(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2006/0113906 A1
`Ogawa
`(43) Pub. Date:
`Jun. 1, 2006
`
`US 2006O113906A1
`
`(54)
`
`(76)
`
`(21)
`
`LIGHT EMITTING DEVICE AND METHOD
`FOR MANUFACTURING THEREOF
`
`Inventor: Satoru Ogawa, Anan-shi (JP)
`Correspondence Address:
`SMITH PATENT OFFICE
`1901 PENNSYLVANIAAVENUE NW
`SUTE 901
`WASHINGTON, DC 20006 (US)
`Appl. No.:
`11/288,352
`
`(22)
`
`Filed:
`
`Nov. 29, 2005
`
`(30)
`
`Foreign Application Priority Data
`
`Nov. 29, 2004
`
`(JP)...................................... 2004-344484
`
`Publication Classification
`
`(51) Int. Cl.
`(2006.01)
`HOIL 33/00
`(52) U.S. Cl. .............................................................. 313/512
`
`ABSTRACT
`(57)
`A light emitting device having excellent thermal resistance
`and light resistance is provided. The light emitting device is
`manufactured by disposing a Substrate electrode having a
`predetermined conductive pattern provided thereon to a
`Substrate of a ceramic; flip-chip mounting a light emitting
`element having an n-side electrode and a p-side electrode on
`a common Surface side onto the Substrate electrode in a
`face-down manner and electrically connecting thereto; heat
`ing a glass to a temperature from the glass transition
`temperature to below the melting point of the glass, until the
`glass shows its softened State; and fixing the softened glass
`to the Substrate by way of pressing to cover the light emitting
`element with the glass.
`
`
`
`12
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`Patent Application Publication Jun. 1, 2006 Sheet 1 of 23
`
`US 2006/011.390.6 A1
`
`
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`Patent Application Publication Jun. 1, 2006 Sheet 2 of 23
`
`US 2006/011.390.6 A1
`
`Fig. 2
`
`
`
`12
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`Patent Application Publication Jun. 1, 2006 Sheet 3 of 23
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`US 2006/0113906 A1
`
`Fig. 3
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`Patent Application Publication Jun. 1, 2006 Sheet 4 of 23
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`US 2006/011.390.6 A1
`
`Fig. 4
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`Patent Application Publication Jun. 1, 2006 Sheet 5 of 23
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`US 2006/011.390.6 A1
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`Patent Application Publication Jun. 1, 2006 Sheet 6 of 23
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`US 2006/011.390.6 A1
`
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

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`Patent Application Publication Jun. 1, 2006 Sheet 7 of 23
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`US 2006/011.390.6 A1
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`Patent Application Publication Jun. 1, 2006 Sheet 8 of 23
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`US 2006/011.390.6 A1
`
`Fig. 8
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`Patent Application Publication Jun. 1, 2006 Sheet 9 of 23
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`US 2006/011.390.6 A1
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`Fig. 9
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

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`Patent Application Publication Jun. 1, 2006 Sheet 10 of 23
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`US 2006/011.390.6 A1
`
`Fig. 10
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`Patent Application Publication Jun. 1, 2006 Sheet 11 of 23
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`US 2006/011.390.6 A1
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`Fig. 11
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

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`Patent Application Publication Jun. 1, 2006 Sheet 12 of 23
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`US 2006/011.390.6 A1
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`Fig. 12
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
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`

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`Patent Application Publication Jun. 1, 2006 Sheet 13 of 23
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`US 2006/011.390.6 A1
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`Fig. 13
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`Patent Application Publication Jun. 1, 2006 Sheet 14 of 23
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`US 2006/0113906A1
`
`Fig. 14
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

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`Patent Application Publication Jun. 1, 2006 Sheet 15 of 23
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`US 2006/011.390.6 A1
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

