JP2012033781A - Substrate for mounting light emitting element, and light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for mounting a light emitting element which is an LTCC substrate for mounting a plurality of two wire type light emitting elements so as to electrically connect them in parallel, and a light emitting device using the substrate and having excellent light extraction efficiency and high emission luminance.SOLUTION: The substrate for mounting the light emitting elements has a substrate body made from a sintered body of a glass ceramic composition and having a mounting surface including a mounting part of the light emitting elements, and a wiring conductor layer provided so as to be connected by wire bonding to a pair of electrodes which each of the light emitting elements has on the mounting surface of the substrate body, where the sum of areas of the mounting parts of the plurality of light emitting elements is 10-35% of an area of a mountable region on the mounting surface, and a relative external quantum efficiency is 90 or greater. The relative external quantum efficiency is a value relative to external quantum efficiency set as 100 when a total mounting region obtained by adding a formation part of the wiring conductor layer to the mountable region is covered with a silver reflection film having reflectance of 95%.

Description

  The present invention relates to a light-emitting element mounting substrate 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 heat generated from the light emitting element is quickly dissipated as a substrate for mounting the light emitting element such as the LED element, and sufficient light emission luminance is achieved. What can be obtained is required.

  Conventionally, for example, an alumina substrate has been used as a light emitting element mounting substrate. In addition, since the alumina substrate has a low reflectance and a low thermal conductivity, the use of an aluminum nitride substrate having a higher thermal conductivity has been studied. However, since the aluminum nitride substrate has a high raw material cost and is difficult to sinter, it requires high-temperature firing, which tends to increase the process cost. Furthermore, since the aluminum nitride substrate has a small coefficient of thermal expansion, when it is mounted on a general-purpose printed circuit board, sufficient connection reliability may not be obtained due to the difference in coefficient of thermal expansion.

  In order to solve such problems, the use of a low-temperature co-fired ceramic substrate (hereinafter referred to as an LTCC substrate) as a light-emitting element mounting substrate has been studied. The LTCC substrate is composed of a sintered body of a composition of glass and ceramic powder such as alumina powder, and the refractive index difference between glass and ceramic is large, and the ratio of both interfaces facing the light incident direction is large. And since the particle size (thickness) of ceramic powder is larger than a use wavelength, since a high reflectance is obtained, the light from a light emitting element can be utilized efficiently, and the emitted-heat amount can be reduced as a result. 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.

  The LTCC substrate is one of the features that has a high reflectance as described above as a substrate for mounting a light emitting element. However, for the purpose of reflecting light emitted from the light emitting element as far forward as possible, the LTCC substrate is used. A silver reflective film is formed on the surface of the substrate. An attempt has been made to provide a protective layer (overcoat glass layer) made of glass or the like on the surface of the silver reflective film in order to prevent the reflectance from being reduced due to oxidation or sulfuration of the silver reflective film (for example, Patent Document 1, Patent). (Refer to Literature 2.)

  However, the structures described in Patent Document 1 and Patent Document 2 are not sufficient in terms of light extraction efficiency. That is, when a silver reflective film is provided on an LTCC substrate or the like, the light extraction efficiency is higher when the area of the silver reflective film is as large as possible. However, a wire bonding type light emitting element normally mounted on an LTCC substrate or the like is A wiring conductor layer is required on the mounting surface, and it is necessary 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 LTCC substrate, and most of the incident light is diffusely reflected within the substrate, making it difficult to re-radiate. There has been a problem of lowering the reflectivity.

  In particular, when a plurality of light emitting elements are mounted, they are electrically connected in parallel in order to prevent a high voltage. In such a light emitting element mounting substrate, both of the pair of electrodes are connected by wire bonding. Since each of the light emitting elements to be connected (hereinafter referred to as “2-wire type” as necessary) requires a pair of wiring conductor layers (electrodes) for wire bonding on the mounting surface, Sufficient light extraction efficiency could not be obtained. That is, the wiring conductor layer is usually gold-plated for the purpose of improving the wire bonding property and preventing corrosion. If the area of the wiring conductor layer is large, the light absorption by the gold becomes large and sufficient. The light extraction efficiency cannot be obtained. In addition, when the wiring conductor layer is provided, for example, between light emitting elements having a relatively large light emission intensity, not only is it impossible to form a silver reflective film having high reflection efficiency in this region, but also silver reflection as described above. Since light escapes from the gap between the film and the wiring conductor layer, there is a problem that sufficient light extraction efficiency cannot be obtained.

