JP2004288827A - Led lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the height on the light-emitting surface side to half or less of a present condition in an LED lamp. <P>SOLUTION: In the LED lamp 1, mutually insulated electrode plates 3a, 3b, 3c, 3d, 4 and 8 are formed on the bottom surface of the opening section 2a of a package 2 composed of alumina, a wire 5 is bonded to the electrode plates 3a and 8 from electrodes on the top faces of red light-emitting elements R1 and R2, a conductive wire is connected to the electrode plate 3a on the right side through the package 2 from the electrode plate 3a on the left side, and the elements R1 and R2 are connected in series. The two electrodes directed towards undersides are processsed by flip-chip bonding to the electrode plates 3b, 3d and 3c and the electrode plates 4 through gold bumps respectively in blue light-emitting elements B1 and B2 and a green light-emitting element G, and the height on the light-emitting surface side can be shortened to half or less (1 mm) of the present condition (2.15 mm) by detaining a wire bonding in the irreducible minimum of a demand in this manner and burying the electrode plates in the package 2 without a leading-out as leads. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light-emitting diode lamp in which a plurality of light-emitting elements and an electrode plate and a wire for electrically connecting the light-emitting elements are housed in a package made of ceramics or the like and sealed with a material such as a light-transmitting transparent epoxy resin. (Hereinafter, also abbreviated as “LED lamp”).
[0002]
In this specification, the LED chip itself is referred to as a “light emitting element”, and the entire light emitting device on which a plurality of LED chips are mounted is referred to as a “light emitting diode lamp” or an “LED lamp”.
[0003]
[Prior art]
Conventionally, a plurality of leads made of metal are arranged in a synthetic resin package formed by injection molding, and a plurality of light emitting elements are mounted on one of the leads, and are electrically connected to other leads by wire bonding. An SMD package type LED lamp, which is entirely sealed with a transparent epoxy resin or the like, is used as a backlight light source or the like. FIG. 5 shows an example of such an LED lamp. FIG. 5A is a front view showing a configuration of a conventional LED lamp, and FIG. 5B is a cross-sectional view showing a YY cross section of FIG.
[0004]
As shown in FIG. 5A, the LED lamp 11 has a single metal lead 13 extending from the left end to the right end of the opening 12a on the upper half of the opening 12a of the package 12 made of synthetic resin. It is sandwiched between packages 12. A total of five light emitting elements, two red light emitting elements R1 and R2, two blue light emitting elements B1 and B2, and one green light emitting element G, are arranged on the lead 13 at a narrow interval in a row. Mounted.
[0005]
On the other hand, in the lower half of the opening 12a, there is a projecting portion of the lead 13 at a substantially central portion, and five leads 14a, 14b, 14c, 14d, 14e are sandwiched in the package 12 at an interval from the lead 13. ing. , 14e and the package 12 are integrally formed by setting the leads 13, 14a,..., 14e in an injection mold of the package 12 and insert-molding the package 12. ing.
[0006]
In the LED lamp 11, the leads 14a,..., 14e drawn out below the package 12 are bent forward or backward along the lower surface of the package 12. Specifically, the leads 14b, 14d are bent forward, and the leads 14a, 14c, 14e are bent backward. The bent surface is soldered on the mounting board 18. Thus, the LED lamp 11 is mounted on the mounting board 18 by the solder 17.
[0007]
[Problems to be solved by the invention]
However, in recent years, the demand for LED lamps for backlighting liquid crystal display screens of mobile phones, which are rapidly increasing in demand, particularly for field-sequential LED lamps, is required to further reduce the thickness of mobile phones. The height of the lamp on the light emitting surface side is also required to be reduced to a half or less of the current height. On the other hand, as in the LED lamp 11 shown in FIG. 5, five light emitting elements are die-bonded to the upper half of the light emitting surface (opening 12a), and leads 14a,. In the method of wire bonding, it is hardly possible to further reduce the thickness of the light emitting surface.
[0008]
Therefore, according to the present invention, the height on the light emitting surface side can be reduced to half or less of the current state by minimizing the wire bonding and embedding the electrode plate in the package instead of drawing it out as a lead. It is an object to provide an LED lamp.
[0009]
[Means for Solving the Problems]
The LED lamp according to claim 1, wherein a plurality of light emitting elements are electrically connected to a plurality of electrode plates in a package, and the plurality of light emitting elements are sealed with a light transmitting material. Of the light emitting elements, the red light emitting element is die-bonded and wire-bonded along the longitudinal direction of the package, the green light emitting element and the blue light emitting element are flip-chip connected with the electrodes facing down, and the electrode plate connecting these Is embedded in the package and pulled out from the back of the light emitting surface.
