JP5381799B2 - Light-emitting element mounting substrate and light-emitting device using the substrate - Google Patents

Description

  The present invention relates to a light-emitting element mounting substrate and a light-emitting device using the same, and more particularly to a light-emitting element mounting substrate capable of preventing a decrease in reflectance and a light-emitting device using the same.

  2. Description of the Related Art In recent years, light emitting devices using light emitting elements have been used as lighting, various displays, backlights for large liquid crystal televisions, and the like as light emitting diode elements (light emitting elements) become brighter and whiter. In general, a light emitting element mounting substrate on which a light emitting element is mounted is required to have high reflectivity for efficiently reflecting light emitted from the element.

  For this reason, conventionally, an attempt has been made to apply a reflective layer to the substrate surface for the purpose of reflecting light emitted from the light emitting element as far forward as possible. As such a reflective layer, there is a silver reflective layer having a high reflectance.

However, silver is easily corroded, and if left as it is, a compound such as Ag ₂ S is generated on the surface and the light reflectance is likely to be lowered. As a countermeasure, a method has been proposed in which the surface of silver is coated with a resin such as a silicone resin, an acrylic resin, an epoxy resin, or a urethane resin (see Patent Document 1). However, in this method, moisture or corrosive gas enters the resin or from the interface between the silver conductor layer and the resin, and the silver conductor layer is corroded over time. It was difficult.

  Therefore, in order to prevent corrosion of the silver conductor layer, a method of coating the surface of silver with a glass layer has been proposed (see Patent Document 2).

  On the other hand, a low temperature co-fired ceramic (hereinafter referred to as LTCC) is known as a method for efficiently producing a ceramic substrate by simultaneous firing with a conductor such as silver. The LTCC may be formed into a green sheet, and a plurality of green sheets laminated and sintered may be used as a ceramic substrate. In this case, the internal wiring layer can be formed by applying a metal paste on the green sheet.

JP 2007-67116 A JP 2009-231440 A

  In Patent Document 2, a silver conductor paste is formed on a ceramic (alumina) substrate manufactured by firing to form a silver wiring conductor, and further, a glass paste is applied onto the wiring conductor and fired. Describes a method of coating the surface of silver with a glass layer. However, in the method disclosed in Patent Document 2, it is necessary to repeat the firing step in forming the silver conductor layer and the glass layer.

  Therefore, the present inventor has developed a substrate on which a light emitting element is mounted using LTCC, an internal wiring layer for power feeding, a reflective layer formed of a metal such as silver on the substrate surface, and this reflective layer from corrosion. An attempt was made to form the glass layers to be protected together by firing once.

  However, when the glass paste described in Patent Document 2 was used for LTCC and co-fired, large deformation occurred in the substrate. The glass paste (manufactured by Asahi Glass Co., Ltd., trade name: AP5700) described in Patent Document 2 has a crystallization temperature Tc of about 880 ° C. The layer is easy to crystallize. When the glass layer on the surface is crystallized, the shrinkage behavior of the ceramic substrate portion and the glass layer portion is greatly different in the firing step and the cooling step after firing. Therefore, it is considered that the glass layer on the surface is crystallized in the baking process, and thereby the substrate is deformed.

  An object of the present invention is to provide a light-emitting element mounting substrate that does not deform after firing, prevents the reflective layer from corrosion, and has excellent long-term reliability. It is another object of the present invention to provide a light emitting device using this light emitting element mounting substrate.

The present invention provides a substrate for mounting a light-emitting element, a substrate body having a mounting surface on which the light-emitting element is mounted, a reflective layer containing silver formed on a part of the mounting surface of the substrate body, and on the reflective layer and a vitreous insulating layer formed, the vitreous insulating layer, as represented by mol% based on oxides, the SiO ₂ 30 to 65%, the _{Al 2 O 3 1~ 8%,} B 2 O 3 the 0~40%, MgO + CaO + SrO + BaO 5-50% of ZnO 0 to _15% are formed by softening point 900 ° C. or less of the glass containing 0 to 1% of _{Li 2 O + Na 2 O +} K 2 O. In addition to the glass, the glassy insulating layer may contain a ceramic filler.

  Further, the light emitting device includes the light emitting element mounting substrate, a light emitting element mounted on the mounting surface of the substrate body, and a phosphor layer covering the light emitting element.

