KR20090083202A - Led package and back light unit using the same - Google Patents

Abstract

An LED package and a backlight unit using the same are provided to prevent the generation of shadow, obtain wide directivity angle and to minimize interfacial delamination. A pattern electrode is formed in the upper side of a substrate(20). A solder pad is formed on the bottom surface of substrate. The solder pad is connected to the pattern electrode through the through hole. An LED chip(40) is mounted in the upper side of the substrate. A fluorescent substance block(30) is mounted in the upper side of the substrate. The fluorescent substance block covers the upward and lateral part of the LED chip. The fluorescent substance block decides on the light emitted from the LED chip to the upward and lateral part with the emission.

Description

LED package and backlight unit using the same {LED package and back light unit using the same}

The present invention relates to an LED package and a backlight unit using the same, and more particularly, to an LED package capable of emitting light upward and to the side and a backlight unit using the same.

A light emitting diode (hereinafter, referred to as an LED) is a semiconductor device capable of realizing various colors by configuring a light emitting source by changing compound semiconductor materials such as GaAs, AlGaAs, GaN, InGaN, and AlGaInP. Say. At present, many such semiconductor devices have been adopted in the form of packages in electronic components.

The current application trend of the LED package configured as described above is progressing from the simple indicator of the electronic device to the backlight unit of the indirect lighting / LCD TV through the flash lamp of the mobile phone, and furthermore, the possibility of the direct lighting. This is high.

Typically, a backlight unit employed in a flat panel display or the like has edge type (called edge type or side view type) and direct type (direct type or top view) depending on the position of a light source (lamp) (eg, LED package). Method).

In general, an edge type backlight unit has a structure in which a lamp unit (eg, an LED package) is installed at a side surface of the light guide plate, and a direct backlight unit has one or more lamp units (eg, an LED package) in a line on a lower surface of the diffuser plate. It is arranged to irradiate light on the entire flat panel display.

In case of installing the direct type backlight unit directly on the flat panel display device, one LED package must be installed for each pixel, and thus, a large number of LED packages must be used.

Accordingly, as shown in FIGS. 1 and 2, a plurality of backlight units including a pair of side view LED packages 12a and 12b are disposed on a top surface of a bar type base substrate 10 in a row. Is used. Such edge type LED packages (ie, LED packages with reflectors) have been proposed.

In the case of the backlight unit of Figs. 1 and 2, the left LED package 12a is installed to perform light emission only in the left direction, and the right LED package 12b is installed to perform light emission only in the right direction. That is, light is not emitted to the upper surface of the base substrate 10, but only light is emitted in the left direction and the right direction of the base substrate 10. In other words, the backlight unit of FIGS. 1 and 2 uses an edge type LED package.

The backlight unit as shown in FIGS. 1 and 2 uses fewer LED packages than the direct-type backlight unit because light spreads only from side to side to illuminate the entire screen.

However, the backlight unit of FIGS. 1 and 2 does not emit light to the upper surfaces of the LED packages 12a and 12b, and when viewed from the front, the backlight unit is also referred to as a shadow part along the long axis of the base substrate 10. Seems to have occurred. This not only degrades the picture quality, but it is also not good visually and reduces the reliability of the product.

In addition, in the backlight unit of FIGS. 1 and 2, a direction angle of about 60 degrees to about 80 degrees is obtained when most of the backlight units are not used. Thus, hemispherical lenses were additionally installed to widen the orientation angle to approximately 120 degrees. In this case, it is necessary to fabricate a lens that is sophisticated enough to obtain a desired orientation angle, and it is very difficult to manufacture the lens precisely. And even if the lens is manufactured, it is difficult to accurately attach the lens to the front surface (ie, the upper surface) of the LED package. Even if the lens is attached to the front of the LED package, it will not be able to achieve the desired orientation angle if it is not attached in the correct position.

The present invention has been proposed to solve the above-mentioned conventional problems, and an object thereof is to provide an LED package in which a shadow is generated and a wide direct angle can be obtained.

Another object of the present invention is to provide a backlight unit employing such an LED package.

