JP2009296001A - Light-emitting diode element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting diode element which has light-emitting diode sealed by glass, and which enables the light-emitting diode to be sealed by glass without using a sol gel method. <P>SOLUTION: In the light-emitting diode element, the glass 7 for sealing the light-emitting diode 1 comprises, in mol%, 30-70% SnO, 15-50% P<SB>2</SB>O<SB>5</SB>, 0.1-20% ZnO, 0-10% SiO<SB>2</SB>+GeO<SB>2</SB>, 0-30% Li<SB>2</SB>O+Na<SB>2</SB>O+K<SB>2</SB>O, 0-20% MgO+CaO+SrO+BaO, and 0-7% other components, wherein: a refractive index of the glass in wavelength of 400 nm is 1.7 or more; and an average linear expansion coefficient of the glass at 50-300°C is 75×10<SP>-7</SP>to 140×10<SP>-7</SP>/°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light emitting diode element (hereinafter referred to as an LED element) in which a light emitting diode (hereinafter referred to as an LED) is sealed with glass.

  Conventionally, incandescent bulbs, fluorescent lamps and the like have been widely used as white light sources, but in recent years, so-called white LED elements have been developed as a new type of white light source, and their application to backlights for liquid crystal displays and the like has rapidly progressed. Yes.

  In a typical one-chip white LED element currently on the market, an LED having a quantum well structure using InGaN in which GaN is added with In as a light emitting layer is sealed with a resin containing a YAG phosphor.

  The white LED element functions as a white light source as follows. That is, when a direct current is passed through the LED, blue light is emitted from the LED, while the YAG phosphor is excited by a part of the blue light, and yellow light (fluorescence) is emitted from the phosphor. This blue light and yellow light are in a complementary color relationship, and they enter and enter the human eye and appear as white light due to the principle of additive color mixing.

  However, in such a white LED element in which the LED is sealed with the resin, when it is used for a long period of time, moisture enters the resin and the operation of the LED is hindered. The resin is discolored by the ultraviolet rays emitted from the LED. There was a problem that the light transmittance was lowered.

  As a white LED element that solves such a problem, there has been proposed one in which an LED is provided on a substrate in a flip chip form and the LED is sealed with sol-gel glass (see Patent Document 1).

Japanese Patent Laid-Open No. 2002-203989 (pages 2-7)

Since the sol-gel glass has pores or pores tend to remain, LED operation inhibition due to moisture may not be sufficiently suppressed. In order to solve such a problem of pores, heat treatment is typically performed at 1300 ° C. However, heat treatment at a very high temperature such as 1300 ° C. cannot be applied to the manufacture of LED elements. there were.
An object of the present invention is to provide an LED element that does not cause such a problem, has a higher light extraction efficiency than a resin, and is not easily affected by thermal expansion.

The present invention is an LED element in which an LED is sealed with glass, and the glass is represented by mol% based on the following oxides, SnO 30 to 70%, P ₂ O ₅ 15 to 50%, ZnO 0. 1-20%, SiO ₂ + GeO ₂ 0-10%, Li ₂ O + Na ₂ O + K ₂ O 0-30%, MgO + CaO + SrO + BaO 0-20%, other components 0-7%, the refractive index of the glass at a wavelength of 400 nm Is not less than 1.7, and the average linear expansion coefficient of the glass at 50 to 300 ° C. is 75 × 10 ^{−7 to} 140 × 10 ⁻⁷ / ° C. (first invention).

Further, an LED element LED is sealed by glass, the glass is represented by mol% based on the following _{oxides, B 2 O 3 20~55%,} Bi 2 O 3 1~20%, ZnO 0 Provided is an LED element consisting essentially of ˜30%, SiO ₂ + GeO ₂ 0-20%, Li ₂ O + Na ₂ O + K ₂ O 0-30%, MgO + CaO + SrO + BaO 0-30% (second invention).

Further, an LED element LED is sealed by glass, the glass is represented by mol% based on the following _{oxides, TeO 2 20~70%, 5~30%} ZnO, B 2 O 3 0~55 %, SiO ₂ + GeO ₂ 0 to 10%, Li ₂ O + Na ₂ O + K ₂ O 0 to 30%, MgO + CaO + SrO + BaO 0 to 20% are provided (third invention).

  According to the present invention, since the LED can be sealed with glass without using the sol-gel method, the LED operation is hardly inhibited by moisture. In addition, the light extraction efficiency is high and it is not easily affected by thermal expansion.

