JP2012099534A - Element substrate and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an element substrate which is free of shorting defects when joined by soldering with a component mounting circuit board and thus exhibits improved strength of solder joints and a highly reliable light-emitting device using such an element substrate.SOLUTION: The element substrate comprises a substrate body 2 which is composed of an inorganic insulating material and part of which has a mounting plane serving as a mounting portion on which a light-emitting device 11 will be mounted and a wiring conductor which is formed on the surface and inside of the substrate body so as to electrically connects electrodes of the light-emitting device to an external circuit and part of which is disposed as a plurality of external connection terminals 5 on a non-mounting plane, or a surface on the opposite side of the mounting plane, the external connection terminals being joined by soldering to wiring circuits of the circuit board. On the non-mounting plane of the substrate body, in a region between one of the external connection terminals and another external connection terminal opposed to that external connection terminal, is formed a solder adhesion prevention layer 6 which is composed of an inorganic insulating material containing glass as its primary ingredient and has a surface roughness Ra of 0.03 μm or less.

Description

  The present invention relates to an element substrate for a light emitting element (hereinafter referred to as an element substrate) and a light emitting device, and in particular, a short circuit failure at the time of solder bonding to an external circuit board for mounting (hereinafter referred to as a circuit board). The present invention relates to a non-element substrate and a light-emitting device using the element substrate.

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

  Conventionally, ceramic substrates such as alumina substrates have been used as element substrates. Further, a low temperature co-fired ceramic (hereinafter referred to as LTCC) substrate has been proposed as an element substrate having a higher reflectance than a ceramic substrate such as an alumina substrate. The LTCC substrate is made of a sintered body of ceramic powder such as alumina powder and glass, and has a large refractive index difference between the glass and ceramic, and a large proportion of the interface between the two facing the light incident direction. Since the particle size (thickness) of the powder is larger than the wavelength used, high reflectance can be obtained. Further, the light from the light emitting element can be used efficiently, and as a result, the heat generation amount can be reduced.

  Such an element substrate usually has a plurality of (for example, a pair of anode side and cathode side) external parts for connecting the light emitting element to an external circuit on the surface opposite to the surface on which the light emitting element is mounted. It has connection terminals, and these external connection terminals and a wiring circuit formed on the surface of an external circuit board are joined via solder (so-called soldering, hereinafter referred to as solder joining) to be electrically connected. Connect and use it mounted on a circuit board.

  However, in such a mounting structure, there is a possibility that the solder that has flowed during solder bonding flows between the external connection terminals of the element substrate and short-circuits the external connection terminals. For this reason, it is difficult to reduce the distance between the external connection terminals, that is, the interval (hereinafter referred to as the interval) beyond a certain limit. There was a problem that the solder joint strength was lowered due to the reduction of the electrode area.

  For example, when a printed wiring board in which a wiring circuit is formed by patterning copper foil using an epoxy resin as an insulating base material is used as the circuit board, the thickness of the solder layer that joins the wiring circuit and the external connection terminal of the element substrate The distance between the anode-side and cathode-side external connection terminals of the element substrate was required to be 200 to 300 μm. When the interval between the external connection terminals is less than 200 μm, the solder that has flowed in between the external connection terminals becomes a bridge, which may cause a short circuit between the external connection terminals. Also, if an interval exceeding 300 μm is set between the external connection terminals, the electrode area of the external connection terminals cannot be made sufficiently large, and there is a case where sufficient bonding strength by soldering with the circuit board for mounting cannot be secured. .

  In particular, in the element substrate, when providing thermal vias for heat dissipation inside the substrate, the pair of external connection terminals on the anode side and the cathode side have a plane shape (pattern) that is asymmetric with respect to the center line of the non-mounting surface. However, if the interval between the external connection terminals is 200 μm or more in such a configuration, the electrode area of one external connection terminal becomes too small, and sufficient solder joint strength between the circuit board and the wiring circuit is obtained. Could not be secured. Therefore, there is a demand for an element substrate that does not cause a short circuit between the external connection terminals even when the interval between the external connection terminals of the element substrate is significantly narrower than before, for example, 100 to 150 μm.

  In addition, as a terminal structure that does not cause cracks in the ceramic around the electrode pad of the ceramic circuit board, the electrode pad and the glass protective film are covered with a glass protective film so that the two layers of the electrode pad and the glass protective film overlap, and the electrode There has been proposed a module in which the outer peripheral portion of the pad is shaped so as to sink into the circuit board side along the back surface of the glass protective film (see, for example, Patent Document 1).

  However, in the ceramic circuit module described in Patent Document 1, since the glass protective film is provided so as to overlap the outer peripheral portion of the electrode pad, it is difficult to increase the area of the electrode pad. Therefore, the object of increasing the electrode area as much as possible cannot be achieved.

JP 2007-250564 A

  The present invention solves the above-described problem, and there is no short-circuit failure at the time of solder bonding with a circuit board for mounting, and the element substrate with improved strength of solder bonding with the mounting board, and such An object of the present invention is to provide a light-emitting device with excellent light extraction efficiency and high reliability using an element substrate.

  The element substrate of the present invention is made of an inorganic insulating material, and a part of the substrate body having a mounting surface serving as a mounting portion on which the light emitting element is mounted, and the electrode of the light emitting element are electrically connected to an external circuit. A conductor formed on the surface and inside of the substrate body, a part of which is provided with a wiring conductor arranged as a plurality of external connection terminals on a non-mounting surface that is a surface opposite to the mounting surface, An element substrate in which a connection terminal is solder-bonded on a wiring circuit of a circuit board, and a non-mounting surface of the substrate body has an inorganic insulation mainly composed of glass in a region between two opposing external connection terminals. A solder adhesion preventing layer made of a material and having a surface roughness Ra of 0.03 μm or less is formed.

In the element substrate of the present invention, the external connection terminals can be arranged at a distance of 100 to 150 μm. Moreover, it is preferable that the said board | substrate body consists of a sintered compact of the 1st glass ceramic composition containing 1st glass powder and 1st ceramic powder. Furthermore, the solder adhesion preventing layer is made of a sintered body of a second glass ceramic composition containing a second glass powder having a glass transition point of 550 to 630 ° C. and a second ceramic powder. Then, the average particle diameter _{D 50} of the second ceramic powder is 1~3μm is preferred. In addition, the content of the second ceramic powder is preferably 3 to 10% by mass with respect to the entire second glass ceramic composition.

