WO2022138518A1

WO2022138518A1 - Cover glass equipped with outer frame

Info

Publication number: WO2022138518A1
Application number: PCT/JP2021/046890
Authority: WO
Inventors: まりな熊谷
Original assignee: Ａｇｃ株式会社
Priority date: 2020-12-23
Filing date: 2021-12-17
Publication date: 2022-06-30
Also published as: CN116670082A; JPWO2022138518A1; TW202226465A

Abstract

The present invention relates to cover glass equipped with an outer frame, wherein: the outer frame is composed of a glass ceramic in which a filler component is 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 flat glass; the thermal expansion coefficient of the flat glass is equal to or greater than the thermal expansion coefficient of the glass ceramic, and the difference therebetween is 0-20 × 10-7/°C; and the flat glass and the glass ceramic are directly joined to each other.

Description

Cover glass with outer frame

The present invention relates to a cover glass with an outer frame.

Devices using light emitting diodes (LEDs: Light Mission Diodes) are used in a wide range of applications such as backlights for mobile phones and large LCD televisions, and lighting applications.
For example, in the case of a light emitting device using a light emitting diode (visible light LED) that emits visible light, an LED chip is placed on a flat plate-shaped substrate such as aluminum nitride, and a resin-based member is used. A sealing configuration is often used.

On the other hand, a light emitting device using a light emitting diode (UV-LED), a laser diode (LD), a vertical cavity type surface light emitting laser (VCSEL) or the like that emits ultraviolet light requires airtight sealing. Also, VCSELs require a diffuser.
Therefore, these light emitting devices are required to have a shape in which an outer frame is attached to the cover glass. Although the outer frame can be provided on a substrate such as aluminum nitride, it is realistic to provide the outer frame on the cover glass from the viewpoint of cost.

In manufacturing a cover glass with an outer frame, the simplest method is to prepare a cover glass and a glass for the outer frame, respectively, and bond them with a resin-based member. However, it cannot be hermetically sealed by adhesion using a resin-based member that is an organic substance.
In order to obtain the airtight sealability, a method of forming the outer frame portion by directly wet-etching the glass can be mentioned. However, the verticality between the flat plate-shaped portion and the outer frame portion cannot be obtained. Therefore, in order to obtain the airtight sealing property while maintaining the verticality, direct bonding such as diffusion bonding or room temperature bonding between the flat glass and the glass serving as the outer frame can be mentioned. On the other hand, direct joining is very costly.

On the other hand, techniques for providing an outer frame on a glass substrate have been studied and proposed from various angles.
For example, in the synthetic quartz glass cavity disclosed in Patent Document 1, a plurality of through holes are formed in the raw material synthetic quartz glass substrate by sandblasting. Such a synthetic quartz glass cavity can be obtained by laminating this raw material synthetic quartz glass substrate and another raw material synthetic quartz glass substrate and adhering them at 1000 to 1200 ° C.
Patent Document 2 discloses antireflection glass with a frame using borosilicate glass as a flat plate-shaped member and a silicon substrate as a frame-shaped member. Such a framed antireflection glass can be obtained by subjecting a silicon substrate to reactive ion etching to form through holes, superimposing a frame-shaped member on a flat plate-shaped member, and joining the two by anode bonding.

Patent Document 3 discloses a glass encapsulant in which a glass plate and a glass piece are sandwiched between a base mold and a facing mold and heat-pressed to join the glass plate and the glass piece by welding.
Patent Document 4 discloses an airtight container using a bonding material formed by screen-printing a paste such as glass frit having a softening point lower than that of the glass substrate on the glass substrate as a frame member.
In Patent Document 5, the mold is filled with a paste made of a heat-extinguishing curable resin composition containing glass powder, or a sheet made of a heat-extinguishing curable composition containing glass powder is pressure-bonded to the mold. A method of obtaining a glass substrate having a partition wall by heating the glass substrate is disclosed.

Japanese Patent Application Laid-Open No. 2020-21937 Japanese Patent No. 5646981 Gazette Japanese Patent Application Laid-Open No. 2013-2225222 Japanese Patent Application Laid-Open No. 2011-233479 Japanese Patent Application Laid-Open No. 2005-243454

However, if heat is applied at a temperature exceeding the glass softening point of the glass material used as in the methods described in

Patent Documents

1 and 3, the surface of the glass will be damaged and reliability is a concern. If the coefficient of thermal expansion of the flat plate-shaped member and the frame-shaped member are different as in the method described in Patent Document 2, the glass of the flat plate-shaped member may be cracked. In addition, the cost of anodic bonding is high. When the paste is applied as in the method described in Patent Document 4, there is a concern that the sealing property may be deteriorated due to uneven coating or uneven film thickness. In the method described in Patent Document 5, the height of the partition wall, which is the outer frame, is limited to about 150 μm, and the height is limited.

Therefore, an object of the present invention is to provide a cover glass with an outer frame which can realize a height of an outer frame of a certain level or higher while maintaining airtight sealing property and reduces damage and cracks on the surface of the cover glass. do.

As a result of diligent studies by the present inventor, it was found that the above problems can be solved by using specific glass ceramics for the outer frame, and the present invention has been completed.

