JP2002094123A - Surface-mounted light emitting diode and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-mounted light emitting diode having a wavelength conversion board for obtaining a uniform emission luminance without causing a color irregularity. SOLUTION: A gallium nitride compound semiconductor has a light emitting layer 27 composed of an n-type semiconductor 23 and a p-type semiconductor 24, an n-type electrode 25, and a p-type electrode 26. All elements are formed on the surface of an element substrate 22 made of sapphire glass. A light emitting element chip 21 is formed with a zinc selenide compound semiconductor- made wavelength conversion board 28 adhered to the backside of the element board 22. The chip 21 is mounted on a circuit board 31 having outer connection electrodes 32, 33 to form a surface mount type light emitting diode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode which emits white light, and more particularly to a surface mount type light emitting device in which a wavelength conversion substrate for converting to white light is formed integrally with an element substrate on which a light emitting layer is formed. The present invention relates to a diode and a method for manufacturing the diode.

[0002]

2. Description of the Related Art Heretofore, as a light emitting diode which emits white light, for example, a light emitting diode in which a blue light emitting element made of a gallium nitride compound semiconductor is used as a light emitting medium and a yellow fluorescent material is combined with this light emitting medium is known. I have. FIG. 10 shows such a conventional light emitting diode that converts the wavelength of blue light emission into white light emission. This light emitting diode 1
Is a concave portion 3 provided in the metal stem 2 by the light emitting element chip 4.
And connected to the metal post 5 by a bonding wire 6. The light emitting element chip 4 and the bonding wires 6 are sealed with a bullet-shaped transparent resin body 8. The recess 3 is filled with a fluorescent material-containing resin 7 in which a fluorescent material is dispersed so as to cover the light emitting element chip 4. In the light emitting diode 1 having such a configuration, the blue light emitted from the light emitting element chip 4 hits the fluorescent material dispersed in the fluorescent material containing resin 7 to excite the fluorescent material, and the light emitting element chip 4 Is converted to yellow-based light emission different from the light-emission color, and white-based light is obtained by mixing the two colors (Japanese Patent Laid-Open No. 7-99).
No. 345).

[0003]

However, in the light emitting element chip 4 as described above, since the fluorescent substance is dispersed in the resin mold by insert molding, the difference in specific gravity between the fluorescent substance and the resin mold is caused. As a result, there is a problem that the fluorescent substance is biased to one side, causing a variation in luminance and an uneven color tone.

In addition, since the connection between the light emitting element chip 4 and the external electrodes is made through the bonding wires 6, there are also problems in that many steps and auxiliary materials are required, and the product cost is increased.

[0005] In the conventional insert molding, light emitting diodes can be manufactured only in units of several tens at a time, which is not suitable for mass production.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a surface-mounted type light emitting device having a wavelength conversion substrate capable of obtaining uniform light emission luminance without color tone unevenness, simplifying a manufacturing process, and mass-producing. A diode and a method for manufacturing the same are provided.

[0007]

Means for Solving the Problems To solve the above problems, the present inventors have attempted to make the emission luminance uniform by integrally providing a wavelength conversion substrate on an element substrate on which a light emitting layer is formed. . Specifically, the invention according to claim 1 is a gallium nitride-based compound semiconductor in which an element substrate is made of sapphire glass and a light emitting layer and an electrode are formed on the surface thereof.
The above-mentioned problem has been solved by a surface-mounted light-emitting diode including a light-emitting element chip in which a wavelength conversion substrate formed of a zinc selenide-based compound semiconductor is bonded and fixed to the back surface of the element substrate.