The figure which shows an example of the cross section of the LED element of this invention.

  In any of the LED elements of the present invention, the LEDs are sealed with glass, but none of these glasses can be produced by the sol-gel method, that is, none of these glasses can be sol-gel glass.

  In the LED element of the present invention, for example, the LED is sealed by placing a glass lump of an appropriate shape on the LED and softening and flowing the glass lump. The LED is sealed using molten glass. The LED is sealed by tightly coating the LED with glass that is stopped or powdered and then softening and flowing the powdered glass. Usually, a phosphor is added to the glass lump, the molten glass or the powdered glass. Hereinafter, the glass sealing the LED (including those in which the phosphor is dispersed) may be referred to as sealing glass.

Next, although this invention is demonstrated using FIG. 1, this invention is not limited to this.
FIG. 1 is an example of a cross-sectional view of an LED element of the present invention. 1 is an LED, 2a and 2b are electrodes, 3a and 3b are lead frames, 4 is a housing, 5 is an insulating layer, 6 is a mount, and 7 is a sealing glass.

  The LED 1 typically emits ultraviolet light or blue light having a wavelength of 360 to 480 nm, and examples thereof include a quantum well structure LED (InGaN-based LED) using InGaN in which GaN is added with InGaN as a light emitting layer. The When the LED 1 is an InGaN-based LED, the portions in contact with the electrodes 2a and 2b are an n-type semiconductor and a p-type semiconductor, respectively. In addition, although the board | substrate which consists of sapphire etc. exists in the upper surface of LED1, this board | substrate is not shown in figure.

  The electrodes 2a and 2b are for passing a direct current through the LED 1, and are usually made of gold, platinum or the like, and are formed on the surfaces of the thin lead frames 3a and 3b by plating, vapor deposition or the like.

  The lead frames 3a and 3b are electrically connected by bonding or intimate contact with the electrodes 2a and 2b, respectively, and function as external connection terminals. The lead frames 3a and 3b are thin plate-like conductive materials, and it is preferable that the lead frames 3a and 3b can be easily joined or in close contact with the electrodes 2a and 2b and have excellent heat dissipation characteristics. The conductive material is typically a metal, and aluminum or an aluminum alloy is exemplified.

  The housing 4 is usually one in which a hole is formed in the center of a metal plate so that the LED 1 can be arranged. The inner surface of the hole is preferably tapered as shown in FIG. 1 in order to reflect light emitted from the LED 1 in the horizontal direction and efficiently extract it from the upper surface of the LED element. The shape of the hole is typically a circle, but is not limited thereto, and may be an ellipse, a square, or the like.

  The metal plate must be such that the shape can be stably maintained even when the temperature rises when the LED 1 is sealed with glass. The said temperature is typically 450 degrees C or less, and an aluminum plate or an aluminum alloy plate is illustrated as a suitable metal plate in such a case.

  When an aluminum plate or an aluminum alloy plate is used as the metal plate, the reflectance with respect to ultraviolet light and visible light is 90% or more, so that the light extraction efficiency from the LED element can be increased.

  Of the surfaces of the housing 4, the surface that is the outer surface of the LED element is preferably excellent in electrical insulation. Otherwise, the electrode 2a and the electrode 2b may be electrically connected or short-circuited through the surface. In order to enhance the electrical insulation of the surface, for example, when the housing 4 is aluminum or an aluminum alloy, the surface may be oxidized to be anodized.

  The insulating layer 5 is for electrically insulating the electrodes 2a, 2b and the housing 4 and is made of resin, ceramics, glass or the like, but even if the temperature rises during sealing It must be able to hold its shape stably.

  As the mount part 6, what consists of resin, ceramics, glass, etc. which are excellent in electrical insulation is illustrated. In the case where the mount portion 6 is formed at the time of sealing, it must be such that its shape can be stably maintained even when the temperature rises at the time of sealing, and preferably made of alumina, for example.

  The sealing glass 7 seals the LED 1 so that the surface of the LED 1 is not exposed to the atmosphere.

Softening point T _S of the glass used in the sealing glass 7 is preferably 450 ° C. or less. If it exceeds 450 ° C., the temperature at which the glass 1 is softened and fluidized and the LED 1 is sealed becomes too high, which may cause problems such as deterioration of the light emission characteristics of the LED 1, change in the light emission wavelength, and no light emission. More preferably, it is 400 degrees C or less, Especially preferably, it is 350 degrees C or less, Most preferably, it is 330 degrees C or less.