That is, the present invention and one aspect thereof relate to the following [1] to [9].
[1] A cover glass with an outer frame having an outer frame provided on one main surface of flat glass, and the outer frame is made of glass ceramics in which a filler component is dispersed in a glass matrix, and the glass. The glass softening point of the glass matrix contained in the ceramics is lower than the glass transition point of the flat glass, and the thermal expansion coefficient of the flat glass is equal to or higher than the thermal expansion coefficient of the glass ceramics. A cover glass with an outer frame having a temperature of 0 to 20 × 10 ^-7 / ° C., in which the flat glass and the glass ceramics are directly bonded.
[2] The cover glass with an outer frame according to the above [1], wherein the glass matrix 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% by mass of a crystal powder containing aluminum oxide as the filler component.
[4] The outside according to any one of [1] to [3] above, wherein a metal film is formed on the surface of the outer frame facing the surface to which the flat glass is joined. Cover glass with frame.
[5] The cover glass with an outer frame according to any one of [1] to [4], wherein the outer frame is provided perpendicular to the flat glass.
[6] The cover glass with an outer frame according to any one of [1] to [5], wherein the height of the outer frame is 350 μm or more and 1.5 mm or less.
[7] The flat glass has a conductive film in at least a part of the main surface on the side to which the outer frame is joined, and a metal conductor penetrating the outer frame is provided inside the outer frame. The invention according to any one of [1] to [6], wherein the metal conductor is formed and is provided perpendicular to the flat glass, and the conductive film and the metal conductor are conductive. Cover glass with outer frame.
[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 an outer frame, the height of the outer frame can be realized to be above a certain level while maintaining the airtight sealing property. Therefore, it is possible to prevent damage to the cover glass due to energy such as UV-LED and LD (laser diode) which are light sources. Moreover, since the surface of the cover glass is not damaged or cracked by heat, the reliability as a cover glass with an outer frame is very high. Such reliability is based on the viewpoints of high temperature and high humidity, resistance to heat shock, chemical resistance, and verticality, in addition to airtight sealing property.

FIG. 1 is a schematic cross-sectional view showing an example of a cover glass with an outer frame according to the present embodiment. FIG. 2 is a schematic cross-sectional view showing an example of a cover glass with an outer frame according to the present embodiment. FIG. 3 is a schematic cross-sectional view showing an example of a cover glass with an outer frame according to the present embodiment.

Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following embodiments, and can be arbitrarily modified and carried out without departing from the gist of the present invention. Further, "-" indicating a numerical range is used in the sense that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value. Further, "mass%" is synonymous with "weight%".

<Cover glass with outer frame>
As shown in FIG. 1, the cover glass 10 with an outer frame according to the present embodiment has an outer frame 2 provided on one main surface of the 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 ceramics in which a filler component is dispersed in a glass matrix, and the flat glass 1 and the glass ceramics which are the outer frame 2 are directly bonded.
The glass softening point Ts of the glass matrix contained in the glass ceramics is lower than the glass transition point Tg of the flat glass 1. Further, the coefficient of thermal expansion of the flat glass 1 is a value equal to or higher than the coefficient of thermal expansion of the glass ceramics, and the difference between them is 0 to 20 × 10 ^-7 / ° C.

Good airtight sealing can be obtained by directly joining the flat glass and the outer frame. The direct bonding means a state in which the flat glass and the outer frame are joined without interposing the adhesive layer of the organic material such as the resin layer other than the flat glass and the outer frame. When a conductive film, which is an inorganic material described later, is formed on the main surface of the flat glass, the flat glass and the outer frame are joined via the conductive film. In this case, the conductive film is treated as a structure made of an inorganic material integrated with the flat glass, and the flat glass and the outer frame are directly bonded to each other. Further, when directly joining the flat glass and the outer frame, it is not necessary to apply a voltage as in the case of anode joining, and the flat glass and the outer frame can be joined only by overlapping and heating.
Whether or not the glass is directly bonded can be determined by the absence of the adhesive layer between the flat glass and the outer frame.

In 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 flat glass. As a result, direct bonding can be performed without requiring a high temperature that damages the surface of the flat glass.
The difference between the glass transition point Tg of the flat glass and the glass softening point Ts of the glass matrix is preferably 50 ° C. or higher, more preferably 65 ° C. or higher, and more preferably 85 ° C. from the viewpoint of preventing damage to the surface of the flat glass. The above is more preferable. On the other hand, the above difference is preferably 180 ° C. or lower, more preferably 130 ° C. or lower, still more preferably 100 ° C. or lower, from the viewpoint of suppressing the increase of carbon residue during firing of the glass ceramics serving as the outer frame and impairing the insulating property. ..

The difference between the glass transition point Tg of the flat glass and the glass softening point Ts of the glass matrix is preferably in the above range, but specifically, it is preferably 550 ° C or higher, more preferably 600 ° C or higher, and more preferably 650 ° C. The above is more preferable, and the higher the value, the more preferable. On the other hand, the glass transition point Tg of the flat glass is preferably 1000 ° C. or lower, more preferably 900 ° C. or lower, still more preferably 800 ° C. or lower from the viewpoint of ease of processing. The glass transition point Tg of the flat glass is the temperature at the first inflection of the DTA chart obtained by differential thermal analysis (DTA).

The glass softening point Ts of the flat glass is preferably 700 ° C. or higher, more preferably 750 ° C. or higher, further preferably 800 ° C. or higher, and more preferably higher. On the other hand, the glass softening point Ts of the flat glass is preferably 1500 ° C. or lower, more preferably 1000 ° C. or lower, still more preferably 950 ° C. or lower, from the viewpoint of ease of processing. The glass softening point Ts of the flat glass is the temperature at the fourth inflection point of the DTA chart.

The glass softening point Ts of the glass matrix preferably has a difference from the glass transition point Tg of the flat glass in the above range, but specifically, it is preferably 800 ° C. or lower, more preferably 700 ° C. or lower, and more preferably 600 ° C. The following is more preferable. Further, the glass softening point Ts of the glass ceramics is preferably 450 ° C. or higher, more preferably 460 ° C. or higher, still more preferably 470 ° C. or higher, from the viewpoint of suppressing the increase of carbon residue during firing and impairing the insulating property. The glass softening point Ts of the glass matrix is the temperature at the fourth inflection point of the DTA chart of the glass alone.

The glass transition point Tg of the glass matrix is preferably 740 ° C or lower, more preferably 500 ° C or lower, and even more preferably 450 ° C or lower. Further, the glass transition point Tg of the glass ceramic is preferably 380 ° C. or higher, more preferably 390 ° C. or higher, still more preferably 400 ° C. or higher, from the viewpoint of suppressing the increase of carbon residue during firing and impairing the insulating property. The glass transition point Tg of the glass matrix is the temperature at the first inflection point of the DTA chart of the glass alone.