  Furthermore, the present invention provides the element substrate of the present invention, a light emitting element mounted on the mounting portion of the element substrate, a circuit board having a wiring circuit on which the element substrate is mounted, and the element substrate as the circuit. There is provided a light emitting device having a solder layer fixed to a substrate, the solder layer connecting the external connection terminal of the element substrate and the wiring circuit.

  Note that in this specification, the “wiring conductor” included in the element substrate is an electric circuit provided so as to be electrically connected to the wiring circuit of the circuit board through the electrode included in the light emitting element to be mounted. All conductors related to wiring, for example, element connection terminals connected to electrodes of light emitting elements, inner layer wiring (including through conductors penetrating the board) provided inside the board, and external connected to the wiring circuit of the circuit board It is used as a generic term for connection terminals and the like.

  Further, “the external connection terminals are disposed at a distance of a μm” means that a distance (interval) between the opposing edges of the external connection terminals is disposed at a μm. That is, the reference of the interval between the external connection terminals is not the center line in the width direction of the external connection terminals but the edge, and each external connection terminal has its own edge and the opposite edge of the adjacent external connection terminal. It is shown that the interval is arranged at a μm.

  In the element substrate of the present invention, the region between the plurality of external connection terminals formed on the non-mounting surface of the substrate body is made of an inorganic insulating material mainly composed of glass and has a surface roughness Ra of 0.03 μm or less. Since the solder adhesion prevention layer is formed, when soldering the external connection terminal of this element substrate to the wiring circuit of the circuit board, the flowed solder does not flow into and adhere to the external connection terminal, and the external connection terminal The short circuit between is prevented. Therefore, the interval between the external connection terminals can be made narrower than the conventional range of 100 to 150 μm, and the electrode area of the external connection terminals can be sufficiently secured. Therefore, a highly reliable light emitting device can be obtained.

1A shows a first embodiment of an element substrate of the present invention, FIG. 1A is a plan view seen from the mounting surface side, FIG. 1B is a plan view seen from the non-mounting surface side, and FIG. FIG. 2 is a sectional view taken along line XX in FIG. FIG. 2A shows a second embodiment of the element substrate of the present invention, FIG. 2A is a plan view seen from the mounting surface side, and FIG. 2B is a plan view seen from the non-mounting surface side. It is sectional drawing of one Embodiment of the light-emitting device of this invention.

  Embodiments of the present invention will be described below 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 is a substrate body made of an inorganic insulating material, part of which has a mounting surface serving as a light emitting element mounting portion, and a conductor formed on the surface and inside of the substrate body. A wiring conductor disposed as a plurality of external connection terminals on a non-mounting surface, and the external connection terminals are soldered onto the wiring circuit of the circuit board. The Then, on the non-mounting surface of the substrate body, in a region between the external connection terminal and the external connection terminal facing the external connection terminal (hereinafter, sometimes referred to as “region between the opposed external connection terminals”). A solder adhesion preventing layer having a surface roughness Ra of 0.03 μm or less made of an inorganic insulating material mainly composed of glass is formed. The surface roughness Ra is represented by 3 “Definition and display of defined arithmetic average roughness” of JIS: B0601 (1994), according to Surfcom 1400D (model name, manufactured by Tokyo Seimitsu Co., Ltd.). It is a measured value.

  In the element substrate of the present invention, a solder adhesion preventing layer having a surface roughness Ra of 0.03 μm or less made of an inorganic insulating material mainly composed of glass is provided in a region between the opposing external connection terminals of the non-mounting surface of the substrate body. As a result, when soldering the external connection terminal to the wiring circuit of the circuit board, the flowed solder is repelled on the smooth surface of the solder adhesion preventing layer and adheres to the surface of the solder adhesion preventing layer. Absent. Therefore, even if the interval between the external connection terminals is narrower than before (for example, 100 to 150 μm), there is no short circuit between the external connection terminals, and a sufficient electrode area of the external connection terminals can be secured to improve the solder joint strength. In addition, since the substrate body is made of an inorganic insulating material such as ceramics or LTCC, the element substrate is excellent in weather resistance, light extraction efficiency, heat dissipation, and the like. Therefore, by mounting such an element substrate on a circuit board by solder bonding, a light emitting device with high reliability of solder bonding and high luminance can be obtained.

  When the surface roughness Ra of the solder adhesion preventing layer formed between the external connection terminals exceeds 0.03 μm, the surface smoothness of the solder adhesion preventing layer is not sufficient, so that the solder adhesion preventing layer flows to the surface of the solder adhesion preventing layer. Solder easily adheres, and the attached solder becomes a bridge, and a short circuit is likely to occur between the external connection terminals. For this reason, when the interval between the external connection terminals is set to 200 μm or less, a short circuit failure occurs, and the light emitting device with high reliability cannot be obtained.

  FIG. 1 shows one embodiment (first embodiment) of an element substrate 1 of the present invention. FIG. 1 (a) is a plan view seen from the upper surface (mounting surface) side, and FIG. FIG. 1C is a cross-sectional view taken along line XX in FIG.

  The element substrate 1 includes a substrate body 2 having a square planar shape and a substantially flat plate shape. In the present specification, “substantially flat plate” means a flat plate at the visual level. Hereinafter, “substantially” indicates a visual level.

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

  In the present 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. Moreover, the raw material composition of the sintered body (LTCC) of the glass ceramic composition constituting the substrate body 2, the sintering conditions, and the like will be described in the method for manufacturing the element substrate 1 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.

  The element substrate 1 has a frame 3 on the peripheral edge of one surface (upper surface) of the substrate body 2. The frame 3 forms a substantially circular cavity with a planar shape, and the bottom surface of the cavity is a mounting surface 21 on which the light emitting element is mounted. In addition, the light emitting element mounting portion 22 is positioned substantially at the center of the cavity bottom surface. The material constituting the frame 3 is not particularly limited, but the same material as that constituting the substrate body 2 is preferable.

  On the element substrate 1, a pair of element connection terminals 4 electrically connected to a pair of electrodes of the light emitting element to be mounted on the mounting surface 21 of the substrate body 2, with the light emitting element mounting portion 22 interposed therebetween. It is arranged to face both sides. One end of each element connection terminal 4 extends in the peripheral direction of the mounting surface 21, and the frame body 3 is arranged and formed so as to cover it. The planar shape and arrangement position of the element connection terminal 4 are not limited to those illustrated.