  The refractive index n at a wavelength of 400 nm of the glass used for the sealing glass 7 is 1.7 or more. If it is less than 1.6, the light extraction efficiency from the high refractive index substrate (for example, sapphire substrate whose n is 2.5) on the upper surface of the LED 1 is lowered. In the present invention, it is more preferably 1.7 or more, particularly preferably 1.85 or more, and most preferably 2.0 or more. The n of the glass is typically 2.3 or less.

The glass used for the sealing glass 7 preferably has a refractive index of 1.7 or more at a wavelength of 633 nm.
The temperature _TF at which the viscosity of the glass used for the sealing glass 7 reaches 10 ⁵ P is more preferably 450 ° C. or lower. If it exceeds 450 ° C., the remaining bubbles of the sealing glass 7 obtained by softening and flowing the glass to seal the LED 1 increase, and the light transmittance may be reduced. Especially preferably, it is 400 degrees C or less, Most preferably, it is 380 degrees C or less.

The average linear expansion coefficient α at 50 to 300 ° C. of the glass used for the sealing glass 7 is 75 × 10 ^{−7 to} 140 × 10 ⁻⁷ / ° C. Outside this range, for example, LED 1 may have difficulty in expansion matching with an InGaN-based LED (α is typically 85 × 10 ⁻⁷ / ° C.). More preferably, it is 135 * 10 < ^-7 > / degrees C or less.

Crystallization temperature T _C of the glass used in the sealing glass 7 is preferably 400 ° C. greater. T _C is at 400 ° C. or less, typically there is a possibility that crystals in the glass is a large amount of precipitated the light transmittance decreases at the time of sealing carried out at 450 ° C. or less. More preferably, it is 420 degreeC or more, More preferably, it is 450 degreeC or more, Especially preferably, it is 550 degreeC or more, Most preferably, it exceeds 600 degreeC. The crystallization temperature referred to in the present invention is the start of crystallization when a crystallization peak is observed when glass is pulverized and subjected to differential thermal analysis from room temperature to 600 ° C. at a heating rate of 10 ° C./min. The temperature is set to “over 600 ° C.” when no crystallization peak is observed.

T _C is preferably higher than _(T S + 60 _℃), more preferably higher than _(T S + 90 ℃).
Further, _{T C} is preferably higher than _{T F} of the glass used in the sealing glass _7, more preferably higher than _(T F + 40 ° _C.), it is particularly preferably higher than _(T F + 60 ℃).

  The light transmittance (internal transmittance) at a wavelength of 360 to 750 nm when the thickness of the glass used for the sealing glass 7 is 2 mm is preferably 70% or more.

Next, the components of the glass used for the sealing glass 7 in the first invention will be described. In the following, the glass composition will be described by simply indicating mol% as% unless otherwise specified.
SnO is a glass network former and is essential. If it is less than 30%, the glass becomes unstable. Preferably it is 45% or more. If it exceeds 70%, the glass becomes unstable, or T _S or T _F becomes too high, which makes it difficult to seal the LED 1.

P ₂ O ₅ is a glass network former and is essential. If it is less than 15%, the glass becomes unstable. If it exceeds 50%, the glass becomes unstable. When the sealing glass 7 is exposed to the atmosphere, it is preferable to improve water resistance by setting P ₂ O ₅ to 45% or less, more preferably 40% or less.

ZnO is a component for stabilizing the glass and is essential. If it is less than 0.1%, the glass becomes unstable. Preferably it is 3% or more. _{T S} becomes high at 20 percent. Preferably it is 13% or less.

The total content of SnO and ZnO is preferably 1.8 to 2.2 times the content of P ₂ O ₅ . Outside this range, the glass may become unstable. More preferably, it is 1.9 to 2.1 times.

Both SiO ₂ and GeO ₂ are not essential, but may be contained up to 10% in total for stabilizing the glass, improving water resistance, and the like. If it exceeds 10% there is a possibility _{that T S} is increased.

Li ₂ O, although Na ₂ O and _{K 2} O is not essential, but may be contained up to 30% in total for such lowering the _{T S.} If it exceeds 30%, the glass may become unstable. In the case where the sealing glass 7 is exposed to the atmosphere, it is preferable to improve the water resistance by setting the total content of Li ₂ O, Na ₂ O and K ₂ O to 10% or less.

