JP2000022222A - Light emitting diode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a uniform wavelength conversion and prevent a color unevenness caused by a difference between conversion efficiencies, by a method wherein a wavelength conversion element in which a thickness and a density of a wavelength conversion substance have previously been set to be a desired value is provided. SOLUTION: A wavelength conversion element 4 is provided with a wavelength conversion element layer 4a, in which uniform mixture of a wavelength conversion substance with a resin binder holding the wavelength conversion substance is coated and cured on a sheet-like base body film 4b. And, it is arranged in a reflection horn 2 so that the wavelength conversion element layer 4a is brought into contact with a translucent substrate 3a of a LED chip 3. The wavelength conversion element 4 is not predipped in the reflection horn 2 to cure, but the wavelength conversion substance is formed in a layered manner. Accordingly, it is possible to control a thickness of the wavelength conversion substance layer and enhance uniformity of a wavelength conversion efficiency and an efficiency.

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 (hereinafter referred to as "light emitting diode").
More specifically, the present invention relates to an LE using a wavelength conversion substance for color conversion of light emitted from a light emitting diode chip (hereinafter, referred to as an LED chip).
It relates to D.

[0002]

2. Description of the Related Art Japanese Patent Laid-Open No. 7-99345 is known as an example of a conventional LED using such a wavelength converting substance. As shown in FIG. 6, an LED chip 93 is placed in a reflection horn 92 formed on a lead frame 91. One electrode of the LED chip 93 is connected to the reflection horn 92, and the other electrode is connected to a lead frame 94 by a wire 95. Bonding connection. Reflective horn 9
A first resin 96 containing a conversion substance such as a fluorescent substance that converts the emission wavelength of the LED chip to another wavelength or a filter substance that absorbs a part of the emission wavelength is hardened by pre-dip in 2. Let me. After that, the second resin 97 having a lower refractive index than that of the first resin and being close to the refractive index of air is cured so as to cover them, thereby forming the LED 90.

[0003]

However, in the above-mentioned conventional LED 90, the reflection horn is formed so as to cover the LED chip 93 connected to the first resin 96 containing the wavelength conversion material such as a fluorescent material by wire bonding. Since the first resin 96 is formed by hardening after pre-dip in the inside 92, the first resin 96 has a non-uniform thickness covering a complicated convex shape. Also, when pre-dipping the wavelength converting substance, the specific gravity of the wavelength converting substance is higher than the specific gravity of the resin, so that the wavelength converting substance settles before curing, and the distribution of the wavelength converting substance after application becomes uneven. easy. for that reason,
The light emitted from the LED chip is further non-uniformly converted in wavelength in the first resin 96 formed in various thicknesses. Therefore, there is a problem that the conversion efficiency is reduced, and the conversion efficiency varies depending on the position. As a result, there is a problem that the LED causes color unevenness.

[0004]

According to the present invention, as a specific means for solving the above-mentioned conventional problems, there are provided a lead frame having a reflective horn, a light emitting diode chip mounted in the reflective horn, A wavelength conversion element that converts the wavelength of light emitted from the light-emitting diode chip, and a light-emitting diode in which these are covered with a light-transmitting material and sealed, and in the reflection horn, the light-transmitting substrate is provided. At least one or more light emitting diode chips are disposed on the reflection horn upper surface side and arranged so that the electrodes are electrically connected to the lead frame on the reflection horn bottom surface side. Including a substance and a translucent substrate holding the substance, the density is adjusted in advance to a predetermined density and a thickness is formed in a layered form, and the reflection horn is formed with an engaging claw, At the top of the photodiode chip position, is intended to solve the problems described above by the wavelength conversion element by engaging claw is to provide a light-emitting diode is fixed.

[0005]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 shows a light emitting diode 10 according to the present invention. Reflection horns 2 and 2 are formed on a pair of lead frames 1 and 1, respectively, and LED
The chip 3 is disposed such that the bottom surfaces 2a and 2b of the reflection horns 2 and 2 and the electrodes 3c and 3d provided on the chip are connected to each other, and the light-transmitting substrate 3a is positioned above the reflection horn 2. Are located.

Further, a wavelength conversion element 4 is disposed above the LED chip 3 so as to be in contact with the translucent substrate 3a of the chip 3. The wavelength conversion element 4 is provided with a wavelength conversion element layer 4a formed by uniformly coating a wavelength conversion substance and a resin binder holding the wavelength conversion substance on a sheet-like base film 4b. The wavelength conversion element layer 4 a is disposed in the reflection horn 2 so as to be in contact with the light transmitting substrate 3 a of the LED chip 3. An engagement claw 2c for fixing the wavelength conversion element 4 is formed substantially all around the inner peripheral edge of the reflection frame of the reflection horn 2, and a portion of the base film 4b of the wavelength conversion element 4 is engaged with the engagement claw 2c. It is to be surely fixed by pressing down.

