TWI648884B - Substrate for light-emitting element and light-emitting device - Google Patents

Abstract

The present invention provides a substrate for a light-emitting element in which cracking of a substrate caused by a heat sink having an inclined portion or a step portion on a side surface is suppressed. The substrate for a light-emitting element of the present invention includes a substrate, a heat sink, a first coating layer, and a second coating layer. The base body has a first main surface and a second main surface disposed on the opposite side. The heat sink is disposed inside the base and has a plurality of constituent units divided in the thickness direction of the base. The first coating layer is disposed on the first main surface, and covers an end surface on the first main surface side of the second constituent unit of the heat dissipating body disposed on the first main surface side, and an outer edge thereof is disposed on an end surface of the second constituent unit The outer edge of the outer edge is formed. The second coating layer is disposed between the plurality of constituent units of the heat radiating body, and covers an end surface of the first main surface side of the first constituent unit disposed on the second main surface side of the constituent units, and the outer edge is disposed at the outer edge The end surface on the first main surface side of the constituent unit is formed on the outer side of the outer edge.

Description

Substrate for light-emitting element and light-emitting device

The present invention relates to a substrate for a light-emitting element and a light-emitting device.

In recent years, with the high brightness and whiteness of a light-emitting diode (LED) element, a light-emitting device using an LED element in a backlight of a mobile phone or a large-sized liquid crystal TV (television) has been used. In such a light-emitting device, since the luminance of the LED element is increased, the amount of heat generation is increased and the temperature is increased, so that sufficient luminance of the light is not necessarily obtained.

On the other hand, in order to suppress the temperature rise of the light-emitting device, it is known to provide a heat sink so as to penetrate the substrate on which the light-emitting element is mounted. Further, it is known that the contact area between the heat sink and the substrate mainly composed of the substrate is increased by providing the inclined portion or the step portion on the side surface of the heat sink, and the adhesion strength between the heat sink and the substrate is ensured. The inclined portion and the step portion are generally configured such that the main surface side of one of the light-emitting elements is directed toward the other main surface side opposite to each other, and the cross-sectional area (perpendicular to the thickness direction) is increased. In addition, as a heat sink having a step portion, a two-stage structure is known (for example, refer to Patent Document 1).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2006-093565

However, when the inclined portion or the step portion is provided on the side surface of the heat sink, the difference between the thermal expansion rates of the substrate and the heat sink is easy to start from the side of the heat sink. The base of the edge is broken. For example, as a heat sink, a two-stage structure in which a heat sink having a small cross-sectional area and a heat sink having a large cross-sectional area are disposed in order from one main surface side of the light-emitting element. In such a case, it is easy to cause a crack in the thickness direction toward the base surface from the corner portion formed by the boundary between the surface and the side surface on the main surface side of the heat dissipating body having a large cross-sectional area as the starting point. Further, on the main surface, it is easy to use the heat sink as a starting point, and the base body around the surface is broken in the surface direction.

In order to solve the above problems, an object of the present invention is to provide a substrate for a light-emitting element and a light-emitting device in which cracking of a substrate caused by an inclined portion or a step portion provided on a side surface of a heat sink is suppressed.

The substrate for a light-emitting element of the present invention has a substrate, a heat sink, a first coating layer, and a second coating layer. The base body has a plate shape, and has a first main surface on which the light emitting element is mounted and a second main surface disposed on the opposite side of the first main surface. The heat radiating body is disposed inside the base body, and the surface of the end surface on the second main surface side is larger than the area of the end surface on the first main surface side, and has a plurality of constituent units divided in the thickness direction of the base body. The first coating layer is disposed on the first main surface, and covers the end surface on the first main surface side of the second constituent unit of the heat dissipating body disposed on the first main surface side, and the outer edge of the first coating layer is disposed in the second configuration. The end surface on the first main surface side of the unit is formed on the outer side of the outer edge. The second coating layer is disposed between the plurality of constituent units of the heat radiating body, and covers an end surface of the first main surface side of the first constituent unit disposed on the second main surface side of the second constituent unit in the constituent unit The outer edge of the second coating layer is disposed on the outer side of the outer edge formed by the end surface on the first main surface side of the first constituent unit.

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

In the substrate for a light-emitting element of the present invention, the first coating layer is provided on one side of the main surface on which the light-emitting element is mounted so as to extend over the substrate of the heat sink and the peripheral portion thereof, and the second coating layer is The structure is disposed inside the base body of the heat sink and its peripheral portion. Thereby, even when the inclined portion or the step portion is provided on the side surface of the heat sink, the crack of the base body starting from the heat sink is suppressed.

10‧‧‧Substrate for light-emitting components

11‧‧‧ base

11a‧‧‧1st main face of the base

11b‧‧‧2nd main face of the base

12‧‧‧ Heat sink

13‧‧‧1st coating

14‧‧‧2nd coating

15‧‧‧Wiring conductor

16‧‧‧Shell

17, 18‧‧‧ External electrodes

20‧‧‧Lighting device

21‧‧‧Lighting elements

22‧‧‧bonding line

23‧‧‧ Sealing layer

31‧‧‧1st straight line

32‧‧‧2nd line

111‧‧‧1st matrix

112‧‧‧2nd matrix

121‧‧‧1st building block

122‧‧‧2nd building block

From each side other than L ₁ ‧‧‧ constituting the second end surface of the first main surface side of the unit formed by the outside edge of the respective sides of the first edge of the covering layer

L ₂ ‧‧‧ The distance between each side of the outer edge formed by the end face on the first main surface side of the first constituent unit and the outer edge of the second coating layer

Fig. 1 is a plan view showing a substrate for a light-emitting element of the first embodiment.

Fig. 2 is a bottom view of the substrate for a light-emitting element shown in Fig. 1;

Fig. 3 is a cross-sectional view of the substrate for a light-emitting element shown in Fig. 1 as viewed in the direction of arrows AA.

Fig. 4 is an explanatory view showing the angle θ of the side surface of the heat sink.

Fig. 5 is a plan view showing a positional relationship between a heat radiating body and a first covering layer.

Fig. 6 is a plan view showing a positional relationship between a heat radiating body and a second covering layer.

Fig. 7 is a plan view showing a first embodiment of the light-emitting device.

