JP2006351611A - Light emitting element mounting substrate and optical semiconductor device using the same - Google Patents

Abstract

【Task】
SUMMARY OF THE INVENTION An object of the present invention is to provide a light emitting element mounting substrate for making an optical semiconductor device with high brightness by increasing reflection at a reflector provided in the vicinity of a light emitting element or reflection at a light emitting element mounting surface, and an optical semiconductor device having high brightness. An optical semiconductor device is provided.
[Solution]
The light emitting element mounting substrate according to the present invention includes a light emitting element mounting including a reflector that surrounds a position where the semiconductor light emitting element is mounted on the substrate and reflects light of the semiconductor light emitting element toward the upper side of the substrate. In the substrate for use, the reflector has a nickel layer and a gold layer or an aluminum layer provided on the nickel layer at least on a reflecting surface.
[Selection] Figure 2

Description

  The present invention relates to a light emitting element mounting substrate for mounting a light emitting element such as a light emitting diode chip on the surface of the substrate, and an optical semiconductor device using the same. The optical semiconductor device is particularly used as a light source for display or illumination.

  A conventional light emitting element mounting substrate is shown in FIG. The light emitting element mounting substrate of FIG. 1 includes a first electrode 13 formed on the substrate, a second electrode 14 formed away from the first electrode 13, and the first electrode 13. In a light emitting element mounting substrate having a light emitting element 15a in which one electrode is conductively connected and the other electrode is conductively connected to the second electrode 14, and a reflector 5 that reflects light of the light emitting element 15a. The reflector 5 is a metal plate laminated on the substrate side while having a reflective surface 5a formed by etching around a position where the light emitting element 15a is mounted (see Patent Document 1). ).

  This light emitting element mounting substrate reflects the light of the light emitting element 15a by the reflecting surface 5a of the reflector 5, and irradiates the light on the upper side of the substrate.

  The reflector 5 of the light emitting element mounting substrate is formed of a metal such as copper, silver, nickel, tin, or a copper alloy (see paragraph number 0054 of the specification of Patent Document 1). Further, in order to increase the reflection efficiency from the first electrode 13, nickel may be deposited on the surface of the first electrode 13. Nickel is supposed to prevent deterioration due to oxidation of copper, which is the material of the first electrode 13, and prevent light reflection efficiency from decreasing due to oxidation (see paragraph number 0070 of the specification of Patent Document 1).

JP 2004-282004 A

  In recent years, development has been progressing so that the central emission wavelength of a semiconductor light-emitting element shifts to 400 to 500 nm, which is the short wavelength side. However, at a blue wavelength of 400 to 500 nm, for example, the light reflectance of nickel is at most 60%. Therefore, in the light emitting element mounting substrate of Patent Document 1, when the reflector 5 made of nickel is provided to reflect the light emitted from the light emitting element to the upper side of the substrate, or nickel is applied to the first electrode 13. When reflecting the light emitted from the light emitting element by vapor deposition to the upper side of the substrate, it cannot always be said that the light is efficiently reflected.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a light emitting element mounting substrate and its optical semiconductor for making an optical semiconductor device with high brightness by making the reflection on the reflector or the reflection on the light emitting element mounting surface highly reflective. Is to provide a device.

  In order to achieve the above object, the present invention provides a light emitting element mounting in which a reflective layer having a very high reflectance is provided on a reflecting surface of a reflector and / or a mounting surface of an optical semiconductor light emitting element at a blue wavelength of 400 to 500 nm It is a substrate, and is an optical semiconductor device in which a semiconductor light emitting element is mounted on the substrate.

  Specifically, the substrate for mounting a light emitting element according to the present invention includes a reflector that surrounds a position where the semiconductor light emitting element is mounted on the substrate and reflects light of the semiconductor light emitting element toward the upper side of the substrate. The reflector includes a nickel layer and a gold layer or an aluminum layer provided on the nickel layer at least on a reflecting surface. Light is reflected with high efficiency on the reflecting surface of the reflector by the nickel layer and the gold layer or aluminum layer provided on the nickel layer.