The coefficient of thermal expansion of flat glass is a value equal to or higher than the coefficient of thermal expansion of glass ceramics. That is, the difference expressed by (coefficient of thermal expansion of flat glass-coefficient of thermal expansion of glass ceramics) is 0 / ° C. or higher. Further, the above difference is 20 × 10 ^-7 / ° C. or less. This makes it possible to prevent cracks from occurring in the flat glass when the flat glass and the outer frame are directly joined.
The above difference may be 0 / ° C. or higher, but 0.5 × ^10-7 / ° C. or higher is more preferable, and 1 × ^10-7 / ° C. or higher is even more preferable. The difference may be 20 × 10 ^-7 / ° C or less, but more preferably 15 × 10 ^-7 / ° C or less, and even more preferably 10 × 10 ^-7 / ° C or less.

The coefficient of thermal expansion of flat glass is not particularly limited as long as the difference from the coefficient of thermal expansion of glass ceramics is within the above range, but 5 × 10 ^-7 / ° C or higher is used because the selectivity of glass ceramics is limited. Preferably, 30 × 10 ^-7 / ° C. or higher is more preferable, and 70 × 10 ^-7 / ° C. or higher is even more preferable. The coefficient of thermal expansion of flat glass and the coefficient of thermal expansion of glass ceramics in the present specification are average values of the ratio of elongation per 1 ° C. when glass and glass ceramics are heated in the range of 50 ° C to 350 ° C. It is a value measured by.

The coefficient of thermal expansion of glass ceramics is not particularly limited as long as the difference from the coefficient of thermal expansion of flat glass is within the above range, but since it is necessary to approach the expansion of the substrate on which the cover glass with an outer frame is mounted, 80 × It is preferably ^10-7 / ° C. or lower, more preferably 50 × ^10-7 / ° C. or lower, and even more preferably 30 × ^10-7 / ° C. or lower.

From the viewpoint of lowering the glass softening point Ts, the glass ceramics preferably contain 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% by mass or more, more preferably 60% by mass or more, from the viewpoint of lowering the glass softening point Ts of the glass matrix as compared with the glass transition point Tg of the flat glass. On the other hand, from the viewpoint of suppressing the deterioration of the weather resistance of the flat glass, the content of bismuth oxide is preferably 90% by mass or less, more preferably 80% by mass or less.
In the present specification, the content of the glass composition in the glass matrix is the content with respect to the component excluding the filler component from the glass ceramics, and is a value expressed in mass% based on the oxide.

The content of boron oxide is preferably 3% by mass or more, more preferably 10% by mass or more, and more preferably 30% by mass or more, from the viewpoint of lowering the glass softening point Ts of the glass matrix as compared with the glass transition point Tg of the flat glass. Is even more preferable. On the other hand, from the viewpoint of suppressing the deterioration of the weather resistance of the flat glass, the content of boron oxide is preferably 60% by mass or less, more preferably 55% by mass or less, still more preferably 50% by mass or less.

When both bismuth oxide and boron oxide are contained, the content of bismuth oxide is preferably higher than the content of boron oxide, and the content of boron oxide is high, from the viewpoint of suppressing the deterioration of the weather resistance of the flat glass. The content of bismuth oxide is more preferably 1/5 or less, and the total content of bismuth oxide and boron oxide is preferably 90% by mass or less.
The total content of bismuth oxide and boron oxide is preferably 3% by mass or more, more preferably 4% by mass or more, from the viewpoint of lowering the glass softening point Ts of the glass matrix as compared with the glass transition point Tg of the flat glass. 5% by mass or more is more preferable. The total content is preferably 16% by mass or less, more preferably 12% by mass or less, still more preferably 10% by mass or less, from the viewpoint of suppressing deterioration of the weather resistance of the flat glass.

As described above, examples of the glass matrix containing at least one of bismuth oxide and boron oxide include those generally referred to as bismuth oxide-based glass and borosilicate-based glass.
As the bismuth oxide-based glass, in addition to Bi ₂ O ₃ , B ₂ O ₃ , CeO ₂ , SiO ₂ , RO, _R'2 O, R''2 O ₃ , R'''O ₂ and the like _are contained. May be.
In addition, R is at least one selected from the group consisting of Zn, Ba, Sr, Mg, Ca, Fe, Mn, Cr, and Cu. R'is at least one selected from the group consisting of Li, Na, K, Cs, and Cu. R'' is at least one selected from the group consisting of Al, Fe, and La. R'''is at least one selected from the group consisting of Zr, Ti, and Sn.
Further, Al ₂ O ₃ when R'' is Al is clearly distinguished from aluminum oxide as a filler component constituting the glass ceramics. That is, the Al ₂ O ₃ content as a glass composition is excluded from the content of the crystal powder containing aluminum oxide as a filler component.

More specifically, for example, glass containing 27 to 85% by mass of Bi ₂ O ₃ and 5 to 30% by mass of B ₂ O ₃ is preferably used. This glass further contains 0 to 10% by mass of CeO ₂ , 0 to 20% by mass of SiO ₂ , 0 to 55% by mass of RO, 0 to 10% by mass of _R'2O _, and _R''2 O3. It may contain 0 to 20% by mass and R'''O ₂ in an amount of 0 to 30% by mass.

As the borosilicate glass, in addition to SiO ₂ and _B ₂ O ₃ , CeO ₂ , RO, _R'2 O, _R''2 O3, R'''O ₂ and the like may be contained. It preferably contains ZnO, _K2O , and _Na2O .
More specifically, for example, SiO ₂ is 23 to 35% by mass, B ₂ O ₃ is 40 to 55% by mass, Zn O is 10 to 20% by mass, and K ₂ O and Na ₂ O are 3 to 15 mass% in total. A glass containing% is preferably used.