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`Patent Application Publication Jun. 1, 2006 Sheet 16 of 23
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`US 2006/011.390.6 A1
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`Fig. 16
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`Patent Application Publication Jun. 1, 2006 Sheet 17 of 23
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`US 2006/011390.6 A1
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

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`Patent Application Publication Jun. 1, 2006 Sheet 18 of 23
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`US 2006/011.390.6 A1
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

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`Patent Application Publication Jun. 1, 2006 Sheet 19 of 23
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`US 2006/011.390.6 A1
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`Fig. 19
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
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`

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`Patent Application Publication Jun. 1, 2006 Sheet 20 of 23
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`US 2006/011.390.6 A1
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`Fig. 20
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

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`Patent Application Publication Jun. 1, 2006 Sheet 21 of 23
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`US 2006/0113906A1
`
`Fig. 21
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
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`

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`Patent Application Publication Jun. 1, 2006 Sheet 22 of 23
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`US 2006/011.390.6 A1
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`Fig. 22
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
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`

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`Patent Application Publication Jun. 1, 2006 Sheet 23 of 23
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`US 2006/011.390.6 A1
`
`Fig. 23
`Prior Art
`
`2030
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`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`US 2006/01 1390.6 A1
`
`Jun. 1, 2006
`
`LIGHT EMITTING DEVICE AND METHOD FOR
`MANUFACTURING THEREOF
`
`BACKGROUND OF THE INVENTION
`0001) 1. Field of the Invention
`0002 The present invention relates to a light emitting
`device used in a backlight of a portable telephone, a display
`capable of showing various data, a light source for various
`sensors such as a line sensor, an indicator, and to a light
`emitting device used for an indication of various measuring
`instruments and outdoor guide plates. The present invention
`especially relates to a light emitting device having a high
`reliability and one that exhibits excellent heat resistance and
`light stability.
`0003 2. Discussion of the Related Art
`0004. In a conventional light emitting device, a light
`emitting element is mounted on a predetermined substrate
`and an encapsulating member is disposed to cover the light
`emitting device. The light emitting element is bonded to a
`desired member Such as a lead frame or a printed wiring
`Substrate, and molded with an encapsulating member which
`is made of a light-transmissive resin. An organic material,
`Such as epoxy resin and silicone resin, is usually used for the
`encapsulating member. With this light emitting device, light
`is emitted from the light emitting element by applying
`electric current to the light emitting element. The emitted
`light penetrates the encapsulating member Such as an epoxy
`resin and is transmitted through the air.
`0005. When an encapsulating member of an organic
`material. Such as epoxy resin and silicone resin, is used to
`cover the light emitting element, there have been cases
`where the organic material deteriorates due to the heat and
`light generated from the light emitting element. There have
`also been cases where a component in an organic material
`causes deterioration of a printed wiring Substrate, an elec
`trode, and the like. As a result, a decrease in the optical
`characteristics, the electric characteristics, and the reliability
`characteristics of the light emitting device may occur.
`0006. A chip-type light emitting device has been known,