In the light-emitting element mounting substrate of the present invention, the reflective layer containing silver is covered with the vitreous insulating layer, so that the reflective layer can be prevented from corrosion such as oxidation and sulfurization. . Moreover, the curvature after baking can also be prevented.
Further, according to the light emitting device of the present invention, the reflection layer can be prevented from corroding for a long period of time, so that the state of high reflectance can be maintained for a long period of time.

It is an example of sectional drawing of the board | substrate used for this invention. It is an example of sectional drawing which has arrange | positioned the light emitting element to the board | substrate used for this invention. It is an example of sectional drawing of the light-emitting device of this invention.

The light emitting element mounting substrate of the present invention is formed on a substrate body having a mounting surface on which the light emitting element is mounted, a reflective layer containing silver formed on a part of the mounting surface of the substrate body, and the reflective layer. is and a vitreous insulating layer, the vitreous insulating layer is to, by mol% based on oxides, SiO ₂ 30 to 65%, the _Al 2 _{O 3} 1 to _10%, the B 2 _{O 3} It is made of glass containing 0 to 40%, MgO + CaO + SrO + BaO 5 to 50%, ZnO 0 to 20%, Li ₂ O + Na ₂ O + K ₂ O 0 to 1%.

  The substrate body is a flat plate member as shown in FIG. 1 or a member formed with a recess so that the light emitting element mounting surface is positioned one step lower as shown in FIG. The material constituting the substrate is preferably an inorganic material (alumina ceramics, aluminum nitride, LTCC, etc.) for baking the reflective layer and the insulating layer. In particular, in the case of LTCC, the substrate body, the reflective layer, and the insulating layer can be formed by simultaneous firing, and the load on the process when manufacturing the light emitting element mounting substrate can be reduced. Furthermore, in the case of using an LTCC in which a plurality of layers are laminated, an internal wiring layer for feeding can be fired at the same time.

  Silver is mainly used for the reflective layer because of its high reflectance, but metals such as a silver palladium mixture and a silver platinum mixture can also be used. In the case of LTCC in which the sintering of the silver and the sintering of the substrate body are performed together, it is necessary to set the firing temperature in the vicinity of the melting point of silver (962 ° C.) in order to sinter the silver. On the other hand, at a temperature exceeding the melting point of silver, silver is excessively fluidized and deformed, and therefore it is usually preferable to fire at 800 to 900 ° C.

  The glassy insulating layer is a layer that protects the lower reflective layer from corrosion (especially silver oxidation and sulfidation), and is composed of a glass layer or a mixed layer of glass and ceramic filler (glass-ceramic layer). Is done. Glass is a component for densifying the vitreous insulating layer, and is preferably colorless so as not to reduce the reflectance. Note that in this specification, the term “glass” simply refers to amorphous glass, and is referred to as crystalline glass only when it is crystalline glass.

  It is preferable that the glass contained in the vitreous insulating layer can be fired simultaneously with a conductor forming the reflective layer (particularly, one made of silver having a high reflectance). And what does not produce defects, such as a discoloration part and an open pore, does not react with silver especially when baked simultaneously with a silver conductor. That is, when LTCC is used, when the substrate body, the reflective layer, and the insulating layer are fired at the same time, the glass can be sintered and densified in the firing temperature range of 800 to 900 ° C.

  Moreover, generally as a glass which coat | covers a conductor, the alkali free glass which does not contain an alkaline component substantially, or glass with little alkali content is preferable. This is because if the glass contains a large amount of alkali components, the electrical insulation property may be lowered. Further, the glass and silver are likely to react with each other, and silver ions may diffuse into the glass to form a colloid.

  As a result of various studies, the present inventor has found that there is an alkali-free or low-alkali glass composition range in which the glass flows and densifies well during firing and the reaction with silver can be suppressed.

  In the light emitting device of the present invention, examples of the light emitting element include an LED element. More specifically, there is one that excites a phosphor with emitted light to emit visible light, and examples include a blue light emitting type LED element and an ultraviolet light emitting type LED element. However, the light-emitting element is not limited thereto, and various light-emitting elements can be used depending on the use of the light-emitting device, the target light emission color, or the like as long as the light-emitting element can excite the phosphor and emit visible light. Can be used.

  The light emitting device of the present invention is preferably provided with a phosphor layer (see FIG. 3) covering the light emitting element. This phosphor layer is obtained by mixing and dispersing phosphors in a transparent resin such as a silicone resin or an epoxy resin. The phosphor is excited by the light emitted from the light emitting element to emit visible light, and the visible light or the visible light itself emitted from the phosphor by color mixture of the visible light and the light emitted from the light emitting element. As a light emitting device, a desired light emission color is obtained by mixing the colors. The type of the phosphor is not particularly limited, and is appropriately selected according to the target emission color, light emitted from the light emitting element, and the like.

