JP2012209310A - Substrate for light-emitting element, and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for light-emitting element which is reduced in warpage amount on the whole and has a recessed part, and a light-emitting device which uses the same and has high reliability in orientation of light, electric connection, etc.SOLUTION: There is provided the substrate for light-emitting element including a substrate body which is made of a sintered body of a first inorganic insulating composition and has a flat main surface, and a frame body which is joined to an upper surface of the substrate body and made of a sintered body of a second inorganic insulating composition, and has a mounting part for light emitting element on a bottom surface of the recessed part formed in the upper surface of the substrate body. A lower surface-side wiring layer is formed by baking metal paste which has a shrinkage start temperature by TMA within a range of +50°C to +150°C of the shrinkage start temperature of the first inorganic insulating composition and a final shrinkage amount by TMA within a range of -75% to +10% of a final shrinkage amount of the first inorganic insulating composition.

Description

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

  2. Description of the Related Art Conventionally, a wiring board for mounting a light emitting element such as a light emitting diode element has a structure in which a wiring conductor layer is disposed on or inside an insulating substrate. As a typical example of this wiring substrate, a concave portion for accommodating a light emitting element is formed on an insulating substrate made of alumina ceramic, and the surface and the inside of the insulating substrate are made of refractory metal powder such as tungsten or molybdenum. There is a wiring board having a configuration in which a plurality of wiring conductor layers are arranged and electrically connected to a light emitting element housed in a recess.

  Further, as an insulating substrate of such a wiring substrate for a light-emitting element, low temperature firing, low dielectric constant, and high electrical conductivity copper and silver wiring are possible, so that glass ceramics containing glass powder and ceramic powder are included. A substrate composed of a low temperature co-fired ceramics (hereinafter referred to as LTCC), which is a sintered body of the composition, has been proposed.

  A ceramic wiring board such as LTCC having the above-mentioned concave portion is usually fired a laminate in which at least a flat green sheet constituting the bottom surface of the concave portion and a green sheet having a through-opening portion constituting the wall portion of the concave portion are laminated. It is manufactured by doing. The wiring conductor layer is formed as an unsintered layer on the surface or inside of each green sheet before the lamination of the green sheets, and is fired at the same time as the green sheets are fired.

  In the ceramic wiring board having the recesses manufactured in this way, there is a problem that the central portion of the flat substrate constituting the bottom surface of the recess is warped due to stress concentration caused by firing shrinkage in the manufacturing process. Was. When such a warped wiring board is used, when the light emitting element is mounted, the mounting position of the light emitting element and the positional deviation of the bonding wire occur, resulting in disconnection, and the result that the light emitting element is mounted tilted. There were problems such as affecting the directivity of light. When this wiring board is mounted on a printed wiring board or the like using solder, warpage of the lower surface center portion of the wiring board causes a gap between the wiring conductor layer on the lower surface side which is an external connection electrode and the solder. There was a problem that a gap was formed, causing disconnection and preventing heat dissipation.

  In order to solve the problem of warping of the ceramic wiring board having the concave portion, for example, in Patent Document 1, a ceramic member having a flat ceramic substrate constituting the concave bottom surface and a through opening constituting the wall portion of the concave portion A method is adopted in which a layer made of a ceramic material having a different shrinkage from the ceramic material constituting the other part is formed near the interface between the two.

  In Patent Document 2 and Patent Document 3, a plurality of green sheets including a thin green sheet having a through-opening portion in a portion corresponding to the bottom surface of the recess are laminated on the flat ceramic substrate constituting the bottom surface of the recess. In this way, a dent is further formed while suppressing the warping of the central portion (bottom surface of the concave portion), and a conductor layer is formed on the entire surface of the flat ceramic substrate or partially so as to fill the dent portion. Thus, the bottom of the recess is flattened.

  Furthermore, in addition to the electrode pattern for external connection on the lower surface of the wiring board, a dummy electrode pattern not to be soldered is provided on the printed wiring board, or a reflective film such as silver formed on the upper surface of the wiring board. Attempts have also been made to suppress warping of a flat substrate by adjusting the shape. However, in any of these methods, the warp of the ceramic wiring board having the recesses could not be sufficiently suppressed.

JP 2007-281108 A JP 2010-186880 A JP 2010-186881 A

  The present invention has been made in order to solve the problem of warping of the substrate for a ceramic light emitting element having the above-mentioned concave portion, and is a substrate for a light emitting element having a concave portion in which the amount of warpage of the entire substrate is reduced. An object of the present invention is to provide a light-emitting device that is highly reliable in terms of directivity of light and electrical connection. Note that in this specification, the light emitting element substrate may be referred to as an element substrate.

The element substrate of the present invention includes a substrate body made of a sintered body of the first inorganic insulating composition, and a sintered body of the second inorganic insulating composition bonded to the upper surface which is one main surface of the substrate body. And a light emitting element mounting portion on a bottom surface of a recess formed with a part of the upper surface of the substrate body as a bottom surface and an inner wall surface of the frame body as a side surface. An element substrate having a lower surface side wiring layer formed by firing a metal paste on a lower surface opposite to the upper surface, wherein the lower surface side wiring layer has a shrinkage start temperature by a thermomechanical analyzer as the first inorganic insulating composition. The final shrinkage by the thermomechanical analyzer is in the range of -75% to + 10% of the final shrinkage of the first inorganic insulating composition. It is formed by firing a certain metal paste. To.
In the present specification, the thermomechanical analyzer is hereinafter referred to as TMA (Thermo-Mechanical Analysis).

  In the element substrate of the present invention, each of the first inorganic insulating composition and the second inorganic insulating composition is a glass ceramic composition containing glass powder and ceramic powder, and the metal paste mainly contains silver. It is preferable to contain a metal powder as a component. The metal paste may include a composite metal powder in which a metal oxide is deposited on the surface of conductive metal particles.

  The light emitting device of the present invention includes the element substrate of the present invention and a light emitting element mounted on the mounting portion of the element substrate.

  In this specification, the main surface on which the light emitting element is mounted by joining the frame of the substrate body is referred to as the upper surface main surface or the upper surface, and the opposite non-mounting main surface is the lower surface main surface. Or it is called the lower surface.

  ADVANTAGE OF THE INVENTION According to this invention, the curvature amount of the whole board | substrate can be reduced in the board | substrate for ceramics light emitting elements which has a recessed part. Further, according to the present invention, by mounting a light emitting element on such an element substrate, a light emitting device with high reliability in light directivity, electrical connection, and the like can be obtained.