As the LED chip 3, for example, a GaN-based LED that emits blue and / or ultraviolet light (λ = 370 to 500 nm) can be used. A GaN-based light-emitting layer 3b is formed on a light-transmitting substrate 3a made of sapphire or the like that transmits light at the emission wavelength, and a p-electrode 3c and an n-electrode 3d are formed on the same surface side. Further, in this embodiment, the wire bonding connection is not performed as in the conventional example, but the electrode of the LED chip 3 and the lead frame 1 are connected.
No wire is used for the electrical connection with the reflection horn 2 of FIG. That is, a bonding bump is formed on each of the pair of electrodes of the p-electrode 3c and the n-electrode 3d, and the reflection horn bottom surfaces 2 of the pair of lead frames 1, 1 are formed via the bumps.
a and 2b are electrically connected.

Next, after the wavelength conversion elements 4 are fixed, the outer circumferences of the lead frames 1 and 1 are covered with a light-transmitting sealing material 5 molded and hardened with a light-transmitting epoxy resin or the like so as to cover them. An LED 10 is obtained as a cover.
The wavelength conversion element 4 has the wavelength conversion element layer 4a on the LED chip 3 side so that a large amount of the wavelength conversion substance exists on the side in contact with the LED chip 3, and covers the entire surface of the reflection horn 2 as shown in the drawing. Is preferable in terms of conversion efficiency and uniformity.

As described above, the wavelength conversion element 4 is not pre-dip and cured in the reflection horn 2, but is formed in a layered form of the wavelength conversion substance. Therefore, the thickness of the wavelength conversion substance layer is controlled. Thus, the wavelength conversion efficiency can be made uniform and the efficiency can be improved. In addition, since uniform wavelength conversion is possible, color unevenness due to a difference in conversion efficiency can be significantly reduced. Further, since the wavelength conversion element 4 is disposed right above the LED chip 3 and is fixed by the engagement claws 2c, the loss of light emitted from the LED chip, that is, light incident on the wavelength conversion element 4, is minimized. It can be fixed by pressing. Furthermore, by making the wavelength conversion element 4 large enough to cover substantially the entire surface of the reflection horn 2, it is possible to convert the wavelength of light emitted from the side surface of the LED chip 3 and to achieve more uniform light emission. It can be.

Here, the wavelength conversion element 4 will be further described. As described above, the wavelength conversion element 4 is formed by coating the wavelength conversion element layer 4a on the base film 4b as described above, but is not limited thereto. For example, it can be obtained by the following method.

FIGS. 2A to 2C show the wavelength conversion element 41.
FIG. 3 is a schematic diagram for describing a manufacturing method of (1) in the order of steps. The wavelength conversion substance 42 is dispersed in advance in a dispersion medium 43 made of a thermosetting resin and sufficiently stirred. Next, the pattern mask 45 in which the opening of the desired shape is formed and the support 46 are overlapped, a predetermined amount of the dispersion medium is poured into the opening, and the opening is allowed to stand for a certain time. After that, when the dispersion medium is cured and released from the pattern mask 45, the high-density wavelength conversion element layer 41a in which the wavelength conversion substance 42 is uniformly dispersed at high density due to the specific gravity difference, and the low-density or wavelength The wavelength conversion element 41 on which the low-density wavelength conversion element layer 41b in which the conversion substance is not dispersed is formed is obtained. The thickness of the high-density wavelength conversion element layer 41a and the low-density wavelength conversion element layer 41b and the density of the wavelength conversion substance are appropriately changed by the specific gravity and viscosity of the material to be used, the time during which the material is injected into the openings and left standing, the mixing ratio, and the like. Can be adjusted.

Specifically, 11.2 g of a ZnS-based phosphor having a specific gravity of 4.1 as the wavelength converting substance 42 is mixed with 100 g of a translucent epoxy resin having a specific gravity of 1.1, which is a dispersion medium 43, and is mixed with a magnetic stirrer. Stir at 500 rpm for 30 minutes. Next, a predetermined amount of this stirred suspension was poured into an opening having an outer shape of 2 mm and a depth of 1 mm of the pattern mask 45 by a dispenser 44, and was left for 30 minutes. As a result, the wavelength conversion substance 42 having a large specific gravity sinks to the lower part. In this state, heat treatment was performed to cure the epoxy resin 43, and the pattern mask 45 was separated from the support 46. Thus, a circular pellet-shaped wavelength conversion element 41 having an outer diameter of 2 mm could be obtained.