Fig. 8 is a cross-sectional view of the light-emitting device shown in Fig. 7 as viewed in the direction of arrows BB.

FIG. 9 is a plan view showing a substrate for a light-emitting element of a second embodiment.

Fig. 10 is a cross-sectional view of the substrate for a light-emitting element shown in Fig. 9 as seen in the direction of arrows CC.

Hereinafter, an embodiment of a substrate for a light-emitting element will be described.

Fig. 1 is a plan view showing a first embodiment of a substrate for a light-emitting element. Fig. 2 is a bottom view of the substrate for a light-emitting element shown in Fig. 1; Fig. 3 is a cross-sectional view of the substrate for a light-emitting element shown in Fig. 1 as viewed in the direction of arrows AA.

The light-emitting element substrate 10 has a plate-like base 11 as shown in FIG. 3, for example. The base 11 has a first main surface 11a on which the light-emitting elements are mounted, and a second main surface 11b disposed on the opposite side of the first main surface 11a. Inside the base 11, a heat sink 12 including two constituent units 111 and 112 which are divided in the thickness direction of the base 11 is provided. The first covering layer 13 is provided on the first main surface 11a. A second coating layer is disposed between each of the constituent units 111 and 112 of the heat sink 12 14.

Further, the wiring conductor 15 (FIG. 1) is provided on the first main surface 11a, and the casing 16 may be provided so as to surround the first cladding layer 13 and the wiring conductor 15. External electrodes 17 and 18 are provided on the second main surface 11b. A through conductor (not shown) that connects the wiring conductor 15 and the external electrode 17 is provided inside the base 11.

The base 11 has a square cross-sectional shape, for example, in a cross section perpendicular to the thickness direction. Further, the base 11 has, for example, the first base 111 and the second base 112 in this order from the second main surface 11b side. In addition, the thickness direction means a direction perpendicular to the second main surface 11b from the first main surface 11a.

Further, the thickness of the base 11 is not particularly limited, but is usually 0.20 mm or more and 0.60 mm or less.

The thickness of each of the first base 111 and the second base 112 is preferably 0.10 mm or more. When the thickness is 0.10 mm or more, the rationality of the green sheet at the time of manufacture becomes good. Further, in the case where the thickness is 0.10 mm or more, the heat sink 12 is easily formed on the green sheet. The thickness of each of the first base 111 and the second base 112 is preferably 0.15 mm or more. On the other hand, the thickness of each of the first base 111 and the second base 112 can be set to 0.30 mm or less or 0.25 mm or less. Further, when the base 11 includes the first base 111 and the second base 112, the thickness of the first base 111 and the thickness of the second base 112 are preferably in the range of 3:7 to 7:3, more preferably 4 Range of 6~6:4, especially 5:5 (ie the same thickness).

The base 11 contains, for example, an inorganic insulating material. Examples of the inorganic insulating material include alumina, aluminum nitride, and glass ceramics. The glass ceramic is a sintered body of a glass ceramic composition containing a glass powder and a ceramic powder, and examples thereof include low temperature co-fired ceramics (LTCC).

The thermal conductivity of aluminum nitride is about 200 W/(m.K), the thermal conductivity of alumina is about 20 W/(m.K), and the thermal conductivity of glass ceramic is about 4 W/(m.K). The thermal conductivity of alumina and glass ceramics is much lower than that of aluminum nitride. Therefore, when the inorganic insulating material is alumina or glass ceramic, the effect of providing the heat sink 12 is large.

Among these, glass ceramics are preferred insofar as the baking temperature is low. For example, in the substrate 10 for a light-emitting element, a silver reflective film is formed on the first main surface 11a side of the substrate 11 in order to increase the reflectance of light. Since the glass ceramic has a low calcination temperature, the glass reflective film can be fired at the same time as the glass ceramic is fired. Further, from the viewpoint that the glass ceramics have better workability than alumina, the inorganic insulating material is also preferably a glass ceramic.

For example, as shown in FIG. 3, the heat sink 12 is provided inside the base 11 so as to extend in the thickness direction. Generally, the heat radiating body 12 has a square cross-sectional shape in a cross section perpendicular to the thickness direction. Further, the area of the end surface on the second main surface 11b side of the heat radiating body 12 is larger than the area of the end surface on the first main surface 11a side of the heat radiating body 12. When the area on the side of the second main surface 11b is larger than the area on the side of the first main surface 11a, when the heat of the light-emitting element is transmitted from the first main surface 11a side to the second main surface 11b side, the surface direction (and thickness) When the direction is orthogonal to the plane direction, the heat dissipation is improved. Further, the area of the cross section at any position in the thickness direction of the heat radiating body 12 is preferably the same as or larger than the area of the cross section located closer to the first main surface 11a than the cross section. In addition, in this specification, unless otherwise indicated, the "sectional area" and the "area of the cross-section" mean the area of the cross section perpendicular to the thickness direction, and the "cross-sectional shape" means the cross section perpendicular to the thickness direction. shape.

The area of the end surface on the first main surface 11a side of the heat sink 12 is preferably 0.20 mm ² or more, and more preferably 0.25 mm ² or more from the viewpoint of improving heat dissipation. On the other hand, the area of the radiator 12 of the side end surface 11a of the first main surface is preferably 0.60mm ² or less, more preferably 0.55mm ² or less.

In addition, the area of the end surface on the first main surface 11a side of the heat radiating body 12 is preferably smaller than the area of the mounting surface of the light emitting element (hereinafter referred to as the "area of the light emitting element"), that is, the mounting of the light emitting element in the substrate for the light emitting element. The area of the department. As described below, the outer edge of the first covering layer 13 is provided on the outer side of the outer edge formed on the end surface of the heat radiating body 12 on the first main surface 11a side. In this case, when the end surface area of the heat radiating body 12 on the first main surface 11a side is larger than the area of the light emitting element, the first covering layer 13 is inevitably self-illuminating in plan view (when viewed from the first main surface 11a side). element Extend. In the case where there is a protruding portion, if a layer that absorbs light is formed in this portion, light of the light-emitting element is absorbed, so that the light use efficiency is lowered. Therefore, in order not to absorb the light of the light-emitting element, it is preferable that the area of the end surface on the first main surface 11a side of the heat sink 12 is smaller than the area of the light-emitting element.

