KR100634189B1 - Thin light emitting diode package and method for manufacturing the same - Google Patents

Abstract

A thin light emitting diode package and its manufacturing method are provided to increase luminance and to decrease an operational voltage by using a lead frame having a reflective cup. A plate-shaped lead frame(101) whose center is bent has a reflective cup(104). An LED chip(106) is mounted on a bottom of the reflective cup. A molding unit packs the LED chip and the lead frame to expose a lower surface of the bottom of the reflective cup to release heat generated in the LED chip. The lead frame is exposed to an outside from the molding unit so that both ends of the lead frame form connecting terminals with outside circuits. The molding unit includes an inner molding unit(108) and an outer molding unit(110). The inner molding unit is formed in the reflective cup to pack the LED chip. The outer molding unit is formed at the outside of the inner molding unit to pack the lead frame.

Description

Thin film type light emitting diode package and its manufacturing method {THIN LIGHT EMITTING DIODE PACKAGE AND METHOD FOR MANUFACTURING THE SAME}

1 is a cross-sectional view of a light emitting diode package according to the prior art.

2 is a cross-sectional view of a thin film type light emitting diode package according to an embodiment of the present invention.

3 is a plan view of the thin film LED package of FIG. 2.

4 is a cross-sectional view of a thin film type light emitting diode package according to another embodiment of the present invention.

5 is a plan view of the thin film diode package of FIG. 4.

6 is a cross-sectional view of a thin film type light emitting diode package according to another embodiment of the present invention.

7A to 7G are cross-sectional views illustrating a method of manufacturing a thin film type LED package according to an embodiment of the present invention.

8 is a plan view illustrating the leadframe array after the second bending step is completed.

9 is a cross-sectional view showing a state in which a Zener diode is mounted on a lead frame in the method of manufacturing a thin film type light emitting diode package according to another embodiment of the present invention.

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

100, 200, 300: thin film light emitting diode package

101: lead frame 101a: first lead portion

101b: second lead portion 101c: separation portion

102: bottom of the reflecting cup 103a, 103b: terminal

104: reflecting cup 104a: reflecting surface

106: LED chip 107: bonding wire

108: inner molding part 110: outer molding part

120: Zener Diode

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode package and a method for manufacturing the same, and more particularly, to a thin film type light emitting diode package and a method for manufacturing the same, which have excellent heat dissipation characteristics and are suitable for miniaturization.

Recently, light emitting diodes (LEDs) using compound semiconductor materials such as GaN-based semiconductors have been developed to realize light emitting sources of various colors. The electro-optical characteristics of LED products are primarily determined by the compound semiconductor materials used in the LED chips and their structure, but are also greatly influenced by the structure of the package for mounting the LED chips as secondary elements.

In general, a lot of heat is generated during the operation of the LED chip. Heat generated from the LED chip must be released to the outside. If the heat is not released sufficiently, the temperature rises, the luminous efficiency is lowered and the lifetime is shortened. In particular, in packages using high power or high brightness light emitting diode chips, efforts have been made to effectively release heat generated from LED chips.

In addition, with the trend toward miniaturization and light weight of electronic components, there is an increasing demand for thin film type LED packages having a very thin thickness. For example, LED packages used for flashes for camera phones need to be manufactured in a thin film type for miniaturization of flashes. However, the LED package employ | adopted in the prior art does not fully satisfy such a requirement, and has a problem that a manufacturing process is difficult.

1 is a cross-sectional view showing a schematic structure of a conventional LED package 10. Referring to FIG. 1, the LED package 10 includes a substrate 11, a reflector 13, and an LED chip 16. The LED chip 16 is mounted on the bottom of the reflecting frame 13 and electrically connected to the two lead electrodes 14 and 15 through the bonding wire 17. The molding resin 18 which encloses the LED chip 16 is apply | coated in the reflection frame 13. The molding resin 18 may be dispersed with a wavelength conversion phosphor (eg, a YAG phosphor).

