JP2009010206A - Glass for coating light-emitting element, and glass-coated light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass for coating light emitting elements capable of sealing optical elements at a temperature about 500°C, and to provide a glass-coated light-emitting device which is coated with the glass. <P>SOLUTION: The glass for coating light-emitting elements is essentially constituted of, in terms of oxide-based mol% denotation, 41-55% TeO<SB>2</SB>, 16-33% B<SB>2</SB>O<SB>3</SB>, and 22-50% ZnO, having an average linear expansion coefficient at a temperature of 50-300°C of 120×10<SP>-7</SP>/°C or lower, having a glass transition temperature of 420°C or lower, and practically does not contain fluorine. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to glass, in particular, glass used for coating a light emitting element (for example, a light emitting diode) and a glass-coated light emitting device coated with the glass.

  Conventionally, a resin such as an epoxy resin, silicone, or fluororesin has been mainly used as a member for covering the light emitting element. However, the above-described members have insufficient luminous efficiency, and it has been difficult to employ conventional light emitting devices as general lighting or automobile headlights. Therefore, glass has been attracting attention as a member to be coated (Patent Document 1, Patent Document 2).

Japanese Patent Laid-Open No. 7-330372 US Patent Publication Number: 2006 / 0231737A1

However, both glass patents 1 and 2 composed of a small number of compositions disclose glasses that substantially contain a composition other than the three compositions of TeO ₂ , B ₂ O ₃ and ZnO. . The smaller the number of compositions constituting the glass, the cheaper it can be produced, the desired average linear thermal expansion coefficient (120 × 10 ⁻⁷ / ° C. or less) at 50 to 300 ° C. and the glass transition point (420 ° C. or less). In addition, it is difficult to determine the distribution amount of each composition for overcoming devitrification suppression, and the light-emitting element was encapsulated with glass substantially containing a composition other than the above three compositions. Specifically, TeO ₂ has a problem that if the content is small, the refractive index is decreased or the glass transition point is increased, and if it is larger, the average linear expansion coefficient is increased. Further, B ₂ O ₃ has a problem that if the content is small, the glass becomes unstable, while if it is large, the refractive index is decreased or the chemical durability such as water resistance is lowered. In addition, ZnO has a problem that if its content is low, it makes the glass unstable and easily devitrified, while if it is high, ZnO may have to be melted at a temperature above 980 ° C. For this reason, it has not been very easy to determine the contents of the glass composed substantially of only three compositions. Therefore, Patent Document 1 contains fluorine (element symbol: F) instead of determining the subtle content. However, fluorine is an expensive material, and there is a problem that the price of the finished glass-covered light-emitting device increases. Further, the glass described in Patent Document 2 has a glass transition point (Tg) of 420 ° C. or higher, and there is a problem that the light emitting element cannot be sealed at 500 ° C. or lower.

One mode of a light-emitting element for covering glass of the present invention is composed of only three compositions of ZnO and TeO ₂ and B ₂ O ₃ to remove impurities contained in each composition, the average linear thermal at 50 to 300 ° C. The expansion coefficient is 120 × 10 ⁻⁷ / ° C. or less, and the glass transition point is 420 ° C. or less.

In addition, a glass-coated light-emitting device of one embodiment of the present invention includes a substrate, a bonded member mounted on the substrate, TeO ₂ , B ₂ O _3, and ZnO ternary glass that seals the bonded member. It is characterized by having.

According to the present invention, without much increasing the average linear expansion coefficient, it is possible to lower the glass transition point, TeO ₂ and B ₂ O ₃ and real ZnO capable of sealing the light-emitting element at around 500 ° C. It is possible to provide a glass for light-emitting element coating composed of three target compositions and a glass-coated light-emitting device coated with the glass.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the figure, corresponding parts are indicated by corresponding reference numerals. The following embodiment is shown as an example, and various modifications can be made without departing from the spirit of the present invention.

  First, a glass-coated light-emitting device will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of the glass-coated light-emitting device of the present invention. In the glass-coated light-emitting device of the present invention, a light-emitting element (for example, a light-emitting diode) 100 that is a bonded member, a glass 110 that is a coating member that covers the light-emitting element 100, and a wiring 130 on which the light-emitting element 100 is mounted are formed. Substrate 120.