As the wavelength conversion material 42, for example, Zn
S: Cu, Au, Al phosphor, ZnS: Cu, Al phosphor, ZnS: Ag phosphor, ZnS: Ag + (Zn, C
d) Ag: Cu, A to ZnS such as S: Cu, Al phosphor, etc.
Blue, white, yellow-green, etc. using a material activated with various impurities such as l, Ga, Cl or the like, or a material activated with (Zn, Cd) S with impurities such as Cu, Al, Ag, etc. And various other phosphors, such as those that convert light in the ultraviolet to blue wavelengths, can be used alone or in combination of a plurality of phosphors. As the dispersion medium 43, a thermosetting resin such as an epoxy resin, a PET (polyethylene terephthalate), a silicon resin, a polycarbonate, an acrylic resin, or a UV-curable resin having a high transmittance with respect to an emission wavelength and a conversion wavelength. Various things can be used.

The wavelength conversion element is not limited to the one manufactured by the above-described manufacturing method, but may be any one in which a wavelength conversion material layer is applied or printed on a sheet-like translucent substrate as described above. After the wavelength conversion material layer is formed, the wavelength conversion material layer may be cut into a predetermined shape, or the low-density or low-density wavelength conversion element layer in which the wavelength conversion material is not dispersed, and the high-density wavelength conversion in which the wavelength conversion material is uniformly dispersed. The element layer may be laminated into a predetermined shape by injection molding or the like, or may be cut after molding.

Next, instead of the wavelength conversion element 4 of the LED 10 of the above-described embodiment, the wavelength conversion element 40 is
The operation and effect of using the LED 10 shown in FIG. The efficiency of wavelength conversion largely depends on the density and thickness of the wavelength conversion substance excited by the irradiation light from the LED chip. Compared with the case where the wavelength conversion element 4 in the above-described embodiment is used, the use of the wavelength conversion element 40 manufactured in the present embodiment allows the wavelength conversion substance to be more densely formed than in the case of the previous embodiment. The provided high-density wavelength conversion material layer 41a can be manufactured easily, uniformly, and efficiently. Therefore, the high-density wavelength conversion material layer 4
By providing 1a in close contact with the LED chip 3,
Loss when the light emitted from the LED chip 3 reaches the wavelength conversion material 42 can be further minimized.

Next, another embodiment will be described. In the above embodiment, the light-transmitting substrate 3 of the LED chip 3
a is provided on the side of the wavelength conversion element 4 so that the wavelength conversion element 4 is fixed so as to be in close contact with the substrate 3a. However, in this embodiment, as shown in FIG. It is fixed so as not to be in close contact with the LED chip 33 and to be sandwiched between the reflection frame steps 32d by the engagement claws 32c provided on the reflection horn. In addition, the LED chip 33 has the chip substrate 33 installed on the bottom surface of the reflection horn 32 formed on one lead frame 31, and a pair of electrodes formed on the top surface of the LED chip substrate 33, the bottom surface of the reflection horn 32 and the other end. The bottom surface of the reflection horn 32 formed on the lead frame is electrically connected to each other by a wire 35. The wavelength conversion element 34 is disposed such that the high-density wavelength conversion element layer 34a in which the wavelength conversion substance exists at high density is located on the LED chip 33 side, and the low-density wavelength conversion element layer 34b is located on the opposite side. .

Thus, the LED chip 33 is connected to the wire 35
When the connection is made with the LED chip 35
And the wavelength conversion element 34, it cannot be provided in close contact. Therefore, by providing a step 32d or the like on the reflection horn 32 and fixing the wavelength conversion element 34 by the step 32d and the engaging claw 32c, uniform wavelength conversion can be performed as in the previous embodiment. When a wire exists between the LED chip and the wavelength conversion element as in the present invention, light emitted from the light emitting layer is blocked by the wire and the electrode for providing the wire because of the presence of the wire, Since the distance between the two must be appropriately provided, the utilization efficiency of the radiated light extracted from the LED light emitting layer to the outside is deteriorated. Therefore, in the case of wire connection, it is preferable to make the distance between the LED chip and the wavelength conversion element as short as possible, and to reduce the area of the light-shielding substance such as the LED chip electrode and the wire existing therebetween.

