JPWO2012133899A1 - Light emitting element substrate and light emitting device - Google Patents

Abstract

A light emitting device substrate that has sufficient heat dissipation and can suppress a decrease in light emission luminance over time due to discoloration of the sealing layer and the like, and a light emitting device excellent in long-term use stability using the same I will provide a. A substrate composed of a sintered body of a glass ceramic composition containing glass powder and ceramic powder, a part of which has a mounting surface to be a mounting part on which a light emitting element is mounted, and a metal mainly composed of silver embedded in the base A second glass powder formed on the mounting surface excluding the layer, the element connection terminal formed on the mounting surface electrically connected to the electrode of the light emitting element, and the mounting portion and the element connection terminal forming portion And a coating layer made of a sintered body of a coating composition mainly comprising: a substrate for a light emitting device, wherein the concentration of silver contained in the glass of the coating layer is 0.3% by mass in terms of Ag2O. The substrate for light emitting elements which is the following.

Description

  The present invention relates to a light emitting element substrate and a light emitting device using the same.

  2. Description of the Related Art In recent years, light emitting devices using light emitting diode elements have been used as lighting, various displays, backlights for large liquid crystal TVs, and the like with the increase in brightness and whiteness of light emitting diode (LED) elements. However, the amount of heat generation increases as the brightness of the light emitting diode element increases, and the temperature rises excessively, so that sufficient light emission brightness cannot always be obtained. Therefore, there is a demand for a substrate for a light-emitting element for mounting a light-emitting element such as a light-emitting diode element, which can quickly dissipate heat generated from the light-emitting element and obtain sufficient light emission luminance.

  Conventionally, a substrate for a light-emitting element for mounting such a light-emitting element has a structure in which a wiring conductor layer for connecting the light-emitting element and an external electrode is disposed on or inside an insulating substrate such as a ceramic substrate. Is often used. Further, in such a light emitting device, generally, a sealing layer made of a silicone resin or an epoxy resin is provided to protect the light emitting element and the wiring conductor layer mounted on the light emitting element substrate. A light emitting device having a structure in which white light emission is obtained in combination with a light emitting element by dispersing and blending a fluorescent material in a sealing layer has been put into practical use.

  Recently, as such a ceramic substrate for a light emitting element, low temperature firing, low dielectric constant, and high electrical conductivity copper and silver wiring can be fired simultaneously, so low temperature cofired ceramics (Low Temperature). Co-fired ceramics (hereinafter referred to as LTCC) has been proposed.

  The LTCC substrate is made of, for example, glass and alumina powder, and has a large difference in refractive index, a large number of these interfaces, and a thickness that is larger than the wavelength to be used, so that a high reflectance can be obtained. Thereby, the light from a light emitting element can be used efficiently, and the calorific value can be reduced as a result. Moreover, since it consists of an inorganic oxide with little deterioration by a light source, the stable color tone can be maintained over a long period of time.

  However, since the LTCC substrate does not necessarily have a high thermal conductivity, the LTCC substrate is made of, for example, a high thermal conductive metal material such as copper or silver in order to quickly dissipate the heat generated as the light emitting element increases in brightness. A thermal radiation layer such as a thermal via is embedded in a substrate to reduce thermal resistance (see Patent Document 1). Many LTCC substrates have a structure in which a wiring conductor layer is disposed inside the substrate for the purpose of protecting the constituent metals from oxidation and corrosion.

  However, when silver or a silver alloy is used as a constituent metal of a metal layer such as a wiring conductor layer or a thermal via that is wired in an inner layer in such an LTCC substrate, a light emitting element is mounted on the LTCC substrate and a silicone resin or the like is sealed. When sealed with a stop layer, color development such as brown or yellow occurs at the interface between the LTCC substrate and the sealing layer such as silicone resin, and the color tone becomes darker after long-term use, reducing the brightness as a light emitting device. There was a problem to do.

Japanese Unexamined Patent Publication No. 2006-41230

  The present invention has been made in order to solve the above-described problems, and has a sufficient heat dissipation when used as a light emitting device, and suppresses a decrease in light emission luminance over time due to discoloration of the sealing layer. An object of the present invention is to provide a light emitting element substrate. Another object of the present invention is to provide a light-emitting device that has sufficient heat dissipation and excellent long-term use stability in which a decrease in light emission luminance over time due to discoloration of a sealing layer is suppressed.

The substrate for a light emitting device of the present invention comprises a sintered body of a glass ceramic composition containing a first glass powder and a first ceramic powder, and a mounting surface that is a mounting portion on which a light emitting device is mounted. A base body having silver, a metal layer mainly composed of silver embedded in the base body, an element connection terminal formed on the mounting surface electrically connected to an electrode of the light emitting element, the mounting portion and its vicinity, And a coating layer formed on the mounting surface excluding the element connection terminal forming portion and the vicinity thereof and made of a sintered body of a coating composition mainly composed of the second glass powder. a is, wherein the concentration of the silver contained in the glass of the coating layer is not more than 0.3 mass% in terms of Ag 2 _O.

In the substrate for light emitting device of the present invention, the second glass powder is expressed in terms of mol% in terms of oxide, SiO ₂ is 70 to 84%, B ₂ O ₃ is 10 to 25%, and Al ₂ O ₃ is 0. 5%, at least 0-5% one in total selected from the group consisting of Na ₂ O and _{K 2} O, the MgO 0%, CaO, at least one selected from the group consisting of SrO and BaO It is preferable that the total content of SiO ₂ and Al ₂ O ₃ is 70 to 84% in terms of mol% in terms of oxide in the glass powder.

  In the substrate for light emitting device of the present invention, the coating composition preferably contains a second ceramic powder. Specifically, a ceramic powder substantially free of alumina powder as the second ceramic powder is contained in the coating composition in an amount of 1 to 20% by mass, and alumina as the second ceramic powder. The aspect in which the content of the alumina powder is 1 to 10% by mass in the coating composition is preferably a ceramic powder mainly containing powder.

In the light emitting device substrate of the present invention, for the sintered body of the glass ceramic composition constituting the substrate, the first ceramic powder comprises an alumina powder and a ceramic powder having a higher refractive index than alumina. The ceramic powder is preferably contained.
In the light emitting element substrate of the present invention, the metal layer mainly composed of silver is parallel to the mounting surface, and a distance from the mounting surface to the upper surface of the metal layer is 50 to 150 μm. Thus, it is preferably embedded in the base.
In the light emitting device substrate of the present invention, the coating layer preferably has a thickness of 10 to 50 μm.

The light emitting device of the present invention includes the light emitting element substrate of the present invention and a light emitting element mounted on a mounting portion of the light emitting element substrate. In the light emitting device of the present invention, it is preferable that a part or all of the surfaces of the substrate and the coating layer are sealed with a silicone resin containing a platinum catalyst.
The term “to” indicating the numerical range described above is used to mean that the numerical values described before and after that are used as the lower limit value and the upper limit value unless otherwise specified, and hereinafter “to” is the same in the specification. Used with meaning.

  According to the substrate for a light-emitting element of the present invention, when this is used as a light-emitting device, it has sufficient heat dissipation and can suppress a decrease in light emission luminance over time due to discoloration of the sealing layer. In addition, the light-emitting device of the present invention has sufficient heat dissipation and suppresses a decrease in light emission luminance over time due to discoloration of the sealing layer, and is excellent in long-term use stability.

It is drawing which shows one Embodiment of the board | substrate for light emitting elements of this invention, (a) is the top view, (b) is the sectional drawing. It is drawing which shows one Embodiment of the light-emitting device of this invention, (a) is the top view, (b) is the sectional drawing.

  Hereinafter, although an embodiment of the present invention is described, the present invention is not limited to this.

The substrate for a light emitting device of the present invention comprises a sintered body of a glass ceramic composition containing a first glass powder and a first ceramic powder, and a mounting surface that is a mounting portion on which a light emitting device is mounted. A base body having silver, a metal layer mainly composed of silver embedded in the base body, an element connection terminal formed on the mounting surface electrically connected to an electrode of the light emitting element, the mounting portion and its vicinity, And a coating layer formed on the mounting surface excluding the element connection terminal forming portion and the vicinity thereof and made of a sintered body of a coating composition mainly composed of the second glass powder. a is, wherein the concentration of the silver contained in the glass of the coating layer is not more than 0.3 mass% in terms of Ag 2 _O. As the glass ceramic composition containing the first glass powder and the first ceramic powder, low temperature firing, low dielectric constant, and high electrical conductivity copper and silver wiring can be fired simultaneously, Low temperature co-fired ceramics (LTCC) are preferred.

In the light emitting device substrate of the present invention, the metal layer mainly composed of silver or silver alloy embedded in the base body made of LTCC mainly has a heat radiation function for reducing thermal resistance.
In a light emitting device in which a light emitting element is mounted on a conventional LTCC substrate in which a metal layer made of silver or a silver alloy is wired as an inner layer and sealed with a silicone resin or the like, the LTCC substrate and the silicone resin or the like are sealed. The brown or yellow color developed at the interface with the layer is considered to be caused by a phenomenon called silver color.
For example, an LTCC substrate in which a metal layer made of silver or a silver alloy is wired as an inner layer has a paste layer of silver or a silver alloy in a green sheet produced using a glass ceramic composition containing alumina powder as a ceramic powder. After being formed by screen printing or the like, it is manufactured by simultaneous firing.

Here, first, in this co-firing process, silver ions (Ag ⁺ ) diffuse from the silver layer or silver alloy layer to the glass component in the LTCC, and the silver ions are localized around the surface of the alumina powder. A high concentration silver ion layer is formed. It is considered that a part of the silver ion layer localized on the surface of the alumina powder formed thereby is exposed on the surface of the LTCC substrate.
Further, when a light emitting element is mounted on the LTCC substrate thus obtained and sealed with a sealing layer such as a silicone resin, silver ions (Ag ⁺ ) present on the surface of the LTCC substrate are transferred to the sealing layer. When it comes into contact with the contained platinum catalyst or the like, it is reduced to Ag ⁰ and agglomerates to form colloidal particles and develop color. This is considered to cause discoloration such as brown or yellow at the interface between the LTCC substrate and the sealing layer such as silicone resin.

