Light emitting device package, backlight unit, and method of manufacturing light emitting device package

Disclosed herein are a light emitting device package, a backlight unit, and a method of manufacturing a light emitting device package capable of being used for a display application or an illumination application. The light emitting device package includes: a flip-chip type light emitting device having a first pad and a second pad; a lead frame having a first electrode installed at one side of an electrode separation space and a second electrode installed at the other side thereof, and having the light emitting device seated thereon; a first bonding medium installed between the first pad and the first electrode so that the first pad of the light emitting device and the first electrode of the lead frame are electrically connected to each other; and a second bonding medium installed between the second pad and the second electrode so that the second pad of the light emitting device and the second electrode of the lead frame are electrically connected to each other, wherein at least one first accommodating cup part accommodating the first bonding medium therein is formed in the first electrode of the lead frame, and at least one second accommodating cup part accommodating the second bonding medium therein is formed in the second electrode of the lead frame.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a National Stage entry of the International Application No. PCT/KR2015/001010, filed on Jan. 30, 2015, claiming priority to Korean Patent Application No. 10-2014-0012277, filed on Feb. 3, 2014, the content of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a light emitting device package, a backlight unit, and a method of manufacturing a light emitting device package, and more particularly, a light emitting device package, a backlight unit, and a method of manufacturing a light emitting device package capable of being used for a display application or an illumination application.

BACKGROUND ART

A light emitting diode (LED) indicates a kind of semiconductor device capable of implementing various colors of light by forming a PN diode using a compound semiconductor to configure a light emitting source. The LED has a long lifespan, may be miniaturized and become light, and may be driven at a low voltage. In addition, the LED is robust to impact and vibration, does not require a preheating time and complicated driving, and may be mounted in various shapes on a substrate or a lead frame and be then packaged, such that the LED may be modularized for several applications and be used in a backlight unit, various illumination apparatuses, or the like.

DISCLOSURE

Technical Problem

However, in a light emitting device package according to the related art, in the case in which a solder paste is applied onto a substrate, when an excessively small amount of solder paste is applied onto the substrate, adhesion strength between the substrate and a light emitting device is reduced, such that a short-circuit phenomenon may occur, when an excessively large amount of solder paste is applied onto the substrate, the solder paste is pressed by the light emitting device at the time of seating the light emitting device, such that the solder paste gets over an electrode separation line along the substrate to be spread, thereby generating a short-circuit.

In addition, in the light emitting device package according to the related art, since the light emitting device contacts the solder paste in a flow state to be cured, a light emitting axis of the light emitting device is inclined or misaligned, such that optical performance is deteriorated.

The present invention is to solve several problems including the problems as described above, and an object of the present invention is to provide a light emitting device package, a backlight unit, and a method of manufacturing a light emitting device package in which an adhesion property may be improved and a short-circuit may be prevented by forming accommodating cup parts capable of accommodating a solder paste therein in a substrate, and a light emitting axis may be accurately aligned by allowing a light emitting device to directly contact the substrate at the time of seating the light emitting device. However, this object is only an example, and the scope of the present invention is not limited thereto.

Technical Solution

According to an exemplary embodiment of the present invention, a light emitting device package includes: a flip-chip type light emitting device having a first pad and a second pad; a lead frame having a first electrode installed at one side of an electrode separation space and a second electrode installed at the other side thereof, and having the light emitting device seated thereon; a first bonding medium installed between the first pad and the first electrode so that the first pad of the light emitting device and the first electrode of the lead frame are electrically connected to each other; and a second bonding medium installed between the second pad and the second electrode so that the second pad of the light emitting device and the second electrode of the lead frame are electrically connected to each other, wherein at least one first accommodating cup part accommodating the first bonding medium therein is formed in the first electrode of the lead frame, and at least one second accommodating cup part accommodating the second bonding medium therein is formed in the second electrode of the lead frame.

A width or a length of an inlet of the first accommodating cup part may be smaller than a width or a length of the first pad and a width or a length of an inlet of the second accommodating cup part may be smaller than a width or a length of the second pad so that one portion of the first pad of the light emitting device directly contacts the first electrode of the lead frame and one portion of the second pad of the light emitting device directly contacts the second electrode of the lead frame.

