JP6492443B2 - Light emitting element substrate and light emitting device - Google Patents

Description

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

  2. Description of the Related Art In recent years, light emitting devices using LED elements have been used for backlights of mobile phones and large liquid crystal TVs as light emitting diode (LED) elements become brighter and whiter. About such a light-emitting device, the emitted-heat amount is increasing by the high brightness | luminance of an LED element, and sufficient light-emitting luminance is not necessarily acquired for the temperature rise by this.

  Therefore, in order to suppress the temperature rise of the light emitting element, a heat radiating body is provided so as to penetrate through the base constituting the light emitting element substrate. About the light emitting element substrate provided with such a heat radiator, heat dissipation improves as the ratio of the volume of the heat radiator to the volume of the base increases, and the temperature rise of the light emitting element is suppressed.

  However, when the ratio of the volume of the heat radiating body to the volume of the base becomes large, when the substrate for a light emitting element is manufactured by firing, the base around the heat radiating body is easily cracked due to the difference in thermal expansion between the base and the heat radiating body . In order to suppress such cracking of the substrate, for example, the boundary between the substrate and the radiator is covered with a coating layer made of a metal material (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 2006-41230

  In recent years, the ratio of the volume of the heat radiating body to the volume of the base has been increased in order to increase the heat dissipation of the light emitting element substrate, and the temperature condition has been increased to increase the productivity when mounting the light emitting element on the light emitting element substrate. However, when the light emitting element is mounted, the substrate around the heat radiating body is easily broken. Such cracking of the substrate when mounting the light emitting element is considered to be caused by corrosion of the substrate during plating. That is, the light emitting element substrate is plated in order to improve solder wettability when the light emitting element is mounted. Plating is performed by immersing the light emitting element substrate in a plating solution. Since the plating solution is acidic, the substrate corrodes when the light emitting element substrate is immersed.

  When the light emitting element is mounted on the light emitting element substrate, the light emitting element substrate is heated to a high temperature in order to melt the solder for joining them. At this time, if the substrate is corroded, the substrate is likely to be cracked based on the corroded portion around the heat sink due to the difference in thermal expansion between the substrate and the heat sink. In particular, when temperature conditions are severe in order to increase productivity when mounting a light-emitting element on a light-emitting element substrate, the base body is likely to be cracked starting from a corroded portion around the radiator.

  The present invention has been made to solve the above-described problems, and provides a substrate for a light-emitting element in which corrosion of the base body due to plating is suppressed, and thereby cracking of the base body when mounting the light-emitting element is suppressed. It is aimed. Another object of the present invention is to provide a light emitting device having such a light emitting element substrate.

The light emitting element substrate of the present invention includes a base, a heat radiator, a coating layer, and a glass layer . Release Netsutai, the end on at least one major surface of the substrate is provided in the interior of substrate so as to penetrate. The coating layer covers the entire end face of the heat radiating body and the inner peripheral portion of the glass layer. The glass layer is provided on the main surface side so as to cover the boundary between the base and the heat radiator. The thermal expansion coefficient of the glass layer is smaller than the thermal expansion coefficient of the substrate.

The light emitting device of the present invention includes a substrate for light-emitting element and a light-emitting element mounted on the substrate for light-emitting element. The light emitting element substrate includes a base, a heat radiator, a coating layer, and a glass layer . Release Netsutai, the end on at least one major surface of the substrate is provided in the interior of substrate so as to penetrate. The coating layer covers the entire end face of the heat radiating body and the inner peripheral portion of the glass layer. The glass layer is provided on the main surface side so as to cover the boundary between the base and the heat radiator. The thermal expansion coefficient of the glass layer is smaller than the thermal expansion coefficient of the substrate. The light emitting element is mounted on the coating layer at a position overlapping the coating layer, and has approximately the same size as the coating layer. The outer edge of the radiator is located inside the outer edge of the light emitting element.

  According to the present invention, since the glass layer covering the boundary between the substrate and the heat radiating body is provided, corrosion of the substrate during plating is suppressed, and thereby cracking of the substrate when the light emitting element is mounted is suppressed.

The top view which shows the board | substrate for light emitting elements of 1st Embodiment. The bottom view of the board | substrate for light emitting elements shown in FIG. FIG. 2 is a cross-sectional view of the light emitting element substrate shown in FIG. Explanatory drawing explaining angle (theta) of the side surface of a heat radiator. The top view which shows the positional relationship of a heat radiator, a glass layer, and a 1st coating layer. The top view which shows the positional relationship of a heat radiator and a 2nd coating layer. The top view which shows 1st Embodiment of a light-emitting device. BB arrow sectional drawing of the light-emitting device shown in FIG. The top view which shows the board | substrate for light emitting elements of 2nd Embodiment. CC sectional view taken on the CC line of the light emitting element use substrate shown in FIG.

Hereinafter, embodiments of the light emitting element substrate will be described.
FIG. 1 is a top view showing a first embodiment of a light emitting element substrate. FIG. 2 is a bottom view of the light-emitting element substrate shown in FIG. FIG. 3 is a cross-sectional view of the light emitting element substrate shown in FIG.