`in which an organic material Such as epoxy resin is replaced
`with a low-melting point glass in order to solve such a
`problem. (For instance, see Japanese Unexamined Patent
`Publication Nos. 11-177129, 2002-203989, and 2004
`200531.) FIG. 23 is a schematic cross-sectional view show
`ing a conventional chip-type light emitting device 2000. In
`the chip-type light emitting device 2000, a light emitting
`element 2010 bonded to a printed wiring substrate 2020 is
`covered with an encapsulating member 2030 of a low
`melting point glass. Lead glass is used for the low-melting
`point glass. The melting point of lead glass is about 400° C.
`Melting or hardening lead glass at a temperature of about
`400° C. does not affect the properties of the light emitting
`element 2010. The chip-type light emitting device 2000 is
`manufactured by bonding the light emitting element 2010 to
`the predetermined printed wiring substrate 2020. An elec
`trode of the light emitting element 2010 and a wiring base
`2021 are wire-bonded using a wire 2090. The printed wiring
`substrate 2020 having the light emitting element 2010
`bonded thereto is covered with a predetermined metal mold.
`A hole for injecting an encapsulating member is made in the
`metal mold. A liquefied low-melting point glass flows into
`
`the metal mold from the hole and is then hardened to bond
`to a material Substrate. After bonding, the metal mold is
`removed, and by cutting to a predetermined size, the chip
`type light emitting device 2000 is obtained.
`0007. However, when manufacturing the conventional
`light emitting device 2000, the low-melting point glass is
`melted into a liquid, so that when the low-melting point
`glass is hardened, disconnection of wire 2090 or detachment
`of the light emitting element 2010 from the printed wiring
`substrate 2020 may occur. This is due to the differences in
`the expansion coefficients of the printed wiring Substrate
`2020 and the low-melting point glass that is the encapsu
`lating member 2030 when hardening the low-melting point
`glass. Moreover, the low-melting point glass has a low light
`extraction efficiency. This is because the low-melting point
`glass has a color and a portion of the emitted light from the
`light emitting element 2010 is absorbed by the colored
`portion of the low-melting point glass. Further, the low
`melting point glass is susceptible to heat and humidity and
`its chemical stability is low.
`
`SUMMARY OF THE INVENTION
`0008. It is, therefore, an object of the present invention to
`provide a light emitting device having excellent heat resis
`tance and light stability. Another object of the present
`invention is to provide a simplified manufacturing method
`with excellent mass productivity for the light emitting
`device.
`0009. After performing various tests to solve the prob
`lems described above, the inventor has achieved the present
`invention.
`0010. The present invention relates to a light emitting
`device comprising a light emitting element having a couple
`of positive and negative electrodes disposed thereon, a
`Substrate having the light emitting element mounted thereon
`and the substrate having a substrate electrode, with the
`electrodes of the light emitting element being electrically
`connected to the Substrate electrode, and a glass covering the
`light emitting element and having a glass transition tem
`perature (Tg) of from 200° C. to 700° C.
`0011. The present invention also relates to a manufactur
`ing method for a light emitting device comprising the steps
`of mounting a light emitting element having a pair of
`positive and negative electrodes on a Substrate having a
`Substrate electrode, and electrically connecting the elec
`trodes of the light emitting element with the substrate
`electrode; heating the glass to a temperature from the glass
`transition temperature or higher to the melting point of the
`glass or below; pressing the glass against the Substrate
`having the light emitting element mounted thereon, and
`cooling the glass.
`0012. In the present specification, “face-down” depicts a
`mounting form in which an active device side of a light
`emitting element or a chip is downwardly connected.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`0013 FIG. 1 is a schematic perspective view showing a
`light emitting device according to a first embodiment.
`0014 FIG. 2 is a schematic plan view showing the light
`emitting device according to the first embodiment.
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`US 2006/01 1390.6 A1
