This application claims the priority of Korean Patent Application No. 10-2010-0123508 filed on Dec. 6, 2010, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to a light emitting device package and a method of manufacturing the same.
2. Description of the Related Art
In general, alight emitting device package containing a light emitting diode (LED) in which a light emission operation is performed in response to an electrical signal is widely used in various kinds of electronic products including a mobile communications terminal such as a personal mobile phone, a personal digital assistant (PDA), or the like.
A package structure, according to a related art, having an LED installed therein, generally has a cup-shaped cavity formed in a package body thereof formed of a high reflectivity material to reduce light loss in light emitted from a light emitting device and has the cavity filled with a silicon-based or epoxy-based gel-type polymer having relatively prominent light transmittance characteristics and heat resistance after installing the light emitting device in the cavity.
In this case, since a light emission surface and a bonding position of a wire exist on the same level, light may not be emitted from the light emission surface in sufficient quantities due to intervening elements such as the bonding pads or the like, bonded to the light emission surface, thus decreasing light extraction efficiency. In addition, since a separate heat sink should be provided on a lower part of the light emitting device, the manufacturing of a mold may be complicated and manufacturing costs may increase.
An aspect of the present invention provides a light emitting device package and a method of manufacturing the same, which is capable of having significantly increased light extraction efficiency by changing a position in which a wire bonding pad is located so as to substantially enlarge a light emission surface.
Another aspect of the present invention provides a light emitting device package and a method of manufacturing the same, having a simplified overall manufacturing process due to a post-molding process, thereby improving productivity and product reliability.
According to an aspect of the present invention, there is provided a light emitting device package including: a plurality of lead frames disposed to be separated from one another; at least one light emitting device provided with a wire bonding pad attached to a lower surface thereof opposite to an upper light emission surface thereof, and mounted on the lead frames such that the wire bonding pad is positioned in a space between the lead frames; a bonding wire electrically connecting the wire bonding pad to the lead frame through the space between the lead frames; and a mold part encapsulating the lead frames, the light emitting device and the bonding wire, and having a reflection groove formed in an upper surface thereof to expose the light emission surface to the outside therethrough and a pad groove formed in a bottom surface thereof to expose a portion of the lead frame so as to form a solder pad thereon.
The light emitting device package may further include an envelope part formed within the reflection groove to cover the light emission surface.
The envelope part may contain any one of a fluorescent material, a diffusion material and a mixture thereof.
The light emitting device package may further include a lens part provided on the mold part.
The lead frame may include an open part formed to penetrate through a portion thereof corresponding to a position of the wire bonding pad, through which the wire bonding pad of the light emitting device is downwardly exposed.
The mold part may be formed such that a bottom surface of the reflection groove is on the same level as the light emission surface of the light emitting device.
The mold part may be formed such that the bottom surface of the reflection groove is on the same level as an upper surface of the lead frame on which the light emitting device is mounted.
The bottom surface of the reflection groove may be circular, quadratic or polygonal.
According to another aspect of the present invention, there is provided a method of manufacturing a light emitting device package, including: preparing a light emitting device provided with a wire bonding pad attached to a lower portion surface opposite to an upper light emission surface thereof; mounting at least one light emitting device on a plurality of lead frames disposed to be separated from one another allowing for the wire bonding pad to be positioned in a space between the lead frames; electrically connecting the light emitting device to the lead frame by bonding one end of the bonding wire to the wire bonding pad and bonding the other end thereof to the lead frame, the other end thereof extending toward a lower surface of the lead frame through the space between the lead frames; forming a mold part through a molding process to encapsulate the light emitting device mounted on the lead frames together with the bonding wires by applying a resin thereto, the mold part being provided with a reflection groove formed in an upper surface thereof to expose the light emitting device therethrough and provided with a pad groove formed in a bottom surface thereof to expose a portion of the lead frame therethrough so as to form a solder pad thereon; and forming an envelope part within the reflection groove to cover the light emitting device.
The preparing of the light emitting device may further include forming a fluorescent substance layer on the light emission surface.
The mounting of the light emitting device may include forming an open part to penetrate through the lead frame, and mounting the light emitting device on the lead frames such that the wire bonding pad of the light emitting device is exposed toward a lower surface of the lead frame through the open part.
The electrical connecting of the light emitting device and the lead frame may include bonding one end of the bonding wire to the wire bonding pad and bonding the other end thereof to the lead frame, the other end thereof extending toward a lower surface of the lead frame through the open part.
