CN116670082A

CN116670082A - Cover glass with outer frame

Info

Publication number: CN116670082A
Application number: CN202180087136.9A
Authority: CN
Inventors: 熊谷茉利奈
Original assignee: Asahi Glass Co Ltd
Current assignee: AGC Inc
Priority date: 2020-12-23
Filing date: 2021-12-17
Publication date: 2023-08-29
Also published as: WO2022138518A1; TW202226465A; JPWO2022138518A1

Abstract

The present invention relates to a cover glass comprising an outer frame made of a glass ceramic having a filler component dispersed in a glass matrix, wherein the glass softening point of the glass matrix contained in the glass ceramic is lower than the glass transition point of a plate-like glass having a thermal expansion coefficient equal to or higher than that of the glass ceramic, and the difference between the glass softening point and the glass softening point is 0 to 20X 10 ^－7 And (3) at a temperature of DEG C, the plate-like glass is directly bonded to the glass ceramic.

Description

Cover glass with outer frame

Technical Field

The invention relates to cover glass with an outer frame.

Background

Devices using light emitting diodes (LEDs: light Emission Diode) have been used for a wide variety of applications such as mobile phones, backlights for large liquid crystal televisions, lighting applications, and the like.

For example, in the case of a light-emitting device using a light-emitting diode (visible light LED) that emits visible light, a structure is often employed in which an LED chip is mounted on a flat substrate typified by aluminum nitride and sealed with a resin matrix member.

In contrast, in a light-emitting device using a light-emitting diode (UV-LED) that emits ultraviolet light, a Laser Diode (LD), a Vertical Cavity Surface Emitting Laser (VCSEL), or the like, hermetic sealing is required. In addition, a diffusion plate is also required in the VCSEL.

Therefore, in these light emitting devices, a cover glass is required to have a shape of an outer frame. Although the outer frame may be provided on a substrate such as aluminum nitride, it is more practical to provide the outer frame on the cover glass from the viewpoint of cost.

In manufacturing cover glass with an outer frame, the simplest method is a method of separately manufacturing cover glass and glass for an outer frame and bonding them with a resin matrix member. However, for the adhesion of the resin matrix member using an organic substance, airtight sealing cannot be achieved.

In order to obtain the airtight sealing, a method of forming an outer frame portion by directly wet etching glass is exemplified. However, perpendicularity between the flat plate-like portion and the portion serving as the outer frame is not obtained. Accordingly, in order to obtain airtight sealing while maintaining the perpendicularity, a flat glass is directly bonded to glass serving as an outer frame by diffusion bonding, room temperature bonding, or the like. On the other hand, direct bonding is very costly.

In view of this, various studies have been made and a technique of providing an outer frame on a glass substrate has been proposed.

For example, patent document 1 discloses a synthetic quartz glass cavity in which a plurality of through holes are formed in a raw synthetic quartz glass substrate by sand blast processing. The synthetic quartz glass substrate is bonded to another synthetic quartz glass substrate, and bonded at 1000 to 1200 ℃.

Patent document 2 discloses a framed antireflection glass using borosilicate glass as a flat plate-like member and a silicon substrate as a frame-like member. The above-mentioned framed antireflection glass is obtained by forming a through hole by reactive ion etching of a silicon substrate, overlapping a frame-like member and a plate-like member, and joining the two members by anodic bonding.

Patent document 3 discloses a glass sealing material in which a glass plate and a glass sheet are joined by fusion bonding by sandwiching and hot-pressing a glass plate and a glass sheet base mold frame and an opposing mold frame.

Patent document 4 discloses an airtight container in which a paste such as a frit having a lower softening point than a glass substrate is screen-printed on the glass substrate and a bonding material formed by the paste is used as a frame member.

Patent document 5 discloses a method in which a glass substrate having a partition wall is obtained by filling a paste made of a heat-curable composition containing a glass powder into a mold frame or by pressing and heating a sheet made of a heat-curable composition containing a glass powder against a mold frame.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2020-21937

Patent document 2: japanese patent No. 5646981

Patent document 3: japanese patent application laid-open No. 2013-222522

Patent document 4: japanese patent laid-open publication No. 2011-233479

Patent document 5: japanese patent laid-open publication No. 2005-243454

Disclosure of Invention

However, according to the methods described in patent documents 1 and 3, if heat is applied at a temperature exceeding the glass softening point of the glass material used, the surface of the glass is damaged, and there is a concern about reliability. According to the method described in patent document 2, if the thermal expansion coefficients of the flat plate-like member and the frame-like member are different, cracks may occur in the glass that is the flat plate-like member. In addition, the cost of anodic bonding is also high. According to the method described in patent document 4, when the paste is applied, there is a concern that sealability is lowered due to uneven application and uneven film thickness. In the method described in patent document 5, the height of the partition wall as the outer frame is limited to about 150 μm as an upper limit.

Accordingly, an object of the present invention is to provide a cover glass with an outer frame that can achieve a predetermined or more outer frame height while maintaining airtight sealing properties and that reduces damage and cracking on the surface of the cover glass.

The present inventors have conducted intensive studies and as a result, have found that the above problems can be solved by using a specific glass ceramic for the outer frame, and have completed the present invention.

That is, the present invention and one embodiment thereof are described in the following [1] to [9].

[1]A cover glass with an outer frame comprising a cover glass having an outer frame provided on one main surface of a plate-like glass, wherein the outer frame is made of a glass ceramic having a filler component dispersed in a glass matrix, the glass softening point of the glass matrix contained in the glass ceramic is lower than the glass transition point of the plate-like glass, the thermal expansion coefficient of the plate-like glass is a value equal to or higher than the thermal expansion coefficient of the glass ceramic, and the difference between the two is 0 to 20X 10 ^－7 And (3) at a temperature of DEG C, the plate-like glass is directly bonded to the glass ceramic.

[2] The cover glass with an outer frame according to the above [1], wherein the glass base contains at least one of bismuth oxide and boron oxide.

[3] The cover glass with an outer frame according to the above [1] or [2], wherein the glass ceramic contains 5 to 40 mass% of a crystal powder containing alumina as the filler component.

[4] The cover glass with an outer frame according to any one of [1] to [3], wherein a metal film is formed on a surface of the outer frame facing a surface to which the flat glass is bonded.