Therefore, in the substrate for a light emitting device of the present invention, the silver ions present on the surface of the LTCC substrate are not allowed to reach a sealing layer such as a silicone resin containing a component having a function of reducing the silver ions during sintering. A coating layer composed of a sintered body of a coating composition having a low silver ion diffusibility from the surface of the LTCC substrate into the constituent components, that is, a sintered body of a coating composition mainly composed of the second glass powder, The resulting coating layer is coated with a coating layer in which the concentration of silver contained in the glass is 0.3% by mass or less in terms of Ag ₂ O. In the substrate for a light emitting device of the present invention, the constituent component of the coating layer is mainly glass, so that the reflectivity of the LTCC substrate is hardly hindered.

Here, the coating layer according to the present invention is composed of a sintered body of the coating composition mainly composed of the second glass powder. When the coating composition is composed of only the second glass powder, the coating layer is coated. The layer is composed only of glass made of a sintered body of the second glass powder. When the coating composition contains, for example, the second ceramic powder in addition to the second glass powder, the second ceramic powder or the like is dispersed in the glass obtained by sintering the second glass powder. It becomes composition. In the present invention, the glass of the coating layer refers only to a glass portion formed by sintering the second glass powder, and when the second ceramic powder or the like is included, it is a portion excluding the ceramic powder component. is there. The concentration of silver is a content contained in the glass is the concentration expressed in mass% in terms of the concentration of Ag 2 _O.

Hereinafter, in the present specification, the concentration of silver converted to the concentration of Ag ₂ O is simply referred to as “silver concentration” as necessary. Further, in this specification, the silver concentration in the glass is determined by electron beam microanalysis of the glass of the coating layer after firing on the LTCC substrate in which a metal layer mainly composed of silver is wired as an inner layer, which becomes a light emitting element substrate. The value measured using an apparatus (EPMA: Electron Probe Micro Analyzer). Since the silver concentration in the glass of the coating layer does not change with time after firing, the timing of measurement is not limited as long as it is after firing. Further, it has been confirmed that the diffusion of silver ions into the glass is performed uniformly if the thickness is 50 μm or less, which is assumed as the thickness of the coating layer, and localizes silver ions such as alumina powder. Even when the component is present in the glass, the component itself is uniformly dispersed in the glass. Therefore, a predetermined size of the glass portion of the coating layer by the electron beam microanalyzer, for example 0.3 μm ³ or more By measuring the silver concentration in an arbitrary analysis region, the silver concentration of the entire coating layer can be obtained. Although the silver concentration of the entire coating layer may be measured using the electron beam microanalyzer, measurement of the silver concentration of the entire coating layer is not always essential in the present invention.

  In the present invention, the structure of the substrate for the light emitting element is the above structure, so that when this is used as a light emitting device, it has sufficient heat dissipation and the emission luminance decreases with time due to discoloration of the sealing layer. Can be suppressed.

Hereinafter, an embodiment of a substrate for a light emitting device of the present invention will be described with reference to the drawings. In this embodiment, twelve light emitting elements of a type in which a light emitting element having a pair of electrodes on the back surface is mounted by metal connection such as gold tin eutectic solder is mounted on a pair of element connecting terminals on a substrate. Although an example of a substrate for a light emitting element is shown, the present invention is not limited to this, and a light emitting element of a type using a method such as connection by bump or flip chip bonding may be used.
FIG. 1A is a plan view showing an embodiment of a light emitting device substrate of the present invention, and FIG.

  The light emitting element substrate 1 has a substantially flat base 2 that is mainly composed of the light emitting element substrate 1 and has a substantially square shape when viewed from above. The substrate 2 is made of a sintered body of a glass ceramic composition containing the first glass powder and the first ceramic powder, and the upper surface on which the light emitting element is mounted is used as the mounting surface 21 when the light emitting element substrate is used. Have. In this example, the opposite surface is referred to as a non-mounting surface 23. The shape, thickness, size, etc. of the substrate are not particularly limited, and can be the same as those usually used as a substrate for a light emitting device. That is, in the present invention, the above-mentioned first glass powder refers to a glass powder contained in a glass ceramic composition that is a material of the substrate 2, and the first ceramic powder refers to a glass that is a material of the substrate 2. The ceramic powder contained in a ceramic composition is said.

  In this specification, the “substantially flat substrate” means a substrate having a flat surface at a level at which the upper and lower main surfaces, that is, the mounting surface and the non-mounting surface can be recognized as a flat plate shape on the visual level. Say. Similarly, the abbreviations indicate levels that can be recognized as such on the visual level unless otherwise specified.

  The light emitting element substrate 1 further includes a frame 3 joined to the peripheral portion of the base mounting surface 21 so as to form a cavity having a bottom surface 24 that is a substantially circular portion at the center of the mounting surface 21 of the base 2. . Note that the side surface of the cavity is formed by the inner wall surface of the frame 3. In the substrate 1 for light emitting elements, a total of four light emitting elements are mounted in a substantially annular shape such as a square shape from the center of the cavity bottom surface 24 and eight light emitting elements are mounted in a substantially annular shape such as an octagonal shape on the outer side. There are 12 mounting portions 22.

  The base body 2 preferably has a bending strength of, for example, 250 MPa or more from the viewpoint of suppressing damage or the like during mounting of the light emitting element and subsequent use. The substrate 2 preferably has diffuse reflectivity from the viewpoint of further improving the light extraction efficiency when it is used as a light emitting device, and the degree of diffuse reflectivity can provide light extraction efficiency equivalent to a silver reflective film. Is preferred. A haze value measured by JIS K 7105 is used as an index for evaluating diffuse reflectance. The value is preferably 95% or more, and more preferably 98% or more.

  The raw material composition, sintering conditions, and the like of the sintered body of the glass ceramic composition including the first glass powder and the first ceramic powder constituting the substrate 2 will be described in the method for manufacturing a light emitting element substrate described later. . Further, the material constituting the frame 3 is preferably the same as the LTCC material constituting the base 2 in consideration of the adhesion to the base 2.

  On the bottom surface 24 of the cavity formed by the base 2 and the frame 3, that is, on the mounting surface 21 of the base 2, a pair of electrodes and gold-tin solder, etc. A pair of element connection terminals 4 is formed in each of the twelve mounting portions 22 so that metal connection is possible. The non-mounting surface 23 of the base 2 is provided with a pair of external connection terminals 5 serving as an anode and a cathode electrically connected to an external circuit. Here, twelve anodes and cathodes on the bottom surface 24 of the cavity are formed on the non-mounting surface 23 so as not to be short-circuited in the middle by using connection vias and wiring circuits embedded in the base 2 by a normal method. The pair of anodes and cathodes are electrically connected to each other.

  Hereinafter, the electrical connection from the element connection terminal 4 on the mounting surface 21 to the external connection terminal 5 on the non-mounting surface 23 will be described with reference to a cross-sectional view shown in FIG. The cross-sectional view of FIG. 1B is a cross-sectional view including one mounting portion 22 of the twelve mounting portions 22 and a pair of element connection terminals 4 formed in the mounting portion. In the substrate for a light emitting device of the present embodiment, the base 2 has a metal layer 6 mainly composed of silver parallel to the mounting surface 21 in the inside thereof as described later. For example, the base upper layer 2b and the base lower layer 2a are manufactured. It has the structure laminated | stacked in the process. The upper surface of the substrate upper layer 2 b is the mounting surface 21, and the lower surface of the substrate lower layer 2 a is the non-mounting surface 23.

  Here, the pair of element connection terminals 4 formed on the mounting surface 21 are electrically connected to a pair of connection vias 8b provided so as to penetrate the base body upper layer 2b. The connection via 8b is connected to each region of the metal layer 6 divided in the cross section shown in FIG. 1B, and the connection via 8a penetrates the base lower layer 2a from each region of the metal layer 6. Each of them is connected to a pair of external connection terminals 5 formed on the lower surface thereof, that is, the non-mounting surface 23. As will be described later, the metal layer 6 functions as a heat dissipation layer, but also plays a role as a wiring circuit in the present embodiment. Hereinafter, the connection vias 8a and 8b are collectively referred to as a connection via 8. The metal layer 6 is also referred to as a wiring circuit 6. The connection from each pair of element connection terminals 4 formed in the other eleven mounting portions 22 to the pair of external connection terminals 5 on the non-mounting surface is not shown in FIG. 1B. Same as shown.

  The element connection terminal 4, the external connection terminal 5, and the connection via 8 and the wiring circuit 6 embedded in the base 2 are connected to the wiring circuit 6 and the connection via embedded in the element connection terminal 4 → the base 2 from the light emitting element. As long as the anode and the cathode are electrically connected without short-circuiting from 8 → external connection terminal 5 → external circuit, the position and shape of the arrangement are not limited to those shown in FIG. It can be adjusted as appropriate. In this specification, one pair of a pair of electrodes and a pair of terminals means a pair composed of an anode and a cathode.

  The constituent materials of these element connection terminals 4, external connection terminals 5, and connection vias 8 and wiring circuits 6 embedded in the substrate 2 (hereinafter sometimes collectively referred to as “wiring conductors”) are usually light emitting. Any material can be used without particular limitation as long as it is the same constituent material as the wiring conductor used in the element substrate. Specific examples of the constituent material of these wiring conductors include metal materials mainly composed of copper, silver, gold and the like. Among such metal materials, a metal material mainly composed of silver is preferably used. Specifically, a metal material composed of silver, a metal material composed of silver and platinum, or a metal material composed of silver and palladium. The wiring circuit 6 will be described in detail in the explanation part of the metal layer 6.

  In addition, in the element connection terminal 4 and the external connection terminal 5, on the metal layer which consists of the desired metal material which comprises these terminals, this layer is protected from oxidation and sulfurization, and the electroconductive protective layer which has conductivity ( (Not shown) is preferably formed so as to cover the whole including its end edges. Here, the thickness of the metal layer is preferably 5 to 15 μm. The conductive protective layer is not particularly limited as long as it is made of a conductive material having a function of protecting the metal layer. Specific examples include a conductive protective layer made of nickel plating, chrome plating, silver plating, nickel / silver plating, gold plating, nickel / gold plating, or the like.

  In the present invention, among these, as the conductive protective layer for covering and protecting the element connection terminal 4 and the external connection terminal 5, for example, the element connection terminal 4 includes solder, gold, gold- In view of obtaining good metal connection with a bump electrode such as tin eutectic, it is preferable to use a metal plating layer having a gold plating layer as at least the outermost layer. The conductive protective layer may be formed only of a gold plating layer, but is more preferably formed as a laminated structure of a nickel / gold plating layer in which gold plating is performed on nickel plating. In this case, the thickness of the conductive protective layer is preferably 2 to 20 μm for the nickel plating layer and 0.1 to 1.0 μm for the gold plating layer.

