KR100849782B1 - Method for manufacturing led package - Google Patents

Abstract

A method for manufacturing an LED(Light Emitting Diode) package is provided to prevent the color variation due to a beam angle by using the sedimentation of fluorescent particles and the evaporation of a diluent to form a fluorescent layer uniformly. A fluorescent substance(107) is dispersed and a curable transparent polymer material(108) diluted by a diluent(111) is prepared. The curable transparent polymer material is injected into a mounting space on which an LED chip(105) is mounted to coat the LED chip. The fluorescent substance dispersed in the injected transparent polymer is sedimented. After the fluorescent substance is sedimented, the diluent in the mounting space is evaporated to form a fluorescent layer arranged along a surface of the LED chip. After the fluorescent layer is formed, a transparent package resin covering the fluorescent layer is formed. Before the transparent polymer is coated on the LED chip, the LED chip is mounted on a bottom section of a reflective cup of a package body. In the coating process of coating the transparent polymer on the LED chip, the transparent polymer is injected into the reflective cup.

Description

Method for Manufacturing LED Package {Method for Manufacturing LED Package}

1 is a cross-sectional view illustrating a manufacturing process of an LED package according to a conventional example.

2 is a cross-sectional view illustrating a manufacturing process of an LED package according to another conventional example.

3 is a schematic cross-sectional view of the LED package obtained by the manufacturing method of FIG.

4A to 4F are cross-sectional views illustrating a manufacturing process of the LED package according to the embodiment of the present invention.

5 is a cross-sectional view illustrating a manufacturing process of the LED package according to another embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

101: package body 101a: reflection cup

101b: recess 102a, 102b: lead frame

105: LED chip 106: bonding wire

107: phosphor 108: transparent polymer

110: phosphor film 111: diluent solvent

118: transparent packaging resin

The present invention relates to a method of manufacturing a light emitting diode (LED) package, and more particularly, to a method for manufacturing an LED package which prevents color deviation according to a directivity angle, implements uniform product characteristics, and facilitates a manufacturing process.

Recently, LEDs are used as light sources of various colors. As the demand for high power and high brightness LEDs, such as white LEDs for lighting, increases, studies are being actively conducted to improve the performance and reliability of LED packages. In order to improve the performance of the LED products, together with the LED chip itself having excellent light efficiency, the LED package must be secured at the same time to effectively extract light, excellent color purity and uniform characteristics between the products.

In order to obtain white light using an LED, a phosphor (for example, a yellow phosphor, etc.) is usually disposed on a blue or ultraviolet LED chip. The quality of this white light is greatly influenced not only by the characteristics of the phosphor itself to be applied, but also by the distribution form of the phosphor. In traditional LED package processes in which a mixture of transparent resin and phosphor powder is injected into a cup of a package on which an LED chip is mounted, it is quite difficult to control the spatial distribution of phosphors in the resin encapsulant. As a result, the color temperature deviation of the output light is severe, and color separation or color staining is likely to occur.

In order to solve this problem, U.S. Patent No. 7,049,159 proposes a conformal mapping method for distributing phosphors at high density along the surface of an LED chip. In the case of such conformal mapping, the light efficiency is greatly increased. In addition, color separation due to the emission angle may also be lowered. However, since the LED chip type or the chip mounting method to which the conventionally proposed conformal mapping method can be applied is very limited, there is a limitation that it cannot cope with all kinds of LED chip mounting types. These problems occur not only in white LED packages, but also in other LED packages (eg, LED packages that output pink light) using phosphors.

1 is a cross-sectional view illustrating a conventional LED package manufacturing process. Referring to Fig. 1 (a), a package main body having a reflection cup 11a and a lead frame 12a and 12b inserted therein is prepared. As shown in Fig. 1 (b), The blue LED chip 15 is mounted on the bottom of the reflecting cup 11a, and the LED chip 15 and the lead frames 12a and 12b are connected by a wire 15 or the like. As shown, a transparent resin 18 such as epoxy in which the yellow phosphor 17 is dispersed is injected into the reflecting cup to seal the LED chip 15 and to cure the resin 18 by heating.