  In addition, the phosphor layer can be separately provided on a coating layer formed so as to directly cover the light emitting element. That is, the phosphor layer is preferably formed on the uppermost layer on the side where the light emitting element of the light emitting device is formed.

  The light-emitting device of the present invention typically has a terminal portion for electrically connecting a light-emitting element on the surface of a substrate body, and a region excluding the terminal portion is covered with a glassy insulating layer. In this case, for example, the light-emitting element is mounted by bonding (die-bonding) the light-emitting element to the substrate with an epoxy resin or a silicone resin, and the electrode on the upper surface of the light-emitting element is attached to the pad portion of the substrate via a bonding wire such as a gold wire. The connection is performed, or a bump electrode such as a solder bump, an Au bump, or an Au—Sn eutectic bump provided on the back surface of the LED chip is flip-chip connected to a lead terminal or a pad portion of the substrate.

  The substrate body is not particularly limited as long as it can be provided with a reflective layer and a glassy insulating layer that protects the reflective layer. Hereinafter, a case where the substrate body is an LTCC substrate will be described.

  The LTCC substrate is a substrate manufactured by baking a mixture of glass powder and ceramic filler such as alumina powder, and can be manufactured by baking simultaneously with a silver conductor.

  Ceramic fillers such as glass powder and alumina powder used for the LTCC substrate are usually used as green sheets. For example, first, glass powder and alumina powder are mixed with a resin such as polyvinyl butyral or acrylic resin and, if necessary, a plasticizer such as dibutyl phthalate, dioctyl phthalate, or butyl benzyl phthalate. Next, a solvent such as toluene, xylene, or butanol is added to form a slurry, and this slurry is formed into a sheet on a film of polyethylene terephthalate or the like by a doctor blade method or the like. Finally, the sheet formed into a sheet is dried to remove the solvent to obtain a green sheet. On these green sheets, wiring patterns, vias, and the like are formed by screen printing using a silver paste as necessary.

The composition of the glass constituting the LTCC substrate is, for example, expressed in mol%, SiO ₂ is 60.4%, B ₂ O ₃ is 15.6%, Al ₂ O ₃ is 6%, CaO is 15%, K ₂ O Is 1% and Na ₂ O is 2%.

  The glass powder used for manufacturing the LTCC substrate is manufactured by pulverizing glass obtained by a melting method. The pulverization method is not limited as long as it does not impair the object of the present invention, and dry pulverization or wet pulverization may be used. In the case of wet pulverization, it is preferable to use water as a solvent. For pulverization, a pulverizer such as a roll mill, a ball mill, or a jet mill can be appropriately used. After pulverization, the glass is dried and classified as necessary.

An example of the ceramic filler is alumina powder. The particle size and shape of the alumina powder are not particularly limited. Typically, those having an average particle diameter D50 of about 1 to ₅ μm are used. An example is AL-45H manufactured by Showa Denko.
The mixing ratio of the glass powder and the alumina powder is typically 40% by mass of the glass powder and 60% by mass of the alumina powder. In the present specification, the 50% particle size (D ₅₀ ) refers to a value measured using a laser diffraction / scattering particle size distribution analyzer.

  The green sheet is processed into a desired shape after firing to form a substrate. In this case, the body to be fired is a laminate of one or more green sheets. The calcination is typically performed at 850 to 900 ° C. for 20 to 60 minutes. A more typical firing temperature is 860 to 880 ° C.

When the reflective layer is formed at the same time, it can be sintered at 900 ° C., which is the upper limit of the green sheet firing temperature. However, if it exceeds 900 ° C., the silver or silver-containing conductor softens during firing and the shape of the conductor pattern and vias is maintained. There is a risk that it will not be possible. Preferably it is 880 degrees C or less. More preferably, it is 870 degreeC or less.
It is preferable that the reflective layer containing silver formed on the substrate surface does not contain other inorganic components from the viewpoint of reflectivity. The reflective layer mainly reflects light emitted from the light emitting element mounted on the substrate body.

Next, the vitreous insulating layer will be described.
The glassy insulating layer is preferably a single glass layer or a layer containing glass and a ceramic filler.