  The substrate for light emitting element 1 has a metal layer 6 mainly composed of silver embedded in a surface parallel to the mounting surface 21 in the base 2. In the present embodiment, the metal layer 6 is provided so as to function as the wiring circuit in addition to the function as a heat dissipation layer for reducing thermal resistance. Therefore, the metal layer 6 functions as an anode and a cathode that are electrically connected from the mounting surface 21 to the non-mounting surface 23 on the parallel surfaces. Therefore, it is preferable that the metal layer 6a is provided so as not to be short-circuited and to secure as large an area as possible.

However, usually, the edge of the metal layer 6 on the surface parallel to the mounting surface 21 on which the metal layer 6 is formed reaches the side surface of the substrate 2 in order to protect the metal layer 6 from oxidation, corrosion, and the like. In order to avoid this, it is preferable that the distance L between the edge of the metal layer 6 and the side surface of the substrate is 50 μm or more, more preferably 75 μm or more. In addition, upper and lower substrate constituent members (that is, the substrate upper layer 2b and the substrate lower layer 2a. Hereinafter, the substrate upper layer 2b and the substrate lower layer 2a are also referred to as a substrate component member) having the formation surface of the metal layer 6 as a boundary. The formation area of the metal layer 6 is adjusted so that the substrate 2 is sufficiently adhered and manufactured.
When the metal layer 6 is provided independently of a wiring conductor such as a wiring circuit, the distance between the edge of the metal layer 6 and the edge of the wiring conductor is 100 μm or more in order to prevent a short circuit or the like. More preferably, it is formed to be 150 μm or more. Note that the upper limit of the distance L is determined by the size, specification, shape, and the like of the light emitting device.

The material constituting the metal layer 6 is not particularly limited as long as it is a material having thermal conductivity mainly composed of silver. The metal material mainly composed of silver refers to a material having a silver content of more than 50% by mass with respect to the total amount of the metal material. Specifically, the metal material composed of simple silver or silver at a ratio of 95% by mass or more. A metal material composed of silver and platinum or silver and palladium is preferably included. Specific examples of the metal material composed of silver and platinum or silver and palladium include metal materials in which the ratio of platinum or palladium to the total amount of the metal material is 5% by mass or less.
Here, in this specification, “mainly ...” means, for example, “the B composition mainly containing the component A”, and the A component is 50% by mass with respect to the total amount of the B composition. The relationship which contains exceeding is shown.

  Moreover, about the film thickness of the metal layer 6, 8-50 micrometers is preferable, 10-20 micrometers is more preferable, and 13-16 micrometers is especially preferable. If the thickness of the metal layer 6 is less than 8 μm, sufficient heat dissipation may not be obtained, and if it exceeds 50 μm, it is economically disadvantageous and deformation due to a difference in thermal expansion from the substrate body may occur during the manufacturing process. There is.

  In order to obtain sufficient heat dissipation, it is preferable that the upper surface of the metal layer 6, that is, the surface on which the light emitting element is mounted, has surface flatness that is flat. Specifically, the surface flatness is 0.15 μm or less as the surface roughness Ra at least in a portion where the light emitting element is mounted from the viewpoint of ease of manufacturing while ensuring sufficient heat dissipation. Preferably, it is 0.1 μm or less. The surface roughness Ra is the arithmetic average roughness Ra, and the value of the arithmetic average roughness Ra is represented by 3 “Definition and display of defined arithmetic average roughness” of JIS: B0601 (1994). Is done.

  Although the distance from the mounting surface 21 of the base 2 to the upper surface of the metal layer 6 depends on the design of the light emitting device, it is laminated on and under the metal layer 6 and the metal layer 6 while ensuring sufficient heat dissipation. In view of deformation due to a difference in thermal expansion from the base member constituting the substrate, it is preferably 50 to 150 μm, more preferably 80 to 120 μm. Further, when the metal layer 6 mainly composed of silver is disposed at such a position of the substrate so as to be parallel to the mounting surface 21 of the base body 2, the occurrence of silver coloring of the present invention can be suppressed and the light emitting device. In particular, the effect of suppressing the temporal decrease in the light emission luminance is remarkable.

  In the present embodiment, an example of the metal layer 6 formed in a direction parallel to the mounting surface 21 of the base body 2 is shown as a metal layer mainly composed of silver embedded in the base body in order to ensure heat dissipation. However, the silver-based metal layer embedded in the base body may be a thermal via embedded in the base body in a direction perpendicular to the mounting surface of the base body in order to reduce thermal resistance. For example, the thermal via has a columnar shape smaller than the mounting portion, and a plurality of thermal vias may be provided directly below the mounting portion. When the thermal via is provided, it can be provided from the non-mounting surface to the vicinity of the mounting surface so as not to reach the mounting surface of the base as necessary. With such an arrangement, the flatness of the mounting surface, particularly the mounting portion, can be improved, the thermal resistance can be reduced, and the inclination when the light emitting element is mounted can be suppressed. In this case, the wiring circuit is usually provided separately from the metal layer 6 having the above-described configuration.

Further, when importance is attached to the reduction of thermal resistance, the thermal via can be provided so as to penetrate from the mounting surface to the non-mounting surface of the substrate. As described above, a part of the metal layer mainly composed of silver embedded in the base may reach the constituent surface of the base, in this case, the mounting surface or the non-mounting surface. Here, the term “substrate constituent surface” is used as a general term for a mounting surface, a non-mounting surface, and a side surface of the substrate.
The light emitting element substrate of the present invention has sufficient heat dissipation by disposing the metal layer mainly composed of silver in the base body made of LTCC as described above.

The light emitting element substrate 1 includes the entire surface of the bottom surface 24 of the cavity excluding the 12 light emitting element mounting portions 22 formed on the mounting surface 21 and the vicinity thereof, and the interface between the base 2 and the frame 3. The coating layer 7 is formed in such a manner that the edge reaches an area near the outer periphery of the bottom surface of the cavity. The coating layer 7 is made of a sintered body of a coating composition mainly composed of the second glass powder, and the concentration of silver contained in the glass of the coating layer 7 is 0.3% by mass in terms of Ag ₂ O. It is as follows.
In this case, the width M of the coating layer 7 sandwiched between the base 2 and the frame 3 is preferably about 100 μm. If the coating layer 7 is provided to reach the side surface of the base 2, the adhesion between the base 2 and the frame 3 may be impaired, which is not preferable. In addition, the edge of the mounting portion 22 and the edge of the coating layer 7 have a risk that the glass overlaps the electrode due to printing misalignment, and the electrode does not function as an electrode. The distance N from the edge 7 is preferably 50 μm or more, and more preferably 100 μm or more. The upper limits of the width M and the distance N described above are determined by the dimensions, specifications, shapes, etc. of the light emitting device.

  Here, in the present embodiment, the light emitting element substrate 1 is a light emitting element substrate in which the light emitting element is metal-connected to the element connection terminal 4 provided in the mounting portion 22 on the mounting surface 21. The covering layer 7 is disposed in the region excluding the mounting portion 22 and the vicinity thereof. When the present invention is applied to a light-emitting element substrate on which a light-emitting element is mounted by wire bonding of 1-wire type or 2-wire type, in addition to the mounting part and its vicinity, the mounting part is usually separated from the mounting surface. The coating layer is formed except for the region where the element connection terminals are disposed at one or two locations and the vicinity thereof. Also in that case, the edge of the element connection terminal and the edge of the coating layer 7 are separated by 50 μm or more because there is a risk that the glass overlaps the electrode due to printing misalignment and the electrode does not function. Preferably, 100 μm or more is more preferable. The vicinity of the mounting portion 22 refers to, for example, a region within 30 μm from the outer peripheral edge of the mounting portion, and the vicinity of the region where the element connection terminals are disposed refers to the outer periphery of the region where the element connection terminals are disposed, for example. The region within 30 μm is shown.

  In the substrate for a light emitting device of the present invention, by having the coating layer 7 having such a configuration, the base 2 made of the LTCC at the time of sintering is changed from the metal layer 6 mainly composed of silver wired in the inner layer to the LTCC base. The diffusion of silver ions reaching the surface of 2 can be substantially stagnated by this coating layer, and the amount of silver ions reaching the surface of the coating layer can be greatly reduced. Thus, in the substrate for a light-emitting element of the present invention, when this is used as a light-emitting device, silver ions generally contained in the sealing layer are reduced even when the light-emitting element is mounted and then sealed with the sealing layer. It is possible to suppress a decrease in luminance with time due to the formation of silver colloid due to the action of a catalyst and the like, and further due to silver color formation due to the aggregation.

  In the substrate for light emitting device of the present invention, as the second glass powder for forming the coating layer 7, the glass powder is formed on an LTCC substrate in which a metal layer mainly composed of silver of the configuration of the present invention is wired as an inner layer. When the coating layer is formed as a sintered body of the coating composition containing, the glass powder is not particularly limited as long as the concentration of silver contained in the glass is 0.3% by mass or less.

  The softening point (Ts) of the second glass powder is preferably 930 ° C. or lower, and more preferably 880 ° C. or lower. Usually, in order to obtain a dense sintered body by firing glass powder, the firing temperature must exceed the softening point of the glass powder. When the softening point of the second glass powder exceeds 930 ° C., the metal layer mainly composed of silver which is the inner layer wiring of the LTCC substrate which is usually co-fired with the second glass powder is excessively softened at the time of firing. The shape may not be maintained. In addition, the metal layer mainly composed of silver used in the present invention may be excessively soft when it exceeds 880 ° C. depending on its composition. Therefore, by using a second glass powder having a softening point of 930 ° C. or lower, preferably 880 ° C. or lower, without causing deformation due to excessive softening of the metal layer mainly composed of silver. The coating composition containing the same and the LTCC substrate on which the metal layer mainly composed of silver is wired in the inner layer can be fired simultaneously. On the other hand, generally, a glass powder having a low softening point tends to cause the above-mentioned silver coloring. Therefore, the softening point of the second glass powder is preferably 750 ° C. or higher.

Specifically, as such second glass powder, SiO ₂ is 70 to 84%, B ₂ O ₃ is 10 to 25%, and Al ₂ O ₃ is 0 to 5 in terms of mol% in terms of oxide. %, At least one selected from the group consisting of Na ₂ O and K ₂ O, 0-5% in total, MgO 0-10%, at least one selected from the group consisting of CaO, SrO and BaO in total A glass powder containing 0 to 5% and having a total content of SiO ₂ and Al ₂ O ₃ of 70 to 84% in terms of mol% in terms of oxide in the glass powder can be mentioned. Hereinafter, in the description of the glass composition, “%” represents an oxide conversion mol% unless otherwise specified.