  For example, as shown in FIG. 3, the light emitting element substrate 10 includes a plate-like substrate 11. The base 11 has a first main surface 11a on which the light emitting element is mounted, and a second main surface 11b disposed on the opposite side of the first main surface 11a. A heat radiator 12 is provided inside the base 11.

  On the first main surface 11a side, a glass layer 13 is provided so as to cover the boundary between the base 11 and the radiator 12. Moreover, the 1st coating layer 14 is provided in the 1st main surface 11a side so that the whole end surface of the thermal radiation body 12 and the inner peripheral part of the glass layer 13 may be covered. Furthermore, a wiring conductor 15 (FIG. 1) is provided on the first main surface 11 a side, and a frame body 16 is provided so as to surround the first coating layer 14 and the wiring conductor 15.

  On the other hand, external electrodes 17 and 18 are provided on the second main surface 11b side. Further, a through conductor (not shown) that connects the wiring conductor 15 and the external electrode 17 is provided inside the base body 11. Further, a second covering layer 19 is provided in the middle of the heat radiating body 12.

  The base body 11 has, for example, a square planar shape, and includes a first base body 111 and a second base body 112 in order from the second main surface 11b side.

  The thickness of the base | substrate 11 is 0.2 mm or more and 0.6 mm or less normally. The thickness of each of the first base 111 and the second base 112 is usually 0.1 mm or more. When the thickness of each substrate is 0.1 mm or more, handling of the green sheet used for manufacturing each substrate becomes good. Further, when the thickness of each substrate is 0.1 mm or more, the heat radiating body 12 can be easily formed on the green sheet. The thickness of each substrate is more preferably 0.15 mm or more.

  On the other hand, the thickness of each substrate is preferably 0.30 mm or less, and more preferably 0.25 mm or less. Further, when the base 11 is composed of the first base 111 and the second base 112, the ratio of the thickness of the first base 111 to the thickness of the second base 112 is from 3: 7 to 7: 3. Is preferable, and the range of 4: 6 to 6: 4 is more preferable, and 5: 5 (that is, the same thickness) is particularly preferable.

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

  Among these, glass ceramics are preferable because the firing temperature is low. For example, a silver reflective film may be formed on the first main surface 11a side of the light emitting element substrate 10 in order to increase the light reflectance. In the case of glass ceramics, since the firing temperature is low, it is preferable because the silver reflective film can be fired simultaneously. Glass ceramics are preferable because they have better processability than aluminum oxide.

  The radiator 12 is provided so as to extend in the thickness direction of the base 11. Such a radiator 12 has, for example, a square cross-sectional shape. Here, the thickness direction means a direction perpendicular to the first main surface 11a and the second main surface 11b. The cross-sectional shape means a cross-sectional shape perpendicular to the thickness direction.

  It is preferable that the outer edge of the end surface of the heat dissipating body 12 on the first main surface 11a side is located inside the outer edge of the light emitting element. It is preferable that the outer edge of the radiator 12 is located on the inner side of the outer edge of the light emitting element because light utilization efficiency is improved.

  That is, the first covering layer 14 formed so as to cover the end face of the heat radiating body 12 is usually formed in a slightly wider range than the heat radiating body 12 in order to suppress cracking of the base 11. A nickel (Ni) plating layer and a gold (Au) plating layer are sequentially formed on the surface of the first coating layer 14 in order to improve the wettability of solder when mounting a semiconductor element. / Au plating layer or the like is formed.

  However, such a plated layer easily absorbs light from the semiconductor element, and when the outer edge of the heat radiating body 12 is located outside the outer edge of the light emitting element, the outer edge of the plated layer is naturally more than the outer edge of the light emitting element. Is positioned on the outer side, and light from the semiconductor element is easily absorbed.

  When the outer edge of the heat dissipating body 12 is located on the inner side of the outer edge of the light emitting element, the outer edge of the first coating layer 14 can be located on the inner side of the outer edge of the light emitting element. Also, the outer edge of the plating layer is positioned on the inner side, so that absorption of light from the semiconductor element can be suppressed.

  FIG. 4 is an explanatory diagram for explaining the angle θ of the side surface of the radiator 12. In the case of the radiator 12 having the stepped portion on the side surface, the angle θ is defined by the first straight line 31 extending in the thickness direction of the base 11, the surface and the side surface on the second main surface 11 b side in each of the structural units 121 and 122. The angle formed by the second straight line 32 passing through the corner portion formed by the boundary.

  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 the heat dissipation is improved. The angle θ is more preferably 30 ° or more from the viewpoint of heat dissipation. As for the angle θ, about 70 ° is sufficient from the viewpoint of heat dissipation, and 60 ° or less is preferable. The angle θ is particularly preferably about 45 °.

