JP2007294988A - Substrate for mounting light emitting device, and light emitting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for mounting a light emitting device capable of making the thickness and surface topology of sealing resin filled up in the recess portion of a ceramic substrate almost uniform for each light emitting device. <P>SOLUTION: The substrate for mounting the light emitting device has, on the surface of a ceramic substrate 1, a recess portion 1a where the light emitting device is accommodated. On the surface of the ceramic substrate 1, a frame-shaped layer 6 including a metallized layer is adhered surrounding the recess portion 1a. Meanwhile, on the inner wall surface of the recess portion 1a, a reflecting film 3 including the metallized layer is adhered. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light-emitting element mounting substrate and a light-emitting device that are used to accommodate light-emitting elements such as light-emitting diodes.

  In recent years, light-emitting elements such as light-emitting diodes have been widely used as light sources for electric display panels, for example, due to the improvement in light emission luminance.

Such a light emitting element is used in a state of being housed in a light emitting element mounting substrate for accommodating the light emitting element.

  Conventionally, a light emitting element mounting substrate for accommodating such a light emitting element is formed by forming a recess for accommodating the light emitting element on the upper surface of a ceramic substrate formed by laminating a plurality of insulating layers.

  A metal reflection film is applied to the inner wall surface of the concave portion to reflect light emitted from the light emitting element, thereby substantially increasing the light emission luminance of the light emitting element. The light emitted from is bright and shining, and the characters and images displayed on the electric display board are bright and extremely clear. In addition, a wiring layer is applied from the bottom surface of the recess to the outside so that power supplied from an external electric circuit is supplied to the light emitting element to emit light with a predetermined light emission luminance. The element is mounted and fixed via a conductive adhesive, and each electrode of the light emitting element is electrically connected to the wiring layer, and then a transparent sealing resin such as epoxy resin is filled in the recess to make the light emitting element airtight. The light-emitting device as a product is formed by sealing, and the light-emitting display plate is formed by arranging the light-emitting devices in a matrix.

  However, according to the conventional light emitting element mounting substrate, when the light emitting element is hermetically sealed by filling the recess with a transparent sealing resin such as epoxy resin, the sealing resin is applied to the ceramic substrate. Due to its wettability, the upper surface of the ceramic substrate spreads out and tends to flow out of the recesses, so that the thickness and surface shape of the sealing resin filled in the recesses vary greatly between light emitting devices. As a result, the light emitted from the light emitting element in each light emitting device constituting the electroluminescent display board is refracted unevenly by the respective sealing resin, and characters and images displayed on the light emitting display board are unclear. It had the problem that it would be a bad thing.

  The present invention has been devised in view of such conventional problems, and its purpose is to make the thickness and surface shape of the sealing resin filled in the recesses of the ceramic substrate substantially uniform in each light emitting device. Thus, it is an object of the present invention to provide a light-emitting element mounting substrate capable of making characters and images displayed on an electric display panel using these light-emitting devices extremely clear.

  The light emitting element mounting substrate of the present invention is a light emitting element mounting substrate having a recess in which the light emitting element is accommodated on the upper surface of the ceramic substrate, and a frame-like layer including a metallized layer is formed on the upper surface of the ceramic substrate. A reflective film including a metallized layer is applied to an inner wall surface of the concave portion so as to surround the concave portion.

  Furthermore, the frame-like metallized layer is characterized in that a hollow portion that opens to the inner peripheral side is formed between the inner periphery and the outer periphery.

  A light-emitting device of the present invention comprises the light-emitting element mounting substrate, a light-emitting element placed in a recess of the light-emitting element mounting substrate, and a sealing resin filled in the recess. It is what.

  According to the substrate for mounting a light emitting element of the present invention, a frame-like metallized layer surrounding the recess for accommodating the light-emitting element is deposited on the upper surface of the ceramic substrate, and this frame-like metallized layer is wetted by the sealing resin. Since it is difficult, it is possible to satisfactorily prevent a large amount of the sealing resin from spreading on the upper surface of the ceramic substrate when the sealing resin is filled in the recess.

  Further, if a hollow portion opened on the inner peripheral side is provided between the inner periphery and the outer periphery of the frame-shaped metallized layer, the sealing resin is filled when the sealing resin is filled in the recess. Even if there is a slight excess, the excess sealing resin is accommodated in a hollow provided in the frame-like metallized layer, and the sealing resin in the recess is kept extremely constant with high accuracy. It can be a thickness.

  Next, the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a cross-sectional view showing an embodiment of a light emitting element mounting substrate according to the present invention. In the figure, 1 is a ceramic substrate, 2 is a wiring layer, 3 is a metal reflection film, 4 is a light emitting element, and 5 is a light emitting element. A sealing resin 6 is a frame-like metallized layer.

  The ceramic substrate 1 is formed by laminating a plurality of insulating layers made of a ceramic material such as an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a silicon nitride sintered body, or a glass-ceramic. It is a substantially square box shape. A concave portion 1a for accommodating the light emitting element 4 is provided at the center of the upper surface, and the light emitting element 4 is bonded and fixed in the concave portion 1a via the conductive adhesive 7 and is transparent epoxy resin. The sealing resin 5 made of is filled.