The substrate 11 and the reflecting frame 13 may be made of a ceramic material to increase heat dissipation characteristics. However, even when the substrate 11 and the reflecting frame 13 are formed of a ceramic material, the heat generated from the LED chip (particularly in the high output LED chip) cannot be effectively released. As a result, the luminous efficiency and life may be reduced. In addition, since the LED package 10 includes a reflective frame 13 and a substrate 11 separately from the lead frames 14 and 15, the overall thickness is considerably large and a thin film type LED package having a thickness of several hundred micrometers or less. It is difficult to implement.

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 a thin film type LED package which effectively dissipates heat generated from an LED chip and has a thinner thickness.

In addition, another object of the present invention is to provide a method for manufacturing a thinner LED package having excellent heat dissipation characteristics with a thinner thickness.

In order to achieve the above technical problem, the thin film type light emitting diode package according to the present invention, the plate-shaped lead frame is bent at the center portion to have a reflection cup; An LED chip mounted on the bottom of the reflecting cup; And a molding part encapsulating the LED chip and the lead frame to expose the bottom surface of the reflective cup bottom. In addition, the lead frame is bent to the lower portion of the molding portion outside the upper end of the reflecting cup and extends laterally at both ends.

According to the embodiment of the present invention, both ends of the lead frame extending in the lateral direction may form terminals connecting to an external circuit. In this case, lower ends of both ends of the lead frame are exposed to the outside from the molding part.

According to an embodiment of the present invention, the molding part includes an inner molding part formed inside the reflecting cup to encapsulate the LED chip; It may include an outer molding portion formed on the outside of the inner molding portion to seal the lead frame. Phosphors for changing the light emitted from the LED chip may be dispersed in the inner molding part. For example, a white light emitting diode package may be implemented by dispersing a yellow phosphor in the inner molding part and using a blue LED chip as the LED chip.

According to an exemplary embodiment of the present invention, the lead frame may include a first lead portion having a reflective cup and a second lead portion disposed separately from the first lead portion.

According to an embodiment of the present invention, the thin film type light emitting diode package may further include a zener diode connected in parallel with the LED chip. In this case, the zener diode may be mounted on the outer surface of the upper end of the reflective cup.

In order to achieve the another object of the present invention, a method of manufacturing a thin film type light emitting diode package according to the present invention comprises the steps of preparing a metal plate for the lead frame; Bending the central portion of the metal plate to form a flat ridge; Bending the inside of the ridge to form a reflection cup to obtain a lead frame; Mounting an LED chip on the bottom of the reflecting cup; Encapsulating the LED chip and the lead frame with a molding resin to expose the bottom surface of the reflective cup.

According to an exemplary embodiment of the present disclosure, the encapsulation step may be performed such that both bottom surfaces of the lead frame are exposed to the outside from the molding resin. The both ends may be exposed to the outside to form a terminal connected to an external circuit.

According to an embodiment of the present invention, the encapsulation step includes: a first encapsulation step of applying a molding resin to the reflection cup to encapsulate the LED chip; It may include a second encapsulation step of forming a molding resin to encapsulate the lead frame. In this case, in the first encapsulation step, a molding resin in which phosphors are dispersed may be applied.

According to the exemplary embodiment of the present invention, the lead frame may be configured to include a first lead portion having a reflective cup and a second lead portion disposed separately from the first lead portion.

According to an embodiment of the present invention, before the encapsulation step, the method may further include mounting a zener diode to be connected in parallel with the LED chip. In this case, the zener diode may be mounted on the outer surface of the upper end of the reflective cup.

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.

2 is a cross-sectional view schematically illustrating a thin film type LED package according to an embodiment of the present invention, and FIG. 3 is a plan view of the LED package of FIG. 2. 2 is a cross-sectional view taken along the line XX ′ of FIG. 3. Referring to FIGS. 2 and 3, the thin film type LED package 100 includes a bent plate-shaped lead frame 101, an LED chip 106, and molding parts 108 and 110. The lead frame 101 is made of a metal material, and the molding parts 108 and 110 use a resin such as a silicone resin or an epoxy resin as a main material. As the LED chip 106, LEDs of any emission wavelength such as blue, green or red can be used. The lead frame 101 made of metal is composed of two lead portions 101a and 101b separated from each other by the separating portion 101c so as to provide terminals having different polarities.