  By using the glass powder having the above composition as the second glass powder, the coating composition containing this as a main component is fired simultaneously with the LTCC substrate in which the metal layer mainly composed of silver is disposed in the substrate. However, when the obtained substrate for a light-emitting element is used as a light-emitting device, the interface between the coating layer and the sealing layer made of silicone resin hardly develops color, thereby reducing the emission luminance of the light-emitting device over time. Can be suppressed.

In the glass powder, SiO ₂ serves as a glass network former and is an essential component for increasing chemical durability, particularly acid resistance. If the content of SiO ₂ is less than 70%, the acid resistance may be insufficient. On the other hand, if the SiO ₂ content exceeds 84%, the glass transition point, which is also indicated as the glass softening point or Tg, may be excessively high.

B ₂ O ₃ is an essential component that becomes a glass network former. If the content of B ₂ O ₃ is less than 10%, the softening point may become excessively high, and the glass may become unstable. On the other hand, if the content of B ₂ O ₃ exceeds 25%, it is difficult to obtain stable glass, and chemical durability may be lowered. The content of B ₂ O ₃ is preferably 12% or more.

Al ₂ O ₃ is an optional component that may be added within a range of 5% or less in order to enhance the stability and chemical durability of the glass. If the content of Al ₂ O ₃ exceeds 5%, there is a possibility that the transparency of the glass decreases. On the other hand, if the content of Al ₂ O ₃ exceeds 5%, silver coloring may occur easily.

Incidentally, the total content of SiO ₂ content and _Al 2 _{O 3} in the glass powder is 70% or more and 84 %% less. If the total content of SiO ₂ and Al ₂ O ₃ is less than 70%, chemical durability may be insufficient. On the other hand, if the total content of SiO ₂ and Al ₂ O ₃ exceeds 84%, the softening point and the glass transition point may be excessively increased.

Na ₂ O and K ₂ O are optional components that can be added within a range where the total content does not exceed 5% in order to lower the softening point and the glass transition point. When the total content of Na ₂ O and K ₂ O exceeds 5%, chemical durability, particularly acid resistance may be lowered, and electrical insulation may be lowered. On the other hand, when the total content of Na ₂ O and K ₂ O exceeds 5%, silver coloring may easily occur.
Na ₂ O and K ₂ O preferably contain at least one selected from these, and the total content of Na ₂ O and K ₂ O is preferably 0.9% or more.

  MgO is an optional component that may be added within a range not exceeding 10% in order to lower the softening point and the glass transition point and increase the stability of the glass. When the content of MgO exceeds 10%, silver coloring may easily occur. The content of MgO is preferably 8% or less.

  CaO, SrO, and BaO are optional components that may be added within a range where the total content of these does not exceed 5% in order to lower the softening point and glass transition point and increase the stability of the glass. is there. When adding these, it is sufficient to contain at least one selected from the group consisting of CaO, SrO, and BaO. If the total content of CaO, SrO, and BaO exceeds 5%, the acid resistance may decrease. On the other hand, if the total content of CaO, SrO, and BaO exceeds 5%, silver coloring may easily occur.

  In addition, the said glass powder preferably used as a 2nd glass powder is not necessarily limited to what consists only of the said component, and can contain components other than the above in the range which does not impair the effect of this invention. In this embodiment, lead oxide is not contained. When it contains components other than the above, the total content is preferably 10% or less.

The covering layer 7 has an acid resistance of preferably 100 μg / cm ² or less, more preferably 30 μg / cm ² or less, still more preferably 5 μg / cm ² or less, and particularly preferably 1 μg / cm ² or less.
When the acid resistance of the coating layer 7 exceeds 100 μg / cm ² , the glass component of the coating layer 7 is eluted in the plating solution of the metal layer 6, and the continuous operation may be hindered when manufacturing the substrate for the light emitting element. The coating layer 7 may become cloudy and the reflectivity may decrease.
The acid resistance of the coating layer 7 was evaluated by immersing it in 700 cm ³ of an oxalate buffer solution having a pH of 1.68 and a temperature of 85 ° C., and measuring the amount of mass loss after 1 hour.

Among the glass powders preferably used as the second glass powder, for example, as a material capable of increasing the reflectance of the coating layer 7, SiO ₂ is 78% to 83%, B ₂ O ₃ is 16% to 18%, Glass powder comprising 0.9% to 4% in total of at least one selected from Na ₂ O and K ₂ O, 0 to 0.5% Al ₂ O ₃ , and 0 to 0.6% CaO , "Glass Powder A").

The composition of “glass powder A” will be described below.
SiO ₂ becomes a glass network former. If the content of SiO ₂ is less than 78%, chemical durability may be reduced. On the other hand, when the content of SiO ₂ exceeds 83%, the softening point and the glass transition point may be excessively increased. The content of SiO ₂ is preferably 80% or more. Further, the content of SiO ₂ is preferably 82% or less.

B ₂ O ₃ is a glass network former. When the content of B ₂ O ₃ is less than 16%, the softening point and the glass transition point may be excessively high. On the other hand, if the content of B ₂ O ₃ exceeds 18%, it is difficult to obtain a stable glass, and chemical durability may be lowered. The content of B ₂ O ₃ is preferably 17% or less.

Al ₂ O ₃ may be added in a range of 0.5% or less in order to enhance the stability and chemical durability of the glass. When the content of Al ₂ O ₃ exceeds 0.5%, the softening point and the glass transition point may be excessively increased. If the content of Al ₂ O ₃ exceeds 0.5%, silver coloring may occur easily.

Na ₂ O and K ₂ O are added to lower the softening point and the glass transition point, and it is necessary to contain at least one of Na ₂ O and K ₂ O. When the total content of Na ₂ O and K ₂ O is less than 0.9%, the softening point and the glass transition point may be excessively high. On the other hand, when the total content of Na ₂ O and K ₂ O exceeds 4%, chemical durability, particularly acid resistance may be lowered, and electric insulation may be lowered. On the other hand, when the total content of Na ₂ O and K ₂ O exceeds 4%, silver coloring may easily occur. The total content of Na ₂ O and K ₂ O is preferably 1.0% or more, more preferably 1.5% or more. The total content of Na ₂ O and K ₂ O is preferably 3% or less, more preferably 2% or less.

  CaO may be added within a range not exceeding 0.6% in order to lower the softening point and the glass transition point and increase the stability of the glass. If the content of CaO exceeds 0.6%, the softening point and the glass transition point may be excessively lowered, and crystallization is promoted, so that transparent glass may not be obtained. On the other hand, if the CaO content exceeds 0.6%, silver coloration tends to occur.

Among the glass powders preferably used as the second glass powder, other glass powders that can increase the reflectance of the coating layer 7 include, for example, 72 to 78% of SiO _{2 and} 13 of B ₂ O _3. Glass powder (hereinafter referred to as “glass powder B”) consisting of ˜18%, at least one selected from Na ₂ O and K ₂ O being 0.9 to 4% in total and MgO being 2 to 10%. preferable.

The composition of “glass powder B” will be described below.
SiO ₂ becomes a glass network former. When the content of SiO ₂ is less than 72%, chemical durability may be lowered. On the other hand, when the content of SiO ₂ exceeds 78%, the glass softening point or glass transition point may be excessively high. The content of SiO ₂ is preferably 73% or more. Further, the content of SiO ₂ is preferably 76% or less.

B ₂ O ₃ is a glass network former. If the content of B ₂ O ₃ is less than 13%, there is a possibility that the softening point or glass transition point of the glass becomes excessively high. On the other hand, if the content of B ₂ O ₃ exceeds 18%, it is difficult to obtain a stable glass, and chemical durability may be lowered. The content of B ₂ O ₃ is preferably 17% or less.

  MgO is added to lower the softening point and glass transition point and to increase the stability of the glass. When the content of MgO is less than 2%, the softening point and the glass transition point may be excessively high, and the glass may become unstable. On the other hand, if the content of MgO exceeds 10%, silver coloring may occur easily. The content of MgO is preferably 4% or more. The content of MgO is preferably 8% or less, more preferably 6% or less.

Na ₂ O and K ₂ O are added to lower the softening point and the glass transition point, and it is necessary to contain at least one of Na ₂ O and K ₂ O. When the total content of Na ₂ O and K ₂ O is less than 0.9%, the softening point and the glass transition point may be excessively high. On the other hand, when the total content of Na ₂ O and K ₂ O exceeds 4%, chemical durability, particularly acid resistance may be lowered, and electrical insulation may be lowered. On the other hand, if the total content of Na ₂ O and K ₂ O exceeds 4%, silver coloring may easily occur. The total content of Na ₂ O and K ₂ O is preferably 1.0% or more, more preferably 1.5% or more. The total content of Na ₂ O and K ₂ O is preferably 3% or less.

  The glass powder that is preferably used as the second glass powder is not necessarily limited to the above-mentioned “glass powder A” or “glass powder B” consisting of only the respective components, and does not impair the effects of the present invention. In addition, components other than the above can be contained in both “glass powder A” and “glass powder B”. In this embodiment, lead oxide is not contained. When it contains components other than the above, the total content is preferably 10% or less.

  Further, the second glass powder is not limited to the glass powders having the above-described compositions, and glass powders having a composition different from these can be used as long as the conditions in the present invention are satisfied.

  The second glass powder used in the present invention is prepared by mixing glass raw materials so as to have the glass composition as described above, mixing them, producing glass by a melting method, and subjecting the obtained glass to dry pulverization or wet pulverization. Can be obtained by crushing. In the case of the wet pulverization method, it is preferable to use water as a solvent. The pulverization can be performed using a pulverizer such as a roll mill, a ball mill, or a jet mill.

Note that (may be referred to as follows _{D 50.) 50%} particle diameter of the second glass powder, 0.5 [mu] m or more, is preferably not more than 4 [mu] m. When the 50% particle size of the glass powder is less than 0.5 μm, the glass powder tends to aggregate, making handling difficult, and the time required for pulverization may be too long. On the other hand, if the 50% particle size of the glass powder exceeds 4 μm, the glass softening temperature may increase or the sintering may be insufficient. The adjustment of the particle diameter can be performed by classification as necessary after pulverization, for example.
In the present specification, the 50% particle size is measured using a laser diffraction / scattering particle size distribution measuring apparatus. As the laser diffraction / scattering particle size distribution measuring device, a laser diffraction / scattering particle size distribution measuring device (trade name: SALD2100) manufactured by Shimadzu Corporation was used.