  The thickness of the glassy insulating layer is typically 5 to 30 μm. If it is less than 5 μm, the covering property may be insufficient, so that it is preferably 5 μm or more. If it exceeds 30 μm, the heat dissipation of the light emitting element may be hindered and the light emission efficiency may be reduced.

  The method for forming the glassy insulating layer is not particularly limited as long as the layer having a thickness of 5 to 30 μm can be formed flat. Typically, the screen is formed by pasting a single glass or a mixture of glass and ceramic filler into a screen. It is formed by printing and baking.

  In this invention, it is preferable to contain 50% or more of glass by volume% display in a vitreous insulating layer. If it is less than 50%, sintering at the time of firing becomes insufficient, and the covering property may be impaired. In order to improve sinterability, it is more preferable to contain 70% or more. Further, it contains 50% or less of ceramic filler. The ceramic filler content is typically 5% or more. By containing a ceramic filler, the strength of the vitreous insulating layer may be increased. Moreover, the heat dissipation of a glassy insulating layer may be able to be made high.

  The ceramic filler is exemplified by alumina and silica, but is not limited as long as it does not cause absorption that impairs the reflectance (white or transparent).

  The glass of the vitreous insulating layer preferably has a Tg of 460 to 780 ° C. Tg can be observed, for example, as the temperature of the shoulder of the first bent portion when differential thermal analysis measurement is performed at a temperature increase rate of 10 ° C./min.

  The glass of the vitreous insulating layer preferably has a Ts of 700 to 900 ° C. Here, Ts can be observed as the temperature of the fourth bent portion when differential thermal analysis measurement is performed up to 1000 ° C. under a temperature rising rate of 10 ° C./min.

  The glass of the vitreous insulating layer is preferably one that does not crystallize in the firing step. Those having Tc of 900 ° C. or higher or those in which Tc cannot be observed are preferable. When Tc is less than 900 ° C., crystallization is likely to occur in the firing step, which may cause warpage of the substrate. Here, Tc refers to the temperature of an exothermic peak observed at a temperature higher than Tg when differential thermal analysis measurement is performed up to 1000 ° C. under a temperature rising rate of 10 ° C./min.

  Next, the composition of the glass that can be used in the present invention will be described.

The SiO ₂ 30 to 65% by mol% based on oxides, the _{Al 2 O 3 1~10%, B} 2 O 3 of 0~40%, MgO + CaO + SrO + BaO 5-50%, 0-20% of ZnO, It is a glass containing 0 to 1% of Li ₂ O + Na ₂ O + K ₂ O.

SiO ₂ is a glass network-forming oxide and an essential component. If the content of SiO ₂ is less than 30%, the glass may become unstable, or the thermal stability or chemical stability of the glass may be insufficient. If the SiO ₂ content exceeds 65%, the softening point (Ts) of the glass becomes too high, and a dense vitreous insulating layer may not be formed.

Al ₂ O ₃ is an essential component that increases the stability of the glass and is contained in an amount of 1% or more. If the content is less than 1%, the glass may become unstable. Preferably it is 2% or more. On the other hand, if the content of Al ₂ O ₃ is more than 10%, Ts may be too high. Moreover, Tc becomes low, and there is a possibility that crystallization is likely to occur in the firing temperature range. Further, when used for insulation of a silver conductor and fired at the same time, silver reflectance tends to decrease the silver reflectance. The content of Al ₂ O ₃ is preferably 8% or less.

A further description will be given of the relationship of Al ₂ O _{3 to} the silver coloring behavior. The generation mechanism of silver coloring can be explained as follows. First, in the vitreous insulating layer that is fired in such a manner as to cover the reflective layer containing silver, silver diffuses into the glass of the vitreous insulating layer as it is fired. Silver in the glass is considered to be present in the form of silver ions and is usually Ag ⁺ . In addition, silver ions move and collect in the glass and, when reduced, become Ag ⁰ and, when colloidal, cause light absorption. This light absorption is detected as so-called silver coloring.

  Considering in this mechanism, if silver is present in the glass in the form of silver ions, no light absorption is caused and no silver color is detected. That is, it can be said that keeping silver in the glass as silver ions is an effective means for suppressing silver color development.

