JP2012079776A - Semiconductor light-emitting device and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED device that prevents uselessness of phosphor, has excellent luminous efficiency, and can be manufactured easily even if the device has phosphor and a structure in which side surfaces of an LED element are buried in a white (reflective) member.SOLUTION: An LED element 21 is flip-chip mounted on a circuit board 22. The LED element 21 has a phosphor layer 15 on the surface opposite to the mounting surface of the circuit board 22, and a white member 11 surrounds the side surfaces of the LED element 21 and the phosphor layer 15. The top surfaces of the phosphor layer 15 and the white member 11 are substantially aligned.

Description

  The present invention relates to a semiconductor light-emitting device in which a semiconductor light-emitting element is flip-chip mounted on a circuit board and a manufacturing method thereof.

  2. Description of the Related Art Among semiconductor light emitting devices (hereinafter referred to as LED devices unless otherwise specified) in which a semiconductor light emitting element (hereinafter referred to as an LED device) is mounted on a circuit board, an LED device provided with a reflective member on the side surface of the LED element Is known (for example, Patent Document 1).

  FIG. 4 of Patent Document 1 is shown in FIG. FIG. 4 is a cross-sectional view of the LED device in which the first sealing resin 6 containing the reflective agent fills the periphery of the LED chip 4 (LED element). The LED chip 4 is disposed in the center of a reflector case 1 made of a ceramic material, and the reflector case 1 includes a square pyramid-shaped opening 2. The LED chip 4 is die-bonded to the lead frame 3 a, and the upper surface electrode of the LED chip 4 is connected to the lead frame 3 b by a bonding wire 5. The first sealing resin 6 and the LED chip 4 are covered with a second sealing material 7 made of a transparent resin or a transparent resin obtained by mixing a transparent resin with a diffusion material.

  The LED chip 4 emits blue light from the epitaxial light emitting layer and emits yellow light from the ZnSe substrate. Of the yellow light and blue light, the light directed to the side is reflected by the reflective material of the first sealing resin 6 and returned to the LED chip 4. The downward light is reflected by a reflective layer (not shown) formed on the bottom surface of the LED chip 4. In this way, all of blue light and yellow light are finally emitted from the upper surface of the LED chip 4. As a result, two-color mixing is effectively performed, and high brightness white light is obtained.

JP 2002-43625 A (FIG. 1)

  The LED device of FIG. 4 is not a combination of a blue (or near-ultraviolet) light emitting diode and a phosphor, which have become mainstream in recent years. For this LED device, if the LED chip 4 is replaced with a blue LED element and the second sealing resin 7 is mixed with a phosphor that emits yellow light, the LED element emits white light with a structure in which a reflecting member is provided on the side surface. An LED device is obtained. However, in the structure in which the reflecting member is provided on the side surface of the LED element, the light emitted from the LED element is unevenly distributed above the LED element, so that there is a problem that the phosphors in the region other than the LED element do not function and are wasted. .

  Therefore, the present invention provides an LED device that has not only a small waste of the phosphor but also good luminous efficiency and is easy to manufacture even if it includes a white (reflective) member that fills the side surfaces of the phosphor and the LED element, and a method for manufacturing the LED device. The purpose is to provide.

In order to solve the above problems, a semiconductor light emitting device of the present invention is a semiconductor light emitting device in which a semiconductor light emitting element is mounted on a circuit board.
The semiconductor light emitting device is flip-chip mounted on the circuit board, and includes a phosphor layer on the surface opposite to the mounting surface,
A white member surrounds the sides of the semiconductor light emitting device and the phosphor layer;
The upper surface of the phosphor layer is substantially coincident with the upper surface of the white member.

  An inorganic binder that becomes glassy when the binder of the white member is sintered may be used.

  The binder of the white member may be a silicone resin.

  It is preferable that the white member is filled in a gap between the semiconductor light emitting element and the circuit board.