Hereinafter, each component other than bismuth oxide (Bi ₂ O ₃ ) and boron oxide (B ₂ O ₃ ) will be described.
SiO ₂ is a component constituting glass. On the other hand, if it is added in an excessive amount, the glass softening point Ts may become too high.
CeO ₂ is a component that stabilizes the color tone of the glass powder after the glass raw material is melted and vitrified, and when bismuth oxide is contained, it is preferably contained together. On the other hand, if it is added in an excessive amount, it tends to crystallize and it may be difficult to obtain a stable glass powder.
The component represented by RO, including CaO, is a component that is effective in stabilizing glass and suppresses crystallization. On the other hand, if it is added in an excessive amount, the glass softening point Ts may become too high.
The component represented by _R'2 O containing K ₂ O and Na ₂ O is a component that lowers the glass softening point Ts. The smaller the atomic number, the greater the effect. However, the smaller the atomic number of the element, the lower the insulating property of the glass when the content is increased, which may impair the reliability.
The component represented by _R''2 O3 containing Al ₂ O ₃ is a component that has an effect _on stabilizing the glass, suppresses crystallization, and improves the chemical durability of the glass. On the other hand, if it is added in an excessive amount, the glass softening point Ts may become too high.
The component represented by R''''O ₂ is a component that supplies oxygen at the time of joining. On the other hand, if it is added in excess, it may foam at the time of joining.

As the filler component in the glass ceramics, at least one selected from the group consisting of aluminum oxide, zirconium oxide, titanium oxide, magnesium oxide, silicon dioxide, zirconium phosphate, β-eucriptite (LiAlSiO ₄ ) and a mixture thereof is used. A crystal powder containing aluminum oxide is preferable, and a crystal powder containing aluminum oxide is more preferable. It is more preferable that the crystalline powder contains silicon dioxide in addition to aluminum oxide.

Examples of aluminum oxide include α-alumina type, γ-alumina type, δ-alumina type, and θ-alumina type depending on the type of crystal phase, but α-alumina type in which the crystal phase has a corundum type structure is preferable.

The content of the crystal powder as a filler component in the glass ceramics, particularly the crystal powder containing aluminum oxide, is preferably 5% by mass or more, more preferably 10% by mass or more, from the viewpoint of preventing cracks in the flat glass. preferable. Further, from the viewpoint of obtaining good adhesion to the flat glass, the content of the crystal powder is preferably 40% by mass or less, more preferably 35% by mass or less, more preferably 30% by mass or less, and 25% by mass or less. Is even more preferable. 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 aluminum oxide is preferably 25% by mass or less from the viewpoint of obtaining good sinterability. The content of the crystalline powder containing aluminum oxide as a filler component in the glass ceramics is synonymous with the content with respect to the total amount of the inorganic components in the glass ceramics.

The shape of the crystalline powder is not particularly limited, such as spherical, flat, scaly, and fibrous.
The size of the crystal powder is also not particularly limited, but for example, the 50% particle size (D ₅₀ ) is preferably 0.5 μm or more, more preferably 1 μm or more, preferably 4 μm or less, and more preferably 3 μm or less. .. The 50% particle size is a value measured using a laser diffraction / scattering type particle size distribution measuring device.

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 glass ceramics and the glass softening point Ts of the glass matrix.
For example, the flat glass preferably has a transmittance of 90% or more at a wavelength of 250 to 1500 nm.

Specifically, as the flat glass, soda lime glass, borosilicate glass, aluminosilicate glass, silica glass, etc. can be used. Borosilicate glass is preferable because it can be easily processed. Further, silica glass is preferable from the viewpoint of durability and permeability.

In the cover glass 10 with an outer frame according to the present embodiment, in addition to the flat glass 1 and the outer frame 2, as shown in FIG. 1, the metal film 3, the conductive film 4, and the metal conductor 5 represented by the metal films 3a and 3b are shown. May be provided. Hereinafter, each configuration will be described in order.

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

The height of the outer frame 2 made of glass ceramics is preferably 350 μm or more, more preferably 400 μm or more, still more preferably 500 μm or more, from the viewpoint of preventing the cover glass from being damaged by the energy of light from the light source. On the other hand, the height of the outer frame is preferably 1.5 mm or less, more preferably 1.35 mm or less, still more preferably 1 mm or less, due to the demand for lower device height.

The outer frame 2 may have a metal film 3 formed on the surface of the surface facing the surface to which the flat glass 1 is bonded, and has an airtight sealing property when the cover glass with an outer frame is adhered to the substrate. It is preferable to form from the above points. Due to the presence of the metal film, the substrate and the cover glass with an outer frame can be hermetically sealed by adhesion using metal solder.

The metal film 3 may have a metal film 3b containing at least one selected from the group consisting of Au, Ag, Cu and Au—Sn alloys on the outermost surface thereof from the viewpoint of adhesiveness when using metal solder. It is preferable to have an Au film, and it is more preferable to have an Au film. As a base of such a film, a film (not shown) such as a Ni film or a Ti film may be provided.

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

Considering the use of the cover glass with an outer frame, it is preferable that the outer frame is provided perpendicular to the flat glass. The fact that the flat glass and the outer frame are vertical means that the angle between the flat glass and the outer surface of the outer frame is vertical. It should be noted that the vertical does not have to be exactly 90 °, but a substantially vertical of 90 ° ± 5 ° is sufficient.

Further, it is preferable that the cover glass with an outer frame is equipped with a system that can detect a crack in the cover glass depending on its use. As an example of the system, it is preferable that the flat glass 1 is provided with the conductive film 4 in at least a part of the main surface on the side to which the outer frame 2 is joined. Further, it is preferable that the metal conductor 5 penetrating the glass ceramics is formed inside the outer frame 2, and the conductive film 4 and the metal conductor 5 are conductive.