  According to the substrate for mounting a light emitting element of the present invention, a light emitting device as a product is obtained by housing the light emitting element 4 in the recess 1 a of the ceramic substrate 1 and filling the sealing resin 5. And the electroluminescent display board is formed by arranging the light-emitting devices in a matrix, for example.

  If such a ceramic substrate 1 is made of, for example, an aluminum oxide sintered body, an organic binder, a solvent, a plasticizer, and a dispersant suitable for raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide. The ceramic slurry obtained by adding and mixing the like is formed into a sheet by using a conventionally known doctor blade method to obtain a plurality of ceramic green sheets, and then the light-emitting elements 4 are accommodated in the ceramic green sheets. For example, the ceramic green sheets are laminated, and finally the laminated body is fired at a high temperature.

  In addition, a plurality of wiring layers 2 led out from the bottom surface of the concave portion 1a to the outside are deposited on the ceramic substrate 1. The wiring layer 2 functions as a conductive path for supplying electric power supplied from an external electric circuit to the light emitting element 4, and each electrode of the light emitting element 4 is electrically connected via the conductive adhesive 7. .

  Such a wiring layer 2 is made of metal powder metallization such as tungsten, molybdenum, manganese, copper, and silver. For example, a metal paste obtained by adding an appropriate organic binder and solvent to metal powder such as tungsten is mixed with the ceramic substrate 1. The ceramic green sheet for printing is printed and applied by using a well-known screen printing method, and is fired together with a laminate of ceramic green sheets for the ceramic substrate 1 from the bottom surface of the recess 1a of the ceramic substrate 1 to the outside. It is deposited.

  Further, when the wiring layer 2 is coated with a metal having excellent corrosion resistance such as nickel and gold and good conductivity on the exposed outer surface to a thickness of 1 to 20 μm by plating, the oxidative corrosion of the wiring layer 2 is caused. Is effectively prevented, and when the light emitting element 4 is connected to the wiring layer 2 via the conductive adhesive 7, the connection can be improved. Therefore, it is preferable that the wiring layer 4 has nickel, gold, etc. deposited on its exposed outer surface to a thickness of 1 to 20 μm by plating.

  Further, the ceramic base 1 is coated with a metal reflection film 3 on the inner wall surface of the recess 1a. The metal reflecting film 3 acts to reflect the light emitted from the light emitting element 4 accommodated in the concave portion 1a within the concave portion 1a and to substantially increase the light emission luminance of the light emitting element 4. Accordingly, when the light emitting element 4 is used as a light source for an electric display board, for example, the light emitted from the light emitting element 4 is bright and bright, and the characters and images displayed on the electric display board can be brightened.

  The metal reflective film 3 is preferably made of gold, silver, nickel or the like. For example, a metal powder metallized layer is previously deposited on the inner wall surface of the concave portion 1a of the ceramic substrate 1, and the gold is deposited on the metallized layer. Alternatively, silver, nickel, or the like is deposited by plating, or gold, silver, nickel, or the like is deposited on the inner wall surface of the recess 1a of the ceramic substrate 1 by vapor deposition, plating, or the like.

  The metal reflection film 3 is not provided on the entire inner wall surface of the recess 1a of the ceramic substrate 1, but is deposited at a distance of, for example, about 0.01 to 0.3 mm from the bottom surface of the recess 1a. As described above, since the metal reflective film 3 is deposited with a distance of about 0.01 to 0.3 mm from the bottom surface of the recess 1a, the light emitted from the light emitting element 4 is efficiently reflected by the metal reflective film 3. In addition, an electrical short circuit between the metal reflective film 3 and the wiring layer 2 on the bottom surface of the recess 1a can be effectively prevented.

  Furthermore, in the light emitting element mounting substrate of the present invention, a frame-like metallized layer 6 surrounding the recess 1a in which the light emitting element 4 is accommodated is formed on the upper surface of the ceramic substrate 1. The frame-like metallization layer 6 is made of metal powder metallization such as tungsten, molybdenum, silver, or copper. When the sealing resin 5 is filled in the recess 1a, a large amount of the sealing resin 5 is formed on the upper surface of the ceramic substrate 1. Functions as a barrier to prevent the frame-like metallization layer 6 from getting wet with the sealing resin 5 and the sealing resin 5 exceeds the frame-like metallization 6. Thus, it is possible to effectively prevent a large amount of the upper surface of the ceramic substrate 1 from getting wet.

  Therefore, according to the light emitting element mounting substrate of the present invention, the thickness and surface shape of the sealing resin 5 do not vary greatly among the respective light emitting devices, and the light emitted from the light emitting element 4 is entirely in the sealing resin layer 5. Since the light is refracted uniformly and emitted to the outside by the light emitting device, it is possible to make the characters and images displayed by the light-emitting display board using these light emitting devices extremely clear.