  A non-mounting surface 23 opposite to the mounting surface 21 of the substrate body 2 is provided with a pair of external connection terminals 5 that are electrically connected by soldering to an external circuit when a light emitting device is formed. For the following reasons, the sizes (electrode areas) of the pair of external connection terminals 5 are greatly different and are arranged asymmetrically with respect to the center line of the non-mounting surface 23. That is, as will be described later, in order to reduce the thermal resistance of the substrate main body 2, the thermal via 8 penetrates the substrate main body 2 directly below the light emitting element mounting portion 22 located at a substantially central portion of the mounting surface 21. A pair of external connection terminals 5 are formed so that the other end portion of the thermal via 8 is in contact with one of the external connection terminals 5 on the non-mounting surface 23 side. Therefore, one of the external connection terminals 5 has a large area so as to cover the end portion of the thermal via 8 exposed at the substantially central portion of the non-mounting surface 23, and the other external connection terminal 5 has a small area. The pair of external connection terminals 5 are disposed with a distance D of 100 to 150 μm.

  In addition, in the region between the pair of external connection terminals 5 on the non-mounting surface 23 of the substrate body 2, solder adhesion made of an inorganic insulating material mainly composed of glass and having a surface roughness Ra of 0.03 μm or less. A prevention layer 6 is formed.

  For the following reasons, it is preferable that the solder adhesion preventing layer 6 is formed so as to have a gap (gap) d between the edges of the pair of external connection terminals 5 whose edges on both sides face each other. . That is, from the viewpoint of the flatness of the solder joint surface (surface) of the external connection terminal 5, it is necessary to avoid the solder adhesion prevention layer 6 from overlapping the external connection terminal 5. Further, when the solder adhesion preventing layer 6 is formed by printing glass paste or the like, there is a risk of displacement, so that the solder adhesion preventing layer 6 runs on the external connection terminal 5 even when the displacement occurs. It is preferable to provide a gap (gap) d between the solder adhesion preventing layer 6 and the external connection terminal 5 so as not to cause a problem. The size of the gap d is, for example, about 20 μm when the distance D between the external connection terminals 5 is 100 μm. By providing such a gap, the solder adhesion preventing layer 6 is efficiently formed by printing glass paste or the like.

  Further, the thickness of the solder adhesion preventing layer 6 is preferably the same as that of the external connection terminal 5. Since the thickness of the external connection terminal 5 is preferably 5 to 15 μm as described later, the solder adhesion preventing layer 6 is also preferably set to the same thickness as the external connection terminal 5 in the range of 5 to 15 μm.

An inorganic insulating material constituting such a solder adhesion preventing layer 6 will be described below. The inorganic insulating material constituting the solder adhesion preventing layer 6 contains at least SiO ₂ , B ₂ O ₃ , and glass containing at least one selected from Na ₂ O and K ₂ O as a main component.

  The inorganic insulating material preferably contains ceramic powder in a proportion of 10% by mass or less. The ceramic powder preferably contains at least one selected from silica powder, alumina powder, zirconia powder, and titania powder. The content of the ceramic powder is more preferably 3% by mass or more. If the ceramic powder exceeds 10% by mass, the fluidity of the inorganic insulating material deteriorates, and not only the solder adhesion preventing layer 6 having a surface roughness of 0.03 μm or less cannot be obtained, but also the flatness is improved. Not enough.

Furthermore, the average particle diameter D ₅₀ (hereinafter sometimes simply referred to as D ₅₀ ) of the ceramic powder is preferably 1 to 3 μm. If the D ₅₀ of the ceramic powder was the range, enhance the printability of the inorganic insulating material, and by flattening the solder adhesion preventing layer 6 ends, can be suppressed undulation of the layer surface. Note that D ₅₀ is a value measured by a particle size measuring apparatus using a laser diffraction / scattering method.

  Next, glass which is a main component of the inorganic insulating material constituting the solder adhesion preventing layer 6 will be described.

As the glass, as represented by mol% based on oxides, the _{SiO 2 58~84%, B 2 O} 3 10 to 25%, the _Al 2 _{O 3 0~6%,} the Na ₂ O and _{K 2} O The total content of at least one selected from 1 to 5%, the total content of SiO ₂ and Al ₂ O ₃ is 65 to 84%, MgO is 0 to 10%, at least one of CaO and SrO What baked the powder of the borosilicate glass containing 0 to 15% in total is preferable.

  The glass transition point (Tg) of the borosilicate glass is preferably 550 to 630 ° C. When glass having a glass transition point (Tg) of less than 550 ° C. is used, degreasing becomes difficult or the glass flows too much to keep the area of the solder adhesion preventing layer 6 on the wiring conductor. Glass may flow and adhere, and solderability may be reduced. In addition, when a glass having a glass transition point (Tg) exceeding 630 ° C. is used, not only does the shrinkage start temperature increase and the dimensional accuracy of the solder adhesion preventing layer 6 may decrease, but also during firing. The fluidity of the inorganic insulating material is not sufficient, and the solder adhesion preventing layer 6 having a surface roughness Ra of 0.03 μm or less cannot be formed. Further, the softening point (Ts) of the borosilicate glass is preferably 900 ° C. or less. When the glass softening point (Ts) exceeds 900 ° C., a firing temperature exceeding 900 ° C. is required to obtain a dense sintered body by firing this glass powder. For example, a silver paste is used. The formed wiring conductor may be deformed. As the glass powder for forming the solder adhesion preventing layer 6, the softening point (Ts) is 900 ° C. or less, and there is no deformation of the wiring conductor mainly composed of silver, and these can be fired simultaneously.

  Next, each component of the borosilicate glass having the above composition will be described. In the following description, unless otherwise specified, the composition is expressed in mol% on the basis of oxide, and is simply expressed as%.

SiO ₂ is a glass network former, a component that increases chemical durability, particularly acid resistance, and is essential. If it is less than 58%, the acid resistance may be insufficient. If it exceeds 84%, the glass softening point (Ts) tends to be high, or the glass transition point (Tg) tends to be too high.

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

Al ₂ O ₃ is not essential, but may be contained in a range of 6% or less in order to enhance the stability or chemical durability of the glass. If it exceeds 6%, the transparency of the glass may decrease.