  In addition, a certain distance is also provided between the wiring conductor layer and the protective layer so that a protective layer such as an overcoat glass layer formed on the silver reflective film does not cover the wiring conductor layer (electrode). (Gap) must be provided. As a result, there is a problem that the area of the silver reflection film is further reduced, the reflectivity is lowered, or the region where the light emitting element can be mounted becomes narrow.

For example, in a light emitting element mounting substrate having an outer diameter of 5 mm × 5 mm, which is a general size, an area in which a light emitting element excluding the frame body forming portion and the wiring conductor layer forming portion from the entire mounting surface of the substrate (hereinafter referred to as an area) The area of the mountable area is about 15 mm ² , but when a two-wire type light emitting element is mounted in parallel connection, the total area of the mounting portion where the light emitting element is actually mounted is It was 10% or less of the possible area. If a large number of light emitting elements are mounted so that the total area of the mounting portion exceeds 10%, the gap between the wiring conductor layer (electrode) and the silver reflective film increases and light leakage from there increases. The light extraction efficiency was greatly reduced. Moreover, since the flat area | region at the time of forming a protective film on a silver reflection film becomes narrow, the light emitting element will be mounted also in the area | region where flatness is inadequate, and the heat dissipation fell.

JP 2009-231440 A JP 2010-34487 A

  The present invention has been made to solve the above problem, and is an LTCC substrate for mounting a plurality of two-wire type light emitting elements so as to be electrically connected in parallel. It is an object of the present invention to provide a light-emitting element mounting substrate that can improve the light extraction efficiency, and a light-emitting device that uses the same and has excellent light extraction efficiency and high emission luminance.

  The light emitting element mounting substrate of the present invention is a light emitting element mounting substrate for mounting a plurality of light emitting elements in which a pair of electrodes are both connected to the substrate by wire bonding so as to be electrically connected in parallel. A substrate body comprising a sintered body of a glass ceramic composition containing glass powder and a ceramic filler, and having a mounting surface including a mounting portion on which the light emitting element is mounted; Each of the pair of electrodes of each light emitting element has a wiring conductor layer provided so as to be connected by wire bonding, and the total area of the mounting portions of the plurality of light emitting elements is the light emitting element on the mounting surface. 10% to 35% of the area of the mountable region, and the relative external quantum efficiency is opposite to the entire mountable region obtained by adding the formation portion of the wiring conductor layer to the mountable region. The external quantum efficiency when covered at a rate of 95% of the silver reflection film with the value set to 100, characterized in that 90 or more.

  In the light emitting element mounting substrate according to the present invention, the wiring conductor layer includes a first electrode disposed in a central portion of the entire mounting area and the light emitting element disposed in a peripheral portion of the entire mounting area. The number of the second electrodes can be the same as the number of the second electrodes. The entire mounting area is substantially circular (meaning circular at the visual level; the same applies hereinafter), and the second electrode is the first electrode disposed in the center of the entire mounting area. It is preferable from the viewpoint of improving the light extraction efficiency to be arranged at substantially equal intervals (meaning equal intervals at the visual level; the same applies hereinafter) on the surrounding circumference. Furthermore, the substrate body is preferably made of a sintered body of a glass ceramic composition containing glass powder and alumina powder and ceramic powder having a higher refractive index than alumina.

  Further, the present invention provides a light emitting element mounting substrate according to the present invention and a plurality of electrodes mounted on the mounting portion of the light emitting element mounting substrate, wherein a pair of electrodes are both connected to the wiring conductor layer by wire bonding. Provided is a light-emitting device including a light-emitting element.