`
`Jun. 1, 2006
`
`FIG. 3 is a schematic cross-sectional view (1)
`0.015
`showing a manufacturing method of the light emitting
`device according to the first embodiment.
`0016 FIG. 4 is a schematic cross-sectional view (2)
`showing the manufacturing method of the light emitting
`device according to the first embodiment.
`0017 FIG. 5 is a schematic cross-sectional view (3)
`showing the manufacturing method of the light emitting
`device according to the first embodiment.
`0018 FIG. 6 is a schematic cross-sectional view (4)
`showing the manufacturing method of the light emitting
`device according to the first embodiment.
`0.019
`FIG. 7 is a schematic cross-sectional view (5)
`showing the manufacturing method of the light emitting
`device according to the first embodiment.
`0020 FIG. 8 is a schematic cross-sectional view (6)
`showing the manufacturing method of the light emitting
`device according to the first embodiment.
`0021
`FIG. 9 is a schematic cross-sectional view (7)
`showing the manufacturing method of the light emitting
`device according to the first embodiment.
`0022 FIG. 10 is a schematic cross-sectional view show
`ing a light emitting device according to a second embodi
`ment.
`0023 FIG. 11 is a schematic cross-sectional view show
`ing a light emitting device according to a third embodiment.
`0024 FIG. 12 is a schematic cross-sectional view show
`ing a light emitting device according to a fourth embodi
`ment.
`FIG. 13 is a schematic cross-sectional view show
`0.025
`ing a light emitting device according to a fifth embodiment.
`0026 FIG. 14 is a schematic cross-sectional view show
`ing a light emitting device according to a sixth embodiment.
`0027 FIG. 15 is a schematic cross-sectional view show
`ing a light emitting device according to a seventh embodi
`ment.
`0028 FIG. 16 is a schematic cross-sectional view show
`ing a light emitting device according to an eighth embodi
`ment.
`0029 FIG. 17 is a schematic cross-sectional view show
`ing a light emitting device according to a ninth embodiment.
`0030 FIG. 18 is a schematic plan view showing a light
`emitting device according to a tenth embodiment.
`0031
`FIG. 19 is a schematic cross-sectional view show
`ing a light emitting device according to the tenth embodi
`ment.
`0032 FIG. 20 is a schematic plan view showing a light
`emitting device according to an eleventh embodiment.
`0033 FIG. 21 is a schematic cross-sectional view show
`ing a light emitting device according to the eleventh embodi
`ment.
`0034 FIG. 22 is a schematic cross-sectional view show
`ing a light emitting device according to a twelfth embodi
`ment.
`
`0035 FIG. 23 is a schematic cross-sectional view show
`ing a conventional light emitting device.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`0036 Preferred embodiments and examples of the light
`emitting device and the manufacturing method thereof
`according to the present invention will now be described in
`detail below. However, the scope of the present invention is
`not construed to be limited by the disclosed embodiments
`and examples.
`0037. The present invention relates to a light emitting
`device comprising a light emitting element having a pair of
`positive and negative electrodes on a common Surface side,
`a substrate whereon the light emitting element is to be
`mounted, and a Substrate electrode disposed on the Substrate.
`The light emitting element is bonded face-down to the
`substrate electrode. The electrodes of the light emitting
`element and the substrate electrode are electrically con
`nected. The light emitting element is covered with a glass.
`Further, a gas intervenes between the light emitting element
`and the Substrate. With this arrangement, a light emitting
`device having excellent heat resistance and light stability
`and the like can be provided. Moreover, because the light
`emitting element is bonded face-down, problems such as
`detachment of wires do not occur. Further, light is mainly
`extracted from the opposite side of the electrodes of the light
`emitting element, so that light is not blocked by the elec
`trodes.
`0038. In the organic materials such as epoxy resin and
`silicone resin used as the encapsulating member in the
`conventional light emitting devices, deterioration can occur
`due to exposure to heat and light for a long time. To counter
`this effect, glass is used in the present invention, so that
`deterioration caused by heat or light will be extremely little.