The total content of SiO ₂ and Al ₂ O ₃ is 65 to 84%. If it is less than 65%, chemical durability may be insufficient. If it exceeds 84%, the glass melting temperature becomes high, or the glass transition point (Tg) becomes too high.

Na ₂ O and K ₂ O are components that lower the glass transition point (Tg), and at least one of them is essential. It can contain up to 5% in total. If it exceeds 5%, chemical durability, particularly acid resistance, may deteriorate. Moreover, there exists a possibility that the electrical insulation of a sintered compact may fall. Na ₂ O, containing any one or more of _{K 2 O,} Na 2 O, the total content of _{K 2} O is at least 1% is preferred.

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

  Neither CaO nor SrO is essential, but in order to lower the glass softening point (Ts) or stabilize the glass, a total of up to 15% may be contained. If it exceeds 15%, the acid resistance may decrease.

  The glass that is the main component of the solder adhesion preventing layer 6 consists essentially of the above components, but may contain other components within a range that does not impair the object of the present invention. When other components are contained, the total content of these components is preferably 10% or less. However, lead oxide is not contained.

  The solder adhesion preventing layer 6 of the present invention is formed by firing a glass ceramic composition obtained by mixing such a borosilicate glass powder composed of each component and, if necessary, the ceramic powder. The mixed powder of the borosilicate glass powder having the above composition and the ceramic powder is formed into a paste, screen-printed, and fired. However, in the region between the pair of external connection terminals 5 formed on the non-mounting surface 23 of the substrate body 2, the same surface roughness Ra as the external connection terminals 5 is 5 to 15 μm and 0.03 μm or less. The forming method is not particularly limited as long as the solder adhesion preventing layer 6 can be formed.

  Furthermore, in the element substrate 1 of the present invention, a pair of connection vias 7 that electrically connect the pair of element connection terminals 4 and the pair of external connection terminals 5 to each other inside the substrate body 2 are provided on the substrate body. 2 is penetrated in the thickness direction. The arrangement positions and shapes of the element connection terminal 4, the external connection terminal 5 and the connection via 7 are the same as those shown in FIG. 1 as long as they are electrically connected to the element connection terminal 4 → the connection via 7 → the external connection terminal 5. It is not limited and can be adjusted appropriately.

  In addition, the constituent materials of the element connection terminals 4, the external connection terminals 5, and the connection vias 7 that are wiring conductors can be used without particular limitation as long as they are the same constituent materials as the wiring conductors used for the element substrate. Specifically, the constituent material of these wiring conductors is a metal material mainly containing at least one 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 preferable.

  The film thickness of the element connection terminal 4 and the external connection terminal 5 is such that the particle size of the metal particles, which are the constituent particles of the metal paste usually used for forming them, is several μm, and a sufficient amount of metal is obtained by sintering the paste. From the viewpoint of the presence of particles, 5 to 15 μm is preferable, and a range of 7 to 12 μm is more preferable. In the external connection terminal 5, a conductive protective layer (not shown) that protects this layer from oxidation and sulfurization and has conductivity on the metal conductor layer made of the metal material 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 metal conductor layer. However, the material is not limited to nickel plating layer, nickel / gold plating layer, silver plating layer, nickel / silver plating. A layer, a chromium plating layer and the like are preferable, and a nickel / gold plating layer is particularly preferable.

  Further, from the viewpoint of obtaining good bonding with a bonding wire to be described later, a conductive protective layer such as a gold plating layer or a nickel / gold plating layer obtained by performing gold plating on the nickel plating (see FIG. (Not shown) is preferred.

  Furthermore, the element substrate 1 has a thermal via 8 embedded in the substrate body 2 for reducing thermal resistance. For example, as shown in FIG. 1, the thermal via 8 has a columnar shape having substantially the same cross-sectional area as the area of the light emitting element mounting portion 22, and the substrate body 2 is disposed at a position immediately below the light emitting element mounting portion 22 in the thickness direction. Has penetrated. That is, the thermal via 8 is exposed with its upper end reaching the mounting surface 21. The other end (lower end) of the thermal via 8 reaches the non-mounting surface 22 and is in contact with the external connection terminal 5 having a large area. The thermal via 8 having such a configuration can efficiently dissipate heat from the light emitting element to the outside via the thermal via 8 and the external connection terminal 5.

  In the element substrate 1 of the present invention, the position, shape, size, number, etc., of the thermal vias 8 are not limited to those shown in FIG. A layer for heat radiation to the outside can be provided on the non-mounting surface 23 of the substrate body 2 so as to be connected to the thermal via 8 separately from the external connection terminals 5.

  The material constituting the thermal via 8 is not particularly limited as long as it is a material having heat dissipation properties. However, a metal material containing silver, specifically, a metal material made of silver, silver and platinum, or silver and palladium is used. preferable.

  The first embodiment of the element substrate 1 of the present invention has been described above, but the structure of the element substrate 1 of the present invention is not limited to this.

  2A and 2B show a second embodiment of the element substrate 1 of the present invention. FIG. 2A is a plan view seen from the mounting surface side, and FIG. 2B is a plan view seen from the non-mounting surface side. .

The element substrate 1 has a substantially flat plate-like substrate body 2 having a rectangular planar shape. A frame body 3 is disposed on the peripheral edge of the upper surface of the substrate body 2, and a substantially rectangular cavity is formed by the frame body 3. Is formed. On the light emitting element mounting surface 21 that is the bottom surface of the cavity, a pair of element connection terminals 4 are provided with a light emitting element mounting portion 22 positioned substantially at the center. Further, on the mounting surface 21 of the substrate body 2, a silver reflection film 9 is formed except for predetermined regions on the element connection terminals 4 and the outer periphery of the element connection terminals 4.
Further, on the non-mounting surface 23 of the substrate body 2, a pair of external connection terminals 5 connected to the pair of element connection terminals 4 via connection vias 7 are disposed. In this region, a solder adhesion preventing layer 6 made of an inorganic insulating material mainly composed of glass and having a surface roughness Ra of 0.03 μm or less is formed. Furthermore, the thermal via 8 penetrates the substrate body 2 in the thickness direction at a position immediately below the light emitting element mounting portion 22. In this element substrate 1, the constituent materials such as the substrate body 2, the element connection terminals 4, the external connection terminals 5, the solder adhesion preventing layer 6, and the thermal via 8 are the same as those in the first embodiment shown in FIG. 1. Therefore, explanation is omitted.