  Furthermore, as shown in a top view in FIG. 2, the frame-like metallized layer 6 is formed with a hollow portion 6 a that opens to the inner periphery between the inner periphery and the outer periphery. In this manner, the hollow metallized layer 6 surrounding the recess 1a in which the light emitting element 4 is accommodated is formed on the upper surface of the ceramic substrate 1 so that the hollow portion 6a that opens to the inner periphery is formed between the inner periphery and the outer periphery. When the sealing resin 5 is filled in the recess 1a, even if there is a slight excess in the amount of the sealing resin material 5 filled, the excess sealing resin 5 is Since the sealing resin 5 in the recess 1a is kept substantially constant by being accommodated in the hollow portion 6a provided in the frame-shaped metallized layer 6, the thickness and surface shape of the sealing resin 5 in the recess 1a are kept constant. It can be made extremely accurate and constant. Therefore, it is preferable that the frame-like metallized layer 6 is provided with a hollow portion 6a that opens to the inner periphery between the inner periphery and the outer periphery.

  When the width W of the opening of the hollow portion 6a formed between the inner periphery and the outer periphery of the frame-shaped metallized layer 6 is less than 0.5 mm, the sealing resin 5 is filled in the recess 1a. In addition, excess sealing resin 5 tends to be difficult to flow into the hollow portion 6a. On the other hand, if the thickness exceeds 2.0 mm, a large amount of sealing resin 5 easily flows out into the hollow portion 5 and is contained in the recess 1. There is a risk that the sealing resin 5 is insufficient. Therefore, the width W of the opening of the hollow portion 6a is preferably in the range of 0.5 to 2.0 mm.

  In addition, when the width D of the hollow portion 6a is less than 0.05 mm, the excess sealing resin 5 can be sufficiently accommodated in the hollow portion 6a when the concave portion 1a is filled with the sealing resin 5. On the other hand, if the thickness exceeds 1.0 mm, it is necessary to increase the area of the upper surface of the ceramic substrate 1 in order to provide the hollow portion 6a having such a width, and the ceramic substrate 1 becomes larger. End up. Therefore, the width D of the hollow portion 6a is preferably in the range of 0.05 to 1.0 mm.

In addition, when the length L of the hollow portion 6a is less than 0.3 mm, the excess sealing resin 5 can be sufficiently accommodated in the hollow portion 6a when the concave portion 1a is filled with the sealing resin 5. There is a risk that it will not be possible. Therefore, the length of the hollow portion 6a is preferably 0.3 mm or more.

  The frame-like metallized layer 6 employs a conventionally well-known screen printing method on a ceramic green sheet for the ceramic substrate 1 using a metal paste obtained by adding an appropriate organic binder and solvent to a metal powder such as tungsten. Then, it is printed and applied, and is fired together with a laminate of ceramic green sheets for the ceramic substrate 1 so as to be deposited on the upper surface of the ceramic substrate 1 so as to surround the recess 1a.

  The frame-like metallized layer 6 is effectively prevented from oxidative corrosion of the frame-like metallized layer 6 by depositing a plated metal layer of nickel, gold or the like on the exposed surface to a thickness of 1 to 20 μm. The wettability between the frame-like metallized layer 6 and the sealing resin 5 can be made extremely poor. Therefore, it is preferable to deposit a plated metal layer such as nickel or gold on the exposed surface of the frame-shaped metallized layer 6 to a thickness of 1 to 20 μm.

  Thus, according to the light emitting element mounting substrate of the present invention, the light emitting element 4 is disposed on the bottom surface of the recess 1a of the ceramic substrate 1, and the electrode is electrically connected to the wiring layer 2 via the conductive adhesive 7. Then, after filling the concave portion 1a with a transparent sealing resin material 5 such as an epoxy resin so that the surface thereof is flat and sealing the light emitting element 4 in an airtight manner as a product. It becomes a light emitting device.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

For example, in the embodiment of the present invention, the hollow portion 7 is formed at one place on the upper surface of the ceramic substrate 1. However, by forming two or more portions, the sealing resin material 5 on the upper surface of the ceramic substrate 1 is formed. You may make it easy to manage parallelism and flatness.

It is sectional drawing which shows an example of embodiment of the light emitting element mounting substrate of this invention. It is a top view of the light emitting element mounting substrate shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ceramic base | substrate 1a ... Concave part 4 ... Light emitting element 6 ... Frame-shaped metallized layer 6a ... Hollow-out part

Claims (3)

A light-emitting element mounting substrate having a concave portion in which a light-emitting element is accommodated on an upper surface of a ceramic substrate,
A frame-like layer including a metallized layer is deposited on the upper surface of the ceramic substrate so as to surround the recess, and a reflective film including a metallized layer is deposited on the inner wall surface of the recess. A substrate for mounting a light-emitting element.   2. The light emitting element mounting substrate according to claim 1, wherein the frame-shaped metallized layer has a hollow portion that opens to the inner peripheral side between an inner periphery and an outer periphery thereof. The light emitting element mounting substrate according to claim 1 or 2,
A light emitting element placed in the recess of the light emitting element mounting substrate;
A light emitting device comprising: a sealing resin filled in the recess.

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