The first accommodating cup part and the second accommodating cup part may be positioned within footprint regions of the first pad and the second pad. The first bonding medium and the second bonding medium may be solder pastes applied or dispensed onto the first accommodating cup part and the second accommodating cup part, respectively.

A plurality of first accommodating cup parts may be disposed in parallel with each other in a length direction or a width direction of the first pad. The first accommodating cup part and the second accommodating cup part may be formed of any one selected from the group consisting of at least quadrangular groove parts having a quadrangular cross section, polygonal groove parts having a polygonal cross section, and round groove parts having a round cross section, and the first accommodating cup part and the second accommodating cup part may have bottom slopes or side slopes so as to guide the first bonding medium and the second bonding medium in a direction that becomes distant from the electrode separation space. The light emitting device package may further include a reflection encapsulant filled in the electrode separation space to form an electrode separation wall and form a reflection cup part enclosing side circumferences of the light emitting device.

According to another exemplary embodiment of the present invention, a backlight unit includes: a flip-chip type light emitting device having a first pad and a second pad; a lead frame having a first electrode installed at one side of an electrode separation space and a second electrode installed at the other side thereof, and having the light emitting device seated thereon; a first bonding medium installed between the first pad and the first electrode so that the first pad of the light emitting device and the first electrode of the lead frame are electrically connected to each other; a second bonding medium installed between the second pad and the second electrode so that the second pad of the light emitting device and the second electrode of the lead frame are electrically connected to each other; and a light guide plate installed in a light path of the light emitting device, wherein at least one first accommodating cup part accommodating the first bonding medium therein is formed in the first electrode of the lead frame, and at least one second accommodating cup part accommodating the second bonding medium therein is formed in the second electrode of the lead frame.

According to still another exemplary embodiment of the present invention, a method of manufacturing a light emitting device package includes: preparing a lead frame having a first electrode installed at one side of an electrode separation space, a second electrode installed at the other side thereof, a first accommodating cup part formed in the first electrode, and a second accommodating cup part formed in the second electrode; applying or dispensing a first bonding medium onto the first accommodating cup part and applying or dispensing a second bonding medium onto the second accommodating cup part; seating a light emitting device on the lead frame so that one portion of the first pad directly contacts the first electrode and the other portion of the first pad is electrically connected to the first bonding medium and one portion of the second pad directly contacts the second electrode and the other portion of the second pad is electrically connected to the second bonding medium; and allowing the first bonding medium and the second bonding medium to reflow.

Advantageous Effects

According to some exemplary embodiments of the present invention configured as described above, the accommodating cup parts capable of accommodating the solder paste therein are formed in the substrate to increase an adhesion surface area, thereby making it possible to improve an adhesion property and to guide the solder paste in a direction that becomes distant from an electrode separation line, thereby making it possible to prevent a short-circuit phenomenon. In addition, the first and second pads of the light emitting device may directly contact the substrate at the time of seating the light emitting device, thereby making it possible to accurately arrange a light emitting axis, and the light emitting device is firmly fused to the bonding media in the accommodating cup parts, such that a fusion path is improved, thereby making it possible to prevent a chip lift defect. The scope of the present invention is not limited to the above-mentioned effects.

BEST MODE

Hereinafter, several exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Exemplary embodiments of the present invention will be provided only in order to further completely describe the present invention to those skilled in the art, the following exemplary embodiments may be modified into several other forms, and the scope of the present invention is not limited to the following exemplary embodiments. Rather, these exemplary embodiments make the present disclosure thorough and complete, and are provided in order to completely transfer the spirit of the present invention to those skilled in the art. In addition, thicknesses or sizes of the respective layers in the drawings have been exaggerated for convenience and clarity of explanation.

FIG. 1is an exploded perspective view illustrating a light emitting device package100according to some exemplary embodiments of the present invention. In addition,FIG. 2is a cross-sectional view of the light emitting device package100taken along line II-II ofFIG. 1, andFIG. 3is a plan view of the light emitting device package100ofFIG. 1.

First, as illustrated inFIGS. 1 to 3, the light emitting device package100according to some exemplary embodiments of the present invention may mainly include a light emitting device10, a lead frame20, a first bonding medium B1, and a second bonding medium B2. Here, the light emitting device10may be a flip-chip type light emitting diode (LED) having a first pad P1and a second pad P2.