  According to the present invention, in the substrate for mounting a plurality of two-wire type light emitting elements so as to be electrically connected in parallel, the total area of the mounting portions of the light emitting elements is changed from the entire mounting area to the wiring conductor layer. 10 to 35% of the area of the mountable region excluding the formation portion, and the relative external quantum efficiency is 90 or more (the external quantum efficiency when the entire mounting region is covered with a silver reflection film having a reflectance of 95% is 100 Therefore, it is possible to provide a light-emitting element mounting substrate on which a large number of light-emitting elements can be mounted without causing a decrease in light extraction efficiency. 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 one Embodiment of the light-emitting device of this invention from the upper surface side. FIG. 5 is a cross-sectional view of the light emitting device shown in FIG. 4 cut along line Y-Y ′. 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.

  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 a light emitting element mounting substrate for mounting a plurality of two-wire type light emitting elements so as to be electrically connected in parallel, and includes a glass powder and a ceramic filler. A substrate body made of a sintered body of a ceramic composition and having a mounting surface to be a mounting portion on which a light emitting element is partially mounted, and a pair of electrodes of each of the light emitting elements on the mounting surface of the substrate body And a wiring conductor layer provided so as to be connected by wire bonding.

  The total area of the mounting parts on which the plurality of light emitting elements are mounted (hereinafter also referred to as the total area of the mounting parts) is a mountable area on the mounting surface (excluding the formation part of the wiring conductor layer from the entire mounting area). The area is 10 to 35% of the area, and the relative external quantum efficiency is 90 or more. It is preferable that the total area of the mounting portion is 10 to 30% of the area of the mountable region (hereinafter also referred to as a mountable region area) and the relative external quantum efficiency is 95 or more. It is more preferable that the total area of the mounting portion is 23 to 28% of the mountable area and the relative external quantum efficiency is 95 or more.

  Note that the external quantum efficiency refers to a ratio of light energy extracted to the outside among electric energy injected into the light emitting element. The relative external quantum efficiency (90 or more) in the light emitting element mounting substrate of the present invention is referred to as an external quantum efficiency (hereinafter referred to as a reference external quantum efficiency) when the entire mounting region is covered with a silver reflecting film having a reflectance of 95%. ) Is 100 and relative value. The number of light emitting elements mounted on the light emitting element mounting substrate is two or more, but it is preferable to mount 5 to 8 light emitting elements. A more preferable number of light emitting elements is eight. That is, even when the number of light emitting elements is eight and the total area of the mounting portion is increased to 35% of the mountable area, a high relative external quantum efficiency of 90 or more can be realized.

  Here, an area excluding the formation area such as the frame body from the entire mounting surface of the substrate is referred to as an entire mounting area in this specification. The mountable region indicates a region where a semiconductor element can be mounted on the mounting surface of the substrate body, and is a region obtained by removing the wiring conductor layer forming portion from the entire mounting region. That is, in this specification, a region obtained by adding the wiring conductor layer forming portion to the mountable region is the entire mounting region.

  According to the present invention, in the light-emitting element mounting substrate for mounting a plurality of 2-wire type light-emitting elements so as to be electrically connected in parallel, the total area of the light-emitting element mounting portions is the mountable area. Since it is 10 to 35% of the area and the relative external quantum efficiency is 90 or more (reference external quantum efficiency is 100), the light extraction efficiency can be improved by using this substrate. And a light emitting device with high emission luminance can be obtained. That is, even when the total area of the light emitting element mounting portion is increased to 35% of the area of the mountable area by mounting a plurality of (for example, eight) light emitting elements on the light emitting element mounting substrate. Since light extraction efficiency can be ensured, a light emitting device with high emission luminance can be provided.

  Hereinafter, an embodiment of a light emitting element mounting substrate for mounting eight light emitting elements of two wire types to be electrically connected in parallel, to which the light emitting element mounting substrate of the present invention is preferably applied, is shown in the drawings. Based on this description, 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 includes a substrate body 2 having a square shape of, for example, 5 mm × 5 mm and a substantially flat plate shape (for example, a thickness of 0.5 mm). In the present specification, “substantially flat plate” means the same as the flat plate shape at the visual level. The substrate body 2 is made of a sintered body of a glass ceramic composition containing glass powder and a ceramic filler, and has an upper surface (mounting surface) having, for example, a narrowest portion having a width of 0.3 mm and a height of 0.5 mm. A body 3 is formed. 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.