In order to solve the above problems, a method for manufacturing a semiconductor light emitting device of the present invention is a method for manufacturing a semiconductor light emitting device in which a semiconductor light emitting element is mounted on a circuit board.
A wafer preparation step of preparing a wafer in which the semiconductor light emitting elements are connected and arranged; and
A phosphor layer forming step of forming a phosphor layer on the surface of the wafer opposite to the mounting surface of the semiconductor light emitting element;
LED element singulation step of cutting the wafer into pieces of the semiconductor light emitting elements;
A mounting step of flip-chip mounting the semiconductor light emitting element on a collective substrate connected to the circuit board;
An application step of applying a white member containing reflective fine particles to the entire surface of the aggregate substrate;
A polishing step of polishing the white member;
And a singulation process for separating the semiconductor light emitting device into a single piece.

  You may provide the fluorescent substance layer grinding | polishing process of grind | polishing the said fluorescent substance layer after the said fluorescent substance layer formation process.

  You may provide the transparent resin application | coating process which apply | coats transparent resin before the said singulation process.

  An inorganic binder that becomes glassy when the binder of the white member is sintered may be used.

  The binder of the white member may be a silicone resin.

  In the semiconductor light emitting layer device of the present invention, a semiconductor light emitting element having a phosphor layer on the upper surface is flip-chip mounted on a circuit board, and the side surfaces of the phosphor layer and the semiconductor light emitting element are filled with a white member containing reflective fine particles. The upper surfaces of the phosphor layer and the white member are substantially matched. Usually, a semiconductor light emitting element for flip chip mounting has a transparent substrate on the upper side (light emitting side) and a semiconductor layer on the lower side (mounting side) (there may be no transparent substrate). Since the phosphor layer is formed only directly above the transparent substrate, all the phosphors are involved in wavelength conversion, and there is no waste and only a small amount is required. In addition, since it is flip-chip mounted, the shadow caused by the bonding wire is eliminated and the light emission efficiency is improved. Even if the white member is arranged by a simple coating method, the upper surface of the white member and the upper surface of the phosphor layer can be easily matched by polishing. As described above, the semiconductor light emitting device of the present invention is not only small in waste of the phosphor but also good in luminous efficiency and easy to manufacture even if the side surface of the semiconductor light emitting element is filled with the white member and the phosphor layer is provided. become.

In the method for manufacturing a semiconductor light emitting device of the present invention, a phosphor layer is formed at a wafer stage, a semiconductor light emitting element is flip-chip mounted on an aggregate substrate connected to a circuit board, and then the reflective fine particles are contained in the aggregate substrate. The upper surface of the semiconductor light emitting element is exposed by applying and polishing a white member. As described above, the semiconductor light-emitting device of the present invention forms a phosphor layer at the wafer stage where the semiconductor light-emitting elements are arranged at a high density, so that the manufacturing efficiency is high and the phosphor is not wasted. Furthermore, since the phosphor layer and the side surface of the semiconductor light emitting device are filled and coated with a white member, the assembly substrate is coated and polished, so that it is easy to manufacture, and since there is no bonding wire as described above, the light emission efficiency is not impaired.

Sectional drawing of the LED apparatus in embodiment of this invention. The elements on larger scale of FIG. Explanatory drawing of the manufacturing method of the LED apparatus shown in FIG. Sectional drawing of the conventional LED device.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. In the description of the drawings, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted. For the sake of explanation, the scale of the members is changed as appropriate.

  FIG. 1 is a cross-sectional view of an LED device 10 (semiconductor light emitting device) of the present embodiment. In the LED device 10, an LED element 21 (semiconductor light emitting element) is flip-chip mounted on a circuit board 22. The electrode 17 formed on the upper surface of the plate material 20 in the circuit board 22 is connected to the electrode 19 formed on the lower surface of the plate material 20 through the through hole 18. In the LED element 21, a semiconductor layer 13 is formed on the lower surface of the sapphire substrate 12, and two bumps 14 are attached to the semiconductor layer 13. The semiconductor layer 13 is a diode provided with a light emitting layer, and each bump 14 corresponds to an anode and a cathode. The bumps 14 are connected to the electrodes 17 by metal eutectic bonding.