The light emitting device10may be formed of a semiconductor, as illustrated inFIG. 1. For example, LEDs formed of a nitride semiconductor and emitting blue light, green light, red light, and yellow light, an LED formed of a nitride semiconductor and emitting ultraviolet light, an LED formed of a nitride semiconductor and emitting infrared light, or the like, may be used. In addition, as the light emitting device10, a light emitting device having any wavelength may be selected according to an application such as a display application, an illumination application, or the like.

Here, as the substrate for growth, an insulating substrate, a conductive substrate, or a semiconductor substrate may be used as needed. In addition, as a heterogeneous substrate, a sapphire substrate, a silicon carbide (SiC) substrate, or the like, has been mainly used, and the sapphire substrate has been mainly used as compared with the silicon carbide substrate which is expensive.

In addition, another support substrate may be used at the time of removing the substrate for growth. In this case, the support substrate may be bonded to an opposite side to an original growth substrate using a reflecting metal or a reflection structure may be inserted in the middle of a bonding layer, in order to improve light efficiency of an LED chip. Further, patterning of the substrate for growth forms a rugged part or a slope before or after growth of the LED structure on main surfaces (surfaces or both surfaces) or side surfaces of the substrate, thereby improving light extraction efficiency.

Further, although not illustrated, the light emitting device10may be a flip-chip type light emitting device having a signal transfer medium such as a bump, a solder, or the like, in addition to the pads P1and P2. Further, all of light emitting devices in which bonding wires are applied to terminals or are applied to only a first terminal or a second terminal, such as a horizontal type light emitting device, a vertical type light emitting device, and the like, may be applied.

The first pad P1and the second pad P2may have various shapes in addition to a quadrangular shape illustrated inFIG. 1. For example, the first pad P1and the second pad P2may have a finger structure in which a plurality of fingers are provided on one arm. In addition, one light emitting device10may be installed on the lead frame20, as illustrated inFIG. 1, or a plurality of light emitting devices10may be installed on the lead frame20.

Meanwhile, the lead frame20may be a kind of substrate having a first electrode21installed at one side of an electrode separation space and a second electrode22installed at the other side thereof. The lead frame20may be formed of a material having appropriate mechanical strength and an insulating property so as to support the light emitting device10or accommodate the light emitting device10therein or a conductive material.

In addition, instead of the lead frame20, a synthetic resin substrate formed of a resin, glass epoxy, or the like, may be used or a ceramic substrate may be used in consideration of thermal conductivity. Further, the lead frame20may be partially or entirely formed of one or more selected from the group consisting of at least an epoxy molding compound (EMC), polyimide (PI), ceramic, graphene, glass synthetic fiber, and combinations thereof in order to improve workability.

Meanwhile, the first bonding medium B1may be a bonding member installed between the first pad P1and the first electrode21so that the first pad P1of the light emitting device10and the first electrode21of the lead frame20may be electrically connected to each other. In addition, the second bonding medium B2may be a bonding member installed between the second pad P2and the second electrode22so that the second pad P2of the light emitting device10and the second electrode22of the lead frame20may be electrically connected to each other.

Here, the first bonding medium B1and the second bonding medium B2may be solder pastes or solder creams applied or dispensed onto a first accommodating cup part21aand a second accommodating cup part22a, respectively. In addition, the first bonding medium B1and the second bonding medium B2may be conductive bonding media, which are all curable materials that are in a flow state in which they may flow at the time of being bonded but are cured at the time of being cooled, heated, or dried, such as a solder, or the like.

Meanwhile, in the light emitting device package100according to some exemplary embodiments of the present invention, at least one first accommodating cup part21acapable of accommodating the first bonding medium B1therein may be formed in the first electrode21of the lead frame20, and at least one second accommodating cup part22acapable of accommodating the second bonding medium B2therein may be formed in the second electrode22of the lead frame20.

Here, as illustrated inFIG. 2, a width W2or a length of an inlet of the first accommodating cup part21amay be smaller than a width W1or a length of the first pad P1and a width W2or a length of an inlet of the second accommodating cup part22amay be smaller than a width W1or a length of the second pad P2so that one portion of the first pad P1of the light emitting device10may directly contact the first electrode21of the lead frame20and one portion of the second pad P2of the light emitting device10may directly contact the second electrode22of the lead frame20.

