KR20060041086A - Light emitting diode package employing a heat-sinking body and method of fabricating the same - Google Patents

Abstract

Disclosed is a light emitting diode package employing a heat dissipating body. The light emitting diode package includes a heat dissipation body having a depression on its top surface and a pair of lead frames. In addition, a package housing supports the heat dissipation body and the lead frame to be spaced apart from each other. Accordingly, heat generated in the LED die can be easily discharged, thereby improving the light emitting efficiency of the LED package.

Light Emitting Diode (LED), Heat Dissipation, Luminous Efficiency

Description

LIGHT EMITTING DIODE PACKAGE EMPLOYING A HEAT-SINKING BODY AND METHOD OF FABRICATING THE SAME}

1 is a cross-sectional view illustrating a conventional LED package employing a heat sink.

2 is a perspective view illustrating a light emitting diode package employing a heat dissipating body according to an exemplary embodiment of the present invention.

3 is a cross-sectional view of FIG. 2 for describing a light emitting diode package employing a heat dissipating body according to an exemplary embodiment of the present invention.

4 is a cross-sectional view of a heat dissipating body for describing a light emitting diode package according to another embodiment of the present invention.

5 is a cross-sectional view for describing a light emitting diode package employing the heat dissipating main body of FIG. 4.

<Description of reference numerals for main parts of the drawings>

31: package housing, 33: lead frame,

35: heat dissipation body, 37: light emitting diode die,

39: sealing agent, 41: reflective coating film

The present invention relates to a light emitting diode package, and more particularly, to a light emitting diode package that can improve the luminous efficiency by adopting a heat radiating body.

Recently, the use of light emitting diodes (LEDs) as light sources is increasing. In general, in order to be used for a purpose such as a light source for illumination, it is required that the light emitting diode have a luminous power of several tens of lumens or more. The light output of the light emitting diode is generally proportional to the input power. Therefore, a high light output can be obtained by increasing the power input to the light emitting diode. However, increasing the input power increases the junction temperature of the light emitting diode. The increase in junction temperature of the light emitting diode leads to a decrease in photometric efficiency, which indicates the degree to which the input energy is converted into visible light. Therefore, it is required to prevent an increase in the junction temperature of the light emitting diode according to the increase of the input power. To this end, a light emitting diode package is attached to a light emitting diode to radiate heat generated by the light emitting diode through the heat sink.

1 is a cross-sectional view illustrating a conventional LED package employing a heat sink.

Referring to FIG. 1, a conventional LED package includes an epoxy-based body 11 and a pair of lead frames 13. The main body 11 is formed using an injection molding technique after the lead frame 13 is provided. At this time, a depression is formed in the upper surface of the main body 11, and a through hole connected to the lower portion of the depression is formed. The depression is formed at a predetermined inclination angle, and serves as a reflecting surface for reflecting light emitted from the light emitting diode die 17 into a predetermined direction angle.

On the other hand, after the heat dissipation plate 15 having a protrusion at the center is individually manufactured, it is coupled to the main body 11. In this case, the protrusion is inserted into the through hole. The heat sink 15 is formed of a metal material having excellent heat transfer characteristics.

Thereafter, a light emitting diode die 17 is mounted on the upper surface of the protrusion. Subsequently, a pair of bonding wires are used to electrically connect the pair of lead frames 13 and the light emitting diode die 17. Subsequently, the encapsulant 17 is filled in the recessed portion of the main body 11 to protect the light emitting diode die 17. The encapsulant 17 may contain a phosphor and / or a diffusion agent.

The conventional light emitting diode package employs a heat sink 15, thereby rapidly dissipating heat emitted from the light emitting diode die 17 to the outside, thereby improving luminous efficiency. However, the heat dissipation characteristics of the heat sink 15 are limited by the size of the heat sink 15. Simply increasing the size of the heat sink 15 increases the size of the entire LED package. In addition, since the main body 11 is epoxy-based, the reflectance of light is relatively low. Therefore, the reflecting surface formed of the recessed sidewall of the main body 11 does not sufficiently reflect the light emitted from the light emitting diode die 17. Therefore, light loss by the reflective surface is generated.

 An object of the present invention is to provide a light emitting diode package that can improve heat dissipation characteristics while maintaining the size of the light emitting diode package.

Another object of the present invention is to provide a light emitting diode package capable of minimizing light loss by improving the reflectance of a reflective surface.

In order to achieve the above technical problem, the present invention provides a light emitting diode package adopting a heat dissipation body. The light emitting diode package includes a heat dissipation body having a depression on an upper surface thereof and a pair of lead frames. In addition, a package housing supports the heat dissipation body and the lead frame to be spaced apart from each other. By adopting a heat dissipation body made of a heat dissipation plate, it is possible to improve heat dissipation characteristics without increasing the size compared to a conventional LED package. In addition, since a reflective surface made of a heat dissipating body is formed on the sidewall of the depression, the light reflectance is improved to reduce light loss.