In addition, the forming of the mold part may include performing a molding process such that a light emitting device is disposed within the reflection groove or a plurality thereof are disposed therein.
The forming of the mold part may include performing the molding process such that the bottom surface of the reflection groove is equal to that of a height of the light emission surface of the light emitting device and thus the light emission surface is exposed through the reflection groove.
In addition, the forming of the mold part may include performing the molding process such that the bottom surface of the reflection groove is on the same level as an upper surface of the lead frame on which the light emitting device is mounted so as to expose the light emission surface, a side surface of the light emitting device and an upper portion of the lead frame through the reflection groove.
The method may further include adapting a lens part on the mold part.
The method may further include arranging a frame sheet on which the plurality of lead frames are formed before the mounting of the light emitting device is performed.
The method may further include forming a solder pad in the pad groove after the forming of the mold part is performed.
The method may further include dicing along a cutting line.
The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
Exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings such that they could be easily practiced by those having skill in the art to which the present invention pertains. However, in describing the exemplary embodiments of the present invention, detailed descriptions of well-known functions or constructions will be omitted so as not to obscure the description of the present invention with unnecessary detail.
In addition, like reference numerals denote like elements throughout the drawings.
Unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising,” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.
According to an embodiment of the present invention, a light emitting device package will be described with reference to
Referring to
The plurality of lead frames 10 are separated from one another by a predetermined interval so as not to be electrically connected to one another.
The light emitting device 20 is a semiconductor device able to emit light having a given wavelength in response to an electrical signal applied from the outside, and may include light emitting chips or a light emitting device package having light emitting chips mounted therein. The light emitting device 20 may emit blue light, red light or green light according to the material contained therein, and may also emit white light.
The light emitting device 20 may emit light to the outside through a light emission surface 21 provided as an upper surface thereof, and a lower surface opposite to the upper surface may be provided with a wire bonding pad 23 receiving the electrical signal. The light emitting device 20 may be mounted on the lead frame 10 such that the wire bonding pad 23 is positioned in a space 11 between the lead frames 10. Therefore, when the light emitting device 20 is mounted on the lead frames 10, the wire bonding pad 23 provided with a lower surface of the light emitting device 20 is exposed toward the lower surface of the lead frame 10 through the space 11 between the lead frames.
The light emitting device 20 may be bondedly fixed to the lead frames 10 through a bonding member 70 provided between the lead frame and the light emitting device. The bonding member 70 may be formed as a tape type adhesion layer on the lead frame 10, or formed as a paste type layer thereon using a spraying method, a printing method, a dispensing method, or the like. In this case, the tape or paste may have a high density of high heat transfer filler. Further, the light emitting device 20 may be directly adhered to the lead frames 10 through metal bonding, and in this case, a heat transfer characteristic between the light emitting device 20 and the lead frames 10 may be relatively more effective. A single light emitting device 20 may be mounted on the lead frames 10 as shown in
The bonding wire 30 may electrically connect the light emitting device 20 with the lead frames through the space as an interval between the lead frames. Described in detail, one end of the bonding wire 30 is bonded to the wire bonding pad 23 of the light emitting device 20, and the other end thereof is bonded to the lead frame 10 by being extending toward a lower surface of the lead frame 10.
The mold part 40 may encapsulate the light emitting device 20 mounted between the lead frame 10 and the lead frame 10, and the bonding wire 30 electrically connecting the lead frame 10 to the light emitting device 20, while supporting the light emitting device and the bonding wire therein. A reflection groove 41 may be formed on an upper surface of the mold part 40 to which the light emission surface 21 of the light emitting device 20 is exposed, and a pad groove 42 to which the lead frame 10 is partially exposed may be formed on a bottom surface of the mold part 40. In the pad groove 42, a solder pad 80 is formed to be electrically connected to a circuit wiring (not shown) of a substrate not shown in the drawings on which the light emitting device package 1 is mounted.
As shown in
As shown in
The pad groove 42, formed in a lower surface of the mold part 40 may be circular or quadrangular, as shown in
An envelope part 50 may be formed within the reflection groove 41 to cover and protect the light emission surface 21. The envelope part 50 may be formed of a transparent resin such that light emitted from the light emitting device 20 can be efficiently discharged to the outside. The envelope part 50 may contain fluorescent material, by which a wavelength of light generated from the light emitting device 20 may be converted into a required wavelength. For example, blue light may be converted in white light. The envelope part 50 may contain a diffusion material to diffuse light, in addition to the fluorescent material, or contain a mixture thereof.