Therefore, since one portion of the first pad P1of the light emitting device10may directly contact the first electrode21of the lead frame20and one portion of the second pad P2of the light emitting device10may directly contact the second electrode22of the lead frame20, the first and second pads P1and P2of the light emitting device10may directly contact the lead frame20at the time of seating the light emitting device, such that the light emitting device10is not inclined or misaligned, thereby making it possible to accurately arrange a light emitting axis.

In addition, as illustrated inFIG. 3, the first accommodating cup part21aand the second accommodating cup part22amay be positioned within footprint regions A1and A2of the first pad P1and the second pad P2. Therefore, an edge portion of the first pad P1of the light emitting device10directly contacts the first electrode21of the lead frame20, such that a gap is not present, and an edge portion of the second pad P2of the light emitting device10directly contacts the second electrode22of the lead frame20, such that a gap is not present. Accordingly, the first accommodating cup part21aand the second accommodating cup part22aare sealed, such that the first bonding medium B1and the second bonding medium B2are not leaked to the outside of the first accommodating cup part21aand the second accommodating cup part22a.

At the same time, it is possible to prevent other phosphors, a transparent encapsulant, a reflecting member, or other molding materials from permeating into the first accommodating cup part21aand the second accommodating cup part22a. It is obvious that the first accommodating cup part21aand the second accommodating cup part22aare positioned in a footprint region A3of the light emitting device10.

Here, for example, a footprint region of the first pad P1, indicates a region of the lead frame20on which the first pad P1is projected on a plan view, may mean a bottom area occupied by the first pad P1on the lead frame20.

FIG. 4is a plan view illustrating a light emitting device package200according to some other exemplary embodiments of the present invention. As illustrated inFIG. 4, in the light emitting device package200according to some other exemplary embodiments of the present invention, a plurality of first accommodating cup parts21aand a plurality of second accommodating cup parts22amay be disposed in parallel with each other in a length direction and a width direction of the first pad P1, respectively.

As illustrated inFIG. 4, seven first accommodating cup parts21aand seven second accommodating cup parts22aare disposed in the length direction, respectively, and two first accommodating cup parts21aand two second accommodating cup parts22aare disposed in the width direction, respectively, such that a total number of each of the first accommodating cup parts21aand the second accommodating cup parts22amay be fourteen. Here, the numbers, positions, or the like, of the first accommodating cup parts21aand the second accommodating cup parts22amay be variously applied, for example, two, four, eight, or the like, and are not limited to the present drawing.

FIGS. 5 to 9are cross-sectional views illustrating accommodating cup parts21aand22aof a light emitting device package according to various exemplary embodiments. As illustrated inFIGS. 5 to 9, the first accommodating cup part21aand the second accommodating cup part22aare not limited to quadrangular groove parts H1having a quadrangular cross section as illustrated inFIGS. 2 to 5, but may be inverse rhomboid groove parts H3having an inverse rhomboid cross section as illustrated inFIG. 7or round groove parts H2having a round cross section as illustrated inFIG. 6. In addition, although not illustrated, the first accommodating cup part21aand the second accommodating cup part22amay be polygonal groove parts having a polygonal cross section or groove parts having various geometric cross sections.

In addition, as illustrated inFIG. 8, the first accommodating cup part21aand the second accommodating cup part22amay have bottom slopes C1so as to guide the first bonding medium B1and the second bonding medium B2in a direction that becomes distant from the electrode separation space. Here, the bottom slopes C1may have a shape in which portions thereof close to the electrode separation space are high and portions thereof distant from the electrode separation space are low so as to guide the first bonding medium B1and the second bonding medium B2in the direction that becomes distant from the electrode separation space.

Here, the bottom slopes C1are not necessarily limited to bottom surfaces. That is, as illustrated inFIG. 9, the first accommodating cup part21aand the second accommodating cup part22amay have side slopes C2so as to guide the first bonding medium B1and the second bonding medium B2in the direction that becomes distant from the electrode separation space. Here, the side slopes C2may have a shape in which portions thereof close to the electrode separation space are high and portions thereof distant from the electrode separation space are low so as to guide the first bonding medium B1and the second bonding medium B2in the direction that becomes distant from the electrode separation space. In addition, these slopes may be formed in various forms within the first accommodating cup part21aand the second accommodating cup part22a.