  In the element substrate 1 configured as described above, since the surface-smooth solder adhesion preventing layer 6 having a surface roughness Ra of 0.03 μm or less is formed between the external connection terminals 5, the external connection terminals 5 are soldered together. In this case, the flowed solder does not adhere between the external connection terminals 5. Therefore, even if the interval between the external connection terminals is narrower than the conventional one and is 100 to 150 μm, there is no short circuit between the external connection terminals 5 and the element substrate 1 with high reliability is obtained.

  Next, a preferred embodiment of a light emitting device 10 using the element substrate 1 of the present invention will be described based on the drawings. Note that the light-emitting device of the present invention is not limited to this. FIG. 3 is a cross-sectional view showing an example of a light emitting device 10 using the element substrate 1 shown in FIG.

  A light-emitting device 10 of the present invention includes the above-described element substrate 1 of the present invention and a light-emitting element (for example, LED element) 11 mounted on the element substrate 1. The light emitting element 11 is fixed to the light emitting element mounting portion 22 of the mounting surface 21 of the substrate body 2 with a die bond material 12 such as a silicone die bond material. The thermal via 8 provided through the substrate body 2 is exposed at the position of the light emitting element mounting portion 22 on the mounting surface 21, but the light emitting element 11 has a silicon die bond material, silver or the like on it. It is bonded via a conductive die bond material containing a conductor or a die bond material 12 made of gold / tin eutectic solder. A pair of electrodes (not shown) included in the light-emitting element 11 are electrically connected to the pair of element connection terminals 4 located outside thereof via bonding wires 13. A resin sealing layer 14 is provided so as to cover the light emitting element 11 and the bonding wire 13 and fill the cavity.

  In the light emitting device 10 of the present invention, the element substrate 1 on which the light emitting element 11 is mounted in this way has a configuration in which it is mounted on a circuit board 15 such as a printed wiring board. The circuit board 15 has a wiring circuit 16 at least on the side facing the external connection terminal 5 of the element substrate 1, and the wiring circuit 16 and the external connection terminal 5 of the element substrate 1 are solder layers. It is mounted by being bonded and fixed via 17 and electrically connected. Here, as the circuit board 15, for example, a printed wiring board having a wiring circuit 16 made of a copper foil on at least one main surface using a thermosetting resin such as an epoxy resin as an insulating base material is used.

  Thus, the element substrate 1 on which the light emitting element 11 is mounted and the circuit board 15 are configured such that the electrode of the light emitting element 11 → the bonding wire 13 → the element connection terminal 4 → the connection via 7 → the external connection terminal 5 → the solder layer 17 → the wiring. The circuit 16 is electrically connected by a conduction path. On the other hand, as a heat path, a path from the light emitting element 11 through the thermal via 8 to the external connection terminal 5 is formed, from which heat is further dissipated through the solder layer 17 and the wiring circuit 16.

  As the solder constituting the solder layer 17, a solder material used for fixing a substrate made of LTCC material to a circuit board is usually used. A solder material used in a reflow method is preferred. Specific examples include solder materials made of (tin + silver), (tin + copper), (tin + silver + copper), and the like. The thickness of the solder layer 17 is preferably 10 to 50 μm, and more preferably 20 to 40 μm, from the viewpoint of bonding strength and ease of formation while ensuring sufficient solder bonding.

  For the manufacture of the element substrate 1 and the light emitting device 10 of the present invention configured as described above, materials and methods usually used for manufacturing a light emitting element LTCC substrate and a light emitting device using the same can be applied. For example, the element substrate 1 shown in FIG. 1 and the light emitting device 10 shown in FIG. 3 can be manufactured by a manufacturing method including the following steps. In the following description, members used for manufacturing will be described with the same reference numerals as those of the finished product.

(1) Production of Green Sheet As a green sheet for forming the substrate body 2 of the element substrate, a glass ceramic composition containing glass powder and ceramic powder is used, and a plurality of flat plates (for example, for upper layer and lower layer) 2) green sheet 2 for main body. Also, a frame green sheet 3 for forming the frame 3 is prepared. The frame green sheet 3 is produced by hollowing out each of the cavities from a plurality of green sheets of the same size as the main body green sheet 2.

  The green sheet 2 for the main body and the green sheet 3 for the frame body are prepared by adding a binder and, if necessary, a plasticizer, a dispersant, a solvent, etc. to a glass ceramic composition containing glass powder and ceramic powder. This is formed into a sheet having a predetermined shape by a doctor blade method or the like and dried.

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

  Further, the glass powder for main body is preferably one in which crystals are precipitated when fired at 800 ° C. or higher and 930 ° C. or lower. In the case where crystals do not precipitate, there is a possibility that sufficient mechanical strength cannot be obtained. Furthermore, the crystallization peak temperature (Tc) measured by DTA (differential thermal analysis) is preferably 880 ° C. or less. When Tc exceeds 880 ° C., the dimensional accuracy may be reduced.

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

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

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

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

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

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

  In addition, the glass powder for main bodies is not necessarily limited to what consists only of the said component, Other components can be contained in the range with which various characteristics, such as a glass transition point (Tg), are satisfy | filled. When other components are contained, the total content is preferably 10% or less.

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

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

  As the ceramic powder for the main body for producing the green sheet for the main body, those conventionally used for manufacturing LTCC substrates can be used. For example, alumina powder, zirconia powder and the like can be preferably used. A mixture of alumina powder and ceramic powder having a higher refractive index than alumina can also be used.

Ceramic powder having a refractive index higher than that of alumina is a component for improving the reflectance of a sintered substrate, and examples thereof include titania powder, zirconia powder, and stabilized zirconia powder. While the refractive index of alumina is about 1.8, the refractive index of titania is about 2.7 and the refractive index of zirconia is about 2.2, which is higher than that of alumina. . The D ₅₀ of these ceramic powders is preferably 0.5 μm or more and 4 μm or less.

  The main body glass powder and the main body ceramic powder are blended in, for example, 30% by mass to 50% by mass of the main body glass powder, and 50% by mass to 70% by mass of the main body ceramic powder. A glass ceramic composition for use 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 for main body.

  As the binder resin, 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, di-2-ethylhexyl 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.

(2) Formation of wiring conductor paste layer and metal paste layer for heat dissipation When these are laminated at a predetermined position on the substantially central portion of each main body green sheet 2 obtained in the above process and on both sides. A through-hole for forming a thermal via and a through-hole for forming a connection via formed so as to penetrate from the mounting surface 21 of the substrate body 2 to the non-mounting surface 23 with a predetermined cross-sectional shape and size by a normal method Form.