In addition, a reflective coating may be located on the bottom and sidewalls of the depression. The reflective coating further increases the reflectance of the light to minimize light loss at the reflective surface.

On the other hand, the package housing may be an epoxy formed using an insert molding technique. Accordingly, it is easy to manufacture a package housing for supporting the heat radiating body and the lead frame apart from each other.

The light emitting diode package may further include a light emitting diode die mounted on the bottom of the recess, and a pair of bonding wires electrically connecting the pair of lead frames and the light emitting diode die.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. In the drawings, lengths, thicknesses, and the like of layers and regions may be exaggerated for convenience. Like numbers refer to like elements throughout.

2 is a perspective view illustrating a light emitting diode package employing a heat dissipating body according to an exemplary embodiment of the present invention, and FIG. 3 is a cross-sectional view of FIG. 2.

2 and 3, the light emitting diode package adopts a heat dissipation body 35 having a depression thereon. The heat dissipation body 35 may be formed of aluminum (Al), copper (Cu), or an alloy thereof. In addition, the heat dissipation main body 35 having the depression may be formed using a press, and may be formed using a molding technique. Preferably, the bottom of the depression is a flat surface, and the side wall thereof is an inclined surface having a constant inclination angle with respect to the bottom surface. In this case, the inclination angle may be about 45 °. The inclined surface becomes a reflecting surface that reflects light emitted from the light emitting diode die.

Conventionally, the body 11 made of epoxy-based resin is used, but the present invention uses the heat dissipation body 35 made of a metal material having excellent heat dissipation characteristics. Therefore, the heat dissipation main body 35 relatively larger than the conventional heat dissipation plate 15 can be used, thereby improving heat dissipation characteristics. In addition, the heat dissipation body 35 made of a metal material having a high light reflectance, such as aluminum, has a high reflectance at the reflective surface, thereby reducing light loss as compared with the conventional plastic body 11.

As illustrated, the heat dissipation main body 35 may be circular, but is not limited thereto. The heat dissipation main body 35 may have various shapes such as square, hexagon, and octagon. On the other hand, the depression is preferably circular, as shown in order to obtain a symmetric light output pattern.

A conformal reflective coating layer 41 is formed on the sidewalls and the bottom of the depression. The reflective coating layer 41 increases the reflectance of the light to further reduce the light loss generated in the depression. The reflective coating layer 41 may be formed of, for example, aluminum (Al), silver (Ag), chromium (Cr), or an alloy thereof, using an electroplating technique. Although the reflective coating layer 41 is illustrated in the recessed inner wall of the drawing, the reflective coating layer 41 may be formed on the entire surface of the heat dissipation main body 31.

A pair of lead frames 33 are positioned above the heat dissipation body 31 to be spaced apart from the heat dissipation body 31. Each lead frame 33 includes an inner lead frame positioned adjacent to the depression of the heat dissipation body 31 and a lead terminal extending outward from the inner lead frame. The inner lead frame may be adjacent to the depression, and may be semicircular, located around the depression, as shown. By forming the inner lead frame in a semicircular shape, it is easy to form a plurality of lead frames in a large amount, and the process of connecting the bonding wires in the future is easy. On the other hand, the lead terminal may be bent into a shape suitable for extending to the outside and mounted on the substrate.

The package housing 31 supports the heat dissipation main body 31 and the lead frame 33 spaced apart from each other. The package housing 31 surrounds sidewalls of the heat dissipation body 31. In this case, the package housing 31 may have a through hole exposing at least a portion of the side wall of the heat dissipation body 31. As the sidewall of the heat dissipation body 31 is exposed through the through hole, heat dissipation characteristics through the heat dissipation body 31 may be improved. In addition, in order to support the heat dissipation main body 31, a circle facing inward may be formed on the lower surface of the heat dissipation main body 31. A locking step may be formed on the lower surface of the heat dissipation main body 31 to be supported by the frame.

A part of the package housing 31 is interposed between the lead frame 33 and the heat dissipation body 31. In addition, a part of the package housing 31 extends above the lead frame 33. In this case, the package housing 31 has an opening for exposing the recessed portion of the heat dissipation main body 35 and the internal lead frame 33. The opening of the package housing 31 extending above the lead frame 33 provides a receiving groove for accommodating the lens.

A lead terminal extending from the inner lead frame 33 penetrates through the package housing 31 and protrudes outward. To this end, the package housing 31 is provided with a through hole through which the lead terminal passes.

The package housing 31 may have a cylindrical shape, but is not limited thereto, and may have various shapes, such as a rectangular cylindrical shape, as shown.

The package housing 31 may be formed using a plastic molding resin such as a liquid crystal polymer or a poly phthalamide (PPA) resin using an insert molding technique. That is, the package housing 31 may be formed by aligning the heat dissipation body 35 and the pair of lead frames 33 at appropriate intervals and molding a plastic-based liquid resin. Thus, the required shape of the package housing 31 is easily achieved.

