JP6210211B2 - Method for manufacturing light emitting device - Google Patents

Description

  The present invention relates to bonding of a light emitting element using an intermetallic compound and a substrate.

  Conventionally, with respect to a method of joining a light emitting element to a substrate or the like by soldering, the first metal and the second metal used for joining are laminated on the back surface (mounting surface) of the light emitting element, and the substrate is joined by heating and melting There is something to do.

In the manufacture of such a light emitting device, a metal layer (for example, a bonding layer, a reflective layer, a diffusion prevention layer, etc.) necessary for bonding is deposited on the back surface of the light emitting device in a wafer state where the light emitting device is not separated. Or by sputtering.

  In such a wafer, there is usually a portion (NG portion) that cannot be used as a light emitting element of a product. Conventionally, a plurality of metal layers are also formed in such an NG portion. The wafer is subjected to the process of separating the light emitting elements and the inspection process, and the NG portion is discarded. For this reason, there has been a problem that the material discarded along with the disposal of the NG part is used excessively.

  The present invention is to solve such problems and to provide a cheaper method for manufacturing a light emitting device.

  Therefore, the method for manufacturing a light emitting device according to the present invention includes a step of preparing a light emitting element in which a first metal is formed on a mounting surface, a step of preparing a substrate on which a second metal is formed, and the first method. A metal and the second metal are brought into contact, and heated and melted at a temperature higher than at least one of the melting points of the first and second metals, thereby forming an intermetallic compound and bonding the substrate and the light emitting element. Steps.

  According to the present invention, since it is not necessary to form the second metal on the back side of the light emitting element, the light emitting device can be manufactured at low cost.

Schematic sectional view of a light emitting device according to an embodiment of the present invention. 1 is a schematic plan view and a schematic cross-sectional view for explaining a light emitting device according to an embodiment of the present invention. Schematic sectional drawing which shows the manufacturing process of the light-emitting device concerning one Embodiment of this invention.

The method for manufacturing a light emitting device of the present invention includes at least a light emitting element, a substrate, and first and second metals.
In the present invention, the first metal provided on the light emitting element side and the second metal provided on the substrate side are heated and melted to form a bonding material (bonding layer) of the intermetallic compound, whereby the light emitting element and the substrate are obtained. Bonding is performed.

  In the method of manufacturing the light emitting device of the present invention, since the metal as the bonding material is provided on each of the light emitting element side and the substrate side, it is not necessary to provide the second metal on the light emitting element side. The use of materials can be reduced, and a light-emitting device can be manufactured at low cost.

  FIG. 1 shows an example of the configuration of the light emitting element of this embodiment. Thus, the structure in which the reflective layer, the diffusion preventing layer, and the first metal are sequentially provided in order from the mounting surface of the light emitting element is preferable.

1st metal 4
The first metal 4 is formed having a first metal element that forms an intermetallic compound (eutectic, solder, etc.) and forms the bonding material 20 by being melted with a second metal 11 described later. The material is not particularly limited, and Cu, Pt, Fe, Au, or the like can be used. The first metal 4 is preferably higher than the melting point of the second metal. The reason is that the light-emitting element 1 can be stably bonded by first forming the bonding material 20 by heating and melting the second metal 11 and sequentially melting the second metal 11 into the first metal 4.

  The amount or thickness of the first metal 4 (when the first metal 4 is formed in a layer) is as much as possible so that the first metal element remains as a single substance without forming an intermetallic compound with the second metal element. In order to reduce the amount, the same amount as the second metal 11 is desirable.

  Further, when the first metal 4 is formed in a wafer state, the first metal 4 provided in the NG portion is discarded as described above, so that the first metal 4 is made of a material cheaper than the second metal 11. Preferably there is. Thereby, a light emitting device can be manufactured at low cost.

  The first metal 4 can be formed by a known method such as sputtering or vapor deposition. The first metal 4 is preferably formed in a layer shape. Thereby, the light emitting element 1 can be stably mounted.