Conventionally known conductive films can be applied, but transparent conductive films are preferable from the viewpoint of light transmission, and examples thereof include ITO (Indium Tin Oxide) films, SnO ₂ films, and ZnO films. Above all, the ITO film is preferable from the viewpoint of durability and resistance.
The film thickness of the conductive film is not particularly limited, but is preferably 0.05 μm or more, more preferably 0.1 μm or more, still more preferably 0.2 μm or more in order to secure stable conductivity. Further, in order to maintain the permeability, the film thickness of the conductive film is preferably 1 μm or less, more preferably 0.8 μm or less, still more preferably 0.7 μm or less.

The conductive film may be formed in at least a part of the main surface of the flat glass, but for the purpose of detecting cracks in the cover glass, it is irradiated with at least an effective region, that is, light from a light source. It is preferably formed in the region to be formed, and more preferably formed on the entire one main surface of the flat glass.
When a film or layer other than the conductive film is formed on the main surface of the flat glass, it is further outside from the other films or layers, that is, the side where the substrate provided with the light source is located. It is preferable that a conductive film is formed on the outermost surface of the above.

The metal conductor 5 is sometimes referred to as a via, and means a conductor that electrically connects the upper layer wiring and the lower layer wiring. In the present embodiment, the metal conductor 5 is conductive with the conductive film 4 in order to connect the conductive film 4 and the detector for detecting the cracking of the cover glass.

Conventionally known metal conductors can be applied by conventionally known methods. For example, before or after firing the glass ceramics constituting the outer frame, a hole penetrating the inside of the outer frame is provided, and a metal conductor is laid there.

The metal conductor may be any metal having conductivity, but from the viewpoint of ease of manufacture, one or more metals selected from the group consisting of Ag, Au and Cu are preferable, and Ag is more preferable. Ease of manufacture means that when the glass ceramics used as the outer frame are fired and sintered, they can be sintered together.

The shape of the metal conductor is not particularly limited, but a metal wire is preferable from the viewpoint of facilitating penetration into the inside of the outer frame. The via diameter, which is the diameter of the metal wire, is more preferably 0.2 mm or less, and further preferably 0.1 mm or less, from the viewpoint of preventing the metal conductor from becoming uneven and cracking in the glass ceramics which is the outer frame during firing. preferable. The lower limit of the via diameter is not particularly limited, but is preferably 0.05 mm or more from the viewpoint of preventing breakage of the metal conductor.

Further, as shown in FIG. 2, the cover glass 10 with an outer frame according to 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 flat glass 1, and preferably at least on the main surface on the side where the substrate provided with the light source is located.

As the light diffusion layer, conventionally known ones can be applied, but from the viewpoint of preventing the outer frame from disappearing when firing, those made of an inorganic material are preferable, and flat glass is directly processed. However, it is more preferable in terms of preventing loss due to interfacial reflection. It is even more preferred that, for example, a plurality of concave aspherical lenses be provided by direct processing, and the aspherical lenses are even more preferably disposed without gaps in at least an effective region on the main surface of the flat glass.

The maximum size of the aspherical lens is not particularly limited, but is usually 250 μm or less, and the lower limit is usually 20 μm or more.
Further, the spreading angle, that is, the spreading angle of the emitted light of the aspherical lens when the parallel light is incident on the effective region from the lens-processed surface is preferably 30 ° or more in full angle. The upper limit of the diffusion angle is usually 85 ° or less in full width.

The antireflection film 7 is preferably formed on at least one main surface of the flat glass 1, and more preferably at least on the main surface on the side where the substrate provided with the light source is located. It is also more preferable that it is formed on both main surfaces.
When the cover glass with an outer frame includes a light diffusing layer by direct processing, it is preferable that an antireflection film is formed on the outer side of the light diffusing layer.

The antireflection film is not particularly limited as long as it has an antireflection function that reduces the reflectance of light of at least the design wavelength. The antireflection film is preferably a film formed of an inorganic material from the viewpoint of preventing it from disappearing when the outer frame is fired, for example, a thin film having a single layer structure, SiO ₂ and Ta ₂ O ₅ and the like. In addition, a multilayer film such as a dielectric multilayer film in which two or more kinds of dielectric layers having different refractive indexes are laminated can be mentioned.

The flat glass may be provided with a layer, a film or the like having some function in addition to the above, as long as the effect of the present invention is not impaired.
In the case where the flat glass is provided with a layer or film formed of an inorganic material such as a light diffusion layer, an antireflection film, or a conductive film, the layer or film extends to the bonding region with the outer frame. When formed, the flat glass and the outer frame are joined via such a layer or film. In this case as well, it is determined that the layer or film is integrated with the flat glass and that the flat glass and the outer frame are directly bonded to each other.

In the cover glass 10 with an outer frame, a part of the outer frame 2 can be cut so that the metal conductor 5 can be taken out. For example, as shown in FIG. 3, the corners can be chamfered so as to form a straight line passing through the flat glass 1 and the outer frame 2, and the metal conductor 5 can be taken out from the position indicated by the arrow. The chamfering method is not limited and a conventionally known method can be used, and examples thereof include a processing method called bevel cut for diagonally grinding and polishing.
It is advantageous that the cover glass 10 with an outer frame has a shape as shown in FIG. 3 in that the space is not restricted when the metal conductor 5 is taken out.

<Manufacturing method of cover glass with outer frame>
An embodiment of a method for manufacturing the cover glass 10 with an outer frame will be described.
The method for producing the glass ceramics to be the outer frame 2 in the cover glass with an outer frame is not particularly limited, and for example, it is obtained by forming and firing a mixture of the glass powder and the ceramic powder to obtain the sintered glass. Specific examples thereof include a method of forming the above mixture into a sheet called a green sheet and firing the mixture.

An example of a method for manufacturing a green sheet is shown below.
First, each raw material is blended so as to have a desired glass composition, and the mixed raw material mixture is melted, cooled, and pulverized to obtain a glass powder. The glass powder obtained by pulverization is fired to form a glass matrix, which determines the glass composition of the glass ceramics.