The LED die 37 is located at the bottom of the recess of the heat dissipation body 35. The LED die 37 may have a pair of electrodes on the top surface (in the case of flip chip), or electrodes on the top and bottom surfaces, respectively.

When the bottom surface has an electrode, the light emitting diode die 37 may be adhered to the heat dissipation main body 35 using a conductive adhesive such as silver epoxy or a transparent paste. Since the heat dissipation body 35 is a conductive material, the LED die 37 is electrically connected to the heat dissipation body 35 through silver epoxy.

A pair of bonding wires electrically connect the pair of lead frames 33 and the light emitting diode die 37. When one electrode of the light emitting diode die 37 is bonded to the heat dissipation body 35, one of the bonding wires connects the one lead frame 33 and the light emitting diode die 37, and the other Bonding wires connect the other lead frame 33 and the heat dissipation body 35. When the light emitting diode die 37 has a pair of electrodes on the top surface, that is, when the light emitting diode die 37 is a flip chip, the pair of bonding wires may be formed by the respective lead frames ( 33) and each electrode of the LED die 37.

On the other hand, an encapsulant 39 filling the depression of the heat dissipation main body 35 seals the light emitting diode die 37. The encapsulant 39 may be formed at a sufficient height to cover the bonding wire, and may fill up to an upper surface of the package housing 31. The encapsulant 39 may be formed using a resin such as silicone or epoxy. In addition, the encapsulant 39 may contain a phosphor and / or a diffusion agent.

A lens (not shown) may be positioned on the encapsulant 39. The lens may be inserted into and fixed to the opening of the package housing 31. The lens is preferably in close contact with the encapsulant 39. On the other hand, when the lens is used, since the lens can protect the light emitting diode die 37, the encapsulant 39 can be omitted.

4 is a perspective view of a heat dissipation body 55 for explaining a light emitting diode package according to another embodiment of the present invention, and FIG. 5 is a view for explaining a light emitting diode package manufactured using the heat dissipation body 55 of FIG. It is a cross section.

Referring to FIG. 4, the light emitting diode package according to the present embodiment adopts a heat dissipation body 55 having a depression, as described with reference to FIGS. 2 and 3. However, unlike the heat dissipation body 35 of FIGS. 2 and 3, the heat dissipation main body 55 further has lead frame receiving grooves 54 connected to the depression. The receiving grooves 54 are formed on the heat dissipation main body 55 and may be formed together while the recess is formed.

Referring to FIG. 5, a pair of lead frames 53 are inserted into and positioned in the lead frame receiving grooves 54, respectively. The lead frames 53 are insulated from the heat dissipation body 55. Each lead frame 53 includes an inner lead frame positioned adjacent to the depression of the heat dissipation main body 51 and a lead terminal extending outward from the inner lead frame. The inner lead frame may be adjacent to the depression, and may be semicircular, located along the periphery of the depression, as described with reference to FIGS. 2 and 3.

As described with reference to FIGS. 2 and 3, the package housing 51 is positioned to surround the heat dissipation main body 55. In addition, a portion of the package housing 51 spaces the lead frames 53 and the heat dissipation main body 55 and fills the receiving grooves 54. As described with reference to FIGS. 2 and 3, the package housing 51 may be formed using an insert molding technique.

Meanwhile, as described with reference to FIG. 3, the LED die 57 and the bonding wire are connected, and the encapsulant 59 fills the inside of the recess of the heat dissipation main body 55. Since the lead frame 53 is positioned relatively lower than that of FIG. 3, the bonding wires are easily connected, and the encapsulant 59 may also be formed relatively low. In addition, as described above, a lens may be positioned on the encapsulant 59.

According to the present embodiment, since the lead frames 53 are located in the receiving grooves 54 of the heat dissipation body 55, the height of the LED package may be lowered.

 According to embodiments of the present invention, by adopting a heat radiating body, it is possible to provide a light emitting diode package that can improve the heat dissipation characteristics while maintaining the size of the light emitting diode package. In addition, it is possible to provide a light emitting diode package capable of minimizing light loss by improving the reflectance of the reflective surface.

Claims (5)

A heat dissipation body having a depression on an upper surface thereof; A pair of lead frames; And And a package housing configured to support the heat dissipation body and the lead frame to be spaced apart from each other. The light emitting diode package of claim 1, further comprising a reflective coating film formed on the bottom and sidewalls of the depression. The light emitting diode package of claim 1 wherein the package housing is plastic formed using an insert molding technique. The light emitting diode package of claim 1, wherein the heat dissipation body has a pair of lead frame receiving grooves connected to the depression. The light emitting device of claim 1, further comprising: a light emitting diode die mounted at a bottom of the depression; And a pair of bonding wires electrically connecting the pair of lead frames and the LED die.

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