  The light emitting element mounting substrate according to the present invention includes a reflector that surrounds a position where the semiconductor light emitting element is mounted on the substrate and reflects light of the semiconductor light emitting element toward an upper side of the substrate, A nickel layer is provided on the mounting surface of the semiconductor light emitting element, and a gold layer or an aluminum layer is provided on the nickel layer. Light is reflected with high efficiency on the mounting surface of the semiconductor light emitting element by the nickel layer and the gold layer or aluminum layer provided on the nickel layer.

  In the light emitting element mounting substrate according to the present invention, the reflector is made of a metal plate having an opening hole whose diameter is reduced from the front surface to the back surface, and the semiconductor light emitting element is accommodated in the opening hole. The case where the back surface of the metal plate and the surface of the substrate are fixed is included.

  In the light emitting element mounting substrate according to the present invention, the reflector has an inner wall surface of an opening hole having a diameter reduced in the depth direction provided by etching at a position where the semiconductor light emitting element is mounted. Cases are included.

  In the light emitting element mounting substrate according to the present invention, it is preferable that the depth of the opening hole is larger than the maximum inner diameter of the opening hole. Most of the emitted light is reflected by the inner wall surface of the opening hole, so that high intensity light can be irradiated on the upper side of the substrate.

  The optical semiconductor device according to the present invention is characterized in that a semiconductor light emitting element having a central emission wavelength in the range of 400 to 500 nm is mounted on the light emitting element mounting substrate according to the present invention as the semiconductor light emitting element. By using the light emitting element mounting substrate according to the present invention, light having a central emission wavelength in the range of 400 to 500 nm is reflected to the upper side of the substrate with high reflectivity.

  In the optical semiconductor device according to the present invention, it is preferable that the opening hole has a depth such that the semiconductor light emitting element does not protrude from the opening hole. Most of the emitted light is reflected by the inner wall surface of the opening hole, so that high intensity light can be irradiated on the upper side of the substrate.

  According to the present invention, the efficiency of reflection on a reflector or on a mounting surface of a light-emitting element can be increased, so that an optical semiconductor device with high luminance can be obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited to embodiment shown below. Since the present invention is an optical semiconductor device including a light emitting element mounting substrate and a semiconductor light emitting element mounted thereon, the optical semiconductor device including the light emitting element mounting substrate will be described in detail.

  The light emitting element mounting substrate used in the optical semiconductor device according to the present embodiment is a reflection that surrounds a position where the semiconductor light emitting element is mounted on the substrate and reflects light of the semiconductor light emitting element toward the upper side of the substrate. The reflector includes a nickel layer and a gold layer or an aluminum layer provided on the nickel layer at least on a reflecting surface. Further, a nickel layer is provided on the mounting surface of the semiconductor light emitting element, and a gold layer or an aluminum layer is provided on the nickel layer. Here, the nickel layer and the gold layer or aluminum layer provided on the nickel layer may be provided only on the reflection surface of the reflector, may be provided only on the mounting surface of the semiconductor light emitting element, or Further, it may be provided on both the reflection surface of the reflector and the mounting surface of the semiconductor light emitting element. In the following embodiments, a case where the reflector is provided on both the reflecting surface of the reflector and the mounting surface of the semiconductor light emitting element will be described as an example.

(First embodiment)
The structure of the optical semiconductor device of the present invention will be described with reference to FIGS. FIG. 2 is a schematic perspective view showing the configuration of one form of the optical semiconductor device according to the first embodiment. FIG. 3 is a longitudinal sectional view taken along the line AA ′ in the schematic perspective view of FIG. 2.

  The optical semiconductor device 100 shown in FIG. 2 or 3 has a semiconductor light emitting element 22 mounted on the upper surface of a light emitting element mounting substrate 21. The light emitting element mounting substrate 21 surrounds a position X where the semiconductor light emitting element 22 is mounted on the substrate 23 and reflects the light emitted from the semiconductor light emitting element 22 toward the upper side of the substrate 23 (upward in FIG. 3). A reflector 24 is provided.

  The board | substrate 23 is formed with insulators, such as ceramics and glass epoxy. Moreover, you may use the board | substrate which provided the oxide layer or the ceramic coating layer on the surface of the metal plate. Here, aluminum, copper, stainless steel or the like can be used as the metal plate. 2 or 3, lead frames 25a, 25b, 25c, and 25d are formed on the surface of the substrate 23. FIG. Here, the lead frame 25a and the lead frame 25d are conductively connected by a through hole 26a. The lead frame 25b and the lead frame 25c are conductively connected by a through hole 26b.