1 shows a first embodiment of a light emitting element substrate of the present invention, (a) is a plan view seen from the upper surface side, (b) is a plan view seen from the lower surface side, and (c) is an X in (a). FIG. 2A and 2B show a second embodiment of a substrate for a light-emitting element according to the present invention, where FIG. 5A is a plan view viewed from the upper surface side, and FIG. It is sectional drawing which shows an example of the light-emitting device of this invention using the board | substrate for light emitting elements shown in FIG. It is a top view which shows the light-emitting device of this invention using the board | substrate for light emitting elements shown in FIG. In an Example, it is a graph which shows the TMA curve about silver paste (A) thru | or (K) and a green sheet.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is limited to the following description and is not interpreted.

  The element substrate of the present invention includes a substrate body having a substantially flat main surface made of a sintered body of the first inorganic insulating composition, and a sintered body of the second inorganic insulating composition bonded to the upper surface of the substrate body. And a light emitting element mounting portion on a bottom surface of a recess formed with a part of the upper surface of the substrate body as a bottom surface and an inner wall surface of the frame body as a side surface. An element substrate having a lower surface side wiring layer formed by firing a metal paste on the lower surface of the substrate body, and the lower surface side wiring layer has a shrinkage start temperature by TMA for forming the substrate body. The final shrinkage amount by TMA is −75% to the final shrinkage amount of the first inorganic insulating composition. It is formed of a metal paste in a range of + 10%.

  In addition, the board | substrate with a substantially flat main surface means the board | substrate which has a flat surface of the grade which can recognize that the main surface of an upper surface side and a lower surface side is flat on a visual level. Hereinafter, similarly, the abbreviations indicate the level that can be recognized at the visual level unless otherwise specified.

  According to the present invention, in an element substrate formed of a sintered body of an inorganic insulating composition having a recess and a light emitting element mounting portion on the bottom surface thereof, the shrinkage start temperature by TMA is the shrinkage start temperature of the inorganic insulating composition. With the baking of the metal paste, the bottom surface is baked in a range of + 50 ° C. to + 150 ° C. and the final shrinkage by TMA is in the range of −75% to + 10% with respect to the final shrinkage of the inorganic insulating composition. Since the side wiring layer is formed, the amount of warpage of the element substrate, specifically, the degree of warpage in which the central portion of the substrate warps can be reduced. As a result, the bottom surface of the concave portion is flattened, the positional deviation and inclination of the light emitting element when mounting the light emitting element are reduced, the problem that the directivity of light is different from the design, and the occurrence of disconnection due to the positional deviation of the bonding wire. Can be suppressed. Further, when this element substrate is mounted on a printed wiring board or the like by using solder, problems such as disconnection and deterioration of heat dissipation caused by the warpage of the substrate can be reduced.

  As the sintered body of the first inorganic insulating composition and the sintered body of the second inorganic insulating composition that constitute the base body and the frame, respectively, an aluminum oxide sintered body (alumina ceramic) or an aluminum nitride sintered body is used. Ceramics such as a kneaded body, a mullite sintered body, and LTCC are listed. Since these ceramics have different firing temperatures, the base body and the frame are usually made of the same kind of ceramic. In the present invention, LTCC is preferable as the sintered body of the first and second inorganic insulating compositions from the viewpoints of ease of manufacture, easy processability, economy, and the like. In addition, as long as the sintered bodies of the first and second inorganic insulating compositions are made of the same kind of ceramic, for example, a glass ceramic composition capable of obtaining high bending strength is applied to the base body in LTCC, and the frame body The raw material composition may differ depending on the required characteristics of the base body and the frame, such as applying a glass ceramic composition that places importance on diffuse reflectance.

  When LTCC is selected as the sintered body of the inorganic insulating composition, since a low-temperature firing is possible, the wiring layer such as the lower surface side wiring layer is preferably a metal layer mainly composed of silver. In addition, when alumina ceramic or the like is selected as the sintered body of the inorganic insulating composition, high-temperature firing is required, so the wiring layer includes a metal layer mainly composed of a refractory metal such as tungsten or molybdenum. Become.

  As an embodiment of the element substrate of the present invention, an element substrate in which the sintered body of the first inorganic insulating composition and the sintered body of the second inorganic insulating composition constituting the base body and the frame are both LTCC. Is described below.

  FIG. 1 shows a first embodiment of a light emitting device substrate of the present invention. 1A is a plan view viewed from the upper surface side, FIG. 1B is a plan view viewed from the lower surface side, and FIG. 1C is a cross-sectional view taken along line XX in FIG.

  The element substrate 1 includes a substrate body 2 having a substantially square shape in a top view, which mainly constitutes the element substrate 1. The substrate body 2 has a mounting side surface on which a light emitting element is mounted as an element substrate as an upper surface 21. In this specification, the surface on the non-mounting side opposite to the upper surface 21 is referred to as the lower surface 23 as described above. The thickness, size and the like of the substrate body 2 are not particularly limited, and can be the same as the substrate body of a normal light emitting element wiring substrate. The element substrate 1 further includes a frame body 3 bonded to the upper surface 21 of the substrate body 2. The frame 3 has a peripheral portion of the upper surface 21 of the substrate body 2 so as to form a recess 4 having a substantially circular portion at the center of the upper surface 21 of the substrate body 2 as a bottom surface and a wall surface inside the frame body 3 as a side surface. It is joined to. In the element substrate 1, a mounting portion 22 on which a light emitting element is mounted is provided at a substantially central portion of the bottom surface of the recess 4.

  Here, the side surface of the recess 4 is provided to be inclined with respect to the bottom surface. That is, the frame 3 is shaped so that the upper opening is large and the lower opening is small and the side surface is tapered, and is joined to the peripheral edge of the upper surface 21 of the substrate body 2. The shape of the frame 3 is not limited to this, and the opening 3 may be formed in the same shape at the top and bottom. When such a frame 3 is used, a recess 4 whose side surface is substantially perpendicular to the bottom surface is formed.

  Specific numerical values of the distance between the side surface of the recess 4 and the edge of the light emitting element mounting portion 22 include the output and size of the light emitting element to be mounted, and if necessary, for example, contained in a sealing layer described later Depending on the type of phosphor used, the content thereof, the conversion efficiency, etc., for example, the distance at which the light emitted from the light emitting element is most efficiently emitted in the light extraction direction may be designed as an index. .