According to the present invention, since the wavelength conversion substrate formed of a zinc selenide-based compound semiconductor is directly adhered and fixed to the back surface of the element substrate with the transparent adhesive, the light emission layer on the surface of the element substrate emits light. The emitted light efficiently passes through the element substrate and the wavelength conversion substrate, which are light emitting media, and the attenuation of the light amount can be suppressed. For this reason, even in wavelength conversion, a decrease in light amount and uneven color tone can be prevented, and blue light and yellow light can be efficiently mixed to obtain uniform white light emission. Also,
Conventionally, a powdery phosphor has been used as a wavelength conversion material and blended with a mold resin to form a wavelength conversion layer. However, in this blending method, dispersion tends to be non-uniform. As a result, variations in brightness and uneven color tone were generated, and uniform white light emission was not obtained. However, as in the present invention, a substrate of a zinc selenide-based compound semiconductor in which fluorescent particles were uniform crystals was directly disposed. By doing so, it is difficult for variations in the light emission luminance to occur, and white light emission with a stable color tone can be obtained.

According to a second aspect of the present invention, in the surface mount type light emitting diode according to the first aspect, the light emitting element chip is mounted on a circuit board upside down, and the electrodes of the light emitting element chip are bumped on the circuit board. And the light emitting element chip is resin-sealed on the circuit board surface.

According to the present invention, the light emitting element chip is placed upside down on the circuit board to form a laminated structure of a circuit board, electrodes, a light emitting layer, an element substrate, and a wavelength conversion board from the bottom. Become. Further, since the circuit board and the electrodes are connected via the bumps, there is no obstacle such as a wire in the resin covering the light emitting element chip. For this reason, the light emitted from the light emitting layer can reach the wavelength conversion substrate directly through the element substrate without being blocked by the electrodes, wires, or the like. Specifically, the element substrate is sapphire glass, and blue light emitted through the sapphire glass excites the fluorescent particles of the zinc selenide-based compound semiconductor forming the wavelength conversion substrate, so that the light emitting element chip The light is converted to yellow light that is different from the original blue light. And
Uniform white light emission can be obtained by mixing these two colors.

According to a third aspect of the present invention, there is provided a method of manufacturing a surface mount type diode, comprising a step of forming a long groove-shaped through-hole in a collective circuit board, an electrode pattern connected to the through-hole in a matrix, and sapphire glass. A step of placing the gallium nitride-based compound semiconductor on which the light emitting layer and the electrode are formed on the surface of the element substrate upside down on the electrode pattern, and electrically connecting the electrode and the electrode pattern via bumps; Forming a light-emitting element chip assembly by bonding and fixing a wavelength conversion substrate formed of a zinc selenide-based compound semiconductor on an upper surface of an element substrate of a gallium nitride-based compound semiconductor mounted on the collective circuit board; Disposing a mold on the collective circuit board, filling the mold with a resin to seal the light emitting element chip assembly, and after curing the resin, Characterized by comprising a step of dividing the set circuit board for each of the light emitting diode.

According to the present invention, a large number of light emitting diodes can be produced from one integrated circuit board. Further, since the flip-chip mounting method using bumps is used, a wire bonding step is not required. For this reason, the manufacturing method is simple, manufacturing equipment and man-hours are reduced, connection failures and the like are less likely to occur, and the product yield is improved.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a surface-mounted light emitting diode and a method for manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a light emitting element chip constituting the surface mounted light emitting diode, FIG. 2 is a perspective view of the surface mounted light emitting diode of the present invention, and FIG. 3 shows a case where the surface mounted light emitting diode is mounted on a motherboard. 4 to 9 are cross-sectional views showing the steps of manufacturing the surface-mounted light emitting diode.

As shown in FIG. 1, a light-emitting element chip 21 mounted on a surface-mount type light-emitting diode of the present invention is a blue light-emitting element having a substantially square shape whose light-emitting source is made of a gallium nitride-based compound semiconductor. This blue light emitting element has a
A light emitting layer 27 composed of an n-type semiconductor 23 and a p-type semiconductor 24 is diffused and grown on the lower surface of an element substrate 22 made of a transparent sapphire glass having a thickness of about m. The n-type semiconductor 23 and the p-type semiconductor 24
Is formed to have a thickness of about several μm, and an n-type electrode 25 and a p-type electrode 26 are formed on the lower surfaces thereof. The n-type electrode 25 is formed of gold (Au) on the cathode side, and the p-type electrode 26 is formed of aluminum (Al) and connected to the anode side. The n-type electrode 25 and the p-type electrode 26 can be formed to desired sizes by sputtering or vacuum deposition.

