JPWO2012036132A1 - Light emitting element mounting substrate and light emitting device - Google Patents

Abstract

A substrate for mounting a light emitting device with high reflectivity of the substrate body and improved heat dissipation from the mounted light emitting device to the substrate, and excellent light extraction efficiency using such a substrate for mounting a light emitting device. Provide a high light emitting device. A substrate body made of an inorganic insulating material and having a mounting surface including a mounting portion on which a light emitting element is mounted, and a material mainly composed of glass formed on the mounting surface of the substrate body so as to cover at least the mounting portion. The overcoat layer has a thickness 3 to 20 times the surface roughness Ra of the mounting surface of the substrate body, and the surface roughness Ra of the overcoat layer Provides a light-emitting element mounting substrate having a thickness of 0.15 μm or less.

Description

  The present invention relates to a light-emitting element mounting substrate and a light-emitting device, and more particularly to a light-emitting element substrate having low thermal resistance and high heat dissipation, and a light-emitting device using the same.

  2. Description of the Related Art In recent years, light emitting devices using LED elements have been used as backlights for mobile phones and large liquid crystal TVs as light emitting diode (LED) elements become brighter and whiter. However, since the amount of heat generation increases as the brightness of the LED element increases, the substrate for mounting the light emitting element such as the LED element, instead of the resin substrate, has high heat resistance and heat generated from the light emitting element. There is a need for a material that can quickly dissipate the light and obtain sufficient light emission luminance.

  Conventionally, for example, an alumina substrate is used as a substrate for mounting a light emitting element. However, an alumina substrate has a low light reflectivity and transmits light incident on the substrate, so that a silver reflection film is formed on the substrate surface. ing. However, in this structure, it is necessary to provide a protective layer made of glass or the like on the surface of the silver reflecting film in order to prevent the reflectance from being reduced due to oxidation or sulfuration of the silver reflecting film, and the light extraction efficiency can be sufficiently increased. could not. That is, when a silver reflective film is provided on a substrate, the light extraction efficiency is higher when the area of the silver reflective film is as large as possible. It is necessary to provide a wiring conductor layer and to provide a gap for ensuring insulation between the wiring conductor layer and the silver reflecting film. However, from the gap formed for this insulation, light enters the substrate, and most of the incident light is diffusely reflected inside the substrate, making it difficult to re-radiate. There was a problem in that the reflectance was lowered.

  Further, a low temperature co-fired ceramic substrate (hereinafter referred to as LTCC substrate) is used as a light emitting element mounting substrate having a higher reflectance than a ceramic substrate such as an alumina substrate. The LTCC substrate is made of a sintered body of ceramic powder such as alumina powder and glass, and has a large refractive index difference between the glass and ceramic, and a large proportion of the interface between the two facing the light incident direction. Since the particle size of the powder is larger than the wavelength used, a high reflectance can be obtained. Therefore, the light from the light emitting element can be used efficiently, and as a result, the heat generation amount can be reduced. Moreover, since it consists of an inorganic oxide with little deterioration by a light source, a color tone is stabilized over a long period of time.

  In such an LTCC substrate, ceramic powder (for example, zirconia powder) having a refractive index higher than that of alumina is used in combination with alumina powder in order to increase light extraction efficiency without providing a reflective film such as the above-described silver reflective film. At the same time, it has been proposed to improve the reflectance of the substrate itself by increasing the content ratio of these ceramic powders as compared to a normal LTCC substrate (see, for example, Patent Document 1).

  However, since the surface roughness of such an LTCC substrate is larger than that of a normal LTCC substrate, when a light emitting element such as an LED element is mounted on the substrate surface, the contact area between the light emitting element and the substrate is reduced. There has been a problem that heat dissipation from the light emitting element to the substrate is lowered. In addition, when mounting and mounting a light emitting element on an LTCC substrate having a large surface roughness, a die bond material having a low thermal conductivity (the thermal conductivity of the silicone die bond material is equal to the gap between the substrate surface and the light emitting element) Since a thick layer of 0.1 W / m · K) is sandwiched, there is a problem that heat dissipation from the light emitting element to the substrate is further reduced.

  As for the smoothing of the ceramic substrate surface, conventionally, a glazing process is performed in which amorphous glass is baked on the substrate surface to a thickness of several tens of μm. (For example, see Patent Document 2, Patent Document 3, and Patent Document 4.)

  However, the glaze process described in these patent documents is performed in order to accurately form a fine wiring pattern in the manufacture of a substrate for a thermal head of a facsimile or a printer head. It is not something to do. In these techniques, the purpose of forming the glass layer on the substrate surface is not to improve heat dissipation but to improve the formation accuracy of the fine wiring pattern. The surface roughness is in line with its purpose, and a sufficient effect cannot be obtained in terms of heat dissipation.

Japanese Unexamined Patent Publication No. 2007-129191 Japanese Unexamined Patent Publication No. 3-146457 Japanese Unexamined Patent Publication No. 3-290382 Japanese Unexamined Patent Publication No. 1-290280

  The present invention has been made in order to solve the above-described problem, and the reflectance of the substrate body is improved without providing a reflective film, and the heat dissipation from the mounted light emitting element to the substrate is achieved. It is an object of the present invention to provide an improved light emitting element mounting substrate and a light emitting device having high light emission luminance with excellent light extraction efficiency using such a light emitting element mounting substrate.

  The light emitting element mounting substrate of the present invention is made of an inorganic insulating material and has a mounting surface including a mounting portion on which the light emitting element is mounted, and the mounting surface of the substrate main body covers at least the mounting portion. An overcoat layer made of a material mainly composed of glass, and the overcoat layer has a thickness of 3 to 20 times the surface roughness Ra of the mounting surface of the substrate body, The overcoat layer has a surface roughness Ra of 0.15 μm or less.

  In the light emitting element mounting substrate of the present invention, it is preferable that the substrate body is made of a sintered body of a glass ceramic composition containing glass powder and ceramic powder. The ceramic powder preferably includes an alumina powder and a ceramic powder having a higher refractive index than alumina. The ceramic powder is preferably at least one selected from the group consisting of titania powder, zirconia powder, stabilized zirconia powder, zinc oxide powder, barium titanate powder, and lead titanate powder.

