Patent Publication Number: US-2013248905-A1

Title: Led package and method of manufacturing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of Korean Patent Application No. 10-2012-0029405, filed on Mar. 22, 2012, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a light-emitting diode (LED) package and a method of manufacturing the same, and more particularly, to an LED package having improved electrical connection with an external power source and a method of manufacturing the LED package. 
     BACKGROUND 
     A light-emitting diode (LED) is a semiconductor device for converting electrical energy into light energy and is formed of a compound semiconductor that emits light with a particular wavelength according to an energy band gap. LEDs have been used in various fields such as lighting and display fields, and the like. 
     LEDs are used in the form of a package of a required type according to the purpose of use. In general, an LED package is configured in such a way that an LED chip is mounted on a substrate on which an electrode pattern is formed and a lens is disposed to cover the LED chip. In this case, the lens is used to control the brightness and view angle of light emitted from the LED package. In general, the lens is formed on the substrate by using a method in which a mold is disposed on the substrate, a transparent resin is injected into the mold, and then the transparent resin is hardened. Examples of the method include injection molding, compression molding, and the like. 
     However, when such a molding method is used, a gap is occasionally formed between the mold and the substrate, and thus, the transparent resin can leak out of the mold. When the leaking transparent resin reaches a contact terminal of the LED package and partially or entirely covers the contact terminal, it can cause a contact failure when the contact terminal contacts an external power unit. 
     Hence it is desirable to provide an improved light-emitting diode (LED) package and related method of manufacturing which prevent a contact failure of a contact terminal. 
     SUMMARY 
     The teachings herein alleviate one or more of the above noted problems and provide an improved a light-emitting diode (LED) package that prevents a contact failure of a contact terminal and a method of manufacturing the same. 
     An exemplary method of manufacturing a light-emitting diode (LED) includes preparing a printed circuit board (PCB) including a mounting portion on which an LED chip is mounted, a resin blocking portion formed outside an edge of the mounting portion, and a contact terminal disposed outside of an edge of the resin blocking portion and electrically connected to the LED chip. The method includes preparing a mold including a convex portion defining a cavity in which a transparent resin is filled, and a contact portion constituting an edge of the convex portion. The mold is mounted on the PCB such that the contact portion is disposed inside the resin blocking portion. The transparent resin is filled in the cavity. The transparent resin is blocked from leaking past the resin blocking portion in the direction of the contact terminal. 
     In certain examples, the resin blocking portion protrudes from an upper surface of the PCB or is concaved on the upper surface of the PCB. 
     The resin blocking portion may be continually formed along an edge of the contact portion. 
     The resin blocking portion may be formed to have a protrusion height that is less than or equal to a protrusion height of the contact portion. 
     The resin blocking portion may be formed by using any one of a photolithography method and a screen printing method. 
     The PCB may be configured such that a phosphor is disposed on the LED chip. 
     According to another aspect of the present teachings, an LED package is provided. The LED package includes a PCB and an LED chip mounted on the PCB. A contact terminal is electrically connected to the LED chip. A lens is disposed on the LED chip to cover the LED chip. A resin blocking portion is disposed on an upper surface of the PCB between an edge of the lens and the contact terminal. 
     The resin blocking portion may be spaced apart from an edge of the lens. 
     The resin blocking portion may be continually formed along an edge of the contact portion. 
     The resin blocking portion may protrude from an upper surface of the PCB or may be concaved on the upper surface of the PCB. 
     A phosphor may be disposed on the LED chip and the lens may cover the phosphor. 
     The lens may have a hemispherical shape. 
     In yet another example, a method of method of manufacturing a light-emitting diode (LED) is provided. The method includes mounting an LED chip on a mounting portion of a printed circuit board (PCB). A contact terminal electrically connected to the LED chip is provided. A resin blocking portion is formed between the mounting portion and the contact terminal. A mold is provided and includes a cavity for containing a transparent resin and a contact portion for contacting an upper surface of the PCB. The mold is mounted on the upper surface of the PCB such that the contact portion is disposed between the resin blocking portion and the LED chip. The transparent resin is filled in the cavity, such that the transparent resin cavity does not reach the contact terminal. 
     According to the above-described aspects of present teachings, the LED package and the method of manufacturing the same can restrict movement of a leaking transparent resin due to a modified structure of an upper surface of a PCB, thereby preventing a contact failure due to the transparent resin. 