However, according to the above process, the phosphor 17 having a high specific gravity is settled until the transparent resin 18 is cured, and thus the phosphor 17 is unevenly distributed (Fig. 1 (c). When the chip 15 is turned on, color separation or color staining occurs depending on the emission angle, and color uniformity of output light is reduced, and the spatial distribution of the phosphor 17 varies from product to product, resulting in inferior property uniformity among LED package products. Since only the phosphor near the surface of the LED chip 15 is effective for white light conversion, and the phosphor at the bottom of the reflecting cup 11a or the portion away from the surface of the chip acts as a light diffusing or light absorbing material, it is manufactured by the above process. LED packages have a relatively low light efficiency.

2 is a cross-sectional view illustrating a white light LED package manufacturing process according to another conventional example. Referring to FIG. 2 (a), after mounting the LED chips 25 on the substrate 21, a stencil having holes 8 so that openings 8 align with the LED chips 25. 23 is disposed on the substrate 21. Thereafter, as shown in Fig. 2B, a light-transmitting resin material containing phosphors is injected into the hole. Then, as shown in Fig. 2C, the stencil 23 is removed to form the phosphor film 28 disposed along the surface of the LED chip 25, and then the phosphor film 28 by heating or the like. Harden. After curing of the phosphor film 28, the substrate 21 is cut along the cutting line L to separate the LEDs into individual elements.

According to the conformal mapping method as shown in FIG. 2, since white light (output light) is emitted only near the surface of the LED chip 25, application of secondary optics is easy and color according to a direction angle There is almost no deviation. However, the mounting method of the LED chip to which such a conformal mapping method can be applied is very limited. That is, as shown in FIG. 3, when the LED chip 25 in the package 20 is a flip-chip type LED, manufacturing of the LED package by the conformal mapping method is suitable, but the wire This method is difficult to apply in the case of LED chip protruding. In addition, the above-described process of FIG. 2 must be performed in a fab to ensure its quality. When only the packaging process is performed by sourcing the LED chip, the above-described conformal mapping method cannot be applied. In FIG. 3, reference numerals 25a and 25b denote electrodes (n-electrodes and p-electrodes) of the LED chip 25, reference numerals 31 and 32 denote bumps or solders, and reference numerals 21a and 21b denote substrates 21. The connection pad formed on the top is shown.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide high product uniformity and light efficiency, to suppress color spots or color separation due to uneven distribution of phosphors, and to be independent of the shape of a package or a chip. To provide a highly versatile LED package manufacturing method.

In order to achieve the above technical problem, the present invention comprises the steps of preparing a curable transparent polymer material in which the phosphor is dispersed and diluted with a diluent; Coating the LED chip by injecting the transparent polymer material into a mounting space in which the LED chip is mounted; Sedimenting the injected phosphor in the injected transparent polymer material; After sedimentation of the phosphor, a diluent in the mounting space is evaporated to form a phosphor film closely disposed along the surface of the LED chip.

According to an embodiment of the present invention, the LED package manufacturing method may further include forming a transparent packaging resin covering the phosphor film after forming the phosphor film.

According to an embodiment of the present invention, before the LED chip coating step of the transparent polymer material, the LED chip is mounted on the bottom of the reflective cup of the package body having a reflective cup, and in the LED chip coating step of the transparent polymer material The transparent polymer material may be injected into the reflective cup.

According to another embodiment of the present invention, before the LED chip coating step of the transparent polymer material, the LED chip is disposed on a substrate inside a dam that provides an accommodation space of the transparent polymer material, In the LED chip coating step, the transparent polymer material may be injected into the dam. In this case, a plurality of LED chips may be mounted inside the dam. The method may further include removing the dam after the phosphor film is formed.

The transparent polymer material may be selected from at least one of silicone resin, polyvinyl alcohol, polyacrylamide, polyethylene imine, polyvinyl pyrrolidone, methyl cellulose and ethyl cellulose.

The diluent may be a volatile organic material. The diluent may be selected from at least one of alcohol and acetone. In the evaporation step of the diluent, the diluent may be evaporated at room temperature or by heating.

The LED package manufacturing method can be applied to the manufacture of a white LED package. A white LED package can be implemented by selecting a blue LED chip or an ultraviolet LED chip and an appropriate phosphor (including a mixture of two or more phosphors).