The semiconductor light emitting element 22 emits light at a predetermined wavelength by the current supplied through the bonding wires 27a and 27b. In the optical semiconductor device according to the present embodiment, it is desired to mount a semiconductor light emitting element having a central emission wavelength in the range of 400 to 500 nm. The semiconductor light-emitting element 22 is made of a group III nitride compound represented by Al _x Ga _y In _1-xy N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). The following nitride-based semiconductor light-emitting elements When the semiconductor light emitting element 22 includes a semiconductor layer formed on, for example, a sapphire substrate, the semiconductor light emitting element 22 may be directly mounted on the substrate 23, or may be mounted on the lead frame 25a or the lead frame 25b. . When the semiconductor light emitting element 22 includes a semiconductor layer formed on a semiconductor substrate, it is preferable to mount the semiconductor light emitting element 22 on the lead frame 25a or the lead frame 25b in order to reduce the bonding wires 27a and 27b.

  In the optical semiconductor device 100 shown in FIG. 2 or 3, the reflector 24 is formed of a metal plate having an opening hole 28 whose diameter is reduced from the front surface to the back surface. As the material of the metal plate, various metals such as copper, silver, nickel, tin and copper alloy can be used, but copper or copper alloy is preferable.

  The reason why the aperture hole 28 having a reduced diameter is provided in the reflector 24 is to reflect the light emitted from the semiconductor light emitting element 22 toward the upper portion of the substrate by the inner wall surface of the aperture hole 28. The shape of the reduced diameter may be linear, wavy, or stepped. It is sufficient that a part of the inner wall surface of the opening hole 28 of the reflector 24 is a surface that reflects the light emitted from the semiconductor light emitting element 22 toward the upper portion of the substrate. The shape of the cross section of the opening hole 28 may be any shape as long as the inner wall surface of the opening hole 28 becomes the reflecting surface 29, and is a quadrangle in FIG. It may be polygonal, circular or elliptical. Moreover, the opening hole 28 is obtained by punching a metal plate and punching it. Further, a portion corresponding to the opening hole 28 may be dissolved by etching.

  Here, the semiconductor light emitting element 22 needs to be accommodated in the opening hole 28. It is preferable that the position X on which the semiconductor light emitting element 22 is mounted and the axis of the opening hole 28 are overlapped so that the semiconductor light emitting element 22 is disposed substantially at the center of the opening hole 28. After the opening hole 28 and the semiconductor light emitting element 22 maintain the above positional relationship, the back surface of the metal plate as the reflector 24 and the surface of the substrate 23 are fixed. As the fixing method, adhesion with an adhesive, a conductive paste or solder is preferable.

  The reflector 24 has a nickel layer 30 and a gold layer 31 provided on the nickel layer 30 at least on the reflection surface 29. In the case where the reflector 24 is made of a nickel plate, the reflecting surface 29 itself of the reflector 24 is a nickel surface, so that the gold layer 31 may be provided thereon. In the optical semiconductor device 100 of FIG. 2 or FIG. 3, for example, the reflector 24 is formed of a copper plate, and therefore a nickel layer 30 and a gold layer 31 are provided on the reflective surface 29. At a blue wavelength of 400 to 500 nm, for example, nickel has a light reflectance of 60% at most, and copper has a lower light reflectance. Therefore, by providing the nickel layer 30 on the reflecting surface 29 and the gold layer 31 thereon, a light reflectance of 90% or more is secured. The gold layer 31 has a light reflectance of 90% or more at a blue wavelength of 400 to 500 nm. In the present embodiment, an aluminum layer may be used instead of the gold layer 31, and high light reflection can be similarly performed.

  The nickel layer 30 has a thickness of 1 to 5 μm, preferably 2 to 3 μm. The film is formed by various film forming methods such as plating, vapor deposition, and sputtering.