  The height of the side surface of the recess 4, that is, the height from the bottom surface of the recess 4 to the upper portion of the frame 3 is particularly limited as long as the light from the mounted light emitting element can be sufficiently reflected in the light extraction direction. Not. Specifically, depending on the design of the light emitting device, for example, the output of the light emitting element to be mounted, the distance from the edge of the light emitting element mounting portion 22, etc., the shape and wavelength conversion of the product on which the light emitting device is mounted From the standpoint of efficiently filling a sealing material containing a phosphor for the purpose, it is preferable that the height is 100 to 500 μm higher than the height of the highest portion of the mounted light emitting element. The height of the frame body 3 is more preferably equal to or less than the height of 450 μm added to the height of the highest portion of the light emitting element, and more preferably equal to or less than the height of 400 μm.

  In the embodiment, both the substrate body 2 and the frame body 3 are configured by LTCC. With respect to the LTCC material constituting the substrate body 2, for example, the bending strength is preferably 250 MPa or more from the viewpoint of suppressing damage or the like when the light emitting element is mounted and thereafter used. The LTCC material constituting the frame body 3 is preferably the same as the material constituting the substrate body 2 in consideration of the adhesion to the substrate body 2.

  Further, a material having diffuse reflectivity can be used as the LTCC material according to the required characteristics of the light emitting device. The LTCC material having diffuse reflectivity is not particularly limited as long as the light extraction efficiency can be improved in a light emitting device using this as a substrate material. Preferably, a light extraction efficiency corresponding to the silver reflective film is obtained. The raw material composition, sintering conditions, and the like of the glass ceramic composition constituting the substrate body 2 and the frame body 3 will be described in the manufacturing method described later.

  In such an element substrate 1, a pair of element connection terminals 5 electrically connected to a pair of electrodes of the light emitting element on the bottom surface of the recess 4 occupying a part of the upper surface 21 of the substrate body 2, The light emitting element is provided so as to face both sides with the mounting portion 22 interposed therebetween. One end portion of the pair of element connection terminals 5 extends in the peripheral direction of the bottom surface of the recess 4, and the frame body 3 is disposed so as to cover the top. The planar shape and arrangement position of the element connection terminal 5 are not limited to those illustrated.

  The film thickness of the element connection terminal 5 is such that the particle size of metal particles in a metal paste usually used for formation is about several μm, and a sufficient amount of metal particles must be present by sintering the metal paste. Therefore, 5 to 15 μm is preferable, and a range of 7 to 12 μm is more preferable.

  Further, in such an element substrate 1, a pair of external connection terminals 6 are provided on the lower surface 23 of the substrate body 2 to be electrically connected by soldering to an external circuit when the light emitting device is formed. A pair of through conductors 7 that electrically connect the element connection terminals 5 and the external connection terminals 6 are provided inside the substrate body 2.

  Further, in order to reduce the thermal resistance of the substrate body 2, a thermal via 8 is provided directly below the light emitting element mounting portion 22 located at the substantially central portion of the bottom surface of the recess 4 so as to penetrate the substrate body 2. The other end of the thermal via 8 is in contact with one of the external connection terminals 6 at the lower surface 23. Therefore, in the element substrate 1 of the first embodiment, one of the pair of external connection terminals 6 has a large area so as to cover the end portion of the thermal via 8 exposed at the substantially central portion of the lower surface 23. The external connection terminal 6 has a small area. The pair of external connection terminals 6 having different electrode areas are disposed asymmetrically with respect to the center line of the lower surface 23. Note that the planar shape and arrangement position of the external connection terminals 6 are not limited to those shown in the figure, but from the viewpoint of heat dissipation, the total electrode area of the pair of external connection terminals 6 is the area of the lower surface 23 of the substrate body 2. 70% or more of the total is preferable.

  The position, shape, size, number, and the like of the thermal vias 8 are not limited to those shown in FIG. 1 and can be adjusted as appropriate. The material constituting the thermal via 8 is not particularly limited as long as it has a heat dissipation property, but a metal material containing silver, specifically, a metal material made of silver, silver and platinum, or silver and palladium is preferable. .

  The constituent material of the element connection terminal 5, the external connection terminal 6, and the through conductor 7 can be used without particular limitation as long as it is the same as that of the wiring conductor used for the element substrate. Specific examples of the constituent material of these wiring conductors include metal materials mainly composed of copper, silver, gold, and the like. Among such metal materials, a metal material composed of silver, silver and platinum, or silver and palladium is preferably used. Hereinafter, the element connection terminal 5, the external connection terminal 6, and the through conductor 7 may be collectively referred to as a “wiring conductor”.

  The wiring conductor is formed by firing a metal paste containing such a metal material powder. As the metal powder other than the metal material powder, a composite metal powder in which a metal oxide is deposited on the surface of conductive metal particles can be used. As the composite metal powder, for example, composite silver powder in which phosphor oxide and yttrium oxide are deposited on the surface of silver particles can be used.

  The composite silver powder can be produced, for example, by the following method. That is, at least one selected from phosphorous acid, phosphite, hypophosphorous acid and hypophosphite is dissolved in an aqueous dispersion slurry of spherical silver powder having an average particle size of 0.1 to 5 μm. After the surface treatment of the silver powder, an aqueous solution of yttrium compound is added, and the pH is adjusted to a range of 7 to 9 with alkali. Next, the silver powder thus surface-treated is filtered, washed and dried, then fired at a temperature of 100 to 700 ° C. in a non-oxidizing atmosphere, and then washed with an acid aqueous solution. The composite silver powder thus obtained provides a metal paste having a low thermal shrinkage rate when fired at a high temperature.

As the metal paste, it is possible to use a paste obtained by adding a vehicle such as ethyl cellulose to the metal powder and, if necessary, other additives, a solvent and the like. Examples of the additive include palladium and dirhodium trioxide. Both palladium and dirhodium trioxide act as silver sintering inhibitors. Although a small amount of rhodium trioxide has an effect of greatly delaying the shrinkage due to firing, an increase in the amount added reduces the adhesion strength with the substrate or impairs printability, so the amount added must be suppressed.
50% particle diameter represented by _{D 50} of the metal powder is preferably 0.5μm or more 10μm or less. In the present specification, the particle diameter refers to a 50% particle diameter, which is a value obtained by a particle diameter measuring apparatus using a laser diffraction / scattering method. Furthermore, the content of the metal powder in the metal paste is preferably adjusted to a range of 80 to 90% by mass. Here, content means the content rate of the metal powder with respect to the whole solid content except a solvent.

  The present invention is characterized in that the external connection terminal 6 which is the lower surface side wiring layer is formed by firing a metal paste having a heat shrinkage characteristic within a predetermined range. Note that, from the viewpoint of ease of manufacture, it is preferable that all of the wiring conductor layers such as the element connection terminal 5, the external connection terminal 6, and the through conductor 7 are formed from one type of metal paste. Therefore, not only the external connection terminals 6 but also the metal paste for forming the element connection terminals 5 and the through conductors 7 have the following heat shrinkage characteristics.