The light emitting element 100 includes a substrate 101, an LED 102, a plus electrode 103, and a minus electrode 104. The LED 102 is an LED that emits ultraviolet light or blue light having a wavelength of 360 to 480 nm, and is an LED having a quantum well structure (InGaN-based LED) using InGaN in which In is added to GaN as a light emitting layer. The average linear expansion coefficient (α) of the substrate 101 is 70 × 10 ^{−7 to} 90 × 10 ⁻⁷ / ° C. Usually, a sapphire substrate having an average linear expansion coefficient (α) of about 80 × 10 ⁻⁷ / ° C. is used as the substrate 101.

  Next, the light emitting element coating glass of the present invention will be described.

  The glass transition point (Tg) of the glass for covering a light emitting device of the present invention is preferably 420 ° C. or lower, more preferably 410 ° C. or lower.

The average linear expansion coefficient (α) at 50 to 300 ° C. of the light emitting device coating glass of the present invention is 120 × 10 ⁻⁷ / ° C. or less, more preferably 116 × 10 ⁻⁷ / ° C. or less, particularly preferably 115 × 10. ^{It is −7} / ° C. or lower. In addition, the average linear expansion coefficient ((alpha)) in 50-300 degreeC raises a glass transition point, if it is less than 70x10 < ^-7 > / degreeC. Preferably, it is 75 × 10 ⁻⁷ / ° C. or higher.

  Hereinafter, the composition of the glass for covering a light-emitting element of the present invention will be described with mol% simply expressed as%.

TeO ₂ is a glass network former and is essential. If it is 40% or less, the refractive index becomes small, or the glass transition point is raised. Preferably it is more than 40%, particularly preferably 43% or more. If it exceeds 55%, the average linear expansion coefficient becomes large. Preferably it is 50% or less, Most preferably, it is 48% or less.

B ₂ O ₃ is a component that forms a glass skeleton and is essential. If it is less than 10%, the glass becomes unstable. Preferably it is 15% or more, particularly preferably 17% or more. If it is 33% or more, the refractive index becomes small, or the chemical durability such as water resistance decreases. Preferably it is less than 33%, particularly preferably 30% or less.

  ZnO is a component that stabilizes the glass and is essential. If it is 22% or less, the glass becomes unstable and tends to devitrify. Preferably it is more than 22%, particularly preferably 25% or more. If it exceeds 50%, it may be necessary to dissolve at a temperature exceeding 980 ° C. Preferably it is 40% or less, Most preferably, it is 36% or less.

In the present invention, (B ₂ O ₃ + ZnO) / TeO ₂ is preferably 1.0 or more. If it is less than 1.0, the average linear thermal expansion coefficient is larger than 120 × 10 ⁻⁷ / ° C., and there is a possibility that the glass breaks at the portion in contact with the element after sealing the LED. If it exceeds 1.5, the glass transition point is raised or the chemical durability such as water resistance is lowered. Preferably it is 1.4 or less.

In the present invention, it is preferable that TeO ₂ + B ₂ O ₃ + ZnO is substantially 100%. That is, the light emitting element coating glass of the present invention is composed of three components of TeO ₂ , B ₂ O ₃ and ZnO. Therefore, since the glass for covering a light emitting device of the present invention is composed of three components, it is easy to manage the composition variation of the glass at the time of mass production, and it is possible to reduce the variation of various physical property values. Here, that it is substantially 100%, to remove impurities contained in the three components of ZnO and TeO ₂ and _B 2 _{O 3,} other component is not more than 1.0% of the total content of means.

The glass for coating an optical element of the present invention consists essentially of the above-mentioned three components, but other components such as Y ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , and the like as long as the object of the present invention is not impaired. Bi ₂ O ₃ , BaO, WO ₃ , GeO ₂ , TiO ₂ , Ga ₂ O ₃ , Ta ₂ O _5, etc. may be added at an upper limit of 10%. In addition, it is preferable that the glass of this invention does not contain PbO substantially. In addition, it is preferable that the glass of this invention can melt | dissolve and manufacture at the temperature of 980 degrees C or less. Otherwise, it would be difficult to melt the glass using a gold crucible (melting point: 1063 ° C.), and it would have to be melted using a platinum or platinum alloy crucible. There exists a possibility that the transmittance | permeability may fall by melt | dissolving.