  The gold layer 31 has a thickness of 0.05 to 3 μm, preferably 0.1 to 1.0 μm. The film is formed by various film forming methods such as plating, vapor deposition, and sputtering. A light reflectance of 90% or more can be obtained by setting the gold layer 31 to the above thickness. When the aluminum layer is used instead of the gold layer 31, the thickness is set to 0.05 to 3 μm, preferably 0.1 to 1.0 μm. The film is formed by various film forming methods such as plating, vapor deposition, and sputtering. By replacing the gold layer 31 with the aluminum layer having the above thickness, a light reflectance of 90% or more can be obtained.

  The nickel layer and the gold layer are further provided over the mounting surface of the semiconductor light emitting element 22. Also on this mounting surface, the nickel layer 30 has a thickness of 1 to 5 μm, preferably 2 to 3 μm, by the same film forming method. The gold layer 31 has a thickness of 0.05 to 3 μm, preferably 0.1 to 1.0 μm. Since there is also light emitted toward the mounting surface of the semiconductor light emitting element 22, the luminance of the optical semiconductor device 100 can be increased by highly efficiently reflecting light with a blue wavelength of 400 to 500 nm on the mounting surface. it can. Also on the mounting surface of the semiconductor light emitting element 22, an aluminum layer may be provided on the nickel layer 30 instead of the gold layer 31, and high light reflection can be similarly performed.

  The thickness of the metal plate, that is, the depth of the opening hole 28 (equal to the height of the reflector 24) is, for example, 100 μm to 3 mm, and preferably 200 to 1000 μm. The width of the reflecting surface 29 can be adjusted by this thickness. In addition, since the light emitted from the semiconductor light emitting element 22 is reflected by the reflecting surface 29 and irradiated above the substrate, the opening hole 28 has a depth that prevents the semiconductor light emitting element 22 from protruding from the opening hole 28. It is preferable that For the same reason, the depth of the opening hole 28 is preferably larger than the maximum inner diameter of the opening hole 28, that is, the inner diameter of the opening hole 28 on the surface of the reflector 24. In this way, almost all of the light emitted from the semiconductor light emitting element 22 is irradiated from the opening of the opening hole 28 toward the upper side of the substrate while being reflected or repeatedly reflected by the reflecting surface 29. Therefore, the luminance above the substrate can be increased.

  A sealing portion 32 is formed on the upper surface of the substrate 23 so as to fill the opening hole 28 with a light-transmitting material and cover the semiconductor light emitting element 22. In order to efficiently emit light from the semiconductor light emitting element 22, the refractive index of the material of the sealing portion 32 is preferably close to the semiconductor layer of the semiconductor light emitting element 22. Examples of materials that have a relatively high refractive index and can be easily processed include glass, silicone resin, epoxy resin, and PMMA (polymethyl methacrylate).

  The sealing portion 32 may not be a single material or a single configuration. A plurality of materials may be used, or a plurality of structures may be combined.

  Further, a fluorescent material may be added to the sealing portion 32. Since the fluorescent material has an energy gap smaller than the wavelength of light emitted from the semiconductor light emitting element 22, it can be converted into light having a long wavelength in response to light emitted from the semiconductor light emitting element 22. For example, light from a semiconductor light emitting element that emits blue light may be converted into a complementary color of blue and additively mixed to produce white light, or additive light may be used to output light having various spectra.

  The substrate 23 is provided with a through hole 26a, and the lead frame 25a on the upper surface of the substrate and the lead frame 25d on the lower surface of the substrate are connected by metal wiring covering the inner wall of the through hole 26a. Also, a through hole 26b is provided, and the lead frame 25b on the upper surface of the substrate and the lead frame 25c on the lower surface of the substrate are connected by metal wiring that covers the inner wall of the through hole 26b. By taking out from the optical semiconductor device 100 with such a lead frame, flip-chip connection can be made on a circuit board or a flexible wiring board.

(Second Embodiment)
The reflector 24 of the optical semiconductor device 100 according to the first embodiment is made of a metal plate having an opening 28 whose diameter is reduced from the front surface to the back surface, and the metal plate is fixed to the substrate 23, whereas In the optical semiconductor device according to the second embodiment, the reflector is different in that the reflection surface is an inner wall surface of an opening hole which is provided by etching at a position where the semiconductor light emitting element is mounted and whose diameter is reduced in the depth direction. . The same applies to the semiconductor light emitting device, the lead frame, the through hole, and the substrate, and the same applies to the point that a nickel layer is provided and a gold layer or an aluminum layer is provided on the nickel layer. Hereinafter, the difference will be described.