[0010]
In this way, the green light emitting element and the blue light emitting element are flip-chip connected to the electrode plate via gold bumps or the like with the two electrodes facing down without die bonding. The red light-emitting element is die-bonded and wire-bonded from the upper electrode. However, instead of providing an electrode plate below the light-emitting surface as in the conventional LED lamp 11, a plurality of light-emitting elements are arranged in a line. An electrode plate is provided on the line, and wire bonding is performed along the longitudinal direction of the package. These electrode plates are embedded in a package, pulled out to the back side, and soldered so as to be connected to a power supply.
[0011]
Accordingly, if the space in the vertical direction of the light emitting surface (opening) is not only the size of the plurality of light emitting elements but also the electrode plates for electrically connecting the plurality of light emitting elements have a margin that does not conflict with each other. This is good, and the space in the lower half of the conventional LED lamp 11 becomes unnecessary.
[0012]
In this way, by minimizing wire bonding and embedding the electrode plate in the package instead of drawing it out as a lead, the height on the light emitting surface side can be reduced to less than half of the current level. Become a ramp.
[0013]
According to a second aspect of the present invention, in the LED lamp according to the first aspect, the red light emitting element includes two or more red light emitting elements and is connected in series every two light emitting elements.
[0014]
Since the standard voltage Vf of the red light emitting element is about half that of the green light emitting element and the blue light emitting element, two red light emitting elements are connected in series to one green light emitting element and one blue light emitting element. If these are connected in parallel, the voltages to be loaded become substantially equal, so that each light emitting element can emit light stably.
[0015]
In this manner, the height of the light emitting surface side can be reduced to half or less of the current level, and the LED lamp can stably emit light from each light emitting element at a voltage close to the standard voltage Vf.
[0016]
According to a third aspect of the present invention, in the LED lamp according to the first or second aspect, the package is made of a ceramic material having good heat conductivity.
[0017]
Here, as a ceramic material having good thermal conductivity, aluminum nitride (AlN), alumina (Al ₂ O ₃ ), and the like are given. By using such a ceramic material having good thermal conductivity as a package material, heat radiation is much improved as compared with a conventional synthetic resin package 12 such as an LED lamp 11, and even if the lamp is continuously lit for a long time. The light emitting characteristics of each light emitting element do not deteriorate.
[0018]
In this way, the height of the light-emitting surface side can be reduced to half or less of the current level, and an LED lamp that can stably emit light from each light-emitting element for a long time is obtained.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1A is a plan view showing a configuration of an LED lamp according to an embodiment of the present invention, FIG. 1B is a side view, and FIG. 1C is a cross-sectional view showing a XX section of FIG. FIG. 2 is a bottom view showing the configuration of the LED lamp according to the embodiment of the present invention. FIG. 3 is a circuit diagram showing a circuit configuration of the LED lamp according to the embodiment of the present invention. FIG. 4 is an exploded perspective view showing an example of a configuration of an LCD (liquid crystal display screen) to which the LED lamp according to the embodiment of the present invention is applied.
[0020]
As shown in FIG. 1A, this LED lamp 1 has electrode plates 3a, 3b, 3c, 3d, 4 that are insulated from each other on the bottom surface of an opening 2a of a package 2 made of alumina (Al ₂ O ₃ ). , 8 are provided, and a part of each penetrates to the bottom surface (back surface) of the package 2. At both ends, red light emitting elements R1 and R2 are die-bonded on the electrode plates 4 and 3a, respectively, and wires 5 are bonded to the left end electrode plate 3a from the electrodes on the upper surface of the red light emitting element R1. A wire 5 is bonded to an electrode plate 8 from an electrode on the upper surface of the red light emitting element R2. Further, from the left end electrode plate 3a, a conductive line (not shown) passes through the package 2 and is connected to the right electrode plate 3a, whereby the red light emitting elements R1 and R2 are connected in series.
[0021]
The blue light emitting element B1 has two electrodes facing the lower surface flip-chip connected to the electrode plate 3b and the electrode plate 4 via gold bumps, respectively. The blue light emitting element B2 has two electrodes facing the lower surface each having a gold bump. Similarly, the green light-emitting element G is flip-chip connected to the electrode plate 3c and the electrode plate 4 via gold bumps by the two electrodes facing the lower surface, respectively. Have been. Further, this alumina package 2 is obtained by cutting a through-hole board with a dicer, and gold platings 4 and 8 each having a shape close to a quarter circle are applied to the four corners. 2), it is connected to the bottom surface as shown in FIG.