[5] The cover glass with an outer frame according to any one of the above [1] to [4], wherein the outer frame is provided perpendicularly to the flat glass.

[6] The cover glass with an outer frame according to any one of the above [1] to [5], wherein the height of the outer frame is 350 μm to 1.5mm.

[7] The cover glass with an outer frame according to any one of [1] to [6], wherein the flat glass has a conductive film in at least a partial region of a main surface of a side to which the outer frame is joined, a metal conductor penetrating the outer frame is formed in the outer frame, the metal conductor is disposed perpendicular to the flat glass, and the conductive film is in conduction with the metal conductor.

[8] The cover glass with an outer frame according to any one of [1] to [7], wherein the flat glass has an antireflection film on at least one main surface.

[9] The cover glass with an outer frame according to any one of [1] to [8], wherein the flat glass has a light diffusion layer on at least one main surface.

According to the present invention, in the cover glass with the outer frame, the height of the outer frame can be made to be equal to or higher than a predetermined level while maintaining the airtight sealing property. Therefore, damage to the cover glass due to energy of the UV-LED, LD (laser diode) or the like as a light source can be prevented. In addition, since the surface of the cover glass is not damaged or cracked by heat, the reliability as the cover glass with the outer frame is very high. The reliability refers to the concept of the above-mentioned aspects of the heat shock resistance, chemical resistance, verticality, and the like under high temperature and high humidity in addition to the airtight sealability.

Drawings

Fig. 1 is a schematic cross-sectional view showing an example of cover glass with an outer frame according to the present embodiment.

Fig. 2 is a schematic cross-sectional view showing an example of the cover glass with an outer frame according to the present embodiment.

Fig. 3 is a schematic cross-sectional view showing an example of the cover glass with an outer frame according to the present embodiment.

Detailed Description

The present invention will be described in detail below, but the present invention is not limited to the following embodiments, and may be implemented by any modification within the scope of the present invention. The terms "to" representing the numerical range are used in a meaning including the numerical values described before and after the term "to" as the lower limit value and the upper limit value. The term "mass%" is the same as "weight%".

< cover glass with outer frame >)

As shown in fig. 1, the cover glass with an outer frame 10 of the present embodiment is provided with an outer frame 2 on one main surface of a flat glass 1. The outer frame 2 is formed along the outer edge of the flat glass 1.

The outer frame 2 is made of glass ceramic in which a filler component is dispersed in a glass matrix, and the flat glass 1 is directly bonded to the glass ceramic as the outer frame 2.

The glass softening point Ts of the glass matrix contained in the glass ceramic is lower than the glass transition point Tg of the flat glass 1. The thermal expansion coefficient of the flat glass 1 is equal to or higher than that of glass ceramics, and the difference between them is 0 to 20×10 ^－7 /℃。

A good airtight seal is obtained by directly bonding a flat glass to an outer frame. The direct bonding is a state in which the flat glass and the outer frame are bonded without an adhesive layer of an organic material such as a resin layer other than the flat glass and the outer frame. In the case where a conductive film as an inorganic material to be described later is formed on the main surface of the flat glass, the flat glass is bonded to the outer frame via the conductive film. In this case, the conductive film is treated as a structure made of an inorganic material integrated with the plate glass, and one mode of directly bonding the plate glass and the outer frame is adopted. In addition, even when the plate glass and the outer frame are directly bonded, the plate glass and the outer frame can be bonded by simply overlapping and heating the plate glass and the outer frame without applying a voltage such as anodic bonding.

Whether or not the bonding is direct can be determined based on the absence of the adhesive layer between the flat glass and the outer frame.

For the glass ceramic used as the outer frame, the glass softening point Ts of the glass matrix constituting the glass ceramic is lower than the glass transition point Tg of the plate-like glass. This makes it possible to join the sheet glass directly without damaging the surface of the sheet glass at high temperature.

From the viewpoint of preventing damage to the surface of the plate-like glass, the difference between the glass transition point Tg of the plate-like glass and the glass softening point Ts of the glass base is preferably 50 ℃ or higher, more preferably 65 ℃ or higher, and still more preferably 85 ℃ or higher. On the other hand, from the viewpoint of suppressing an increase in carbon residue at the time of firing the glass ceramic to be the outer frame, and thereby inhibiting the insulation property, the difference is preferably 180 ℃ or less, more preferably 130 ℃ or less, and still more preferably 100 ℃ or less.

The difference between the glass transition point Tg of the flat glass and the glass softening point Ts of the glass substrate is preferably in the above range, specifically, preferably 550 ℃ or higher, more preferably 600 ℃ or higher, still more preferably 650 ℃ or higher, and more preferably higher. On the other hand, from the viewpoint of ease of processing, the glass transition point Tg of the plate glass is preferably 1000 ℃ or lower, more preferably 900 ℃ or lower, and still more preferably 800 ℃ or lower. The glass transition point Tg of the plate glass is the temperature of the first inflection point of the DTA spectrum obtained by Differential Thermal Analysis (DTA).

The glass softening point Ts of the flat glass is preferably 700 ℃ or higher, more preferably 750 ℃ or higher, still more preferably 800 ℃ or higher. On the other hand, from the viewpoint of ease of processing, the glass softening point Ts of the plate-like glass is preferably 1500 ℃ or less, more preferably 1000 ℃ or less, and still more preferably 950 ℃ or less. The glass softening point Ts of the plate glass is the temperature of the fourth inflection point of the DTA spectrum.

The difference between the glass softening point Ts of the glass substrate and the glass transition point Tg of the plate-like glass is preferably within the above-described range, specifically, 800 ℃ or lower, more preferably 700 ℃ or lower, and even more preferably 600 ℃ or lower. In addition, from the viewpoint of suppressing an increase in carbon residue during firing and thereby inhibiting insulation properties, the glass softening point Ts of the glass ceramic is preferably 450 ℃ or higher, more preferably 460 ℃ or higher, and even more preferably 470 ℃ or higher. The glass softening point Ts of the glass substrate is the temperature of the fourth inflection point of the DTA spectrum of the glass monomer.