2 and 3, the center portion of the lead frame 101 is bent to have the reflective cup 104. The LED chip 106 is mounted inside the reflecting cup 104 and is electrically connected to the respective lead portions 101a and 101b through the bonding wire 107. In particular, in this actual room form, one lead portion 101a forms a reflecting cup 104, and the other lead portion 101a is separated from the upper end of the reflecting cup 104. The inner surface of the reflecting cup 104 becomes the reflecting surface 104a for reflecting upward the light emitted from the LED chip 106. The luminance may be increased by the reflecting surface 104a of the reflecting cup 104. Although the planar shape of the reflective cup 104 is circular in FIG. 3, the present invention is not limited thereto. For example, a reflective cup having a rectangular planar shape may be used.

In addition, the bottom surface 102 of the reflective cup 104 is exposed to the outside from the molding part 110. Thus, heat generated in the LED chip 106 can be easily released to the outside through the bottom 102 of the reflecting cup 104. In particular, since the heat generated by the LED chip 104 is directly received at the bottom 102 of the reflecting cup 104 where the LED chip 106 is die-bonded, the heat dissipation effect through the exposed bottom surface of the reflecting cup bottom 102. Is remarkable. In this regard, the reflecting cup bottom 102 serves as a good heat dissipation ground.

In addition, the lead frame 101 is bent back to the lower part of the molding part 110 at the outer side of the upper end of the reflective cup 104 and extend laterally at both ends. In this way, the lead frame 101 is bent outside the upper end of the reflective cup 104, so that the molding resin squeezes out below the bent portion. Accordingly, the lead frame 101 and the molding part 110 are firmly coupled and the peeling phenomenon between the lead frame 101 and the molding part 110 is suppressed.

Unlike the related art, the LED package 100 does not include a separate substrate or a reflection frame (see FIG. 1). Instead, the reflecting cup is implemented by the bent portion of the leadframe, and the LED chip 106 is die-bonded on the leadframe 101. Accordingly, the LED package 100 may be manufactured very thinly compared to a conventional LED package using a ceramic or PCB substrate. For example, it can be manufactured in a thin package having a thickness of 0.8 mm (800 μm), which is very useful for miniaturization and light weight of LED products.

Both ends of the lead frame 101 extending in the lateral direction are exposed at the lower ends of both ends thereof so as to be connected to an external circuit (for example, wiring of an external circuit board). Accordingly, the exposed both ends form positive and negative terminals 103a and 104b for connection with an external circuit. The LED package 100 can be easily surface mounted through these terminals 103a and 104b.

As shown in FIG. 2, in the present embodiment, the molding parts 108 and 110 are divided into two parts, the inner molding part 108 and the outer molding part 110. The inner molding part 108 is coated inside the reflecting cup 104 to encapsulate the LED chip 106, and the outer molding part 110 encapsulates the entire lead frame 101 including the inner molding part 108. have.

In particular, the inner molding part 108 is formed of a transparent resin in which color conversion phosphors are dispersed to form a color conversion layer. For example, in order to implement a white light emitting device, the YAG-based yellow phosphor and a silicone resin may be mixed to form an inner molding part 108 and a blue LED may be used as the LED chip 106. The outer molding part 110 serves to protect and support the entire structure including the lead frame 101 and the bonding wire 107. The outer molding part 110 may be formed of, for example, an epoxy molding resin (EMC).

In the present embodiment, phosphors are dispersed in the inner molding part 108, but the present invention is not limited thereto. For example, in order to obtain light of simple red, green or blue light instead of white light, the inner molding part 108 may be formed of only a transparent resin (without phosphor).

Furthermore, the entire molding part may be formed of one molding part without distinguishing between the inside and the outside. An example of this is shown in FIG. 6. Referring to FIG. 6, the entire molding part is one molding part 110. The molding part 110 is formed of a transparent resin without a phosphor. The LED package 300 shown in FIG. 6 may be particularly useful when it is desired to obtain monochromatic light emission of blue, green, or red light without color conversion.