In the present invention, the shrinkage start temperature measured by TMA of the metal paste for forming the external connection terminals 6 and the like is + 50 ° C. to + 150 ° C. of the shrinkage start temperature of the glass ceramic composition for forming the substrate body 2. It is the range. A range of + 50 ° C. to + 100 ° C. is more preferable.
The final shrinkage measured by TMA of the metal paste is in the range of −75% to + 10% with respect to the final shrinkage of the glass ceramic composition for forming the substrate body 2. That is, the final shrinkage amount of the metal paste is in the range of 25% to 110% with the final shrinkage amount of the glass ceramic composition as 100% of the standard. A range of 40% to 100% is more preferable.

  TMA is a method of measuring the deformation of a substance as a function of temperature or time by applying a non-vibrating load such as compression, tension, bending, etc. while changing the temperature of a sample according to a certain program. When deformation of the sample such as thermal expansion or softening of the sample occurs in response to the temperature change, the displacement amount associated with the deformation is measured by the displacement detection unit as the positional change amount of the probe. In the embodiment of the present invention, the TMA measurement is performed using, for example, a trade name TMA-50 manufactured by Shimadzu Corporation, and increasing the temperature at a rate of 10 ° C./min while applying a 10 mg load to the sample. Measure the amount of shrinkage.

  The shrinkage start temperature is a temperature at which the amount of shrinkage reaches a certain value between 3% and 10%, for example, 5% in the heat shrinkage curve obtained by TMA measurement. The heat shrinkage curve obtained by TMA measurement is hereinafter referred to as a TMA curve.

  The shrinkage start temperature and the final shrinkage amount in the TMA curve of the metal paste can be adjusted by the particle size of the metal powder in the metal paste and the content of the metal powder. Moreover, the shrinkage start temperature and the final shrinkage amount can be adjusted by adding additives such as palladium and dirhodium trioxide.

  In the element substrate 1 of the present invention, the warpage amount of the element substrate 1 can be reduced by setting the shrinkage start temperature and the final shrinkage amount of the metal paste for forming the external connection terminals 6 which are the lower wiring layers to the above ranges. . That is, a metal paste having a sufficiently low shrinkage start temperature compared to the glass ceramic composition for forming the substrate body 2 and having a final shrinkage smaller than that of the glass ceramic composition or not so large is used. By forming the external connection terminals 7, the warpage of the element substrate 1 can be reduced, and specifically, the degree of warpage rising to the center can be reduced. More specifically, for example, when the planar size of the substrate body 2 is 5 mm × 5 mm, the amount of warping of the central portion can be reduced to 10 μm or less. As a result, the bottom surface of the concave portion 4 is flattened, the positional deviation and inclination of the light emitting element when mounting the light emitting element are reduced, the problem that the directivity of light is different from the design, and the disconnection due to the positional deviation of the bonding wire Can be suppressed. Further, when the element substrate 1 is mounted on a printed wiring board or the like by using solder, problems such as disconnection and deterioration of heat dissipation, which are caused by the warpage of the board, can be reduced.

  When the shrinkage start temperature of the metal paste for forming the external connection terminals 6 is less than + 50 ° C. based on the shrinkage start temperature of the glass ceramic composition, as described later, an unfired wiring layer made of this metal paste When the element substrate 1 is manufactured by co-firing a green sheet laminate made of the glass ceramic composition having the above, the timing at which the metal paste shrinks is not sufficiently late compared with that of the glass ceramic composition. The metal paste starts to contract before a sufficient time has elapsed after the glass ceramic composition starts to contract. Therefore, the element substrate 1 is warped such that the central portion of the substrate body 2 is warped.

  When the shrinkage start temperature of the metal paste is higher than + 150 ° C. relative to the shrinkage start temperature of the glass ceramic composition, the metal paste shrinks too late, so it may be deformed into a concave shape after firing, The metal paste may be insufficiently sintered when co-fired with the glass ceramic composition.

  When the final shrinkage of the metal paste is smaller than 75% of the final shrinkage of the glass ceramic composition, that is, when the final shrinkage of the metal paste is less than 25% of the final shrinkage of the glass ceramic composition. Since the shrinkage of the metal paste is too small, it deforms into a concave shape, or the sintering of the metal conductor progresses too much, so that the glass component contained in the substrate body 2 oozes out on the metal surface and hinders solder mountability. To do.

  When the final shrinkage amount of the metal paste is larger than 10% with respect to the final shrinkage amount of the glass ceramic composition, that is, when the final shrinkage amount of the metal paste is more than 110% of the final shrinkage amount of the glass ceramic composition. In other words, since the shrinkage amount of the metal paste is too large, the center portion of the substrate body 2 of the element substrate 1 is warped.

  The thickness of the external connection terminal 6 formed by firing such a metal paste is such that the particle size of the metal particles in the metal paste is usually several μm, and a sufficient amount of metal particles are sintered by sintering the metal paste. 5 to 15 μm is preferable, and a range of 7 to 12 μm is more preferable.

  Note that a conductive protective layer (not shown) is provided on the element connection terminals 5 and the external connection terminals 6 in order to protect these layers made of a metal material such as silver from oxidation and sulfurization and to impart conductivity. ) Can be formed. The conductive protective layer is not particularly limited as long as it is a conductive material having a function of protecting the layer made of the metal material. Specific examples include a nickel plating layer, a nickel / gold plating layer, a silver plating layer, a nickel / silver plating layer, a chromium plating layer, and the like, and bonding wires and other connection materials used for connection with electrodes of light emitting elements to be described later The nickel / gold plating layer is preferable from the standpoint of obtaining good bonding. The thickness of the conductive protective layer is preferably 2 to 20 μm for the nickel plating layer and 0.1 to 1.0 μm for the gold plating layer.

  Although not shown in FIG. 1, in the element substrate 1 of the embodiment, in order to increase the light extraction efficiency from the mounted light emitting element, silver, for example, is mainly used in the widest possible range of the bottom surface of the recess 4. The reflective film as a component may be formed so as not to be electrically connected to the pair of element connection terminals 5, and an overcoat glass layer covering the whole including the edge of the reflective film is further formed thereon. May be.

  Next, as a second embodiment of the element substrate of the present invention, in order to mount a plurality of, for example, 15 two-wire type light emitting elements in rows and columns and connect the light emitting elements in parallel. The element substrate will be described.