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

4A to 4F are cross-sectional views illustrating a method of manufacturing an LED according to an embodiment of the present invention.

Referring to FIG. 4A, a package body 101 having a reflective cup 101a and inserted with lead frames 102a and 102b is provided. The concave portion 101b is formed in the upper portion of the package body 101 by the reflecting cup 101a to provide a mounting space for the LED chip. An inner reflective wall 101a may be coated with a separate reflective metal film (eg, Ag film) in order to increase the reflectance of light. Thereafter, as shown in FIG. 4B, the LED chip 105 is mounted on the bottom of the reflecting cup 101a, and the lead frames 102a and 102b and the LED chip ( 105) is electrically connected. Instead of the lead frames 102a and 102b, a conductive pattern formed on the bottom of the reflective cup 101a may be used. In addition, the LED chip 105 may be mounted on the package body 101 using flip-chip bonding instead of wire bonding.

Thereafter, as shown in FIG. 4C, the phosphor 107 is dispersed and the curable transparent polymer material 108 or the transparent polymer diluted by the diluent 111 is injected into the reflecting cup of the package body 101. . Accordingly, the (diluted) transparent polymer material 108 containing the phosphor 107 is applied to the chip in the mounting space of the LED chip 105. The diluted transparent polymer material 108 containing the phosphor 107 may be prepared in advance before the LED chip mounting step (FIG. 4B) or before the formation of the package body (FIG. 4A), and after the chip mounting or the package body It may be prepared after formation.

As the LED chip 105 and the phosphor 107 used, for example, to implement a white LED, a blue LED chip and a yellow phosphor may be used. In addition, a combination of a blue LED chip and a mixture of green and red phosphors or a combination of an ultraviolet LED chip and a mixture of red, green and blue phosphors may be used. In addition, since the present invention can be applied to an LED package (for example, a pink light LED package) for obtaining other output light in addition to the white LED, the LED chip 105 and the phosphor 107 used in the present invention are particularly limited. It is not. In addition, the present invention may be generally applied to any form or method such as' wire bonding ', flip chip bonding', and 'combination of die bonding and wire bonding' with respect to the shape or mounting method of the LED chip 105.

As the transparent polymer material 108, a silicone resin conventionally used as a resin encasulant may be used, in addition to other curable transparent polymer materials such as polyvinyl alcohol, polyacrylamide, polyethylene imine, polyvinyl Pyrrolidone, methyl cellulose or ethyl cellulose and the like can be used.

As the diluent 111, a volatile organic material which is easily evaporated at room temperature may be used, or an organic material which is evaporated by heating may be used. The diluent 111 has a lower viscosity than the transparent polymer material 108 and sufficiently lowers the viscosity of the entire diluted polymer material 108, 111 solution by mixing with the transparent polymer material 108. The viscosity of the whole diluted polymer material 108, 111 solution may vary depending on the phosphor used, but preferably has a value low enough to facilitate settling of the phosphor. As such a diluent 111, alcohol or acetone, such as methanol and ethanol, can be used, for example. By using a solution of the transparent polymer materials 108 and 111 diluted by the diluent 111, the phosphor 107 dispersed in the material can be more effectively settled. Therefore, in the present invention, unlike the conventional phosphor-containing resin encapsulant, the sedimentation of the phosphor is promoted to intentionally induce a nonuniform distribution of the phosphor (a concentrated distribution of the phosphor at the surface of the LED chip 105 and the bottom of the reflecting cup). To induce.

After injection of the diluted transparent polymer material in which the phosphor is dispersed, as shown in FIG. 4D, the phosphor particles 107 in the transparent polymer material are allowed to settle to the bottom as shown in FIG. 4D. Accordingly, the phosphors are distributed in a relatively high density on the surface of the LED chip 105 and the bottom of the reflecting cup other than the portion where the LED chip 105 is mounted.

