JP2008300536A - Glass coated light emitting element, and glass coated light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass coated light emitting element and a glass coated light emitting device which are coated with glass having a coefficient of thermal expansion little different from that of the light emitting element and also having its glass transition point suppressed to a low value. <P>SOLUTION: The glass coated light emitting element includes a semiconductor light emitting element having a principal surface and P<SB>2</SB>O<SB>5</SB>-ZnO-SnO based glass covering the principal surface of the semiconductor light emitting element, wherein the glass includes essentially, by mole based on oxides, 20 to 45% P<SB>2</SB>O<SB>5</SB>, 20 to 50% ZnO and 20 to 40% SnO, and has a glass transition point of 290 to 450°C and a coefficient of thermal expansion of ≤105×10<SP>-7</SP>/°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical element, and more particularly to a glass-coated optical element (light-emitting diode) and a glass-coated light-emitting device that are coated with low-melting glass.

In recent years, TeO ₂ -based glass containing TeO ₂ as a main composition has been proposed as a member for covering a light emitting element. However, TeO ₂ type glass used as the covering member has poor transmittance at 400nm or less, it was not suitable as a sealing material for LED short wavelength (365~405nm) (UV-LED) .

In addition, there is a document describing the use of P ₂ O ₅ —ZnO-based glass as a sealing material for LEDs for short wavelengths (Patent Document 1).

International Publication Number WO2004 / 082036

However, Patent Document 1 does not describe the content of the glass composition, and there is no disclosure that can be implemented. Further, the glass of Patent Document 1 has a thermal expansion coefficient of 11.4 × 10 ⁻⁶ / ° C., and the thermal expansion coefficient of sapphire mainly used as a laminated substrate of a light emitting element (typically GaN) (approximately 80 × 10 ⁻⁷ / ° C.), which is not practical as a sealing material. Furthermore, the glass of patent document 1 does not contain Sn essentially as a composition. Therefore, there is a problem that the glass transition point of the glass of Patent Document 1 is increased.

A glass-coated optical element of one embodiment of the present invention includes a semiconductor light-emitting element having a main surface and a P ₂ O ₅ —ZnO—SnO-based glass that covers the main surface of the semiconductor light-emitting element.

The glass-coated light-emitting device of one embodiment of the present invention includes a substrate having a main surface, a main surface and a back surface opposite to the main surface, and the main surface of the substrate facing the main surface of the substrate. It includes a semiconductor light emitting element provided on the surface and a P ₂ O ₅ —ZnO—SnO-based glass covering the main surface of the semiconductor light emitting element.

  According to the present invention, it is possible to provide a glass-coated light-emitting element and a glass-coated light-emitting device that are coated with glass having a small difference in thermal expansion coefficient from that of the light-emitting element and having a low glass transition point.

  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 an adherend member, a glass 110 that is a covering 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) having InGaN in which In is added to GaN as a light emitting layer. The thermal expansion coefficient (α) of the substrate 101 is 70 × 10 ^{−7 to} 90 × 10 ⁻⁷ / ° C. Usually, a sapphire substrate having a thermal expansion coefficient (α) of about 80 × 10 ⁻⁷ / ° C. is used as the substrate 101.

  Next, the glass for coating an optical element of the present invention will be described.

The glass transition point (Tg) of the glass for coating an optical element of the present invention is preferably 290 ° C. or higher, more preferably 300 ° C. or higher, and particularly preferably 320 ° C. or higher. In the glass transition point (Tg) of less than 290 ° C., containing the ZnO is reduced, and / or will contain a large amount of P ₂ O _5, there is a possibility that water resistance is deteriorated. Preferably it is 400 degrees C or less, More preferably, it is 360 degrees C or less. As Tg increases, the sealing temperature also increases.

The thermal expansion coefficient (α) of the glass for coating an optical element of the present invention is 105 × 10 ⁻⁷ / ° C. or less, more preferably 95 × 10 ⁻⁷ / ° C. or less, and particularly preferably 90 × 10 ⁻⁷ / ° C. or less. is there. If the thermal expansion coefficient (α) is less than 70 × 10 ⁻⁷ / ° C., the glass transition point is raised. Preferably, it is 75 × 10 ⁻⁷ / ° C. or higher. In addition, when the thermal expansion coefficient (α) ^exceeds 105 × 10 ⁻⁷ / ° C., the portion that is in contact with the light emitting element of glass during or after the process of softening the glass to seal the light emitting element and cooling to room temperature As a starting point, cracks may occur, reducing the light extraction efficiency or exposing the light emitting element to atmospheric moisture.