  In the present embodiment, the substrate body 2 has a square planar shape and a substantially flat plate shape in order to mount eight 2-wire type light emitting elements so as to be electrically connected in parallel. In the invention, 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. The raw material composition of the sintered body 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 includes one anode-side or cathode-side electrode (first electrode) 41 disposed in the center of the entire mounting area 21 and a first portion disposed in the periphery of the entire mounting area 21. It has a plurality of electrodes (second electrodes) 42 opposite to the one 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. As described above, the region excluding the formation portion of the wiring conductor layer 4 (the first electrode 41 and the second electrode 42) from the entire mounting region 21 of the substrate body 2 is the mounting of the light emitting element. It becomes a possible area.

  In the mountable area of the substrate body 2, eight square mounting parts 5, which are parts where eight light emitting elements are actually mounted, include the first electrode 41 and the second electrode 42 group. The light emitting elements are arranged in an annular region between them so that one side of the light emitting element is parallel to one side of the substrate body 2 and are arranged at substantially equal intervals. The total area of these eight mounting portions 5 is 10 to 35% of the mountable region area excluding the formation portion of the wiring conductor layer 4 from the entire mounting region 21, and the relative external quantum efficiency. Is a relative value of 90 or more with the reference external quantum efficiency as 100.

  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. 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.

  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 (the first electrode 41 and the second electrode 42). What is necessary is just to arrange | position so that it may connect in parallel. This will be specifically described in the section of the substrate manufacturing method described later.

  In the present embodiment, the thermal via 8 and the heat dissipation layer 9 are embedded in the substrate body 2 in order to reduce the thermal resistance. The thermal via 8 has a columnar shape smaller than the mounting portion 5 of the light emitting element, for example, and is preferably disposed from the non-mounting surface 22 to the heat radiation layer 9 embedded inside. By adopting such an arrangement, the flatness of the entire mounting area 21, particularly the mounting portion 5, 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.

  Next, a preferred embodiment of a light emitting element device having the light emitting element mounting substrate 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. FIG. 4 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. 5 is a cross-sectional view of the light emitting device of FIG. 4 cut along the line Y-Y ′. In addition, in FIG. 4, the state which removed the resin sealing layer shall be shown.

  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 5 of the light-emitting element mounting substrate 1, and a pair of electrodes each have a predetermined wiring conductor layer 4 ( Eight light-emitting elements (for example, LED elements) 11 of a two-wire type that are connected in parallel by wire bonding to the first electrode 41 and the second electrode 42) are provided.

  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 5 of the light emitting element mounting substrate 1 respectively. And fixed to the mounting portion 5 using an adhesive (not shown). That is, the eight light emitting elements 11 are mounted with their directions aligned so that the long side of the lower surface of each light emitting element 11 is parallel to one side of the light emitting element mounting substrate 1.

  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 elements 11 in the light emitting device 10 of the present invention corresponds to the arrangement of the mounting portions 5 in the light emitting element mounting substrate 1. These arrangements are such that the bonding wires 12 do not intersect when 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. Any arrangement may be used, and the arrangement is not limited to that shown in FIG.

  According to the light emitting device 10 of the present invention, since the substrate configured so that the relative external quantum efficiency is 90 or more when the reference external quantum efficiency is 100 is used as the light emitting element mounting substrate 1, Light extraction efficiency is good, and high-luminance 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.

  In manufacturing the light emitting element mounting substrate 1 of the present invention having the above-described structural features, materials and manufacturing methods that are usually used for the light emitting element mounting LTCC substrate can be applied. The light emitting device 10 of the present invention 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 of manufacturing the substrate shown in FIGS. 1 to 3 for mounting the eight 2-wire type light emitting elements so as to be electrically connected in parallel will be described as an example. A method for manufacturing a substrate for use 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, the members used for the manufacture will be described with the same reference numerals as those of the finished product.

(A) Green sheet production process for main body Using a glass ceramic composition containing glass powder and ceramic filler, a green sheet (green sheet for main body) for forming a substrate main body of a light emitting element mounting substrate is produced. . 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. In this step, a green sheet for a frame is also produced in order to form a frame.