     Additional advantages and novel features will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and the accompanying drawings or may be learned by production or operation of the examples. The advantages of the present teachings may be realized and attained by practice or use of various aspects of the methodologies, instrumentalities and combinations set forth in the detailed examples discussed below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawing figures depict one or more implementations in accord with the present teachings, by way of example only, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements. 
         FIG. 1  is a cross-sectional view of an exemplary light-emitting diode (LED) package; 
         FIG. 2  is a plan view of the LED package of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of another exemplary LED package; 
         FIGS. 4A through 4D  are diagram examples for explaining a method of manufacturing an LED package; 
         FIGS. 5A through 5D  are diagram examples for explaining another method of manufacturing an LED package; 
         FIG. 6  is a schematic plan view of an LED package according to Comparative Example 1; and 
         FIG. 7  is a schematic plan view of an LED package according to Example 1. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, numerous specific details are set forth by way of examples in order to provide a thorough understanding of the relevant teachings. However, it should be apparent to those skilled in the art that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings. In the drawings, the thicknesses of layers and regions may be exaggerated for clarity. 
       FIG. 1  is a cross-sectional view of an LED package  10   FIG. 1  illustrates a printed circuit board (PCB)  100 , an LED chip  110 , a contact terminal  130 , a lens  150 , and a resin blocking portion  170 . 
     The LED chip  110  is mounted on the PCB  100 . According to this example, the LED package  10  is a chip-on-board (COB) type LED package  10  in which the LED chip  10  is mounted directly on the PCB  100 , as shown in  FIG. 1 . Since the COB type LED package  10  is mounted directly on the PCB  100 , it is not required to perform a conventional method in which the LED chip  110  is mounted on a lead frame and then a separate process of connecting the lead frame to the PCB  100  is performed. That is, according to this example, by using the COB type LED package  10 , the amount of time and cost required for connection with the PCB  100  after completion of a package may be reduced. 
     In this case, although not illustrated in  FIG. 1 , the LED chip  110  may include an n-type semiconductor layer, an active layer, and a p-type semiconductor layer. When a voltage is applied to the LED chip  110 , electrons of the n-type semiconductor layer and the holes of the p-type semiconductor layer move to the active layer and are recombined with each other. Light is emitted from the active layer due to an energy difference formed when the electrons and the holes are recombined with each other. Although a single LED chip  110  is illustrated in  FIG. 1 , a plurality of LED chips may instead be used. The plurality of LED chips may be arranged in various forms. Example of the arrangement may include a radial form or a linear form. 
     The contact terminal  130  electrically contacts the LED chip  110 . The contact terminal  130  is spaced apart from the LED chip  110  on the PCB  100  and is exposed to the outside. Electrodes of the LED chip  110 , for example, an anode and a cathode may be connected to the contact terminal  130 . However, a connection structure of the contact terminal  130  and the LED chip  110  is not limited to the structure shown in  FIG. 1 . That is, various connection methods may be used according to the structure of the LED chip  110 . The contact terminal  130  that is exposed to the outside may be disposed outside an edge of the resin blocking portion  170  that will be described below. 
     In the example of  FIG. 1 , the lens  150  is disposed on the LED chip  110  and is used to control the brightness and view angle of light emitted from the LED chip  110 . The lens  150  may include a transparent resin, for example, silicon, epoxy, or a combination thereof. 
     The lens  150  may be formed in various forms in consideration of the brightness, view angle, or the like of light. For example, the lens  150  may have a hemispherical shape, as shown in  FIG. 1 . 
     The resin blocking portion  170  in  FIG. 1  is disposed between an edge of the lens  150  and the contact terminal  130 . In addition, the resin blocking portion  170  is formed on an upper surface of the PCB  100 . 
     For example, the resin blocking portion  170  may protrude from the upper surface of the PCB  100 , as shown in  FIG. 1 . A protruding resin blocking portion  171  may be spaced apart from the edge of the lens  150 . The lens  150  is formed of a transparent resin  1500  (see  FIG. 4C ) that is fluid before hardening during the formation of the lens  150 . A portion  1500 ′ (hereinafter, referred to as the leaking transparent resin  1500 ′) of the transparent resin  1500  may leak out of a mold  200  (see  FIG. 4C ). In this case, the protruding resin blocking portion  171  serves as a dam or barrier for preventing movement of the leaking transparent resin  1500 ′, thereby preventing the transparent resin  1500  from reaching the contact terminal  130 . Thus, a contact failure of the contact terminal  130 , which may be caused when the transparent resin  1500  reaches the contact terminal  130 , may be prevented. 