The heat radiating body 12 has a stepped portion on the side surface, for example, and the cross-sectional area is gradually increased from the first main surface 11a side toward the second main surface 11b side. Further, for example, as shown in FIG. 3, the heat sink 12 includes a plurality of constituent units divided by a plane perpendicular to the thickness direction, and has the first constituent unit 121 and the second constituent unit in this order from the second main surface 11b side. 122. The cross-sectional area of the first constituent unit 121 is larger than the cross-sectional area of the second constituent unit 122. The thickness of the first constituent unit 121 is generally substantially the same as the thickness of the first base 111. Similarly, the thickness of the second constituent unit 122 is generally substantially the same as the thickness of the second base 112.

Moreover, the ratio (V ₂ /V ₁ ) of the volume (V ₂ ) of the heat radiating body 12 to the total volume (V ₁ ) of the base 11 and the member disposed therein is preferably 10% by volume or more. Further, examples of the member include the heat sink 12, the second covering layer 14, and a through conductor (not shown). When the ratio (V ₂ /V ₁ ) is 10% by volume or more, the volume of the heat sink 12 is sufficiently large, so that heat dissipation is improved.

In addition, when the ratio (V ₂ /V ₁ ) is 10% by volume or more, in the prior configuration in which the first covering layer 13 and the second covering layer 14 are not provided, the base body 11 is easily formed with the heat radiating body 12 as The break of the starting point. In the substrate for a light-emitting element of the embodiment, since the coating layer is provided, even if the ratio (V ₂ /V ₁ ) is 10% by volume or more, the occurrence of cracking can be suppressed, and good heat dissipation can be obtained.

The ratio (V ₂ /V ₁ ) of the heat radiating body 12 is more preferably 15% by volume or more. On the other hand, the ratio (V ₂ /V ₁ ) is preferably 30% by volume or less. When the ratio (V ₂ /V ₁ ) exceeds 30% by volume, the volume (V ₁ ) is relatively decreased, and the strength of the substrate 11 is relatively lowered, even if the first coating layer 13 and the second coating layer 14 are provided. The base body 11 is broken by the heat sink 12 as a starting point. Further, the ratio (V ₂ /V ₁ ) is more preferably 25% by volume or less.

4 is an explanatory view for explaining an angle θ of a side surface of the heat sink 12. When the heat sink 12 has a stepped portion on the side surface, the angle θ is the first straight line 31 extending in the thickness direction of the base 11 and the end surface passing through the second main surface 11b side of each of the constituent units 121 and 122. The angle formed by the second straight line 32 of the corner formed by the boundary between the side faces. The angle θ is preferably 20° or more. When the angle θ is 20° or more, the area of the end surface on the second main surface 11b side is sufficiently larger than the area of the end surface on the first main surface 11a side, so that heat dissipation is improved. The angle θ is more preferably 30° or more. On the other hand, from the viewpoint of heat dissipation, it is sufficient that the angle θ is about 70°. The angle θ is more preferably 60° or less. Generally, the angle θ is particularly preferably about 45°.

Further, in the heat radiating body 12, the radius of curvature of the corner portion formed by the two side faces of the cross-sectional shape is preferably 0.03 mm or more. That is, in the case where the cross section perpendicular to the thickness direction of the heat radiating body 12 is a square, it is preferable that the corners of the corners of the four corners of the square have a curvature radius of 0.03 mm or more. When the radius of curvature is 0.03 mm or more, the crack of the base 11 starting from the apex of the corner is suppressed. The radius of curvature is more preferably 0.05 mm or more. On the other hand, when the radius of curvature is too large, the cross-sectional shape of the heat sink 12 is nearly circular, so that the difference from the shape of the cross-sectional shape (outer edge) of the base 11 becomes large, and the crack of the base 11 is likely to occur. Therefore, the radius of curvature is preferably 0.40 mm or less, more preferably 0.35 mm or less.

The constituent material of the heat sink 12 is preferably a metal material having a high thermal conductivity. Examples of such a metal material include metals containing copper, silver, gold, and the like as a main component. Specifically, silver, silver or platinum, or a metal containing silver and palladium is preferred. In the present specification, the term "a component as a main component of a constituent material" means that the component is contained in an amount of more than 50% by mass based on the total amount of the constituent materials. Further, the constituent material of the first constituent unit 121 and the constituent material of the second constituent unit 122 may be the same or different. In the case where the constituent material of the substrate 11 is other than the glass ceramic, the constituent material of the heat sink 12 is preferably a high melting point metal such as tungsten or molybdenum, from the viewpoint of suppressing deformation during firing or the like.

The first coating layer 13 is disposed on the surface of the base 11 on the side of the first main surface 11a. First covering layer 13 For example, the second constituent unit 122 having a square cross-sectional shape has a square cross-sectional shape. The first coating layer 13 covers the end surface on the first main surface 11a side of the second structural unit 122, and the outer edge of the first coating layer is disposed on the outer edge of the end surface on the first main surface 11a side of the second structural unit 122. Outside. The base 11 (the second substrate) of the peripheral portion of the second constituent unit 122 is disposed on the outer side of the outer edge of the second constituent layer 122 on the first main surface 11a side. 112) is covered by the first covering layer 13. Thereby, the crack in the surface direction of the base 11 starting from the second constituent unit 122 is suppressed.

FIG. 5 is a plan view showing the positional relationship between the second constituent unit 122 and the first covering layer 13. The distance L ₁ between each side (square) of the outer edge of the end surface on the first main surface 11a side of the second constituent unit 122 and each side (square) of the outer edge of the first cladding layer 13 is preferably 0.03, respectively. Mm or more. When the distance L ₁ is 0.03 mm or more, the base 11 (second base 112 ) of the peripheral portion of the second constituent unit 122 is sufficiently covered by the first covering layer 13 . Thereby, the crack in the surface direction of the base 11 starting from the second constituent unit 122 is further suppressed. The distance L ₁ is more preferably 0.05 mm or more. On the other hand, when the distance L ₁ is excessively large, the first covering layer 13 protrudes from the light-emitting element (the mounting portion). If there is an extended portion, there is a flaw in which light of the portion of the light-emitting element is absorbed as described above. Therefore, in order not to absorb the light of the light-emitting element, the distance L _{1 is} preferably 0.30 mm or less, more preferably 0.25 mm or less.

