KR20080006160A - Led package - Google Patents

Abstract

An LED package is provided to decrease heat radiation from the LED package by uniformly distributing a current on an overall surface of a wide LED package. An LED package includes a lead frame(210), a light emitting unit(100), a first connector, and a second connector(240). The light emitting unit includes plural LED chips having first electrodes. The light emitting unit includes a second electrode, which is commonly connected to at least two LED chips. The first connector is connected to the first electrode. The second connector is connected to the second electrode. The first electrode is an n-type electrode. The first electrode is commonly connected to four LED chips.

Description

Light emitting device package {LED package}

1 is a cross-sectional view showing an example of a conventional light emitting device.

2 is a perspective view showing an example of a conventional light emitting device package.

3 is a plan view showing the arrangement of the light emitting device package of the present invention.

4 is a side cross-sectional view of FIG. 3.

5 is a plan view showing a first embodiment of a light emitting device package of the present invention.

6 is a side cross-sectional view showing a first embodiment of a light emitting device package of the present invention.

7 is a circuit diagram showing a first embodiment of a light emitting device package of the present invention.

8 is a side sectional view showing a second embodiment of a light emitting device package of the present invention.

9 is a plan view showing a second embodiment of a light emitting device package of the present invention.

10 is a plan view showing a third embodiment of a light emitting device package of the present invention.

11 is a side sectional view showing a fourth embodiment of a light emitting device package of the present invention.

12 is a schematic view showing an example of an arrangement of a light emitting unit of a light emitting device package according to the present invention.

13 is a schematic view showing another example of the arrangement of the light emitting portion of the light emitting device package of the present invention.

<Brief description of the main parts of the drawing>

100: light emitting unit 110, 150: light emitting device chip

120: n-type electrode 130: p-type electrode

140: insulating layer 200: package

210: lead frame 220: wire

230: first connection portion 240: second connection portion

250: thermal conductive layer

The present invention relates to a light emitting device package, and more particularly, to a light emitting device package having a large light emitting surface.

Light Emitting Diodes (LEDs) are well-known semiconductor light emitting devices that convert current into light.In 1962, red LEDs using GaAsP compound semiconductors were commercialized, along with GaP: N series green LEDs. It has been used as a light source for display images of electronic devices, including.

The wavelength of light emitted by such LEDs depends on the semiconductor material used to make the LEDs. This is because the wavelength of the emitted light depends on the band-gap of the semiconductor material, which represents the energy difference between the valence band electrons and the conduction band electrons.

Gallium nitride compound semiconductors (Gallium Nitride: GaN) have attracted much attention in the field of high-power electronics development due to their high thermal stability and wide bandgap (0.8-6.2 eV). One reason for this is that GaN can be combined with other elements (indium (In), aluminum (Al), etc.) to produce semiconductor layers that emit green, blue and white light.

In this way, the emission wavelength can be adjusted to match the material's characteristics to specific device characteristics. For example, GaN can be used to create white LEDs that can replace incandescent and blue LEDs that are beneficial for optical recording.

In addition, in the case of the conventional green LED, it was initially implemented as GaP, which was inefficient as an indirect transition type material, and thus practical pure green light emission could not be obtained. However, as InGaN thin film growth succeeded, high brightness green LED could be realized. It became.

Because of these and other benefits, the GaN series LED market is growing rapidly. Therefore, since commercial introduction in 1994, GaN-based optoelectronic device technology has rapidly developed.

Since the efficiency of GaN light emitting diodes outperformed the efficiency of incandescent lamps and is now comparable to that of fluorescent lamps, the GaN LED market is expected to continue to grow rapidly.

Recently, such LEDs provide a variety of applications such as mobile phones, vehicles, and traffic lights, and are currently bringing about a revolution in the lighting market, which is typically occupied by ordinary white lamps according to the development of high power and high brightness LEDs.

As an example of such a commercialization, research is being conducted to replace the lamp of a backlight unit (BLU) of a liquid crystal display (LCD) with a high output LED array to enable high quality display applications.