(B) Conductive paste layer forming step By forming a conductive paste layer at a predetermined position of 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) Laminating process A plurality of unfired main body members (hereinafter also referred to as green sheets with a conductive paste layer) obtained by forming a conductive paste layer on a green sheet for a main body are stacked and integrated by thermocompression bonding. To obtain a green substrate.

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

  Hereinafter, each step will be further described.

(A) Green sheet manufacturing process for main body A green sheet for main body is prepared by adding a binder, and if necessary, a plasticizer, a dispersing agent, a solvent, etc. to a glass ceramic composition containing glass powder and ceramic filler. 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.

  As a glass powder for producing the green sheet for main bodies, a glass transition point (Tg) of 550 ° C. or higher and 700 ° C. or lower is preferable. When the glass transition point (Tg) is less than 550 ° C., degreasing may be difficult. When the glass transition point (Tg) exceeds 700 ° C., the shrinkage start temperature increases, and the dimensional accuracy may decrease.

  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 the crystallization peak temperature (Tc) exceeds 880 ° C., the dimensional accuracy may be lowered.

As such glass powder, for example, SiO ₂ is 57 mol% or more and 65 mol% or less, B ₂ O ₃ is 13 mol% or more and 18 mol% or less, CaO is 9 mol% or more and 23 mol% or less, and Al ₂ O ₃ is 3 mol% or more and 8 mol% or less. hereinafter, those containing less 0.5 mol% or more 6 mol% of at least one in total selected from _{K 2} O and Na ₂ O are preferred. By using such a thing, 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 mol%, 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 mol%, the glass melting temperature and the glass transition point (Tg) may be excessively high. The content of SiO ₂ is preferably 58 mol% or more, more preferably 59 mol% or more, and particularly preferably 60 mol% or more. The content of SiO ₂ is preferably 64 mol% or less, more preferably 63 mol% or less.

B ₂ O ₃ is a glass network former. If the content of B ₂ O ₃ is less than 13 mol%, there is a possibility that the glass melting temperature or the glass transition point (Tg) becomes too high. On the other hand, when the content of B ₂ O ₃ exceeds 18 mol%, 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 mol% or more, more preferably 15 mol% or more. Further, the content of B ₂ O ₃ is preferably 17 mol% or less, more preferably 16 mol% or less.

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

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

K ₂ O and Na ₂ O are added to lower the glass transition point (Tg). When the total content of K ₂ O and Na ₂ O is less than 0.5 mol%, the glass melting temperature and the glass transition point (Tg) may be excessively high. On the other hand, when the total content of K ₂ O and Na ₂ O exceeds 6 mol%, 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 mol% or more and 5 mol% or less.

  In addition, glass powder 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 a glass transition point (Tg), are satisfy | filled. When other components are contained, the total content is preferably 10 mol% or less.

  The glass powder 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 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 tends to aggregate and difficult to handle, and uniform dispersion becomes difficult. 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 diameter may be adjusted by classification as necessary after pulverization, for example. In the present specification, the particle diameter means a value obtained by a particle diameter measuring apparatus using a laser diffraction / scattering method.

  As the ceramic filler, 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 filler) having a higher refractive index than alumina together with the alumina powder.

The high refractive index filler is a component for improving the reflectance of the sintered body (substrate), and examples thereof include titania filler, zirconia filler, and stabilized zirconia filler. While the refractive index of alumina filler is about 1.8, the refractive index of titania filler is about 2.7, and the refractive index of zirconia filler is about 2.2, which is higher than that of alumina filler. Have. These ceramic fillers preferably have a 50% particle size (D ₅₀ ) of 0.5 μm or more and 4 μm or less.

  By mixing and mixing such glass powder and ceramic filler such that the glass powder is 30 mass% to 50 mass% and the ceramic filler is 50 mass% to 70 mass%, the glass ceramic composition is mixed. A thing is obtained. In addition, a 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. 6, a circular first electrode conductive paste layer 41 is formed in the center of the entire mounting region 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 equal intervals so as to extend inward from the inside. Further, a conductive paste layer 7 for connection via is formed through the upper layer green sheet 23 at a predetermined position of the central portion of the first electrode conductive paste layer 41 and the connecting conductive paste layer 43.