In consideration of the relationship between the mounting portion of the light-emitting element and the second constituent unit 122, the area of the end surface on the first main surface 11a side of the second constituent unit 122 is preferably smaller than the area of the mounting portion of the optical element, and the second constituent unit The outer edge formed by the end surface on the first main surface 11a side of the 122 is not overlapped with the outer edge of the mounting portion of the light-emitting element, and is located inside. In the example of FIG. 5, the outer edge of the first covering layer 13 is represented as a square, but the first coating layer is provided as long as the distance L ₁ from the outer edge of the second constituent unit 122 satisfies the specific range as described above. The outer edge of 13 is not particularly limited to a square, and any shape can be applied.

When the area of the first covering layer 13 is larger than the area of the light-emitting element and there is a portion where the self-emitting element protrudes, if a layer that absorbs light is formed in the portion, the light of the light-emitting element is Absorption, the efficiency of light utilization is reduced. Therefore, in order not to absorb the light of the light-emitting element, it is preferable that the area of the first covering layer 13 is the same as or smaller than the area of the light-emitting element, and the outer edge of the first covering layer 13 and the light-emitting element (in plan view) The outer edge of the mounting portion is the same or is located further inside. Here, the term "inside" is not limited to the case where the outer edge of the first covering layer 13 is not overlapped with the outer edge of the mounting portion of the light-emitting element and is located inside, and the outer edge of the first covering layer 13 is also included. Some of them overlap with one of the outer edges of the mounting portion of the light-emitting element and are located inside.

In addition, as the layer for absorbing light, a protective layer which is formed so as to cover the entire surface of the first covering layer 13 in order to suppress corrosion of the first covering layer 13 is exemplified. As the protective layer, a metal plating layer having a nickel-plated (Ni) layer or a gold-plated (Au) layer-plated Ni/Au layer is sequentially laminated from the surface side of the first coating layer 13.

The thickness of the first coating layer 13 is preferably 5 μm or more, and more preferably 10 μm or more from the viewpoint of suppressing cracking of the substrate 11 caused by the second constituent unit 122. Further, the thickness of the first covering layer 13 is preferably 20 μm or less, and more preferably 15 μm or less from the viewpoint of reducing the influence on the substrate 11 caused by thermal expansion.

The constituent material of the first coating layer 13 is, for example, a metal material or a resin material, and is preferably a metal material from the viewpoint of suppressing the cracking of the base 11 and having high heat conductivity. Examples of such a metal material include metals containing copper, silver, gold, and the like as a main component. Specifically, silver, silver or platinum, or a metal containing silver and palladium is preferred. In addition, when the constituent material of the base 11 is other than glass ceramics, a high melting point metal such as tungsten or molybdenum is preferable from the viewpoint of suppressing deformation during baking and the like. The first covering layer 13 preferably has a dense structure including the metal materials. By having a dense structure, the effect of suppressing the crack of the base 11 is large. The dense structure is manufactured by adjustment of the firing conditions. Further, examples of the resin material include an acrylic resin, an epoxy resin, and an anthrone resin.

The second coating layer 14 is disposed inside the base 11, and the first constituent unit 121 and the second constituent sheet Between the levels 122. The second covering layer 14 is fitted with a heat radiating body 12 having a square cross-sectional shape, for example, having a square cross-sectional shape. The second coating layer 14 covers the end surface on the first main surface 11a side of the first constituent unit 121 disposed on the second main surface 11b side. Moreover, the outer edge of the second covering layer 14 is disposed on the outer side of the outer edge formed on the end surface of the first main surface 11a of the first structural unit 121.

The base 11 (the first substrate) of the peripheral portion of the first constituent unit 121 is formed on the outer side of the outer edge of the first constituent surface 121 on the outer surface of the first constituent surface 121. 111) is covered by the second covering layer 14. In this manner, the thickness direction of the base 11 (second base 112) facing the first main surface 11a from the corner formed by the boundary between the end surface on the first main surface 11a side of the first constituent unit 121 and the side surface is suppressed. The rupture.

FIG. 6 is a plan view showing a positional relationship between the first constituent unit 121 and the second covering layer 14. The distance L ₂ between the (square) side of the outer edge formed by the end surface on the first main surface 11a side of the first constituent unit 121 and the (square) side of the outer edge of the second cladding layer 14 is preferably respectively It is 0.05 mm or more. When the distance L ₂ is 0.05 mm or more, the first constituent unit 121 and the base 11 (the first base 111) of the peripheral portion thereof are sufficiently covered by the second covering layer 14 . Thereby, cracking in the thickness direction of the base 11 (second base 112) starting from the corner portion on the first main surface 11a side of the first constituent unit 121 is further suppressed. The distance L ₂ is more preferably 0.10 mm or more. On the other hand, when the distance L _{2 is} increased, the first base body 111 and the second base body 112 are easily peeled off. From the viewpoint of suppressing such peeling, the distance L _{2 is} preferably 0.35 mm or less, more preferably 0.30 mm or less.

In the example of FIG. 6, the outer edge of the second covering layer 14 is shown as a square, but the distance L ₂ from the outer edge formed by the end surface on the first main surface 11a side of the first constituent unit 121 satisfies the above. In the specific range described above, the outer edge of the second coating layer 14 is not particularly limited to a square shape, and any shape may be applied. Further, the cross-sectional area of the first constituent unit 121 is not particularly limited, and is larger than the area of the mounting portion of the optical element because it can improve the heat dissipation effect.

The thickness of the second covering layer 14 can be the same as that described for the first covering layer 13.

The constituent material of the second covering layer 14 can be the same as that described for the first covering layer 13.

In addition, the shape of the casing 16, the wiring conductor 15, the external electrodes 17, 18, and the through conductor (not shown) is not limited, and a shape or the like may be selected as needed.

The constituent material of the casing 16 is preferably the same material as the constituent material of the base 11 from the viewpoint of productivity and the like. As such a material, alumina, aluminum nitride, glass ceramics or the like is preferable, and alumina or glass ceramic is more preferable. For example, a glass ceramic such as a low temperature co-fired ceramic (LTCC) is preferable.