Next, the conductive via paste layer 7 for connection via is formed in two through-holes for forming connection vias in the upper and lower two main body green sheets 2, and the mounting surface of the upper main body green sheet 2 is mounted. A pair of element connection terminal conductor paste layers 4 are formed in a predetermined size and shape so as to be connected to the connection via conductor paste layer 7 on one surface to be 21.
In addition, a pair of external connection terminal conductor paste layers 5 are connected to the connection via conductor paste layer 7 on one surface which is the non-mounting surface 23 of the lower body green sheet 2. And form in shape. The element connection terminal conductor paste layer 4, the connection via conductor paste layer 7, and the external connection terminal conductor paste layer 5 are collectively referred to as a wiring conductor paste layer.

  As the wiring conductor paste constituting these wiring conductor paste layers, for example, a conductive metal powder containing at least one of copper, silver, gold and the like as a main component, a vehicle such as ethyl cellulose, and a solvent as necessary are added. The paste is used. The conductive metal powder is preferably a metal powder made of silver or a metal powder made of silver and platinum or palladium.

  In order to form the wiring conductor paste layer, for example, the conductor paste is applied and filled by screen printing. The thickness of the formed wiring conductor paste layer is adjusted so that the film thicknesses of the finally obtained element connection terminals 4 and external connection terminals 5 become predetermined film thicknesses.

  Further, the thermal via paste layer 8 is formed in the through holes for forming the thermal vias of the upper and lower main body green sheets 2. In order to form the thermal via paste layer 8, the heat dissipating metal paste can be prepared in the same manner as the wiring conductor paste using metal powder as a heat dissipating material. Examples of the metal powder that is a heat dissipating material include silver, a silver palladium mixture, and a silver platinum mixture. Thus, when using silver, a silver palladium mixture, a silver platinum mixture, etc. preferable for the wiring conductor paste as the heat-dissipating metal powder, one type of paste is used for the element connection terminal conductor paste layer 4 and the external connection terminal. The conductive paste layer 5 for connection, the conductive paste layer 7 for connection vias, and the thermal via paste layer 8 can all be formed. In order to form the thermal via paste layer 8, for example, a heat dissipating metal paste is applied and filled by screen printing.

(3) Formation of glass paste layer for preventing solder adhesion In the lower body green sheet 2 for the main body, solder adhesion is prevented in the region between the pair of conductor paste layers 5 for external connection terminals formed in the step (2). A glass paste layer 6 is formed.

  The glass paste for preventing solder adhesion is composed of a glass ceramic composition obtained by mixing the glass powder for the solder adhesion preventing layer 6 and ceramic powder as required, a vehicle such as ethyl cellulose, and a solvent as required. A paste-like material is added. The thickness of the formed solder adhesion preventing glass paste layer 6 is adjusted so that the finally obtained solder adhesion preventing layer 6 has the same thickness as the external connection terminal 5. The surface roughness Ra of the finally obtained solder adhesion preventing layer 6 depends on the composition, glass transition point (Tg) of each component in the glass powder for the solder adhesion preventing layer 6 and the particle size and content of the ceramic powder. It is adjusted to 0.3 μm or less. That is, as the glass powder for the solder adhesion preventing layer 6, a composition and particle size excellent in fluidity that are sufficiently melted during firing are used, and the composition of the mixture with the ceramic powder is superior in fluidity during firing. The solder adhesion preventing layer 5 having a surface roughness Ra of 0.3 μm or less can be formed.

  In order to form the solder paste preventing glass paste layer, for example, it is applied by screen printing.

(4) Lamination of Green Sheets of the green sheet 2 for the lower body with the wiring conductor paste layer, the heat dissipating metal paste layer and the glass paste layer for preventing solder adhesion obtained in the steps (2) and (3). The upper body green sheet 2 with the wiring conductor paste layer and the heat dissipating metal paste layer was laminated thereon, and further obtained on the mounting surface 21 of the upper body green sheet 2 in the step (1). The green sheet 3 for frames is laminated. Thus, a green sheet laminate having a cavity on the mounting surface 21 and a bottom surface of the cavity having the light emitting element mounting portion 22 is obtained as the unfired element substrate 1.

(5) Firing The green ceramic substrate 1 obtained in the step (4) is subjected to degreasing to remove a binder or the like, if necessary, and then a glass ceramic composition or the like is sintered. Firing is performed.

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

  In addition, the firing can be performed by appropriately adjusting the time in a temperature range of 800 ° C. to 930 ° C. in consideration of obtaining a dense structure of the substrate body 2 and the frame body 3 and productivity. Specifically, it is preferable to hold 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. If the firing temperature is less than 800 ° C., the substrate body 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 substrate body 2. In addition, when a metal paste containing a metal powder containing silver as a main component is used as the wiring conductor paste or the heat dissipating metal paste, when the firing temperature exceeds 880 ° C., a predetermined shape is required to soften excessively. May not be able to maintain.

  In this way, the unsintered element substrate 1 is fired to obtain the element substrate 1. After firing, the element connection terminal 4 and the external connection terminal 5 are covered with a gold plating layer, and the external connection terminal 5 is a nickel plating layer so that the surfaces of the element connection terminal 4 and the external connection terminal 5 are covered. The conductive protective layer used in the above can be formed.

  Although the manufacturing method of the element substrate 1 has been described above, the frame green sheet 3 does not have to be a single green sheet, and may be a laminate of a plurality of green sheets. Further, the order of forming each part can be changed as appropriate as long as the element substrate can be manufactured.

  Furthermore, as described above, the inorganic insulating material constituting the base body 2 and the frame 3 may be an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, etc. In the case of using the ceramic sintered body, the substrate main body 2 and the like can be manufactured similarly to the LTCC. That is, a slurry is prepared by adding a binder and, if necessary, a plasticizer, a dispersant, a solvent, etc. to the raw material composition of the ceramic sintered body, and this is formed into a sheet of a predetermined shape by a doctor blade method or the like. And dried, degreased as necessary, and a firing temperature suitable for the ceramic sintered body to be used, for example, 1400 to 1700 ° C. in an aluminum oxide sintered body and 1700 in an aluminum nitride sintered body. Firing is performed at a temperature of 1950 ° C. to obtain a sintered body.