In order to achieve the above object, the LED package according to a preferred embodiment of the present invention, the substrate on which the pattern electrode is formed; A light emitting device mounted on an upper surface of the substrate; And a phosphor block mounted on the upper surface of the substrate and covering the upper and side sides of the light emitting element to emit the light emitted from the light emitting element upward and side.

The size of the pattern electrode is smaller than the size of the upper surface of the substrate.

Solder pads are formed on the bottom of the substrate, and the solder pads are connected to the pattern electrodes through the through holes.

An auxiliary solder pad connected to the solder pad is formed at the side of the substrate.

On the other hand, in the backlight unit according to the embodiment of the present invention, one or more LED packages having the above-described configuration features are arranged.

According to the present invention of such a configuration has the following effects.

1) Since the LED package of the embodiment of the present invention emits light of the light emitting device upward and laterally through the phosphor block, the orientation angle is wider than that of the conventional side view LED package and the direct LED package. In addition, since the LED package of the embodiment of the present invention does not use a reflecting plate, the structure is simpler than that of the conventional edge type LED package and the direct type LED package.

2) In the LED package according to the embodiment of the present invention, the size of the pattern electrode is smaller than the size of the upper surface of the substrate, so that the interface separation generated by performing a process for bonding the phosphor block and the substrate (eg, oven curing, etc.). Minimize the effect.

3) In the LED package according to the embodiment of the present invention, the solder package is formed on the bottom surface of the substrate to allow surface mounting of the LED package.

4) In the LED package of the embodiment of the present invention, if the solder pad is difficult to solder, the secondary solder pad may be soldered, thereby providing ease of soldering and helping surface mounting of the LED package.

5) The backlight unit according to the embodiment of the present invention arranges LED packages capable of emitting light to the side and upward one by one, so that shadows (dark areas) do not occur on the base substrate even though fewer LED packages are used than in the prior art. do. This improves image quality and product reliability.

6) In the backlight unit of the embodiment of the present invention, since the LED package emits light in all directions, it is possible to obtain the effect of a surface light source such as a conventional CCFL (cold cathode fluorescent lamp).

Hereinafter, an LED package and a backlight unit using the same according to an embodiment of the present invention will be described with reference to the accompanying drawings. Hereinafter, it is assumed that the LED package is any SMD type package such as a ceramic package, a plastic package, a lead frame type package, and a plastic + lead frame type package.

3 to 5 are views for explaining the configuration of the LED package according to an embodiment of the present invention, Figure 6 is a coupling state diagram of FIG.

The LED package of the embodiment of the present invention includes the substrate 20, the phosphor block 30, and the LED chip 40.

The board | substrate 20 can be any if it can mount the LED chip 40 (light emitting element) at high density. For example, the material of the substrate 20 may include alumina, quartz, calcium zirconate, forsterite, SiC, graphite, fusedsilica, and mullite. Cordierite, zirconia, beryllia, and aluminum nitride, low temperature co-fired ceramic (LTCC), plastics, varistors, and the like. Preferably, it is best to manufacture using a ZnO series varistor material. This is because varistors of ZnO series have high thermal conductivity. The production of ZnO-based varistor material not only functions as a varistor, but also allows the LED package to be rapidly cooled due to the high thermal conductivity of the varistor itself. In the embodiment of the present invention, the material of the substrate 20 is assumed to be ceramic. The ceramic can be used as a multi-layer ceramic package (MLP) through the firing process by forming a metal conductor wiring pattern thereon.

Pattern electrodes 22 and 24 are formed on the upper surface of the substrate 20. The pattern electrode consists of a cathode electrode 22 and an anode electrode 24 spaced apart from each other. For example, the pattern electrodes 22 and 24 take the form of a lead frame plated with on (Ag). The anode electrode 24 is formed on the substrate 20 so as to be spaced apart from the cathode electrode 22 formed in the LED chip mounting region (ie, the center of the upper surface of the substrate) for electrical insulation.