In the light emitting element mounting substrate of the present invention, it is preferable that the glass-based material constituting the overcoat layer has a softening point of 850 ° C. or lower. By setting the softening point to 850 ° C. or lower, firing at 860 ° C. or higher and 880 ° C. or lower can be performed. Therefore, when the substrate body is obtained by firing, an overcoat layer can be formed by simultaneous firing. Furthermore, the glass constituting the overcoat layer preferably contains at least SiO ₂ and B ₂ O ₃ and at least one selected from Na ₂ O and K ₂ O. Then, the glass is represented by mol% based on oxides, the _{SiO 2 62~84%, B 2 O} 3 10 to 25%, the _{Al 2 O 3 0~5%, 0~10} % of MgO, The total content of at least one selected from Na ₂ O and K ₂ O is 1 to 5%, the total content of SiO ₂ and Al ₂ O ₃ is 62 to 84%, and selected from CaO, SrO, and BaO. A borosilicate glass powder having a total content of 5% or less is preferred when it contains at least one kind.
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.

  Furthermore, the present invention provides a light emitting device comprising the light emitting element mounting substrate of the present invention and a light emitting element mounted on the mounting portion of the light emitting element mounting substrate.

  In the light emitting element mounting substrate of the present invention, at least the mounting portion of the mounting surface of the substrate body made of an inorganic insulating material is made of a material mainly made of glass and has a thickness 3 to 20 times the surface roughness Ra of the mounting surface. An overcoat layer having a thickness is formed, and the surface roughness Ra of the overcoat layer is 0.15 μm or less and is configured to be extremely smooth, so that the contact area between the overcoat layer and the light emitting element is increased, The thickness of the die bond material having low thermal conductivity interposed between these layers can be reduced. Therefore, the thermal resistance from the light emitting element to the substrate can be reduced, and a light emitting element mounting substrate with improved heat dissipation can be provided. Further, by using this light emitting element mounting substrate, a light emitting device having excellent light extraction efficiency and high light emission luminance can be provided.

It is the top view which looked at one Embodiment of the light emitting element mounting substrate of this invention from the mounting surface (upper surface) side. It is the top view which looked at one Embodiment of the light emitting element mounting substrate of this invention from the non-mounting surface (lower surface) side. It is sectional drawing which cut | disconnected the light emitting element mounting substrate shown in FIG. 1 by the X-X 'line | wire. It is the top view which looked at the green sheet for upper layers used for manufacture of the light emitting element mounting substrate of this invention from the upper surface side. It is the top view which looked at the green sheet for inner layers used for manufacture of the light emitting element mounting substrate of this invention from the upper surface side. It is the top view which looked at the green sheet for lower layers used for manufacture of the light emitting element mounting substrate of this invention from the upper surface side. It is the top view which looked at one Embodiment of the light-emitting device of this invention from the upper surface side. It is sectional drawing which cut | disconnected the light-emitting device shown in FIG. 7 by the Y-Y 'line | wire.

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

  The light emitting element mounting substrate of the present invention is made of an inorganic insulating material, and has a substrate body having a mounting surface as a mounting portion on which the light emitting element is partially mounted, and at least the mounting portion is mounted on the mounting surface of the substrate body. An overcoat layer made of a glass-based material (hereinafter sometimes referred to as a glass material) formed so as to cover is provided. The overcoat layer has a thickness 3 to 20 times the surface roughness Ra of the mounting surface of the substrate body. Further, the surface roughness Ra of the overcoat layer is 0.15 μm or less. Here, the surface roughness Ra is represented by 3 “Definition and display of defined arithmetic average roughness” of JIS: B0601 (1994). Surfcom 1400D (model name, manufactured by Tokyo Seimitsu Co., Ltd.) Is a value measured by

  In the light emitting element mounting substrate of the present invention, an overcoat layer made of a glass material having a thickness of 3 to 20 times the surface roughness Ra of the mounting surface is formed on at least the mounting portion of the mounting surface of the substrate body. Since the surface of the formed overcoat layer is extremely smooth with a surface roughness Ra of 0.15 μm or less, when mounting and mounting a light emitting device such as an LED device on this overcoat layer, the overcoat layer The contact area between the layer and the light-emitting element is increased, and the thickness of the silicone die bond material for joining the light-emitting element interposed between these layers can be greatly reduced as compared with the case where no overcoat layer is provided. . Since the glass material constituting the overcoat layer has a thermal conductivity 10 times higher than that of the silicone die bond material, the formation of the overcoat layer has little influence on reducing heat dissipation. Thus, a light-emitting element mounting substrate with low heat resistance and high heat dissipation is obtained. Further, by using this light emitting element mounting substrate, a light emitting device having excellent light extraction efficiency and high emission luminance can be obtained.

  When the thickness of the overcoat layer is less than 3 times the surface roughness Ra of the mounting surface of the substrate body, it is difficult to sufficiently obtain the effect of reducing the unevenness of the substrate body surface by forming the overcoat layer, It is difficult to make the surface roughness Ra of the overcoat layer 0.15 μm or less. When the surface roughness Ra of the overcoat layer exceeds 0.15 μm, not only the contact area between the overcoat layer and the light emitting element is reduced, but also it is difficult to reduce the thickness of the silicone die bond material. Therefore, the effect of improving heat dissipation cannot be obtained sufficiently. Further, when the thickness of the overcoat layer exceeds 20 times the surface roughness Ra of the substrate body, the thickness of the glass layer (overcoat layer) inserted between the light emitting element to be mounted and the substrate body. As a result, the heat dissipation from the light emitting element to the substrate body may be hindered.

  Hereinafter, an embodiment of a light emitting element mounting substrate of the present invention will be described with reference to the drawings. Although this embodiment shows an example of a light emitting element mounting substrate that is applied to mount eight 2-wire type light emitting elements in electrical parallel connection, the present invention is not limited to this. .

  FIG. 1 is a plan view of an embodiment of a light-emitting element mounting substrate according to the present invention viewed from the upper surface (mounting surface) side, and FIG. 2 is a plan view viewed from the lower surface (non-mounting surface) side. FIG. 3 is a cross-sectional view of the light emitting element mounting substrate of FIG. 1 cut along line X-X ′.

  The light-emitting element mounting substrate 1 has a substrate body 2 that has a square planar shape and a substantially flat plate shape. In addition, in this specification, substantially flat form means flat form on a visual level. Hereinafter, “substantially” indicates a visual level. The substrate body 2 is made of an inorganic insulating material, and a frame 3 is formed on the upper surface (mounting surface). The frame 3 forms a cavity having a circular planar shape, and the bottom surface of the cavity is a mounting surface on which the light emitting element is mounted. A circular area surrounded by the frame 3 that is a mounting surface of the light emitting element is referred to as an entire mounting area 21.