  The phosphor layer 15 exists on the upper surface of the sapphire substrate 12, and the white silicone resin 11 (white member) surrounds the LED element 21 and the side surfaces of the phosphor layer 15. The upper surface of the phosphor layer 15 and the upper surface of the white silicone resin 11 coincide with each other, and the transparent resin layer 16 is laminated on each upper surface. The white silicone resin 11 is also filled in the gap between the LED element 21 and the circuit board 22.

  The LED element 21 is a blue light emitting diode. The phosphor layer 15 contains a YAG phosphor and emits yellow light with blue light emitted from the LED element 21. That is, the light emitting color (blue) of the LED element 21 and the light emitting color (yellow) of the phosphor are mixed to obtain white light. The white member 11 is obtained by kneading titanium oxide (reflective fine particles) with a silicone resin (binder) and curing it by heating. The transparent resin 16 is made of a silicone resin.

  The plate member 20 has a thickness of several hundred μm and is selected from resin, ceramic, and metal in consideration of thermal conductivity. The electrodes 17 and 19 are formed by laminating a nickel layer and a gold layer on a copper foil of about 20 μm, for example. When the plate material 20 is resin, the through hole 18 is preferably filled with a metal paste to improve thermal conductivity. The sapphire substrate 12 has a thickness of 80 to 120 μm, the semiconductor layer 13 has a thickness of about 7 μm, and the bump 14 has a thickness of about 10 to 30 μm if formed by electrolytic plating. In order to efficiently direct the light emitted downward from the LED element 21 upward, the thickness of the white silicone resin 11 filled between the LED element 21 and the circuit board 22 is preferably 30 μm or more. The phosphor layer 15 has a thickness of about 100 μm, and the transparent resin layer 16 has a thickness of several tens of μm.

The state of light emitted from the LED device 10 will be described with reference to FIG. FIG. 2 is obtained by adding blue light beams L1 and L2 emitted from the semiconductor layer 13 to the enlarged view of the region surrounded by A in FIG. Of the blue light emitted from the semiconductor layer 13, the light ray L <b> 1 is emitted from the LED device 10 through the sapphire substrate 12, the phosphor layer 15, and the transparent resin layer 16. The light beam L2 passes through the side surface of the sapphire substrate 12 and enters the white silicone resin 11, where it is reflected by the reflective fine particles, returns to the sapphire substrate 12 again, passes through the phosphor layer 15 and the transparent resin layer 16, and is emitted from the LED device 10. . A downward light beam (not shown) is reflected on the lower white silicone resin 11, the bump 14, or the LED chip 21 for flip chip mounting (not shown, the LED chip for flip chip mounting includes a reflecting layer). ) And reflect upwards. As described above, the light beams L1, L2, and the like emitted from the semiconductor layer 13 of the LED element 21 are emitted from the LED device 10 through the upper surface of the sapphire substrate 12 except for losses such as absorption. In the phosphor layer 15, part of the blue light is wavelength-converted by the phosphor, and whitened by additive mixing of the wavelength-converted light and the blue light. The light emission of the phosphor layer 15 is isotropic, but the downward light beam is directed upward in the same manner as the blue light (light beams L1, L2, etc.) described above.

  A method of manufacturing the LED device 10 of this embodiment will be described with reference to FIG. FIG. 3 is an explanatory diagram of a method for manufacturing the LED device 10. (A) is a wafer preparation process in which the LED elements 21 are connected and arranged to prepare the wafer 31 made of the sapphire substrate 12. A semiconductor layer 13 (not shown) is formed on the lower surface of the wafer 31, and bumps 14 are attached to each LED element region.

  (B) is a phosphor layer forming step for forming the phosphor layer 15 on the surface opposite to the mounting surface of the LED element 21, that is, on the upper surface of the wafer 31. The phosphor layer 15 may be applied by a printing method. The phosphor layer 15 uses an inorganic binder (for example, organopolysiloxane) so as to withstand high temperatures (about 300 ° C.) applied in the mounting process of the LED element 21 described later. This binder is cured at about 150 ° C. by a catalyst.

  (C) is a phosphor layer polishing step for polishing the phosphor layer 15 after the aforementioned phosphor layer forming step. In order to obtain white with a desired chromaticity, it is necessary to adjust the thickness of the phosphor layer 15. The polishing for adjusting the thickness may be grinding that is widely used in wafer back grinding and the like.