Although the planar shape of the board | substrate 20 was made rectangular in the figure, it may be square. If the planar shape of the substrate 20 is square, the planar shape of the phosphor block 30 will also be square. As a result of the experiment, it was found that the direction of the orientation is generally larger than the case of the rectangular shape of the plane shape.

The size (length and width) of the pattern electrodes 22 and 24 is made smaller than the size (length and width) of the upper surface of the substrate 20. This is to minimize interfacial separation caused by performing a process (eg, oven curing) for bonding the phosphor block 30 and the substrate 20 later. That is, when the edges of the pattern electrodes 22 and 24 are exposed from the upper surface of the substrate 20 to the adjacent side surfaces, interfacial separation may occur by a process for bonding the phosphor block 30 and the substrate 20. . Thus, the interface separation can be minimized by removing the edge portions of each of the cathode electrode 22 and the anode electrode 24.

Solder pads 26 and 28 are formed on the bottom of the substrate 20. Solder pad 26 and solder pad 28 are each spaced apart. The solder pad 26 is connected to the cathode electrode 22 on the upper surface of the substrate through a through hole 25 penetrating through the substrate 20. The solder pad 28 is connected to the anode electrode 24 on the upper surface of the substrate through the through hole 25 penetrating through the substrate 20. The solder pads 26 and 28 allow surface mounting of the completed LED package.

Meanwhile, auxiliary solder pads 23 connected to the solder pads 26 and 28 are formed on the side of the substrate 20. The auxiliary solder pads 23 are additional matters and may be omitted as necessary. The auxiliary solder pad 23 is coated with Ag, AgPd, Au, or the like. In the case of AgPd, the ratio of Pd is selected in consideration of physical properties with the material of the substrate 20. The reason for using Ag, AgPd, Au is because it reacts well with solder. What is necessary is just to determine the coating material of the auxiliary solder pad 23 in consideration of each condition. As a method of coating Ag, AgPd, Au, etc., a conductive powder such as Ag, AgPd, Au, etc. is made into a fine powder, mixed with an organic binder, and pasted to form a paste. The method of coating on the wall is generally used. If there is a coatable method other than the above-mentioned coating method, it is employable. When the auxiliary solder pads 23 are completely filled in the respective grooves, the auxiliary solder pads 23 are thinly coated since the auxiliary solder pads 23 are more likely to fall off during sawing for a single product than the thin coatings. Of course, a printing (or plating) process may be further performed to prevent peeling that may occur in the reflow process after surface mounting of the LED package.

Therefore, when the LED package is mounted in a top view (ie, mounted as shown in FIG. 6), the solder pads 26 and 28 on the bottom surface of the substrate 20 are lower than the PCB substrate (not shown). Is bonded with lead, etc. Of course, in this case, when soldering the solder pads 26 and 28 is difficult, the auxiliary solder pad 23 may be soldered. That is, the auxiliary solder pad 23 provides for ease of soldering.

The LED chip 40 is mounted on the pattern electrode (for example, the cathode electrode 22). The LED chip 40 is electrically connected to the anode electrode 24 through the wire 42. Although not shown in the drawing, the LED chip 40 and the cathode electrode 22 on which the LED chip 40 is mounted are insulated by an insulating material. Of course, if necessary, the anode electrode may be used as the cathode electrode and the cathode electrode may be replaced with the anode electrode. In this case, the driving power application method may be reversed.

The phosphor block 30 is stacked on the upper surface of the substrate 20 on which the LED chip 40 is mounted. The phosphor block 30 is a mixture of phosphors (for example, yellow phosphor) and silicon (or epoxy) according to a predetermined compounding ratio. Naturally, the compounding degree of the phosphor is controlled so that the light from the LED chip 40 passes through the phosphor block 30 to represent white light.

The LED package according to the embodiment of the present invention does not have a separate reflector. Accordingly, the LED package according to the embodiment of the present invention is capable of emitting light to the left and right side (a direction; side) and to the top surface (b direction; upward) as shown in FIG. In addition, in FIG. 7, the long axis of the LED package 50 is set as the X axis and the short axis is set as the Y axis, and the luminance of the X axis and the Y axis is compared with Table 1 below.