Next, still another embodiment will be described. In the above embodiment, the reflection horns 2 and 2 are formed on both the lead frames 1 and 1. In the present embodiment, as shown in FIG.
1a, the reflection horn 12 is formed only on the reflection horn 12;
An opening 14 is provided on the bottom surface of. The other lead frame 11b is connected to the opening 1 of the reflection horn 12 described above.
No.4. The LED chip 13 is mounted on the bottom surface of the reflection horn 12, and a pair of electrodes of the LED chip 13 are formed by the reflection horn 12 and the opening 14 of the reflection horn 12.
Are electrically connected to the respective lead frames 11b. The wavelength conversion element is not shown for simplicity of the drawing. The wavelength of the light emitted from the LED chip 13 is changed as in the previous embodiment.

By doing so, the engaging claw 12c for fixing the wavelength conversion element can be provided on the entire circumference of the inner peripheral surface of the reflection frame of the reflection horn 12, and when the wavelength conversion element is fixed, the reflection horn and the wavelength can be reduced. It is possible to prevent any gap from being formed between the conversion element and the conversion element. Thereby, the light emitted from the LED chip 13 whose wavelength has not been converted does not leak from the gap, and the uniformity of the wavelength is further improved. The opening 14 is not limited to a circular shape as shown, but may be a U-shaped notch or the like.

FIG. 5 shows a main part of an LED 20 of still another embodiment. In this embodiment, two LED chips 25 and 26 having different emission wavelengths are used.
Lead frame 21a having opening and reflective horn 22
And lead frames 21b, 2 located at the opening of 21a.
It has three lead frames 1c, and two LED chips 25 and 26 are mounted on the bottom surface of the reflection horn 22. The electrodes 25a and 25b of the LED chip 25 are connected to the reflection horn 22 and the lead frame 21b without using wires. Electrode 26 of LED chip 26
a and 26b are also connected to the reflection horn 22 and the lead frame 21c, respectively, without using wires. A wavelength conversion element 24 is disposed on these LED chips 25 and 26 in close contact with each other, and a diffusion plate 27 is further disposed thereon. It is fixed by the dovetail 22c.

With such a configuration, the light emitted from one LED chip 25 is wavelength-converted by the wavelength conversion element 24 indirectly fixed by the engaging claw 22c, and the light is converted by the diffusion plate 27. Spread. The other LED
Since the emission light of the chip 26 has an emission wavelength that does not match the wavelength conversion element, it passes through without being subjected to wavelength conversion by the wavelength conversion element 24, and reaches the diffusion plate 27 directly fixed by the engagement claws 22c. ,Spread. In the diffusion plate 27, light from both LED chips is diffused and made uniform. Thus, the color of the LED 20 is determined by the wavelength conversion color of the wavelength conversion element 24 and the color of the emitted light from the LED chip that is not
Can be further arbitrarily changed as compared with the case where only the wavelength conversion element is used. In addition, although the example using two LED chips that emit different wavelengths has been described, two or more LED chips may be used, or LED chips that emit the same wavelength may be used. Furthermore,
Modifications such as providing a lens effect on the surface of the diffusion plate 27 or the wavelength conversion element so as to obtain a more uniform light-emitting LED 20 can be added.

In the embodiments described so far, a GaN-based LED chip that emits blue and / or ultraviolet light is used, and the emitted light excites a phosphor, which is a wavelength conversion substance, to convert the wavelength. However, the present invention is not limited to this.
ZnSe-based LED, GaAs-based LED (λ = 630-8
50 nm), a GaAlAs-based LED, a ZnO-based LED, or the like, and the wavelength converting material is not limited to the one that mainly converts the blue and / or ultraviolet light into another wavelength.
For example, NdP ₅ O ₁₄ , LiNdP ₄ O ₁₂ , Na ₅ N
d (WO ₄ ) ₄ , Al ₃ Nd (BO ₃ ) ₄ , Cs ₂ Na
The wavelength can be converted to a different wavelength by _NdCl6 , SrS, or the like, or various infrared-excited phosphors.
Further, wavelength conversion may be performed by using a specific wavelength absorbing material such as a dye instead of a phosphor as the wavelength converting material.

[0023]

As described above, according to the present invention,
Rather than dip the wavelength conversion material inside the reflection horn that has become convex by mounting the LED chip as in the past, the thickness and density of the wavelength conversion material are set to desired values in advance. By separately providing a wavelength conversion element,
Uniform wavelength conversion becomes possible, and color unevenness due to a difference in conversion efficiency can be significantly reduced. Further, in the present invention, since the wavelength conversion element is disposed directly above the LED chip, loss of light emitted from the LED chip, that is, attenuation of light incident on the wavelength conversion element can be further minimized. Furthermore, since the wavelength conversion element is fixed with the engagement claw so as to cover substantially the entire surface of the reflection horn, L
Wavelength conversion is possible for light emitted from the side surface of the ED chip, and more uniform light emission can be achieved. In addition, even if there is a slight gap between the wavelength conversion element and the reflection horn, the presence of the engaging claw at that location prevents leakage light in the LED front direction by the engaging claw. It has the effect.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view illustrating an LED of the present invention.