`0039. Furthermore, during manufacturing of the conven
`tional light emitting device, a low-melting point glass, which
`is the encapsulating member, is heated into a liquid and
`injected, so a gas is not included between the light emitting
`device and the substrate. In the present invention, a softened
`glass which is below its melting point is used. Therefore,
`very little glass will get in between the light emitting
`element and the Substrate, and so a gas intervenes therebe
`tween. Neither a liquid nor a solid substance intervenes
`between the light emitting element and the substrate. There
`fore, when the glass is pressed in order to fix the light
`emitting element to the Substrate, no pressure from the liquid
`or the solid substance will be applied to the light emitting
`element. Since the light emitting element is a semiconductor
`light emitting element, it is very sensitive and it is possible
`to be severely damaged by a liquid or a solid Substance.
`0040. The present invention also relates to another light
`emitting device comprising a light emitting element having
`a pair of positive and negative electrodes on a common
`Surface side, a Substrate whereon the light emitting element
`is to be mounted, and a substrate electrode disposed on the
`substrate. The light emitting element is bonded face-down to
`the substrate electrode. The electrodes of the light emitting
`element and the substrate electrode are electrically con
`nected via a bump. The light emitting element is covered
`with a glass. Further, an insulating member is disposed
`between the light emitting element and the substrate.
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`US 2006/01 1390.6 A1
`
`Jun. 1, 2006
`
`Because the light emitting element is electrically connected
`with the substrate electrode, the insulating member is used
`to prevent short-circuiting. With this arrangement, a light
`emitting device having excellent heat resistance, light sta
`bility, and the like can be provided. Further, by disposing the
`insulating member between the light emitting element and
`the substrate, heat dissipation can be improved. This is
`because heat generated from the light emitting element is
`transmitted to the insulating member, and is further trans
`mitted to the substrate.
`0041. The present invention also relates to another light
`emitting device comprising a light emitting element having
`a pair of positive and negative electrodes on a common
`Surface side, a substrate whereon the light emitting element
`is to be mounted, and a Substrate electrode disposed on the
`substrate. The light emitting element is bonded face-down to
`the substrate electrode. The electrodes of the light emitting
`element and the substrate electrode are electrically con
`nected. The light emitting element is covered with a glass,
`and the glass is pressed to fix it to the substrate. With this
`arrangement, a light emitting device having excellent heat
`resistance, light stability, and the like can be provided.
`0042. In the conventional light emitting devices, because
`a low-melting point glass is used during the manufacturing
`process as the encapsulating member and is heated into a
`liquid and injected, disconnection of the wires and detach
`ment of the light emitting element have occurred due to
`differences in the expansion coefficients of the low-melting
`point glass and the Substrate as the glass hardens. However,
`in the present invention, the glass is pressed when it is in a
`softened State at a temperature lower than its melting point.
`Therefore, the differences in the expansion coefficients do
`not become a problem, and the problems such as detachment
`of the light emitting element do not arise. Also, the light
`emitting element is bonded face-down and a wire is not
`required. Therefore, the problems such as disconnection of
`the wires do not arise even when the glass is pressed.
`0043. The present invention also relates to a light emit
`ting device comprising a light emitting element having a pair
`of positive and negative electrodes on a common Surface
`side, a Substrate whereon the light emitting element is to be
`mounted, and a Substrate electrode disposed on the Substrate.
`The light emitting element is bonded face-down to the
`substrate electrode. The electrodes of the light emitting
`element and the substrate electrode are electrically con
`nected. The light emitting element is covered with a glass,
`and the glass has a glass transition temperature (Tg) of 200