<Table 1>

I _F [mA]        IV [cd]   Y axis (side emission)         20       0.256   X axis (upper emission)         20       0.578

That is, if the luminous intensity ("0.578") by the upper emission is 100%, the luminous intensity ("0.256") by the side emission is about 44% of the luminous intensity by the upper emission. In other words, the luminous intensity of side light emission relative to top light emission is approximately 50%.

On the other hand, looking at the orientation angle based on the X-axis and the orientation angle based on the Y-axis, as shown in the light distribution curve of FIG. The X-axis (short axis) orientation angle is about 160 degrees to 170 degrees as in FIG. 8A, and the Y-axis (long axis) orientation angle is about 140 degrees to 145 degrees as in FIG. to be.

Since the LED package according to the embodiment of the present invention does not have a reflecting plate, light from the LED chip 40 is emitted while being widely spread through the phosphor block 30. Thus, the LED package according to the embodiment of the present invention has a large orientation angle compared to the orientation angle of the conventional edge-type or direct-type LED package.

The manufacturing process for the LED package according to the embodiment of the present invention described above has not been described separately. In the LED package according to the embodiment of the present invention, the LED chip is mounted after, for example, the lead frame plate is placed on the substrate of the original plate. Thereafter, after the LED chip is wire bonded, the phosphor block plate of the original plate is placed in a molding method or the like, and then sawed by a sawing machine to complete the single package LED package as shown in FIG. Although no separate drawings have been presented for such a manufacturing process, those skilled in the same industry can fully manufacture using known techniques based on the structure described above.

9 is a diagram illustrating a backlight unit employing an LED package according to an exemplary embodiment of the present invention.

The LED package having the above-described configuration (that is, the LED package capable of emitting light in the side and upward) can be employed in the backlight unit. That is, the plurality of LED packages 50 are spaced apart from each other at predetermined intervals on the bar type base substrate 10 and are arranged in one line.

Of course, if necessary, the pair of LED packages 50 may be arranged in a group as shown in FIG. 2 as a group.

When the LED package 50 (that is, the LED package capable of emitting light to the side and upward) is installed on the base substrate 10 as shown in FIG. 9, a smaller number of LED packages can be used than in the related art (FIG. 2). do. In addition, light emission is performed in the lateral direction and upward, so that shading (also called a dark portion) does not occur along the long axis of the base substrate 10. This not only improves image quality as compared to the conventional art, but also improves the visual quality and reliability of the product.

On the other hand, the present invention is not limited only to the above-described embodiment, but can be modified and modified within the scope not departing from the gist of the present invention, the technical idea to which such modifications and variations are also applied to the claims Must see

1 and 2 are views for explaining the configuration of a general backlight unit.

3 to 5 are views for explaining the configuration of the LED package according to an embodiment of the present invention.

6 is a state diagram of FIG.

7 is a view for explaining a light emitting direction of the LED package according to an embodiment of the present invention.

8 is a view for explaining the orientation angle of the LED package according to an embodiment of the present invention.

9 is a diagram illustrating a backlight unit employing an LED package according to an exemplary embodiment of the present invention.

<Description of Symbols for Major Parts of Drawings>

20: substrate 22, 24: pattern electrode

23: secondary solder pad 25: through hole

26, 28: solder pad 30: phosphor block

40: LED chip 42: wire

50: LED package

Claims (5)

A substrate on which a pattern electrode is formed; A light emitting device mounted on an upper surface of the substrate; And LED package, characterized in that mounted on the upper surface of the substrate, covering the upper and side of the light emitting device, the phosphor block for emitting light emitted from the light emitting device upward and side. The method according to claim 1, The size of the pattern electrode LED package, characterized in that smaller than the size of the upper surface of the substrate. The method according to claim 1, An solder package is formed on the bottom surface of the substrate, the solder pad is connected to the pattern electrode through the through-hole LED package. The method according to claim 3, LED package, characterized in that the side of the substrate is formed with a secondary solder pad connected to the solder pad. A plurality of LED packages according to any one of claims 1 to 4 are arranged.

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