On the upper surface of the element substrate 22, a solid-state wavelength conversion substrate 28 is integrally joined with the element substrate 22. The wavelength conversion substrate 28 is a 100-200 μm-thick zinc selenide-based compound semiconductor substrate mounted on the entire upper surface of the element substrate 22, and the blue light emitted from the light emitting layer 27 is emitted through the element substrate 22. Then, the fluorescent particles in the substrate of the zinc selenide-based compound semiconductor are excited to be converted to a fluorescent color, and white light is obtained by mixing the original blue light and the converted fluorescent color.

The above-described wavelength conversion substrate 28 is formed by bonding with a transparent adhesive (not shown) so as to cover the entire upper surface of the element substrate 22.

Accordingly, in the light emitting element chip 21 having the above-described configuration, blue light is emitted upward, sideward, and downward from the boundary surface between the n-type semiconductor 23 and the p-type semiconductor 24. In particular, the blue light emitted upward is emitted from the element substrate 22.
, And excites the minute fluorescent particles in the wavelength conversion substrate 28, whereby the wavelength is converted into long-wavelength visible light. The wavelength-converted emission color is yellow, but the color tone of white emission obtained by mixing with the original blue light varies depending on the thickness of the zinc selenide-based compound semiconductor that is the material of the wavelength conversion substrate 28. . For example, the sliced 100 μm of the present embodiment is a white with a slight blue tint, and a thinner than this gives a blue tone shifted to the shorter wavelength side, while a thicker one gives a red tone shifted to the longer wavelength side. Become. Therefore,
The thickness to be sliced is appropriately adjusted and used according to the application.

FIGS. 2 and 3 show the light emitting element chip 2 described above.
1 illustrates a wavelength conversion type light-emitting diode 20 configured by using No. 1 and a mounting form on a motherboard. The light-emitting diode 20 has a pair of external connection electrodes 3 on an upper surface of a circuit board 31 made of a substantially rectangular glass epoxy.
2, 33 (cathode, anode) are formed in a pattern, and the lower electrodes 32a, 33a formed integrally therewith are fixed to printed wirings 37, 38 on a motherboard 36 by solder 39 to perform surface mounting.

The light emitting element chip 21 includes a circuit board 31
The external connection electrodes 32 and 33 on the circuit board side and the n-type electrode 25 and the p-type electrode 26 on the light-emitting layer 27 side are heat-pressed through the bumps 40 and electrically connected. Connected. The material of the bump 40 is gold (Au).
The light emitting element chip 21 connected to the circuit board 31 in this manner is sealed by a colorless and transparent resin sealing body 34, and is protected from mechanical stress. This resin sealing body 3
Reference numeral 4 is formed so as to completely cover the entire light emitting element chip 21 while leaving a part of the side surfaces and upper surfaces of the electrodes 32 and 33.

In the light emitting diode 20 having the above-described structure, the blue light emitted from the light emitting element chip 21 having the light emitting layer 27 and the element substrate 22 excites the fluorescent particles contained in the upper wavelength conversion substrate 28 to produce a long wavelength light. Wavelength is converted to a fluorescent color, which is visible light of Then, the motherboard 3 is mixed with the original blue light and passes through the colorless and transparent resin sealing body 34.
Thus, white light emission 30 for irradiating the upper surface side of 6 is obtained.