  Examples of the inorganic insulating material constituting the substrate body 2 include an aluminum oxide sintered body (alumina ceramic), an aluminum nitride sintered body, a mullite sintered body, and a glass ceramic composition containing glass powder and ceramic powder. A ligation (LTCC) etc. are mentioned. In the present invention, LTCC is preferable from the viewpoints of high reflectivity, ease of production, easy processability, economy, and the like.

  In the present embodiment, the shape of the substrate body 2 is a square shape and a substantially flat plate shape in order to mount eight 2-wire type light emitting elements in electrical parallel connection. However, the shape, thickness, size and the like of the substrate body 2 are not particularly limited and can be changed according to the design of the light emitting device, such as the number of light emitting elements to be mounted and the arrangement method. Moreover, the raw material composition of the sintered body (LTCC) of the glass ceramic composition constituting the substrate body 2, the sintering conditions, and the like will be described in the method for manufacturing a light emitting element mounting substrate described later. The substrate body 2 preferably has a bending strength of, for example, 250 MPa or more from the viewpoint of suppressing damage or the like when the light emitting element is mounted or after use.

  A wiring conductor layer 4 electrically connected to the light emitting element is provided in the entire mounting area 21 of the substrate body 2. The wiring conductor layer 4 is disposed at one anode side or cathode side electrode (that is, the first electrode) 41 disposed in the center of the entire mounting area 21 and at the periphery of the entire mounting area 21. And a plurality of electrodes (that is, second electrodes) 42 on the opposite side of the first electrode. As the second electrode 42, the same number of eight electrodes as the light emitting elements to be mounted are arranged on the circumference surrounding the first electrode 41 at substantially equal intervals. Note that a region excluding the formation portion of the wiring conductor layer 4 (that is, the first electrode 41 and the second electrode 42) from the entire mounting region 21 of the substrate body 2 is a region where the light emitting element can be mounted. Become.

  In the present embodiment, the number of the second electrodes 42 in the wiring conductor layer 4 disposed in the entire mounting region 21 is eight, which is the same as the number of the light emitting elements to be mounted. The wiring conductor layer 4 can be formed as necessary if there are a limited number of electrodes and other necessary electrodes. That is, the planar shape and arrangement position of the first electrode 41 constituting the wiring conductor layer 4 and the planar shape and number of the second electrodes 42 are not limited to those illustrated. In addition, the constituent material of the wiring conductor layer 4 is not particularly limited as long as it is the same as the wiring conductor layer used for a normal light emitting element mounting substrate. Specifically, it will be described in the manufacturing method described later. The thickness of the wiring conductor layer 4 is preferably 5 to 15 μm.

  An overcoat layer 5 made of a glass material is formed in the mountable region of the substrate body 2. The overcoat layer 5 is provided so as to cover at least the mounting portion of the light emitting element. However, considering the ease of layer formation and the rise of the end portion of the overcoat layer 5 adversely affecting the flatness of the surface, Preferably, the conductive layer 4 is formed so as to cover almost the entire mountable region at a slight distance from the end of the conductive layer 4. In addition, the mounting part which is a part in which a light emitting element is actually mounted is shown with the code | symbol T in FIG. The eight mounting portions T on which the eight light emitting elements are mounted are respectively arranged at substantially equal intervals in an annular region between the first electrode 41 and the second electrode 42 group.

  The overcoat layer 5 has a thickness of 3 to 20 times the surface roughness Ra of the mountable region of the substrate body 2 that is the base to be formed. And the surface roughness Ra of the formed overcoat layer 5 is 0.15 μm or less.

The glass material constituting such an overcoat layer 5 will be described below. The glass material constituting the overcoat layer 5 contains at least SiO ₂ and B ₂ O ₃ and glass containing at least one selected from Na ₂ O and K ₂ O as a constituent component. .

  Moreover, this glass material can contain ceramic powder in the ratio of 10 mass% or less. The content of the ceramic powder is preferably 3% by mass or more. In the present invention, the overcoat layer made of a material mainly composed of glass means a glass material that may contain 10% by mass or less of ceramic powder. By containing ceramic powder, the strength of the overcoat layer 5 can be increased, and the heat dissipation of the overcoat layer 5 can be increased. Furthermore, from the viewpoint of chemical resistance such as acid resistance, the glass material preferably contains silica powder or alumina powder as ceramic powder.

Further, the ceramic powder contained in the glass material is at least one selected from silica powder, alumina powder, zirconia powder, and titania powder, and has an average particle diameter D ₅₀ (hereinafter sometimes simply referred to as D ₅₀ ). By using fine particles having a thickness of 2.5 μm or less, more preferably 0.5 μm or less, the printability can be improved and the end of the overcoat layer 5 can be flattened to suppress waviness on the surface of the layer. Note that D ₅₀ is a value obtained by a particle size measuring apparatus using a laser diffraction / scattering method.

The content of the ceramic powder in the glass material can be set in a predetermined range depending on the particle size. When D ₅₀ is 1~2.5μm is the content is preferably 3 to 10 mass%. 8 mass% or less is preferable and 5 mass% or less is more preferable. When D ₅₀ is less than 1μm, the content is preferably 3 to 5 mass%.

  If the ceramic powder is contained in excess of 10% by mass, the fluidity of the glass material is deteriorated, not only the flatness of the overcoat layer 5 is deteriorated, but also the sintering is liable to occur. Moreover, when content is less than 3 mass%, it becomes difficult to acquire the improvement effect of flatness.

Next, the glass which is the main component of the glass material constituting the overcoat layer 5 will be described. This glass is expressed in mol% on the basis of oxide, SiO ₂ 62-84%, B ₂ O ₃ 10-25%, Al ₂ O ₃ 0-5%, MgO 0-10%, Na ₂ The total content of at least one selected from O and K ₂ O is 1 to 5%, the total content of SiO ₂ and Al ₂ O ₃ is 62 to 84%, and at least selected from CaO, SrO and BaO A borosilicate glass having a total content of 5% or less when it contains one kind is preferred.

  Each component of such glass will be described. Hereinafter, unless otherwise specified, the composition is simply expressed as% in terms of mol% based on the following oxide.