In the case of the present invention, glass having SiO ₂ as a skeleton is selected because it is easy to ensure stability of glass, availability of raw materials, and chemical durability required in a plating process. Regarding the relationship between the alkali metal component in the glass having SiO ₂ as a skeleton and Al ₂ O ₃ , the following is known. Here, M represents an alkali metal atom. First, when an alkali component is introduced into a glass having a SiO ₂ skeleton, alkali metal atoms break the bond between silicon atoms and oxygen atoms in the glass, that is, Si—O—Si crosslinks, and Si—O— ⁻ : Enters in the form of M ⁺ ionic bonds, and generates so-called non-bridging oxygen.

When Al ₂ O ₃ is introduced here, first, Al ³⁺ that is an aluminum ion attracts non-bridging oxygen in the glass and takes the form of [AlO ₄ ] having a four-coordinate structure, and the central Al is a negative charge. It becomes a tinged shape. For this charge compensation, M ⁺ (alkali metal ion) having a positive charge is attracted. B (boron) is also known as an element having a similar structure, but it is said that Al (aluminum) preferentially takes this structure in preference to B. When this structure is adopted, the number of non-bridging oxygen in the structure of the entire glass is reduced, and the structure of the glass network is strengthened.

Here, considering Ag (silver), Ag also takes a monovalent valence, like an alkali metal atom, and when it exists as an ion in glass, it becomes Ag ⁺ and behaves like an alkali metal atom. It is inferred to show. That is, Al ³⁺ attracts non-bridging oxygen in the glass and takes the form of four-coordinate [AlO ₄ ], and the central Al becomes negatively charged. For this charge compensation, Ag ⁺ (silver ions) having a positive charge is attracted. Since silver ions in the glass do not cause color development, it is considered that silver color formation is unlikely to occur when this structure that can exist stably with silver ions is adopted.

However, when Al ₂ O ₃ is excessive, it is known that Al has a six-coordinate structure in glass and behaves as a so-called modifying element. In this case, since Al behaves in the direction of increasing non-bridging oxygen, the glass has a structure with many gaps. Further, Al does not attract ions having positive charges such as Ag ⁺ . In other words, silver ions cannot be stabilized in the glass. At this time, it is presumed that alkali metal atoms and silver easily move in the glass, and silver is likely to collect and colloid. The inventor has found that if the sum of the SiO ₂ content (%) and the triple Al ₂ O ₃ content (%) is too large, silver coloring tends to occur. That is, the value of SiO ₂ + 3 × Al ₂ O ₃ is preferably 90% or less. If it exceeds 90%, silver coloring tends to occur.

  BaO is not an essential component, but has the effect of stabilizing the glass and lowering Ts, and it is preferable to add a small amount. Specifically, it is preferably 3% or more, more preferably 5% or more.

  MgO, CaO, SrO and ZnO are not essential components, but are components that lower the melting temperature of the glass and lower Ts, and preferably contain 5% or more in total with BaO, and contain 8% or more. More preferably. If it is less than 5%, the glass may become unstable. Alternatively, Ts may increase and it may be difficult to form a dense insulating layer. MgO, CaO, SrO, BaO, ZnO can be contained up to 50% in total. If it exceeds 50%, the glass tends to be unstable, and there is a possibility that the color tends to develop when the glass is coated on the silver conductor and fired at the same time. Preferably it is 40% or less. Further, if the total content of MgO, CaO, SrO, and BaO exceeds 35%, crystallization may easily occur.

  When ZnO is contained, the content is preferably 20% or less. If it exceeds 20%, chemical durability may be insufficient.

B ₂ O ₃ is not essential, but it is a component that increases the stability of the glass and lowers Ts, and can be contained up to 40%. If it exceeds 40%, chemical durability such as acid resistance may be insufficient.

When an alkali metal oxide such as Li ₂ O, Na ₂ O, or K ₂ O is contained, the total content is 1% or less. More preferably, it is alkali-free glass. That is, it is preferable not to contain an alkali metal oxide substantially. Glass containing these alkali components may have insufficient electrical insulation when used for insulation of a conductor such as silver. Further, when glass is applied onto a silver conductor and fired at the same time, an undesirable reaction (silver coloring) may occur between silver and glass.

  Although the glass in the present invention essentially contains the above components as a main component, it may contain other components as long as the object of the present invention is not impaired. When such components are contained, the total content of these components is preferably 10% or less. However, lead oxide is not contained.

  The reflectance of the light emitting element mounting substrate on which the vitreous insulating layer of the present invention is formed is preferably 85% or more, more preferably 88% or more, and further preferably 90% or more.