  FIG. 2A is a plan view of the element substrate according to the second embodiment as viewed from the upper surface side, and FIG. 2B is a plan view of the element substrate as viewed from the lower surface side.

  The element substrate 1 has a substantially flat plate-like substrate body 2 having a substantially square planar shape, and a frame 3 is joined to a peripheral portion of an upper surface 21 thereof, and a recess having a bottom portion at the center of the substrate body 2. 4 is formed.

  In the element substrate 1, fifteen mounting portions 22 on which two-wire type light emitting elements are mounted are provided on the bottom surface of the recess 4, arranged in three horizontal rows and five vertical columns. These mounting units are disposed between the mounting unit group 22a in the first row and the mounting unit group 22b in the second row, and between the mounting unit group 22b in the second row and the mounting unit group 22c in the third row. Two element-connecting intermediate terminals 51 that are electrically connected to the light-emitting elements mounted on the portion 22 are provided. Further, peripheral terminals 52 for element connection are respectively provided on the outer peripheral side of the first row mounting portion group 22a and the outer peripheral side of the third row mounting portion group 22c. The two intermediate terminals 51 constitute an anode side electrode and a cathode side electrode, respectively, and the two peripheral terminals 52 also constitute an anode side electrode and a cathode side electrode, respectively. The anode side electrode and the cathode side electrode are opposed to each other with the mounting portion group in each row interposed therebetween, and are alternately arranged.

  In addition, external electrode terminals 6 on the anode side and the cathode side are provided on the lower surface of the substrate body 2. The anode-side external electrode terminal 6 is electrically connected to the anode-side intermediate terminal 51 and the anode-side peripheral terminal 52 provided on the upper surface of the substrate body 2 through a through conductor 7 formed inside the substrate body 2 or the like. Connected. Similarly, the external electrode terminal 6 on the cathode side is electrically connected to the intermediate terminal 51 on the cathode side and the peripheral terminal 52 on the cathode side through a through conductor formed inside the substrate body 2 and the like.

  Further, thermal vias (not shown) are embedded in the substrate body 2 in order to reduce thermal resistance. The thermal via is, for example, a columnar shape smaller than the mounting portion 22 of the light emitting element, and can be arranged from the upper surface of the substrate body 2 to the external electrode terminal 6 that also functions as a heat dissipation layer.

  Also in the second embodiment, as in the first embodiment, the external electrode terminal 6 is formed by firing a metal paste having the following shrinkage characteristics. That is, the shrinkage start temperature by TMA is in the range of + 50 ° C. to + 150 ° C. with respect to the shrinkage start temperature of the glass ceramic composition constituting the substrate body 2, and the final shrinkage amount by TMA is the glass ceramic composition. The external electrode terminal 6 is formed by firing a metal paste in the range of −75% to + 10% with respect to the final shrinkage amount.

  Also in the second embodiment, the warpage amount of the element substrate can be reduced by setting the shrinkage start temperature and the final shrinkage amount of the metal paste for forming the external connection terminals 6 which are the lower surface side wiring layers within the above ranges.

  Although the embodiment of the element substrate of the present invention has been described above, a light emitting device can be manufactured by mounting a light emitting element such as a light emitting diode element on the mounting portion 22 using the element substrate 1.

  As shown in FIG. 3, the light emitting device 10 of the first embodiment having the element substrate 1 shown in FIG. 1 has a silicone die-bonding agent on the mounting portion 22 positioned substantially at the center of the bottom surface of the recess 4 of the element substrate 1. A light-emitting element 11 such as a light-emitting diode element is mounted by a die-bonding agent 14 or the like, and a pair of electrodes (not shown) is connected to each of a pair of element connection terminals 5 by a bonding wire 12. The light emitting device 10 further includes a sealing layer 13 provided so as to fill the concave portion 4 while covering the light emitting element 11 and the bonding wire 12 arranged as described above on the bottom surface of the concave portion 4. . In addition, the sealing material which comprises the sealing layer 13 may contain the fluorescent substance normally used for the sealing layer of a light-emitting device as needed.

  Further, in the light emitting device 10 of the second embodiment configured using the element substrate 1 shown in FIG. 2, as shown in FIG. 4, it is arranged in 3 rows and 5 columns on the bottom surface of the recess 4 of the element substrate 1. The light emitting elements 11 are mounted on the 15 mounting portions 22 provided. Then, the 15 light emitting elements 11 arranged in 3 rows and 5 columns in this way are connected to the intermediate terminal 51 and the peripheral terminal 52 by bonding wires 12 as shown below. That is, among the light emitting elements 11, each of the five light emitting elements 11 a and 11 c mounted on the first row mounting portion group 22 a and the third row mounting portion group 22 c has one of the electrodes (not shown) as the bonding wire 12. Is connected to the peripheral terminal 52, and the other is connected to the opposing intermediate terminal 51 by the bonding wire 12. Further, the five light emitting elements 11b mounted on the mounting unit group 22b in the second row have one electrode connected to one of the two intermediate terminals 51 by the bonding wire 12 and the other connected to the bonding wire 12. Is connected to the other intermediate terminal 51. Thus, the 15 light emitting elements 11 arranged in 3 rows and 5 columns are wire-bonded so as to be connected in parallel.

Here, in the light emitting device 10 of the second embodiment, the intermediate terminal 51 is connected to the external connection terminal 6 by a through conductor. However, if the intermediate terminal 51 is not provided with the through conductor, the intermediate terminal 51 is external. The 15 light-emitting elements 11 that are electrically insulated from the connection terminal 6 and arranged in 3 rows and 5 columns have 5 columns in which the three light-emitting elements 11 are connected in series from the peripheral terminal 52 and connected in series. The light emitting element groups can be electrically connected in parallel.
In the light emitting device 10 of the second embodiment, the other parts are configured in the same manner as the light emitting device 10 of the first embodiment, and thus the description thereof is omitted.

  Since the light emitting device 10 of the first embodiment and the second embodiment of the present invention configured as described above has the element substrate 1 of the present invention in which the amount of warpage of the substrate itself is reduced, the light emitting element 11 is reduced, and problems such as the difference in the light directivity from the design and the occurrence of disconnection due to the positional deviation of the bonding wire 12 are suppressed. Further, when the light emitting device 10 is further mounted on a printed wiring board or the like by using solder, problems such as disconnection or deterioration of heat dissipation caused by the warpage of the board can be reduced. Such a light emitting device 10 of the present invention can be suitably used as a backlight such as a liquid crystal display of a mobile phone, a personal computer, or a flat television, for example, illumination for automobiles or decoration, general illumination, and other light sources.