Reflective layer 2
A reflective layer 2 may be provided between the light emitting element 1 and the first metal 4. The reflective layer 2 is provided on the mounting surface side of the light emitting element 1 and at a position closer to the light emitting element 1 than the bonding material 20 or the first metal 4, and plays a role of improving light extraction efficiency. As a material, a material such as Al or Ag having high reflectivity is desirable, and the thickness can be, for example, about 1000 to 2000 mm.

Diffusion prevention layer 3
In the present invention, the diffusion preventing layer 3 may be provided on the mounting surface side of the light emitting element 1 and between the reflective layer 2 and the bonding material 20 or the first metal 4. Thereby, it is possible to prevent the metal of the bonding material 20 from diffusing into the reflective layer 2 and reducing the light reflectance of the reflective layer 2. The thickness of the diffusion preventing layer 3 is preferably a thickness that does not affect the light extraction efficiency (for example, about 1000 to 2000 mm). As a material, a material such as Au or Ni is preferably used.

Light emitting element 1
As the light emitting element 1, a semiconductor light emitting element having an arbitrary wavelength can be selected. For example, as blue and green light emitting elements, nitride semiconductors such as InGaN, GaN, and AlGaN, and those using GaP as a semiconductor layer can be used. As the red light emitting element, GaAlAs, AlInGaP, or the like can be used. Furthermore, a light-emitting element made of a material other than this can also be used. The composition, emission color, size, number, and the like of the light emitting element to be used can be appropriately selected according to the purpose.
The light emitting element 1 may have an insulating substrate or a conductive substrate. Further, it may be formed only of a semiconductor layer without having a substrate. When the light emitting element 1 has a substrate, the first metal 4 is preferably formed on the substrate side.

  In the case of a light-emitting device having a wavelength conversion member, a nitride semiconductor capable of emitting a short wavelength that can efficiently excite the wavelength conversion member is preferably used. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal. Moreover, it can be set as the light emitting element 1 which outputs not only the light of a visible light range but an ultraviolet-ray and infrared rays.

  The light emitting element 1 is preferably mounted on a light reflecting material 31 of the substrate 13 as shown in FIG. Thereby, the light extraction efficiency of the light emitting device can be improved.

  The light emitting element 1 usually has positive and negative electrodes electrically connected to a conductive member such as a pair of positive and negative leads 31 (also serving as a metal part 12 and a light reflecting material in FIG. 2) provided in the light emitting device. ing. These positive and negative electrodes may be provided on one side, or may be provided on both the upper and lower surfaces (that is, the upper surface and the mounting surface) of the light emitting element 1. The connection method with the conductive member is not particularly limited, and may be connected by a wire 40 described later or may be connected by flip chip mounting.

  In order to supply power to the light emitting element, the bonding material 20 formed of the first metal 4 and the second metal 11 can be made conductive and bonded to the electrode of the light emitting element 1, or a wire 40 can be used. The wire 40 can also be connected so as to connect the plurality of light emitting elements 1. Moreover, as shown in FIG. 2, it can also provide so that the lead | read | reed 31 may be connected for every light emitting element 1. FIG.

  The material of the wire 40 is preferably Au, Al, Cu or the like, but may be Ag or Ag alloy having a high light reflectance.

Substrate 13
FIG. 3 shows an example of the configuration of the substrate 13. As shown in FIG. 3, the substrate 13 has a metal part 12, and the second metal 11 is provided on the metal part 12.
The substrate 13 is a member that supports the light emitting element 1, and the light emitting element 1 is bonded to the substrate 13 via a bonding material 20.

Examples of the material of the substrate 13 include those having the resin molded body 36.
As the base material of the resin molded body, a thermosetting resin or a thermoplastic resin can be used, and it is particularly preferable to use a thermosetting resin. The thermosetting resin is preferably a resin having low gas permeability compared to the resin used for the sealing member, and specifically, a modified epoxy resin such as an epoxy resin composition, a silicone resin composition, or a silicone-modified epoxy resin. Examples thereof include a composition, a modified silicone resin composition such as an epoxy-modified silicone resin, a polyimide resin composition, a modified polyimide resin composition, a urethane resin, and a modified urethane resin composition. Fine particles such as TiO ₂ , SiO ₂ , Al ₂ O ₃ , MgO, MgCO ₃ , CaCO ₃ , Mg (OH) ₂ , Ca (OH) ₂ as a filler (filler) on the base material of such a resin molded body It is preferable to adjust the light transmittance by mixing the light and the like so as to reflect about 60% or more of the light from the light emitting element, more preferably about 90%.

