KR101071839B1

KR101071839B1 - Light emitting device package

Info

Publication number: KR101071839B1
Application number: KR1020070086115A
Authority: KR
Inventors: 서부완; 허훈; 김용석
Original assignee: 엘지이노텍 주식회사; 엘지전자 주식회사
Priority date: 2007-08-27
Filing date: 2007-08-27
Publication date: 2011-10-11
Also published as: KR20090021532A

Abstract

The present invention relates to a light emitting device package, and more particularly, to a light emitting device package capable of improving color purity and color reproducibility. This invention, the package body; An electrode formed on the package body; At least two light emitting elements electrically connected to the electrodes and emitting light of different colors; It characterized in that it comprises a phosphor layer located above the light emitting device.

Package, light emitting element, phosphor, white, substrate.

Description

Light emitting device package

The present invention relates to a light emitting device package, and more particularly, to a light emitting device package capable of improving color purity and color reproducibility.

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 high thermal stability and a wide bandgap (0.8 to 6.2 eV), which has attracted much attention in the development of high-power electronic components including LEDs.

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.

Due to the advantages of these GaN-based materials, the GaN-based LED market is growing rapidly. Therefore, since commercial introduction in 1994, GaN-based optoelectronic device technology has rapidly developed.

Currently, there are two major technologies for implementing white devices using GaN-based LEDs. The first method is to realize a white color by combining phosphor material on a blue chip or a UV light emitting diode chip in the form of a single chip, and the second method is a method of obtaining two colors by combining two or three LED chips with each other. have.

An object of the present invention is to provide a semiconductor light emitting device package having stable optical characteristics and high color reproducibility by using a light emitting device having a multichip of blue and green light emission and a red phosphor.

As a first aspect for achieving the above technical problem, the present invention, the package body; An electrode formed on the package body; At least two light emitting elements electrically connected to the electrodes and emitting light of different colors; It characterized in that it comprises a phosphor layer located above the light emitting device.

As a second aspect for achieving the above technical problem, the present invention, the package body; An electrode formed on the package body; At least one light emitting element electrically connected to the electrode; It characterized in that it comprises a red phosphor layer located above the light emitting device.

In the present invention, in the light emitting device package using the multi-chip, it is possible to obtain a stable optical property by replacing a device having poor optical properties with a phosphor, and in particular, has the effect of having high color reproducibility and color rendering property.

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

While the invention allows for various modifications and variations, specific embodiments thereof are illustrated by way of example in the drawings and will be described in detail below. However, it is not intended to be exhaustive or to limit the invention to the precise forms disclosed, but rather the invention includes all modifications, equivalents, and alternatives consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being present on another element "on," it may be directly on the other element or there may be an intermediate element in between . If a part of a component, such as a surface, is expressed as 'inner', it will be understood that this means that it is farther from the outside of the device than other parts of the element.

Furthermore, relative terms such as "beneath" or "overlies" refer to the relationship of one layer or region to one layer or region and another layer or region with respect to the substrate or reference layer, as shown in the figures. Can be used to describe.

It will be understood that these terms are intended to include other directions of the device in addition to the direction depicted in the figures. Finally, the term 'directly' means that there is no element in between. As used herein, the term 'and / or' includes any and all combinations of one or more of the recorded related items.

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers, and / or regions, such elements, components, regions, layers, and / or regions It will be understood that they should not be limited by these terms.

These terms are only used to distinguish one element, component, region, layer or region from another region, layer or region. Thus, the first region, layer or region discussed below may be referred to as the second region, layer or region.

As one example of a light emitting device using color conversion, such as a white light emitting device, white light may be implemented using a blue light emitting device and a yellow phosphor.

For example, using a blue light emitting element as a reference light source, when blue light emitted from the blue light emitting element is projected onto a YAG (Yttrium Aluminum Garnet) phosphor, which is a yellow phosphor, the yellow phosphor is excited by the incident light and emits light. Silver emits light in a wavelength band of 500 nm to 780 nm, and white may emit light due to a mixture of these lights.

However, in this example, because of the wide wavelength interval of blue and yellow, the glare effect due to color separation can be caused. In addition, it is not easy to adjust the same color coordinates, color temperature, color rendering index, color conversion may occur depending on the ambient temperature.

In particular, when the backlight unit is manufactured using the light emitting device, the color reproduction ratio of NTSC is limited to about 65%.