  The substrate 120 is, for example, a rectangular alumina substrate having a purity of 98.0% to 99.5% and a thickness of 0.5 mm to 1.2 mm. If possible, a square alumina substrate having a purity of 99.0% to 99.5% and a thickness of 0.7 mm to 1.0 mm is preferable. The wiring 130 formed on the surface of the substrate 120 is a gold wiring manufactured by a gold paste.

  About Examples 1-16, a raw material is prepared so that it may become a composition shown by mol% in a table | surface, and a 100-g preparation raw material is prepared. Next, this blended raw material was put into a gold crucible having a capacity of 100 cc and dissolved at 920 ° C. for 1 hour. At this time, the molten glass was homogenized by shaking and stirring the crucible several times. The homogenized molten glass was poured out into a carbon mold and formed into a plate shape. The plate-like glass was immediately put in another electric furnace at 410 ° C., kept at that temperature for 1 hour, and then cooled to room temperature over 12 hours.

  Here, Examples 1 to 14 are Examples, and Examples 15 to 17 are Comparative Examples.

About the obtained glass, glass transition point Tg (unit: ° C), yield point At (unit: ° C), and average linear expansion coefficient α (unit: ^10-7 / ° C) were measured by the following measuring method.
Tg: 150 mg of a sample processed into a powder form was filled in a platinum pan and measured with a thermal analyzer TG / DTA6300 (trade name) manufactured by Seiko Instruments Inc.
At: A sample processed into a cylindrical shape having a diameter of 5 mm and a length of 20 mm was measured at a rate of temperature increase of 5 ° C./min using a thermomechanical analyzer DILATOMETER 5000 (trade name) manufactured by Mac Science.
α: A sample processed into a cylindrical shape having a diameter of 5 mm and a length of 20 mm was measured at a heating rate of 5 ° C./min using the thermomechanical analyzer. The expansion coefficient at 50 to 300 ° C. was determined in increments of 25 ° C., and the average value was taken as α.
Presence or absence of devitrification: When the glass melt is poured into a carbon mold, devitrification may occur in several minutes until the glass is solidified. A surface that was partially clouded was indicated by Δ.

  The results are shown in Tables 1 and 2.

Example 1
The glass of Example 1 was processed into a glass plate having a thickness of 1.5 mm and a size of 3 mm × 3 mm, and then both surfaces thereof were mirror-polished.

On the other hand, an alumina substrate (thickness: 1 mm, size: 14 mm × 14 mm) on which a gold wiring pattern is formed and a LED made by Toyoda Gosei (product name: E1C60-0B011-03) with connection bumps are prepared. The LED was flip-chip mounted on an alumina substrate. And in order to suppress the bubble which generate | occur | produces in the interface of glass and a board | substrate, the alumina board | substrate which mounted LED was put into the electric furnace (IR heating apparatus), and it heat-processed at 620 degreeC. The temperature rising rate was set to 300 ° C./min, the holding time at 620 ° C. was set to 2 minutes, and the temperature decreasing rate was set to 300 ° C./min. Note that bubbles generated at the interface between the glass and the substrate are generated when the glass is softened in response to organic contaminants attached to the substrate surface. Since the generated bubbles refract light emitted from the light emitting element, there is a possibility that the luminance of the light emitting device is lowered or the light distribution of the light emitting device is changed. Therefore, before covering the LED with glass, the substrate on which the LED is mounted is heated to reduce organic contaminants adhering to the substrate surface, thereby suppressing the generation of bubbles. According to numerous experiments, the heating temperature is preferably around 600 ° C. The heating time is preferably around 2 minutes considering the influence of heat on the LED.

  A glass with a phosphor-dispersed glass plate placed on this flip-chip mounted LED is placed in an electric furnace, heated to 500 ° C. at a rate of 25 ° C. per minute and held at that temperature for 5 minutes to soften the glass plate. The LED was coated by flowing. Thereafter, cooling was performed at a rate of 25 ° C. per minute.

  When the glass covering the LED was visually observed, no bubbles were found near the surface.