  The material used for the substrate 13 is not limited to the resin as described above, and may be formed of an inorganic material such as ceramic, glass, or metal. Accordingly, a highly reliable light-emitting device with little deterioration and the like can be obtained. In particular, by using a low temperature sintered ceramic (LTCC), a light emitting device having both high light extraction efficiency and high reliability can be manufactured.

  The substrate 13 includes at least the metal part 12. A second metal 11 is provided on the metal portion 12.

Second metal 11
The second metal 11 is a second metal element which is formed on the substrate 13 and forms an intermetallic compound by being heated and melted with the first metal 4. The material is not particularly limited as long as it forms the first metal 4 and an intermetallic compound (or eutectic, solder). However, since heat treatment is performed at a low temperature, a comparison between Sn, In, Bi, and the like is possible. A metal with a low melting point is preferred. Accordingly, the bonding material 20 can be efficiently formed by heating and melting the second metal element and sequentially dissolving the second metal element into the first metal element.

  In addition, a material having a melting point lower than that of the first metal 4 is preferable. Thereby, the joining material 20 can be efficiently formed by first heat-melting the second metal element and sequentially dissolving the second metal element into the first metal element. In particular, when a plurality of the second metals 11 are provided separately, the second metal 11 first melts, so that the second metal 11 spreads over and substantially contacts the entire surface of the first metal 4. Thereby, while reducing the quantity of the 2nd metal 11, the part which the 2nd metal 11 melts can be enlarged, and the joining material 20 can be formed thinly and uniformly.

  The step of providing the second metal 11 on the substrate 13 may be any method, but for example, it is preferable to apply the second metal 11 onto the substrate in a separated state by a dispenser, printing, or the like. Thus, by adjusting the usage amount of the second metal 11, a light emitting device can be manufactured at low cost.

  Specifically, depending on the nature of the metal used, for example, when the size of the light-emitting element 1 is a rectangle of 800 × 800 μm in plan view, the second metal 11 has a hemispherical shape with a diameter of about 100 μm. , And can be separated into equal numbers of about 3 × 3 to 4 × 4 at regular intervals. However, the second metal 11 may be provided on substantially the entire surface of the portion to be mounted on the substrate 13 by sputtering or the like.

  The second metal 11 is preferably fixed to the substrate 13 by heating or pressurization after the second metal 11 is formed on the substrate 13 and before the light emitting element 1 is placed. Thereby, it is possible to prevent the second metal 11 from falling off the substrate 13. In particular, when the second metal 11 is formed by being separated into a plurality of pieces, it is possible to prevent the second metal 11 from falling off, which is preferable. Further, it is preferable to flatten the upper surface of the second metal 11 during heating and pressurization. Thereby, the light emitting element 1 can be stably disposed on the upper surface of the second metal 11.

  The shape of the second metal 11 may be any shape, and may be a layered shape in addition to the hemispherical shape as described above. By making it layered, the light emitting element 1 can be stably placed and contacted. Further, the shape in plan view is not particularly limited, and may be the same shape as the first metal 4 or may be different. Alternatively, the shape may be substantially the same as that of the light emitting element 1. Thereby, the light emitting element 1 can be stably mounted.

  Further, an anti-oxidation layer for reducing oxidation of the second metal 11 is provided as a thin film (for example, about 150 mm thick) between the substrate 13 (more specifically, the metal portion 12) and the second metal 11. It is preferable that This antioxidant layer may be dissolved in the bonding material 20 when the second metal 11 is melted in the heat treatment. Au or the like can be used as a material for such an antioxidant layer.

  Then, the first metal 4 provided on the light emitting element 1 side as described above and the second metal 11 provided on the substrate 13 are heated and melted. Thereby, the intermetallic compound of the 1st metal 4 and the 2nd metal 11 is formed, and the light emitting element 1 and the board | substrate 13 are joined.