The constituent materials of the wiring conductor 15, the external electrodes 17, 18, and the through conductor are preferably the same metal materials as those of the heat sink 12, the first covering layer 13, and the second covering layer 14. Examples of such a metal material include metals containing copper, silver, gold, and the like as a main component. Specifically, silver, silver or platinum, or a metal containing silver and palladium is preferred. In addition, when the constituent material of the base 11 is other than glass ceramics, a high melting point metal such as tungsten or molybdenum is preferable from the viewpoint of suppressing deformation during baking and the like.

In the above, the substrate for a light-emitting element of the embodiment has been described as an example in which the heat sink 12 includes two constituent units so as to have a step portion on the side surface. Such a substrate for a light-emitting element is not limited to a case where the heat sink has two constituent units. The number of constituent elements of the heat sink 12 may be three or more. In other words, in the substrate for a light-emitting element of the embodiment, the cross section of the heat sink 12 may have a stepped shape of three or more stages. In this case, the second coating layer 14 may be disposed between at least one constituent unit between two or more constituent units. In this case, the first constituent unit can be arbitrarily determined from a plurality of constituent units other than the second constituent unit closest to the first main surface 11a side. In the case of the substrate for a light-emitting element of the embodiment, when the cross-section of the heat sink 12 has a stepped shape of three or more stages, it is preferable that the second cladding layer 14 is disposed in two or more constituent units other than the second constituent unit. All constitute a unit.

Next, an embodiment of a light-emitting device will be described.

Fig. 7 is a plan view showing a first embodiment of the light-emitting device. 8 is a cross-sectional view of the light-emitting device shown in FIG. 7 as viewed in the direction of the arrow BB.

The light-emitting device 20 has the light-emitting element substrate 10 of the first embodiment. The light-emitting element 21 is mounted on the first cladding layer 13 on the substrate 10 for a light-emitting element. The light-emitting element 21 is a one-wire type light-emitting element having electrodes on both main faces. One of the electrodes of the light-emitting element 21 is electrically connected to the wiring conductor 15 by a bonding wire 22. The other electrode of the light-emitting element 21 is electrically connected to the first cladding layer 13. Further, in this case, the heat sink 12 functions as a conductive portion in addition to the function as a heat radiating portion.

Inside the casing 16, a sealing layer 23 is provided to cover the light-emitting element 21 and the like. As a constituent material of the sealing layer 23, a sealing material such as an fluorenone resin or an epoxy resin which is generally used for a sealing material for a light-emitting device can be used without particular limitation.

Next, a second embodiment of the substrate for a light-emitting element will be described.

FIG. 9 is a plan view showing a substrate for a light-emitting element of a second embodiment. Moreover, FIG. 10 is a cross-sectional view of the substrate for a light-emitting element shown in FIG. 9 as viewed in the direction of arrows CC. In the substrate for a light-emitting element of the first embodiment, the heat-dissipating body 12 has a stepped portion on the side surface, and the heat-emitting element 12 has an inclined portion on the side surface of the substrate for a light-emitting element according to the second embodiment. This aspect is different. Other than this, it is the same as the substrate for a light-emitting element of the first embodiment. In the light-emitting element substrate of the second embodiment, the heat sink 12 different from the light-emitting element substrate of the first embodiment will be mainly described.

For example, as shown in FIG. 10, in the substrate for a light-emitting element of the second embodiment, the heat sink 12 has an inclined portion on the side surface. The heat radiating body 12 includes a plurality of constituent units divided by a plane perpendicular to the thickness direction. For example, the heat radiating body 12 has the first constituent unit 121 and the second constituent unit 122 in this order from the second main surface 11b side.

Further, the heat sink 12 may be divided into three or more constituent units. In this case, the first constituent unit can be plural from the second constituent unit closest to the first main surface 11a side. The constituent units are arbitrarily determined. In the case of the light-emitting element substrate of the embodiment, when the cross-section of the heat sink 12 is three or more, it is preferable that the second cladding layer 14 is disposed between the constituent units of the two or more constituent units other than the second constituent unit. .

The second coating layer 14 is disposed between the first constituent unit 121 and the second constituent unit 122. Moreover, the second coating layer 14 covers the end surface on the first main surface 11a side of the first constituent unit 121 disposed on the second main surface 11b side. Further, the outer edge of the second covering layer 14 is disposed on the outer side of the outer edge formed on the end surface of the first main surface 11a of the first constituent unit 121.

In this case, the first covering layer 13 is disposed so as to cover the end surface of the second main surface 11a on the first main surface 11a side, and the outer edge is the same as the first embodiment of the light-emitting element substrate. Located on the outer side of the distance L ₁ that is specific to the outer edge of the end face. Further, the second covering layer 14 is also disposed so as to cover the end surface on the first main surface 11a side of the first constituent unit 121, and the outer edge is located outside the specific distance L ₂ shown by the outer edge of the end surface. Moreover, it is preferable that the area of the end surface on the first main surface 11a side of the second structural unit 122 is smaller than the area of the mounting portion of the light-emitting element. Further, it is preferable that the area of the end surface on the first main surface 11a side of the first constituent unit 121 is larger than the area of the mounting portion of the light-emitting element.

Further, in the case of the heat sink 12 having the inclined portion on the side surface, the angle θ of the side surface of the heat sink 12 measured in the same manner as described above is preferably 20 or more. When the heat sink 12 has an inclined portion on the side surface, the angle θ is an angle formed by the first straight line extending in the thickness direction of the base 11 and the second straight line passing through the side surface of the heat sink 12 .

Next, a method of manufacturing a substrate for a light-emitting element will be described below by taking a case where the substrate is a low-temperature co-fired ceramic (LTCC). Further, the method for producing the substrate for a light-emitting element of the present invention is not limited thereto.

The substrate for a light-emitting element can be produced, for example, by the following steps (A) to (D).

(A) A green sheet containing a glass powder and a ceramic powder is used to produce a green sheet (hereinafter referred to as a sheet forming step).

(B) forming a conductor layer such as the heat sink 12, the first covering layer 13, and the second covering layer 14 The unfired conductor layer (hereinafter referred to as a conductor layer forming step).

(C) A green sheet layer on which an unfired conductor layer is formed (hereinafter referred to as a laminate step).