On the contrary, the color reproducibility may be more than 100% of that of NTSC by using a red, green, and blue light emitting device to implement white as a multi-chip.

However, when white is implemented as a multi-chip in this way, the operating voltage is uneven for each chip, the output of the chip is changed according to the ambient temperature, color coordinates may vary, and a driving circuit should be added.

In particular, as shown in FIG. 1 and FIG. 2, as can be seen from the wavelength dependence and power dependence of the red light emitting device chip according to the temperature-specific current, the current and the temperature of the red, green, and blue light emitting device chips are different. The color coordinate change caused by the red chip may be a problem, and thus, the entire color coordinate of the backlight unit may be changed.

As a method to solve such a limitation, two light emitting devices emitting two colors and a phosphor excited by the light emitting device can be used.

For such phosphors, using red phosphors may be more effective in solving the above limitations. Therefore, in order to form a white light emitting device package, a red phosphor provided with a green light emitting device and a blue light emitting device and excited by light emitted from the green light emitting device and the blue light emitting device can be used.

As shown in FIG. 3, light emitting devices 30 and 40 emitting different colors are provided on the package body 20 on which the electrodes 21 and 22 are formed, and on the light emitting devices 30 and 40, light emitting devices are provided. The phosphor layer 50 capable of changing the wavelength of light emitted from 30 and 40 is positioned. The phosphor layer 50 may be formed by mixing the phosphor powder 60 in the molding part.

The substrate 10 constituting the package body 20 may be formed of insulated silicon or ceramic, may be an insulated heat sink, or may be a lead terminal.

The electrode formed on the substrate 10 may include a first electrode 21 connected to one of the electrodes of the light emitting devices 30 and 40, and a second electrode connected to the remaining electrodes of the light emitting devices 30 and 40. 22).

In this case, the second electrode 22 may be formed to extend below the substrate 10 so that the light emitting device package may be easily mounted on a printed circuit board (not shown).

The first electrode 21 and the second electrode 22 may be formed through a printing technique. In addition, the first electrode 21 and the second electrode 22 may be formed of a metal material including copper or aluminum having excellent conductivity, and may be electrically disconnected from each other.

The light emitting devices 30 and 40 may be mounted on the package body 20 in the form of top emission or flip chip. In FIG. 3, the vertical light emitting devices 30 and 40 are coupled to each other. An example is shown.

The light emitting devices 30 and 40 that emit blue and green light, respectively, are GaN-based light emitting devices. An n-type GaN layer, an active layer, and p- that are sequentially stacked on a sapphire (Al ₂ O ₃ ) substrate are sequentially stacked. A GaN layer and a p-type electrode. In correspondence with the p-type electrode, an n-type electrode is provided on the n-type GaN layer.

In this case, the active layer includes a quantum well layer and a quantum barrier layer, respectively. Examples of the active layer include GaN / InGaN / GaN, AlGaN / InGaN / AlGaN, and the like. The active layer may have a structure of any one of a multi-quantum well or a single quantum well.

In order to achieve a vertical structure, a conductive support layer may be formed on the p-type electrode, the support layer may be used to remove the sapphire substrate, and the n-type electrode may be formed on the removed n-type GaN layer.

In the light emitting devices 30 and 40 having such a structure, as shown in FIG. 3, the support layer of the light emitting devices 30 and 40 is connected to the first electrode 21, and the n-type electrode is formed through the wire 23. It may be connected to the second electrode 22.

As described above, the phosphor layer 50 formed on the light emitting devices 30 and 40 may be formed by mixing the red phosphor 60 with a resin such as a silicone gel or an epoxy resin.

The molding part may be formed through an injection process using a mixture of the transparent epoxy resin and the red phosphor 60. In addition, it may be formed by using a separate mold, and then formed by pressing or heat-treating it, and may be formed in various shapes such as an optical lens shape, a flat plate shape, and a shape having predetermined irregularities on the surface.

Meanwhile, as shown in FIG. 4, the mounting groove 11 is formed in the center region of the substrate 10 on which the light emitting devices 30 and 40 chips of the package body 20 are mounted. A predetermined slope can be formed on the side wall surface of the.

Therefore, the light emitting device chips 30 and 40 are mounted on the lower surface of the mounting groove 11, and the reflection of the light emitted from the light emitting device chips 30 and 40 is maximized due to the sidewall surface having a predetermined inclination and the light emitting efficiency is improved. You can increase it. In addition, the package body 20 may further include a heat sink 70 for dissipating heat generated from the chips of the light emitting devices 30 and 40 to the outside.