Meanwhile, as illustrated inFIGS. 1 to 4, the light emitting device packages100and200according to the present invention may further include a reflection encapsulant30filled in the electrode separation space to form an electrode separation wall31and form a reflection cup part32enclosing side circumferences of the light emitting device, and a filler40filled in the reflection cup part32. Here, the electrode separation wall31and the reflection cup part32of the reflection encapsulant30may be molded and formed integrally with each other by a mold.

Here, the filler may be formed of one or more selected from the group consisting of at least silicon, transparent epoxy, a phosphor, and a combination thereof, which are materials having a relatively small particle size and being dense. In addition, the phosphor may include materials such as a quantum dot, and the like. As the phosphor, the above-mentioned oxide based material, nitride based material, silicate based material, and QD material may be singly used or a mixture thereof may be used.

In order to generate a difference in optical efficiency and light distribution characteristics, a light converting material may be positioned in a remote form. In this case, the light converting material is positioned together with translucent polymer, glass, or the like, depending on durability and heat resistance. Since a technology of applying the phosphor plays the largest role in determining optical characteristics in the light emitting device, various studies on control technologies of a thickness of a phosphor applied layer, uniform dispersion of the phosphor, and the like, have been conducted. The quantum dot may also be positioned in the LED chip or the light emitting device, similar to the phosphor, and be positioned between glass or translucent polymer materials to perform light conversion.

FIG. 15is a cross-sectional view illustrating a backlight unit1000according to some exemplary embodiments of the present invention.

As illustrated inFIG. 15, the backlight unit1000according to some exemplary embodiments of the present invention may include a flip-chip type light emitting device10having a first pad P1and a second pad P, a lead frame20having a first electrode21installed at one side of an electrode separation space and a second electrode22installed at the other side thereof, a first bonding medium B1installed between the first pad P1and the first electrode21so that the first pad P1of the light emitting device10and the first electrode21of the lead frame20may be electrically connected to each other, a second bonding medium B2installed between the second pad P2and the second electrode22so that the second pad P2of the light emitting device10and the second electrode22of the lead frame20may be electrically connected to each other, and a light guide plate50installed in a light path of the light emitting device10, wherein at least one first accommodating cup part21acapable of accommodating the first bonding medium B1therein may be formed in the first electrode21of the lead frame20, and at least one second accommodating cup part22acapable of accommodating the second bonding medium B2therein may be formed in the second electrode22of the lead frame20.

Here, roles and configurations of the light emitting device10, the lead frame20, the first bonding medium B1, the second bonding medium B2, the first accommodating cup part21a, and the second accommodating cup part22amay be the same as those of the corresponding components of the light emitting device package100according to some exemplary embodiments of the present invention described above as illustrated inFIG. 1. Therefore, a detailed description for these components will be omitted.

In addition, the light guide plate50may be an optical member that may be formed of a translucent material so as to guide the light generated in the light emitting device10. The light guide plate50may be installed in a path of the light generated in the light emitting device10, and transfer the light generated in the light emitting device10to a wider area.

Here, although not illustrated, various diffusion sheets, a prism sheet, a filter, and the like, may be additionally installed above the light guide plate50. In addition, various display panels such as a liquid crystal display (LCD) panel, and the like, may be installed above the light guide plate50. Meanwhile, although not illustrated, the present invention may include an illumination apparatus including the light emitting device package100described above. Here, configurations and roles of components of the illumination apparatus according to some exemplary embodiments of the present invention may be the same as those of the corresponding components of the light emitting device package according to the present invention described above. Therefore, a detailed description for these components will be omitted.

FIGS. 10 to 14are cross-sectional views illustrating steps of a process of manufacturing a light emitting device package100according to some exemplary embodiments of the present invention. The steps of the process of manufacturing a light emitting device package100according to some exemplary embodiments of the present invention will be described with reference toFIGS. 10 to 14. First, as illustrated inFIG. 10, the lead frame20having the first electrode21installed at one side of the electrode separation space, the second electrode22installed at the other side thereof, the first accommodating cup part21aformed in the first electrode21, and the second accommodating cup part22aformed in the second electrode22may be prepared.