SiO ₂ is a glass network former, a component that increases chemical durability, particularly acid resistance, and is essential. If it is less than 62%, the acid resistance may be insufficient. If it exceeds 84%, the glass melting temperature tends to be high, or the glass transition point (Tg) tends to be too high.

B ₂ O ₃ is a glass network former and is essential. If it is less than 10%, the glass melting temperature tends to be high, and the glass may become unstable. Preferably it is 12% or more. If it exceeds 25%, not only is it difficult to obtain stable glass, but chemical durability may be reduced.

Al ₂ O ₃ is not essential, but may be contained in a range of 5% or less in order to enhance the stability or chemical durability of the glass. If it exceeds 5%, the transparency of the glass may decrease.

The total content of SiO ₂ and Al ₂ O ₃ is 62 to 84%. If it is less than 62%, chemical durability may be insufficient. If it exceeds 84%, the glass melting temperature becomes high, or Tg becomes too high.

Na ₂ O and K ₂ O are components that lower Tg, and at least one of them is essential. It can contain up to 5% in total. If it exceeds 5%, chemical durability, particularly acid resistance, may deteriorate. Moreover, there exists a possibility that the electrical insulation of a sintered compact may fall. Na ₂ O, and containing any one or more of _{K 2 O,} Na 2 O, it is preferable that the total content of _{K 2} O is not less than 1%.

  MgO is not essential, but may be contained up to 10% in order to lower Tg or stabilize the glass. Preferably it is 8% or less.

  CaO, SrO, and BaO are not essential, but may be contained up to 5% in total in order to lower the melting temperature of the glass or stabilize the glass. If it exceeds 5%, the acid resistance may decrease.

  The glass for an overcoat layer of the present invention consists essentially of the above components, but may contain other components as long as the object of the present invention is not impaired. When such components are contained, the total content of these components is preferably 10% or less. However, lead oxide is not contained.

  The overcoat layer of the present invention is preferably formed by applying and baking a composition obtained by mixing such a borosilicate glass powder composed of each component and, if necessary, the ceramic powder. For example, the mixed powder of the borosilicate glass powder having the above composition and the ceramic powder is formed into a paste, screen-printed, and fired. However, the method for forming the overcoat layer is not particularly limited as long as the method can flatly form a layer having a thickness 3 to 20 times the surface roughness Ra of the mountable region of the substrate body 2.

  The other surface of the substrate body 2 is a non-mounting surface 22 on which no light emitting element is mounted, and a pair (external electrode side and cathode side) of external electrode terminals 6 is provided on the non-mounting surface 22. These external electrode terminals 6 are electrically connected to the first electrode 41 and the second electrode 42 provided on the mounting surface of the substrate body 2 through connection vias 7 formed inside the substrate body 2 and the like. It is connected to the.

  As the shapes and constituent materials of the external electrode terminals 6 and the connection vias 7, any material can be used without particular limitation as long as it is the same as that used for the light emitting element mounting substrate. Further, regarding the arrangement of the external electrode terminals 6 and the connection vias 7, the eight light emitting elements to be mounted are electrically connected via these and the wiring conductor layer 4 (that is, the first electrode 41 and the second electrode 42). It is only necessary to be arranged so as to be connected in parallel. This will be specifically described in the section of the substrate manufacturing method described later.

  In the present embodiment, in order to reduce the thermal resistance of the substrate body 2, the thermal via 8 and the heat dissipation layer 9 are embedded in the substrate body 2. The thermal via 8 has a columnar shape smaller than the mounting portion T of the light emitting element, for example, and is preferably arranged from the non-mounting surface 22 to the heat radiation layer 9 embedded inside. With such an arrangement, the flatness of the entire mounting area 21, particularly the mounting portion T, can be improved, the thermal resistance can be reduced, and the inclination when the light emitting element is mounted can be suppressed. The shape and arrangement of the thermal via 8 and the heat dissipation layer 9 will be specifically described in the section of the substrate manufacturing method described later.

  The embodiment of the light emitting element mounting substrate 1 of the present invention has been described above by taking an example, but the light emitting element mounting 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 the manufacture of the light emitting element mounting substrate 1 of the present invention configured as described above, materials and manufacturing methods generally used for the light emitting element mounting LTCC substrate can be applied. Moreover, the light emitting device of the present invention described later can also be manufactured by a normal method using a normal member except that the light emitting element mounting substrate 1 of the present invention is used.

  In the following, the method for manufacturing the substrate shown in FIGS. 1 to 3 for mounting eight 2-wire type light emitting elements in electrical parallel connection will be described as an example. A method for manufacturing the substrate will be described.

  The light emitting element mounting substrate 1 shown in FIGS. 1 to 3 can be manufactured by a manufacturing method including the following steps (A) to (E). In the following description, members, forming material layers, and the like used in the manufacture will be described with the same reference numerals as those of the finished product. For example, the overcoat layer and the overcoat glass paste layer are denoted by a symbol of 5, and the others are the same.

(A) Green sheet manufacturing process for main body A green sheet (green sheet for main body) and a frame for forming a substrate main body of a light emitting element mounting substrate using a glass ceramic composition including glass powder and ceramic powder. A green sheet for a frame is prepared for formation. As described later, the main body green sheet includes an upper layer green sheet for forming an upper layer, an inner layer green sheet for forming an inner layer, and a lower layer green sheet for forming a lower layer.

(B) Conductive paste layer forming step By forming a conductive paste layer at a predetermined position on each main body green sheet, an unfired wiring conductor layer, an unfired external electrode terminal, an unfired connection via, an unfired thermal via, A fired heat dissipation layer or the like is formed.

(C) Overcoat glass paste layer forming step In the upper layer green sheet, an overcoat glass paste layer is formed so as to cover almost the entire mountable region.

(D) Lamination process A plurality of unfired main body members (hereinafter referred to as green sheets with a conductive paste layer) obtained by forming a conductive paste layer (in addition, an overcoat glass paste layer in the upper green sheet) on the green sheet for the main body. , And a green sheet with an overcoat glass paste layer) and the like are overlapped and integrated by thermocompression bonding to obtain a green substrate.

(E) Firing step The unfired substrate is fired at 800 to 930 ° C.

  Hereinafter, each step will be further described.