[0022]
As shown in FIG. 1C, the opening 2a of the alumina package 2 is dug to about half the thickness of the package 2, and an electrode plate fixed to the bottom of the opening 2a. 3a, 3b, 3c, 3d, 4, 8, the light emitting elements R1, R2, B1, B2, G, and the two wires 5 are connected to a transparent epoxy resin 6 as a light transmissive material filled in the opening 2a. Is sealed by. The surface 6a of the transparent epoxy resin 6 has a slightly concave surface due to shrinkage during heating and curing, but if this shrinkage is taken into account and made flat during heating and curing, it can be used as a backlight. It is more preferable because the light guide plate can be brought into close contact with the light guide plate and the reflection loss is eliminated.
[0023]
Next, the bottom surface of the LED lamp 1 will be described with reference to FIG. As shown in FIG. 2, the bottom surface of the LED lamp 1 is provided with four gold plating patterns for soldering, and these gold plating patterns are provided on the electrode plate provided on the bottom surface of the opening 2a as described above. A part of 3a, 3b, 3c, 3d, 4, 8 is electrically connected to a part penetrating to the bottom of the package 2. Therefore, by electrically connecting these gold-plated patterns to a power source, power is supplied to the light emitting elements R1, R2, B1, B2, and G connected to the electrode plates 3a, 3b, 3c, 3d, 4, and 8. can do.
[0024]
Next, a circuit configuration of each light emitting element R1, R2, B1, B2, G will be described with reference to FIG. As shown in FIG. 3, the electric circuit of the LED lamp 1 is an anode common circuit having the electrode plate 4 as an anode terminal. Further, the two red light emitting elements R1 and R2 are connected in series. Since the standard voltage Vf of the red light emitting elements R1 and R2 is about half of that of the green light emitting element G and the blue light emitting elements B1 and B2, each of the green light emitting element G and the blue light emitting element B1 and B2 has If two red light emitting elements R1 and R2 are connected in series and connected in parallel, the voltages to be applied become almost equal, so that the light emitting elements R1, R2, B1, B2 and G emit light stably. be able to.
[0025]
Next, as an application example of the LED lamp 1 configured as described above, a configuration when the LED lamp 1 is used as a backlight of a liquid crystal display screen (LCD) of a mobile phone will be described with reference to FIG. As shown in FIG. 4, in this case, two LED lamps 1 are used, and the light-emitting surface is attached to the end face of the light guide plate 23 in close contact. The height of the light emitting surface side of the LED lamp 1 is about 1 mm as shown in FIG. 1A, but the height of the light emitting surface (opening 2a) itself is about 0.7 mm. Has a thickness of about 0.7 mm. Nevertheless, the end face is tapered to further reduce the thickness of the light guide plate 23 body.
[0026]
A reflection sheet 24 is provided below the light guide plate 23, and functions to reflect the LED light leaking downward from the light guide plate 23 and collect the LED light toward the LCD 20 side. On the other hand, a diffusion sheet 22 is stacked on the light guide plate 23, and two BEF sheets 21 are further stacked thereon. Each of these sheets 21 and 22 functions to improve the uniformity of the LED light emitted upward from the light guide plate 23 and increase the brightness of the liquid crystal display screen 20.
[0027]
By storing these plate members and sheet members in the case 25, they are precisely aligned and the electrical connection of the two LED lamps 1 to an external power supply is also ensured. In this manner, the height of the light emitting surface side is reduced from about 2.15 mm of the conventional LED lamp 11 to about 1 mm, which is half or less at a stretch, so that the liquid crystal display screen 20 of the mobile phone which is required to be further thinned. This LED lamp can be used as a full-color LED lamp for a white backlight and a field sequential system capable of displaying a color even on a black-and-white liquid crystal display screen.
[0028]
In the LED 1 of the present embodiment, since two blue light emitting elements B1 and B2 and one green light emitting element G are used, blueish white light is emitted as a whole. Further, the blue light emitting element has higher luminous efficiency than the green light emitting element, which leads to lower power consumption. On the other hand, when greenish white light is required, two green light emitting elements G1 and G2 and one blue light emitting element B may be used.
[0029]
In this embodiment, an example in which three primary light colors of red, green, and blue are used to form a white LED lamp or a field sequential LED lamp has been described. When used as a small LED lamp, light emitting elements of other colors may be used, light emitting elements of four or more colors may be used, or a plurality of light emitting elements of two or one color may be used. .
[0030]
Further, in the present embodiment, an example in which alumina (Al ₂ O ₃ ), which is a kind of ceramic material, is used as a package material has been described, but various ceramic materials such as aluminum nitride (AlN) and the like are used. Materials can be used.
[0031]
Furthermore, in the present embodiment, an example in which a transparent epoxy resin is used as a light-transmitting material as a sealing material has been described, but in addition to the transparent silicon resin, fluidity before curing, filling property, Any light-transmitting material may be used as long as it satisfies conditions such as transparency and strength after curing.
[0032]
The configuration, shape, quantity, material, size, connection relationship, and the like of other portions of the LED lamp are not limited to the present embodiment.
