the second bond site 218 may have a reduced maximum bond depth substantially similar or identical to the first bond site 210 described hereinabove with reference to fig. 3.

As shown in fig. 3 and 6, the laser beam 208 may be directed at an oblique angle of incidence θ with respect to the first and second glass substrates 200 and 202 (i.e., non-orthogonal to the surfaces of the first and second glass substrates 202). By directing the laser beam 208 through the first aperture 212 at an oblique angle of incidence, the laser beam 208 may be incident on a contact location that may be at least partially obscured by the first metal foil 204 bonded in a direction normal to the surface of the glass substrate. In embodiments, the oblique incidence angle θ may 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 °.

Referring now to fig. 7, in an embodiment, a lens or 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 wedge 220 before traveling through the first glass substrate 200 and the second glass substrate 202. As illustrated, a lens or wedge 220 may direct the laser beam 208 relative to the oblique angles of incidence of the first glass substrate 200 and the second glass substrate 202.

Referring back to fig. 1 and as shown in fig. 8, at block 114, a portion of the second metal foil 214 may be removed from the central region of the second glass substrate 202 to form a second hole 222.

Referring back to fig. 1 and as shown in fig. 9, the first metal foil 204 and the second metal foil 214 may be sealed together to create a hermetically sealed package 224. In an embodiment, hermetically sealed package 224 is created by joining first metal foil 204 and second metal foil 214 to one another. In an embodiment, hermetically sealed package 224 may be created by bonding first metal foil 204 and second metal foil 214 to each other and to an optional glass spacer (not depicted) positioned between first glass substrate 200 and second glass substrate 202. In an embodiment, hermetically sealed package 224 is created by bonding first and second metal foils 204, 214 to an optional glass spacer (not depicted) positioned between first and second glass substrates 200, 202. In embodiments, sealing the first metal foil 204 and the second metal foil 214 may utilize beam properties substantially similar or identical to the laser beam 208 of the first welding step described above with reference to fig. 3. In an embodiment, the hermetically sealed package may have an air leakage rate less than the test detectability of 1x 10 ^-10 atm-cc/sec as measured by MIL-STD-750E test method 1071.9.

Referring now to fig. 10 and 11, an alternative process of laser bonding glass and metal foil may include mounting a first metal foil 204 on a first glass substrate 200. A laser beam may 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 may 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 of reduced thickness on the first metal foil 204 that thereby may enable the use of a lower energy laser to bond the metal foil to the glass, thereby minimizing associated thermal defects in the region adjacent to such bonding.

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 of ordinary skill in the art. Accordingly, it is intended that the present specification cover the modifications and variations of the various embodiments described herein provided such modifications and variations come within the scope of the appended claims and their equivalents.

Claims (18)

1. A method of laser bonding glass to a metal foil, the method comprising:

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 location 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 directing a laser beam over at least a portion of the first contact location to bond the first glass substrate to the first metal foil and form a first bonding location;

contacting a second surface of the second glass substrate with a first surface of a second metal foil to create a second contact location between at least a portion of the second surface of the second glass substrate and the first surface of the second metal foil; and

A second welding step is performed by directing the laser beam over at least a portion of the second contact location to bond the second glass substrate to the second metal foil and form a second bonding location,

Wherein the first metal foil and the second metal foil each have a thickness of greater than or equal to 5 μm and less than or equal to 100 μm, and

Wherein the laser beam comprises a pulsed laser comprising:

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.

2. The method of claim 1, wherein at least one of the first bonding location and the second bonding location has a maximum bonding depth of less than or equal to 20 μιη.

3. The method of claim 1 or 2, wherein the first metal foil and the second metal foil are sealed to create a hermetically sealed package.

4. A method as claimed in any one of claims 1 to 3, wherein the pulsed laser has a wavelength greater than or equal to 300nm and less than or equal to 1100 nm.

5. The method of any one of claims 1 to 4, wherein the pulsed laser is a nanosecond pulsed laser, a picosecond pulsed laser, or a femtosecond pulsed laser.

6. The method of any one of claims 1 to 5, wherein the pulsed laser has a repetition rate of greater than or equal to 5kHz and less than or equal to 1 MHz.

7. The method of any one of claims 1 to 6, wherein the pulsed laser has a spot size greater than or equal to 5 μιη and less than or equal to 50 μιη.

8. The method of any one of claims 1 to 7, wherein the laser beam is directed at an oblique angle of incidence relative to the first glass substrate and the second glass substrate.

9. The method of claim 8, wherein the oblique incident angle is less than or equal to 30 °.

10. The method of claim 8 or 9, 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 of any one of claims 1 to 10, wherein during the first fusing 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 the laser beam is incident on the first contact location.

12. The method of any one of claims 1 to 11, wherein during the second fusing 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 the laser beam is incident on the second contact location.

13. The method of any one of claims 1 to 7, wherein during the first fusing 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 of claim 13, wherein the laser beam removes a portion of the first metal foil prior to bonding the first metal foil to the first glass substrate.

15. The method of any one of claims 1-14, wherein the first glass substrate and the second glass substrate comprise a refractive index greater than or equal to 1.5 and less than or equal to 2.4.

16. The method of any one of claims 1-15, wherein the first glass substrate and the second glass substrate comprise a glass, a ceramic, or a glass-ceramic, the glass, the ceramic, or the glass-ceramic comprising a borate glass, a borosilicate glass, a phosphate-based glass, a silicon carbide glass, a soda lime silicate glass, an aluminosilicate glass, an alkali aluminosilicate glass, a borosilicate glass, an alkali borosilicate glass, an aluminoborosilicate glass, an alkali aluminosilicate glass, or sapphire.

17. The method of any one of claims 1-16, wherein at least one of the first metal foil and the second metal foil comprises aluminum, an aluminum alloy, stainless steel, nickel, a nickel alloy, silver, a silver alloy, titanium, a titanium alloy, tungsten, a tungsten alloy, gold, a gold alloy, copper, a copper alloy, bronze, iron, or a combination of the foregoing.

18. The method of any one of claims 1-17, wherein at least one of the first metal foil and the second metal foil comprises a melting point of less than or equal to 1600 ℃.