(A) Green sheet production process for main body A green sheet for main body is prepared by adding a binder, and if necessary, a plasticizer, a dispersant, a solvent, etc. to a glass ceramic composition containing glass powder and ceramic powder. Then, it can be produced by forming it into a sheet by the doctor blade method and drying it. Moreover, the green sheet for a frame is obtained by processing the green sheet thus produced into a predetermined shape.

  The glass powder for main body for producing the green sheet for main body preferably has a glass transition point (Tg) of 550 ° C. or higher and 700 ° C. or lower. When Tg 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.

  Moreover, it is preferable that this glass powder precipitates a crystal | crystallization when it baked at 800 degreeC or more and 930 degrees C or less. In the case where crystals do not precipitate, there is a possibility that sufficient mechanical strength cannot be obtained. Furthermore, the thing whose crystallization peak temperature (Tc) measured by DTA (differential thermal analysis) is 880 degrees C or less is preferable. When Tc exceeds 880 ° C., the dimensional accuracy may be reduced.

As such glass powder for main body, it is 57 to 65% of SiO ₂ , 13 to 18% of B ₂ O ₃ , 9 to 23% of CaO, and Al ₂ O ₃ in terms of mol% based on the following oxides. 3-8%, those containing from 0.5 to 6% of at least one of them in total selected from _{K 2} O and Na ₂ O are preferred. By using the glass having such a composition, it becomes easy to improve the surface flatness of the substrate body 2.

Here, SiO ₂ serves as 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 Tg 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 temperature or Tg may be too 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 Tg may be excessively high. 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 Tg. 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 Tg. When the total content of K ₂ O and Na ₂ O is less than 0.5%, the glass melting temperature and Tg 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 glass powder for main bodies is not necessarily limited to what consists only of the said component, Other components can be contained in the range with which various characteristics, such as Tg, are satisfy | filled. When other components are contained, the total content is preferably 10% or less.

  The glass powder for main body is obtained by producing glass having the above composition by a melting method and pulverizing it by a dry pulverization method or a wet pulverization method. In the case of the wet pulverization method, it is preferable to use water or ethyl alcohol as a solvent. Examples of the pulverizer include a roll mill, a ball mill, and a jet mill.

The 50% particle size (D ₅₀ ) of the glass powder for main body is preferably 0.5 μm or more and 2 μm or less. If D ₅₀ of the glass powder is less than 0.5 [mu] m, it glass powder is likely to agglomerate, handle not only difficult, uniform dispersion becomes difficult. On the other hand, if the D ₅₀ of the glass powder exceeds 2μm, there is a possibility that increase and insufficient sintering of the glass softening temperature is generated. The particle diameter may be adjusted by classification as necessary after pulverization, for example.

  As the ceramic powder, those conventionally used for the production of LTCC substrates can be used. For example, alumina powder, zirconia powder, or a mixture of alumina powder and zirconia powder can be suitably used. In particular, it is preferable to use a ceramic powder (hereinafter referred to as a high refractive index ceramic powder) having a higher refractive index than alumina together with the alumina powder.

The high refractive index ceramic powder is a component for improving the reflectivity of the base body obtained by sintering by the firing process described below. For example, titania powder, zirconia powder, stabilized zirconia powder, zinc oxide powder, titanium Examples thereof include barium acid powder and lead titanate powder. For example, the refractive index of alumina is about 1.8, while 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. ing. D ₅₀ of these ceramic powders is preferably 0.5 μm or more and 4 μm or less.

  By mixing and mixing such glass powder and ceramic powder such that the glass powder is 30% by mass to 50% by mass and the ceramic powder is 50% by mass to 70% by mass, the glass ceramic composition is mixed. A thing is obtained. Moreover, a desired slurry can be 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, acrylic resin and the like can be suitably used. As the plasticizer, for example, dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate and the like can be used. As the solvent, organic solvents such as toluene, xylene, 2-propanol and 2-butanol can be suitably used.

  The slurry thus obtained is formed into a sheet by a doctor blade method or the like and dried to produce three green sheets for the main body (upper layer green sheet, lower layer green sheet and inner layer green sheet). . In addition, a green sheet for a frame is manufactured by processing the green sheet manufactured in the same manner into a predetermined shape.

(B) Conductive paste layer forming step A conductive paste layer for forming a wiring conductive layer, external electrode terminals, connection vias, thermal vias, heat dissipation layers, etc. on the surface and inside of the green sheet for main body produced in the above step. Form. That is, as shown in FIG. 4, a circular first electrode conductor paste layer 41 is formed in the center of the entire mounting area 21 corresponding to the element mounting surface in the upper layer green sheet 23.

  In addition, a ring-shaped connecting conductor paste layer 43 is formed so as to surround the first electrode conductor paste layer 41, and the eight second electrode conductor paste layers 42 are connected to the connecting conductor paste layer 43. It is formed at substantially equal intervals so as to extend inward from the inside. Further, the connection via conductor paste layer 7 is formed through the upper layer green sheet 23 at a predetermined position of the central portion of the first electrode conductor paste layer 41 and the connecting conductor paste layer 43.

  Further, as shown in FIG. 5, in the inner layer green sheet 24, a heat dissipating layer conductor paste layer 9 is formed on the upper surface thereof, and a plurality of connection via conductor paste layers 7 are formed so as to penetrate the green sheet. A plurality of conductor paste layers 8 for thermal vias are formed.

  Further, as shown in FIG. 6, a plurality of connection via conductor paste layers 7 and a plurality of thermal via conductor paste layers 8 are formed so as to penetrate the lower layer green sheet 25, and A conductor paste layer 6 for external electrode terminals is formed on the lower surface. Each green sheet has a large number of regions corresponding to a large number of light emitting devices, and these are divided after the final firing step. In FIGS. 4 to 6, each green sheet corresponds to a single light emitting device. An area for forming one light emitting element mounting substrate is shown.

  First and second electrode conductor paste layers 41 and 42, a connecting conductor paste layer 43, a connection via conductor paste layer 7, a heat dissipation layer conductor paste layer 9, a thermal via conductor paste layer 8, and an external electrode terminal Examples of the method for forming the conductive paste layer 6 include a method of applying and filling the conductive paste by screen printing. The thickness of these formed conductive paste layers is such that the first and second electrodes, connection wirings, connection vias, heat dissipation layers, thermal vias, and external electrode terminals finally obtained have a predetermined thickness. It is adjusted to become.