The glass transition point Tg of the glass substrate is preferably 740℃or lower, more preferably 500℃or lower, and further preferably 450℃or lower. Further, from the viewpoint of suppressing an increase in carbon residue during firing and thereby inhibiting insulation properties, the glass transition point Tg of the glass ceramic is preferably 380 ℃ or higher, more preferably 390 ℃ or higher, and still more preferably 400 ℃ or higher. The glass transition point Tg of the glass matrix is the temperature of the first inflection point of the DTA spectrum of the glass monomer.

The thermal expansion coefficient of the plate glass is a value equal to or higher than the thermal expansion coefficient of the glass ceramic. That is, the difference represented by (the thermal expansion coefficient of the plate-like glass-the thermal expansion coefficient of the glass ceramic) is 0/. Degree.C.or more. In addition, the difference is 20×10 ^－7 And/or lower. Thus, when the plate glass and the outer frame are directly bonded, the plate glass can be prevented from cracking.

The difference is 0/DEG C or more, more preferably 0.5X10 ^－7 At least one temperature/. Degree.C, more preferably 1X 10 ^－7 And/or higher. In addition, the difference is 20×10 ^－7 It is not higher than °c, more preferably 15×10 ^－7 Preferably 10X 10 or less at a temperature of/DEG C ^－7 And/or lower.

The difference between the coefficient of thermal expansion of the plate-like glass and the coefficient of thermal expansion of the glass ceramic is not particularly limited as long as it is within the above range, and is preferably 5×10 in view of the limitation of the selectivity of the glass ceramic ^－7 At least 30X 10, more preferably ^－7 Preferably 70X 10 or more at a temperature of not less than ^－7 And/or higher. The thermal expansion coefficient of the flat glass and the thermal expansion coefficient of the glass ceramic in the present specification are values measured from an average value of the ratio of elongation per 1 ℃ when the glass and the glass ceramic are heated in a range of 50 to 350 ℃.

The difference between the coefficient of thermal expansion of the glass ceramic and the coefficient of thermal expansion of the flat glass is not particularly limited as long as it is within the above range, and it is required to be close to the expansion of the substrate on which the cover glass with the outer frame is mounted, preferably 80×10 ^－7 Preferably 50X 10 or less at a temperature of/DEG C ^－7 Preferably 30X 10, at a temperature of not higher than °C ^－7 And/or lower.

From the viewpoint of lowering the glass softening point Ts, the glass ceramic preferably contains at least one of bismuth oxide and boron oxide in the glass composition of the glass matrix.

The content of bismuth oxide is preferably 50 mass% or more, more preferably 60 mass% or more, from the viewpoint of lowering the glass softening point Ts of the glass base body as compared with the glass transition point Tg of the flat glass. On the other hand, from the viewpoint of suppressing the decrease in weather resistance of the flat glass, the content of bismuth oxide is preferably 90 mass% or less, more preferably 80 mass% or less.

In the present specification, the content of the glass composition in the glass matrix is a value expressed by mass% based on the oxide with respect to the content of the component obtained by removing the filler component from the glass ceramic.

The content of boron oxide is preferably 3 mass% or more, more preferably 10 mass% or more, and even more preferably 30 mass% or more, from the viewpoint of lowering the glass softening point Ts of the glass base body as compared with the glass transition point Tg of the flat glass. On the other hand, from the viewpoint of suppressing the decrease in weather resistance of the flat glass, the content of boron oxide is preferably 60 mass% or less, more preferably 55 mass% or less, and further preferably 50 mass% or less.

When bismuth oxide and boron oxide are contained together, the content of bismuth oxide is preferably more than the content of boron oxide, more preferably the content of boron oxide is 1/5 or less of the content of bismuth oxide, and further preferably the total content of bismuth oxide and boron oxide is 90 mass% or less, from the viewpoint of suppressing the decrease in weather resistance of the flat glass.

The total content of bismuth oxide and boron oxide is preferably 3 mass% or more, more preferably 4 mass% or more, and even more preferably 5 mass% or more, from the viewpoint of lowering the glass softening point Ts of the glass base body as compared with the glass transition point Tg of the flat glass. The total content is preferably 16 mass% or less, more preferably 12 mass% or less, and even more preferably 10 mass% or less, from the viewpoint of suppressing the decrease in weather resistance of the flat glass.

As described above, the glass substrate containing at least one of bismuth oxide and boron oxide is generally referred to as bismuth oxide glass or borosilicate glass.

As bismuth oxide-based glass, bi is used in addition to ₂ O ₃ In addition to B may be contained ₂ O ₃ 、CeO ₂ 、SiO ₂ 、RO、R’ ₂ O、R” ₂ O ₃ 、R”’O ₂ Etc.

R is at least one selected from Zn, ba, sr, mg, ca, fe, mn, cr and Cu. R' is at least one selected from Li, na, K, cs and Cu. R' means at least one selected from Al, fe and La. R' "is at least one selected from the group consisting of Zr, ti and Sn.

In addition, when R' is Al, al is ₂ O ₃ Clearly distinguished from alumina, which is a filler component constituting the glass ceramic. That is, al to be a glass composition ₂ O ₃ The content is removed from the content of the alumina-containing crystal powder as a filler component.

More specifically, for example, a material containing 27 to 85 mass% of Bi can be suitably used ₂ O ₃ And 5 to 30 mass% of B ₂ O ₃ Is a glass of (a). The glass may further contain 0 to 10 mass% of CeO ₂ 0 to 20 mass% of SiO ₂ 0 to 55 mass% of RO and 0 to 10 mass% of R' ₂ O, 0 to 20 mass% of R' ₂ O ₃ 0 to 30 mass% of R' O ₂ 。

As borosilicate glass, in addition to SiO ₂ And B ₂ O ₃ In addition to CeO may be contained ₂ 、RO、R’ ₂ O、R” ₂ O ₃ 、R”’O ₂ Etc., preferably contains ZnO, K ₂ O、Na ₂ O。

More specifically, for example, a material containing 23 to 35 mass% of SiO can be suitably used ₂ 40 to 55 mass% of B ₂ O ₃ 10 to 20 mass% of ZnO and 3 to 15 mass% of K in total ₂ O and Na ₂ O glass.

The following is a case of bismuth oxide (Bi ₂ O ₃ ) And boron oxide (B) ₂ O ₃ ) The components other than the above are described.

SiO ₂ Is a component constituting glass. On the other hand, when the amount is excessively large, the glass softening point Ts may be excessively high.