  The mass reduction rate in the water resistance test of the glass for covering an optical element of the present invention is preferably 50% or less, more preferably 1% or less, and particularly preferably 0%. In addition, if the mass reduction rate in the water resistance test of the glass for covering optical elements exceeds 50%, chemical stability may be deteriorated.

  Hereinafter, the glass composition used in the glass-coated optical element and the glass-coated light emitting device of the present invention will be described with mol% simply expressed as%.

P ₂ O ₅ is a component that stabilizes the glass and is essential. If it is less than 20%, vitrification may be difficult. Preferably it is 20% or more, more preferably 25% or more, and particularly preferably 28% or more. On the other hand, if it exceeds 45%, the water resistance of the mounting portion may be lowered. Preferably it is 45% or less, More preferably, it is 37% or less, Most preferably, it is 35% or less.

  ZnO is a component that stabilizes the glass, such as improving water resistance and reducing the thermal expansion coefficient, and is essential. If it is less than 20%, the thermal expansion coefficient is too large, the consistency with the thermal expansion coefficient of the glass plate cannot be obtained, and there is a possibility that the glass sheet is likely to break. Preferably, it is 20% or more, more preferably 25% or more, and particularly preferably 30% or more. On the other hand, if it exceeds 50%, devitrification tends to precipitate, and the softening point becomes too high. Preferably it is 50% or less, More preferably, it is 45% or less, Most preferably, it is 42% or less.

  SnO has the effect of increasing the fluidity, and if it is less than 20%, the softening point becomes too high and the fluidity deteriorates, so that the strength and airtightness of the mounting portion may be lowered. Preferably it is 20% or more, more preferably 22% or more, and particularly preferably 25% or more. On the other hand, if it exceeds 50%, vitrification becomes difficult. Preferably it is 50% or less, more preferably 40% or less, and particularly preferably 35% or less.

The glass used in the glass-coated optical element and the glass-coated light-emitting device of the present invention consists essentially of the above-mentioned components, but other components such as MgO, CaO, SrO, BaO, B are within the range that does not impair the object of the present invention. ₂ O ₃ , Al ₂ O ₃ , Bi ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , Ce ₂ O ₃ , In ₂ O ₃ , CeO ₂ , TiO ₂ , TeO ₂ , SiO ₂ , Ta ₂ O ₅ , WO ₃ or the like may be added. In addition, it is preferable that the glass of this invention does not contain PbO substantially.

  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. 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.

For Examples 1 to 9, a normal phosphoric acid aqueous solution (85% H ₃ PO ₄ ) and ZnO and SnO powder raw materials were prepared so as to have a composition represented by mol% in the table, and after dehydration, normal phosphoric acid There is prepared an amount that the total is 100g of all components in a condition that the _P 2 _{O 5.} Next, the powder raw material and about 1 g of saccharose are mixed and mixed with about 200 ml of ion-exchanged water in a Teflon (registered trademark) container to prepare a slurry. While stirring the slurry with a Teflon (registered trademark) stirrer, a normal phosphoric acid aqueous solution is mixed. At that time, there is an exotherm due to the reaction, so it is necessary to carefully and slowly pour the normal phosphoric acid aqueous solution so that no sudden boiling of water occurs. Subsequently, the mixture was poured into a stainless steel vat with a Teflon (registered trademark) sheet, and then dried at 200 ° C. for 3 hours with ventilation to obtain a cookie-like solid.

  The solid matter was put in a quartz crucible, a quartz lid was placed, and the solid matter was melted at 1100 ° C. for 40 minutes. At this time, the molten glass was homogenized by stirring several times with a quartz rod. 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 380 ° C., kept at that temperature for 1 hour, and then cooled to room temperature over 12 hours.

  Here, Examples 1 to 8 are examples, and Example 9 is a comparative example.

About the obtained glass, glass transition point Tg (unit: ° C.) and thermal expansion coefficient α (unit: 10 ⁻⁷ / ° C.) were measured by the following measuring method.

  Tg: 250 mg of a sample processed into a powder form was filled in a platinum pan, and measured with Thermo Plus TG8110 (trade name) manufactured by Rigaku Corporation.

  α: 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 10 ° C./min using a thermal dilatometer (Horizontal differential detection type thermal dilatometer TD5010 manufactured by Bruker AXS). did. The expansion coefficient at 25 to 250 ° C. was determined in increments of 25 ° C., and the average value was taken as α.