  (D) is an LED element separation step in which the wafer 31 is cut to separate the LED elements 21. When the wafer 31 is attached to a dicing sheet (not shown), the wafer 31 is cut by a dicing apparatus, and the dicing sheet is expanded, each LED element 21 is separated and can be picked up.

  (E) is a mounting process in which the LED elements 21 are flip-chip mounted on the collective substrate 23 connected to the circuit board 22. The collective substrate 23 is provided with a large number of circuit board regions on a large plate member 20, and an electrode 17, a through hole 18 (not shown), and an electrode 19 (not shown) are formed in each circuit board region. The LED elements 21 may be arranged on the collective substrate 23 one by one, or the LED elements 21 are arranged on the adhesive sheet in advance according to the electrode pitch of the collective substrate 23, and this adhesive sheet is stacked on the collective substrate 23. A large number of LED elements 21 may be collectively arranged on the collective substrate 23. When the arrangement of the LED 21 is completed, the LED element 21 is pressurized and heated to be joined to the electrode 17.

  (F) is an application process in which the white silicone resin 11 containing reflective fine particles is applied to the entire surface of the collective substrate 23. Since the white silicone resin 11 may cover the LED element 21, the white silicone resin 11 may be disposed on the collective substrate 23 using a squeegee. Finally, the white silicone resin 11 is heated and cured at about 150 ° C.

  (G) is a polishing step for polishing the white silicone resin 11. Polishing is performed until the white silicone resin 11 coincides with the upper surface of the phosphor layer 15. At this time, even if the upper surface of the phosphor layer 15 is polished to some extent (about several μm), there is no significant change in chromaticity.

(H) is a transparent resin coating step in which a transparent resin is applied to form the transparent resin layer 16. The transparent resin layer 16 functions as a mechanical protection and gas barrier for the phosphor layer 15. The transparent resin may be silicone and is cured after application.

  (I) is an individualization process for separating the LED device 10 into single pieces from the collective substrate 23. The collective substrate 23 formed up to the transparent resin layer 16 is cut by a dicing device to divide the LED device 10 into individual pieces.

  In the present embodiment, a phosphor layer polishing step is provided after the phosphor layer forming step. When it is not necessary to finely adjust the white chromaticity, the phosphor layer polishing step can be omitted. In addition, when a silicate green phosphor and a nitride red phosphor are combined as the phosphor, it is necessary to consider the influence of the peak wavelength of the LED element 21 to determine the thickness of the LED layer 15. .

  In this embodiment, the white silicone resin 11 polishing step (g) is provided after the white silicone resin 11 coating step (f). The polishing step (g) can be omitted if the coating amount is controlled with a high-precision dispenser and the upper surface of the white silicone resin 11 and the upper surface of the LED element 21 are substantially matched. Similarly, in this embodiment, the phosphor layer polishing step (c) after the phosphor layer forming step (b) can be omitted if a highly accurate dispenser is used. However, the polishing process of the wafer 31 in which the LED elements 21 are densely packed and the polishing process of the collective substrate 23 in which a large number of LED devices 10 are arranged as in the present embodiment are performed in a lump, and thus do not impose a large load on manufacturing. . The transparent resin layer 16 and the transparent resin coating step (h) can also be omitted when the phosphor layer 15 has sufficient strength and the environment resistance (especially moisture) of the phosphor is high.

  In this embodiment, the binder is a silicone resin as the white member. The white member may be a white ceramic ink obtained by kneading and solidifying an inorganic binder that becomes glassy when sintered, such as organopolysiloxane, and reflective fine particles. This white ceramic ink is cured at about 150 ° C. by a catalyst. The white ceramic ink is also characterized by little light degradation because the binder is inorganic.