  The constituent material of the radiator 12 is preferably a metal material having high thermal conductivity. Examples of such a metal material include those containing copper, silver, gold, or the like as a main component. Specifically, a metal composed of silver, silver and platinum, or silver and palladium is preferable. Note that 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. When the constituent material of the substrate 11 is other than glass ceramics, the constituent material of the radiator 12 is preferably a refractory metal such as tungsten or molybdenum because deformation during firing is suppressed.

  The glass layer 13 is provided, for example, so as to cover the boundary between the base 11 and the radiator 12 on the first main surface 11a side and the second main surface 11b side. Usually, the glass layer 13 is provided so as to go around the boundary that exists in an annular shape around the radiator 12. By providing the glass layer 13 so as to cover the boundary, the contact of the plating solution to the substrate 11 near the boundary is suppressed, and thereby the corrosion of the substrate 11 near the boundary is suppressed. As a result, cracking of the substrate 11 in the vicinity of the boundary when the light emitting element is mounted is suppressed.

  The glass layer 13 is preferably provided so as to cover not only the boundary but also the substrate 11 near the boundary. Since the glass layer 13 is provided so as to cover the substrate 11 in the vicinity of the boundary, the corrosion of the substrate 11 is suppressed in a wide range, so that the generation of cracks is further suppressed.

  In general, since the thermal conductivity of the glass layer 13 is lower than the thermal conductivity of the radiator 12, if the glass layer 13 is provided so as to cover the end face of the radiator 12, the heat dissipation performance decreases. For this reason, it is preferable that the glass layer 13 is provided so as not to cover the end face of the radiator 12.

  Moreover, the glass layer 13 should just be provided in the at least one main surface side chosen from the 1st main surface 11a side and the 2nd main surface 11b side, However, It provides at least the 1st main surface 11a side. It is preferable that

  That is, on the first main surface 11a side, the outer edge of the semiconductor element and the outer edge of the first covering layer 14 are usually located at the same position, or the outer edge of the first covering layer 14 is more than the outer edge of the semiconductor element. A first covering layer 14 is provided so as to be located on the inner side, and the first covering layer 14 does not cover a wide area of the base 11, and the base 11 near the boundary is easily cracked due to corrosion. Yes. On the other hand, on the second main surface 11b side, since the wide range of the base 11 is covered by the external electrode 18, cracks due to corrosion of the base 11 near the boundary are easily suppressed. For this reason, it is preferable that the glass layer 13 is provided at least on the first main surface 11a side.

The distance from the boundary to the outer edge of the glass layer 13 (L ₁ , FIGS. 3 and 5) is preferably 50 μm or more. A distance (L ₁ ) of 50 μm or more is preferable because a wide range of the substrate 11 is covered with the glass layer 13. The distance (L ₁ ) is more preferably 100 μm or more, and further preferably 150 μm or more.

Here, the distance (L ₁ ) is, for example, the first main surface 11a side and the second main surface 11b side because the area of the end surface of the radiator 12 is different between the first main surface 11a side and the second main surface 11b side. In the case where the position of the boundary is different from the main surface 11b side, it is preferable to use the boundary on each main surface side as a reference.

For example, the distance (L ₁ ) on the first main surface 11a side is the distance from the boundary between the second base 112 and the second structural unit 122 to the outer edge of the glass layer 13 on the first main surface 11a side. And The distance (L ₁ ) on the second main surface 11b side is the distance from the boundary between the first base 111 and the first structural unit 121 to the outer edge of the glass layer 13 on the second main surface 11b side. And

For example, the glass layer 13 may be provided so as to cover the entire first main surface 11 a of the base 11. However, if the glass layer 13 is provided so as to cover the entire first main surface 11 a of the base 11, the light emitting element substrate 10 is likely to be warped due to a difference in thermal expansion between the base 11 and the glass layer 13. Become. From the viewpoint of suppressing the occurrence of such warpage, the distance (L ₁ ) is preferably 800 μm or less, more preferably 600 μm or less, and even more preferably 500 μm or less.

Note that the distance (L ₁ ) is the distance between the boundary and each side of the glass layer 13 when both the boundary between the base 11 and the radiator 12 and the glass layer 13 have a rectangular planar shape. Further, when one of the boundary and the glass layer 13 has a planar shape other than a quadrangular shape, the shortest distance between the boundary and the outer edge of the glass layer 13 is defined as a distance (L ₁ ).

  The glass layer 13 preferably has a thickness of 5 μm or more and 50 μm or less. When the thickness of the glass layer 13 is 5 μm or more, it is preferable because the glass layer 13 is formed evenly over the entire boundary between the base 11 and the radiator 12. The thickness of the glass layer 13 is more preferably 7 μm or more, and further preferably 10 μm or more. On the other hand, when the thickness of the glass layer 13 is 50 μm or less, the warp of the light emitting element substrate 10 due to the difference in thermal expansion between the base 11 and the glass layer 13 is suppressed, and the formation of the glass layer 13 is facilitated. The thickness of the glass layer 13 is more preferably 40 μm or less, further preferably 30 μm or less, and particularly preferably 20 μm or less.