4 is a cross-sectional view illustrating a thin film type LED package according to another embodiment of the present invention, and FIG. 5 is a plan view of the LED package of FIG. 4. In this embodiment, the LED package 200 has a zener diode 120 connected in parallel with the LED chip 106. Other than that is the same as that of the LED package 100 of embodiment mentioned above. 4 and 5, the zener diode 120 is mounted on the top outer surface of the reflective cup 104 and electrically connected to the lead portion 101a through the bonding wire 127. The arrangement and connection of such a zener diode is merely an example, and any arrangement and connection that can be connected in parallel with the LED chip 106 can be adopted.

The zener diode 120 connected in parallel with the LED chip 106 protects the chip 106 from sudden voltage application, such as electrostatic discharge (ESD). Therefore, by mounting the Zener diode 120, the ESD voltage resistance of the LED package 200 is greatly improved. As a result of the measurement, it was confirmed that the ESD breakdown voltage was about 20 kV or more in the human body model and about 5 kV or more in the machine model by the parallel connection of the zener diode 120.

Hereinafter, a thin film type LED package manufacturing process according to an embodiment of the present invention will be described with reference to FIGS. 7A to 7G.

First, referring to FIG. 7A, a metal plate for lead frame is prepared. This metal plate consists of two lead parts 101a and 101b separated by the separating part 101c. Preferably, the metal plate may be provided in an array form so that multiple leadframes can be obtained simultaneously (and thus multiple LED packages can be obtained simultaneously) (see FIG. 8).

Next, as shown in FIG. 7B, the center portion of the metal plate is bent to form a flat ridge (first bending step). By forming the ridge as described above, it is possible to prevent the peeling phenomenon between the molding resin and the lead frame, which may be generated after the package is implemented later, in the photograph. Then, as shown in Fig. 7C, the inside of the ridge is bent to obtain a cup shape. (Second bending step). Accordingly, the lead frame 101 having the reflection cup 104 is obtained. The bottom 102 of the reflecting cup 104 is relatively flat as the part where the LED chip is seated. In this way, the bending frame is subjected to two times to obtain the lead frame 101 according to the present invention.

8 is a plan view illustrating the leadframe array after the second bending step for forming the reflective cup 104 is completed. Referring to FIG. 8, a plurality of lead frames in which the reflection cup 104 is formed is arranged to form an array 500, that is, an arrangement. Such leadframe arrays are obtained from metal plates provided in the form of arrays. After a molding step, by trimming the metal plate along the cutting lines L1 and L2 shown in FIG. 8, separate individual leadframes (or separate individual LED packages) may be obtained. By using such an array, multiple LED packages can be obtained simultaneously.

Next, as shown in FIG. 7D, the LED chip 102 is mounted on the bottom 102 of the reflection cup 104. At this time, each electrode (p-side electrode and n-side electrode) of the LED chip 102 is electrically connected to the corresponding lead portions 101a and 101b of the lead frame 101 by using a bonding wire. In this embodiment, the lead frame and the LED chip are connected using a bonding wire, but the present invention is not limited thereto. For example, the LED chip 106 can be electrically connected to the lead frame by flip chip bonding. In this case, the leadframe may have a separator at the bottom of the reflecting cup.

Next, as illustrated in FIG. 7E, the inner molding part 108 is formed by applying a transparent resin (silicon resin, etc.) in which phosphors are dispersed in the reflection cup 104 (first encapsulation step). The inner molding part 108 serves as a color conversion layer for converting the emitted light of the LED chip 106 into wavelength.

Then, as illustrated in FIG. 7F, the outer molding part 110 is formed of an epoxy molding resin to encapsulate the lead frame 101 (second encapsulation step). When forming the outer molding 110, it is important to expose the bottom surface 102 of the reflective cup 104 from the molding resin. As described above, by exposing the bottom 102 of the reflective cup 104, the bottom 102 can be made a heat radiation ground, and the heat dissipation effect can be maximized. In addition, lower surfaces of both ends of the lead frame 101 are exposed from the molding resin 110. As such, both ends of the lead frame 101 are exposed to form both terminals 103a and 103b connected to an external circuit.

Thereafter, as shown in FIG. 7G, the metal plate portion which protrudes unnecessarily from the molding part 110 is cut off and removed (see lines L1 and L2 in FIG. 8). As a result, a thin film LED package is obtained. At this time, both ends 103a and 103b of the lead frame form terminals having different polarities. This terminal can be easily connected to the wiring of an external circuit board.