  A glass raw material was prepared and mixed so as to have the composition shown in mol% for Examples 1 to 8 shown in Table 1, and the mixed raw material was put in a platinum crucible and melted at 1500 to 1600 ° C. for 60 minutes, and then the molten glass was obtained. Sink out and cool. The obtained glass was pulverized with an alumina ball mill for 20 to 60 hours using water as a solvent to obtain glass powder. Examples 1-6 are the glass of an Example, Example 7 is the glass of a comparative example. Example 8 is an example in which an alumina filler (AA-2 manufactured by Sumitomo Chemical) was added to the glass powder of Example 4. The volume ratio of glass to alumina is shown in the glass column and alumina column in the table.

The average particle diameter D ₅₀ (unit: μm) of each glass powder was measured using SALD2100 manufactured by Shimadzu Corporation. Were each in the range of _D 50 = 1 to 3 [mu] m. The softening point Ts (unit: ° C.) was measured up to 1000 ° C. at a temperature rising rate of 10 ° C./min using a thermal analyzer TG-DTA2000 manufactured by Bruker AXS. In any of Examples 1 to 8, no crystal peak was observed during Ts measurement.

  For Examples 1 to 4 and 7, only each glass powder was used. For Example 8, a mixed powder obtained by adding an alumina filler to glass powder was 70% by mass%, and the vehicle component obtained by melting a resin in a solvent was 30%. The mixture was kneaded in a porcelain mortar for 1 hour, and further dispersed three times with a three roll to produce a glass paste.

  The silver paste is prepared by mixing conductive powder (S400-2 manufactured by Daiken Chemical Industry Co., Ltd.) and ethyl cellulose at a mass ratio of 85:15, and dispersing in a solvent (α terpineol) with a solid mass% display concentration of 85%. After that, it was kneaded in a porcelain mortar for 1 hour, and further dispersed three times with three rolls.

  The silver paste is printed on the LTCC green sheet, and after drying, the glass paste is printed on the silver paste. This is held at 550 ° C. for 5 hours to decompose and remove the resin component, and then held at 870 ° C. for 30 minutes and fired. Went. The reflectance of the surface of the obtained LTCC substrate was measured. The reflectance was measured using a spectroscope USB2000 and a small integrating sphere ISP-RF manufactured by Ocean Optics, and the average value of 400 to 800 nm in the visible light region was calculated as the reflectance (unit:%). The results are shown in the table.

  Since the reflectance of the silver conductor layer without an insulating layer is 95%, the reflectance is preferably as close to that as possible. Considering the correlation between the result of measuring the amount of light and placing the LED on the actual package and the reflectance of the measurement by this method, if the reflectance is less than 85%, the light from the light emitting element cannot be reflected efficiently, so the insulating layer I thought it was not preferable.

  It can be used for backlights of mobile phones and large LCD TVs.

1: LTCC substrate 2: Conductor layer (reflection layer)
3: Glassy insulating layer 4: Via conductor 5: Sealing resin (phosphor layer)
6: Light emitting element 7: Bonding wire 8: Gold plating layer

Claims (6)

A substrate body having a mounting surface on which the light emitting element is mounted; a reflective layer containing silver formed on a part of the mounting surface of the substrate body; and a vitreous insulating layer formed on the reflective layer. ,
The vitreous insulating layer, as represented by mol% based on oxides, the SiO ₂ 30 to 65%, the _{Al 2 O 3 1~ 8%,} B 2 O 3 of 0~40%, MgO + CaO + SrO + BaO 5-50% A substrate for mounting a light-emitting element, characterized by being formed of glass having a softening point of 900 ° C. or lower, containing 0 to 15 % of ZnO and 0 to 1% of Li ₂ O + Na ₂ O + K ₂ O.   The light emitting element mounting substrate according to claim 1, wherein the glass contained in the glassy insulating layer is a glass having thermal characteristics of a transition point of 460 to 780 ° C., a softening point of 700 to 900 ° C., and a crystallization point of 900 ° C. or more.   The light emitting element mounting substrate according to claim 1, wherein the glassy insulating layer contains a ceramic filler in addition to the glass.   The light emitting element mounting substrate according to claim 1, wherein a terminal portion for the light emitting element is formed on the substrate body, and the insulating layer is formed in a region excluding the terminal portion.   The light emitting element mounting substrate according to any one of claims 1 to 4, wherein the substrate body has a recess, and the bottom surface of the recess is a light emitting element mounting surface.   A light-emitting device having a phosphor layer on which a light-emitting element is mounted on the glassy insulating layer of the light-emitting element mounting substrate according to claim 1.

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