[0033]
【The invention's effect】
As described above, the LED lamp according to the first aspect of the present invention is an LED lamp in which a plurality of light emitting elements are electrically connected to a plurality of electrode plates in a package and sealed with a light transmitting material. A red light emitting element among the plurality of light emitting elements is die-bonded and wire-bonded along a longitudinal direction of the package, and a green light emitting element and a blue light emitting element are flip-chip connected with their electrodes facing down. The electrode plate to which is connected is embedded in the package and drawn out on the back surface of the light emitting surface.
[0034]
In this way, the green light emitting element and the blue light emitting element are flip-chip connected to the electrode plate via gold bumps or the like with the two electrodes facing down without die bonding. The red light-emitting element is die-bonded and wire-bonded from the upper electrode. However, instead of providing an electrode plate below the light-emitting surface as in the conventional LED lamp 11, a plurality of light-emitting elements are arranged in a line. An electrode plate is provided on the line, and wire bonding is performed along the longitudinal direction of the package. These electrode plates are embedded in a package, pulled out to the back side, and soldered so as to be connected to a power supply.
[0035]
Accordingly, if the space in the vertical direction of the light emitting surface (opening) is not only the size of the plurality of light emitting elements but also the electrode plates for electrically connecting the plurality of light emitting elements have a margin that does not conflict with each other. This is good, and the space in the lower half of the conventional LED lamp 11 becomes unnecessary.
[0036]
In this way, by minimizing wire bonding and embedding the electrode plate in the package instead of drawing it out as a lead, the height on the light emitting surface side can be reduced to less than half of the current level. Become a ramp.
[0037]
According to a second aspect of the present invention, in the LED lamp according to the first aspect, the red light emitting element includes two or more red light emitting elements and is connected in series every two light emitting elements.
[0038]
Since the standard voltage Vf of the red light emitting element is about half that of the green light emitting element and the blue light emitting element, two red light emitting elements are connected in series to one green light emitting element and one blue light emitting element. If these are connected in parallel, the voltages to be loaded become substantially equal, so that each light emitting element can emit light stably.
[0039]
In this manner, the height of the light emitting surface side can be reduced to half or less of the current level, and the LED lamp can stably emit light from each light emitting element at a voltage close to the standard voltage Vf.
[0040]
According to a third aspect of the present invention, in the LED lamp according to the first or second aspect, the package is made of a ceramic material having good heat conductivity.
[0041]
Here, as a ceramic material having good thermal conductivity, aluminum nitride (AlN), alumina (Al ₂ O ₃ ), and the like are given. By using such a ceramic material having good thermal conductivity as a package material, heat radiation is much improved as compared with a conventional synthetic resin package 12 such as an LED lamp 11, and even if the lamp is continuously lit for a long time. The light emitting characteristics of each light emitting element do not deteriorate.
[0042]
In this way, the height of the light-emitting surface side can be reduced to half or less of the current level, and an LED lamp that can stably emit light from each light-emitting element for a long time is obtained.
[Brief description of the drawings]
FIG. 1A is a plan view showing a configuration of an LED lamp according to an embodiment of the present invention, FIG. 1B is a side view, and FIG. 1C is a cross-sectional view showing an XX section of FIG. It is.
FIG. 2 is a bottom view showing the configuration of the LED lamp according to the embodiment of the present invention.
FIG. 3 is a circuit diagram showing a circuit configuration of the LED lamp according to the embodiment of the present invention.
FIG. 4 is an exploded perspective view showing a configuration of an example of an LCD (liquid crystal display screen) to which the LED lamp according to the embodiment of the present invention is applied.
5A is a front view showing a configuration of a conventional LED lamp, and FIG. 5B is a cross-sectional view showing a YY cross section of FIG. 5A.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 LED lamp 2 Package 3a, 3b, 3c, 3d, 4,8 Electrode plate 5 Wire 6 Sealing resin 20 LCD
23 light guide plate 24 reflection sheet B1, B2 blue light emitting element G green light emitting element R1, R2 red light emitting element

Claims (3)

In an LED lamp in which a plurality of light emitting elements are electrically connected to a plurality of electrode plates in a package and sealed with a light transmitting material,
Of the plurality of light emitting devices, the red light emitting device is die-bonded and wire-bonded along the longitudinal direction of the package, and the green light emitting device and the blue light emitting device are flip-chip connected with the electrodes facing down, and these are connected. The above-mentioned electrode plate is embedded in the above-mentioned package and drawn out to the back of the light-emitting surface. 2. The LED lamp according to claim 1, wherein the red light-emitting elements include two or more light-emitting elements and are connected in series every two light-emitting elements. The LED lamp according to claim 1, wherein the package is made of a ceramic material having good thermal conductivity.

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