Next, the manufacturing process of the surface-mounted light-emitting diode 20 having the above configuration will be described with reference to a series of process diagrams of FIG. 4 and individual process diagrams of FIGS. As shown in FIG. 4, the surface-mounted type light emitting diode 20 is formed as an integrated circuit board (step 1), flip-chip mounted (step 2),
It is manufactured through a series of manufacturing steps of wavelength conversion substrate formation (step 3), resin molding / curing (step 4), and cutting / division (step 5). Next, individual manufacturing steps will be described. FIG.
Shows a manufacturing process (process 1) of the collective circuit board 51. Electrode patterns 52 and 53 serving as anode and cathode electrodes and a through hole 54 are formed on one integrated circuit board 51. The collective circuit board 51 is a board made of a resin such as glass epoxy and has a size of about 80 mm × 60 m.
It is 0.3 mm thick with m squares. The through hole 54
Is formed in a long groove shape, and on the surface of the collective circuit board 51,
They are provided in parallel at regular intervals. Electrode pattern 5
2 and 53 are arranged in a matrix so as to be branched from the through hole 54, and one bump 40a is provided on one anode-side electrode pattern 52 and three bumps 40a are provided on the other cathode-side electrode pattern 53. The bumps 40b to 40d are respectively formed. The bumps 40b to 40d
Among them, 40b is a dummy bump for electrical connection with the electrode pattern 53 on the cathode side, and the remaining bumps 40c and 40d are also electrically connected to the electrodes. These through holes 54 and electrode patterns 52 and 53 are formed by etching or vapor deposition. The number of the pair of electrode patterns 52 and 53 provided on one integrated circuit board 51 is about 800 at the maximum.

FIG. 6 shows the formed electrode patterns 52,
This shows a step (step 2) of flip-chip mounting the element substrate 22 provided with the gallium nitride-based compound semiconductor light emitting layer 27 on the 53 bumps 40a to 40d.
The bumps 40a to 40d are made of gold (Au) as a raw material. The bumps 40a to 40d are pressed by ultrasonic waves from the upper surface side of the element substrate 22 while being heated, thereby forming the electrode patterns 52, 53.
And the p-type electrode 26 and the n-type electrode 25 of the light emitting layer 27 are electrically connected. 6 is a view of the joint between the pair of electrode patterns 52 and 53 and the lower surface side of the light emitting layer 27 as viewed from above the integrated circuit board 51. On the lower surface of the light emitting layer 27, there are a small square p-type electrode pad 41 and an L-shaped n-type electrode pad 42 as shown in FIG. An n-type electrode 25 is formed. The p-type electrode 26 is bonded to the anode-side electrode pattern 52 via the bump 40a, and the n-type electrode 25 is connected to the cathode-side electrode pattern 53.
Are connected via the bumps 40b, 40c, and 40d to achieve conduction. As described above, the bumps 40c, 4c
0d is a dummy bump for bonding.

Next, as shown in FIG. 7, a transparent adhesive is applied to the upper surface of the gallium nitride-based compound semiconductor device substrate 22 mounted on the flip chip, and then the wavelength conversion substrate 28 previously sliced to a predetermined thickness. (Step 3). By this step, the light emitting element chip 21
Is completed.

Subsequently, as shown in FIG. 8, a mold 55 for masking only a portion along the through hole 54 of the collective circuit board 51 on which the light emitting element chips 21 are formed is mounted. Then, a colorless and transparent resin 56 is filled over the entire surface of the collective circuit board 51 so as to seal the entire light emitting element chip 21 in the mounted mold 55. Thereafter, curing is performed to cure the filled resin 56 by light irradiation or heat treatment (step 4).

Finally, as shown in FIG. 9, the mold 55 is removed from the cured and cured resin 56. Then, the Y axis (Y1, Y2,
.. Yn), the collective circuit board 51 is cut for each single light emitting diode (step 5). Through such a series of steps, each light emitting diode 20 as shown in FIG. 2 is completed. In the case of mounting, as shown in FIG. 3, they are mounted on printed wirings 37 and 38 formed on a motherboard 36 and connected by solder 39.