  In the present embodiment, when the white silicone resin 11 is polished in the polishing step (g) of FIG. 3, the upper surface of the phosphor layer 15 may be polished somewhat (about several μm). However, when polishing of the phosphor layer 15 is not preferable, a thin transparent resin layer may be formed after the phosphor layer polishing step (c). In this case, when the white silicone resin 11 is polished in the polishing step (g), the upper surface of the transparent resin layer is slightly polished (about several μm), and the phosphor layer 15 is not polished. As described above, when the luminous efficiency of the phosphor layer 15 changes due to the emission spectrum (emission peak wavelength, etc.) of the LED element 21 as described above, the thickness of the phosphor layer 15 is adjusted in advance for each LED element 21. This is effective when correcting the chromaticity of the LED element 21.

  In the present embodiment, the LED element 21 emits blue light, but the LED element 21 may emit near ultraviolet light. In this case, the phosphor layer 15 is kneaded with a blue phosphor, a green phosphor and a red phosphor. At this time, not only the color rendering property of visible light is improved, but also the color emission due to the azimuth angle is reduced because the light emitting portion is only the upper surface of the LED element 21.

  In the present embodiment, the white member 11 is a single layer, but the white member may be two or more layers. For example, the lower layer is a white silicone resin and the upper layer is a white ceramic ink. In this structure, the soft white silicone resin serves as a buffer layer against stress, and the problem that the hard white ceramic ink breaks due to the thermal expansion of the circuit board can be avoided. Alternatively, the viscosity of the white silicone resin (before curing) may be lowered to make it easier to enter the lower surface of the LED element (at the same time the ambient pressure may be increased). Even when the sapphire substrate (transparent substrate) is made as thin as possible (for example, 10 to 20 μm), the production method of the present invention is effective for facilitating the production.

10 ... LED device (semiconductor light-emitting device),
11 ... White silicone resin (white member),
12 ... sapphire substrate,
13 ... semiconductor layer,
14 ... Bump,
15 ... phosphor layer,
16 ... Transparent resin layer,
17, 19 ... electrodes,
18 ... Through hole,
20 ... plate material,
21 ... LED element (semiconductor light emitting element),
22 ... circuit board,
23 ... Collective board,
L1, L2 ... rays.

Claims (9)

In a semiconductor light emitting device in which a semiconductor light emitting element is mounted on a circuit board,
The semiconductor light emitting device is flip-chip mounted on the circuit board, and includes a phosphor layer on the surface opposite to the mounting surface,
A white member surrounds the sides of the semiconductor light emitting device and the phosphor layer;
A semiconductor light emitting device, wherein an upper surface of the phosphor layer and an upper surface of the white member are substantially coincident with each other.   The semiconductor light emitting device according to claim 1, wherein the white material binder is an inorganic binder that becomes glassy when sintered.   The semiconductor light emitting device according to claim 1, wherein the binder of the white member is a silicone resin.   4. The semiconductor light emitting device according to claim 1, wherein the white member is filled in a gap between the semiconductor light emitting element and the circuit board. 5. In a method for manufacturing a semiconductor light emitting device in which a semiconductor light emitting element is mounted on a circuit board,
A wafer preparation step of preparing a wafer in which the semiconductor light emitting elements are connected and arranged; and
A phosphor layer forming step of forming a phosphor layer on the surface of the wafer opposite to the mounting surface of the semiconductor light emitting element;
LED element singulation step of cutting the wafer into pieces of the semiconductor light emitting elements;
A mounting step of flip-chip mounting the semiconductor light emitting element on a collective substrate connected to the circuit board;
An application step of applying a white member containing reflective fine particles to the entire surface of the aggregate substrate;
A polishing step of polishing the white member;
A method for manufacturing a semiconductor light emitting device, comprising: a step of separating the semiconductor light emitting device into a single piece.   6. The method of manufacturing a semiconductor light emitting device according to claim 5, further comprising a phosphor layer polishing step for polishing the phosphor layer after the phosphor layer forming step.   The method for manufacturing a semiconductor light emitting device according to claim 5, further comprising a transparent resin application step of applying a transparent resin before the individualization step.   The method for manufacturing a semiconductor light emitting device according to claim 5, wherein the white material binder is an inorganic binder that becomes glassy when sintered. The method for manufacturing a semiconductor light emitting device according to claim 5, wherein the binder of the white member is a silicone resin.

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