MgO, CaO, SrO and BaO are not essential, but may be contained up to 20% in total for stabilizing the glass, improving water resistance, and the like. If it exceeds 20% there is a risk _{that T S} is increased.

  The glass used for the sealing glass 7 in the first invention consists essentially of the above components, but may contain other components as long as the object of the present invention is not impaired. In addition, when it contains the said other component, the total of the content is 7% or less.

The first invention wants to ultraviolet absorption edge of the shorter wavelength side of the glass used for sealing glass 7 (e.g. 350nm or less), desired to be the internal transmittance of 80% or more, desired to lower the T _S, etc. It is suitable for the case.

  The following glass A is illustrated as glass which should be used for the sealing glass 7 in 1st invention. The refractive index at a wavelength of 633 nm was measured as follows. That is, a plate-like sample having a size of 2 cm × 2 cm and a thickness of 1 mm, both surfaces of which were mirror-polished, was prepared, and the refractive index was measured using a refractive index measuring apparatus Model 2010 PRISM COUPLER (trade name) manufactured by Metricon.

(Glass A)
_{Composition: SnO 62%, P 2 O} 5 33%, ZnO 5%.
Glass transition point T _G : 262 ° C.
T _S : 322 ° C.
n: 1.8 (estimated value).
Refractive index at a wavelength of 633 nm: 1.77.
T _F : 360 ° C. (estimated value).
α: 135 × 10 ⁻⁷ / ° C.
T _C : Over 600 ° C.
Internal transmittance at a wavelength of 400 nm with a thickness of 2 mm: 97%.

Next, the components of the glass used for the sealing glass 7 in the second invention will be described.
B ₂ O ₃ is a glass network former and is essential. If it is less than 20%, the glass becomes unstable. In 55 percent too high _{T S,} it is difficult to seal the LED1.

Bi ₂ O ₃ is a glass network former and is a component that increases n and is essential. If it is less than 1%, the glass becomes unstable or n becomes low. If it exceeds 20%, the light transmittance, particularly the internal transmittance at a wavelength of 380 nm, may be lowered, for example, less than 70%.

ZnO is not essential, but may be contained up to 30% in order to stabilize the glass. _{T S} becomes high at 30 percent.

Both SiO ₂ and GeO ₂ are not essential, but may be contained up to 20% in total for stabilizing the glass, improving water resistance, and the like. If it exceeds 20% there is a risk _{that T S} is increased.

Li ₂ O, although Na ₂ O and _{K 2} O is not essential, but may be contained up to 30% in total for such lowering the _{T S.} If it exceeds 30%, the glass may become unstable. In the case where the sealing glass 7 is exposed to the atmosphere, it is preferable to improve the water resistance by setting the total content of Li ₂ O, Na ₂ O and K ₂ O to 10% or less.

MgO, CaO, SrO and BaO are not essential, but may be contained up to 30% in total for stabilizing the glass, improving water resistance, and the like. If it exceeds 30% there is a risk _{that T S} is increased.

  The glass used for the sealing glass 7 in the second invention consists essentially of the above components, but may contain other components as long as the object of the present invention is not impaired. In addition, when it contains the said other component, the total of the content becomes like this. Preferably it is 15% or less, More preferably, it is 7% or less.

  The second aspect of the invention is to make the ultraviolet absorption edge of the glass used for the sealing glass 7 on the short wavelength side (for example, 380 nm or less), for the internal transmittance to be 70% or more, for high n, for example, 1.6 or more It is suitable for the case of wanting to do so.

Next, the components of the glass used for the sealing glass 7 in the third invention will be described.
TeO ₂ is a glass network former and is essential. If it is less than 20%, it becomes difficult to obtain a glass having a large n. Preferably it is 40% or more. If it exceeds 70%, vitrification becomes difficult.

ZnO is a component for stabilizing the glass and is essential. If it is less than 5%, it becomes difficult to obtain homogeneous glass. Preferably it is 11% or more. _{T S} becomes high at 30 percent.

B ₂ O ₃ is not essential, but may be contained up to 55% in order to stabilize the glass, increase the internal transmittance at a wavelength of 380 nm, and the like. In 55 percent too high _{T S,} it is difficult to seal the LED1.