  The embodiment of the element substrate 1 and the light emitting device 10 using the element substrate 1 of the present invention has been described above by way of example, but the element substrate 1 and the light emitting device 10 of the present invention are not limited to these. As long as it does not contradict the spirit of the present invention, the configuration can be changed as necessary.

  Next, the manufacturing method of the element substrate of the present invention will be described below by taking the manufacturing method of the element substrate 1 shown in FIG. 1 as an example. In the following description, members used for manufacturing will be described with the same reference numerals as those of the finished product.

(A) Green sheet manufacturing process First, a substantially flat substrate body green sheet and frame body green sheet are manufactured. These green sheets are prepared by adding a binder to a glass ceramic composition containing glass powder and ceramic powder, and if necessary, adding a plasticizer, a solvent, etc., to form a slurry, which is then formed into a sheet by the doctor blade method, etc. And can be produced by drying.

  The glass powder is not necessarily limited, but the glass transition point represented by Tg is preferably 550 ° C. or higher and 700 ° C. or lower. When the glass transition point is lower than 550 ° C., degreasing described later may be difficult. On the other hand, when the glass transition point exceeds 700 ° C., the shrinkage start temperature becomes too high, and the dimensional accuracy may be lowered.

  Moreover, it is preferable that a crystal | crystallization precipitates when it bakes at 800 degreeC or more and 930 degrees C or less. If crystals do not precipitate, sufficient mechanical strength may not be obtained. Further, the crystallization peak temperature measured by DTA (Differential Thermal Analysis, differential thermal analysis) and represented by Tc is preferably 880 ° C. or lower. When the crystallization peak temperature exceeds 880 ° C., the dimensional accuracy may decrease.

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. With such a composition, the flatness of the upper and lower surfaces of the substrate body can be easily improved.

Here, SiO ₂ becomes 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 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 point or the glass transition point becomes excessively 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 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 glass transition point. 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. 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 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.

  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, are satisfy | filled. When other components are contained, the total content is preferably 10 mol% or less.

  The glass powder can be obtained by producing glass having the glass composition as described above by a melting method and by a dry pulverization method or a wet pulverization method. In the case of the wet pulverization method, it is preferable to use water as a solvent. The pulverization is performed using a pulverizer such as a roll mill, a ball mill, or a jet mill.

  The 50% particle size of the glass powder is preferably 0.5 μm or more and 2 μm or less. When the 50% particle size of the glass powder is less than 0.5 μm, the glass powder is likely to aggregate and not only becomes difficult to handle, but also difficult to disperse uniformly. 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. Adjustment of the particle size is performed by classification as necessary after pulverization, for example.

  As the ceramic powder, those conventionally used for the production of LTCC substrates can be used without particular limitation. For example, alumina powder, zirconia powder, or a mixture of alumina powder and zirconia powder is suitably used. The 50% particle size of the ceramic powder is preferably 0.5 μm or more and 4 μm or less.

  A glass ceramic composition is prepared by mixing and mixing such ceramic powder and the glass 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. Get. Moreover, a slurry is obtained by adding a binder and, if necessary, a plasticizer, a dispersant, a solvent, and the like to the glass ceramic composition.

  As the binder, for example, polyvinyl butyral, 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, for example, aromatic organic solvents such as toluene and xylene, and alcohol organic solvents such as butanol can be used. Furthermore, a dispersing agent and a leveling agent can also be used.

  A green sheet can be produced by forming this slurry into a sheet by a doctor blade method or the like and drying it. Then, the green sheet for the substrate body is formed by punching a predetermined position of the green sheet thus obtained using a punching die or a punching machine to form a through hole for interlayer connection and a through hole for thermal via. To manufacture. Further, in the green sheet, the center portion is cut into a predetermined shape such as a substantially circular shape to produce a frame green sheet.

(B) Metal paste layer forming step The metal paste is filled in the through holes for interlayer connection and the through holes for thermal vias formed at predetermined positions of the green sheet for substrate main body obtained in the step (A). Then, a through conductor metal paste layer 7 and a thermal via metal paste layer 8 that penetrate the substrate main body green sheet from the front surface to the back surface are formed. In addition, a pair of element connecting terminal metal paste layers 5 are formed so as to cover the through conductor paste layer 7 on the upper surface 21 of the upper surface 21 of the substrate body green sheet so as to cover the through conductor paste layer 7. Then, a pair of external connection terminal metal paste layers 6 that are electrically connected to the through conductor metal paste layer 7 are formed. One of the pair of external connection terminal metal paste layers 6 is formed in contact with the lower end portion of the thermal via metal paste layer 8. Thus, a green sheet for a substrate body with a metal paste layer is obtained. Although not shown, alignment marks for stacking can be formed on the green sheet for the substrate body.

  As a method of forming the element connection terminal metal paste layer 5, the external connection terminal metal paste layer 6, the through conductor metal paste layer 7 and the thermal via metal paste layer 8, the metal paste is applied and filled by screen printing. A method is mentioned. The film thicknesses of the element connection terminal metal paste layer 5 and the external connection terminal metal paste layer 6 are adjusted so that the finally obtained element connection terminals 5 and external connection terminals 6 have predetermined film thicknesses. The

  As the metal paste, a paste obtained by adding a vehicle such as ethyl cellulose to a metal powder mainly composed of copper, silver, gold or the like, a solvent, an additive or the like as necessary is used. The metal powder is preferably a metal powder made of silver, or a metal powder made of silver and platinum or palladium. A composite silver powder in which phosphorous oxide and yttrium oxide are deposited on the surface of spherical silver particles can also be used.

  And this metal paste has the heat shrink characteristic of the predetermined range mentioned above. That is, the shrinkage start temperature measured by TMA is in the range of + 50 ° C. to + 150 ° C. with respect to the shrinkage start temperature of the substrate body green sheet for forming the substrate body, and the final shrinkage amount is the substrate body. A metal paste in the range of −75% to + 10% with respect to the final shrinkage of the green sheet for use is used.

(C) Lamination For the frame body obtained in the step (A) on the surface of the green sheet for substrate main body with metal paste layer obtained in the step (B) on which the element connection terminal metal paste layer 5 is formed. The green sheets are stacked while being aligned, and are integrated by heating and pressing to obtain an unfired element substrate 1.

(D) Firing step After the step (C), after the unbaked element substrate 1 obtained, after degreasing to decompose and remove binders such as resin contained in the green sheet as necessary, In order to sinter the glass ceramic composition or the like, it is fired at a temperature of 800 to 930 ° C.