CeO ₂ When bismuth oxide is contained in the glass powder to stabilize the color tone of the glass powder after melting and vitrifying the glass raw material, the bismuth oxide is preferably contained together. On the other hand, if the glass powder is excessively added, the glass powder tends to be easily crystallized, and thus it is difficult to obtain a stable glass powder.

The RO containing CaO represents a component effective for stabilizing glass and inhibiting crystallization. On the other hand, when the amount is excessively large, the glass softening point Ts may be excessively high.

Comprises K ₂ O and Na ₂ R 'of O' ₂ The component represented by O is a component that lowers the glass softening point Ts. The smaller the atomic number, the greater the effect. However, if the content of the element having a smaller atomic number is increased, the insulation properties of the glass may be lowered, and the reliability may be impaired.

Comprises Al ₂ O ₃ R' of (2) " ₂ O ₃ The components shown are effective for stabilizing glass, and have an effect of suppressing crystallization and an improved chemical durability of glass. On the other hand, when the amount is excessively large, the glass softening point Ts may be excessively high.

R”’O ₂ The components shown are those that supply oxygen during bonding. On the other hand, when excessively added, there is a possibility that foaming may occur at the time of joining.

The filler component in the glass ceramic preferably contains a filler selected from the group consisting of alumina, zirconia, titania, magnesia, silica, zirconium phosphate, and beta-eucryptite (LiAlSiO) ₄ ) And at least 1 of them, more preferably contains a crystalline powder comprising alumina. The crystal powder more preferably contains silica in addition to alumina.

The alumina may be an α -alumina type, a γ -alumina type, a δ -alumina type, a θ -alumina type, or the like depending on the kind of the crystal phase, and the crystal phase is preferably an α -alumina type having a corundum type structure.

The content of the crystal powder as the filler component in the glass ceramic, particularly the crystal powder containing alumina, is preferably 5 mass% or more, more preferably 10 mass% or more, from the viewpoint of preventing cracking of the plate-like glass. In addition, from the viewpoint of obtaining good adhesion to the plate-like glass, the content of the crystal powder is preferably 40 mass% or less, more preferably 35 mass% or less, still more preferably 30 mass% or less, and still more preferably 25 mass% or less. The above content also varies depending on the specific gravity of the filler component. For example, when the specific gravity of the filler is 2.6 or less, the content of the crystal powder containing alumina is preferably 25 mass% or less from the viewpoint of obtaining good sinterability. The content of the alumina-containing crystal powder as the filler component in the glass ceramic is the same as the content of the inorganic component in the glass ceramic.

The shape of the crystal powder is not particularly limited, and is spherical, flat, scaly, fibrous, or the like.

The size of the crystal powder is not particularly limited either, and for example, 50% particle diameter (D ₅₀ ) Preferably 0.5 μm or more, more preferably 1 μm or more, and further preferably 4 μm or less, more preferably 3 μm or less. The 50% particle diameter is a value measured by a laser diffraction/scattering particle size distribution measuring apparatus.

The flat glass is not particularly limited as long as the coefficient of thermal expansion and the glass transition point Tg satisfy the above relationship with the coefficient of thermal expansion of the glass ceramic and the glass softening point Ts of the glass substrate.

For example, the plate glass preferably has a transmittance of 90% or more at a wavelength of 250 to 1500 nm.

Specifically, soda lime glass, borosilicate glass, aluminosilicate glass, silica glass, or the like can be used as the plate glass. Borosilicate glass is preferred in terms of ease of processing. In addition, silica glass is preferable in terms of durability and permeability.

The cover glass with outer frame 10 of the present embodiment may be provided with a metal film 3, a conductive film 4, and a metal conductor 5 indicated by metal films 3a and 3b, in addition to the flat glass 1 and the outer frame 2, as shown in fig. 1. The respective components will be described in order below.

The thickness of the plate-like glass 1 is not particularly limited, but is preferably 200 μm or more, more preferably 300 μm or more, and still more preferably 500 μm or more from the viewpoint of durability. On the other hand, the thickness of the flat glass is preferably 1.5mm or less, more preferably 1mm or less, and still more preferably 0.75mm or less from the viewpoints of permeability and weight.

The height of the outer frame 2 made of glass ceramic is preferably 350 μm or more, more preferably 400 μm or more, and even more preferably 500 μm or more, from the viewpoint of preventing the cover glass from being damaged by light energy from the light source. On the other hand, from the viewpoint of the demand for the reduction in height of the apparatus, the height of the outer frame is preferably 1.5mm or less, more preferably 1.35mm or less, and still more preferably 1mm or less.

The outer frame 2 may be formed by forming the metal film 3 on a surface of the surface opposite to the surface to which the flat glass 1 is bonded, and is preferably formed in view of air tightness when bonding the cover glass with the outer frame to the substrate. The substrate and the cover glass with the outer frame can be hermetically sealed by adhesion using a metal solder due to the presence of the metal film.

From the viewpoint of adhesion when using a metal solder, the metal film 3 preferably has a metal film 3b containing 1 or more selected from Au, ag, cu, and au—sn alloy on its outermost surface, and more preferably has an Au film. The base of the film may be a film (not shown) such as a Ni film or a Ti film.

When the outer frame 2 includes a metal conductor described later, the metal film 3 preferably includes a metal film 3a using the same metal as the metal conductor, and the metal film 3b formed on the surface thereof.

In view of the use of the cover glass with the outer frame, the outer frame is preferably disposed perpendicularly to the plate-like glass. The plate glass being perpendicular to the outer frame means that the angle formed by the plate glass and the outer side surface of the outer frame is perpendicular. The vertical direction need not be exactly 90 °, but may be substantially vertical at 90±5°.

The cover glass with the outer frame is preferably provided with a system capable of detecting breakage of the cover glass according to the application. As an example of the system, the flat glass 1 preferably includes the conductive film 4 in at least a partial region of the main surface of the side to which the outer frame 2 is bonded. In addition, it is preferable that a metal conductor 5 penetrating the glass ceramic is formed inside the outer frame 2, and the conductive film 4 and the metal conductor 5 are electrically connected.