The LED package used for such lighting is not only the reliability of the LED but also the uniformity of light and the light emitting area.

1 illustrates an example of a general GaN-based LED device, and illustrates a horizontal LED having two electrodes on the same plane.

The horizontal LED 10 includes a buffer layer 12 made of GaN material, an n-type semiconductor layer 13, an active layer 14, and a p-type semiconductor layer on a substrate 11 such as sapphire, SiC, GaN, or the like. In the structure in which the n-type semiconductor layer 13 is exposed, the n-type electrode 16 and the p-type electrode 17 are formed, respectively.

In this LED 10 structure, the n-type electrode 16 and the p-type electrode 17 are formed in the form of a pad for wire bonding to a package, and passivation is performed on the outer surface of the LED 10. Dielectric layer 18 is formed.

FIG. 2 shows a package of the LED 10 chip. After attaching the LED 10 chip to the package lead frame 21 using the thermal conductive layer 22, the LED 10 chip is attached to the lead wire 23. The wires 24 are bonded to the electrodes 16 and 17, and the encapsulation material 25 is filled on the LED 10 chip.

In the above-described high power LED package, as the size of the LED 10 chip increases, current does not flow uniformly throughout the LED 10 chip, resulting in a problem that the light emitting area is reduced, thereby increasing operating voltage and power consumption. There is a disadvantage in that unnecessary heat generation.

These problems have a devastating effect on product reliability, which limits the application of lighting applications and backlight unit modules.

An object of the present invention is to provide a light emitting device package having a light emitting surface of a large area with improved reliability.

As a first aspect for achieving the above technical problem, the present invention, the lead frame; A light emitting unit comprising a plurality of light emitting device chips having a first electrode, the light emitting unit having a second electrode commonly connected to at least two or more chips of the plurality of light emitting device chips; A first connector connected to the first electrode; It is preferably configured to include a second connecting portion connected to the second electrode.

It is preferable that the first electrode is an n-type electrode and the second electrode is a p-type electrode.

The light emitting device chip may be configured in four, and the common first electrode may be connected to the four light emitting device chips in common.

The light emitting unit may be configured such that the arrangement of the plurality of light emitting device chips forms any one of 2 × 2, 2 × 3, 3 × 3, and 4 × 4, and each light emitting device chip has a shape of 3 The shape which has an angle more than a square can be achieved.

In addition, the light emitting unit may further include an encapsulation layer covering the light emitting part.

As a second aspect for achieving the above technical problem, the present invention, the lead frame; A light emitting unit comprising a plurality of light emitting device chips each having a first electrode located above and a second electrode located below and having a supporting plate commonly connected to the plurality of light emitting device chips; A first connection part connected to the support plate of the light emitting part; Preferably, the light emitting unit includes a second connection part connected to the ohmic electrode of the light emitting part.

Connection lines for connecting the plurality of first electrodes to each other may be further included.

In this case, the support plate is preferably connected in common to the second electrode of the light emitting device chip.

In addition, the second electrode may include a p-type electrode and a reflective electrode.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 3 shows four unit light emitting device chips 110 without separating the manufactured light emitting device chips 110, respectively, and is connected to each other in the form of two rows and two columns (2 × 2). Shows the floor plan composed of.

The n-type electrode 120 connected to each of the light emitting device chips 110 is formed at the center of the light emitting part 100.

In addition, the p-type electrode 130 is formed at one side of each light emitting device chip 110, and as shown in FIG.

The positions of the n-type electrode 120 and the p-type electrode 130 may be changed according to the layer structure of the light emitting device chip 110. Hereinafter, the arrangement of FIG. 3 will be described as an example.

4 illustrates the cross-sectional shape of FIG. 3, wherein each of the light emitting device chips 110 includes a buffer layer 112, an n-type semiconductor layer 113, an active layer 114, and a p-type semiconductor on the substrate 111. The layers 115 are sequentially positioned, and the p-type semiconductor layer 115 is connected to the p-type electrode 130.