Then, as shown in FIG. 4D, a diluent such as alcohol or acetone is evaporated to form the phosphor film 110 coated on the surface (top and side) of the LED chip 105 and the bottom of the reflecting cup. The phosphor film 110 contains phosphor particles 107 at a high density, and the transparent polymer material 108 serves as a matrix material or a binder material of the phosphor film 110. The diluent may be left to evaporate in nature or evaporated by relatively low temperature heating. If the diluent consists of volatile organic substances with high vapor pressure, it can evaporate in a short time even at room temperature without heating.

In addition, by heating a transparent polymer material such as a silicone resin and curing it, the phosphor film 110 may be cured or solidified in a fixed form. The heating of the transparent polymeric material may be carried out at a temperature higher than the evaporation temperature of the diluent. For example, the diluent may be evaporated at a temperature of 50-60 ° C. and the transparent polymer material may be cured at a temperature of 100 ° C. or more.

According to the present embodiment, since wavelength conversion is performed through the phosphor film 110 formed along the surface of the LED chip 105, there is almost no color deviation or color spot according to the orientation angle, and light having uniform characteristics You can print The amount of light loss caused by the phosphor is also reduced. In addition, since the phosphor film coated conformally along the LED chip surface can be easily formed by phosphor settling and diluent evaporation, a conventional conformal mapping method (see the phosphor film forming process of FIG. 2 using a stencil). Compared with the phosphor film forming process is easier.

In addition, compared with the case of using a simple injecting process of the phosphor-containing resin encapsulant (see FIG. 1), the present embodiment provides an advantage that the color temperature control can be easily controlled by the absolute amount of the phosphor. That is, in the conventional phosphor, the phosphor is entirely unevenly distributed in the resin encapsulant, whereas in the present embodiment, since the phosphor particles are present at high density only on the bottom surface of the reflecting cup and the LED chip due to the phosphor settling, the transparent polymer material 108 Irrespective of the amount of the diluent 111 and the diluent 111 may be used by mixing the absolute amount of the desired phosphor with the injection solution. As a result, color deviation and characteristic deviation between LED package products are reduced.

In addition, the present LED package manufacturing process can be applied to the shape of the package and the mounting method of the LED chip (flip chip bonding, wire bonding, etc.). The interference caused by the wire hardly occurs. That is, the fall of the electrical characteristic and the optical characteristic by the fluorescent substance attached to or located in the wire is suppressed (compared with FIG. 1). Therefore, the selection range of the applicable LED chip also becomes wider.

Although the resultant formed with the phosphor film 110 may be used as an LED package, a transparent packaging resin 118 for wrapping (or covering) the phosphor film 110 may be further formed as shown in FIG. 4F. For example, a silicone resin or an epoxy resin may be injected into the reflective cup and cured to encapsulate the LED chip 105 coated with the phosphor film 110. In addition, a secondary optical system member such as a hemispherical lens may be further disposed on the transparent packaging resin 118 (or on the package body 101 without the transparent packaging resin 118). The transparent packaging resin itself may be manufactured in the form of a lens, such as by making the top surface of the transparent packaging resin into a hemispherical shape.

5 is a cross-sectional view illustrating a LED package manufacturing process according to another embodiment of the present invention.

As shown in FIG. 5A, at least one LED chip 105 is mounted on the substrate 101 to form a dam 103 that provides an accommodation space of the transparent polymer material. The portion surrounded by the dam 103 is provided to the mounting space of the LED chip 105 (thus, the LED chip 105 is mounted inside the dam 103). The LED chip 105 may be connected to the substrate wiring (not shown) by the wire 106. Alternatively, the LED chip may be mounted in a flip chip method without wires.

Then, as shown in FIG. 5 (b), in the inside of the dam 103 (ie, the mounting space of the LED chip 105), the 'phosphor 107 as described above is dispersed and the diluent 111 is dispersed. Inject the transparent polymer material 108 'diluted with Accordingly, the transparent polymer material 108 covering the LED chip 105 is disposed in the mounting space inside the dam 103.