The conductive film 4 may be a conventionally known conductive film, and is preferably a transparent conductive film from the viewpoint of light transmittance, and examples thereof include an ITO (Indium Tin Oxide) film and SnO ₂ Films, znO films, and the like. Among them, an ITO film is preferable in terms of durability and resistance.

The thickness of the conductive film is not particularly limited, but is preferably 0.05 μm or more, more preferably 0.1 μm or more, and still more preferably 0.2 μm or more, in order to secure stable conductivity. In order to maintain the permeability, the thickness of the conductive film is preferably 1 μm or less, more preferably 0.8 μm or less, and still more preferably 0.7 μm or less.

The conductive film may be formed on at least a part of the main surface of the plate-like glass, and is preferably formed at least in the effective region, that is, the region where light from the light source is irradiated, and more preferably formed on the entire main surface of the plate-like glass, in order to detect breakage of the cover glass.

In the case where a film or layer other than the conductive film is formed on the main surface of the flat glass, it is preferable that the conductive film is formed on the outermost surface of the other film or layer, that is, on the side of the substrate provided with the light source.

The metal conductor 5 is also sometimes referred to as a via hole, and refers to a conductor that electrically connects an upper layer wiring and a lower layer wiring. In the present embodiment, the metal conductor 5 is electrically connected to the conductive film 4, and connects the conductive film 4 to a detector for detecting breakage of the cover glass.

The metal conductor may be applied to a conventionally known metal conductor by a conventionally known method. For example, before or after firing the glass ceramic constituting the outer frame, holes penetrating the inside of the outer frame are provided, and metal conductors are laid therein.

The metal conductor may be any metal having conductivity, and is preferably 1 or more selected from Ag, au, and Cu, more preferably Ag, in view of ease of production. The ease of manufacture means that the glass ceramics to be the outer frame can be sintered together when they are sintered by firing.

The shape of the metal conductor is not particularly limited, and a metal wire is preferable from the viewpoint of easy penetration into the outer frame. The diameter of the through hole as the diameter of the metal wire is more preferably 0.2mm or less, and still more preferably 0.1mm or less, from the viewpoint of preventing the glass ceramic as the outer frame from cracking due to the large irregularities of the metal conductor during firing. The lower limit of the diameter of the through hole is not particularly limited, but is preferably 0.05mm or more from the viewpoint of preventing breakage of the metal conductor.

As shown in fig. 2, the cover glass with outer frame 10 of the present embodiment may further include a light diffusion layer 6, an antireflection film 7, and the like.

The light diffusion layer 6 is preferably formed on at least one main surface of the plate glass 1, and is preferably formed on at least the main surface on the side of the substrate provided with the light source.

The light diffusion layer may be made of an inorganic material, and is preferably made of an inorganic material from the viewpoint of preventing the light diffusion layer from disappearing when the outer frame is fired, and it is more preferable to directly process the flat glass from the viewpoint of preventing the loss due to the interface reflection. Further preferably, the lens is provided with a plurality of concave aspherical lenses, for example, by direct processing, and further preferably, the aspherical lenses are disposed without any gap in at least an effective region on the main surface of the plate-like glass.

The maximum size of the aspherical lens is not particularly limited, and is usually 250 μm or less, and the lower limit is usually 20 μm or more.

The spread angle of the aspherical lens, which is the spread angle of the outgoing light when parallel light is incident from the lens-processed surface facing the effective area, is preferably 30 ° or more in terms of the whole angle. The upper limit of the diffusion angle is usually 85 ° or less in terms of the full angle.

The antireflection film 7 is preferably formed on at least one main surface of the flat glass 1, more preferably at least on the main surface on the side of the substrate provided with the light source, and even more preferably on both main surfaces.

When the cover glass with the outer frame includes the light diffusion layer formed by direct processing, the antireflection film is preferably formed on the outer side of the light diffusion layer.

The antireflection film is not particularly limited as long as it has at least an antireflection function of reducing the reflectance of light of a design wavelength. From the viewpoint of preventing the outer frame from disappearing when the outer frame is calcined, the antireflection film is preferably a film made of an inorganic material, for example, a film having a single-layer structure, or a film made of SiO ₂ And Ta ₂ O ₅ And a multilayer film such as a dielectric multilayer film formed by laminating 2 or more kinds of dielectrics having different refractive indexes.

The sheet glass may have a layer, a film, or the like having a certain function in addition to the above-described configuration within a range that does not impair the effects of the present invention.

When the plate-like glass includes a layer or a film made of an inorganic material such as a light diffusion layer, an antireflection film, or a conductive film, and these layers or films are formed in a bonding region with the outer frame, the plate-like glass and the outer frame are bonded via the layers or films. In this case, it was also determined that the layer, the film and the plate glass were integrated, and the plate glass was directly bonded to the outer frame.

The cover glass 10 with the outer frame may be obtained by cutting a part of the outer frame 2 to take out the metal conductor 5. For example, as shown in fig. 3, the diagonal portion may be chamfered so as to be a straight line passing through the flat glass 1 and the outer frame 2, and the metal conductor 5 may be taken out from the position indicated by the arrow. The chamfering method is not limited, and conventionally known methods may be used, and examples thereof include a machining method called oblique grinding, polishing, and the like.

In order to remove the metal conductor 5 without being limited by space, it is advantageous to form the cover glass 10 with an outer frame into a shape as shown in fig. 3.

< method for producing cover glass with outer frame >

An embodiment of a method for manufacturing cover glass 10 with an outer frame will be described.

The method for producing the glass ceramic to be the outer frame 2 in the cover glass with the outer frame is not particularly limited, and is obtained by molding and firing a mixture of glass powder and ceramic powder, for example. Specifically, the above mixture is molded into a sheet shape called a green sheet, and calcined.

An example of a method for producing the green sheet is shown below.

First, the raw materials are mixed so as to have a desired glass composition, and the raw material mixture obtained by this is melted, cooled, and pulverized to obtain glass powder. The glass composition of the glass ceramic was determined by firing the glass powder obtained by grinding into a glass matrix.

The melting temperature of the raw material mixture is preferably, for example, 1200 to 1600 ℃ or higher, and the melting time is preferably, for example, 30 to 60 minutes.

The pulverization may be performed by a dry pulverization method or a wet pulverization method. In the case of the wet pulverization method, water, ethanol, or the like may be used as a solvent.