In addition, as a raw material of the ceramic sintered body containing the aluminum as a main component, for example, a compound such as aluminum oxide, aluminum hydroxide, aluminum halide, aluminum sulfate, aluminum nitrate, aluminum sulfide, aluminum nitride, anorthite ( NaAlSi ₃ O ₈ ), alum (KAl ₃ (OH) ₆ (SO ₄ ) ₂ ), boehmite (AlO (OH)), corundum (Al ₂ O ₃ ), kaolinite (Al ₂ Si ₂ O ₅ (OH) ₄ ), Mullite (Al ₆ Si ₂ O ₁₃ ), sericite (KAl ₂ (AlSi ₃ O ₁₀ ) (OH) ₂ ) and other minerals containing the above compounds, or synthetic materials using the above compounds as raw materials. .

  The binder and optional plasticizer, dispersant, solvent, and the like for preparing the slurry can be configured in the same manner as the LTCC. In addition, also in the manufacturing process of a ceramic sintered compact, it can carry out similarly to LTCC except the said baking conditions.

(6) Production of Light-Emitting Device The method for producing the light-emitting device 10 shown in FIG. 3 using the element substrate 1 is not particularly limited, for example, a method for mounting the light-emitting element 11 on the element substrate 1, wire bonding, or the like. Conventionally known methods can be applied to the electrical connection method, the method of forming the resin sealing layer 14 using a sealant, and the method of bonding the element substrate 1 to the circuit board 15 by soldering.

  The embodiment of the element substrate 1 and the light emitting device 10 using the element substrate 1 according to the present invention has been described with reference to the examples shown in FIGS. 1 and 3. However, the element substrate and the light emitting device according to the present invention are not limited thereto. It is not something. As long as it does not contradict the spirit of the present invention, the configuration can be changed as necessary.

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

Examples 1-4, Comparative Examples 1-11
The element substrate 1 shown in FIG. 1 was manufactured by the following method. First, main body green sheets (upper main body green sheet and lower main body green sheet) for manufacturing the substrate main body 2 of the element substrate 1 were prepared. In the production of the green sheet for the main body, in terms of mol% based on oxide, SiO ₂ is 60.4%, B ₂ O ₃ is 15.6%, Al ₂ O ₃ is 6%, CaO is 15%, K _{2 O} 1%, blending the Na 2 _O 2% of the raw materials, mixing, after the raw material mixture was melted for 60 minutes at placed in 1600 ° C. in a platinum crucible and glass was cast and cooled in a molten state. This glass was pulverized with an alumina ball mill for 40 hours to produce a glass powder for a main body. In addition, ethyl alcohol was used as a solvent for pulverization.

  Next, 38% by mass of this glass powder, 38% by mass of alumina powder (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 at 24% by mass and mixed to produce a glass ceramic composition for the main body. 50 g of this glass ceramic composition, 15 g of an organic solvent (toluene, xylene, 2-propanol, 2-butanol mixed at a mass ratio of 4: 2: 2: 1), plasticizer (di-2-ethylhexyl phthalate) 2.5 g of polyvinyl butyral (trade name: PVK # 3000K, manufactured by Denka) 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 sheets were laminated so that the thickness after firing was 0.5 mm to produce upper and lower body green sheets. Further, green sheets manufactured in the same manner as these green sheets for main bodies were processed into a predetermined shape to produce green sheets for frames.

  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 in a mass ratio of 85:15, and the solid content is 85 mass% after being dispersed in α-terpineol as a solvent. Then, the mixture was kneaded for 1 hour in a porcelain mortar, and further dispersed three times with three rolls to produce a conductor paste.

  The conductor paste is screen-printed on the upper surface of the upper green sheet for the main body to form a conductor paste layer for element connection terminals, and a hole having a diameter of 0.15 mm is formed in the portion corresponding to the connection via. A hole was formed, and the conductive paste was filled by the screen printing method to form a conductive paste layer for connection via. Further, a through hole having a diameter of 1 mm was formed in a portion corresponding to the thermal via using a hole punch, and the conductive paste was filled by a screen printing method to form a thermal via conductive paste layer.

  Further, the conductor paste is screen-printed on the lower surface of the lower body green sheet to form a conductor paste layer for external connection terminals, and the diameter corresponding to the thermal via and the connection via is formed using a hole punch. A through hole having a diameter of 1 mm and a diameter of 0.15 mm was formed, and the conductive paste was filled by screen printing to form a thermal via conductor paste layer and a connection via conductor paste layer. In addition, the space | interval of a pair of conductor paste layer for external connection terminals was 100 micrometers.

Next, three types of glass powders A to C for preventing solder adhesion were produced, and using these glass powders A to C, the glass for preventing solder adhesion used in Examples 1 to 4 and Comparative Examples 1 to 11 were used. Each paste was prepared. That is, first, raw materials are prepared and mixed in the composition shown in Table 1 in terms of mol% on the basis of oxide, and the raw material mixture is put in a platinum crucible and heated and melted at 1600 ° C. for 60 minutes, and then the molten glass is prepared. The glass thus obtained was poured and cooled, and then the obtained glass was pulverized with an alumina ball mill using ethanol as a solvent for 40 hours. Thus, glass powders A to C for preventing solder adhesion were produced, respectively. The 50% particle size (D ₅₀ ) of the obtained glass powders A to C was measured using a laser diffraction particle size distribution analyzer (SALD2100) manufactured by Shimadzu Corporation, and all were 2.0 μm. Moreover, when the glass transition point (Tg) and glass softening point (Ts) of glass powder AC were measured by Shimadzu Corporation DTA-50, the result shown in Table 1 was obtained.

  Next, any one of these three types of glass powders A to C and alumina powder (product name: AL47H, manufactured by Showa Denko KK) were blended and mixed at a ratio (mass%) shown in Table 2 for the content of alumina powder. . And after blending 60% by mass of this mixture and 40% by mass of a resin component (containing ethyl cellulose and α-terpineol in a mass ratio of 85:15), the mixture was kneaded in a zirconia mortar for 3 hours, Furthermore, it disperse | distributed 3 times with the triple roll made from an alumina, and prepared the glass paste for solder adhesion prevention used in Examples 1-4 and Comparative Examples 1-11, respectively.

  Then, the solder paste preventing glass paste prepared as described above is screen-printed with a width of 80 μm in a region of 100 μm width between the pair of conductor paste layers for external connection terminals on the lower surface of the lower body green sheet. Then, a glass paste layer for preventing solder adhesion was formed.

