KR100609734B1 - Led package for use in back light of lcd and method of the same - Google Patents

Abstract

An LED package for an LED backlight light source having improved light efficiency is disclosed. The LED package for an LED backlight light source is formed on a printed circuit board, an upper surface of the printed circuit board and formed of an anode and a cathode electrode, a pad on which an LED chip is mounted and wire bonded, and formed on a bottom surface of the printed circuit board. And an external electrode terminal electrically connected to the pad, a lens portion molded to seal the LED chip mounted on the pad, and having a convex lens shape to condense and emit light to the outside.

LCD, Substrate, Convex, Lens, LED, Light Source, Reflection

Description

LED package for LCD backlight and its manufacturing method {LED PACKAGE FOR USE IN BACK LIGHT OF LCD AND METHOD OF THE SAME}

1 is a perspective view showing a side-emitting type LED package for a conventional LCD backlight.

FIG. 2 is a cross-sectional view showing a long axis of the side-emitting type LED package of FIG.

FIG. 3 is a diagram showing a uniaxial cross section of the side-emitting LED package of FIG.

Fig. 4 (a) is a schematic diagram showing the light distribution of light irradiated from the conventional LED light source, and Fig. 4 (b) is a schematic diagram showing the ideal light distribution.

5 is a perspective view showing a side-emitting LED package according to a preferred embodiment of the present invention.

FIG. 6 is a cross-sectional view taken along the line “A-A” of FIG. 5.

7 is a side cross-sectional view of FIG.

FIG. 8 is a perspective view illustrating a top surface of a printed circuit board for manufacturing the side-emitting type LED package shown in FIG. 5.

FIG. 9 is a bottom perspective view of the printed circuit board shown in FIG. 8. FIG.

FIG. 10 is a perspective view illustrating an LED chip mounted on the printed circuit board of FIG. 8.

FIG. 11 is a perspective view illustrating a state in which a lens unit is molded on an upper portion of the printed circuit board shown in FIG. 8.

FIG. 12 is a perspective view showing a reflective wall formed between a plurality of lens portions shown in FIG.

FIG. 13 is a perspective view showing one reflective wall of the reflective walls shown in FIG.

FIG. 14 is a schematic diagram schematically showing a movement path of light in the side-emitting package shown in FIG.

Fig. 15 (a) is a schematic view of the side of the Y-axis directional pattern in the state where there is no reflective wall on the side of the lens portion, and Fig. 15 (b) is a schematic view of the Y-axis directional pattern corrected by the reflection wall. .

16 is a flowchart illustrating a process of manufacturing an LED package according to a preferred embodiment of the present invention.

The present invention relates to an LED package for an LED backlight and a manufacturing method thereof, and more particularly, to an LED package for an LED backlight and its manufacture, which can improve light efficiency and brightness by improving the shape and manufacturing process of the lens unit and the reflective wall. It is about a method.

In general, a liquid crystal display device displays an image by changing the molecular arrangement of liquid crystals when power is supplied from each pixel. The liquid crystal display device itself is non-luminous and thus cannot be used in the absence of light. Thus, a backlight unit for uniformly irradiating the information display surface is provided.

The backlight unit includes a light source such as a fluorescent lamp or an LED, a light guide plate for spreading the light evenly on the entire LCD screen, and a prism sheet.

In the case of the light source, the light source is disposed on one side or two opposite sides of the outer frame of the screen, and the light emitted from the light source is injected to the side of the light guide plate overlapping the rear of the LCD panel.

Here, the LED as the backlight light source is disadvantageous for the uniform distribution of the light in the light guide plate as the point light source and the high brightness as compared with the fluorescent light of the long line light source.

Therefore, in order for the LED to have a better effect as an LED backlight source through the light guide plate, the directing pattern of the light emitted from the LED should be thin and spread along the side of the light guide plate like a fan. can do.

1 to 3, a conventional LED is shown, and this LED has a silver plated lead frame (1) protruding from both sides thereof, and the lead frame (1) is formed of a narrow and long groove by injection molding. The cup 2 is formed.