  For example, the degreasing is preferably performed under the condition of holding at a temperature of 500 ° C. or more and 600 ° C. or less for 1 hour or more and 10 hours or less. When the degreasing temperature is less than 500 ° C. or the degreasing time is less than 1 hour, the binder or the like may not be sufficiently removed. If the degreasing temperature is about 600 ° C. and the degreasing time is about 10 hours, the binder and the like can be sufficiently removed, and if it exceeds this, the productivity is lowered.

  In the firing, the time is appropriately adjusted in a temperature range of 800 ° C. to 930 ° C. in consideration of obtaining a dense structure of the substrate and productivity. Specifically, it is preferably held at a temperature of 850 ° C. or higher and 900 ° C. or lower for 20 minutes or longer and 60 minutes or shorter, particularly preferably at a temperature of 860 ° C. or higher and 880 ° C. or lower for 20 minutes or longer and 60 minutes or shorter. If the firing temperature is less than 800 ° C., a substrate having a dense structure may not be obtained. On the other hand, when the firing temperature exceeds 930 ° C., productivity and the like may be lowered due to deformation of the substrate. Moreover, when the metal paste containing the metal powder which has silver as a main component is used and a calcination temperature exceeds 880 degreeC, there exists a possibility that a metal paste may soften too much and it may become impossible to maintain a predetermined shape.

  In this way, the unsintered element substrate 1 is fired to obtain the element substrate 1. After firing, gold plating is applied so as to cover the entire element connection terminals 5 and external connection terminals 6 as necessary. In general, a conductive protective layer used for protecting a conductor in a light emitting element substrate such as nickel / gold plating can be formed. Note that the element substrate 1 of the present invention has a process of producing a multi-piece connecting board, which is usually used when producing a wiring board for a light-emitting element, and dividing the individual board 1 according to its size. You may produce by the method of producing a wiring board.

  As mentioned above, although the manufacturing method was demonstrated about an example of embodiment of the element substrate of this invention, the green sheet for base | substrate bodies, the green sheet for frames, etc. do not necessarily need to consist of a single green sheet, and several sheets A laminate of green sheets may also be used. Further, the order of forming each part can be changed as appropriate as long as the element substrate can be manufactured.

  Hereinafter, specific examples of the present invention will be described.

As shown below, silver pastes (A) to (H) for forming a wiring conductor were prepared. Moreover, the green sheet (glass ceramic composition) for board | substrate main body formation and frame body formation was produced.
(Preparation of silver paste)
First, the following silver powders (a) to (f) and composite silver powder (g) were prepared.
Silver powder (a): S400-2 manufactured by Daiken Chemical Industry Co., Ltd.
(D ₅₀ 2.0 μm, particle shape spherical)
Silver powder (b): AG-2-1C manufactured by DOWA Electronics
(D ₅₀ 0.8 μm, particle shape spherical)
Silver powder (c): AG-3-8F manufactured by DOWA Electronics
(D ₅₀ 1.4 μm, particle shape spherical)
Silver powder (d): F-1 manufactured by Daiken Chemical Industry Co., Ltd.
(D ₅₀ 3.0 μm, particle shape spherical)
Silver powder (e): FA-D-2 manufactured by DOWA Electronics
(D ₅₀ 5.5 μm, particle shape flat)
Silver powder (f): S550 manufactured by Daiken Chemical Industry Co., Ltd.
(D ₅₀ 5.0 μm, particle shape flat)
Composite silver powder (g): Composite silver powder obtained by depositing yttrium trioxide (Y ₂ O ₃ ) on the surface of S550 (D ₅₀ 5.0 μm, particle shape flat) manufactured by Daiken Chemical Industry Co., Ltd.

These silver powders (a) to (f) and composite silver powder (g) were blended so as to have the composition shown in Table 1 to prepare silver pastes (A) to (K). For the silver pastes (A) to (F), as shown in Table 1, the total amount of silver powder is 100 parts by mass, and ethyl cellulose as a vehicle has a silver powder: vehicle mass ratio of 90:10. Blended into For silver pastes (G) to (K), a total of 100 parts by mass of silver powder was blended with the additives shown in Table 1 in an amount (parts by mass) shown in the same table, and ethyl cellulose as a vehicle was added to silver powder. : The vehicle mass ratio was 90:10.
Next, these mixtures were dispersed in α-terpineol as a solvent so as to have a solid content ratio (mass%) shown in Table 1, and then kneaded in a porcelain mortar for 1 hour, and further three times with three rolls. Dispersion was performed to obtain silver pastes (A) to (K).

(Production of green sheets)
The raw materials were adjusted so that 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%, and Na ₂ O was 2 mol%. After mixing and mixing, this raw material mixture was put in a platinum crucible and melted at 1600 ° C. for 60 minutes, and then the molten glass was poured out and cooled. This glass was pulverized with an alumina ball mill for 40 hours to produce a glass powder for a substrate. Note that ethyl alcohol was used as a solvent for grinding.

This glass powder is 35% by mass, alumina filler (manufactured by Showa Denko KK, trade name: AL-45
H) is 40% by mass, zirconia filler (manufactured by Daiichi rare element chemical industry, trade name: HSY-3)
A glass ceramic composition for a substrate was prepared by blending and mixing such that FJ) was 25% by mass.

  To 50 g of this glass ceramic composition for substrates, 15 g of an organic solvent (mixed with toluene, xylene, 2-propanol, 2-butanol at a mass ratio of 4: 2: 2: 1), a plasticizer (di-2-phthalate) 2.5 g of ethylhexyl), 5 g of polyvinyl butyral (trade name: PVK # 3000K) as a binder, and 0.5 g of a dispersant (trade name: BYK180, manufactured by BYK Chemie) are mixed and mixed to prepare a slurry. Prepared.

  This slurry was applied onto a PET film by a doctor blade method, dried, and then cut to produce green sheets for a substrate body and a frame having a thickness of 0.1 mm.

  Next, TMA measurement was performed on the thus obtained green sheet (glass ceramic composition) and the silver pastes (A) to (K). The measurement was performed using TMA-50 manufactured by Shimadzu Corporation. The temperature was increased at a rate of 10 ° C./min while applying a load of 10 mg to the samples prepared from the silver pastes (A) to (K) and the green sheet, and the shrinkage curves at that time were measured.

  The silver paste samples were prepared by heating and drying the silver pastes (A) to (K) at 250 ° C. for 1 hour, respectively, and then aggregating them with an alumina mortar, followed by pressing with a cylindrical mold having a diameter of 5 mm. A disc-shaped sample having a thickness of 1 mm was prepared. A green sheet sample was prepared by laminating a green sheet having a thickness of 0.1 mm as described above to a thickness of 1 mm and then punching it into a disk shape having a diameter of 5 mm.