  Water resistance test (%): A sample processed into a cylindrical shape having a diameter of 5 mm and a length of 20 mm was immersed in warm water at 80 ° C. for 3 hours, and weight loss was measured.

Transmission spectrum: about two plate-like samples having both sides mirror-polished, size 2 cm × 2 cm, thickness 1 mm and 5 mm, using a spectrophotometer U-3500 (trade name) manufactured by Hitachi, Ltd. from a wavelength of 300 nm The transmittance for light of 800 nm is measured in increments of 1 nm. T @ 1 mm and T @ 10 mm (unit:%) are calculated according to the following equations, where T ₁ and T ₅ are the transmittances of the plate samples having a thickness of 1 mm and 5 mm obtained by the measurement, respectively.
T @ 1 mm = 100 × exp [(1/4) × ln (T ₅ / T ₁ )]
T @ 10 mm = 100 × exp [10 × (1/4) × ln (T ₅ / T ₁ )].

  Determination of UV transmission: T @ 1 mm at 365 nm of 90% or more was evaluated as ◯.

  The results are shown in Table 1.

  The glass of Example 3 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 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 the flip-chip mounted LED is placed in an electric furnace, heated to 490 ° C. at a rate of 100 ° C. per minute, held at that temperature for 2 minutes, and the glass plate is softened. The LED was coated by flowing. Thereafter, cooling was performed at a rate of 100 ° 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 light emission starting voltage was 2.4 to 2.6 V, which was almost the same as that for the bare chip. This shows that the LED element light emitting layer is not damaged.

Here, the internal transmittance at an arbitrary thickness is estimated by measuring the transmittance of two glasses having different thicknesses, calculating the reflection correction value, and determining the relationship between the transmittance and the thickness. It was. As a result, the internal transmittance of the glass of Example 3 at a thickness of 1 mm with respect to light having a wavelength of 365 nm is 97%. Further, the internal transmittance of the glass of Example 3 at a thickness of 10 nm with respect to light having a wavelength of 365 nm is 74%. On the other hand, the internal transmittance of the conventional TeO ₂ glass at a thickness of 1 mm for light with a wavelength of 365 nm and a thickness of 10 mm for light with a wavelength of 365 nm is 77% and 8%. As described above, according to the glass-coated optical element and the glass-coated light-emitting device using the P ₂ O ₅ —ZnO—SnO-based glass of the present invention, the glass-coated optical element and the glass-coated light-emitting device using the conventional TeO ₂ -based glass. Compared with the device, the internal transmittance for light of a short wavelength (365 to 405 nm) is greatly improved. Therefore, the glass-coated optical element and the glass-coated light-emitting device using the P ₂ O ₅ —ZnO—SnO-based glass of the present invention can be used as a UV-LED.

  The glass for coating an optical element of the present invention can be used for sealing LED elements used for backlight light sources for liquid crystal panels, general illumination, automobile headlights, and the like.

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

Explanation of symbols

100: Light emitting element 110: Glass 120: Substrate

Claims (6)

A semiconductor light emitting device having a main surface;
A glass-covered light-emitting element comprising: a P ₂ O ₅ —ZnO—SnO-based glass that covers the main surface of the semiconductor light-emitting element. The glass-coated light-emitting element according to claim 1, wherein a glass transition point of the P ₂ O ₅ —ZnO—SnO-based glass is 450 ° C. or less. The P ₂ O ₅ —ZnO—SnO glass is
In mol% display based on oxide,
P ₂ O ₅ 20~45%,
ZnO 20-50%,
SnO 20-40%,
The glass-coated light-emitting element according to claim 2, wherein the glass-coated light-emitting element has a glass transition point of 290 ° C. or higher and a thermal expansion coefficient of 105 × 10 ⁻⁷ / ° C. or lower.   The glass-coated light emitting device according to claim 3, wherein the SnO is 20 to 35%. _2. The glass-coated light emitting device according to claim 1, wherein a weight reduction rate of the P ₂ O ₅ —ZnO—SnO-based glass in a water resistance test is 50% or less. A substrate having a main surface;
A semiconductor light emitting device having a main surface and a back surface opposite to the main surface, the semiconductor light emitting element provided on the main surface of the substrate such that the back surface faces the main surface of the substrate;
A glass-coated light-emitting device comprising: a P ₂ O ₅ —ZnO—SnO-based glass that covers the main surface of the semiconductor light-emitting element.

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