  Further, as shown in FIG. 7, 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 are formed so as to penetrate the green sheet. 7 and a plurality of thermal via conductor paste layers 8 are formed.

  Further, as shown in FIG. 8, 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 is formed with a large number of regions corresponding to a large number of light emitting devices, and these are divided after the final baking step, but in FIGS. 6 to 8, they correspond 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. In addition, as said metal powder, the metal powder which consists of silver powder and silver, platinum, or palladium is used preferably.

(C) Laminating step After stacking the green sheet with conductor paste layer (unfired main body member) obtained in the above step in a predetermined order, and further stacking the frame green sheet on the upper layer green sheet 23, They are integrated by thermocompression bonding. Thus, an unfired substrate is obtained.

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

  For example, degreasing can be performed under a 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, such as Ni / gold plating, which is usually used for protecting a conductor in a light emitting element mounting substrate.

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

Example The light emitting device shown in FIGS. 4 and 5 was manufactured by the method described below.

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 producing these green sheets, first, SiO ₂ was 60.4 mol%, B ₂ O ₃ was 15.6 mol%, Al ₂ O ₃ was 6 mol%, CaO was 15 mol%, K ₂ O was 1 mol%, Na _The raw materials were blended and mixed so that ₂ O would be 2 mol%. 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. This glass was pulverized for 40 hours by an alumina ball mill to produce a glass powder for a substrate 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. 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) as a binder and 5 g of a dispersant (trade name: BYK180, manufactured by Big Chemie) were further 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 (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 α as a solvent so that the solid content is 85 mass%. After being dispersed in 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. 6 so as to be used for the first electrode, the second electrode, and the connection. Are formed, and a through hole having a diameter of 0.15 mm is formed in a portion corresponding to a connection via using a hole puncher, and the conductive paste is filled by a screen printing method to be connected. A via conductor paste layer 7 was formed.

  Further, the conductor paste layer 9 for the heat dissipation layer is formed on the upper surface of the inner layer green sheet 24 by screen printing with the pattern shown in FIG. 7, and holes are formed in the portions corresponding to the thermal via and the connection via. 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. .

  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 with the pattern shown in FIG. 8, and the portions corresponding to the thermal vias and connection vias are formed. Through holes having a diameter of 0.2 mm and a diameter of 0.15 mm are formed using a hole punching machine, and conductive paste is filled by screen printing to form a thermal via conductor paste layer 8 and a connection via conductor paste layer 6. did.

  Each conductive paste layer is mounted on a light-emitting element mounting substrate 1 obtained by firing, and when light-emitting elements such as eight 2-wire type LED elements are mounted and electrically connected by wire bonding, These elements are formed so as to be electrically connected in parallel. Also, the first electrode conductor paste layer 41 and the second electrode conductor paste layer 42 formed on the upper surface (mounting surface) of the upper layer green sheet 23 are formed by firing them. In the annular region between the first electrode 42 and the second electrode 42, eight mounting portions 5 having a square shape of 0.61 mm × 0.61 mm were formed so as to be arranged at substantially equal intervals.

Since each mounting portion 5 has a square shape of 0.61 mm × 0.61 mm, the total area of the eight mounting portions 5 is 2.98 mm ² . Since the area of the mountable region of the light emitting element mounting substrate 1 finally obtained is 10.8 mm ^{2 as} will be described later, the total area of the mounting portion 5 is 28% of the area of the mountable region. It was.

  Next, the green sheets for the main body with conductor paste layers (unfired main body members) produced in this way are superposed in a predetermined order, and further, the green sheet for the frame body is placed on the upper layer green sheet, and the entire mounting whose bottom surface is substantially circular After overlapping so as to form a cavity constituting the region 21, they were integrated by thermocompression bonding. Thus, an unfired substrate was obtained.

  The green substrate thus obtained was degreased by holding at 550 ° C. for 5 hours, and further held and fired at 870 ° C. for 30 minutes to produce a light emitting element mounting substrate 1. The obtained light emitting element mounting substrate 1 has a square shape of 5 mm in length and 5 mm in width and a thickness of 0.5 mm, the height of the frame body 3 is 0.5 mm, and the center of the side of the substrate is The width of the frame 3 at the position was 0.5 mm.