After attaching the LED chip 3 to the inside of the reflective cup 2 and bonding the wire 4, the lens unit 5 is formed by filling and curing a liquid transparent resin.

The lens unit 5 mainly uses an epoxy or silicon material, and in some cases, a phosphor powder may be added. That is, in order to realize white light, the blue LED chip is sealed with a resin in which yellow phosphors are mixed.

In addition, the amount and distribution of the phosphor in the resin determines the color coordinates of the white light, and the injection-molded reflecting cup basically forms a thin and wide spread light emitted from the LED.

However, after the resin is applied, a change occurs in the light directing pattern. In other words, the liquid resin is somewhat different depending on the material, but basically shrinks through the thermosetting process. The surface of the cured resin is naturally concave in the narrow wall gap of the reflecting cup, and the surface of the cured resin is naturally concave.

Therefore, the directing pattern of the light emitted from these LEDs has a shape as shown in Fig. 4A.

That is, when the side direction of the light guide plate is set to the X axis 7 and the thickness direction to the Y axis 8, the light directing pattern 9 is widely dispersed in the Y axis direction 8.

On the other hand, Fig. 4 (b) shows an ideal light directing pattern. That is, it has a pattern spreading widely in the X axis 7 direction and narrowly spreading in the Y axis 8 direction.

As described above, in the conventional LED package, the shape 6 of the lens unit 5 has a concave lens shape, thereby thickly dispersing the directional patterns of the thinly collected light, thereby greatly reducing the light injection efficiency in the light guide plate. There is a problem that the overall brightness of the LCD screen falls.

In addition, a hot spot may occur at an entrance to which light is irradiated into the light guide plate, and the uniformity of luminance of the entire LCD screen may be greatly reduced.

In case of manufacturing such a conventional LED package, in terms of quality and productivity, the molding of the individual reflection cups through the injection mold of a complicated structure and the application of a liquid resin in a uniform amount in the reflection cups are carried out. High difficulty process is required.

In particular, when the white light is implemented by including the phosphor powder in the resin, the optical properties are variable according to the application precision of the resin. That is, no matter how precise the mechanical device is, the variation in the discharge amount of the resin, the uneven formation of the upper surface after curing of the resin, and the amount and distribution of the phosphors in the chain are largely related to the uniformity of the light directing pattern and the color coordinate. affect.

Therefore, an object of the present invention has been proposed to solve the above problems, an object of the present invention is to control the light-directed pattern of the LED package to be suitable for the light guide plate LCD to increase the brightness and uniformity of the brightness of the LCD screen An LED package for a backlight light source is provided.

In addition, another object of the present invention is to provide a method of manufacturing an LED package for an LED backlight light source that can be greatly improved in reproducibility and productivity in an easy and simple process for the LED package.

In order to realize the above object of the present invention, the present invention is a printed circuit board; A pad formed on an upper surface of the printed circuit board and formed of a positive electrode and a negative electrode terminal, the pad of which an LED chip is mounted and wire bonded; An external electrode terminal formed on a bottom surface of the printed circuit board and electrically connected to the pad; An LED package for molding an LED chip mounted on the pad is sealed and includes a lens unit that condenses and emits light to the outside by having a convex lens shape.

In addition, in order to achieve another object of the present invention, the present invention provides a printed circuit board comprising a plurality of circuit units arranged in a row with each other, the electrical circuit for each circuit unit; Mounting an LED chip on a pad of the printed circuit board and performing wire bonding; A lens unit molding step of forming a plurality of LED chips disposed on the same line and an electrical connection along the plurality of arrangements of the circuit units; After the step, arranging a reflective wall in a space formed between the plurality of lens units by an attaching method; And it provides a method of manufacturing an LED package for an LED backlight light source comprising the step of cutting the printed circuit board to separate for each package.

Hereinafter, with reference to the accompanying drawings will be described in detail the structure of the LED package for an LCD bag according to an embodiment of the present invention.