(D) A green sheet in which the laminate is fired (hereinafter, referred to as a baking step).

Hereinafter, each step will be described.

(A) Sheet making step

A paste is prepared by adding a binder, adding a plasticizer, a dispersant, a solvent, or the like to the glass ceramic composition containing the glass powder and the ceramic powder. The slurry is formed into a sheet shape by a doctor blade method or the like, and dried to produce a green sheet. In this case, the green sheets are preferably manufactured in plural numbers, for example, according to the number of constituent units of the heat sink 12 (two or more in the case of the present invention). Further, the green sheet corresponding to each constituent unit may be a single layer structure composed of one sheet, or may be a laminate structure composed of two or more sheets.

The glass powder preferably has a glass transition point (Tg) of 550 ° C or more and 700 ° C or less. When the glass transition point (Tg) is less than 550 ° C, there is a tendency to become degreased. When the temperature exceeds 700 ° C, the shrinkage initiation temperature becomes high and the dimensional accuracy is lowered.

The glass powder is preferably precipitated crystals when calcined at 800 ° C or more and 930 ° C or less. In the case of precipitation of crystallization, sufficient mechanical strength can be obtained. Further, the glass powder preferably has a crystallization peak temperature (Tc) of 880 ° C or less as measured by DTA (differential thermal analysis). When the crystallization peak temperature (Tc) is 880 ° C or less, the dimensional accuracy becomes high.

As such a glass powder, for example, it is preferable to contain SiO _{2 of} 57 mol% or more and 65 mol% or less, B ₂ O _{3 of} 13 mol% or more and 18 mol% or less, CaO of 9 mol% or more and 23 mol% or less, and Al ₂ O _{3 3} mol% or more. 8 mol% or less and at least one selected from the group consisting of K ₂ O and Na ₂ O is 0.5 mol% or more and 6 mol% or less in total. In the case of such a glass powder, the flatness of the surface of the substrate 11 is improved.

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

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

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

CaO is added in order to improve the stability of glass or the precipitation of crystals, and to lower the glass melting temperature or the glass transition point (Tg). When the content of CaO is less than 9 mol%, there is a possibility that the glass melting temperature is excessively high. On the other hand, when the content of CaO exceeds 23 mol%, the glass becomes unstable. The content of CaO is preferably 12 mol% or more, more preferably 13 mol% or more, and particularly preferably 14 mol% or more. Further, the content of CaO is preferably 22 mol% or less, more preferably 21 mol% or less, still more preferably 20 mol% or less.

K ₂ O, Na ₂ O lowers the glass transition point (Tg). When the total content of K ₂ O and Na ₂ O is less than 0.5 mol%, there is a possibility that the glass melting temperature or the glass transition point (Tg) is excessively high. On the other hand, when the total content of K ₂ O and Na ₂ O exceeds 6 mol%, the chemical durability, particularly the acid resistance, is lowered, and the electrical insulating properties are also lowered. The total content of K ₂ O and Na ₂ O is preferably 0.8 mol% or more and 5 mol% or less.

In addition, the glass powder is not necessarily limited to those composed only of the above components, and other components may be contained within a range satisfying various characteristics such as a glass transition point (Tg). In the case of containing other components, the total content thereof is preferably 10 mol% or less.

The glass powder is obtained by a method of producing a glass having the above glass composition by a melt method, and pulverizing it by a dry pulverization method or a wet pulverization method. In the case of the wet pulverization method, it is preferred to use water as a solvent. For the pulverization, for example, a pulverizer such as a roll mill, a ball mill, or a jet mill can be used.

The 50% average particle diameter (D ₅₀ ) of the glass powder is preferably 0.5 μm or more and 2 μm or less. When the 50% average particle diameter of the glass powder is 0.5 μm or more, the glass powder is less likely to aggregate, is easy to handle, and is uniformly dispersed. On the other hand, when the 50% average particle diameter of the glass powder is 2 μm or less, the increase in the glass softening temperature or insufficient sintering is suppressed. The adjustment of the particle size is carried out by classification or the like. Further, in the present specification, the particle diameter means a value obtained by a particle diameter measuring device according to a laser diffraction-scattering method.

As the ceramic powder, a manufacturer for glass ceramics from the past can be used. As the ceramic powder, for example, an alumina powder, a zirconia powder, or a mixture of an alumina powder and a zirconia powder can be preferably used. The 50% average particle diameter (D ₅₀ ) of the ceramic powder is, for example, preferably 0.5 μm or more and 4 μm or less.

The glass powder is blended and mixed with the ceramic powder to obtain a glass ceramic composition. The ratio of the glass powder to the ceramic powder is preferably 30% by mass or more and 50% by mass or less, and the ceramic powder is 50% by mass or more and 70% by mass or less. A paste is prepared by adding a binder, adding a plasticizer, a dispersant, a solvent, or the like to the glass ceramic composition.

Examples of the binder include polyvinyl butyral, an acrylic resin, and the like. Examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, and butyl benzyl phthalate. Further, examples of the solvent include organic solvents such as toluene, xylene, 2-propanol and 2-butanol.

The slurry is formed into a sheet shape by a doctor blade method or the like, and dried to obtain a green sheet. The green film can also be composed of a plurality of layers. The green sheet is produced, for example, into three types of the first base 111, the second base 112, and the casing 16.

(B) Conductor layer forming step

On the green sheet to be the first substrate 111, after the hole portion is formed, the hole portion is filled with the conductor paste by a screen printing method to form an unfired conductor layer which is the first constituent unit 121 of the heat sink 12. Further, a conductor paste is printed on the front and back sides of the green sheet by a screen printing method to form an unfired conductor layer which serves as the second cladding layer 14 and the external electrodes 17 and 18.

On the green sheet to be the second substrate 112, after the hole portion is formed, the hole portion is filled with the conductor paste by a screen printing method to form an unfired conductor layer which is the second constituent unit 122 or the like. Further, a conductor paste is printed on the front side of the green sheet by a screen printing method to form an unfired conductor layer which becomes the first cladding layer 13 and the wiring conductor 15.

The green sheet that becomes the casing 16 forms a hole portion that surrounds the first cladding layer 13 and the wiring conductor 15.