  The maximum particle size of the second glass powder is preferably 20 μm or less. When the maximum particle size exceeds 20 μm, the sinterability of the glass powder is lowered, and undissolved components remain in the sintered body, which may reduce the reflectivity of the coating layer 7. The maximum particle size of the glass powder is more preferably 10 μm or less.

  In the light emitting element substrate 1 of the present invention, the coating composition whose sintered body forms the coating layer 7 is composed mainly of the second glass powder. By forming the coating layer 7 with a sintered body of the coating composition consisting only of the second glass powder, a metal layer mainly composed of silver wired in the inner layer on the base 2 made of the LTCC at the time of sintering. 6, the diffusion of silver ions reaching the surface of the LTCC substrate 2 is substantially stagnated by this coating layer, and the amount of silver ions reaching the surface of the coating layer can be greatly reduced. It is possible to suppress a decrease in light emission luminance over time due to silver coloring generated at the interface between the stop layer and the substrate.

  However, when the coating layer 7 is formed of the coating composition consisting only of the second glass powder, the coating composition, that is, the second glass has high fluidity in an unfired state, and is undulated during firing. Deformation tends to occur. Therefore, when the coating layer 7 is formed with the coating composition consisting only of the second glass powder, an uneven surface is likely to be formed on the surface of the fired body, and the flatness is lowered. In order to prevent this, in the coating composition, it is preferable to add a second ceramic powder in addition to the second glass powder as necessary.

  The second ceramic powder used in the coating composition for such purposes preferably includes a ceramic powder substantially free of alumina powder, and the content thereof is as follows in the coating composition: The aspect containing 1-20 mass% is mentioned. In such a blending amount, a ceramic powder substantially free of alumina powder as the second ceramic powder is blended with the coating composition, whereby the diffusion layer of silver ions is substantially stagnated in the resulting coating layer. It is possible to form a coating layer having a flat surface while greatly reducing the amount of silver ions reaching the surface. In addition, when the ceramic composition containing more than 20 mass% and substantially not containing alumina powder is blended in the coating composition, the coating layer 7 may be insufficiently sintered.

The behavior of silver ions in the LTCC substrate during firing is as described above, and the silver ions diffused in the glass component are localized particularly around the surface of the alumina powder to form a high concentration silver ion layer. To do. It is considered that a part of the silver ion layer localized on the surface of the alumina powder formed thereby is exposed on the surface of the LTCC substrate.
Therefore, when the second ceramic powder is blended in the coating composition for the purpose of surface flatness, a ceramic powder substantially free of alumina powder is used. The phrase “substantially free of alumina powder” means that the content of alumina powder in the ceramic powder is less than 0.1% by mass. Here, in the present specification, when a ceramic powder such as an alumina powder is displayed, a component having a content exceeding 50 mass% is used as the name of the powder as a constituent component of the powder. For example, ceramic powder containing Al ₂ O ₃ in excess of 50 mass% is referred to as alumina powder.

Here, when a ceramic powder substantially free of alumina powder is used as the second ceramic powder, among the above-mentioned alumina powders, the alumina powder containing Al ₂ O ₃ at a high content is not substantially contained. It is particularly preferred. Here, “including Al ₂ O ₃ at a high content” means that the Al ₂ O ₃ content is 95% by mass or more.

  As such a second ceramic powder that substantially does not contain alumina powder, conventionally used ceramic powder can be used without particular limitation as long as it is other than alumina powder. Specifically, for example, as long as it is at least one ceramic powder selected from the group consisting of zirconia powder, titania powder, and silica powder, it may be blended in the coating composition at the above ratio. A more preferable blending amount is 5 to 10% by mass in the coating composition. The 50% particle size of the second ceramic powder is preferably, for example, not less than 0.5 μm and not more than 4 μm.

In addition, for the purpose of imparting diffuse reflectance to the coating layer, a ceramic powder mainly containing alumina powder as the second ceramic powder can be blended with the coating composition as necessary. As content, the aspect which the content of the said alumina powder contains in 1-10 mass% in the said composition for coating | cover is mentioned. A more preferable content is such that the content of the alumina powder is 1 to 5% by mass in the coating composition.
By blending ceramic powder mainly containing alumina powder as the second ceramic powder with such a blending amount into the coating composition, the diffusion layer of silver ions is substantially stagnated in the resulting coating layer, and the coating layer surface Thus, it is possible to form a coating layer having diffuse reflectivity while greatly reducing the amount of silver ions reaching the maximum. If the alumina powder exceeds 10% by mass in the coating composition, it becomes difficult for the coating layer 7 to stagnate the diffusion of silver ions, and silver coloring occurs at the interface between the coating layer and the sealing layer. May occur.

  In this case, it is also possible to mix ceramic powder other than alumina powder in the coating composition within a range not impairing the above effects. As a compounding quantity, 5 mass% or less is mentioned as mass% of ceramic powder other than an alumina powder with respect to the total amount of an alumina powder and the other ceramic powder. Examples of the ceramic powder used in combination with the alumina powder include at least one ceramic powder selected from the group consisting of zirconia powder, titania powder, and silica powder.

  The thickness of the coating layer 7 is preferably 10 to 50 μm, and more preferably 20 to 30 μm. When the thickness of the coating layer 7 is less than 10 μm, the coating layer 7 can sufficiently diffuse the silver ions reaching the surface of the LTCC substrate 2 from the metal layer 6 mainly composed of silver wired in the inner layer. In some cases, the amount of silver ions reaching the surface of the coating layer cannot be reduced so much. As a result, silver coloration occurs at the interface between the sealing layer and the coating layer, which may cause a decrease in light emission luminance of the light emitting device with time. On the other hand, if the thickness of the coating layer 7 exceeds 50 μm, the volume of the coating layer 7 becomes excessive, and the thermal conductivity may decrease, or the reflectance of the coating portion may decrease, and the light extraction efficiency may decrease. There is.

  As mentioned above, although the embodiment in the light emitting element substrate of the present invention has been described by way of example, the light emitting element substrate of the present invention is not limited thereto. As long as it does not contradict the spirit of the present invention, the configuration can be changed as necessary.

  In addition, a method for manufacturing a light-emitting element substrate according to the present invention will be described below using the light-emitting element substrate 1 shown in FIG. 1 as an example. 1 can be manufactured by a manufacturing method including, for example, the following (A) green sheet manufacturing step, (B) paste layer forming step, (C) laminating step, and (D) firing step. . In addition, about the member used for manufacture, the same code | symbol as the member of a finished product is attached | subjected and demonstrated. For example, a ceramic base and a green sheet for a ceramic base are indicated by the same reference numeral 2, and a metal layer and a paste layer for a metal layer are indicated by the same reference numeral 6, and the others are the same.

(A) Green sheet preparation process (A) process uses the glass-ceramic composition containing the 1st glass powder and the 1st ceramic powder, The green sheet 2 for base | substrates which comprises the base | substrate of a light emitting element substrate, This is a step of producing a frame green sheet 3 constituting the frame. Specifically, the base green sheet 2 and the frame green sheet 3 are made of a glass ceramic composition containing a first glass powder and a first ceramic powder described below, and a binder, and optionally a plasticizer. Then, a slurry prepared by adding a dispersant, a solvent, etc. is formed into a sheet having a predetermined shape and film thickness such that the shape and film thickness after firing are within the above desired range by the doctor blade method or the like. And can be produced by drying. As the glass ceramic composition, a low temperature co-fired ceramic (LTCC) is particularly preferable.

  About the green sheet 2 for base | substrates, the sheet-like molded object obtained by said (A) is provided to the lamination | stacking at (C) process through (B) paste layer formation process. With respect to the green sheet 3 for a frame, a through hole is formed in the shape of the bottom surface 24 of the concave portion 4 (for example, a circle) at the center of the sheet-like molded product obtained in (A) by a normal method in this step. What was formed and obtained was subjected to lamination in step (C). The base green sheet 2 and the frame green sheet 3 are not necessarily formed of a single green sheet, and may be a laminate of a plurality of green sheets. In the present embodiment, since a metal layer mainly composed of silver parallel to the mounting surface is disposed in the substrate 2, the substrate green sheet 2 is further changed into a substrate lower layer green sheet 2a and a substrate upper layer green sheet 2b. Separately described. Note that these green sheets may also be composed of a plurality of sheets.

(Preparation of glass ceramic composition and slurry)
Although the first glass powder used for the glass ceramic composition is not necessarily limited, the glass transition point is preferably 550 ° C. or higher and 700 ° C. or lower. When the glass transition point is less than 550 ° C., degreasing may be difficult, and when it exceeds 700 ° C., the shrinkage start temperature becomes high and the dimensional accuracy may be lowered.

  Further, it is preferable that crystals are precipitated when the green sheet for a substrate is fired at 800 ° C. or higher and 930 ° C. or lower. If crystals do not precipitate, sufficient mechanical strength may not be obtained. Furthermore, the crystallization peak temperature (Tc) measured by DTA (differential thermal analysis) is preferably 880 ° C. or less. When the crystallization peak temperature (Tc) exceeds 880 ° C., the dimensional accuracy may be lowered.

The first glass powder such as this, for example, in mol% on oxide basis, of _{SiO 2 57% ~65%, B} 2 O 3 of 13-18%, 9-23% of CaO, Al ₂ O ₃ 3-8%, preferably those containing at least one of a total of 0.5% to 6% or less selected from _{K 2} O and Na ₂ O. Thereby, it becomes easy to improve the flatness of the surface of the obtained base or frame.

Here, SiO ₂ becomes a glass network former. When the content of SiO ₂ is less than 57%, it is difficult to obtain a stable glass and the chemical durability may be lowered. On the other hand, when the content of SiO ₂ exceeds 65%, the glass melting temperature and the glass transition point may be excessively increased. The content of SiO ₂ is preferably 58% or more, more preferably 59% or more, and particularly preferably 60% or more. Further, the content of SiO ₂ is preferably 64% or less, more preferably 63% or less.

B ₂ O ₃ is a glass network former. If the content of B ₂ O ₃ is less than 13%, there is a possibility that the glass melting point or the glass transition point becomes excessively high. On the other hand, when the content of B ₂ O ₃ exceeds 18%, it is difficult to obtain a stable glass, and the chemical durability may be lowered. The content of B ₂ O ₃ is preferably 14% or more, more preferably 15% or more. Further, the content of B ₂ O ₃ is preferably 17% or less, more preferably 16% or less.