The area of the entire mounting area 21 which is the bottom surface of the cavity surrounded by the frame 3 is 12.6 mm ^2. The first electrode 41 and the second electrode 42 formed in the entire mounting area 21 are provided. The total area was 1.8 mm ² . Therefore, the area of the mountable region excluding the first electrode 41 and the second electrode 42 from the entire mounting region 21 is 10.8 mm ² , and the total area 2.98 mm ² of the eight mounting portions 5 described above is It occupied 28% of the area of this mountable area.

  Next, eight 2-wire type LED elements of the same shape and size were arranged and mounted on the eight mounting portions 5 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).

  With respect to the light-emitting device 10 thus obtained, the external quantum efficiency of the light-emitting device configured in the same manner as in the example except that the entire mounting region 21 was covered with a silver reflecting film having a reflectance of 95% ( As a relative value when the standard external quantum efficiency (100) was 100, an extremely high value of 96 was obtained.

  In addition, the external quantum efficiency measured the total luminous flux using Spectra Corp LED total luminous flux measuring device SOLIDLAMBDA, CCD, LED, MONITOR, PLUS. The integrating sphere used was 6 inches, and R6243 manufactured by Advantest Corporation was used as the voltage / current generator. The LED element was measured by applying 960 mA.

  According to the present invention, in an LTCC substrate for mounting a plurality of two-wire type light emitting elements so as to be electrically connected in parallel, the total area of the mounting portions of the light emitting elements is 10 to 10 times the area of the mountable region. 35% and the relative external quantum efficiency is 90 or more (reference external quantum efficiency is 100). Therefore, when this substrate is used as a light emitting device, the light extraction efficiency is high. It is good and can emit light with high luminance. 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.

DESCRIPTION OF SYMBOLS 1 ... Light emitting element mounting substrate, 2 ... Substrate body, 3 ... Frame, 4 ... Wiring conductor layer, 5 ... Mounting part, 6 ... External electrode terminal, 7 ... Connection via, 8 ... Thermal via, 9 ... Heat dissipation layer, DESCRIPTION OF SYMBOLS 10 ... Light-emitting device, 11 ... Light emitting element, 12 ... Bonding wire, 13 ... Sealing layer, 21 ... Mounting whole area | region, 41 ... 1st electrode, 42 ... 2nd electrode.

Claims (5)

A light emitting element mounting substrate for mounting a plurality of light emitting elements in which a pair of electrodes are connected to the substrate by wire bonding so as to be electrically connected in parallel,
A substrate body comprising a sintered body of a glass ceramic composition containing glass powder and a ceramic filler, and having a mounting surface including a mounting portion on which the light emitting element is mounted;
A wiring conductor layer provided on the mounting surface of the substrate main body so as to be connected to each of the pair of electrodes of the light emitting elements by wire bonding,
The total area of the mounting portions of the plurality of light emitting elements is 10 to 35% of the area of the mounting surface where the light emitting elements can be mounted, and the relative external quantum efficiency is the wiring in the mountable area. A light-emitting element mounting substrate, wherein the external quantum efficiency when the entire mounting area including the conductor layer forming portion is covered with a silver reflective film having a reflectance of 95% is 90 or more.   The wiring conductor layer includes a first electrode disposed in a central portion of the entire mounting region and a second electrode having the same number as the number of the light emitting elements disposed in a peripheral portion of the mounting entire region. The light-emitting element mounting substrate according to claim 1.   The entire mounting area is substantially circular, and the second electrodes are disposed at substantially equal intervals on a circumference surrounding the first electrode disposed in the center of the entire mounting area. Item 3. The light-emitting element mounting substrate according to Item 2.   The said board | substrate main body consists of the sintered compact of the glass-ceramics composition containing the glass powder and the powder of the ceramics which have a refractive index higher than an alumina powder and an alumina, The any one of Claims 1-3 characterized by the above-mentioned. A substrate for mounting a light-emitting element according to 1. The light emitting element mounting substrate according to any one of claims 1 to 4,
A light emitting device comprising: a plurality of light emitting elements mounted on the mounting portion of the light emitting element mounting substrate and having a pair of electrodes connected to the wiring conductor layer by wire bonding.

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