  The constituent material of the glass layer 13 only needs to contain a glass material, but it is preferable that the glass layer 13 contains borosilicate glass because it is not easily corroded by the plating solution and can effectively protect the substrate 11 from the plating solution.

As the borosilicate glass, for example, the content of SiO ₂ is 62% or more and 84% or less, the content of B ₂ O ₃ is 10% or more and 25% or less, and Al ₂ O ₃ is expressed in mol% based on oxide. The content is 0% to 5%, the total content of Na ₂ O and K ₂ O is 0% to 5%, the total content of SiO ₂ and Al ₂ O ₃ is 62% to 84%, A borosilicate glass having a MgO content of 0% to 10% and a total content of CaO, SrO, and BaO of 5% or less is preferable.

  In addition, borosilicate glass is not necessarily limited to what consists only of the said component, Other components can be contained in the range which has a predetermined effect. When other components are contained, the total content is preferably 10% or less.

  The glass layer 13 can contain various ceramic powders for the purpose of improving the reflectance. Examples of the ceramic powder include aluminum oxide, titanium oxide, zirconium oxide, silicon oxide, cerium oxide, and zinc oxide.

  The thermal expansion coefficient of the glass layer 13 is preferably smaller than the thermal expansion coefficient of the substrate 11. If the thermal expansion coefficient of the glass layer 13 is smaller than the thermal expansion coefficient of the substrate 11, a compressive stress is generated in the glass layer 13, so that it is difficult to break when heat or impact is applied.

  The first coating layer 14 is provided in order to suppress cracking of the substrate 11, and is provided in order to further suppress cracking of the substrate 11 when used in combination with the glass layer 13. The first covering layer 14 is disposed on the first main surface 11 a side of the base body 11. The first covering layer 14 has, for example, a square planar shape, and the outer edge is disposed outside the boundary between the base 11 and the radiator 12 so as to cover the entire end surface of the radiator 12. And disposed so as to cover the inner periphery of the glass layer 13. As described above, the first coating layer 14 is disposed so as to straddle the radiator 12 and the glass layer 13, that is, straddle the boundary between the base 11 and the radiator 12, so that only the glass layer 13 is present. The crack of the base 11 is suppressed more than when it is provided.

The distance from the boundary to the outer edge of the first coating layer 14 (L ₂ , FIGS. 3 and 5) is preferably 30 μm or more. When the distance (L ₂ ) is 30 μm or more, cracking of the substrate 11 is effectively suppressed. The distance (L ₂ ) is more preferably 50 μm or more.

On the other hand, when the distance (L ₂ ) is increased, the outer edge of the first covering layer 14 may be located outside the outer edge of the light emitting element when the light emitting element is mounted. May be absorbed. The distance (L ₂ ) is preferably 300 μm or less, and more preferably 250 μm or less.

Note that the distance (L ₂ ) is between the boundary and each side of the first coating layer 14 when both the boundary between the base 11 and the radiator 12 and the first coating layer 14 have a rectangular planar shape. Distance. When one of the boundary and the first coating layer 14 has a planar shape other than a quadrangular shape, the shortest distance between the boundary and the outer edge of the first coating layer 14 is defined as a distance (L ₂ ).

Here, as for the relationship between the first coating layer 14 and the glass layer 13, it is preferable that the outer edge of the glass layer 13 is located outside the outer edge of the first coating layer 14. That is, the first coating layer 14 cannot be provided in a wide range from the viewpoint of light absorption when the plating layer is provided, but the glass layer 13 does not have such a problem and thus has a wide range. Can be provided. Therefore, by covering a wider area than the first coating layer 14 with the glass layer 13, cracking due to corrosion of the substrate 11 around the first coating layer 14 can also be suppressed. The first coating layer 14 and the glass layer 13, the distance _{(L 1)} and the distance _{(L 2)} the difference between _(L 1 -L ₂₎ is preferably provided so as to be above 50 [mu] m, 100 [mu] m or more and More preferably, it is provided.

  The thickness of the first coating layer 14 is preferably 5 μm or more, and more preferably 10 μm or more, from the viewpoint of suppressing cracking of the substrate 11. Further, the thickness of the first coating layer 14 is preferably 20 μm or less, and more preferably 15 μm or less, from the viewpoint of suppressing warpage of the substrate 11 due to a difference in thermal expansion.

  The constituent material of the first coating layer 14 is preferably a metal material because it has a high effect of suppressing cracking of the substrate 11 and has high thermal conductivity. Examples of such a metal material include metals having copper, silver, gold and the like as main components. Specifically, a metal composed of silver, silver and platinum, or silver and palladium is preferable.

  The second coating layer 19 is provided to suppress cracking of the substrate 11, and is provided to further suppress cracking of the substrate 11 when used in combination with the glass layer 13 and the first coating layer 14. Yes. The second coating layer 19 has, for example, a square cross-sectional shape, and is disposed between the first structural unit 121 and the second structural unit 122. The second covering layer 19 covers the entire end surface of the first structural unit 121 and is arranged so that the outer edge is outside the boundary between the first base 111 and the first structural unit 121. ing. As described above, the second coating layer 19 is disposed so as to straddle the first base 111 and the first structural unit 121, whereby the base 11 is cracked so as to progress to the first main surface 11a. Is suppressed.