For example, a roll mill, a ball mill, a jet mill, or the like can be used for the pulverization.

The size of the glass powder was 50% in particle diameter (D from the viewpoint of preventing aggregation of the glass powder and making handling difficult and preventing the time required for powdering from becoming long ₅₀ ) Preferably 0.5 μm or more, more preferably 1 μm or more. In addition, from the viewpoint of preventing the rise of the glass softening point Ts and the insufficient sintering, the particle diameter of 50% (D ₅₀ ) Preferably 4 μm or less, more preferably 3 μm or less.

The maximum particle diameter of the glass powder is preferably 20 μm or less, more preferably 10 μm or less, from the viewpoint of obtaining good sinterability and preventing a decrease in reflectance due to the undissolved components remaining in the sintered body.

The particle size can be adjusted by classifying the pulverized material as needed.

Next, the glass powder is mixed with a filler component to obtain a glass ceramic composition.

The filler component may be any conventionally known filler component, and preferably a crystalline powder containing alumina. More specifically, alumina powder, cordierite powder, zirconium phosphate powder are preferable.

The glass ceramic composition is mixed with an organic solvent, a plasticizer, a binder, a dispersant, and the like as necessary to prepare a slurry or paste. The materials to be blended may be conventionally known materials.

Examples of the organic solvent include alcohols, ketones, and aromatic hydrocarbons. More specifically, toluene, methyl ethyl ketone, methanol, 2-butanol, xylene, etc. may be used, and 1 kind of them may be used, or 2 or more kinds may be mixed.

Examples of the plasticizer include adipic acid-based plasticizers and phthalic acid-based plasticizers. More specifically, bis (2-ethylhexyl) adipate, dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate, and the like may be used.

The binder may be a thermally decomposable resin or the like. More specifically, acrylic resin, polyvinyl butyral, or the like can be used.

Examples of the dispersant include surfactant-type dispersants. More specifically, DISPERBYK180 (trade name, manufactured by BYK-Chemie Co.) or the like can be used.

The obtained slurry or paste is coated on a film and dried to obtain a green sheet. The thickness of the green sheet is not particularly limited, and may be adjusted according to the thickness, slurry concentration, and the like at the time of coating.

The obtained green sheets are properly stacked according to the desired outer frame height. Then, the inside is punched out by a tapping machine, thereby forming an outer frame shape. In this case, the metal conductors may be formed together with through holes.

The glass ceramic may be a molded product molded by a mold or the like, not a green sheet, but a green sheet is preferable in view of easy wiring passing through each layer.

The blank may be manufactured one by one in accordance with a desired outer frame shape, or a large blank may be manufactured and punched out at a plurality of positions by a punching machine, whereby an outer frame as a multi-piece connection substrate formed by a plurality of connection pieces may be manufactured. At this time, the green sheet and the flat glass are superimposed and hot-pressed, and the superimposed body obtained as described above is calcined, whereby a multi-piece cover glass with an outer frame, in which the green sheet is connected to a glass ceramic, is obtained. The cover glass with the outer frame is divided into a plurality of pieces of cover glass with the outer frame, which are connected to each other, to obtain individual cover glass with the outer frame. Alternatively, the green sheet laminate may be calcined alone to prepare a glass ceramic, and then superimposed on a flat glass and calcined again to be directly bonded.

The shape of the outer frame is determined by the shape of the blank. That is, the shape of the inner side of the outer frame is derived from the shape when the green sheet is punched. The shape of the outer side of the outer frame is derived from the outer shape of the blank. When the multi-piece connection substrate is divided, the shape of the divided substrate after calcination is the outer shape of the outer frame.

A metal film is formed on one surface of the blank sheet having the outer frame shape as needed. The metal film may be formed by applying a metal paste by screen printing, for example.

In addition, when the metal conductor is provided, the metal conductor may be formed by filling a metal paste into a preformed through hole by, for example, screen printing.

The metal film and the metal conductor may be formed by a sputtering method, a vapor deposition method, or the like, in addition to the screen printing method.

Next, a flat glass is superimposed on the surface of the blank opposite to the surface on which the metal film is formed, and the flat glass is integrated by hot pressing, to obtain a cover glass with an unsintered outer frame.

When forming a layer or film such as a light diffusion layer, an antireflection film, or a conductive film on the main surface of the plate glass, the layer or film may be formed before the plate glass is laminated on the green sheet, or may be formed after the cover glass with the outer frame is obtained. However, in the case of forming a conductive film and conducting it to a metal conductor, it is preferable to form the conductive film in advance before the flat glass is stacked on the green sheet.

The conditions are not particularly limited as long as the raw sheet and the flat glass are integrated, as long as the raw sheet and the flat glass 1 are directly bonded by hot pressing after being superimposed.

The temperature at the time of crimping is preferably 60 to 65 ℃. The pressure at the time of press-bonding is preferably 12400 to 14000Pa, for example. The time for the press-bonding is preferably, for example, 5 to 10 minutes.

The cover glass with the outer frame 10 with the outer frame is obtained by directly bonding the glass ceramic as the outer frame 2 with the flat glass 1 by degreasing the cover glass with the unsintered outer frame as needed and firing the glass, thereby forming the green sheet into the glass ceramic in which the filler component is dispersed in the glass matrix.

In consideration of the adhesiveness when using a metal solder in bonding with a substrate, the metal film 3 may be formed on the main surface of the outer frame on the opposite side to the side to which the plate-like glass is bonded. In this case, in addition to the metal film 3b located on the outermost surface to be bonded to the substrate, a film serving as a base of the metal film 3b may be formed, and a metal film 3a using the same metal as the metal conductor 5 may be formed between the film serving as a base or the metal film 3b and the outer frame.

The metal film 3 may be formed before calcination or after calcination, and is preferably formed before calcination in view of workability.

When the cover glass with the unsintered outer frame is a multi-piece connection substrate, the cover glass with the outer frame is obtained by cutting between adjacent holes by a cutter after firing.

Degreasing is carried out as needed, and is preferably 400 to 500 ℃. The degreasing time is preferably, for example, 1 to 10 hours.

The temperature at the time of firing is preferably a temperature equal to or higher than the glass softening point Ts of the glass matrix in the glass ceramic and lower than the glass transition point Tg of the plate-like glass. Thereby, the surface of the flat glass is prevented from being damaged by heat.