`C. to 700° C. With this arrangement, a light emitting device
`having excellent heat resistance and light stability and the
`like can be provided.
`0044) A low-melting point glass which is the encapsu
`lating member in the conventional light emitting devices has
`a glass transition temperature of about 100° C. to 150° C.
`and it softens when a heat of 100° C. to 150° C. or above is
`applied thereto. When a voltage is applied to the light
`emitting element, heat is generated and the temperature of
`the light emitting element may rise to about 120° C. There
`fore, in some cases, when a Voltage is applied to the light
`emitting element, the low-melting point glass softens or is
`predisposed to soften, resulting in a poor heat resistance.
`0045. In the present invention, the glass transition tem
`perature is 200° C. or above. Therefore, the glass does not
`
`soften and stays in the glass state at the range of tempera
`tures caused by the heat generated from the light emitting
`element. Thus, a light emitting device having an encapsu
`lating member with excellent heat resistance can be pro
`vided.
`0046) The present invention also relates to a light emit
`ting device comprising a light emitting element having a pair
`of positive and negative electrodes on a common Surface
`side, a Substrate whereon the light emitting element is to be
`mounted, and a Substrate electrode disposed on the Substrate.
`The light emitting element is bonded face-down to the
`substrate electrode. The electrodes of the light emitting
`element and the substrate electrode are electrically con
`nected. Further, the light emitting element is covered with a
`glass, and the glass has a glass transition temperature (Tg)
`of 200° C. to 700° C. and a melting point of 220° C. or
`above. With this arrangement, a light emitting device having
`excellent heat resistance and light stability and the like can
`be provided. The glass used in the present invention stays in
`the softened State without liquefying at temperatures toler
`able to the light emitting element, the electrodes, the sub
`strate electrode, the substrate of the light emitting element,
`and a bump which electrically connects the light emitting
`element and the substrate, and the like. With this arrange
`ment, problems such as detachment of the light emitting
`element are prevented. Moreover, destruction of the light
`emitting element and the bump is prevented.
`0047 Lead-free glass has a glass transition temperature
`of 200° C. to 700° C., and a melting point of at least 220°
`C. Lead glass has a glass transition temperature of 300° C.
`to 700° C., and a melting point of at least 410° C.
`0048. A low-melting point glass containing lead and used
`as the encapsulating member in the conventional light
`emitting devices has a melting point of 400° C. or less and
`liquefies when heated to at least 400° C. As a result,
`problems such as disconnection of the wires and the like
`arise in conventional light emitting devices. However, even
`when the glass used in the present invention is heated to over
`400° C., it does not liquefy and in some cases, it softens.
`Therefore, the problems such as detachment of the light
`emitting element are not caused.
`0049. The present invention also relates to a light emit
`ting device comprising a light emitting element having a pair
`of positive and negative electrodes on a common Surface
`side, a Substrate whereon the light emitting element is to be
`mounted, and a Substrate electrode disposed on the Substrate.
`The light emitting element is bonded face-down to the
`substrate electrode. The electrodes of the light emitting
`element and the substrate electrode are electrically con
`nected. The light emitting element is covered with a glass,
`and a side surface of the glass is polished or cut. With this
`arrangement, a light emitting device having excellent heat
`resistance and light stability and the like can be provided.
`0050. Both of the organic materials such as an epoxy
`resin and the low-melting point glass which are the encap
`Sulating members in the conventional light emitting devices
`are in liquid form at the time of molding. Therefore, a means
`of dropping the organic material or the low-melting point
`glass onto the light emitting element and hardening it by
`using Surface tension is adopted. An alternative means
`includes pouring the organic material or the low-melting
`point glass into a predetermined metal mold, putting the
`
`EVERLIGHT ELECTRONICS CO., LTD.
`Exhibit 1011
`
`