The distance (L ₃ , FIG. 3, FIG. 6) from the boundary between the first base 111 and the first structural unit 121 to the outer edge of the second coating layer 19 is preferably 0.05 mm or more. When the distance (L ₃ ) is 0.05 mm or more, cracking of the substrate 11 is effectively suppressed. The distance (L ₃ ) is more preferably 0.10 mm or more.

On the other hand, when the distance (L ₃ ) is increased, the first base 111 and the second base 112 are easily separated. In light of suppressing such peeling, the distance (L ₃ ) is preferably equal to or less than 0.35 mm, and more preferably equal to or less than 0.30 mm.

Note that the distance (L ₃ ) is equal to the boundary and the second coating layer when the boundary between the first base 111 and the second structural unit 121 and the second coating layer 19 both have a rectangular planar shape. The distance between 19 sides. When one of the boundary and the second coating layer 19 has a planar shape other than a quadrangular shape, the shortest distance between the boundary and the outer edge of the second coating layer 19 is defined as a distance (L ₃ ).

  The thickness of the second coating layer 19 is preferably 5 μm or more, and more preferably 10 μm or more. In addition, the thickness of the second coating layer 19 is preferably 20 μm or less, and more preferably 15 μm or less, from the viewpoint of suppressing warpage of the substrate 11 due to a difference in thermal expansion.

  In addition, when the heat radiator 12 has three or more structural units, the second coating layer 19 may be provided in one of the plurality of structural units, or the second coating layer 19 may be provided between all the structural units. May be provided. Moreover, the range in which each 2nd coating layer 19 is provided is defined on the basis of the structural unit arrange | positioned in contact with each 2nd main surface 11b side.

  Examples of the constituent material of the second coating layer 19 include a metal material, a resin material, and the like, and a metal material is preferable because it has a high effect of suppressing cracking of the base 11 and has high thermal conductivity. Examples of such a metal material include metals having copper, silver, gold and the like as main components. Specifically, a metal composed of silver, silver and platinum, or silver and palladium is preferable.

  Further, the shape of the frame 16, the wiring conductor 15, the external electrodes 17 and 18, and the through conductor (not shown) are not limited, and the shape and the like can be selected as necessary.

  As described above, the step having the step portion on the side surface of the heat radiating body 12 has been described, but such a configuration is not limited to one having two structural units. The structural unit of the radiator 12 may be three or more. In this case, the second coating layer 19 may be disposed between at least one structural unit between two or more structural units, but the second coating layer 19 is disposed between all the structural units of two or more structural units. Is preferably arranged.

Next, an embodiment of a light emitting device will be described.
FIG. 7 is a top view showing the first embodiment of the light emitting device. FIG. 8 is a cross-sectional view of the light emitting device shown in FIG.

  The light emitting device 20 includes the light emitting element substrate 10 of the first embodiment. The light emitting element 21 is mounted on the first coating layer 14 in the light emitting element substrate 10. The light emitting element 21 is a 1-wire type light emitting element, and has electrodes on both main surfaces. One electrode 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 coating layer 14. The radiator 12 has a function as a conductive part in addition to a function as a heat radiating part.

  A sealing layer 23 is provided inside the frame 16 so as to cover the light emitting element 21 and the like. As a constituent material of the sealing layer 23, a sealing material such as a silicone resin or an epoxy resin generally used for a sealing material of a light emitting device is used without any particular limitation.

Next, a second embodiment of the light emitting element substrate will be described.
FIG. 9 is a top view showing the light emitting element substrate of the second embodiment. FIG. 10 is a cross-sectional view taken along the line CC of the light emitting element substrate shown in FIG.

  The radiator 12 is not limited to the one having the step portion on the side surface, and may have the inclined portion on the side surface. Thus, what has an inclination part in a side surface also has what has a some structural unit in the thickness direction, for example, the 1st structural unit 121 and 2nd in order from the 2nd main surface 11b side. And those having the structural unit 122. In the second embodiment, the glass layer 13, the first coating layer 14, the second coating layer 19 and the like are provided in the same manner as in the first embodiment.

  Further, the angle θ of the side surface of the radiator 12 is preferably 20 ° or more. Here, the angle θ is an angle formed between 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 radiator 12 when the heat radiator 12 has an inclined portion on the side surface. is there.

Next, the manufacturing method of the light emitting element use substrate is demonstrated.
In the following description, the substrate 11 is made of glass ceramics as an example.

The light emitting element substrate 10 is manufactured through the following steps (A) to (E).
(A) A green sheet is produced using a glass ceramic composition containing glass powder and a ceramic filler (hereinafter referred to as a sheet production process).
(B) An unsintered layer to be the heat radiator 12 and the glass layer 13 is formed on the green sheet (hereinafter referred to as an unsintered layer forming step).
(C) A green sheet on which an unfired layer is formed is stacked (hereinafter referred to as a stacking step).
(D) The laminated green sheets are fired (hereinafter referred to as a firing step).