Both SiO ₂ and GeO ₂ are not essential, but may be contained up to 10% in total for stabilizing the glass, improving water resistance, and the like. If it exceeds 10% there is a possibility _{that T S} is increased.

Li ₂ O, although Na ₂ O and _{K 2} O is not essential, but may be contained up to 30% in total for such lowering the _{T S.} If it exceeds 30%, the glass may become unstable. In the case where the sealing glass 7 is exposed to the atmosphere, it is preferable to improve the water resistance by setting the total content of Li ₂ O, Na ₂ O and K ₂ O to 10% or less.

MgO, CaO, SrO and BaO are not essential, but may be contained up to 20% in total for stabilizing the glass, improving water resistance, and the like. If it exceeds 20% there is a risk _{that T S} is increased.

The glass used for the sealing glass 7 in the third invention consists essentially of the above components, but may contain other components as long as the object of the present invention is not impaired. In addition, when it contains the said other component, the total of the content becomes like this. Preferably it is 15% or less, More preferably, it is 7% or less.
For example, Y ₂ O ₃ may be contained up to 5% for the purpose of increasing n.

  The third invention is suitable for the case where n of the glass used for the sealing glass 7 is higher, for example, 1.65 or more.

As glass which should be used for the sealing glass 7 in 3rd invention, glass B1-B4 shown to a table | surface is illustrated. TeO ₂ from _Y 2 column mol% composition to _{O 3, T G} and _{T C} are units of ° C., the unit of α is ^{10 -7} / ° C., the value of the thickness 2mm internal transmittance at a wavelength of 400 nm (unit :%). Incidentally, T _C, and α is an estimate calculated from the composition.

  The LED element of the present invention preferably uses a flip chip system as shown in FIG. 1, and preferably does not use a wire bonding system.

The glass A was melted, a small amount was dropped on a carbon plate and cooled to obtain a glass sphere having a diameter of about 4 mm.
On the other hand, a petri dish aluminum pan (diameter 5 mm, height 5 mm), which is an accessory of the differential thermal analyzer TG / DTA6300 manufactured by Seiko Instruments Inc., is prepared, and an alumina plate (size: size: 2 mm × 2 mm, thickness: 1 mm) was placed, and the glass sphere was placed on the alumina plate.

  Next, after holding at 400 ° C. for 1 hour using an electric furnace, natural cooling was performed. When the aluminum pan was taken out after cooling, the glass spheres softened and flowed, and the alumina plate was sealed, and no bubbles or cracks were observed in the sealing glass, and it was extremely transparent. It was.

The alumina plate is made of high-purity alumina, and α is 85 × 10 ⁻⁷ / ° C., which is close to α of sapphire used for the substrate of the LED, and is considered to sufficiently imitate the LED.

  According to the present invention, an LED element having a higher light extraction efficiency than that of a resin and less susceptible to thermal expansion can be obtained.

1: LED
2a, 2b: electrodes 3a, 3b: lead frame 4: housing 5: insulating layer 6: mount portion 7: sealing glass

Claims (7)

A light-emitting diode element in which a light-emitting diode is sealed with glass, and the glass is represented by mol% based on the following oxide, SnO 30 to 70%, P ₂ O ₅ 15 to 50%, ZnO 0.1 to 0.1%. 20%, SiO ₂ + GeO ₂ 0-10%, Li ₂ O + Na ₂ O + K ₂ O 0-30%, MgO + CaO + SrO + BaO 0-20%, other components 0-7%, and the refractive index of the glass at a wavelength of 400 nm is 1 A light-emitting diode device having an average linear expansion coefficient of 75 × 10 ^{−7 to} 140 × 10 ⁻⁷ / ° C. at 50 to 300 ° C.   2. The light emitting diode element according to claim 1, wherein the light emitting diode is an InGaN light emitting diode.   The light emitting diode element according to claim 1 or 2, wherein the glass has a softening point of 450 ° C or lower. 4. The light-emitting diode element according to claim 1, wherein a temperature at which the viscosity of the glass becomes 10 ⁵ P is 450 ° C. or less.   The light-emitting diode element according to any one of claims 1 to 4, wherein the crystallization temperature of the glass is higher than 400 ° C.   The light-emitting diode element according to claim 1, wherein the light-emitting diodes are connected in a flip-chip manner.   The light-emitting diode element according to claim 6, wherein a housing is provided around the light-emitting diode.

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