According to the light emitting diode according to the above-described embodiment, it is optimal in terms of optical characteristics as a flip-chip mounting type surface mounting light emitting diode using bumps.
The structure is also excellent in mass production. On the other hand, the light-emitting element chip 21 and the circuit board 3
The light emitting diode according to the present invention can be applied to a case where the pair of electrode patterns 52 and 53 on the first electrode are connected by a bonding wire.

[0027]

As described above, according to the light emitting diode of the present invention, the zinc selenide-based compound semiconductor forming the wavelength conversion substrate is directly bonded and fixed to the light emitting surface of the element substrate. Uniform white light emission can be obtained without variations in light emission luminance and uneven color tone as compared with a wavelength conversion substrate formed by dispersing materials.

Further, since the formation of the wavelength conversion substrate is performed only by bonding the sliced zinc selenide-based compound semiconductor with a transparent adhesive, the manufacturing steps and cost of the light emitting diode can be simplified.

Further, by appropriately adjusting the thickness of the zinc selenide-based compound semiconductor to be sliced, it becomes possible to manufacture light emitting diodes having various brightness and color tones.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a light emitting element chip constituting a surface mounted light emitting diode according to the present invention.

FIG. 2 is a perspective view of the surface mounted light emitting diode.

FIG. 3 is a cross-sectional view when the surface-mount type light emitting diode is mounted on a motherboard.

FIG. 4 is a process chart showing a series of manufacturing steps of the surface-mounted light emitting diode.

FIG. 5 is a process chart of forming an electrode pattern when manufacturing the surface-mounted light-emitting diode on a collective circuit board.

FIG. 6 is a process chart for mounting an element substrate having a light emitting layer on the collective circuit substrate.

FIG. 7 is a process chart for bonding a wavelength conversion substrate on the mounted element substrate.

FIG. 8 is a process diagram in which a light emitting element chip on the collective circuit board is sealed with a resin sealing body and cured.

FIG. 9 is a process diagram of dividing the collective circuit board sealed with the resin sealing body along a cutting line in the Y direction.

FIG. 10 is a cross-sectional view showing an example of a conventional wavelength conversion type light emitting diode.

[Explanation of symbols]

 Reference Signs List 21 light-emitting element chip 22 element substrate 23 n-type semiconductor 24 p-type semiconductor 25 n-type electrode 26 p-type electrode 27 light-emitting layer 28 wavelength conversion substrate 31 circuit board 32, 33 external connection electrode

Claims (3)

[Claims] 1. An element substrate comprising sapphire glass,
A gallium nitride-based compound semiconductor having a light-emitting layer and an electrode formed on the surface thereof, comprising a light-emitting device chip in which a wavelength conversion substrate formed of a zinc selenide-based compound semiconductor is bonded and fixed to the back surface of the device substrate. A surface-mount type light emitting diode characterized by the following. 2. The light emitting element chip is mounted on a circuit board with the light emitting element chip turned upside down, electrodes of the light emitting element chip are connected to the circuit board via bumps, and the light emitting element chip is mounted on a circuit board surface with a resin. 2. A sealed structure according to claim 1.
A surface-mounted light emitting diode as described. 3. A process of forming a long groove-shaped through-hole in a collective circuit board and an electrode pattern connected to the through-hole in a matrix, wherein a light-emitting layer and an electrode are formed on a surface of an element substrate made of sapphire glass. Placing the gallium nitride-based compound semiconductor upside down on the electrode pattern and electrically connecting the electrode and the electrode pattern via bumps; and gallium nitride placed on the collective circuit board. Forming a light-emitting element chip assembly by bonding and fixing a wavelength conversion substrate formed of a zinc selenide-based compound semiconductor on the upper surface of an element substrate of a system compound semiconductor; and disposing a mold on the assembly circuit substrate, Filling the mold with a resin to seal the light emitting element chip assembly; and, after curing the resin, dividing the collective circuit board into single light emitting diodes. Method for producing a surface-mount-type light-emitting diode, characterized in that a step.