Abstract:
A light emitting device including a substrate including an entire top surface that is flat, a light emitting diode on the substrate, a lead frame disposed on the flat top surface of the substrate, the lead frame electrically connected to the light emitting diode, a dam member disposed on the substrate and being adjacent to the light emitting diode, the dam member having a circular configuration which has an opening, a first member disposed on the light emitting diode, the first member including a fluorescent substance to convert a light emission spectrum of light from the light emitting diode, a second member disposed in the opening of the dam member, a circumference of the second member being defined by the dam member and a lens disposed on the second member is provided.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a Continuation of co-pending U.S. application Ser. No. 11/849,097 filed on Aug. 31, 2007, which claims priority under 35 U.S.C. 119 and 35 U.S.C. 365 to Korean Patent Application No. 10-2006-0084901 filed on Sep. 4, 2006. The contents of all of these applications are hereby expressly incorporated by reference as fully set forth herein in their entireties. 
     
    
     BACKGROUND 
       [0002]    Embodiments relates to a light emitting device and manufacturing method thereof. 
         [0003]    LEDs (Light Emitting Diodes) constitute a light emission source by using GaAs, AlGaAs, GaN, InGaN or InGaAlP-based compound semiconductor materials, thereby producing various colors. 
         [0004]    Such LEDs have been packetized and used as light emission devices. Further, the LEDs have been used as light sources in various fields such as a lightening indicator, a character indicator and an image indicator. 
       SUMMARY 
       [0005]    The embodiment provides a light emitting device, in which an LED (light emitting diode) is sealed by a molding member having a double sealing structure, and a manufacturing method thereof. 
         [0006]    The embodiment provides a light emitting device, in which a lens adheres before a molding member having a double sealing structure is cured and thus the lens can be adhered with stability, and a manufacturing method thereof. 
         [0007]    The embodiment provides a light emitting device comprising: a substrate; a light emitting diode on the substrate; a molding member sealing the light emitting diode in a double sealing structure and comprising a flat upper surface. 
         [0008]    The embodiment provides a light emitting device comprising: a substrate; a light emitting diode on the substrate; a first molding member sealing the light emitting diode; a second molding member on the first molding member; and a lens adhering on the second molding member. 
         [0009]    The embodiment provides a method for manufacturing a light emitting device, the method comprising the steps of: mounting a light emitting diode on a substrate; sealing the light emitting diode by using a molding member comprising a double sealing structure; and adhering a lens onto the molding member and curing the molding member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a side sectional view showing a light emitting device according to a first embodiment; 
           [0011]      FIGS. 2 to 5  are sectional views showing the procedure for manufacturing a light emitting device according to a first embodiment; 
           [0012]      FIG. 6  is a side sectional view showing a light emitting device according to a second embodiment; and 
           [0013]      FIG. 7  is a flow diagram showing the procedure for manufacturing a light emitting device according to an embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0014]    Hereinafter, a light emitting device according to an embodiment will be described in detail with reference to the accompanying drawings. 
         [0015]      FIG. 1  is a side sectional view showing a light emitting device according to a first embodiment. 
         [0016]    Referring to  FIG. 1 , the light emitting device  100  comprises a substrate  110 , a LED  120 , a first molding member  130 , a second molding member  140  and a lens  150 . 
         [0017]    The substrate  110  comprises a material such as a MCPCB (Metal Core Printed Circuit Board), a FR-4, and a CEM (Composite Epoxy materials grade) PCB. Further, the substrate  110  may also be formed in the form of a COB (chip on board). 
         [0018]    Multiple lead frames  112  and  114  are formed on the substrate  110 . The lead frames  112  and  114  are electrically opened to each other and electrically connected to the LED  120 . Reflective material such as Ag and Al can also be coated on or attached to the surfaces of the lead frames  112  and  114 . 
         [0019]    The LED  120  is fixed to any one of the lead frames  112  and  114 , and is connected to each lead frame  112  and  114  through a wire  122 . The LED  120  can be connected the lead frames  112  and  114  through one wire or in a flip manner. However, the embodiment is not limited thereto. 
         [0020]    The LED  120  can be realized selectively using GaAs, AlGaAs, GaN, InGaN and/or InGaAlP-based compound semiconductor materials. Further, the LED  120  can comprise at least one of red, green and blue LED chips. 
         [0021]    A dam part  116  is formed on the substrate  110 . The dam part  116  can be formed on the substrate  110  in the form of a dam or a bank having a circular configuration or a polygonal loop configuration by using a non-conductive material such as resin. 
         [0022]    The molding members  130  and  140  seal the LED  120  in a double sealing structure. Such molding members  130  and  140  are formed in the form of a circular column or a polygonal column in the inner side of the dam part  116 . 
         [0023]    The first molding member  130  is formed on and around the LED  120  and the second molding member  140  is formed on the first molding member  130 . The first and second molding members  130  and  140  can comprise resin such as epoxy or silicon or material similar to the resin. 