The specific firing temperature also varies depending on the glass composition of the glass ceramic, and is preferably 500 ℃ or higher, more preferably 520 ℃ or higher, and even more preferably 550 ℃ or higher, from the viewpoint of obtaining sufficient sinterability. In addition, from the viewpoint of preventing metal such as a metal film and a metal conductor from melting, the calcination temperature is preferably 900 ℃ or less, more preferably 750 ℃ or less, and still more preferably 600 ℃ or less.

The calcination time is preferably 10 minutes or more, more preferably 15 minutes or more, and even more preferably 25 minutes or more, from the viewpoint of obtaining sufficient sinterability. In addition, from the viewpoint of productivity, the calcination time is preferably 60 minutes or less, more preferably 55 minutes or less, and further preferably 50 minutes or less.

The flat glass 1 may be produced by a conventionally known method, or may be a commercially available product.

For example, glass raw materials are prepared so as to obtain glass having a desired composition, and the glass raw materials are heated and melted. Then, the molten glass is homogenized by bubbling, stirring, adding a fining agent, etc., and formed into a glass plate having a predetermined thickness by a known forming method, and then slowly cooled. The molten glass may be shaped into a flat plate by homogenizing the molten glass, shaping the molten glass into a block, and then cutting the block after slow cooling.

Examples of the method for forming the flat glass include a float method, a press method, a fusion method, and a downdraw method. In particular, the downdraw method is preferable from the viewpoint of controlling the glass thickness.

The metal film 3 is formed on the surface of the outer frame facing the surface to which the plate glass is bonded. The metal film 3a using the same metal as the metal conductor can be formed by a conventionally known method. For example, the conductive paste may be formed by adding a Vehicle (Vehicle) such as ethylcellulose, a solvent if necessary, or the like to a metal powder to prepare a paste, and applying the paste by a screen printing method.

The metal coating 3b located on the outermost surface and the coating to be the base thereof may be formed by a conventionally known method, and may be formed by, for example, a plating process. Alternatively, the plating may be performed by electroless plating. Electroplating is preferred from the viewpoint of cost.

The substrate and the cover glass with the outer frame can be hermetically sealed by adhesion using a metal solder due to the presence of the metal coating 3 b.

The conductive film 4 may be formed on the main surface of the plate glass by a conventionally known method. For example, when the conductive film is an ITO film, it is preferably formed by a sputtering method.

When the light diffusion layer 6 and the antireflection film 7 are formed on the main surface of the plate glass, the conductive film is preferably formed on the outermost surface thereof, that is, on the side closest to the substrate.

The antireflection film 7 may be formed on at least one main surface of the plate-like glass by a known film forming method such as sputtering or vapor deposition. That is, the high refractive index layer and the low refractive index layer constituting the antireflection film are sequentially formed on the main surface of the plate glass in the order of lamination.

Examples of the sputtering method include magnetron sputtering, pulse sputtering, AC sputtering, and digital sputtering. Examples of the vapor deposition method include a vacuum vapor deposition method, an ion beam assisted method, and an ion plating method.

The antireflection film may be formed on at least one main surface of the plate-like glass, and is preferably formed on at least the main surface on the side where the substrate is located. When the light diffusion layer 6 is formed on the main surface of the plate glass, an antireflection film is preferably formed on the surface of the light diffusion layer.

The cover glass with an outer frame according to the present embodiment is excellent in air tightness and cost, and therefore, is excellent in productivity. In addition, as a bonding method with the substrate, a metal material may be used in addition to bonding via a metal film.

Since the light source has such characteristics, the light source is suitable for use as, for example, a backlight for a liquid crystal display or the like, a light emitting portion in an operation button of a small information terminal, a deep ultraviolet LED for lighting or decoration for automobiles, sterilization, a laser portion for a 3D distance measuring sensor, and other light sources.

Examples

The present invention will be specifically described with reference to the following examples, but the present invention is not limited thereto. Examples 1 to 4 are examples, and examples 5 to 8 are comparative examples.

[ Flat glass ]

As the plate glass 1, a borosilicate glass plate (D263 (registered trademark) Teco manufactured by SCHOTT Co., ltd.) of 50 mm. Times.50 mm. Times.1.1 mm was used.

The light diffusion layer 6 is formed by directly processing a plurality of concave aspherical lenses over the entire area on one principal surface of the plate glass 1. The maximum size of the aspherical lens is 200 μm, and the spread angle is 50 ° in terms of full angle.

Next, the antireflection film 7 is formed on the entire region on both principal surfaces of the flat glass 1 by sputtering. The antireflection film is formed with Ta on both sides in sequence ₂ O ₅ As a high refractive index layer and SiO ₂ As a film with a thickness of 0.4 μm of the low refractive index layer.

An ITO film having a thickness of 0.3 μm was formed as the conductive film 4 on the entire surface of the plate glass 1 on the side where the light diffusion layer 6 was formed by sputtering.

Thus, a flat glass having a light diffusion layer, an antireflection film, and a conductive film was obtained.

Example 1

Expressed as a percentage of the oxide basis to become Bi ₂ O ₃ :73 mass%, znO:18 mass%, B ₂ O ₃ :5 mass% and SiO ₂ :4 mass% of glass raw materials were mixed together to prepare a raw material mixture. The raw material mixture was put into a platinum crucible and melted at 1600 ℃ for 60 minutes, and then the molten glass was poured out and cooled. The glass was placed in a container together with ethanol as a solvent, and pulverized by an alumina ball mill for 40 hours to obtain glass powder (glass a). The 50% particle size of the obtained glass powder was 0.6. Mu.m.

A glass ceramic composition was prepared by blending and mixing the glass powder obtained to be 80% by mass and cordierite powder (trade name: SS-600, manufactured by MARUSAGE Co., ltd.) to be 20% by mass. A slurry was prepared by mixing 1kg of a glass ceramic composition with 0.35kg of a solvent mixed with toluene, methyl ethyl ketone, and methanol, 2-butanol=3:3:1:1 (mass ratio), 0.060kg of bis (2-ethylhexyl) adipate as a plasticizer, 0.447kg of an acrylic resin as a binder, and 0.015kg of a dispersant (trade name: DISPERBYK180, manufactured by BYK-Chemie Co., ltd.) as an organic solvent.