As shown in
The lens part 60 may be formed on the mold part 40 as shown in
A light emitting device package according to another embodiment of the present invention will be described with reference to
The light emitting device package according to the embodiment of the present invention with reference to
As shown in
A method of manufacturing a light emitting device package will now be described according to an embodiment of the present invention with reference to
First, the light emitting device 20, which is provided with the bonding pads 23 that are positioned on a lower surface thereof opposite to the light emitting surface 21 as the upper surface of the light emitting device 20, may be prepared as shown in
The light emitting device 20 may be prepared by singulating a light emitting laminate of an n-type semiconductor layer, an active layer and a p-type semiconductor layer grown sequentially through a chemical vapor deposition apparatus (not shown) by separate dies on a wafer level. In this case, the fluorescent substance layer 25 may be further formed on the light emission surface 21 of the light emitting device 20. The fluorescent substance layer 25 may be formed to be entirely covered on the light emitting laminate or adhere thereto on the wafer level before being singulated into the separate dies.
Meanwhile, the method may further include arranging a frame sheet F on which the plurality of lead frames 10 are formed before mounting the light emitting devices 20. Described in more in detail, the plurality of lead frames 10 may be formed to be separated from one another by a predetermined interval by performing repeated patterning on a metal plate formed of material having a relatively large electrical conductivity and heat conductivity properties as shown in
Meanwhile, the mounting of the light emitting device 20 may include forming the open part 12 penetrating through the lead frame 10, and mounting the light emitting device 20 on the lead frames 10 such that the wire bonding pads 22 of the light emitting device 20 are exposed toward lower surfaces of the lead frames 10 through the open parts 12. Described in detail, as shown in
Subsequently, as shown in
Then, the mold part 40 may be formed by applying resin thereto to encapsulate the light emitting device 20 mounted on the lead frames 10 together with the bonding wires 30 as shown in
In the mold part 40, the molding process may be performed such that the bottom surface of the bottom part 411 of the reflection groove 41 is on the same level as the light emission surface 21 of the light emitting device 20 and thus, only the light emission surface 21 may be exposed through the reflection groove 41 as shown in
As described above, in a post molding method of forming the mold part 40 after the light emitting device 20 is mounted on the lead frames 10 and the wire bonding process is completed, an overall process may be simplified since a non-value added process such as a bake and the like before introducing resin material is omitted, unlike a pre-molding method of mounting a light emitting device in a state in which the existing mold part has been formed and of performing a wire bonding process. In addition, the molding process may be performed by controlling the structure of the reflection groove 41 to control a degree of exposure of the light emitting device 20, that is, only an upper surface thereof or the upper surface and the side surface thereof may be exposed, thereby preventing an unnecessary waste of space and significantly facilitating miniaturization and light collection efficiency.
Then, as shown in
Subsequently, as shown in
The solder pad 80 may be formed in the pad groove 42 that is provided in a lower surface of the mold part 40. The solder pad 80 may be formed after forming the mold part 40, or forming the envelope part 50 or forming the lens part 60 as shown in
Then, a plurality of light emitting device packages may be manufactured by dicing along a cutting line C shown in
As set forth above, according to an embodiment of the present invention, emitted light is not interfered with by a wire bonding pad or a bonding wire, thereby significantly increasing light extraction efficiency.
In addition, according to an embodiment of the present invention, a degree of freedom enjoyed in the design and number of wire bonding pads is improved, thereby improving electrical characteristics.
Further, according to an embodiment of the present invention, since the molding process is performed after chip bonding and wire bonding processes, a non-value added process such as bake processing and the like before introducing molding material may be omitted, thereby simplifying an overall process.
In addition, according to an embodiment of the present invention, wire bonding is performed within a chip area so as to reduce the overall size of a package.
Furthermore, since in a general epi-up (eg, p-side up) chip, light is also emitted from a side surface of a growth substrate, a fluorescent layer should be applied to cover not only an upper part of chip but a side surface thereof; however, according to an embodiment of the present invention, a fluorescent layer may be formed only on an upper part of chip by using a light reflection mold material encapsulating the periphery of the chip, thereby relatively easily forming a fluorescent layer and reducing a distribution of light quality.
In addition, according to an embodiment of the present invention, a wire is encapsulated using a molding material prominent in a mechanical physical characteristic, thereby enhancing reliability in a wire junction.
While the present invention has been shown and described in connection with the exemplary embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.
Number | Date | Country | Kind |
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10-2010-0123508 | Dec 2010 | KR | national |