  As the conductive paste, for example, a paste obtained by adding a vehicle such as ethyl cellulose to a metal powder mainly composed of copper, silver, gold or the like, and a solvent or the like as required can be used. As the metal powder, silver powder, metal powder composed of silver and platinum, or metal powder composed of silver and palladium are preferably used.

(C) Overcoat glass paste layer forming step In the upper layer green sheet, overcoat is applied by screen printing so as to cover almost the entire mountable region except for the vicinity of the wiring conductor paste layer 4 formed in the step (B). A glass paste layer 5 is formed.

The overcoat glass paste is a paste prepared by adding a vehicle such as ethyl cellulose to a composition obtained by mixing the glass powder for the overcoat layer and the ceramic powder as necessary, and a solvent as necessary. What was made into a shape can be used. The film thickness of the overcoat glass paste layer 5 to be formed is such that the thickness of the overcoat layer 5 finally obtained is 3 to 20 times the surface roughness Ra of the mountable region of the substrate body 2. In addition, the surface roughness Ra of the overcoat layer 5 is adjusted to be 0.15 μm or less. The surface roughness Ra of the overcoat layer 5 can be adjusted not only by the thickness of the overcoat layer 5, but also by the particle size and composition of the glass powder for the overcoat layer, the paste kneading method and the kneading time. . That is, as the glass powder for the overcoat layer, a glass powder having a composition and particle size excellent in fluidity that sufficiently melts during firing is used, and the composition of the mixture with the ceramic powder is excellent in fluidity during firing. By optimizing the kneading method and time, the surface roughness Ra of the overcoat layer 5 can be reduced.
For example, when the surface roughness Ra of the mountable region of the substrate body 2 is 0.30 to 0.35 μm, the thickness of the overcoat layer 5 after firing is set to 0.9 to 7.0 μm.

(D) Lamination process Green sheet with conductor paste layer (unfired main body member) obtained in step (B) and green sheet with overcoat glass paste layer obtained in step (C) in a predetermined order The green sheet for frame is further stacked on the upper layer green sheet 23, and then integrated by thermocompression bonding. Thus, an unfired substrate is obtained.

(E) Firing process About the unbaked board | substrate obtained at the said process, after degreasing | defatting a binder etc. as needed, the baking for sintering a glass ceramic composition etc. is performed and it is set as the light emitting element mounting substrate 1. FIG.

  The degreasing described above is performed, for example, under the condition of holding at a temperature of 500 ° C. to 600 ° C. for 1 hour to 10 hours. 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. On the other hand, 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, and if it exceeds this, productivity and the like may be lowered.

  In addition, in the firing, the time can be appropriately adjusted in a temperature range of 800 ° C. to 930 ° C. in consideration of obtaining a dense structure of the base body 2 and productivity. 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 a temperature of 860 ° C. or more and 880 ° C. or less is particularly preferable. If the firing temperature is less than 800 ° C., the base body 2 may not be obtained as a dense structure. On the other hand, if the firing temperature exceeds 930 ° C., the productivity may be lowered due to deformation of the base body 2. Further, when a metal paste containing a metal powder containing silver as a main component is used as the conductor paste, if the firing temperature exceeds 880 ° C., there is a risk that the predetermined shape cannot be maintained due to excessive softening. .

  Thus, the light-emitting element mounting substrate 1 is obtained. After firing, the surface of the wiring conductor layer 4 (first and second electrodes 41, 42) exposed on the mounting surface is coated as necessary. It is also possible to dispose a conductive protective film used for protecting the conductor in the light emitting element mounting substrate 1 such as Ni / gold plating two-layer plating.

  The method for manufacturing the light-emitting element mounting substrate 1 has been described above, but the frame green sheet does not have to be a single green sheet, and may be a laminate of a plurality of green sheets. Further, the number of main body green sheets excluding the frame green sheet is not necessarily three, and may be two or four or more. Further, the order of forming each part can be appropriately changed as long as the light emitting element mounting substrate 1 can be manufactured.

  Next, a preferred embodiment of a light emitting device having the light emitting device mounting substrate 1 of the present invention will be described with reference to the drawings. However, the light emitting device of the present invention is not limited to this. 7 is a plan view of an embodiment of the light emitting device of the present invention as viewed from the upper surface side, and FIG. 8 is a cross-sectional view of the light emitting device of FIG. 7 cut along line Y-Y ′. FIG. 7 shows a state where the resin sealing layer is removed.

  The light-emitting device 10 of the present invention is mounted on the above-described light-emitting element mounting substrate 1 of the present invention and the mounting portion of the light-emitting element mounting substrate 1, and a pair of electrodes each have a predetermined wiring conductor layer 4 (first 8 light-emitting elements (for example, LED elements) 11 of a two-wire type, which are wire-bonded to one electrode 41 and second electrode 42) and connected in parallel.

  In the light emitting device 10 of the present invention, all the eight light emitting elements 11 are rectangular parallelepiped light emitting elements whose bottom surfaces are squares of the same size, and are arranged on the eight mounting portions T of the light emitting element mounting substrate 1, respectively. Then, it is fixed to the mounting portion using a silicone die bond material (not shown) that is an adhesive.

  One of the electrodes (not shown) of each light emitting element 11 is connected to the second electrode 42 located at the center of the entire mounting region 21 of the light emitting element mounting substrate 1 by the bonding wire 12, and the other Are connected by the bonding wire 12 to the closest electrode in the group of eight second electrodes 42. The 16 bonding wires 12 connecting the 8 to 16 electrodes of the 8 light emitting elements 11 are arranged so as not to cross each other. Further, a sealing layer 13 made of mold resin is provided so as to cover these light emitting elements 11 and bonding wires 12.

  The arrangement of the light emitting element 11 in the light emitting device 10 of the present invention is such that at least the electrode of the light emitting element 11 and the wiring conductor layer 4 (first electrode 41 and second electrode 42) of the light emitting element mounting substrate 1 are connected. As long as the bonding wires 12 do not cross each other, the arrangement is not limited to the arrangement shown in FIG.

  According to the light emitting device 10 of the present invention, the overcoat layer 5 having a thickness 3 to 20 times the surface roughness Ra of the mounting surface is formed on the mounting surface of the substrate body 2. Since the light emitting element mounting substrate 1 having a thickness Ra of 0.15 μm or less is used, the heat dissipation from the light emitting element 11 to the substrate body 2 is excellent, and the light extraction efficiency is excellent. Luminous light emission is possible. Such a light emitting device 10 can be suitably used, for example, as a backlight for a mobile phone, a large-sized liquid crystal display, etc., illumination for automobiles or decoration, and other light sources.