In the above embodiment, in the first encapsulation step, that is, the inner molding part 108 forming step, a transparent resin in which phosphors are dispersed is used. However, when it is desired to realize monochromatic light emission such as blue or red instead of white light emission, the inner molding part 108 may be formed of a transparent resin in which phosphors are not dispersed. It is also possible to form all moldings in one step using only one type of molding resin without performing the encapsulation step in two steps (see Fig. 6).

In the above embodiment, no Zener diode is mounted. However, as shown in FIG. 9, before the encapsulation step, the zener diode 120 may be mounted on the lead portion 101b and connected in parallel with the LED chip 106 using a bonding wire 127 or the like.

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, by using the lead frame having the reflecting cup exposed from the molding part, not only can the brightness be increased and the operating voltage can be lowered, but also the heat dissipation effect is remarkably improved. As a result, the product performance and lifespan are greatly improved.

In addition, the molding resin sticks out below the bent portion of the lead frame, thereby preventing the peeling phenomenon between the lead frame and the molding portion. Accordingly, the thin film type LED package of the present invention may exhibit high reliability without being easily damaged by mechanical thermal shock.

Furthermore, by using a plate-shaped bent lead frame instead of having a separate substrate or a reflecting frame, it is easy to thin the package thickness and is advantageous for implementing a thin film package.

Claims (15)

A plate-shaped lead frame in which a center portion is bent to have a reflecting cup, An LED chip mounted on a bottom of the reflective cup, And a molding part encapsulating the LED chip and the lead frame to expose a bottom surface of the bottom of the reflecting cup to dissipate heat generated from the LED chip. The lead frame is bent to the lower portion of the molding portion outside the upper end of the reflecting cup and extends laterally at both ends so that both ends of the lead frame are exposed to the outside from the molding to form a connection terminal with an external circuit. Thin film light emitting diode package. delete The method of claim 1, The molding part, An inner molding part formed inside the reflecting cup to encapsulate the LED chip; The thin film type light emitting diode package is formed on the outside of the inner molding portion and comprises an outer molding portion encapsulating the lead frame. The method of claim 3, The inner molding part is a thin film type light emitting diode package, characterized in that the phosphor for changing the light emitted from the LED chip is dispersed. The method of claim 1, The lead frame includes a first lead portion having a reflective cup and a second lead portion separated from the first lead portion. The method of claim 1, The thin film type light emitting diode package further comprises a Zener diode connected in parallel with the LED chip. The method of claim 6, The zener diode is a thin-film type light emitting diode package, characterized in that mounted on the upper outer surface of the reflecting cup. Preparing a metal plate for the leadframe; Bending the central portion of the metal plate to form a flat ridge; Bending the inside of the ridge to form a reflective cup to obtain a lead frame; Mounting an LED chip on the bottom of the reflecting cup; Exposing the bottom surface of the reflecting cup to dissipate heat generated from the LED chip and encapsulating the LED chip and the lead frame with a molding resin so that both ends of the lead frame are exposed to form an external circuit and a connection terminal. Method of manufacturing a thin film light emitting diode package comprising a. delete The method of claim 8, The encapsulation step, A first encapsulation step of applying a molding resin to the reflection cup to encapsulate the LED chip; And a second encapsulation step of forming a molding resin to encapsulate the lead frame. The method of claim 10, In the first encapsulation step, a method of manufacturing a thin film type light emitting diode package, characterized in that for applying a molding resin in which the phosphor is dispersed. The method of claim 8, The lead frame is a manufacturing method of a thin film type light emitting diode package, characterized in that formed with a first lead portion formed with a reflective cup and a second lead portion separated from the first lead portion. The method of claim 8, Before the encapsulation step, mounting the zener diode to be connected in parallel with the LED chip. The method of claim 13, The zener diode is a manufacturing method of the thin-film type light emitting diode package, characterized in that mounted on the upper outer surface of the reflecting cup. The method of claim 8, And a trimming step of cutting out unnecessary metal plate portions protruding from the molding resin.

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