Al ₂ O ₃ is added to increase the stability, chemical durability, and strength of the glass. If the content of Al ₂ O ₃ is less than 3%, the glass may become unstable. On the other hand, when the content of Al ₂ O ₃ exceeds 8%, the glass melting temperature and the glass transition point may be excessively increased. The content of Al ₂ O ₃ is preferably 4% or more, more preferably 5% or more. Further, the content of Al ₂ O ₃ is preferably 7% or less, more preferably 6% or less.

  CaO is added to increase glass stability and crystal precipitation, and to lower the glass melting temperature and glass transition point. When the content of CaO is less than 9%, the glass melting temperature may be excessively high. On the other hand, when the content of CaO exceeds 23%, the glass may become unstable. The content of CaO is preferably 12% or more, more preferably 13% or more, and particularly preferably 14% or more. Further, the content of CaO is preferably 22% or less, more preferably 21% or less, and particularly preferably 20% or less.

K ₂ O and Na ₂ O are added to lower the glass transition point. At least one of K ₂ O and Na ₂ O is added. When the total content of K ₂ O and Na ₂ O is less than 0.5%, the glass melting temperature and the glass transition point may be excessively high. On the other hand, when the total content of K ₂ O and Na ₂ O exceeds 6%, chemical durability, particularly acid resistance may be lowered, and electrical insulation may be lowered. The total content of K ₂ O and Na ₂ O is preferably 0.8% or more and 5% or less.

  In addition, the said glass powder preferably used as a 1st glass powder is not necessarily limited to what consists only of the said component, but can contain another component in the range with which various characteristics, such as a glass transition point, are satisfy | filled. When other components are contained, the total content is preferably 10% or less.

  The first glass powder used in the present invention is prepared by mixing glass raw materials so as to have the glass composition as described above, mixing them, producing glass by a melting method, and subjecting the obtained glass to a dry pulverization method or a wet pulverization method. It can be obtained by pulverizing. In the case of the wet pulverization method, it is preferable to use water as a solvent. The pulverization is performed using a pulverizer such as a roll mill, a ball mill, or a jet mill.

  The 50% particle size of the glass powder is preferably 0.5 μm or more and 2 μm or less. When the 50% particle size of the glass powder is less than 0.5 μm, the glass powder is likely to aggregate, making it difficult to handle and uniformly dispersing. On the other hand, when the 50% particle size of the glass powder exceeds 2 μm, the glass softening temperature may increase or the sintering may be insufficient. The particle size is adjusted by, for example, classification as necessary after pulverization.

  On the other hand, as the first ceramic powder, those conventionally used for the production of LTCC substrates can be used without particular limitation. For example, alumina powder, zirconia powder, or a mixture of alumina powder and zirconia powder is preferably used. In the case of producing a diffusely reflective LTCC that is particularly preferably used in the present invention, as the ceramic powder, together with alumina powder, ceramic powder having a higher refractive index than alumina (hereinafter referred to as high refractive index ceramics). It is preferred to use a powder).

  The high refractive index ceramic powder is a component for improving the reflectance of the sintered body (substrate), and includes, for example, at least one selected from the group consisting of titania powder, zirconia powder, and stabilized zirconia powder. . While the refractive index of alumina is about 1.8, the refractive index of titania is about 2.7 and the refractive index of zirconia is about 2.2, which is higher than that of alumina. . The mixing ratio of the alumina powder and the high refractive index ceramic powder is preferably in the range of 90:10 to 60:40 by mass ratio of alumina powder: high refractive index ceramic powder. The 50% particle size of the first ceramic powder is preferably 0.5 μm or more and 4 μm or less in any of the above cases.

  Such first glass powder and first ceramic powder, for example, the first glass powder is 30% by mass or more and 50% by mass or less, and the first ceramic powder is 50% by mass or more and 70% by mass or less. A glass ceramic composition is obtained by mixing and mixing as described above.

  A slurry is obtained by adding a binder and, if necessary, a plasticizer, a dispersant, a solvent and the like to the glass ceramic composition. As the binder, for example, polyvinyl butyral or acrylic resin is preferably used. As the plasticizer, for example, dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate, or the like is used. Moreover, organic solvents, such as toluene, xylene, 2-propanol, 2-butanol, are used suitably as a solvent.

(B) Paste layer forming step In the (B) step, various paste layers for simultaneous firing are formed on the substrate green sheet 2 obtained above, that is, the substrate lower layer green sheet 2a and the substrate upper layer green sheet 2b. . First, (B-1) a wiring conductor paste layer is formed on both of the substrate lower layer green sheet 2a and the substrate upper layer green sheet 2b. Next, (B-2) a metal layer paste layer mainly composed of silver is formed on the substrate lower layer green sheet 2a, and (B-3) a coating layer paste layer is formed on the substrate upper layer green sheet 2b.

(B-1) Wiring conductor paste layer forming step First, the conductor lower paste green sheet 2a and the substrate upper layer green sheet 2b are formed using a conductor paste (element connection terminal paste layer 4, external A connection terminal paste layer 5 and a connection via paste layer 8) are formed. Specifically, first, the connection via paste layer 8a and the connection via paste layer, which are finally embedded in the substrate, are respectively embedded in the substrate lower layer green sheet 2a and the substrate upper layer green sheet 2b. 8b is formed. These are internal wiring conductor paste layers formed so as to be electrically connected to the external connection terminal paste layer 5 from the element connection terminal paste layer 4 separately from the anode and the cathode without short circuit.

Next, a pair of external connection terminal paste layers 5 to be connected to the internal wiring conductor paste layer is formed on the lower surface of the substrate lower layer green sheet 2 a, that is, the surface to be the non-mounting surface 23. Further, 12 pairs of element connection terminal paste layers 4 are formed at predetermined positions on the upper surface of the substrate upper layer green sheet 2 b, that is, the surface to be the mounting surface 21.
Here, in the present embodiment, as described in (B-2) below, the wiring layer paste layer that is also used as the metal layer paste layer 6 is formed on the upper surface of the substrate lower layer green sheet 2a. If necessary, the substrate upper layer green sheet 2b may be composed of two green sheets, and another wiring circuit paste layer may be formed between the two green sheets.

  As a conductor paste used for forming a wiring conductor paste layer, for example, a metal powder mainly composed of copper, silver, gold, etc., added with a vehicle such as ethyl cellulose, and a solvent, etc., if necessary, is made into a paste. Can be used. As the metal powder, a metal powder composed of silver, a metal powder composed of silver and platinum, or a metal powder composed of silver and palladium is preferably used.

  As a method for forming the element connection terminal paste layer 4, the external connection terminal paste layer 5, the connection via paste layer 8, and the wiring circuit paste layer, a method of applying the above-mentioned conductor paste by a screen printing method or application And a filling method. The film thicknesses of the element connection terminal paste layer 4 and the external connection terminal paste layer 5 to be formed are adjusted so that the film thicknesses of the finally obtained element connection terminals and external connection terminals become the predetermined film thicknesses. The

(B-2) Metal layer paste layer forming step mainly composed of silver A metal layer mainly composed of silver at the predetermined position on the upper surface of the substrate lower layer green sheet 2a on which the wiring conductor paste layer is formed. The paste layer 6 is formed so that it functions as both a heat dissipation layer and a wiring circuit. The film thickness of the metal layer paste layer 6 mainly composed of silver is adjusted such that the finally obtained metal layer mainly composed of silver has the predetermined film thickness.
As the metal layer paste mainly composed of silver, a paste obtained by adding the above-described metal material containing silver as a main component to a vehicle such as ethyl cellulose and, if necessary, a solvent or the like can be used.

(B-3) Cover Layer Paste Layer Formation Step A pair of element connection terminal paste layers on the upper surface of the substrate upper layer green sheet 2b on which the wiring conductor paste layer is formed, that is, on the mounting surface 21. The coating layer paste layer 7 is formed so as to include all the regions that become the bottom surface 24 of the cavity except for the 12 mounting portions 22 including 4 and the vicinity thereof, and the edge reaches the vicinity region of the bottom surface of the cavity.
As the coating layer paste, a paste obtained by adding a vehicle such as ethyl cellulose to the above coating composition and, if necessary, a solvent or the like can be used. The film thickness of the coating layer paste layer 7 to be formed is adjusted so that the film thickness of the coating layer 7 finally obtained becomes the desired film thickness.

(C) Laminating step The substrate upper layer green sheet 2b formed with various paste layers is laminated on the substrate lower layer green sheet 2a formed with the various paste layers obtained in the step (B). The green body 3 for frames produced in the step (A) is laminated thereon to obtain the unsintered light emitting element substrate 1.

(D) Firing step After the step (C), the obtained unsintered light emitting device substrate 1 is degreased to remove a binder or the like as necessary, and the glass ceramic composition or the like is sintered. Is fired (firing temperature: 800 to 930 ° C.).

  Degreasing is preferably performed at a temperature of 500 ° C. or more and 600 ° C. or less for 1 hour or more and 10 hours or less, for example. When the degreasing temperature is less than 500 ° C. or the degreasing time is less than 1 hour, the binder or the like may not be sufficiently removed. If the degreasing temperature is about 600 ° C. and the degreasing time is about 10 hours, the binder and the like can be sufficiently removed. On the other hand, if the degreasing temperature is over 600 ° C. and the degreasing temperature is over 10 hours, productivity and the like may be lowered.

  In addition, the firing is appropriately adjusted in the temperature range of 800 ° C. to 930 ° C. in consideration of obtaining a dense structure of the base 2 and the frame 3 and maintaining the productivity and the shape of the metal layer mainly composed of silver. To do. Specifically, it is preferable to hold at a temperature of 850 ° C. or more and 900 ° C. or less for 20 minutes or more and 60 minutes or less, and particularly preferably a temperature of 860 ° C. or more and 880 ° C. or less. If the firing temperature is less than 800 ° C., the base 2 and the frame 3 may not be obtained as a dense structure. On the other hand, if the firing temperature exceeds 930 ° C., the substrate may be deformed and the productivity may decrease. In addition, the metal layer paste layer 6 containing metal powder mainly composed of silver wired in the inner layer of the base 2 may be excessively softened, so that a predetermined shape may not be maintained.