         [0024]    The first molding member  130  is formed in the form of a convex lens. The second molding member  140  is formed on the first molding member  130  in the form of a circular column or a polygonal column, and has a flat upper surface. 
         [0025]    The first molding member  130  seals the LED  120 , the wire  122  and a bonding region. The wire  122  may also be sealed in the first molding member  130  or the second molding member  140 . 
         [0026]    A fluorescent substance can be added to at least one of the first and second molding members  130  and  140 . For instance, a fluorescent substance  170  can be added to the first molding member  130 . For example, a yellow fluorescent substance that emits a yellow light by converting a part of a blue light of a blue LED chip into the yellow light may also be added. 
         [0027]    First and second fluorescent substances may be added to the first molding member  130  and/or the second molding member  140 , respectively. The first and second fluorescent substances may be fluorescent substances having similar light emitting spectrums, i.e. yellow fluorescent substances. Further, the first and second fluorescent substances may be fluorescent substances having different light emission spectrums, i.e. a red fluorescent substance and a green fluorescent substance. Such fluorescent substances may comprise red, yellow, green and blue fluorescent substances. The embodiment is not limited thereto. 
         [0028]    The first molding member  130  can be formed using liquid resin of about 0.01 g, and the second molding member  140  can be formed using liquid resin of about 0.02 g to 0.04 g. That is, the second molding member  140  has a volume larger than that of the first molding member  130 . 
         [0029]    The second molding member  140  may comprise material identical to that of the lens  150 , or material such as resin (e.g. epoxy, silicon and phenyl) having optical (refractive index), physical and chemical characteristics similar to the lens  150 . 
         [0030]    The lens  150  adheres onto the second molding member  140 . The lens  150  has hemispherical shape and integrally adheres to the flat upper surface of the second molding member  140 . Such a lens  150  is integrally adhered to the second molding member  140  without using an additional adhesion member when the second molding member  140  is cured. The lens  150  may also comprise a hemispherical convex shape or a lens having a concave-convex shape formed thereon. The embodiment is not limited thereto. 
         [0031]    As described above, the optical characteristics of the lens  150  may not be degraded by considering the physical and optical characteristics of the second molding member  140  and the lens  150 . Further, the lens  150  can be firmly adhered to the second molding member  140 . 
         [0032]      FIGS. 2 to 5  are sectional views showing the procedure for manufacturing the light emitting device according to the first embodiment. 
         [0033]    Referring to  FIG. 2 , the LED  120  is fixed to the lead frame  114  on the substrate  110  and is connected to the lead frames  112  and  114  through the wire  122 . 
         [0034]    The dam part  116  is formed on the lead frame  114  and around the LED  120 . The dam part  116  is formed on the substrate  110  in the form of a dam or a bank having a circular configuration or a polygonal loop configuration by using non-conductive material such as resin. 
         [0035]    Referring to  FIG. 3 , the first molding member  130  is dispensed on and around the LED  120 . At this time, the first molding member  130  has a convex lens shape in the inner side of the dam part  116 . 
         [0036]    A predetermined amount (e.g. 0.01 g) of the first molding member  130  comprising liquid resin such as epoxy or silicon is dispensed, thereby sealing the LED  120  and the peripheral area of the LED  120 . The first molding member  130  is cured using a thermosetting method. At this time, the thermosetting temperature is resin curing temperature. For example, the first molding member  130  is heated at the temperature of about 150° C. 
         [0037]    The first dispensed molding member  130  is formed in the inner side of the dam part  116  to seal the LED  120 , the wire  122  and the wire bonding region. 
         [0038]    Referring to  FIG. 4 , the second molding member  140  is molded on the first molding member  130 . The second molding member  140  is molded after the first molding member  130  is cured, so that bubbles can be prevented from being formed between the first molding member  130  and the second molding member  140 . 
         [0039]    The second molding member  140  is molded on the first molding member  130  by using a predetermined amount (e.g. 0.02 g to 0.04 g) of liquid resin. The second molding member  140  may comprise material the same as that of the first molding member  130 , e.g. resin such as epoxy or silicon. 
         [0040]    The second molding member  140  is formed in the inner side of the dam part  160 , is formed in the form of a circular column or a polygonal column, and has a flat upper surface. Such first and second molding members  130  and  140  can selectively use a dispensing molding method using a syringe, an insert molding method or a transfer molding method. 
         [0041]    Further, a fluorescent substance (not shown) may be added to at least one of the first and second molding members  130  and  140 . For example, at least one of yellow, red, blue and green fluorescent substances may be added to the first molding member  130  or/and the second molding member  140 . The embodiment is not limited thereto. 