The melting temperature of the raw material mixture is preferably 1200 to 1600 ° C. or higher, and the melting time is preferably 30 to 60 minutes, for example.
The pulverization may be a dry pulverization method or a wet pulverization method. In the case of the wet pulverization method, water, ethanol or the like can be used as the solvent.
For crushing, for example, a crusher such as a roll mill, a ball mill, or a jet mill can be used.

The size of the glass powder is 0.5 μm with a 50% particle size (D ₅₀ ) from the viewpoint of preventing the glass powder from aggregating and becoming difficult to handle, and also preventing the time required for powdering from becoming long. The above is preferable, and 1 μm or more is more preferable. Further, from the viewpoint of preventing an increase in the glass softening point Ts and insufficient sintering, the 50% particle size (D ₅₀ ) is preferably 4 μm or less, and more preferably 3 μm or less.
The maximum particle size of the glass powder is preferably 20 μm or less, and more preferably 10 μm or less, from the viewpoint of obtaining good sinterability and preventing a decrease in reflectance due to residual undissolved components in the sintered body.
The particle size can be adjusted by classifying as necessary after pulverization.

Then, the glass powder and the filler component are mixed to obtain a glass ceramic composition.
Conventionally known filler components can be applied, but crystal powder containing alumina oxide is preferable. More specifically, alumina oxide powder, cordierite powder, and zirconium phosphate powder are preferable.

If necessary, an organic solvent, a plasticizer, a binder, a dispersant and the like are added to the glass-ceramic composition to prepare a slurry or a paste. Conventionally known materials can be applied to each material to be blended.
Examples of the organic solvent include alcohols, ketones, aromatic hydrocarbons and the like. More specifically, toluene, methyl ethyl ketone, methanol, 2-butanol, xylene and the like can be used, and one type of these may be used or two or more types may be mixed.
Examples of the plasticizer include adipic acid-based and phthalic acid-based. More specifically, bis (2-ethylhexyl) adipate, dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate and the like can be used.
Examples of the binder include a pyrolytic resin and the like. More specifically, acrylic resin, polyvinyl butyral and the like can be used.
Examples of the dispersant include surfactant-type dispersants. More specifically, DISPERBYK180 (trade name, manufactured by Big Chemie) or the like can be used.

A green sheet can be obtained by applying the obtained slurry or paste on a film and drying it. The thickness of the green sheet is not particularly limited and can be adjusted by the thickness at the time of application, the slurry concentration and the like.

The obtained green sheets are appropriately laminated according to the desired height of the outer frame. After that, the outer frame shape is formed by punching the inside with a drilling machine. At this time, a through hole for passing the metal conductor may also be formed.
The glass ceramic may be formed by using a mold or the like instead of the green sheet, but the green sheet is preferable because it is easy to pass the wiring through each layer.

Further, the green sheets may be produced one by one according to the desired outer frame shape, but by producing a large green sheet and punching at multiple points with a drilling machine, a large number of connected green sheets can be taken. It may be an outer frame that is a connecting board. In this case, by superimposing the green sheet on the flat plate glass and thermocompression-bonding the green sheet, the cover glass with a large number of connected outer frames in which the green sheet is made of glass ceramics can be obtained. By dividing the connected cover glass with a large number of pieces with an outer frame, a single cover glass with an outer frame can be obtained. Further, the laminated body of the green sheet may be fired independently to obtain glass ceramics in advance, and then the laminated body may be directly bonded by superimposing the laminated body on the flat glass and re-firing.

The shape of the outer frame is determined by the shape of the green sheet. That is, the shape when punching out the green sheet is the origin of the shape inside the outer frame. In addition, the outer shape of the green sheet is the origin of the outer shape of the outer frame. When dividing from a multi-layered connecting substrate, the shape at the time of dividing after firing is the outer shape of the outer frame.

A metal film is formed on one surface of the green sheet having an outer frame shape, if necessary. The metal film can be formed, for example, by applying a metal paste by a screen printing method.
Further, when the metal conductor is provided, it can be formed by filling the through hole formed in advance with, for example, a metal paste by a screen printing method.
The metal film and the metal conductor can 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 laminated on the surface of the green sheet opposite to the surface on which the metal film is formed, and integrated by thermocompression bonding to obtain a cover glass with an unsintered outer frame.
When a layer or film such as a light diffusion layer, an antireflection film, or a conductive film is formed on the main surface of the flat glass, it may be formed before overlaying the flat glass on the green sheet, or the outer frame. It may be formed after obtaining the attached cover glass. However, in the case of forming a conductive film and conducting it with a metal conductor, it is preferable to form the conductive film before overlaying the flat glass on the green sheet.

The direct bonding by thermocompression bonding after the green sheet and the flat glass 1 are overlapped is not particularly limited as long as the green sheet and the flat glass are integrated.
The temperature at the time of crimping is preferably, for example, 60 to 65 ° C. The pressure at the time of crimping is preferably, for example, 12400 to 14000 Pa. The time for crimping is preferably, for example, 5 to 10 minutes.

By degreasing the cover glass with an unsintered outer frame as desired and further firing it, the green sheet becomes glass ceramics in which the filler component is dispersed in the glass matrix, and the glass ceramics and the flat glass as the outer frame 2 are obtained. A cover glass 10 with an outer frame is obtained, which is directly joined to 1.

A metal film 3 is provided on the main surface of the outer frame on the side opposite to the side to which the flat glass is bonded, in consideration of the adhesiveness when using metal solder when adhering to the substrate. It may be formed. In that case, in addition to the metal film 3b located on the outermost surface to be adhered to the substrate, a film serving as a base for the metal film 3b, a film serving as a base, or a metal conductor 5 between the metal film 3b and the outer frame. A metal film 3a using the same metal as above may also be formed.
The metal film 3 may be formed before firing or after firing, but it is preferably formed before firing from the viewpoint of workability.

When the cover glass with an unsintered outer frame is a connecting substrate with a large number of pieces, a single cover glass with an outer frame can be obtained by cutting between adjacent holes with a dicing saw after firing.