       FIG. 2  is a plan view of the LED package  10  of  FIG. 1 , according to another example The resin blocking portion  170  has a continuous shape by being continually formed along the edge of the lens  150 . In other words, the resin blocking portion  170  has a shape so as to surround an external circumference of a region where the lens  150  contacts the PCB  100 . Thus, movement of the leaking transparent resin  1500 ′ may be effectively prevented regardless of a position of a gap ‘g’ (see  FIGS. 4C and 5C ) that is formed between the mold  200  and the PCB  100  during the formation of the lens  150 . In addition, the resin blocking portion  170  is spaced apart from the lens  150  by a predetermined interval. A region of the upper surface of the PCB  100 , on which the resin blocking portion  170  is spaced apart from the lens  150 , may be used for connection with the mold  200  during the formation of the lens  150 . 
     Referring back to  FIG. 1 , a phosphor  120  may be disposed on the LED chip  110 . The phosphor  120  may be formed by mixing a phosphor material with a resin and may include a phosphor material for converting a wavelength into any one of yellow, red, and green wavelengths. In particular, when the LED chip  110  generates a blue wavelength, a yellow light-emitting phosphor material is used as the phosphor  120 , thereby converting light passing through the lens  150  into white light. 
     The phosphor  120  may be disposed on a mounting portion  101  on which the LED chip  110  is mounted. The mounting portion  101  may be formed in the form of a groove that is concaved on the PCB  100 , as shown in  FIG. 1 , but is not limited thereto. That is, the mounting portion  101  may be embodied in various forms. 
       FIG. 3  is a cross-sectional view of an LED package  10  according to another example. According to this example, the LED package  10  has a substantially similar structure as shown in  FIG. 1 , except that the resin blocking portion  170  is concaved in the PCB  100 . The LED package  10  may include the PCB  100 , the LED chip  110 , the contact terminal  130 , the lens  150 , and a concaved resin blocking portion  173 . 
     The concaved resin blocking portion  173  shown in  FIG. 3  is concaved downwards on an edge of the upper surface of the PCB  100 . The concaved resin blocking portion  173  may be disposed outside an edge of the lens  150  similar to the protruding resin blocking portion  171  of  FIG. 1 . In addition, the concaved resin blocking portion  173  may be disposed inside the contact terminal  130  with respect to the lens  150 . The concaved resin blocking portion  173  may accommodate the leaking transparent resin  1500 ′ (see  FIG. 5C ) that leaks out of the mold  200  (see  FIG. 4C ) during the formation of the lens  150 , thereby preventing the leaking transparent resin  1500 ′ from reaching the contact terminal  130 . In detail, when the transparent resin  1500  leaks out of the mold  200  during the formation of the lens  150 , the leaking transparent resin  1500 ′ is accommodated in the concaved resin blocking portion  173  before reaching the contact terminal  130 . As long as the amount of the leaking transparent resin  1500 ′ that is accommodated in the concaved resin blocking portion  173  does not exceed the volume of the concaved resin blocking portion  173 , the leaking transparent resin  1500 ′ may not reach the contact terminal  130 . Thus, a contact failure of the contact terminal  130 , which may be caused when the leaking transparent resin  1500 ′ reaches the contact terminal  130 , may be prevented. 
     In addition, the concaved resin blocking portion  173  in  FIG. 3  is spaced apart from the lens  150  by a predetermined interval, like the protruding resin blocking portion  171  according to the above-described example is continually formed along the edge of the lens  150 . 
     As a depth of the concaved resin blocking portion  173  is increased, a volume of the concaved resin blocking portion  173 , for accommodating the leaking transparent resin  1500 ′ that leaks out of the mold  200 , is increased. In this case, the depth of the concaved resin blocking portion  173  may be limited such that the concaved resin blocking portion  173  may not contact an electric conductor  131  for connecting the contact terminal  130  and the LED chip  110  to each other. 
       FIGS. 4A through 4D  are exemplary diagrams for explaining a method of manufacturing an LED package  10  The method of manufacturing the LED package  10  may include preparing the PCB  100 , preparing the mold  200 , mounting the mold  200  on the PCB  100 , filling with the transparent resin  1500 , and blocking the leaking transparent resin  1500 ′. Each process step will be described below in more detail. 