In addition, the n-type semiconductor layer 113 is connected to the common n-type electrode 120, and an insulating layer (between each light emitting device chip 110 and an outer surface of the light emitting device chip 110) to enable only a current path through the package wire. 140 is provided.

In this case, the transparent conductive layer 116 may be positioned between the p-type semiconductor layer 115 and the p-type electrode 130.

5 and 6 illustrate the state in which the above-described light emitting unit 100 is bonded by the wire 220.

In this case, the common n-type electrode 120 is connected by a wire 220 to one first connector 230 installed in the lead frame 210 of the package 200, and each light emitting device chip 110. The p-type electrode 130 may be connected to the plurality of second connectors 240 installed in the lead frame 210 by the wire 220.

5 and 6, the second connectors 240 are positioned at both sides of the light emitter 100, and thus the p-type electrodes 130 of the two light emitting device chips 110 adjacent to the second connectors 240 are disposed. ) Is connected.

In this case, the light emitting part 100 may be coupled to the lead frame 210 by the thermal conductive layer 250.

In addition, an encapsulation layer 260 may be formed on the light emitting part 100.

As such, when the plurality of light emitting device chips 110 are configured in one single package to configure the light emitting device package, the illuminance of the package is greatly improved.

The light emitting device chip 110 includes two rows and three columns (2 × 3), three rows and three columns (3 × 3), four rows and four columns (4 × 4) in addition to the two rows and two columns (2 × 2) described above. Etc. arrangement is possible.

In addition, when the plurality of light emitting device chips 110 are arranged to form a package, current spreading is much higher than that of one light emitting device chip having the same size as the plurality of light emitting device chips 110. It is excellent and can effectively solve the heat dissipation problem which is the biggest problem in the high output light emitting device.

As such, when the current spreading is excellent, the uniformity of the entire light emitting device may be improved, the luminous efficiency may be improved, and the overall reliability may be improved.

That is, since each of the light emitting device chips 110 are connected in parallel as shown in FIG. 7, simultaneous driving is possible according to a voltage and a current source, and current can be evenly flowed to four chips, thereby providing a uniform light emitting area compared to a large chip. Can be obtained.

This has the advantage of spreading over four chips for thermal issues that can be concentrated in one area and affect reliability.

In addition, if the multi-chip package can be manufactured in a wafer state, it can be transformed into three rows, three columns (3 × 3), and four rows and four columns (4 × 4) according to the required chip size. It is more efficient than the area chip packaging process.

8 illustrates an embodiment in which the package 200 is configured by using a plurality of vertical light emitting device chips 150.

In the vertical light emitting device chip 150, the n-type electrode 160 is positioned on an upper side of the semiconductor layer including the n-type semiconductor layer 151, the active layer 152, and the p-type semiconductor layer 153. The p-type electrode 170 is positioned under the p-type semiconductor layer 153.

The structure of the vertical light emitting device chip 150 is positioned on the support layer 151 and the substrate is separated and removed.

The support layer 151 supports the light emitting device chip 150 while the substrate of the vertical light emitting device chip 150 is separated, and may be made of a metal or a conductive semiconductor.

In this case, the p-type electrode 170 may be formed of a transparent electrode 171 and an ohmic electrode 172.

The light emitting unit 100 including the vertical light emitting device chip 150 is bonded to the first connection unit 230 on which the support layer 151 is fixed to the lead frame 210, and the n-type electrode 160 is The wire 220 is bonded to the second connector 240.

In this case, the n-type electrodes 160 positioned on the plurality of light emitting device chips 150 may be connected to each other by the connection line 180.

In FIG. 9, as described above, the n-type electrode 160 of the plurality of light emitting device chips 150 is connected by the connection line 180.

The connection line 180 may improve current spreading by connecting the n-type electrodes 160 to each other, and effectively solve the heat dissipation problem, which is the biggest problem in the high output light emitting device.

As shown in FIG. 9, the connection line 180 may use a shape for connecting the n-type electrode 160 in an annular shape, and in some cases, the connection line 180 may be used in a cross shape or a fragment shape.