The slurry was coated on a polyethylene terephthalate (PET) film by a doctor blade method, and dried, thereby manufacturing a green sheet. The thickness of each green sheet was 200. Mu.m.

6 green sheets were stacked, and a hole having a diameter of 170 μm was formed in each of the 6 green sheets by using a hole punching machine to punch a substantially rectangular hole having a diameter of 2.57mm×1.75 mm.

A silver paste (trade name: US-202A, manufactured by Daiko chemical industries Co., ltd.) was applied to one surface of the green sheet by screen printing, and the same silver paste was filled into the through holes to form an uncalcined metal film 3a and a metal conductor 5.

Next, a flat glass having a light diffusion layer, an antireflection film, and a conductive film is superimposed on the surface of the green sheet opposite to the side on which the metal film 3a is formed. At this time, the flat glass is overlapped in such a direction that the main surface of the conductive film side is bonded to the green sheet.

The resultant was subjected to hot pressing at 65℃and 14000Pa to obtain a cover glass with an unsintered outer frame. Then, the mixture was kept at 450℃for 2 hours to defat, and further kept at 520℃for 30 minutes to calcine. The outer frame is formed into a sintered glass ceramic by firing, and the outer frame is directly bonded to the flat glass. Then, a nickel film is formed as a base on the surface of the metal film 3a of the outer frame by a plating process, and further, a gold film is formed as a metal film 3b by a plating process. Thus, a cover glass with an outer frame was obtained. The height of the outer frame is 870 mu m.

Example 2

The glass raw material in the blank sheet is expressed as Bi in terms of percentage based on oxide ₂ O ₃ :72 mass%, B ₂ O ₃ :10 mass%, znO:9 mass%, baO:6 mass% and SiO ₂ : a cover glass with an outer frame was obtained in the same manner as in example 1, except that 3 mass% of the glass powder (glass B) was prepared by blending and mixing.

Example 3, example 5, example 7

Cover glass with an outer frame was obtained in the same manner as in example 1 except that the cordierite powder (trade name: SS-600, manufactured by MARUSAZE Co.) in the glass ceramic composition was changed to the content described in the column "crystal powder" of Table 1.

Example 4, example 6 and example 8

Cover glass with an outer frame was obtained in the same manner as in example 2 except that the cordierite powder (trade name: SS-600, manufactured by MARUSAZE Co.) in the glass ceramic composition was changed to the content described in the column "crystal powder" of Table 1.

[ evaluation ]

The glass transition point Tg and the glass softening point Ts of the glass matrix in the plate-like glass and the glass ceramic are determined from the first inflection point and the fourth inflection point of the spectrogram measured under the condition of 5 ℃/min based on Differential Thermal Analysis (DTA). The results are shown in table 1.

The thermal expansion coefficients of the plate-like glass and the glass ceramic are determined from an average value of the ratio of elongation per 1 ℃ when measured under the condition of 5 ℃ per minute in the range of 50 ℃ to 350 ℃ based on thermo-mechanical analysis (TMA). The results are shown in table 1. In the table, "-" indicates that measurement was not performed.

When a cover glass with an outer frame is obtained by directly bonding a flat glass to an outer frame by degreasing and firing the cover glass with an unsintered outer frame, whether or not cracking occurs in the flat glass is checked by a microscope. The results are shown in table 1. In table 1, the case where the outer frame was not sintered to a glass ceramic even when the cover glass with the outer frame was calcined, is referred to as "(unsintered)".

TABLE 1

From the above results, it can be confirmed that: by setting the thermal expansion coefficient of the flat glass to a value equal to or higher than the thermal expansion coefficient of the glass ceramic and reducing the difference between them, it is possible to directly join the two without cracking the flat glass. Thus, the cover glass with the outer frame can be provided, which maintains airtight sealing and reduces damage and cracks of the cover glass. Further, by changing the number of layers of the green sheets used as the outer frame material, the height of the outer frame can be made to have a desired value.

The present application has been described in detail with reference to specific embodiments, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. The present application is based on japanese patent application (japanese patent application 2020-213972) filed on 12 months and 23 days in 2020, the contents of which are incorporated herein by reference.

Symbol description

1 plate glass

2 outer frame

3 Metal film

3a metal coating

3b Metal coating

4 conductive film

5 Metal conductor

6 light diffusion layer

7 antireflection film

10 cover glass with outer frame

Claims

1. A cover glass with an outer frame, wherein the outer frame is arranged on one main surface of a plate-shaped glass,

the outer frame is composed of glass ceramic in which filler components are dispersed in a glass matrix,

the glass-softening point of the glass matrix contained in the glass ceramic is lower than the glass transition point of the plate-like glass,

the thermal expansion coefficient of the plate-like glass is equal to or higher than that of the glass ceramic, and the difference is 0 to 20X 10 ^－7 /℃，

The flat glass is directly bonded to the glass ceramic.

2. The cover glass with an outer frame according to claim 1, wherein the glass base contains at least one of bismuth oxide and boron oxide.

3. The cover glass with an outer frame according to claim 1 or 2, wherein the glass ceramic contains 5 to 40 mass% of crystal powder containing alumina as the filler component.

4. The cover glass with an outer frame according to any one of claims 1 to 3, wherein a metal film is formed on a surface of the outer frame opposite to a surface to which the flat glass is bonded.

5. The cover glass with an outer frame according to any one of claims 1 to 4, wherein the outer frame is provided perpendicularly to the flat glass.

6. The cover glass with an outer frame according to any one of claims 1 to 5, wherein the height of the outer frame is 350 μm to 1.5mm.

7. The cover glass with an outer frame according to any one of claims 1 to 6, wherein the flat glass has a conductive film in at least a part of a main surface of one side where the outer frame is joined,

the metal conductor penetrating the outer frame is formed inside the outer frame,

the metal conductor is disposed perpendicularly to the plate-like glass,

the conductive film is in electrical communication with the metal conductor.

8. The cover glass with an outer frame according to any one of claims 1 to 7, wherein the flat glass has an antireflection film on at least one main surface.

9. The cover glass with an outer frame according to any one of claims 1 to 8, wherein the plate-like glass has a light diffusion layer on at least one main surface.