  In the optical semiconductor device according to the second embodiment, a metal layer is first formed on the substrate 23 by using a film forming method such as a plating method, a vapor deposition method, or a sputtering method. Then, by etching the metal layer, an opening hole whose diameter is reduced in the depth direction is formed, and the inner wall surface of the opening hole is used as a reflection surface. As the metal layer, copper, silver, nickel, tin, copper alloy or the like can be used, but copper or copper alloy is preferable. The structure of the optical semiconductor device according to the second embodiment is the same as the structure shown in FIG. However, in the optical semiconductor device 100 according to the first embodiment, the metal plate is fixed to the substrate using, for example, an adhesive, a conductive paste, or solder. However, in the optical semiconductor device according to the second embodiment, the metal plate is attached to the upper surface of the substrate. Since the metal layer is formed by a film forming method such as a plating method, the reflector is laminated and integrated with the substrate.

  Next, a method for manufacturing the optical semiconductor device 100 according to the first embodiment will be described. 4 (1) to 4 (4) are views for explaining a method of manufacturing the optical semiconductor device 100 according to the first embodiment. 4 (1) to 4 (4), the same reference numerals as those in FIG. 2 or 3 represent the same meaning.

  First, a through hole 26 penetrating the substrate 23 on which a plurality of semiconductor light emitting elements 22 can be mounted is formed, and the inner wall of the through hole 26 is plated with a metal to connect the upper surface and the lower surface of the substrate 23. Is formed (FIG. 4 (1)). Lead frames 25a, 25b, 25c, and 25d are formed in a predetermined pattern on the upper and lower surfaces of the substrate 23 (FIG. 4A). Either the wiring formation on the inner wall of the through hole 26 or the lead frames 25a, 25b, 25c, 25d may be formed first.

  Next, the nickel layer 30 is formed on the upper surface of the substrate 23 at least around the position where the semiconductor light emitting element 22 is to be mounted by a film forming method such as a plating method, a vapor deposition method, or a sputtering method. Next, a gold layer 31 or an aluminum layer is formed on at least the surface of the nickel layer 30 by a film forming method such as a plating method, a vapor deposition method, or a sputtering method (FIG. 4A).

  Next, the semiconductor light emitting elements 22 are respectively mounted on the upper surface of the substrate 23. The electrode of each semiconductor light emitting element 22 and the lead frame 25a are conductively connected by a bonding wire 27a, and the electrode of each semiconductor light emitting element 22 and the lead frame 25b are conductively connected by a bonding wire 27b.

  Next, the reflector 24 having a predetermined shape is mounted on the substrate 23 (FIG. 4B). The reflector 24 is formed by punching a metal plate by punching to form an opening hole 28, and the inner wall surface of the opening hole 28 is used as a reflecting surface. By reducing the diameter of the convex mold of the puncher as it approaches the front end surface, a metal plate having an opening hole 28 whose diameter is reduced from the front surface to the back surface is obtained. Alternatively, the opening hole 28 may be formed by etching by masking a portion other than the portion where the opening hole 28 is provided. In the vicinity of the opening portion of the masking, the erosion in the side surface direction of the opening hole 28 proceeds, so that a metal plate having the opening hole 28 with a reduced diameter is obtained in the same manner as punching. The metal plate is mounted on the substrate 23 by, for example, bonding means using an adhesive, a conductive paste or solder. Next, the nickel layer 30 is formed on at least the inner wall surface of the opening hole 28 by a film forming method such as a plating method, a vapor deposition method, or a sputtering method. If the metal plate is a nickel plate, this step may be omitted. Next, a gold layer 31 or an aluminum layer is formed on at least the surface of the nickel layer 30 by a film forming method such as a plating method, a vapor deposition method, or a sputtering method. The formation of the nickel layer 30 and the gold layer 31 or the aluminum layer on the inner wall surface of the opening hole 28 may be performed before the metal plate is mounted on the substrate 23.

  For example, PMMA, which is a material for the sealing portion 32, is filled in the opening 28 of the reflector 24 and cured (FIG. 4C). Thermal curing or ultraviolet curing may be used.