  Next, specific examples of the present invention will be described. The present invention is not limited to these examples.

Examples 1 to 3, Comparative Examples 1 and 2
The light emitting element mounting substrate as shown in FIGS. 1 to 6 and the light emitting device shown in FIGS. 7 and 8 were manufactured by the following method.

First, main body green sheets (upper layer green sheet, lower layer green sheet, and inner layer green sheet) for manufacturing the substrate body 2 of the light emitting element mounting substrate 1 were manufactured. In the production of the green sheet for the main body, in terms of mol% based on oxide, SiO ₂ is 60.4%, B ₂ O ₃ is 15.6%, Al ₂ O ₃ is 6%, CaO is 15%, K _The raw materials were blended and mixed so that ₂ O was 1% and Na ₂ O was 2%. The 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. did. This glass was pulverized with an alumina ball mill for 40 hours to produce a glass powder for a main body. In addition, ethyl alcohol was used as a solvent for pulverization.

  Next, 38% by mass of this glass powder, 38% by mass of alumina filler (manufactured by Showa Denko KK, trade name: AL-45H), zirconia filler (manufactured by Daiichi Rare Element Chemical Industries, trade name: HSY-3F-J) ) Was mixed so as to be 24% by mass, and mixed to produce a glass ceramic composition for a substrate body. 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. .

  This slurry was applied onto a PET film by a doctor blade method, and the dried green sheet was laminated so that the thickness after firing was 0.5 mm to produce a green sheet for a main body. Further, a green sheet for a frame was manufactured by processing a green sheet manufactured in the same manner as the green sheet for a main body into a predetermined shape.

  On the other hand, conductive metal 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, and the solvent is set so that the solid content is 85 mass%. After being dispersed in α-terpineol, the mixture was kneaded in a porcelain mortar for 1 hour, and further dispersed three times with a three roll to produce a metal paste (conductor paste).

  On the upper surface of one of the green sheets for the main body (upper green sheet 23), the conductor paste is screen-printed with the pattern shown in FIG. 4 so that the first electrode, the second electrode, and the connection are used. And forming a through hole having a diameter of 0.15 mm using a hole puncher in a portion corresponding to the connection via, and filling the conductor paste by a screen printing method, A connection via conductor paste layer 7 was formed.

  In addition, the conductor paste layer 9 for the heat radiation layer is formed on the upper surface of the green sheet 24 for the inner layer by screen printing with the pattern shown in FIG. 5, and the portions corresponding to the thermal vias and connection vias are perforated. Through holes having a diameter of 0.2 mm and a diameter of 0.15 mm were formed using a machine, and a conductor paste was filled by a screen printing method to form a thermal via conductor paste layer 8 and a connection via conductor paste layer 7.

  Furthermore, the conductor paste layer 6 for external electrode terminals is formed on the lower surface of the lower layer green sheet 25 by screen printing in the pattern shown in FIG. 6, and holes are formed in portions corresponding to the thermal vias and connection vias. Through holes having a diameter of 0.2 mm and a diameter of 0.15 mm were respectively formed using an emptying machine, and a conductive paste was filled by screen printing to form a thermal via conductor paste layer 8 and a connection via conductor paste layer 7. .

  Next, in Examples 1 to 3 and Comparative Example 2, the overcoat glass paste was screen-printed with the pattern shown in FIG. 4 on the mounting surface of the upper layer green sheet 23 on which the conductor paste layer was formed. A paste layer 5 was formed. In Comparative Example 1, such overcoat glass paste layer 5 was not formed. The thickness of the overcoat glass paste layer 5 in Examples 1 to 3 is such that the thickness of the overcoat layer after firing is in the range of 3 to 20 times the surface roughness Ra of the mountable region of the substrate body 2. The thickness was adjusted to be as shown in Table 1. Moreover, the thickness of the overcoat glass paste layer 5 in Comparative Example 2 is such that the thickness of the overcoat layer after baking exceeds 20 times the surface roughness Ra of the mountable region of the substrate body 2. It was adjusted. The surface roughness Ra of the mountable area of the substrate body 2 corresponds to the surface roughness Ra of the mounting surface of the light emitting element mounting substrate 1 obtained in Comparative Example 1, and the value is 0.31 μm as will be described later. Met.

The overcoat glass paste was prepared as shown below. First, raw materials are blended and mixed so that SiO ₂ is 81.6%, B ₂ O ₃ is 16.6%, and K ₂ O is 1.8% in terms of mol% based on oxide. The 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 with an alumina ball mill for 8 to 60 hours to produce an overcoat glass powder. In addition, ethyl alcohol was used as a solvent for pulverization.

  Subsequently, this glass powder was blended and mixed so that 95% by mass and silica fine powder (manufactured by Nippon Aerosil Co., Ltd., trade name: AEROSIL 380, average particle size 7 nm) were 5% by mass. Subsequently, it mix | blended so that the obtained mixture might be 60 mass% and a resin component (what contains ethyl cellulose and alpha terpineol in the ratio of 85:15 by mass ratio) may be 40 mass%. Then, an overcoat glass paste was prepared by kneading in a zirconia mortar for 3 hours and further dispersing three times with an alumina three-roll.

  Next, the green sheet for the upper layer with the overcoat glass paste layer thus prepared, the green sheet for the inner layer with the conductive paste layer, and the green sheet for the lower layer (unfired main body member) are superposed in a predetermined order, and the upper layer The green sheet for the frame body was overlaid on the green sheet for use, and then integrated by thermocompression bonding. Thus, an unfired substrate was obtained.

  The obtained non-fired substrate was degreased by holding at 550 ° C. for 5 hours, and further fired by holding at 870 ° C. for 30 minutes to produce a light-emitting element mounting substrate 1. In the obtained light emitting element mounting substrate 1, the thickness of the overcoat layer 5 after firing was measured by cross-sectional observation. For cross-sectional observation, the cross-section including the overcoat layer 5 was mirror-polished and measured with an electron microscope (Hitachi High-Technologies S3000) at a magnification of 1500 times. In Examples 1 to 3 and Comparative Example 2, the surface roughness Ra of the overcoat layer 5 was measured with Surfcom 1400D (manufactured by Tokyo Seimitsu Co., Ltd.). The measurement results are shown in Table 1. In Comparative Example 1 in which the overcoat layer 5 was not provided, the surface roughness Ra of the mounting surface of the substrate body 2 was measured in the same manner. The measurement results are shown in the column of the surface roughness Ra of the overcoat layer 5 and the like.