  In this way, the unsintered light emitting element substrate 1 is fired to obtain the light emitting element substrate 1. After firing, as necessary, the entire element connection terminals 4 and external connection terminals 5 are covered. The conductive protective layers used for conductor protection in the substrate for light emitting elements, such as nickel plating, chrome plating, silver plating, nickel / silver plating, gold plating, nickel / gold plating, etc. described above can be formed. Among these, a protective layer having a two-layer structure of nickel / gold plating is preferably used. For example, the nickel plating layer uses a nickel sulfamate bath and the gold plating layer uses a potassium gold cyanide bath and the like. Each can be formed by electrolytic plating.

As mentioned above, although the manufacturing method was demonstrated about an example of embodiment of the board | substrate for light emitting elements of this invention, about the formation order of the said each part etc., it can change suitably in the limit which can manufacture the board | substrate for light emitting elements.
In addition, the light emitting element substrate of the present invention includes a step of producing a multi-piece connecting substrate, which is usually used when producing a wiring substrate such as a light emitting element substrate, and dividing the same, depending on the size. You may obtain by the method of obtaining and producing each wiring board. In that case, as long as the timing of division is after the firing, it may be before the light emitting element is mounted, or after the light emitting element is mounted, before the solder fixing and mounting to the printed wiring board or the like.

  Next, the light emitting device of the present invention will be described. The light emitting device of the present invention is provided on the bottom surface 24 of the cavity of the light emitting element substrate 1 as shown in FIG. 2, for example, as a plan view (a) and a YY sectional view (b). Twelve light emitting elements 11 such as LED elements are mounted on 12 mounting portions 22 corresponding to the pair of element connection terminals 4. The light emitting element 11 has a pair of bump electrodes on the back surface, and is electrically connected to the element connection terminal 4 by metal connection via solder, gold, gold-tin eutectic or the like. The light emitting device 10 is further configured by providing a sealing layer 12 made of a mold resin so as to fill the cavity while covering the light emitting element 11 arranged as described above on the bottom surface 24 of the cavity. .

  As mold resin which comprises the sealing layer 12, since it is excellent in terms of light resistance and heat resistance, a silicone resin is preferably used. As the silicone resin, a conventionally known silicone resin used as a mold resin for a light-emitting device can be used without particular limitation. Further, by adding a catalyst such as platinum or titanium to such a mold resin, the mold resin can be quickly cured.

  In addition, the light obtained as the light-emitting device 10 can be appropriately adjusted to a desired emission color by mixing or dispersing a phosphor or the like in the sealing mold resin. That is, by mixing and dispersing the phosphor in the sealing layer, the phosphor excited by the light emitted from the light emitting element 11 emits visible light, and the visible light and the light emitted from the light emitting element 11 As a result, the light emitting device 10 can obtain a desired light emission color. The type of the phosphor is not particularly limited, and is appropriately selected according to the type of light emitted from the light emitting element and the target emission color. The arrangement of the phosphor is not limited to the method of mixing and dispersing in the sealing layer 12 as described above. For example, a phosphor layer may be provided on the sealing layer 12. is there.

According to the light emitting device 10 of the present invention, the mounting surface of the LTCC substrate excluding the mounting portion of the light emitting element and the vicinity thereof is made of the sintered body of the coating composition mainly composed of the second glass powder, and sintered. By coating with a coating layer having a silver concentration of 0.3% by mass or less converted to Ag ₂ O in the glass of the coating layer obtained by The diffusion of silver ions reaching the surface of the LTCC base 2 from the metal layer 6 mainly composed of silver wired in the inner layer is substantially stagnated by this coating layer, and the amount of silver ions reaching the surface of the coating layer is greatly reduced. it can. As a result, the formation of silver colloid due to the action of a catalyst or the like that generally reduces silver ions contained in the sealing layer and the occurrence of silver coloring due to the aggregation can be suppressed. Reduction can be suppressed.

Further, according to the light emitting device 10 of the present invention, by using the light emitting element mounting substrate 1 having a low thermal resistance in which a metal layer mainly composed of silver is embedded in the substrate as a heat dissipation layer, the light emitting element 11 is excessively disposed. Suppresses temperature rise and emits light with high brightness.
Such a light emitting device 10 of the present invention can be suitably used as a backlight for a mobile phone, a large liquid crystal display, etc., illumination for automobiles or decoration, and other light sources.

  Examples of the present invention will be described below. The present invention is not limited to these examples.

[Examples 1 to 12, Comparative Examples 1 to 3]
Test light-emitting devices of Examples 1 to 12 and Comparative Examples 1 and 2 having the same structure as the light-emitting device shown in FIG. 2 were produced by the method described below. In each of the above light emitting devices, only the constituent material of the coating layer is different. Further, as Comparative Example 3, a test light-emitting device having the same configuration as that of the light-emitting device shown in FIG. 2 was produced except that the light-emitting device shown in FIG.
In the following description, the same reference numerals are used for the members before and after firing, as described above.

<Preparation of coating layer paste>
First, various glass powders for forming a coating layer were produced. That is, a glass raw material is prepared and mixed so that each component of SiO ₂ , B ₂ O ₃ , Al ₂ O ₃ , CaO, Na ₂ O and K ₂ O becomes a glass having a composition (mol%) shown in Table 1. The raw material mixture was placed in a platinum crucible and melted at 1500-1600 ° C. for 60 minutes, and then the molten glass was poured out and cooled. The obtained glass was pulverized with an alumina ball mill for 20 to 60 hours to obtain five types of glass powders 1 to 5. In addition, ethyl alcohol was used as a solvent for pulverization.
Here, glass powders 1 to 3 are second glass powders mainly contained in the coating composition for forming a coating layer according to the present invention, and glass powders 4 and 5 are glass powders for comparative examples.

  The 50% particle size (μm) of the obtained glass powders 1 to 5 was measured using a laser diffraction / scattering particle size distribution measuring device (manufactured by Shimadzu Corporation, trade name: SALD2100). In addition, the softening point of the glass powders 1 to 5 was measured by raising the temperature to 1000 ° C. under a temperature raising rate of 10 ° C./min using a differential thermal analyzer (manufactured by Bruker AXS, trade name: TG-DTA2000). did.

The glass powders 1 to 5 obtained above and the following ceramic powders were blended in the proportions shown in Table 2 to prepare a coating composition. The notation in the column of “Glass: Ceramic” in the fourth column of Table 2 indicates the content ratio of the second glass powder and the second ceramic powder in the coating composition in wt%. For example, in Example 2, “95: 5” means 95% by weight of the second glass powder and 5% by weight of the second ceramic powder in the coating composition. The same applies to the example.
・ Alumina powder (made by Showa Denko KK, trade name: AL-45H, D ₅₀ : 2 μm)
Silica powder (Nippon Aerosil Co., Ltd., trade name: _AEROSIL380, D 50: 10nm)
・ Zirconia powder (Daiichi Rare Element Chemical Industries, trade name: HSY-3F-J, D ₅₀ : 0.6 μm)

  The coating composition obtained above and the resin component are blended at a mass ratio of 60:40, kneaded for 1 hour in a porcelain mortar, and further dispersed three times with three rolls for the coating layer. A paste was prepared. In addition, the resin component used what prepared and disperse | distributed ethyl cellulose and alpha terpineol by mass ratio 85:15.

<Production of test light-emitting device>
A substrate lower layer green sheet 2a, a substrate upper layer green sheet 2b, and a frame green sheet 3 for preparing the substrate 2 and the frame 3 of the substrate 1 for light emitting element were prepared.
First, in terms of oxide-based mol%, SiO ₂ is 60.4%, B ₂ O ₃ is 15.6%, Al ₂ O ₃ is 6%, CaO is 15%, K ₂ O is 1%, Na Glass raw materials were blended and mixed so that ₂ O became a glass having a composition of 2%, and this raw material mixture was put in a platinum crucible and melted at 1600 ° C. for 60 minutes, and then the molten glass was poured out and cooled. . This glass was pulverized for 40 hours by an alumina ball mill to produce a first glass powder. Note that ethyl alcohol was used as a solvent for grinding.

  35% by mass of this glass powder, 40% by mass of alumina powder (manufactured by Showa Denko KK, trade name: AL-45H), and zirconia powder (manufactured by Daiichi Rare Element Chemical Industries, trade name: HSY-3F-J) A glass ceramic composition was produced by blending and mixing so as to be 25% by mass. 50 g of this glass ceramic composition, 15 g of an organic solvent (toluene, xylene, 2-propanol, 2-butanol mixed at a mass ratio of 4: 2: 2: 1), plasticizer (di-2-ethylhexyl phthalate) 2.5 g of polyvinyl butyral (trade name: PVK # 3000K, manufactured by Denka Co., Ltd.) as a binder, 5 g, and 0.5 g of a dispersant (trade name: BYK180, manufactured by Big Chemie) were blended and mixed to prepare a slurry. .

  The slurry is applied on a PET film by a doctor blade method, and a plurality of dried green sheets are laminated to form a substantially flat plate-like green sheet 2a for a substrate lower layer having a thickness after firing of 0.35 mm, The substrate upper layer green sheet 2b having a substantially flat plate shape and a thickness after firing of 0.15 mm and the shape outside the frame are the same as the substrate green sheet 2, and the shape inside the frame has a diameter of 4. A green sheet 3 for a frame body having a substantially circular shape of 4 mm and a frame height of 0.5 mm was manufactured. In this embodiment, the light-emitting element substrate 1 is manufactured as a multi-piece connecting substrate, and is divided into pieces after firing, which will be described later, for a substantially square light-emitting element having an outer size of 5 mm × 5 mm. A substrate 1 was obtained. The following description will explain one section of the multi-cavity connection board that will become one light-emitting element substrate 1 after division.

  On the other hand, conductive powder (silver powder: manufactured by Daiken Chemical Industry Co., Ltd., trade name: S550) and ethyl cellulose as a vehicle are blended at a mass ratio of 85:15 so that the solid content is 85 mass%. After being dispersed in α-terpineol as a solvent, the mixture was kneaded for 1 hour in a porcelain mortar, and further dispersed three times with three rolls to produce a wiring conductor paste.

  Further, the metal layer paste mainly composed of silver is prepared by mixing silver powder (manufactured by Daiken Chemical Industry Co., Ltd., trade name: S400-2) and ethyl cellulose as a vehicle at a mass ratio of 90:10. After being dispersed in α-terpineol as a solvent so that the content becomes 87% by mass, the mixture was kneaded in a porcelain mortar for 1 hour, and further dispersed three times with a three roll.