Meanwhile, as illustrated in FIG. 10, the n-type electrode 161 may be formed in common with the light emitting device chips 150. In this case, the connection line 180 is not necessary.

That is, by forming the electrodes 161 which are commonly connected to each other at the center of the plurality of light emitting device chips 150, the common electrode may be formed by a simpler process.

In FIG. 11, the n-type electrode 162 is formed of a transparent electrode material and is connected to an upper surface of the plurality of light emitting device chips 150.

As such, when the n-type electrode 162 is formed of a transparent electrode material such as indium tin oxide (ITO), the current spreading effect is improved, and thus a uniform light emitting surface can be obtained.

In the above-described case, the cross-section of the light emitting device chips 150 and 110 constituting the light emitting unit 100 has been described as an example. However, rectangular and other polygonal light emitting device chips may be used.

12 shows an example in which the light emitting unit 100 is configured by using a triangular light emitting device chip. In particular, the right-angled triangular light emitting device chips may be configured together to form a rectangular shape.

FIG. 13 shows an example in which the light emitting unit 100 is configured by using a hexagonal light emitting device chip.

As such, the light emitting unit 100 may be configured by using a plurality of light emitting device chips in various polygonal shapes, and the light emitting device chip includes both a horizontal structure including a flip chip structure and a light emitting device chip having a vertical structure. Can be used.

The above embodiment is an example for explaining the technical idea of the present invention in detail, and the present invention is not limited to the above embodiment, various modifications are possible, and various embodiments of the technical idea are all protected by the present invention. It belongs to the scope.

The present invention as described above has the following effects.

First, a large light emitting area package can be realized by arranging a plurality of light emitting device chips.

Second, in implementing a package having a large light emitting area, current spreading is improved to enable uniform light emission and to solve a thermal problem.

Third, the wire bonding may not be in direct contact with the device layer may cause physical damage to the device.

Fourth, as described above, the reliability of the package can be improved by solving the current spreading and thermal problems.

Claims (15)

A lead frame; A light emitting unit comprising a plurality of light emitting device chips having a first electrode, the light emitting unit having a second electrode commonly connected to at least two or more chips of the plurality of light emitting device chips; A first connector connected to the first electrode; The light emitting device package, characterized in that comprising a second connecting portion connected to the second electrode. The light emitting device package according to claim 1, wherein the first electrode is an n-type electrode. The light emitting device package of claim 1, wherein the common first electrode is commonly connected to four light emitting device chips. The light emitting device package according to claim 1, wherein the light emitting unit comprises an arrangement of the plurality of light emitting device chips in any one of 2x2, 2x3, 3x3, and 4x4. . The light emitting device package according to claim 1, wherein the light emitting part has a polygonal shape of a triangular shape or more. The light emitting device package of claim 1, further comprising an encapsulation layer covering the light emitting part. A lead frame; A light emitting unit comprising a plurality of light emitting device chips each having a first electrode located above and a second electrode located below and having a supporting plate commonly connected to the plurality of light emitting device chips; A first connection part connected to the support plate of the light emitting part; And a second connection part connected to the ohmic electrode of the light emitting part. The light emitting device package of claim 7, further comprising a connection line connecting the plurality of first electrodes to each other. 8. The light emitting device package according to claim 7, wherein the first electrode is an n-type electrode. The light emitting device package according to claim 7, wherein the support plate is commonly connected to a second electrode of the light emitting device chip. 8. The light emitting device package of claim 7, wherein the second electrode comprises a p-type electrode and a reflective electrode. The light emitting device package according to claim 7, wherein the light emitting part has a polygonal shape of a triangular shape or more in a plane in which light is emitted. The light emitting device package according to claim 7, further comprising an encapsulation layer covering the light emitting part. The light emitting device package according to claim 7, wherein the first electrode is connected to the plurality of light emitting device chips in common. The light emitting device package according to claim 14, wherein the first electrode is a transparent electrode.

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