  Specifically, this step is performed by placing the light emitting element 1 on the second metal 11 provided on the substrate 13 so that the first metal 4 is in contact with the first metal 4 and heating and melting it. Such a heating and melting method is not particularly limited, and can be performed using a known reflow apparatus or the like.

  The heating temperature varies depending on the materials used as the first metal 4 and the second metal 11 and is not particularly limited, but is preferably lower than the melting point of the first metal 4 and higher than the melting point of the second metal 11. . Thereby, the second metal 11 can be gradually dissolved in the first metal 4. However, in consideration of the heat resistance of the light emitting element 1 and the substrate 13, the heating temperature needs to be lower than that. Therefore, for example, when Cu is used for the first metal 4, Sn is used for the second metal 11, and the light emitting element 1 has a GaN-based semiconductor layer, the temperature may be in the range of 260 ° C. to 335 ° C. preferable.

  Similarly, the heating time varies depending on the materials used as the first metal 4 and the second metal 11. For example, when Cu is used for the first metal 4 and Sn is used for the second metal 11, it is preferably about 100 to 200 s in the heating temperature range.

Sealing member 39
The light emitting device 30 of the present invention may further include a sealing member 39. By providing the sealing member so as to cover the light emitting element, the substrate, the wire, and the like, the covered member can be protected from dust, moisture, and external force, and the reliability of the light emitting device can be improved. .

  The sealing member 39 may be provided in any shape. For example, when the concave portion is formed in the substrate (resin molded body 36) as shown in FIG. 2, it may be provided so as to fill the concave portion, or may be provided in a substantially hemispherical lens shape or the like. .

  The sealing member 39 preferably has a light-transmitting property capable of transmitting light from the light-emitting element 1 and has a light resistance that is not easily deteriorated by them. As specific materials, a silicone resin composition, a modified silicone resin composition, a modified epoxy resin composition, a fluororesin composition, and the like, such as an insulating resin composition having translucency that can transmit light from the light-emitting element 1 are used. Can be mentioned. In particular, a hybrid resin including at least one resin having a siloxane skeleton as a base, such as dimethyl silicone, phenyl silicone having a low phenyl content, or a fluorine-based silicone resin can also be used.

  The method for forming the sealing member 39 is not particularly limited. When the sealing member 39 is a resin, a potting (dropping) method, a compression molding method, a printing method, a transfer molding method, a jet dispensing method, spray coating, or the like can be used. In the case of the substrate 13 having recesses as shown in FIG. 2, the potting method is preferable, and when the flat substrate 13 is used, the compression molding method and the transfer molding method are preferable.

  The shape of the outer surface of the sealing member 39 is not particularly limited, and various shapes can be selected according to the light distribution characteristics required for the light emitting device 30. For example, directivity and light extraction efficiency can be adjusted by making the upper surface into a convex lens shape, a concave lens shape, a Fresnel lens shape, a rough surface, and the like.

  The sealing member 39 may contain a colorant, a light diffusing agent, a light reflecting material, various fillers, a wavelength conversion member, and the like.

  The wavelength conversion member is a material that converts the wavelength of light from the light emitting element 1. When the light emitted from the light emitting element 1 is blue light, the wavelength converting member is preferably an yttrium / aluminum / garnet phosphor (hereinafter referred to as “YAG: Ce”), which is a kind of aluminum oxide phosphor. Used for. The YAG: Ce phosphor absorbs part of the blue light from the light emitting element and emits yellow light that is a complementary color depending on the content of the YAG: Ce phosphor. Therefore, a high output light emitting device that emits white mixed light is used. It can be formed relatively easily. Moreover, fluorescent substances that emit red light such as CASN, SCASN, and KSF can also be used.

Protective element The light emitting device 30 may include various members in addition to the above. For example, a Zener diode can be mounted as the protection element 41.

FIG. 3 shows an embodiment of the present invention.
As shown in FIG. 3A, first, as a first step, the second metal 11 is provided on the metal portion 12 provided on the substrate 13. Specifically, Sn as the second metal 11 is heated and dissolved, and a plurality of Sn is arranged on the substrate 13 in a substantially hemispherical shape by a dispenser or the like.