For the conductive paste, for example, a metal powder such as copper, silver or gold may be added to a metal powder such as ethyl cellulose, and a solvent or the like may be added as needed to form a paste.

(C) Lamination step

Each of the green sheets on which the unfired conductor layer is formed is laminated in a specific order, and then these are pressure-bonded and integrated.

(D) baking step

The integrated green sheets are subjected to baking for sintering the glass ceramic composition. Thereby, the substrate 10 for a light-emitting element is obtained. Further, it is also possible to perform degreasing for removing the binder or the like before the baking, as needed.

The degreasing temperature is preferably 500 ° C or more and 600 ° C or less. The degreasing time is preferably from 1 hour to 10 hours. When the degreasing temperature is 500 ° C or more and the degreasing time is 1 hour or more, the removal of the binder or the like is good. Degreasing temperature is below 600 ° C, off When the grease time is 10 hours or less, productivity and the like become good.

The calcination temperature is preferably 800 ° C or more and 930 ° C or less, more preferably 850 ° C or more and 900 ° C or less, and still more preferably 860 ° C or more and 880 ° C or less in consideration of densification and productivity. The baking time is preferably 20 minutes or more and 60 minutes or less. When the baking temperature is 800 ° C or more, densification becomes good. When the baking temperature is 930 ° C or lower, the deformation is suppressed and the productivity is improved. Further, in the case of using a conductor paste containing silver, if the baking temperature is 880 ° C or lower, the deformation due to softening is suppressed.

[Examples]

Hereinafter, embodiments of the invention will be described.

Furthermore, the invention is not limited to the embodiments.

[Examples 1 to 19]

As shown in Table 1, the ratio (V ₂ /V ₁ ), the thickness of the base 11 , the cross-sectional area of the second constituent unit 122 (the area corresponding to the end surface on the first main surface 11 a side), and the distances L ₁ and L _{2 are} changed. A substrate for evaluation having a structure as shown in FIGS. 1 to 3 was prepared for the radius of curvature. Here, the ratio (V ₂ /V ₁ ) is a ratio of the volume (V ₂ ) of the heat sink 12 to the total volume (V ₁ ) of the base 11 and the members disposed therein. The distance L ₁ is the distance between the sides of the outer edge (the square) formed by the end faces on the first main surface 11 a side of the second constituent unit 122 and the sides of the outer edge of the first covering layer 13 (the square), and the distance L ₂ is the distance between each side (square) of the outer edge formed by the end surface on the first main surface 11a side of the first constituent unit 121 and each side (square) of the outer edge of the second cladding layer 14. The radius of curvature is the radius of curvature of the corner of the square of the heat sink 12 perpendicular to the thickness direction. Further, the cross-sectional shape of the first constituent unit 121 is the same in the thickness direction, and the cross-sectional shape of the second constituent unit 122 is also the same in the thickness direction, and the quadrangular prism is formed three-dimensionally.

As described above, the planar shape of the base 11, the heat sink 12, the first covering layer 13, and the second covering layer 14 is square. The length of one side of the base 11 is 3 mm, and the length of one side of the first constituent unit 121 in the heat radiating body 12 is 1.28 mm, so that the area value of Table 1 is made. The length of one side of the second constituent unit 122 in the heat radiating body 12 changes. Further, the length of one side of the inner side of the casing 16 is 1.8 mm. The first base 111 and the second base 112 have the same thickness. Further, the thickness of the first covering layer 13 was 12 μm, and the thickness of the second covering layer 14 was 12 μm.

Further, the substrate for evaluation was produced as follows.

The raw materials are blended and mixed such that SiO _{2 is} 60.4 mol%, B ₂ O _{3 is} 15.6 mol%, Al ₂ O _{3 is} 6 mol%, CaO is 15 mol%, K ₂ O is 1 mol%, and Na ₂ O is 2 mol%. The raw material mixture was poured into a platinum crucible, and after melting at 1600 ° C for 60 minutes, the molten glass was allowed to flow out and cooled. The glass was pulverized by an alumina ball mill for 40 hours to produce a glass powder. Further, the solvent used in the pulverization was ethanol.

The glass ceramic composition was prepared by blending and mixing the glass powder to 40% by mass, and alumina powder (manufactured by Showa Denko Co., Ltd., trade name: AL-45H) to be 60% by mass. Into 50 g of the glass ceramic composition, an organic solvent (mixed with toluene, xylene, 2-propanol, 2-butanol at a mass ratio of 4:2:2:1) of 15 g, a plasticizer (adjacent) was prepared. 2.5 g of di-2-ethylhexyl phthalate), 5 g of polyvinyl butyral (manufactured by DENKA Co., Ltd., trade name: PVK #3000K) as a binder, and further prepared with a dispersant (manufactured by BYK-Chemie Co., Ltd.) Trade name: BYK180), mixed to prepare a slurry.

The slurry is applied onto a PET (polyethylene terephthalate) film by a doctor blade method and dried to produce a green sheet which becomes the first substrate 111, the second substrate 112, and the casing 16. . The thickness of the base 11, the first base 111, and the second base 112 is adjusted by the thickness of the green sheet.

For each green sheet, the formation of the hole portion, the filling of the conductor paste, printing, and the like are performed, and the unfired conductor layer such as the heat sink 12, the first covering layer 13, and the second covering layer 14 is formed. The ratio (V ₂ /V ₁ ), the cross-sectional area of the second constituent unit 122 in the heat radiating body 12, and the radius of curvature of the corner portion of the cross-sectional shape (square shape) are determined by the size and shape of the hole portion formed in the green sheet. Adjustment. Moreover, the adjustment of the distances L ₁ and L ₂ is adjusted by the printing range of the conductor paste.

Further, the conductor paste is produced by blending a conductive powder (manufactured by Daikin Chemical Co., Ltd., trade name: S550) and ethyl cellulose as a vehicle at a mass ratio of 85:15 to form a solid shape. After the content of the component was 85% by mass, it was dispersed in α-terpineol as a solvent, and then kneaded in a ceramic mortar for 1 hour, and further dispersed three times by a three-roll kneader. Further, the filling and printing of the conductor paste are performed by screen printing.