(A) Sheet preparation process A slurry is prepared by adding a binder and, if necessary, a plasticizer, a dispersant, a solvent, etc. to a glass ceramic composition containing glass powder and ceramic powder. This slurry is formed into a sheet by a doctor blade method or the like and dried to produce a green sheet. At this time, it is preferable to manufacture a plurality of types of green sheets in accordance with the number of structural units of the radiator 12, for example. Each type of green sheet may have a single-layer structure composed of one sheet, or may have a laminated structure composed of two or more sheets.

  The glass powder preferably has a glass transition point (Tg) of 550 ° C. or higher and 700 ° C. or lower. When the glass transition point (Tg) is less than 550 ° C., degreasing may be difficult. When it exceeds 700 degreeC, there exists a possibility that shrinkage start temperature may become high and a dimensional accuracy may fall.

  It is preferable that crystals are precipitated when the glass powder is fired at 800 ° C. or higher and 930 ° C. or lower. When crystals are precipitated, sufficient mechanical strength is obtained. Further, the glass powder preferably has a crystallization peak temperature (Tc) measured by DTA (differential thermal analysis) of 880 ° C. or lower. When the crystallization peak temperature (Tc) is 880 ° C. or lower, the dimensional accuracy is increased.

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

  As ceramic powder, what is conventionally used for manufacture of glass ceramics can be used. As the ceramic powder, for example, aluminum oxide powder, zirconia powder, or a mixture of aluminum oxide powder and zirconia powder can be suitably used.

  A glass ceramic composition can be obtained by blending and mixing glass powder and ceramic powder. The ratio of the glass powder to the ceramic powder is preferably 30% by mass to 50% by mass for the glass powder and 50% by mass to 70% by mass for the ceramic powder. A slurry is prepared by adding a binder and, if necessary, a plasticizer, a dispersant, a solvent, and the like to the glass ceramic composition.

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

  The slurry is formed into a sheet by a doctor blade method or the like and dried to obtain a green sheet. The green sheet may be a laminate of a plurality of sheets. For example, three types of green sheets are used as the first base 111, the second base 112, and the frame 16.

(B) Unfired layer forming step After forming a hole in the green sheet to be the first substrate 111, the hole is filled with a conductive paste by a screen printing method, and the first structural unit 121 is formed by baking. An unsintered heat dissipation layer is formed. Further, a glass paste is printed on the surface of the green sheet by a screen printing method, and an unfired glass layer that becomes the glass layer 13 is formed by firing. Furthermore, a conductor paste is printed by a screen printing method, and an unfired conductor layer that becomes the second coating layer 19 and the external electrodes 17 and 18 is formed by firing. After forming a hole in the green sheet to be the second substrate 112, the hole is filled with a conductive paste by a screen printing method, and an unsintered heat dissipation layer that becomes the second structural unit 122 is formed by firing. Form.

  Further, a glass paste is printed on the surface of the green sheet by a screen printing method, and an unfired glass layer that becomes the glass layer 13 is formed by firing. Furthermore, a conductor paste is printed by a screen printing method, and an unfired conductor layer that becomes the first coating layer 14 and the wiring conductor 15 is formed by firing.

  A hole having a size that surrounds the first covering layer 14 and the wiring conductor 15 is formed in the green sheet to be the frame body 16.

  As the conductive paste, for example, a paste obtained by adding a vehicle such as ethyl cellulose to a metal powder containing copper, silver, gold or the like as a main component, and a solvent as necessary can be used. As the glass paste, for example, a paste obtained by adding a vehicle such as ethyl cellulose to a glass powder such as borosilicate glass and, if necessary, a ceramic powder, a solvent or the like can be used.

(D) Lamination process After each green sheet in which the unfired layer is formed is laminated in a predetermined order, these are pressed and integrated.

(E) Firing step Firing for sintering the glass ceramic composition is performed on the integrated green sheet. Thereby, the board | substrate 10 for light emitting elements is obtained. In addition, you may perform the degreasing for removing a binder etc. before baking as needed.

  The degreasing temperature is preferably 500 ° C. or higher and 600 ° C. or lower. The degreasing time is preferably 1 hour or more and 10 hours or less. When the degreasing temperature is 500 ° C. or higher and the degreasing time is 1 hour or longer, the removal of the binder and the like is good. When the degreasing temperature is 600 ° C. or less and the degreasing time is 10 hours or less, productivity and the like are good.

  The baking temperature is preferably 800 ° C. or higher and 930 ° C. or lower, more preferably 850 ° C. or higher and 900 ° C. or lower, and further preferably 860 ° C. or higher and 880 ° C. or lower in consideration of densification and productivity. The firing time is preferably from 20 minutes to 60 minutes. When the firing temperature is 800 ° C. or higher, densification is good. When the firing temperature is 930 ° C. or lower, deformation is suppressed and productivity is improved. Moreover, when the conductor paste containing silver is used, the deformation | transformation by softening is suppressed as a calcination temperature is 880 degrees C or less.