In this case, the substrate 10 may be formed using a semiconductor wafer such as silicon, and when the substrates 10 are separated from each other by wet etching, the side surfaces may be inclined.

In addition, the phosphor layer 50 may be filled in the mounting groove 11, and may be formed such that the outer surface thereof is flat or has a lens shape.

In the light emitting device package, primary light is emitted from the blue light emitting device 30 and the green light emitting device 40, and the red phosphor 60 is excited by the primary light to emit secondary wavelength light that is converted into wavelengths. With these mixed colors, the color of the desired spectral region can be realized.

As an embodiment of the backlight unit fabricated using the above-described light emitting device package, the green light emitting device 40 for emitting green light having a band of peak wavelength of 510 nm to 550 nm and the band of peak wavelength of 420 nm to 460 nm The light source which consists of the blue light emitting element 30 which emits blue light which is phosphorus, and the red fluorescent substance which is excited by this light source and emits red light with peak wavelength of 610 nm-680 nm were provided, and the mixing means which mixes so that it may make white light may be provided.

In addition, by adjusting the emission intensity of the green light and blue light emitted from the green light emitting device 40 and the blue light emitting device 30, the full width at half maximum hw of the spectrum of green light is 30 nm to 40 nm, and the full width at half maximum hw of the spectrum of blue light is produced. From this, it is possible to produce a spectrum of red light having a half width hw of 20 nm to 30 nm.

The light emitting devices 30 and 40 described above may emit light other than blue and green, and the phosphor layer 50 may also use the phosphor 60 emitting light other than red.

In this way, the light emitting elements 30 and 40 emitting different colors and the phosphor 60 excited and excited by the light emitted from at least one of the light emitting elements 30 and 40 have various colors. Can implement light.

As described above, the present invention can manufacture a light emitting device package having a high color reproducibility due to the characteristics of higher luminous efficiency, high color rendering, stable color temperature, and color coordinates than when a yellow phosphor is used for a blue light emitting device.

When the light emitting device package is used for the backlight unit of the liquid crystal display device, since the red phosphor is used for the blue and green light emitting devices, color coordinates and color temperature caused by the red light emitting devices are not changed, and thus, the optical unit may have stable optical characteristics.

In addition, since the red light emitting chip is not used, the bin management point of the multi-light emitting device chip is reduced, and thus the yield is increased. It can act more advantageously than

In addition, the color reproducibility is higher than that of using a yellow phosphor in a blue light emitting device, and color reproducibility (100% or more), which is equivalent to that of using an RGB multi-chip, can be assured, thereby enabling a deeper and clearer color.

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.

1 is a graph showing wavelength dependence according to current for each temperature of a red light emitting device.

2 is a graph showing power dependency according to current for each temperature of a red light emitting device.

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

4 is a cross-sectional view showing a second embodiment of the light emitting device package of the present invention.

Claims

Package body;

A first electrode and a second electrode formed on the package body;

A blue light emitting device electrically connected to the first electrode;

A green light emitting device electrically connected to the second electrode;

A red phosphor layer positioned above the blue light emitting device and the green light emitting device;

And a heat sink included in the package body and thermally connected to the blue light emitting device and the green light emitting device.

The light emitting device package of claim 1, wherein the package body comprises any one of insulated silicon, ceramic, and insulated heat sink.

The light emitting device package according to claim 1, wherein the red phosphor layer includes a red phosphor in a molding part positioned on the blue light emitting device and the green light emitting device.

The light emitting device package of claim 1, wherein the first electrode and the second electrode are electrically isolated from each other.

The light emitting device package of claim 1, wherein the blue light emitting device and the green light emitting device are mounted in a mounting groove formed in the package body.

delete

The light emitting device package according to claim 1, wherein the blue light emitting device and the green light emitting device are any one of a side type, a flip chip type, and a vertical type light emitting element.

The light emitting device package according to claim 1, wherein the blue light emitting device and the green light emitting device are GaN-based light emitting devices.

The method of claim 1, wherein the blue light emitting device and the green light emitting device,

A conductive support layer;

A p-type electrode on the conductive support layer;

An active layer on the p-type electrode;

And an n-type electrode positioned on the active layer.

The light emitting device package of claim 1, wherein the red phosphor layer comprises a red phosphor in a silicone gel or an epoxy resin.