  Next, the lower body green sheet with the solder paste-preventing glass paste layer and the conductor paste layer and the upper body green sheet with the conductor paste layer were overlapped, and the upper body green sheet was further layered. A green sheet for a frame body was stacked on top of each other and then integrated by thermocompression bonding. Thus, an unfired element substrate was obtained.

  The obtained unfired element substrate was degreased by holding at 550 ° C. for 5 hours, and further held and fired at 870 ° C. for 30 minutes to produce an element substrate 1. In the obtained element substrate 1, the surface roughness Ra of the solder adhesion preventing layer 6 after firing was measured with Surfcom 1400D (manufactured by Tokyo Seimitsu Co., Ltd.). The measurement results are shown in Table 2.

  Next, a 2-wire type LED element (manufactured by Epistar, trade name: ES-CEBLV45) is die-bonded to the light emitting element mounting portion 22 of the element substrate 1 manufactured as described above (trade name: KER, manufactured by Shin-Etsu Chemical Co., Ltd.). -3000-M2), and a pair of electrodes of the LED element was electrically connected to the element connection terminal 4 by the bonding wire 13, respectively. Furthermore, the resin sealing layer 14 was formed using the sealing agent (Shin-Etsu Chemical Co., Ltd. make, brand name: SCR-1016A).

  The substrate on which the LED element thus obtained was mounted was bonded onto the circuit board 15 via the solder layer 17. As the circuit board 15, a glass epoxy board (FR4) was used. This circuit board has a wiring circuit 16 including a pair of mounting terminals formed at a distance of 100 μm on the surface of the element substrate 1 facing the external connection terminal 5, and the substrate on which the LED element is mounted. A pair of external connection terminals 5 were arranged on the corresponding mounting terminals and joined by a solder layer 17 having a thickness of 50 μm.

  The planar shape of the solder layer 17 was the same as that of the external connection terminals 5, and the mounting of the element substrate 1 to the circuit board 15 by solder bonding was performed by solder reflow. In this way, 50 light emitting devices 10 were produced in each example and comparative example, the number of the short-circuited external connection terminals 5 was counted, and the short-circuit rate was calculated. The presence or absence of a short circuit in the external connection terminal 5 was measured with a digital multimeter PM-3 (manufactured by Sanwa Denki Keiki Co., Ltd.). The measurement results are shown in Table 2. In addition, the short circuit rate of an external connection terminal must be 0%, and other than that cannot be used as a product.

  Table 2 shows the following. That is, in the light-emitting device 10 using the element substrate 1 of Examples 1 to 4, the pair of external connection terminals 5 are arranged at an extremely narrow interval of 100 μm, but glass is interposed between these external connection terminals 5. Since the solder adhesion preventing layer 6 having a surface roughness Ra as a main component of 0.03 μm or less is formed, the short circuit rate when the external connection terminal 5 is joined to the circuit board 15 via the solder layer 17 is 0. %, And no short circuit occurs between the external connection terminals 5 due to the flowing solder.

  On the other hand, in the light emitting device 10 using the element substrate 1 of Comparative Examples 1 to 11, a layer mainly composed of glass is provided between the external connection terminals 5 arranged at the same intervals as in Examples 1 to 4. Although formed, this layer has a surface roughness Ra exceeding 0.03 μm, so that the effect of preventing solder adhesion is not sufficient, and a short circuit failure between the external connection terminals 5 occurs. I understand.

  According to the present invention, in an element substrate having external connection terminals arranged at a narrow interval of 100 to 150 μm, and mounting these external connection terminals on a wiring circuit of a circuit board by solder bonding, As a result, the solder that has flowed in between flows into the external connection terminals of the element substrate, and there is no short circuit between the external connection terminals, so that a highly reliable light emitting device can be obtained. Such a light-emitting device of the present invention can be suitably used as a backlight for mobile phones, large liquid crystal displays, etc., illumination for automobiles or decoration, and other light sources.

DESCRIPTION OF SYMBOLS 1 ... Element board | substrate, 2 ... Board | substrate body, 3 ... Frame body, 4 ... Element connection terminal, 5 ... External connection terminal, 6 ... Solder adhesion prevention layer, 7 ... Connection via, 8 ... Thermal via, 9 ... Silver reflection film, DESCRIPTION OF SYMBOLS 10 ... Light-emitting device, 11 ... Light emitting element, 12 ... Die bond material, 13 ... Bonding wire, 14 ... Resin sealing layer, 15 ... Circuit board, 16 ... Wiring circuit, 21 ... Mounting surface, 23 ... Non-mounting surface

Claims (7)

A substrate body made of an inorganic insulating material and having a mounting surface part of which is a mounting portion on which a light emitting element is mounted;
Conductors formed on and in the surface of the substrate main body so as to electrically connect the electrodes of the light emitting element to an external circuit, a part of which is a plurality of non-mounting surfaces on the opposite side of the mounting surface A wiring conductor arranged as an external connection terminal of
The external connection terminal is an element substrate to be soldered onto a wiring circuit of a circuit board,
On the non-mounting surface of the substrate main body, a solder adhesion preventing layer made of an inorganic insulating material mainly composed of glass and having a surface roughness Ra of 0.03 μm or less is formed in a region between two opposing external connection terminals. An element substrate.   2. The element substrate according to claim 1, wherein the external connection terminals are arranged at a distance of 100 to 150 μm.   The element substrate according to claim 1, wherein the substrate body is made of a sintered body of a first glass ceramic composition including a first glass powder and a first ceramic powder.   The solder adhesion preventing layer is made of a sintered body of a second glass ceramic composition containing a second glass powder having a glass transition point of 550 to 630 ° C and a second ceramic powder. The element substrate according to any one of the above. The element substrate according to claim 4, wherein the second ceramic powder has an average particle diameter D ₅₀ of 1 to 3 μm.   6. The element substrate according to claim 4, wherein a content of the second ceramic powder is 3 to 10% by mass of the entire second glass ceramic composition. The element substrate according to any one of claims 1 to 6,
A light emitting element mounted on the mounting portion of the element substrate;
A circuit board having a wiring circuit on which the element substrate is mounted;
A solder layer for fixing the element substrate to the circuit board, the solder layer connecting the external connection terminal of the element substrate and the wiring circuit;
A light emitting device comprising:

Images