  In the above manufacturing method, the method of forming the green glass layer by printing the glass paste has been described. However, the method of forming the green glass layer is not necessarily limited to the method of printing the glass paste. For example, a green sheet serving as an unfired glass layer is manufactured using glass powder such as borosilicate glass having a similar glass composition, and this is laminated on the green sheet serving as the first substrate 111 or the second substrate 112. Thus, an unfired glass layer may be formed.

  In such a light emitting element substrate 10, for example, a plating layer is formed on the surface of the first coating layer 14 for the purpose of increasing the wettability of solder for joining the light emitting elements 21. Examples of the plating layer include a Ni / Au plating layer in which a nickel (Ni) plating layer and a gold (Au) plating layer are formed in this order from the first coating layer 14 side.

  The formation of the plating layer is performed by immersing the light emitting element substrate 10 in a plating solution. At this time, if the glass layer 13 is provided so as to cover the substrate 11, corrosion of the substrate 11 due to contact with the plating solution is suppressed, and as a result, cracking when the light emitting element 21 is mounted is suppressed.

  In plating, it is preferable to employ plating conditions that suppress cracking of the substrate 11 when the light emitting element 21 is mounted. For example, if the current density at the time of plating is high, the substrate 11 is likely to break, and therefore it is preferable to reduce the current density at the time of plating. Furthermore, it is preferable to shorten the plating time because the substrate 11 is easily broken when the plating time is increased.

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

[Examples 1 to 12]
As shown in Table 1, the distance (L ₁ ) from the boundary between the base 11 and the radiator 12 on the first main surface 11a side to the outer edge of the glass layer 13 and the thickness of the glass layer 13 were changed, and FIG. An evaluation substrate having a structure as shown in FIG. Incidentally, with the exception of the first distance of the main surface 11a side of the glass layer 13 (L ₁₎ and the thickness, the evaluation substrate in each example, the structure was the same.

Details of the evaluation substrate are as follows. The outer shape of the evaluation substrate is 3 mm × 3 mm, the outer shape of the first structural unit 121 of the radiator 12 is 1.2 mm × 1.2 mm, the outer shape of the second structural unit 122 is 0.8 mm × 0.8 mm, the first The thickness of the base 111 (same for the first structural unit 121) and the second base 112 (same for the second structural unit 122) are each 0.15 mm, and the thickness of the frame 16 is 0.4 mm. . The outer shape of the first coating layer 14 is 1.0 mm × 1.0 mm, the thickness is 0.015 mm, and the distance (L ₂ ) is 100 μm. The outer shape of the second covering layer 19 is 1.4 mm × 1.4 mm, the thickness is 0.015 mm, and the distance (L ₃ ) is 100 μm.

Moreover, the evaluation substrate was manufactured as follows.
In terms of mol% based on oxide, SiO ₂ is 60.4%, B ₂ O ₃ is 15.6%, Al ₂ O ₃ is 6%, CaO is 15%, K ₂ O is 1%, Na ₂ O. The raw materials were blended and mixed so as to be 2%. The raw material mixture was put in a platinum crucible and melted at 1600 ° C. for 60 minutes, and then the molten glass was poured out and cooled. This glass was pulverized with an aluminum oxide ball mill for 40 hours to produce a glass powder. In addition, ethyl alcohol was used as a solvent for pulverization.

  A glass ceramic composition was produced by blending and mixing the glass powder to 40% by mass and aluminum oxide powder (manufactured by Showa Denko KK, trade name: AL-45H) to 60% by mass. 50 g of this glass ceramic composition, 15 g of an organic solvent (toluene, xylene, 2-propanol, 2-butanol mixed at a mass ratio of 4: 2: 2: 1), plasticizer (di-2-ethylhexyl phthalate) 2.5 g of polyvinyl butyral (trade name: PVK # 3000K, manufactured by Denka) as a binder and 5 g of a dispersant (trade name: BYK180, manufactured by Big Chemie) were further blended and mixed to prepare a slurry.

  This slurry was applied onto a PET film by a doctor blade method and dried to produce green sheets to be the first substrate 111, the second substrate 112, and the frame 16. The thicknesses of the substrate 11, the first substrate 111, and the second substrate 112 were adjusted by the thickness of the green sheet.

In each green sheet, a hole is formed as necessary, and the radiator 12, the glass layer 13, the first coating layer 14, and the second coating layer 19 are filled or printed with a conductor paste or glass paste. An unfired layer was formed. The adjustment distance (L ₁₎ and the thickness of the glass layer 13 was adjusted by the print range and a print thickness at this time.

  The conductor paste is silver powder (manufactured by Daiken Chemical Industry Co., Ltd., trade name: S550), ethyl cellulose as a vehicle is blended at a mass ratio of 85:15, and the solid content is 85% by mass as a solvent. And then kneaded for 1 hour in a porcelain mortar, and further dispersed three times with a three-roll mill. The conductor paste was filled and printed by screen printing.