         [0042]    Referring to  FIG. 5 , the lens  150  having a hemispherical shape is adhered onto the second molding member  140 . The lens  150  is integrally adhered onto the second molding member  140 . To this end, the lens  150  is safely seated to the flat upper surface of the second molding member  140  before the second molding member  140  is cured, and then the second molding member  140  is cured. The curing temperature of the second molding member  140  is resin curing temperature, e.g. about 150° C. 
         [0043]    Then, the lens  150  is integrally fixed on the second molding member  140 , thereby completing fabrication of the light emitting diode package. Further, the lens  150  is adhered on the second molding member  140  with structural stability, so that that the lens  150  can be firmly attached to the second molding member  140  and the optical characteristics of the lens  150  may not be degraded when the lens  150  is used. 
         [0044]    The upper surface of the second molding member  140  and the bottom surface of the lens  150  may have the same area or different areas. For example, the upper surface of the second molding member  140  may have a diameter larger than that of the bottom surface of the lens  150 . Further, the second molding member  140  may use material having optical, physical and chemical characteristics the same as or similar to those of the lens  150 . 
         [0045]      FIG. 6  is a side sectional view showing a light emitting device according to a second embodiment. 
         [0046]    Referring to  FIG. 6 , the light emitting device  200  comprises a substrate  210  having a groove  216 , a plurality of lead frames  212  and  214 , a LED  220 , a first molding member  230 , a second molding member  240  and a lens  250 . 
         [0047]    The groove  216  formed on the substrate  210  may have a circular shape or a polygonal shape and can be formed through injection molding. However, the embodiment is not limited thereto. 
         [0048]    The lead frames  212  and  214  are electrically opened in the groove  216 , and the LED  220  is mounted on the lead frames  212  and  214  in the groove  216 . The lead frames  212  and  214  are slantingly formed along the inner peripheral surface of the groove  216 , and reflective material, e.g. Ag or Al, may also be coated on the surfaces of the lead frames  212  and  214 . 
         [0049]    The first molding member  230  is dispensed on the groove  216  and then cured. Then, the second molding member  240  is dispensed on the first molding member  230 . The upper surface of the second molding member  240  is flat, and the flat upper surface is formed on the same plane with the upper surface of the substrate  210 . As described above, the second molding member  240  is formed after the first molding member  230  is cured, so that bubbles can be prevented being formed between the first molding member  230  and the second molding member  240 . 
         [0050]    The first molding member  230  and the second molding member  240  comprise liquid resin such as epoxy or silicon, and are cured using a thermosetting method at the temperature of about 150. The second molding member  240  may have amount equal to or greater than that of the first molding member  230 . For example, the amount of the second molding member  240  is at least twice the amount of the first molding member  230 . 
         [0051]    The first and second molding members  230  and  240  can be molded using a dispensing molding method using a syringe, an insert molding method or a transfer molding method. 
         [0052]    Further, a fluorescent substance (not shown) may be added to at least one of the first and second molding members  230  and  240 . For example, at least one of yellow, red, blue and green fluorescent substances may be added to the first molding member  230  or/and the second molding member  240 . The embodiment is not limited thereto. 
         [0053]    The lens  250  adheres onto the second molding member  240 . The lens  250  has a hemispherical convex shape and adheres onto the upper surface of the second molding member  240 . In detail, the lens  250  adheres onto the upper surface of the second molding member  240  during the curing process of the second molding member  240 . 
         [0054]    As described above, the molding members  230  and  240  are molded on the LED  220  in a double sealing structure, and then the lens  250  integrally adheres onto the upper surface of the second molding member  240 , thereby completing fabrication of the light emitting diode package. 
         [0055]      FIG. 7  is a flow diagram showing the procedure for manufacturing the light emitting device according to the embodiment. 
         [0056]    Referring to  FIG. 7 , the LED is mounted on the lead frame on the substrate (S 101 ). The substrate may have a flat structure or a groove shape. 
         [0057]    Liquid resin is primarily molded on and around the LED to form the first molding member (S 103 ). Such a first molding member uses liquid resin such as epoxy or silicon and is cured at a predetermined temperature (S 105 ). 
         [0058]    Liquid resin is secondarily molded on the first molding member to form a second molding member (S 107 ). 
         [0059]    At this time, a hemispherical convex lens is adhered onto the flat upper surface of the second molding member before the second molding member is cured (S 109 ). Then, the second molding member is cured at a predetermined temperature (S 111 ), thereby completing fabrication of the LED package (S 113 ). 
         [0060]    The second molding member can comprise resin the same as or different from that of the first molding member. Further, since the second molding member can use material having the physical and chemical characteristics the same as or similar to those of the lens, the optical characteristics of the lens may not be degraded when the lens is used. Furthermore, the lens can be fixed with structural stability. 
         [0061]    It will be understood that when an element is referred to as being ‘on’ or “under” another element, it can be directly on/under the element, and one or more intervening elements may also be present. 
         [0062]    Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
         [0063]    Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.