  Next, eight 2-wire type LED elements of the same shape and size were arranged and mounted on the eight mounting portions T of the light-emitting element mounting substrate 1 produced as described above. Specifically, the LED elements (product name: ES-CEBLV24, manufactured by Epistar Co., Ltd.) are fixed to the eight mounting portions 5 with a die bond material (product name: KER-3000-M2 manufactured by Shin-Etsu Chemical Co., Ltd.), A pair of electrodes included in each LED element was electrically connected to the first electrode 41 and the second electrode 42 by the bonding wire 12, respectively. In this way, eight LED elements were electrically connected in parallel. Furthermore, the sealing layer 13 was formed using the sealing agent (The Shin-Etsu Chemical Co., Ltd. make, brand name: SCR-1016A).

  About the light-emitting device 10 obtained in this way, the thermal resistance was measured with the following method. That is, the thermal resistance of the light-emitting element mounting substrate 1 in the light-emitting devices 10 obtained in Examples 1 to 3 and Comparative Examples 1 and 2 was measured using a thermal resistance measuring instrument (trade name: TH-2167, manufactured by Gwangon Electric Co., Ltd.). ). The applied current was set to 960 mA, current was applied until the voltage drop was saturated, the saturation temperature was calculated from the dropped voltage and the temperature coefficient derived from the temperature-voltage drop characteristics of the light emitting element, and the thermal resistance was obtained.

  Table 1 shows the measurement results of thermal resistance. The thermal resistance is shown as a relative value when the thermal resistance in the light emitting device 10 of Comparative Example 1 in which the overcoat layer 5 is not formed on the mounting surface of the substrate body is 100. It means that heat dissipation is so favorable that a numerical value is small.

  From Table 1, the overcoat layer 5 has a thickness of 3 to 20 times the surface roughness Ra of the mounting surface of the substrate body 2 (corresponding to the surface roughness Ra in Comparative Example 1) of 0.31 μm, and In the light emitting devices 10 of Examples 1 to 3 in which the surface roughness Ra of the overcoat layer 5 itself is 0.15 μm or less, the thermal resistance is higher than that of the light emitting device 10 of Comparative Example 1 that does not have the overcoat layer 5. Is significantly reduced, and it can be seen that the heat dissipation is high.

  In the light emitting device 10 of Comparative Example 2 in which the thickness of the overcoat layer 5 exceeds 20 times the surface roughness Ra of the mounting surface of the substrate body 2, the surface roughness Ra of the overcoat layer 5 is extremely small. Although the smoothness and flatness of the surface of the layer 5 is good, a thick overcoat layer made of a glass material becomes an obstacle to heat conduction, so that the thermal resistance is high.

According to the present invention, the light-emitting element mounting substrate has high reflectivity and excellent heat dissipation. Therefore, when this substrate is used as a light-emitting device, the light extraction efficiency is good and the brightness is high. Can be obtained. And the light-emitting device of this invention using such a light emitting element mounting substrate can be used conveniently as backlights, such as a mobile telephone and a large sized liquid crystal display, the illumination for motor vehicles or decoration, and another light source, for example.
The entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2010-209663 filed on September 17, 2010 are incorporated herein by reference. .

DESCRIPTION OF SYMBOLS 1 ... Light emitting element mounting substrate, 2 ... Substrate body, 3 ... Frame, 4 ... Wiring conductor layer (wiring conductor paste layer), 5 ... Overcoat layer (overcoat glass paste layer), 6 ... External electrode terminal (external) Conductor paste layer for electrode terminals), 7 ... Connection via (conductor paste layer for connection via), 8 ... thermal via (conductor paste layer for thermal via), 9 ... heat dissipation layer (conductor paste layer for heat dissipation layer), 10 ... light emission Device: 11 ... Light emitting element, 12 ... Bonding wire, 13 ... Sealing layer, 21 ... Whole mounting area, 41 ... First electrode (first electrode conductor paste layer), 42 ... Second electrode (second electrode) Electrode conductor paste layer), 43... Connecting conductor layer (connecting conductor electrode conductor paste layer).

Claims (8)

A substrate body made of an inorganic insulating material and having a mounting surface including a mounting portion on which a light emitting element is mounted;
An overcoat layer made of a material mainly composed of glass, formed to cover at least the mounting portion on the mounting surface of the substrate body;
The overcoat layer has a thickness of 3 to 20 times the surface roughness Ra of the mounting surface of the substrate body, and the surface roughness Ra of the overcoat layer is 0.15 μm or less. A light-emitting element mounting substrate.   The light emitting element mounting substrate according to claim 1, wherein the substrate body is made of a sintered body of a glass ceramic composition containing glass powder and ceramic powder.   The light emitting element mounting substrate according to claim 2, wherein the ceramic powder includes an alumina powder and a ceramic powder having a higher refractive index than alumina.   4. The light emitting device according to claim 2, wherein the ceramic powder is at least one selected from the group consisting of titania powder, zirconia powder, stabilized zirconia powder, zinc oxide powder, barium titanate powder, and lead titanate powder. Device mounting board.   5. The light-emitting element mounting substrate according to claim 1, wherein the glass-based material constituting the overcoat layer has a softening point of 850 ° C. or lower. Glass, at least, contain SiO ₂ and _B 2 _{O 3,} and any one of claims 1 to 5, containing at least one selected from Na ₂ O and _{K 2} O constituting the overcoat layer A substrate for mounting a light-emitting element according to 1. The glass is expressed in terms of mol% based on oxide, and SiO ₂ is 62 to 84%, B ₂ O ₃ is 10 to 25%, Al ₂ O ₃ is 0 to 5%, MgO is 0 to 10%, Na _2. The total content of at least one selected from O and K ₂ O is 1 to 5%, the total content of SiO ₂ and Al ₂ O ₃ is 62 to 84%, and at least selected from CaO, SrO and BaO The board | substrate for light emitting element mounting of Claim 6 which is the borosilicate glass whose sum total is 5% or less when it contains 1 type. A light emitting element mounting substrate according to any one of claims 1 to 7,
A light emitting device comprising: a light emitting element mounted on the mounting portion of the light emitting element mounting substrate.

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