Then, as illustrated inFIG. 11, the electrode separation wall31and the reflection cup part32of the reflection encapsulant30may be molded integrally with each other using a mold. Then, as illustrated inFIG. 12, the first bonding medium B1and the second bonding medium B2such as a solder paste, or the like, may be applied or dispensed onto the first accommodating cup part21aand the second accommodating cup part22aby various printing methods such as an inkjet printing method, a stencil printing method, a squeeze printing method, and the like, as well as an ultra-precision transfer method or an ultra-precision stamping method.

Then, as illustrated inFIG. 13, the light emitting device10may be seated on the lead frame20so that one portion of the first pad P1may directly contact the first electrode21and the other portion of the first pad P1may be electrically connected to the first bonding medium B1and one portion of the second pad P2may directly contact the second electrode22and the other portion of the second pad P2may be electrically connected to the second bonding medium B2.

Here, since one portion of the first pad P1of the light emitting device10may directly contact the first electrode21of the lead frame20and one portion of the second pad P2of the light emitting device10may directly contact the second electrode22of the lead frame20, the first and second pads P1and P2of the light emitting device10may directly contact the lead frame20at the time of seating the light emitting device, such that the light emitting device10is not inclined or misaligned, thereby making it possible to accurately arrange a light emitting axis, an edge portion of the first pad P1of the light emitting device10directly contacts the first electrode21of the lead frame20, such that a gap is not present, and an edge portion of the second pad P2of the light emitting device10directly contacts the second electrode22of the lead frame20, such that a gap is not present. Accordingly, the first accommodating cup part21aand the second accommodating cup part22aare sealed, such that the first bonding medium B1and the second bonding medium B2are not leaked to the outside of the first accommodating cup part21aand the second accommodating cup part22a.

In addition, the light emitting device10is firmly fused to the first bonding medium B1and the second bonding medium B2in the first accommodating cup part21aand the second accommodating cup part22a, such that a fusion path is improved, thereby making it possible to prevent a chip lift defect. The, as illustrated inFIG. 13, the first bonding medium B1and the second bonding medium B2may be heated to reflow, in order to being cured.

FIG. 16is a flow chart illustrating a method of manufacturing a light emitting device package100according to some exemplary embodiments of the present invention. As illustrated inFIGS. 10 to 16, the method of manufacturing a light emitting device package100according to some exemplary embodiments of the present invention may include preparing a lead frame20having a first electrode21installed at one side of an electrode separation space, a second electrode22installed at the other side thereof, a first accommodating cup part21aformed in the first electrode21, and a second accommodating cup part22aformed in the second electrode22(S1), applying or dispensing a first bonding medium B1onto the first accommodating cup part21aand applying or dispensing a second bonding medium B2onto the second accommodating cup part22a(S2), seating a light emitting device10on the lead frame20so that one portion of the first pad P1may directly contact the first electrode21and the other portion of the first pad P1may be electrically connected to the first bonding medium B1and one portion of the second pad P2may directly contact the second electrode22and the other portion of the second pad P2may be electrically connected to the second bonding medium B2(S3), and allowing the first bonding medium B1and the second bonding medium B2to reflow (S4).

Although the present invention has been described with reference to exemplary embodiments illustrated in the accompanying drawings, it is only an example. It will be understood by those skilled in the art that various modifications and equivalent other exemplary embodiments are possible from the present invention. Accordingly, the actual technical protection scope of the present invention is to be defined by the following claims.

INDUSTRIAL APPLICABILITY

According to some exemplary embodiments of the present invention configured as described above, the accommodating cup parts capable of accommodating the solder paste therein are formed in the substrate to increase an adhesion surface area, thereby making it possible to improve an adhesion property and to guide the solder paste in a direction that becomes distant from an electrode separation line, thereby making it possible to prevent a short-circuit phenomenon. In addition, the first and second pads of the light emitting device may directly contact the substrate at the time of seating the light emitting device, thereby making it possible to accurately arrange a light emitting axis, and the light emitting device is firmly fused to the bonding media in the accommodating cup parts, such that a fusion path is improved, thereby making it possible to prevent a chip lift defect. Therefore, a yield of a product may be increased and performance of the product may be improved.