  The upper surface of the substrate upper layer green sheet 2b has four light emitting elements in a substantially annular shape such as a square shape from the center of the bottom surface 24 of the cavity formed by the substrate 2 and the frame 3, and eight on the outer side. A total of twelve mounting portions 22 are provided so that the light emitting elements are mounted in a substantially annular shape such as an octagonal shape. Each mounting portion 22 is formed with a pair of element connection terminal paste layers 4, but before that, a hole drilling machine is used to form a diameter of 0.3 mm at a position corresponding to each element connection terminal paste layer 4. Through-holes were formed and filled with the wiring conductor paste obtained above by screen printing to form a connection via paste layer 8b. Thereafter, the 12 pairs of element connection terminal paste layers 4 were formed on the connection via paste layer 8b by the screen printing method using the wiring conductor paste.

  Twelve mounting portions 22 each including a pair of element connection terminal paste layers 4 on the upper surface of the substrate upper layer green sheet 2b on which the wiring conductor paste layer is formed, that is, the mounting surface 21, and In particular, the frame 3 is laminated in such a manner that the entire region including the bottom surface 24 of the cavity excluding the region near the mounting portion 22 from the end edge to 70 μm is included and the end edge reaches the region near the outer periphery of the bottom surface of the cavity. When this was done, the coating layer paste layer 7 was formed so that the frame 3 would have a width of 100 μm. The film thickness of the coating layer paste layer 7 was adjusted so that the film thickness of the finally obtained coating layer 7 was 20 μm.

  A metal layer paste layer 6 mainly composed of silver was formed on the upper surface of the substrate lower layer green sheet 2a by screen printing so as to function as both a heat dissipation layer and a wiring circuit. That is, the edge reaches 100 μm inside from the outer edge of the upper surface of the green sheet 2a for the lower substrate layer, and the anode and the cathode distributed to the 12 connecting via paste layers 8b are connected to each other. The metal layer paste layer 6 was formed as wide as possible in the two regions of the shape. Here, the proportion of the formation area of the metal layer paste layer 6 on the upper surface of the substrate lower layer green sheet 2a was 72%. The film thickness of the metal layer paste layer 6 was adjusted so that the finally obtained metal layer mainly composed of silver had a film thickness of 10 μm.

  Further, the connection via paste layer 8a reaching the lower surface of the base layer lower layer green sheet 2a, that is, the non-mounting surface 23, from the two regions of the metal layer paste layer 6 to be the anode and the cathode, respectively. The connection via paste layer 8b was formed. On the non-mounting surface 23 of the green sheet 2a for the substrate lower layer, a pair of external connection terminal paste layers 5 are connected to the pair of connection via paste layers 8a corresponding to the anode and cathode, as described above. It formed by the screen printing method using the paste for wiring conductors.

  The substrate upper layer green sheet 2b with various paste layers obtained above is laminated on the substrate lower layer green sheet 2a with various paste layers, and the frame green sheet 3 obtained above is laminated thereon. Thus, an unsintered multi-piece connection substrate was obtained. After putting the cut line for division so that each section of the unsintered light emitting element substrate 1 has an outer size of 5 mm × 5 mm after firing, the unfired multi-piece connection substrate obtained above is 550 ° C. Was held for 5 hours to degrease, and further held at 870 ° C. for 30 minutes and baked to produce a multi-piece connected substrate. The obtained multi-piece connection substrate was divided along the cut line to manufacture the light emitting device substrate 1.

<Evaluation>
[1] Measurement of Silver Concentration After the substrate for light emitting device 1 obtained in each of the above Examples and Comparative Examples was left for 24 hours after firing, the silver concentration in the glass in the coating layer 7 was measured using an electron beam microanalyzer. (EPMA) was used for measurement. Here, the term “in glass” refers to a region of the glass only in the coating layer 7 that does not contain other components, for example, ceramic powder such as alumina powder. The analysis region by EPMA was an arbitrarily selected region of 0.3 μm ³ . However, the same position was measured between each of the above Examples and Comparative Examples. The measurement results are shown in Table 2 as values converted to Ag ₂ O.

[2] Test of change in luminous flux over time Next, 12 light-emitting diode (LED) elements are mounted on the light-emitting element substrate 1 obtained in each of the above examples and comparative examples, as shown in FIG. A light emitting device was manufactured. That is, for each pair of element connection terminals formed on 12 mounting portions on the light emitting element substrate, one LED element having a pair of electrodes on the back surface is connected by gold-tin solder bonding, for a total of 12 LED elements were mounted. Furthermore, the mold sealing layer was formed using the sealing agent. In addition, as a sealing agent, silicone resin for sealing (made by Shin-Etsu Chemical Co., Ltd., trade name: SCR-1016A) was used. Moreover, the used sealing agent contains fluorescent substance (Chemical Optonics company make, brand name P46-Y3) in the ratio of 20 mass% with respect to the silicone resin for sealing.

About the light-emitting device 10 of each said Example and a comparative example, a rated current is applied with respect to each of the 12 LED elements 11 using a voltage / current generator (made by Advantest Corporation, brand name: R6243), and light emission is carried out. The total luminous flux (lumen) of the light obtained from the apparatus 10 was measured as the initial total luminous flux. Thereafter, the light-emitting device 10 was subjected to a test in which the light-emitting device 10 was allowed to stand for 250 hours in an environment of temperature 85 ° C. and humidity 85%, and the total luminous flux after the test was measured in the same manner as described above. (%) Was calculated.
Measurement of the total luminous flux is carried out by installing the light emitting device 10 in an integrating sphere (6 inches in diameter) and using a total luminous flux measuring device (Spectracorp, product name: SOLIDLAMBDA, CCD, LED, MONITOR, PLUS). It was. The measurement results are shown in Table 2.

As is clear from Table 2, in the light-emitting devices using the light-emitting element substrates of Examples 1 to 12, there was no silver coloring at the interface between the coating layer and the silicone resin sealing layer, and the luminance over time (total luminous flux) It was found that there was almost no reduction in the amount. This is composed of a sintered body of a coating composition mainly composed of glass powder having a specific glass composition, and the concentration of silver contained in the glass of the coating layer obtained by sintering is Since it is 0.3% by mass or less in terms of Ag ₂ O, from the metal layer 6 mainly composed of silver disposed in the inner layer to the base 2 made of LTCC at the time of sintering, the surface of the LTCC base 2 is formed. This is due to the fact that the diffusion of the silver ions that have reached the point is substantially stagnated by this coating layer, and the amount of silver ions that reaches the surface of the coating layer is greatly reduced.

  On the other hand, in the light-emitting device using the light-emitting element substrates of Comparative Examples 1 and 2, the coating layer does not have the configuration of the present invention, so that the diffusion of silver ions reaching the surface of the LTCC base 2 is performed. The amount of silver ions on the surface of the coating layer, which cannot be stagnated by the coating layer, is comparable to the amount of silver ions on the surface of the LTCC substrate on which the coating layer of Comparative Example 3 is not formed. In the light emitting device using the element substrate, it was found that the luminance was greatly reduced due to silver coloring at the interface between the coating layer and the silicone resin sealing layer.

The light-emitting element substrate of the present invention has sufficient heat dissipation, suppresses a decrease in light emission luminance over time due to discoloration of the sealing layer, etc., has excellent long-term use stability, and is useful for LED light-emitting devices It is.
The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2011-077239 filed on March 31, 2011 are incorporated herein by reference. .

DESCRIPTION OF SYMBOLS 1 ... Substrate for light emitting elements (substrate for unsintered light emitting element), 2 ... Substrate (green sheet for substrate), 3 ... Frame body (green sheet for frame body), 4 ... Element connection terminal (element connection terminal paste layer) ), 5... External electrode terminals (external connection terminal paste layer), 6... Metal layer mainly composed of silver (metal layer paste layer, wiring circuit), 7. Cover layer (cover layer paste layer), 8. 8a, 8b ... connection via (connection via paste layer), 21 ... mounting surface, 22 ... mounting portion, 23 ... non-mounting surface, 24 ... bottom surface of cavity, 11 ... light emitting element, 12 ... sealing layer, 10 ... light emission apparatus

Claims (10)

A substrate comprising a sintered body of a glass ceramic composition containing a first glass powder and a first ceramic powder, and a part of which is a mounting surface on which a light emitting element is mounted;
A metal layer mainly composed of silver embedded in the substrate;
An element connection terminal formed on the mounting surface electrically connected to the electrode of the light emitting element;
A coating layer made of a sintered body of a coating composition mainly composed of a second glass powder, formed on the mounting surface excluding the mounting portion and the vicinity thereof, and the element connection terminal forming portion and the vicinity thereof; A substrate for a light-emitting element,
Substrate for light-emitting element concentration of silver is not more than 0.3 mass% in terms of Ag 2 _O contained in the glass of the coating layer. The second glass powder is expressed in mol% in terms of oxide, SiO ₂ is 70 to 84%, B ₂ O ₃ is 10 to 25%, Al ₂ O ₃ is 0 to 5%, Na ₂ O and K. ₂ to 5% in total of at least one selected from the group consisting of 2O, 0 to 10% MgO, 0 to 5% in total including at least one selected from the group consisting of CaO, SrO and BaO, The substrate for a light-emitting element according to claim 1, wherein the total content of SiO ₂ and Al ₂ O ₃ in terms of oxide% in terms of oxide in the glass powder is 70 to 84%.   The light emitting element substrate according to claim 1, wherein the coating composition contains a second ceramic powder.   The second ceramic powder is a ceramic powder substantially free of alumina powder, and the content of the second ceramic powder in the coating composition is 1 to 20 mass in the coating composition. The substrate for a light-emitting element according to claim 3, which is%.   The second ceramic powder is a ceramic powder mainly containing an alumina powder, and the content of the alumina powder in the coating composition is 1 to 100 parts by mass with respect to 100 parts by mass of the second glass powder. The substrate for a light emitting device according to claim 3, wherein the ratio is 10 parts by mass.   The light emitting element substrate according to any one of claims 1 to 5, wherein the first ceramic powder contains an alumina powder and a ceramic powder having a higher refractive index than alumina.   The metal layer is embedded in the base so as to be parallel to the mounting surface, and a distance from the mounting surface to the upper surface of the metal layer is 50 to 150 μm. A substrate for a light-emitting element according to 1.   The thickness of the said coating layer is 10-50 micrometers, The board | substrate for light emitting elements of any one of Claims 1-7. A substrate for a light emitting device according to any one of claims 1 to 8,
A light emitting element mounted on a mounting portion of the light emitting element substrate;
A light emitting device comprising:   The light emitting device according to claim 9, wherein a part or all of the surfaces of the substrate and the coating layer are sealed with a silicone resin containing a platinum catalyst.

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