  The TMA curves of the silver pastes (A) to (K) and the green sheet thus measured are shown in FIG.

  Next, from the TMA curve shown in FIG. 5, the shrinkage start temperatures at which the shrinkage amounts of the silver pastes (A) to (K) reach 5% are obtained, and the shrinkage start temperatures of the green sheets whose values are the reference values ( (+ T ° C; t is a positive number, the same shall apply hereinafter) or lower (-t ° C). Further, the final shrinkage (μm) of the silver pastes (A) to (K) was determined from the TMA curve. Then, the ratio (%) of these values with the final shrinkage (μm) of the green sheet as the reference (100%) was obtained. Since the left vertical axis in the TMA curve represents the initial state as 0 and the contraction as a negative amount, the final contraction amount (μm) was obtained as an absolute value of the value on the vertical axis. These results are shown in Table 2.

  From the results in Table 2, the silver pastes (G), (H), (I) and (J) all have a shrinkage start temperature by TMA of + 50 ° C. to + 150 ° C. relative to the shrinkage start temperature of the green sheet for substrate formation. And the final shrinkage is in the range of -75% to + 10% of the final shrinkage of the green sheet, that is, in the range of 25% to + 110% of the final shrinkage of the green sheet. It turned out that it is suitable as a metal paste for forming the external connection terminal which is a lower surface side wiring layer in an element substrate.

  On the other hand, in silver pastes (A) to (F) and (K), the shrinkage start temperature by TMA is not in the range of + 50 ° C. to + 150 ° C. relative to the shrinkage start temperature of the green sheet for substrate formation. Further, since the final shrinkage amount is not in the range of −75% to + 10% from the final shrinkage amount of the green sheet, it was found that the final shrinkage amount is not suitable as a metal paste for forming the external connection terminal in the element substrate of the present invention. .

  Next, the substrate body 2 was laminated using the above-described green sheet so that the thickness of the substrate body 2 was 0.5 mm, and an element substrate was manufactured using silver pastes (A) to (K) as metal pastes. A through hole is formed in a portion corresponding to the green through conductor of the green sheet using a hole punch, and then the silver paste (A) to (K) is filled into the through hole by a screen printing method. While forming the metal paste layer for penetration conductors, the metal paste layer for connection terminals and the metal paste layer for external electrode terminals were each formed, and the green sheet for board bodies with a metal paste layer was obtained.

  Next, a green sheet for a frame body having a circular opening having a thickness of 0.5 mm is overlaid on the green sheet for a substrate main body with a metal paste layer, and heated and pressed to be integrated to form an unfired element. A substrate was obtained. The circular opening has a size of 4.4 mm after firing, and the center of the circle is arranged at the center of the substrate body 2 in the element substrate whose outer shape shown in FIG. 1 is 5 mm long and 5 mm wide. Laminated while aligning. Subsequently, degreasing was carried out by holding at 550 ° C. for 5 hours, and further firing was carried out by holding at 870 ° C. for 30 minutes to produce an element substrate.

  About the obtained element substrate, the XX plane of FIG. 1 was divided | segmented using the dicing machine, the fracture surface was observed, and the curvature amount of the upper surface of the board | substrate body 2 was measured with the length measuring microscope. The results are shown in Table 2.

  As can be seen from Table 2, the substrate obtained by using the silver pastes (G), (H), (I) and (J) to form wirings such as external electrode terminals has a warpage amount of 10 μm or less. It is small and the flatness of the element substrate is maintained.

  On the other hand, the substrate on which the wirings such as the external electrode terminals are formed using the silver pastes (A) to (F) and (K) has a large warp amount of 20 μm or more, and the light emitting element is mounted. This causes problems such as the occurrence of misalignment and bonding wire misalignment, and the influence of the directivity of light because the light emitting element is mounted at an angle.

  According to the present invention, in an element substrate having a recess and mounting a light emitting element on its bottom surface, the degree of warpage of the substrate itself can be reduced. In the light emitting device of the present invention, the element substrate of the present invention in which the warpage is reduced in this manner reduces the positional deviation and inclination of the light emitting element, and the light directivity is different from the design, and the position of the bonding wire. It is a light emitting device in which problems such as occurrence of disconnection due to deviation are suppressed. Further, when this light emitting device is further mounted on a printed wiring board or the like using solder, problems such as disconnection and deterioration of heat dissipation, which are caused by the warpage of the board, can be reduced. Such a light-emitting device of the present invention can be suitably used as a backlight for a liquid crystal display of a mobile phone, a personal computer, or a flat television, for example, illumination for automobiles or decoration, general illumination, and other light sources.

DESCRIPTION OF SYMBOLS 1 ... Element board | substrate, 2 ... Board | substrate body, 3 ... Frame body, 4 ... Recessed part, 5 ... Element connection terminal, 6 ... External connection terminal, 7 ... Through-conductor, 8 ... Thermal via, 10 ... Light-emitting device, 11 ... Light-emitting element , 12 ... bonding wires, 13 ... sealing layer.

Claims (4)

A substrate body made of a sintered body of the first inorganic insulating composition; and a frame body made of a sintered body of the second inorganic insulating composition bonded to the upper surface which is one main surface of the substrate body. A light emitting element mounting portion on the bottom surface of the recess formed with a part of the top surface of the substrate body as a bottom surface and the inner wall surface of the frame body as a side surface, and a bottom surface opposite to the top surface of the substrate body A substrate for a light emitting device having a lower surface side wiring layer formed by firing a metal paste,
The lower wiring layer has a shrinkage start temperature by the thermomechanical analyzer in the range of + 50 ° C. to + 150 ° C. with respect to the shrinkage start temperature of the first inorganic insulating composition, and a final shrinkage amount by the thermomechanical analyzer Is formed by firing a metal paste in the range of −75% to + 10% of the final shrinkage of the first inorganic insulating composition.   The first inorganic insulating composition and the second inorganic insulating composition are both glass ceramic compositions containing glass powder and ceramic powder, and the metal paste contains metal powder mainly composed of silver. The substrate for a light-emitting element according to claim 1.   The light emitting element substrate according to claim 1, wherein the metal paste contains a composite metal powder in which a metal oxide is deposited on the surface of conductive metal particles. The substrate for a light emitting device according to any one of claims 1 to 3,
And a light emitting device mounted on the mounting portion of the light emitting device substrate.

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