Degreasing may be performed as needed, for example, 400 to 500 ° C. is preferable. The degreasing time is preferably 1 to 10 hours, for example.

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 ceramics and less than a temperature lower than the glass transition point Tg of the flat glass. This prevents heat damage to the surface of the flat glass.

The specific firing temperature varies depending on the glass composition of the glass ceramics, but from the viewpoint of obtaining sufficient sinterability, for example, 500 ° C. or higher is preferable, 520 ° C. or higher is more preferable, and 550 ° C. or higher is further preferable. Further, from the viewpoint of preventing the melting of metals such as metal films and metal conductors, the firing temperature is preferably 900 ° C. or lower, more preferably 750 ° C. or lower, and even more preferably 600 ° C. or lower.
The firing time is preferably 10 minutes or longer, more preferably 15 minutes or longer, still more preferably 25 minutes or longer, from the viewpoint of obtaining sufficient sinterability. From the viewpoint of productivity, the firing time is preferably 60 minutes or less, more preferably 55 minutes or less, and even more preferably 50 minutes or less.

The flat glass 1 can be produced by a conventionally known method, or a commercially available one may be used.
For example, a glass raw material is prepared and heated and melted so that a glass having a desired composition can be obtained. Then, the molten glass is homogenized by bubbling, stirring, addition of a clarifying agent, etc., molded into a glass plate having a predetermined thickness by a known molding method, and slowly cooled. After homogenizing the molten glass, it may be formed into a block shape, slowly cooled, and then cut into a flat plate shape.

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

The metal film 3 is formed on the surface of the surface facing the surface to which the flat glass of the outer frame is joined. The metal film 3a using the same metal as the metal conductor can be formed by a conventionally known method. For example, it can be formed by applying a conductive paste made into a paste by adding a vehicle such as ethyl cellulose to a metal powder and, if necessary, a solvent or the like by a screen printing method.

The metal film 3b located on the outermost surface and the film underlying the metal film 3b can also be formed by a conventionally known method, for example, by electrolytic plating. Further, it may be formed by electroless plating. From the viewpoint of cost, electrolytic plating is preferable.
Due to the presence of the metal film 3b, the substrate and the cover glass with an outer frame can be hermetically sealed by adhesion using metal solder.

The conductive film 4 can be formed on the main surface of the flat 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 flat glass, it is preferable that the conductive film is formed on the outermost surface thereof, that is, on the side closest to the substrate.

The antireflection film 7 can be formed on at least one main surface of the flat glass by using a known film forming method such as a sputtering method or a thin film deposition method. That is, the high-refractive index layer and the low-refractive index layer constituting the antireflection film are formed on the main surface of the flat glass according to the stacking order.
Examples of the sputtering method include magnetron sputtering, pulse sputtering, AC sputtering, digital sputtering and the like. Examples of the vapor deposition method include a vacuum vapor deposition method, an ion beam assist method, and an ion plating method.

The antireflection film may be formed on at least one main surface of the flat glass, and is preferably formed on at least the main surface on the side where the substrate is located. When the light diffusing layer 6 is formed on the main surface of the flat glass, it is preferable that an antireflection film is formed on the surface of the light diffusing layer.

The cover glass with an outer frame according to the present embodiment is excellent in airtight sealing property and also excellent in cost, so that it is excellent in productivity. Further, as a means for joining to the substrate, it is also possible to use a metal frit in addition to joining via a metal film.
Because of these characteristics, for example, backlights such as liquid crystal displays, light emitting parts in operation buttons of small information terminals, lighting for automobiles or decorations, deep ultraviolet light LEDs for sterilization applications, and 3D ranging sensors. It is suitable as a laser unit and other light sources.

Hereinafter, the present invention will be specifically described with reference to 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 flat glass 1, a 50 mm × 50 mm × 1.1 mm borosilicate glass plate (D263 (registered trademark) Teco manufactured by SCHOTT) was used.
The light diffusion layer 6 was formed by directly processing a plurality of concave aspherical lenses in the entire region on one main surface of the flat glass 1. The maximum size of the aspherical lens was 200 μm, and the diffusion angle was 50 ° in full angle.
Next, the antireflection film 7 was formed on both main surfaces of the flat glass 1 by a sputtering method. The antireflection film was a film having a thickness of 0.4 μm in which a layer of Ta ₂ O ₅ was formed as a high refractive index layer and a layer of SiO ₂ was formed in order as a low refractive index layer on both sides.
An ITO film having a thickness of 0.3 μm was formed as a conductive film 4 by a sputtering method in the entire region of the outermost surface of the flat glass 1 on the side where the light diffusion layer 6 was formed.
As described above, a flat glass having a light diffusion layer, an antireflection film and a conductive film was obtained.

[Example 1]
Glass raw materials are blended and mixed so as to have Bi ₂ O ₃ : 73% by mass, ZnO: 18% by mass, B ₂ O ₃ : 5% by mass, and SiO ₂ : 4% by mass in an oxide-based percentage display. The raw material mixture was prepared. This raw material mixture was placed in a platinum crucible and melted at 1600 ° C. for 60 minutes, and then the molten glass was poured out and cooled. This glass was placed in a container together with ethyl alcohol as a solvent and pulverized with 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 μm.
A glass ceramic composition was prepared by blending and mixing the obtained glass powder in an amount of 80% by mass and the cordierite powder (manufactured by Marusu Glazed Co., Ltd., trade name: SS-600) in an amount of 20% by mass. A mixture of 1 kg of glass ceramic composition with toluene: methyl ethyl ketone: methanol: 2-butanol = 3: 3: 1: 1 (mass ratio) as an organic solvent was 0.35 kg, and bis adipate (2) as a plasticizer. -Ethylhexyl) was 0.060 kg, acrylic resin was 0.447 kg as a binder, and 0.015 kg of a dispersant (manufactured by Big Chemie, trade name: DISPERBYK180) was mixed and mixed to prepare a slurry.
A green sheet was produced by applying the slurry on a polyethylene terephthalate (PET) film by the doctor blade method and drying it. The thickness per green sheet was 200 μm.