  Each optical semiconductor device 100 is cut out by a cutting line passing through the through hole 26 (FIG. 4D). Cutting may be thermal cutting with a laser or mechanical cutting with dicing. The through hole 26 is divided in the direction of the hole, and the wiring on the inner wall that is halved connects the lead frames on both sides of the substrate 23. The reflector may be cut when the substrate 23 is cut out, or the reflector 24 (metal plate) separated in FIG. 4B may be mounted on the substrate 23.

  With such a manufacturing method, it is possible to mass-produce an optical semiconductor device capable of increasing the light emission efficiency and obtaining a stable emission efficiency.

  Next, a method for manufacturing an optical semiconductor device according to the second embodiment will be described. The optical semiconductor device according to the second embodiment can be manufactured by applying the method for manufacturing a light emitting element mounting substrate described in Patent Document 1, for example. Specifically, the description of paragraph numbers 0044 to 0065 of Patent Document 1 is applied. At this time, after the metal layer is etched to form the opening hole, the next step is provided. That is, a nickel layer is formed on at least the inner wall surface of the opening hole by a film forming method such as a plating method, a vapor deposition method, or a sputtering method. When the metal layer is formed of nickel, the formation of the nickel layer may be omitted. Next, a gold layer or an aluminum layer is formed at least on the surface of the nickel layer by a film forming method such as a plating method, a vapor deposition method, or a sputtering method. By adding this step, the optical semiconductor device according to the second embodiment can be manufactured.

  The optical semiconductor device of the present invention can be used as a light source mounted on lighting, communication, sensors, display devices, and the like.

It is a figure explaining the structural example of the conventional optical semiconductor device. 1 is a schematic perspective view of an optical semiconductor device according to an embodiment of the present invention. In the schematic perspective view of FIG. 2, it is the longitudinal cross-sectional schematic diagram of the A-A 'line. It is a figure explaining the manufacturing method of the optical semiconductor device concerning a 1st embodiment.

Explanation of symbols

100 optical semiconductor device 13 first electrode 14 second electrode 15a light emitting element 21 light emitting element mounting substrate 22 semiconductor light emitting element 23 substrates 5, 24 reflectors 25a, 25b, 25c, 25d lead frames 26, 26a, 26b through holes 27a, 27b Bonding wire 28 Opening holes 5a, 29 Reflecting surface 30 Nickel layer 31 Gold layer 32 Sealing portion

Claims (7)

In the light emitting element mounting substrate comprising a reflector that surrounds a position where the semiconductor light emitting element is mounted on the substrate and reflects the light of the semiconductor light emitting element toward the upper side of the substrate,
The light-emitting element mounting substrate, wherein the reflector includes a nickel layer and a gold layer or an aluminum layer provided on the nickel layer on at least a reflection surface. In the light emitting element mounting substrate comprising a reflector that surrounds a position where the semiconductor light emitting element is mounted on the substrate and reflects the light of the semiconductor light emitting element toward the upper side of the substrate,
A substrate for mounting a light emitting element, wherein a nickel layer is provided on a mounting surface of the semiconductor light emitting element, and a gold layer or an aluminum layer is provided on the nickel layer.   The reflector is made of a metal plate having an opening hole whose diameter is reduced from the front surface to the back surface, and the back surface of the metal plate and the surface of the substrate are in a positional relationship in which the semiconductor light emitting element is accommodated in the opening hole. The light emitting element mounting substrate according to claim 1, wherein the light emitting element mounting substrate is fixed.   3. The reflector according to claim 1, wherein an inner wall surface of an opening hole having a diameter reduced in a depth direction provided by etching at a position where the semiconductor light emitting element is mounted is used as a reflecting surface. The light emitting element mounting substrate as described.   The light emitting element mounting substrate according to claim 3 or 4, wherein a depth of the opening hole is larger than a maximum inner diameter of the opening hole.   6. A light comprising a light emitting element mounting substrate according to claim 1, wherein a semiconductor light emitting element having a central light emission wavelength in a range of 400 to 500 nm is mounted as the semiconductor light emitting element. Semiconductor device. The optical semiconductor device according to claim 6, wherein the opening hole has a depth such that the semiconductor light emitting element does not protrude from the opening hole.

Images