FIG. 2 is a schematic process diagram illustrating a method for manufacturing a wavelength conversion element of the present invention.

FIG. 3 is a schematic cross-sectional view illustrating another embodiment of the present invention.

FIG. 4 is a schematic perspective view illustrating another embodiment of the present invention.

FIG. 5 is a cross-sectional view of a principal part explaining still another embodiment of the present invention.

FIG. 6 is a schematic diagram illustrating a conventional LED.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead frame 2 Reflection horn 3 LED chip 4 Wavelength conversion element 4a Wavelength conversion element layer 4b Sheet-like film 5 Translucent sealing material 10 LED 11a, 11b Lead frame 12 Reflection horn 12c Engagement nail 13 LED chip 14 Opening 30 LED REFERENCE SIGNS LIST 31 lead frame 32 reflection horn 32 c engagement claw 32 d reflection frame step 33 substrate 34 wavelength conversion element 34 a high-density wavelength conversion element layer 34 b low-density wavelength conversion element layer 35 wire 90 LED 91 lead frame 92 reflection horn 93 LED chip 94 lead frame 95 wire 96 first resin 97 second resin

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 5F041 AA11 AA12 CA13 DA04 DA09 DA14 DA18 DA26 DA43 DA57 EE17 EE25

Claims (6)

[Claims] 1. A lead frame having a reflection horn, a light-emitting diode chip mounted in the reflection horn, and a wavelength conversion element for converting the wavelength of light emitted from the light-emitting diode chip. A light-emitting diode covered and sealed with a conductive material, wherein in the reflective horn, the translucent substrate is located on the reflective horn upper surface side, and the electrode is electrically connected to the lead frame on the reflective horn bottom surface side. At least one or more light emitting diode chips disposed so as to be connected to each other, wherein the wavelength conversion element includes a wavelength conversion substance and a translucent substrate holding the wavelength conversion substance, and has a predetermined density and thickness in advance. The reflection horn has an engagement claw formed thereon, and the engagement claw fixes the wavelength conversion element at a position above the light emitting diode chip. A light-emitting diode, comprising: 2. A lead frame having a reflection horn, a light-emitting diode chip mounted in the reflection horn, and a wavelength conversion element for converting the wavelength of light emitted from the light-emitting diode chip. A light-emitting diode covered and sealed with a conductive material, wherein at least one or more light-emitting diode chips are disposed in the reflection horn so as to be electrically connected, and the wavelength conversion element includes a wavelength conversion substance and A light-transmissive substance for holding the light-transmitting material, which is adjusted in advance to have a predetermined density and thickness to form a layer, and the reflection horn is formed with an engagement claw. A light-emitting diode, characterized in that a wavelength conversion element disposed on the substrate is fixed so as to be in close contact with the light-transmitting substrate of the light-emitting diode chip. 3. The wavelength conversion element has a wavelength conversion element layer containing a wavelength conversion substance at a relatively high density and a wavelength conversion element layer containing a wavelength conversion substance at a low density. The light-emitting diode according to claim 1, wherein the light-emitting diode is disposed so as to be located on an LED chip side. 4. The wavelength conversion element, after mixing and dispersing the wavelength conversion substance in the dispersion medium resin, flows into a mold, and the wavelength conversion substance is relatively dispersed due to a difference in specific gravity between the dispersion medium resin and the wavelength conversion substance. 4. The light-emitting diode according to claim 3, wherein the light-emitting diode is a wavelength conversion element that is cured by having a wavelength conversion element layer included in high density and a wavelength conversion element layer included in low density. 5. The light-emitting diode chip has two or more light-emitting diode chips emitting different emission wavelengths in the reflection horn, and a wavelength conversion element and a diffusion plate are sequentially stacked on the light-emitting diode chip. The light emitting diode according to any one of claims 1 to 4, wherein the light emitting diode is fixed by an engagement claw formed on the reflection horn. 6. The light-emitting diode chip has a light-emitting layer formed on a substrate having a light-transmitting wavelength, and an electrode formed on the same surface as the light-emitting layer. Is disposed in the reflection horn so that the substrate side of the reflection horn is above the reflection horn, and the electrode and the lead frame, which are the reflection horn bottom side, are electrically connected without using a wire. The light emitting diode according to claim 2.