  When a DC voltage was applied to the glass-coated LED element thus obtained, blue light emission was confirmed.

  The emission start voltage was 2.4 V, which was the same as that for the bare chip. This shows that the LED element light emitting layer is not damaged.

(Example 2)
The plate-shaped glass of Example 1 was cut to produce a block (block) of 8 to 25 mm in one piece. Several of these blocks were crushed with an alumina mortar to obtain glass powder. Although the maximum particle size of this glass powder was not measured, it is estimated that it is 50 micrometers or less from the result of visual observation.

  37.5 g of this glass powder was mixed with 5 g of a yellow phosphor P46-Y3 (cerium-added YAG powder) manufactured by Kasei Optonics Co., to prepare a mixed powder.

  42.5 g of the mixed powder and 5 blocks (total mass = 62.5 g) were placed in a gold crucible with a capacity of 100 cc and held in an electric furnace at 650 ° C. for 5 minutes to simultaneously remelt the glass. The phosphor was dispersed in the molten glass.

  After 5 minutes, the crucible was taken out, and the molten glass in which the phosphor was dispersed was poured out into a carbon mold to form a plate having a thickness of about 7 mm. The plate-like glass was immediately put in another electric furnace at 410 ° C., kept at that temperature for 1 hour, and then cooled to room temperature over 12 hours.

  As in Example 1, when the LED element was covered and a DC voltage was applied, white light emission was confirmed.

  In FIG. 1, the glass 110 has a hemispherical shape and is formed so as to be in contact with the wiring 130 formed on the substrate 101. However, as shown in FIG. 2, it is needless to say that the glass 110 may have a spherical shape so that the side surface of the light emitting element 100 is sealed and does not contact the wiring 130. Here, the spherical shape means a shape in which a part of the sphere is missing, and means a surface area that is larger than the surface area of the hemisphere having the same diameter and smaller than the surface area of the sphere having the same diameter.

  The glass for light emitting element coating of this invention can be utilized for sealing of the LED element used for a general lighting or a headlight for motor vehicles.

It is sectional drawing of the glass-coated light-emitting device of this invention. It is sectional drawing of the other glass-coated light-emitting device of this invention.

Explanation of symbols

100: Light emitting element 110: Glass 120: Substrate

Claims (8)

Consists only three compositions of ZnO and TeO ₂ and _B 2 _{O 3} to remove impurities contained in each composition, the average linear thermal expansion coefficient at 50 to 300 ° C. is 120 × ^{10 -7} / ℃ less, glasses A glass for covering a light-emitting element having a transition point of 420 ° C. or lower. In mol% display based on oxide,
TeO ₂ 41-55%,
B ₂ O ₃ 16~33%,
ZnO 22-50%
Characterized in that the average linear thermal expansion coefficient at 50 to 300 ° C. is 120 × 10 ⁻⁷ / ° C. or lower, the glass transition point is 420 ° C. or lower, and substantially does not contain fluorine. Element coating glass. The light-emitting element coating glass is expressed in mol% based on the following oxides:
TeO ₂ 41-50%
B ₂ O ₃ 16-32%
The glass for covering a light-emitting element according to claim 1 or 2, wherein ZnO is 22 to 44%. _{TeO 2 + B 2 O 3 +} ZnO is emitting element coated glass according to claim 2 or 3, characterized in that substantially 100%. A substrate,
A bonded member mounted on the substrate;
A glass-covered light-emitting device comprising ternary glass of TeO ₂ , B ₂ O _3, and ZnO that seals the member to be bonded. The glass according to claim 5, wherein the ternary glass is composed of TeO ₂ 41 to 55%, B ₂ O ₃ 16 to 33%, and ZnO 22 to 50% in terms of mol% based on oxide. Coated light emitting device. The ternary glass is expressed in terms of mol% based on the following oxides:
TeO ₂ 41-50%
B ₂ O ₃ 16-32%
The glass-coated light-emitting device according to claim 6, wherein ZnO is 22 to 44%. The glass-coated light-emitting device according to claim 7, wherein the ternary glass has an average linear thermal expansion coefficient of 120 × 10 ⁻⁷ / ° C. or less and a glass transition point of 420 ° C. or less.

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