Next, as shown in FIG. 5C, the phosphor 107 is allowed to stand for a predetermined time to settle the phosphor 107 onto the surface of the LED chip 105 and the upper surface of the substrate exposed from the LED chip 105. After the phosphor 107 is sufficiently settled, as shown in FIG. 5 (d), the diluent 111 is evaporated by heating or at room temperature to form the phosphor film 110 in which the phosphor is distributed at a high density. The phosphor film 110 is conformally formed along the surface of the LED chip 105 and can cure the transparent polymer material 108 by additional heat supply. After the phosphor film 110 is completed, the LEDs may be separated by individual devices by removing the dam 103 and cutting the substrate 101 along the cutting line L. FIG. Alternatively, the LED package may be used in a state including a plurality of LED chips without cutting the substrate after the phosphor film 110 is formed.

In addition, after the phosphor film 110 is formed by diluent evaporation, a transparent packaging resin 118 may be further formed to cover the phosphor film 1100 without removing the dam 103. The transparent packaging resin 118 may be a lens as necessary. It is also possible to form an additional optical member such as a lens on the transparent packaging resin 118 or on the package body 110.

It is intended that the invention not be limited by the foregoing embodiments and the accompanying drawings, but rather by the claims appended hereto. In addition, it will be apparent to those skilled in the art that the present invention may be substituted, modified, and changed in various forms without departing from the technical spirit of the present invention described in the claims.

As described above, according to the present invention, it is possible to easily form the phosphor film uniformly formed along the surface of the LED chip by using the sedimentation of the phosphor particles and the evaporation of the diluent. Therefore, it is possible to prevent the color deviation according to the directivity angle in the product, to improve the luminous efficiency, and to reduce the characteristic deviation between the LED products. In addition, the process according to the present invention is applicable to various package and LED chip types, and the choice of mounting method is very wide.

Claims (15)

Preparing a curable transparent polymer material having phosphors dispersed therein and diluted with a diluent; Coating the LED chip by injecting the transparent polymer material into a mounting space in which the LED chip is mounted; Sedimenting the injected phosphor in the injected transparent polymer material; And After depositing the phosphor, evaporating a diluent in the mounting space to form a phosphor film disposed along the surface of the LED chip. The method of claim 1, After the forming of the phosphor film, the method for manufacturing a LED package, characterized in that it further comprises the step of forming a transparent packaging resin covering the phosphor film. The method of claim 1, Before the LED chip coating step of the transparent polymer material, the LED chip is mounted on the bottom of the reflective cup of the package body having a reflective cup, In the LED chip coating step of the transparent polymer material, the transparent polymer material is injected into the reflecting cup LED package manufacturing method characterized in that. The method of claim 1, Before the LED chip coating step of the transparent polymer material, the LED chip is disposed on a substrate inside the dam that provides an accommodation space of the transparent polymer material, In the LED chip coating step of the transparent polymer material, the transparent polymer material is an LED package manufacturing method, characterized in that injected into the dam. The method of claim 4, wherein Before the LED chip coating step of the transparent polymer material, the LED package manufacturing method, characterized in that a plurality of LED chips are mounted inside the dam. The method of claim 4, wherein After the phosphor film is formed, the LED package manufacturing method characterized in that it further comprises the step of removing the dam. The method of claim 1, The transparent polymer material is at least one selected from silicone resin, polyvinyl alcohol, polyacrylamide, polyethylene imine, polyvinyl pyrrolidone, methyl cellulose and ethyl cellulose. The method of claim 1, The diluent is a LED package manufacturing method, characterized in that the volatile organic material. The method of claim 1, The diluent is an LED package manufacturing method, characterized in that at least one selected from alcohol and acetone. The method of claim 1, In the evaporation step of the diluent, the diluent is a LED package manufacturing method, characterized in that evaporated at room temperature. The method of claim 1, In the evaporation step of the diluent, the diluent is heated, characterized in that the LED package manufacturing method. delete The method of claim 1, The combination of the LED chip and the phosphor is selected to output white light, The LED chip is a blue LED chip, the phosphor comprises a yellow phosphor, characterized in that the LED package manufacturing method. The method of claim 1, The combination of the LED chip and the phosphor is selected to output white light, The LED chip is a blue LED chip, wherein the phosphor comprises a mixture of green and red phosphors. The method of claim 1, The combination of the LED chip and the phosphor is selected to output white light, The LED chip is an ultraviolet LED chip, wherein the phosphor comprises a mixture of blue, green and red phosphors.

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