5 to 7, the LED package proposed by the present invention is formed on a printed circuit board (hereinafter, the substrate; 10) and the upper surface of the substrate 10, the mounting and mounting of the LED chip 11 and A pad 12 on which wire bonding is made, an external electrode terminal 18 formed on a bottom surface of the substrate 10 and electrically connected to the pad 12, and an LED chip 11 on the pad 12. The lens unit 30 is molded so as to be sealed to emit light to the outside, and a reflective wall 38 provided at both sides of the lens unit 30 to reflect light.

In the LED package having such a structure, the upper surface of the substrate 10 is composed of a positive terminal and a negative terminal 13, 14, the pad 12 for chip bonding (Chip bonding) and wire bonding (Wire bonding) ) And a soldering pad or external electrode terminal 18 for board mounting is disposed on the bottom surface of the substrate 10. In addition, the plating layer 21 is formed on the inner circumferential surface of the through-hole 16 formed in the substrate 10.

Accordingly, the pad 12 disposed on the top surface of the substrate 10 and the external electrode terminal 18 disposed on the bottom surface may be electrically connected to each other.

In addition, the LED chip 11 is preferably mounted on an upper surface of the negative electrode terminal 14 and electrically connected to the terminals 13 and 14 by wires 22 and 24. Of course, it is also possible to mount the LED chip 11 on the positive electrode terminal (13).

The lens unit 30 is molded to a predetermined height on the upper surface of the substrate 10 to emit light emitted from the LED chip 11 to the outside.

The lens portion 30 has a convex lens shape by being formed in a rectangular cross-sectional shape having a semicircular shape at the top thereof. Therefore, the light emitted from the LED chip 11 can be efficiently emitted to the outside.

The lens unit 30 may be made of a transparent liquid resin, and this resin may be molded by a molding method.

That is, as will be described later, a mold (not shown) is disposed on the substrate 10, and the mold includes the pad 12 and the LED chip 11, and then the resin is preferably transparent. The lens unit 30 is molded by injecting and molding an epoxy resin.

In addition, when the lens unit is molded, a phosphor is injected, and when a blue LED chip is used, yellow phosphors are mixed to realize white light.

Therefore, since the lens unit 30 is formed long in the X-axis direction, and a narrow and convex curved surface is formed in the Y-axis direction, light emitted from the LED chip 11 can be efficiently collected.

On the other hand, the reflective wall 38 is protruded at a predetermined height on each side edge portion of the substrate 10 and are located at a predetermined distance from each other.

As described later, the reflective wall 38 is manufactured by a separate process and attached to the substrate 10 by an adhesive.

That is, the reflective wall 38 is formed by molding a synthetic resin, preferably a pure white epoxy resin, having high light reflectivity and high heat resistance.

And, as shown in Fig. 13, the reflective wall 38 has a symmetric trapezoidal bar shape whose height h2 is higher than the height h1 (Fig. 11) of the third quarter point 2 of the semicircular portion of the lens portion 30. Is preferred. In addition, the reflective wall 38 is formed to be longer than the width, the inclined surface 23 is formed on one side to reflect the light.

The reflective wall 38 manufactured by a separate process as described above is integrally attached to the substrate 10 by an adhesive. At this time, the adhesive is preferably an opaque pure white epoxy resin.

Therefore, the attached reflective wall 38 reflects the light emitted from the LED chip 11 and can more firmly protect the LED chip 11 as an outer wall of the package.

Such an LED package may be manufactured by a process as shown in FIG. 16. First, a substrate preparation step S100 is performed. In the step (S100), a plurality of lines arranged in the longitudinal direction of the plurality of circuit units 20 that can be included in one package is arranged in a plurality, and the printed circuit board 10 having sufficient edges on the outside of the arrangement is prepared.

As shown in FIGS. 8 and 9, the printed circuit board 10 has a predetermined size or more and a plurality of plated thru-holes 16 are formed. The through-hole 16 penetrates up and down the substrate 10.

In addition, a pad 12 for chip bonding and wire bonding is disposed on an upper surface of the substrate 10, and a soldering pad or external electrode terminal 18 for board mounting is disposed on a bottom surface of the substrate 10. . At this time, the plating layer 21 is formed on the inner circumferential surface of the through-hole 16.