The green sheets on which the unfired conductor layers are formed are laminated in a specific order, and then pressure-bonded and integrated. Thereafter, the integrated green sheets were degreased at a degreasing temperature of 550 ° C and a degreasing time of 5 hours. Further, calcination was carried out at a calcination temperature of 870 ° C and a calcination time of 30 minutes. Thereby, a substrate for evaluation was produced.

[Comparative Example 1]

A substrate for evaluation was produced in the same manner as in Example 1 except that the first coating layer 13 was not formed.

[Comparative Example 2]

A substrate for evaluation was produced in the same manner as in Example 1 except that the second coating layer 14 was not formed.

Next, the substrate for evaluation of the examples and the comparative examples was bonded to the first cladding layer 13 by heating with a gold tin eutectic solder at 310 ° C for 60 seconds, and then using an optical microscope. The rupture of the surface was observed at a magnification of 30 times. The results are shown in Table 1. Further, in Comparative Example 1, the light-emitting element was directly bonded to the heat sink 12 under the above conditions using a gold-tin eutectic solder, and evaluated. In Table 1, "○" indicates that no crack occurred on the surface of the evaluation substrate, and "x" indicates that some crack occurred on the surface of the evaluation substrate.

As is clear from Table 1, the evaluation substrate of Comparative Example 1 having no first coating layer 13 and the evaluation substrate of Comparative Example 2 having no second coating layer 14 were all broken. On the other hand, none of the evaluation substrates having the first coating layer 13 and the second coating layer 14 was cracked.

Claims (12)

A substrate for a light-emitting element, comprising: a plate-shaped substrate having a first main surface on which the light-emitting element is mounted; and a second main surface disposed on the opposite side of the first main surface; and a heat sink disposed on the substrate In the inside, the area of the end surface on the second main surface side is larger than the area of the end surface on the first main surface side, and has a plurality of constituent units divided in the thickness direction of the base body; and the first coating layer is disposed in the above The main surface of the first main surface of the second heat dissipating body disposed on the first main surface side of the first main surface is disposed on the first main surface side, and the outer edge is disposed on the first main surface side of the second constituent unit The second coating layer is disposed between the plurality of constituent elements of the heat dissipating body, and the second coating layer is disposed between the plurality of constituent units, and the second constituent layer is disposed above the second constituent unit The end surface on the first main surface side of the first constituent unit on the main surface side, and the outer edge is disposed on the outer side of the outer edge of the first main surface side of the first constituent unit, and the heat radiating body and the heat radiating body First coating layer and second coating The cross-section perpendicular to the thickness direction each having a square cross-sectional shape, the vertical member of the heat sink to the radius of curvature of the corner portion of the square cross section of the thickness direction of not less than 0.03mm and 0.40mm or less. A substrate for a light-emitting element, comprising: a plate-shaped substrate having a first main surface on which the light-emitting element is mounted; and a second main surface disposed on the opposite side of the first main surface; and a heat sink disposed on the substrate The inside end surface of the second main surface side has an area larger than an area of the end surface of the first main surface side, and has a plurality of constituent units divided in a thickness direction of the base body; The first coating layer is disposed on the first main surface, and covers an end surface of the second main component of the heat dissipating body disposed on the first main surface side on the first main surface side, and an outer edge is disposed on the first surface a second coating layer disposed between the plurality of constituent elements of the heat dissipating body and covering the constituent elements The second constituent unit is formed on an end surface on the first main surface side of the first constituent unit on the second main surface side, and an outer edge is formed on an end surface of the first main surface on the first main surface side. On the outer side of the outer edge, the ratio of the volume of the heat sink to the total volume of the substrate and the member disposed therein is 10% by volume or more and 30% by volume or less. A substrate for a light-emitting element, comprising: a plate-shaped substrate having a first main surface on which the light-emitting element is mounted; and a second main surface disposed on the opposite side of the first main surface; and a heat sink disposed on the substrate In the inside, the area of the end surface on the second main surface side is larger than the area of the end surface on the first main surface side, and has a plurality of constituent units divided in the thickness direction of the base body; and the first coating layer is disposed in the above The main surface of the first main surface of the second heat dissipating body disposed on the first main surface side of the first main surface is disposed on the first main surface side, and the outer edge is disposed on the first main surface side of the second constituent unit The second coating layer is disposed between the plurality of constituent elements of the heat dissipating body, and the second coating layer is disposed between the plurality of constituent units, and the second constituent layer is disposed above the second constituent unit The end surface on the first main surface side of the first constituent unit on the main surface side, and the outer edge is disposed on the outer side of the outer edge of the first main surface side of the first constituent unit, and the first coating layer The outer edge and the above-mentioned first main surface are mounted on A light emitting element mounting portion of the same outside edge or located further inside than the outside edge of the mounting portion. The substrate for a light-emitting element according to any one of claims 1 to 3, wherein the heat dissipating body has a stepped portion on a side surface of the second main surface side, and a cross-sectional area is gradually increased. The substrate for a light-emitting device according to any one of claims 1 to 3, wherein each of the outer edge of the end surface on the first main surface side of the second constituent unit and the first cladding corresponding to each of the sides The distance between each side of the outer edge of the layer is 0.03 mm or more. The substrate for a light-emitting device according to any one of claims 1 to 3, wherein each of the outer edge of the end surface on the first main surface side of the first constituent unit and the second coating corresponding to each of the sides The distance between each side of the outer edge of the layer is 0.05 mm or more. The substrate for a light-emitting element according to any one of claims 1 to 3, wherein the substrate has a thickness of 0.20 mm or more and 0.60 mm or less. The substrate for a light-emitting element according to any one of claims 1 to 3, wherein the thickness of the first coating layer is 5 μm or more and 20 μm or less. The substrate for a light-emitting device according to any one of claims 1 to 3, wherein the thickness of the second coating layer is 5 μm or more and 20 μm or less. The substrate for a light-emitting element according to any one of claims 1 to 3, wherein the first coating layer and the second coating layer comprise a metal material. The substrate for a light-emitting device according to any one of the first to third aspect, wherein the outer edge of the second main surface of the second constituent unit is not mounted on the outer surface of the first main surface. The outer edges of the parts overlap and are located on the inner side. A light-emitting device comprising: the substrate for a light-emitting element according to any one of claims 1 to 11, and a light-emitting device mounted on the substrate for the light-emitting device.