Six green sheets were laminated, and a substantially rectangular hole of 2.57 mm × 1.75 mm and a through hole having a diameter of 170 μm for forming a metal conductor were made by using a drilling machine.
Silver paste (manufactured by Daiken Kagaku Kogyo Co., Ltd., trade name: US-202A) is applied on one surface of the green sheet by the screen printing method, and the same silver paste is filled in the through holes to form an unfired metal film. 3a and the metal conductor 5 were formed.

Next, a flat glass having a light diffusion layer, an antireflection film and a conductive film was superposed on the surface of the green sheet opposite to the side on which the metal film 3a was formed. At this time, the flat glass was laminated so that the main surface on the conductive film side was joined to the green sheet.
This was integrated by thermocompression bonding at 65 ° C. and 14000 Pa to obtain a cover glass with an unsintered outer frame. Then, it was held at 450 ° C. for 2 hours for degreasing, and further held at 520 ° C. for 30 minutes for firing. By firing, the outer frame became sintered glass ceramics, and the outer frame and the flat glass were directly bonded. Then, a nickel film was formed as a base on the surface of the metal film 3a of the outer frame by a plating treatment, and a gold film was further formed by a plating treatment as the metal film 3b. As a result, a cover glass with an outer frame was obtained. The height of the outer frame was 870 μm.

[Example 2]
The glass raw material in the green sheet is expressed as an oxide-based percentage, Bi ₂ O ₃ : 72% by mass, B ₂ O ₃ : 10% by mass, ZnO: 9% by mass, BaO: 6% by mass, and SiO ₂ : 3 A cover glass with an outer frame was obtained in the same manner as in Example 1 except that the glass powder (glass B) was obtained by blending and mixing so as to have a mass%.

[Example 3, Example 5, Example 7]
The same as in Example 1 except that the cordierite powder (manufactured by Marusu Glazed Co., Ltd., trade name: SS-600) in the glass-ceramic composition was changed to the content described in the “Crystal powder” column of Table 1. Obtained a cover glass with an outer frame.

[Example 4, Example 6, Example 8]
The same as in Example 2 except that the cordierite powder (manufactured by Marusu Glazed Co., Ltd., trade name: SS-600) in the glass-ceramic composition was changed to the content described in the “Crystal powder” column of Table 1. Obtained a cover glass with an outer frame.

[evaluation]
The glass transition point Tg and glass softening point Ts of the glass matrix in flat glass and glass ceramics are the first and fourth eccentric points of the chart measured under the condition of 5 ° C./min by differential thermal analysis (DTA). It was decided from. The results are shown in Table 1.

The coefficient of thermal expansion of flat glass and glass ceramics is based on the average value of the rate of elongation per 1 ° C when measured at 5 ° C / min in the range of 50 ° C to 350 ° C by thermomechanical analysis (TMA). Decided. The results are shown in Table 1. In addition, "-" in the table means that it has not been measured.

When obtaining an external cover glass in which the flat glass and the outer frame were directly bonded by degreasing and firing from the unsintered cover glass with an outer frame, the presence or absence of cracks in the flat glass was confirmed by microscopic observation. .. The results are shown in Table 1. In addition, when the cover glass with an unsintered outer frame was fired but the outer frame was not sintered to become glass ceramics, it was described as "(not sintered)" in Table 1.

From the above results, the coefficient of thermal expansion of the flat glass is higher than the coefficient of thermal expansion of the glass ceramics, and by reducing the difference between them, the two can be directly bonded without causing cracks in the flat glass. rice field. As a result, it was confirmed that it is possible to provide a cover glass with an outer frame in which damage and cracks of the cover glass are reduced while maintaining the airtight sealing property. Further, by changing the number of laminated green sheets used as the material of the outer frame, it is possible to realize a desired value for the height of the outer frame.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. This application is based on a Japanese patent application filed on December 23, 2020 (Japanese Patent Application No. 2020-213972), the contents of which are incorporated herein by reference.

1 Flat glass 2 Outer frame 3 Metal film 3a Metal film 3b Metal film 4 Conductive film 5 Metal conductor 6 Light diffusion layer 7 Antireflection film 10 Cover glass with outer frame

Claims

A cover glass with an outer frame having an outer frame provided on one main surface of flat glass.
The outer frame is made of glass ceramics in which a filler component is dispersed in a glass matrix.
The glass softening point of the glass matrix contained in the glass ceramics is lower than the glass transition point of the flat glass.
The coefficient of thermal expansion of the flat glass is equal to or greater than the coefficient of thermal expansion of the glass ceramics, and the difference between them is 0 to 20 × 10 -7 / ° C.
A cover glass with an outer frame in which the flat glass and the glass ceramics are directly bonded.
The cover glass with an outer frame according to claim 1, wherein the glass matrix contains at least one of bismuth oxide and boron oxide.
The cover glass with an outer frame according to claim 1 or 2, wherein the glass ceramic contains 5 to 40% by mass of a crystal powder containing aluminum oxide as the filler component.
The cover glass with an outer frame according to any one of claims 1 to 3, wherein a metal film is formed on the surface of the outer frame facing the surface to which the flat glass is joined.
The cover glass with an outer frame according to any one of claims 1 to 4, wherein the outer frame is provided perpendicular to the flat glass.
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 or more and 1.5 mm or less.
The flat glass has a conductive film in at least a part of the main surface on the side to which the outer frame is joined.
A metal conductor penetrating the outer frame is formed inside the outer frame.
The metal conductor is provided perpendicular to the flat glass.
The cover glass with an outer frame according to any one of claims 1 to 6, wherein the conductive film and the metal conductor are conductive.
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.
The cover glass with an outer frame according to any one of claims 1 to 8, wherein the flat glass has a light diffusion layer on at least one main surface.