Therefore, the pad 12 disposed on the top surface of the substrate 10 and the external electrode terminals 18 disposed on the bottom surface may be electrically connected to each other.

After the substrate having such a structure is prepared, as shown in FIGS. 9, 10, and 16, the LED chip mounting step S110 is performed. In this step, the LED chip 11 is mounted on the pad 12 and the wires 22 and 24 are bonded.

Then, the LED chip 11 is mounted on each of the negative electrode terminals 14, and the wires 22 and 24 provided on the LED chips 11 are bonded to the positive electrode terminal 13 and the negative electrode terminal 14, respectively. Done.

At this time, since the reflective wall 38 is formed on the substrate 10, the mounting work of the LED chip 11 is not prevented by the reflective wall 38.

Since the mounting work of the LED chip 11 is performed on a plurality of pads 12 disposed on the substrate 10 at a time, work efficiency may be improved.

After the process is completed, as shown in FIGS. 10, 11, and 16, the lens part molding process S120 is performed.

In the step S120, the convex lens-shaped lens unit 30 is formed by molding a transparent epoxy resin on the upper surface of the substrate 10.

That is, the plurality of circuit units 20 are arranged in a plurality of rows on the substrate 10, and the circuit units 20 forming the same row by arranging a template (not shown) on the substrate 10 are the same. It is included in the lens unit (32).

That is, the mold is disposed to have a width of a predetermined area W1 to include the pad 12 and the LED chip 11.

In this way, after the mold is disposed in the predetermined region W1, a plurality of lens parts 30 are simultaneously formed by injecting and molding a synthetic resin, preferably, a transparent epoxy resin and a phosphor.

In this case, the plurality of lens units 30 are formed to be spaced apart from each other by a predetermined distance to form a space D1 therebetween, and the reflective wall 38 (FIG. 12) is attached to the space D1 by an attachment method. Can be arranged.

In addition, by simultaneously molding the epoxy resin, the shape of the lens unit 30 may be shaped, and the cross-sectional shape of the lens unit 30 may be formed in a rectangular cross-section having a semicircle formed thereon, thereby providing a uniform directing pattern. Can be secured.

In addition, the lens unit 30 may form a light directing pattern as shown in FIG. 4B by forming the light in a wider direction in the X-axis direction and a narrower light in the Y-axis direction.

As described above, after the lens unit 30 is formed, as shown in FIGS. 12, 13, and 16, the reflective wall forming step S130 is performed.

In this step (S130), a reflective wall 38 for efficiently reflecting the light emitted from the LED chip 11 is formed. That is, after the plurality of lens units 30 are formed on the substrate, the reflective wall 38 is attached to the space D1 (FIG. 11) formed between the lens units 30.

The reflective wall 38 is formed by a separate process, preferably by a molding method.

That is, the reflective wall 38 is formed by injecting a plurality of molds having a trapezoidal cross section, and injecting a liquid synthetic resin, preferably a pure white opaque liquid epoxy, into the plurality of molds and curing them for a predetermined time.

The plurality of reflective walls 38 thus formed are attached to the space D1 formed between the lens units 30, respectively, by an adhesive.

At this time, the adhesive is preferably an opaque pure white epoxy resin, and is applied to a predetermined region (regions excluding W1 to W1 region) of the substrate 10.

The reflective wall 38 is attached to this area so that the reflective wall 38 is positioned on both sides of the lens portion 30.

Thus, the reflective wall 38 can more firmly protect the LED chip as the outer wall of the package together with the role of the reflective wall of the light emitted from the LED chip 11.

After forming the reflective wall 38 in this manner, as shown in Figs. 10, 12 and 16, the step (S140) of separating into separate packages is performed.

That is, the plurality of packages are separated from one substrate 10 by cutting the plurality of pads 12 and the LED chips 11 disposed on the substrate 10 for each individual package 20 (FIG. 9). .

In this case, each individual package is cut along the center line of the reflective wall 38 attached to each package 20 and the dividing line of the circuit unit 20 defining the length of the package. The cutting is performed with a sawing equipment.