  The glass paste is prepared by blending glass powder and ethyl cellulose as a vehicle in a mass ratio of 85:15 and dispersing in α-terpineol as a solvent so that the solid content is 85% by mass, and then in a porcelain mortar. The mixture was kneaded for a period of time and further dispersed three times with three rolls. The glass paste was printed by screen printing.

The glass powder used for the glass paste is borosilicate containing 81.6% of SiO ₂ , 16.6% of B ₂ O _{3 and} 1.8% of K ₂ O in terms of mol% based on oxide. Made of acid glass.

  The green sheets on which the unfired layer was formed were laminated in a predetermined order, and then pressed and integrated. Thereafter, the integrated green sheet was degreased at a degreasing temperature of 550 ° C. and a degreasing time of 5 hours. Furthermore, baking was performed at a degreasing temperature of 870 ° C. and a degreasing time of 30 minutes. This produced the board | substrate for evaluation.

[Comparative Example 1]
An evaluation substrate was produced in the same manner as in Example 1 except that the glass layer 13 and the first coating layer 14 were not provided.

  Next, plating was performed on the evaluation substrates of Examples and Comparative Examples to form a plating layer. In addition, about the evaluation board | substrate of the Example, the plating layer was formed in the surface of the 1st coating layer 14, and the plating layer was formed in the surface of the heat radiator 12 about the evaluation board | substrate of a comparative example. Plating was performed by immersing the evaluation substrate in the order of nickel plating solution and gold plating solution. The thickness of the nickel plating layer is 10 μm, and the thickness of the gold plating layer is 0.3 μm. A nickel sulfamate aqueous solution was used as the nickel plating solution, and a potassium gold cyanide aqueous solution was used as the gold plating solution.

  Then, about the board | substrate for evaluation of an Example and a comparative example, the light emitting element 21 whose external shape is 1 mm x 1 mm was heated at 310 degreeC for 60 second using the gold-tin eutectic solder on the plating layer, and was joined. After joining, the surface of the evaluation substrate was observed for cracking at a magnification of 30 using an optical microscope. Table 1 shows the ratio (crack generation rate) at which some cracks occurred on the surface of the evaluation substrate. Table 1 shows the presence or absence of warping before forming the plating layer for the evaluation substrates of the examples and comparative examples.

  As is clear from Table 1, it can be seen that the evaluation substrate of the comparative example that does not have the glass layer 13 and the first coating layer 14 has a high incidence of cracking when the light emitting element 21 is bonded. On the other hand, it can be seen that the evaluation substrate of the example having the glass layer 13 and the first covering layer 14 has a low incidence of cracking when the light emitting element 21 is bonded. Moreover, when the formation range and thickness of the glass layer 13 are in a fixed range, it turns out that especially the incidence rate of a crack becomes low and generation | occurrence | production of curvature is also suppressed.

  DESCRIPTION OF SYMBOLS 10 ... Board | substrate for light emitting elements, 11 ... Base | substrate, 12 ... Radiator, 13 ... Glass layer, 14 ... 1st coating layer, 15 ... Wiring conductor, 16 ... Frame, 17, 18 ... External electrode, 19 ... 2nd 20 ... light emitting device, 21 ... light emitting element, 22 ... bonding wire, 31 ... first straight line, 32 ... second straight line, 111 ... first base, 112 ... second base, 121 ... first 1 structural unit, 122... Second structural unit 122.

Claims (5)

Provided on the main surface side so as to cover a base, a heat dissipating body provided in the base so that an end thereof penetrates at least one main surface of the base, and a boundary between the base and the heat dissipating body A substrate for a light emitting device having a glass layer,
For a light emitting device, comprising a coating layer that covers the entire end face of the radiator and an inner peripheral portion of the glass layer, wherein the thermal expansion coefficient of the glass layer is smaller than the thermal expansion coefficient of the substrate. substrate. The light emitting element substrate according to claim 1 , wherein an outer edge of the glass layer is located 150 μm or more outside from an outer edge of the heat radiator. The light emitting element substrate according to claim 1 , wherein the glass layer has a thickness of 5 μm or more and 50 μm or less. The glass layer is expressed in mol% based on oxide, and the content of SiO ₂ is 62% or more and 84% or less, the content of B ₂ O ₃ is 10% or more and 25% or less, and the content of Al ₂ O ₃ is 0% to 5%, the total content of Na ₂ O and K ₂ O is 0% to 5%, the total content of SiO ₂ and Al ₂ O ₃ is 62% to 84%, MgO content 4. The substrate for a light emitting device according to claim 1, comprising a borosilicate glass having an amount of 0% to 10% and a total content of CaO, SrO, and BaO of 5% or less. A substrate for a light emitting device according to claim 1 ;
A light emitting device having a light emitting element mounted on the light emitting element substrate ,
The light emitting element is mounted on the coating layer at a position overlapping with the coating layer, and is substantially the same size as the coating layer,
A light emitting device in which an outer edge of the heat dissipating body is located inside an outer edge of the light emitting element.

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