`

`US 2006/01 1390.6 A1
`
`Jun. 1, 2006
`
`light emitting element therein and hardening it. Neither
`means requires polishing or cutting.
`0051. In the present invention, a predetermined glass
`plate and the like is heated to its softened state and is fixed
`onto the Substrate whereon a plurality of light emitting
`elements have been mounted. Therefore, a cutting step so as
`to separate each light emitting element is required. Also, the
`light extracting efficiency can be improved by polishing.
`Further, by polishing or by cutting, light can be extracted in
`a predetermined direction using the differences in the refrac
`tive indices of the glass and the air.
`0.052 The present invention also relates to a light emit
`ting device comprising a light emitting element having a pair
`of positive and negative electrodes on a common Surface
`side, a Substrate whereon the light emitting element is to be
`mounted, and a Substrate electrode disposed on the Substrate.
`The light emitting element is bonded face-down to the
`substrate electrode. The electrodes of the light emitting
`element and the substrate electrode are electrically con
`nected. The light emitting element is covered with a glass,
`and an upper surface of the glass is polished. With this
`arrangement, a light emitting device having excellent heat
`resistance and light stability and the like can be provided.
`0053 A predetermined glass plate and the like is heated
`to its softened state and is fixed onto the substrate whereon
`a plurality of light emitting elements have been mounted.
`Because the glass is planar, polishing can be carried out with
`ease, so that the light emitting devices can be provided with
`minimal differences between the products. Moreover, even
`in a case where a little irregularity occurred on the Surface
`of the glass, by polishing, the light emitting device having a
`predetermined orientation characteristic can be provided.
`Also, the light extraction efficiency can be improved by
`polishing. Further, by polishing or by cutting, light can be
`extracted in a predetermined direction using the difference in
`the refractive indices between the glass and the air. Further,
`because the light emitting element is mounted face-down, by
`polishing the Substrate of the light emitting element and the
`Surface of the glass approximately in parallel, light can also
`be extracted in a predetermined direction.
`0054) The substrate is preferably a ceramic. With this
`arrangement, a light emitting device having excellent heat
`resistance and light stability and the like can be provided,
`and further, the manufacturing step of pressing the glass can
`be endured by the light emitting element.
`0055. It is preferable that a recess defined by a bottom
`surface and a side surface is formed in the substrate and the
`substrate electrode is disposed in the bottom surface of the
`recess. The side surface of the recess preferably has a shape
`of a reversed truncated cone widening towards the opening.
`With this arrangement, light from the light emitting element
`irradiating the side surface of the recess is reflected from it
`and emitted to outside. Also, light from the light emitting
`element irradiating the substrate electrode disposed in the
`bottom surface of the recess is reflected from it and emitted
`to the outside. With this arrangement, the frontal luminous
`intensity can be improved.
`0056. A lenticular glass may be used as the above
`described glass. With this arrangement, the light emitting
`device having a predetermined distribution of light can be
`provided.
`
`0057 The glass preferably contains 100 ppm or less, or
`substantially no lead. With this arrangement, the substance
`that has a harmful effect on the environment can be
`excluded. However, because lead glass has a beautiful glaze
`and sheen, a lead glass may also be used in the light emitting
`device of the present invention.
`0058. The glass may contain at least one material selected
`from the group consisting of a fluorescent material, a pig
`ment, a filler, a light diffusing member, and a ceramic
`powder. With this arrangement, the light emitting device
`complying with intended application can be provided. For
`example, by using a blue-light emitting light emitting ele
`ment and a glass containing a yellow-emitting fluorescent
`material, a light emitting device which emits white light can
`be provided. Also, by using a light diffusing member, a light
`emitting device capable of emitting uniform light with little
`irregularity in color can be provided.
`0059. The light emitting element may also be covered
`with a covering member and the covering member may be
`covered with a glass. The light emitting element may be
`directly covered with a glass. Additionally, the light emitting
`element may be covered with a covering member and then
`the covering member may be covered with a glass. With this
`arrangement, the light emitting element can be protected
`from heat and dust and the like.
`0060. The covering member may contain at least one
`material selected from the group consisting of a fluorescent
`material, a pigment, a filler, a light diffusing member, and a
`ceramics powder. With this arrangement, the light emitting
`device complying with intended application can be pro
`vided. It is cost-effective because the fluorescent material
`and the like can be disposed in the vicinity of the light
`emitting element so that the amount of the fluorescent
`material used can be reduced. Also, the covering member
`can be made into liquid or molten state, so that the dispers
`ibility of the materials can be improved.
`0061. In the light emitting device, a protective element
`may be disposed on the substrate. With this arrangement,
`damage to the light emitting element caused by a reverse
`current can be prevented.
`0062. In the light emitting device, it is preferable that a
`protective element is disposed on the side opposite to the
`side whereon the light emitting element is mounted. With
`this arrangement, even a protective element using a wire can
`be used.
`0063. It is preferable that a coating is further provided to
`the glass. With this arrangement, discoloration of the glass
`can be reduced. Also, a predetermined function can be
`added. Examples of Such a coating include a coating having
`a filter