At this time, the width of the saw blade can be adjusted to make the thickness of the reflective wall 38 thinner, so that the width of the package in one mold according to the width of the saw blade (where “width” is the package at the side mounting) Can be commercialized in various ways.

FIG. 14 illustrates a path of light emitted from the LED chip when power is applied to the side light emitting diode package manufactured through the above process.

As shown, when light is emitted from the LED chip 11, the emitted light is totally reflected by the reflective wall 38 in the sidewall section A in the vertical direction of the lens unit 30 and into the semicircle. Enter.

In the intermediate section B that is connected to the reflective wall 38, part of the light is emitted toward the package side according to the incident angle. In addition, in the upper section C of the semi-circular part, most of the light is emitted almost straight toward the package upward direction.

At this time, when the light emitted from the intermediate section B does not have the reflective wall 38, as shown in Fig. 15A, the Y-axis directional pattern is undesirably formed.

On the other hand, in the present invention, by installing the reflective wall 38 on the side of the lens 30, the package side-directed light emitted from the intermediate section (B) is corrected to be focused toward the upper package as shown in Fig. 15 (b) can do.

As described above, the light efficiency emitted from the LED chip 11 may be corrected to be focused upward in the course of passing through the lens unit 30 and the reflective wall 38.

As described above, the side-emitting diode package and its manufacturing method according to the preferred embodiment of the present invention have the following advantages.

First, the shape of the lens can be shaped by forming a lens by injecting and curing epoxy resin in a batch by a molding method on a printed circuit board on which a plurality of circuit units are arranged. Quality uniformity and reproducibility can be achieved.

Second, the light extraction efficiency is improved by the lens portion having a convex lens shape.

Third, higher luminance may be realized on the LCD screen with an efficient light directing pattern that greatly improves light incident efficiency and luminance uniformity in the LGP.

Fourth, after forming the lens of the molding method, it is possible to achieve an excellent productivity improvement by the ease of installing a separate reflective wall. It will greatly contribute to the commercialization of high-definition LCD using LED light source by improving the technical and economic environment of LED light source application.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it is within the scope of the present invention.

Claims (10)

A printed circuit board; A pad formed on an upper surface of the printed circuit board and formed of a positive electrode and a negative electrode terminal, the pad of which an LED chip is mounted and wire bonded; An external electrode terminal formed on a bottom surface of the printed circuit board and electrically connected to the pad; And LED package for an LED backlight light source is provided on both sides of the lens portion to reflect the light, the inclined surface is formed in the direction of the lens portion to reflect the light, the reflective wall attached by the adhesive method on the substrate. delete The LED package of claim 1, wherein the cross-sectional shape of the lens unit is a rectangular cross-section having a semicircular shape at an upper portion thereof. delete The LED package of claim 1, wherein the reflective wall has a height smaller than a height of the lens unit. Preparing a printed circuit board in which a plurality of circuit units are arranged in a row with each other, and an electrical connection is formed for each circuit unit; Mounting an LED chip on a pad of the printed circuit board and performing wire bonding; A lens part molding step of forming a plurality of LED chips arranged on the same line and an electrical connection along the plurality of arrangements of the circuit units to cover the electrical connections; After the step, arranging a reflective wall in a space formed between the plurality of lens units by an attachment method; And And cutting the printed circuit board to separate the respective packages. The method of claim 6, wherein in the lens unit molding step, manufacturing the LED package for the LED backlight light source for molding the lens unit by placing the mold along a plurality of arrays of the circuit unit, injecting and curing the resin and phosphor in the mold. Way. The method of claim 6, wherein the cross-sectional shape of the lens unit has a rectangular cross-sectional shape having a semi-circle shape on the top thereof. The method of claim 6, wherein in the forming of the reflective wall, the reflective wall is manufactured by a separate molding process. The method of claim 6, wherein when the blue LED chip is used as the LED chip in the lens unit forming step, the LED package for an LED backlight light source emits white light by injecting and mixing a yellow phosphor during molding the lens unit.

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