Next, as shown in FIG. 3B, as a second step, the arranged second metal 11 is fixed to the substrate 13. Specifically, the arranged second metal 11 is heat-pressed (hot pressed) by the hot plate 14 and fixed to the substrate. The temperature of this hot press is such that the second metal 11 is not completely melted but deformed, and is preferably a temperature lower than the melting point of the second metal 11. For example, when Sn is used as the second metal 11, it is preferably performed at about 180 to 200 ° C.
Thereafter, in order to temporarily fix the light emitting element 1 on the second metal 11, a temporary fixing agent (flux or the like) is applied.

  Next, as shown in FIGS. 3C and 3D, as a third step, a light-emitting element 1 similar to the light-emitting element 1 described in the embodiment is prepared, and the first metal 4 is the second step. It is placed on the second metal 11 so as to be in contact with the metal 11. The first metal 4 is Cu, and is formed in a layer form on substantially the entire mounting surface side of the light emitting element 1. A reflective layer 2 and a diffusion prevention layer 3 are formed in this order between the light emitting element 1 and the first metal 4. The light emitting element 1 is mounted in accordance with the position of the second metal 11 disposed on the substrate 13 with the side on which the first metal 4 is formed facing down.

  As a fourth step, the first metal 4 and the second metal 11 are melted by a heating (reflow) process to form an intermetallic compound, the bonding material 20 is formed, and the light emitting element 1 and the substrate 13 are bonded. Join. The heating temperature and time at this time are 260 to 335 ° C. and about 100 to 200 seconds.

  During the heating (reflow) treatment, first, the second metal 11 is melted to become liquid and spreads on the substrate 13. When the heating is advanced, the second metal element is sequentially dissolved into the first metal element layer of the first metal 4 with time. Then, heat treatment is performed until the second metal element alone does not exist. Thereafter, it is solidified and an intermetallic compound is formed as the bonding material 20. In this way, the light emitting element 1 is mounted on the substrate 13.

  In this example, the first metal element is Cu and the second metal element is Sn. However, Sn is sequentially dissolved into the Cu layer by the heat treatment, whereby an intermetallic compound of Cu6Sn5 is formed.

DESCRIPTION OF SYMBOLS 1 Light emitting element 2 Reflective layer 3 Diffusion prevention layer 4 1st metal 11 2nd metal 12 Metal part 13 Board | substrate 14 Hotplate 20 Bonding material 30 Light-emitting device 31 Lead 36 Resin molding 39 Sealing member 40 Wire 41 Protection element

Claims (9)

Preparing a light emitting element having a first metal formed on the entire mounting surface;
Preparing a substrate on which a plurality of hemispherical second metals are separated and formed using a dispenser ;
Heat-pressing with a jig so that the upper surface of the second metal is flat;
The first metal and the second metal are brought into contact with each other and heated and melted at a temperature higher than at least one of the melting points of the first and second metals to form an intermetallic compound, so that the substrate and the light emission Bonding the elements;
A method for manufacturing a light-emitting device, comprising: 2. The method of manufacturing a light emitting device according to claim 1, wherein the melting point of the second metal is lower than the melting point of the first metal.   3. The method for manufacturing a light emitting device according to claim 1, wherein the first metal is at least one selected from Cu, Pt, Fe, and Au.   4. The method for manufacturing a light emitting device according to claim 1, wherein the second metal is at least one selected from Sn, In, and Bi. 5.   The method for manufacturing a light emitting device according to claim 1, wherein the light emitting element is provided with a reflective layer and a diffusion prevention layer on the mounting surface.   The light emitting device manufacturing method according to claim 5, wherein the reflective layer is selected from Al and Ag.   The method of manufacturing a light emitting device according to claim 5, wherein the diffusion preventing layer is selected from Ni and Au. The step of bonding the substrate and the light emitting element includes the step of forming the intermetallic compound by melting the second metal and dissolving the second metal in the first metal. The manufacturing method of the light-emitting device as described in any one of.   The method for manufacturing a light-emitting device according to claim 1, wherein in the step of forming the second metal on the substrate, the second metal is formed on the substrate in a plurality of separated shapes.

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