       FIG. 4A  shows a case where the PCB  100  and the mold  200  are prepared. The PCB  100  includes the mounting portion  101  on which the LED chip  110  is mounted, the resin blocking portion  170  formed outside the mounting portion  101 , and the contact terminal  130  that is disposed outside the resin blocking portion  170  and is electrically connected to the LED chip  110 . The LED chip  110  emits light when an external voltage is applied to the contact terminal  130 . 
     For example, the resin blocking portion  170  protrudes from the upper surface of the PCB  100 , as shown in  FIG. 4A . The contact terminal  130  is disposed outside the edge of the protruding resin blocking portion  171 . 
     In addition, the phosphor  120  may be coated on the LED chip  110  mounted on the PCB  100 . The phosphor  120  may be formed by mixing a phosphor material with a resin and may include a phosphor material for converting a wavelength into any one of yellow, red, and green wavelengths. In particular, when the LED chip  110  generates a blue wavelength, a yellow light-emitting phosphor material is used as the phosphor  120 , thereby converting light passing through the lens  150  into white light. 
     The mold  200  is a member for forming the lens  150  on the LED chip  110 . The mold  200  includes a convex portion  210  of which an inner circumference surface for fixing a shape of the lens  150  is convex and a contact portion  230  constituting an edge of the convex portion  210 . 
       FIG. 4B  shows an example where the PCB  100  and the mold  200  contact each other. The mold  200  is mounted on the PCB  100  such that the contact portion  230  is disposed inside the protruding resin blocking portion  171 . The mold  200  that contacts the PCB  100  forms a cavity between the convex portion  210  and the PCB  100 . The cavity is sealed by the contact portion  230  that contacts the PCB  100 . In order to increase a sealing degree using the contact portion  230 , a shape of an end portion of the contact portion  230  may be changed. For example, although not illustrated, the end portion of the contact portion  230  is processed to have a sharp shape, thereby reducing a contact area in order to increase a pressing force against the PCB  100 . 
       FIG. 4C  shows an example where the transparent resin  1500  is filled in the mold  200 .  FIG. 4D  shows a case where the mold  200  is separated from the PCB  100  after the transparent resin  1500  is hardened. Referring to  FIG. 4C , the transparent resin  1500  is injected into the convex portion  210 , that is, the cavity through a transparent resin injection port  250  formed in the mold  200 . When the transparent resin  1500  is completely filled in the convex portion  210 , the transparent resin  1500 , that is, the lens  150  may have a desired shape. In this state, when the transparent resin  1500  is hardened in a high-temperature environment, the lens  150  may be formed on the LED chip  110  to have a desired shape. Lastly, as shown in  FIG. 4D , when the mold  200  is separated from the PCB  100 , the LED package  10  is completely manufactured. In this case, a single transparent resin injection port  250  is used, but if necessary, a plurality of transparent resin injection ports may be used. 
     As described above, when the transparent resin  1500  is injected, the contact portion  230  seals a space between the convex portion  210  and the PCB  100 , thereby preventing the transparent resin  1500  from leaking out of the mold  200 . 
     However, as shown in  FIG. 4C , the gap ‘g’ may be formed between the contact portion  230  and the PCB  100  due to various reasons such as manufacturing environments, a planarization difference between regions where the contact portion  230  and the PCB  100  overlap with each other, or the like. The protruding resin blocking portion  171  is formed outside an edge of the contact portion  230  and prevents the leaking transparent resin  1500 ′ from reaching the contact terminal  130  through the gap ‘g’. 
     That is, as described above, during the manufacture of the LED package  10 , the transparent resin  1500  injected into the mold  200  may be primarily blocked by the contact portion  230  formed on the mold  200  and may be secondarily blocked by the protruding resin blocking portion  171  of the PCB  100 , thereby preventing the transparent resin  1500  from reaching the contact terminal  130 . 
     The contact portion  230  of the mold  200  may protrude from the convex portion  210  toward the PCB  100 . An end portion of the contact portion  230  may directly contact the PCB  100 . The protruding resin blocking portion  171  may protrude to have a protrusion height h 2  that is smaller than or equal to a protrusion height h 1  of the contact portion  230  in order to prevent interference with the mold  200 . 
     The protruding resin blocking portion  171  is spaced apart from the contact portion  230  in a horizontal direction and is continually formed along an external circumference of the contact portion  230 . Thus, movement of the leaking transparent resin  1500 ′ may be effectively prevented regardless of a position of the gap ‘g’ that is formed between the contact portion  230  and the PCB  100  during the formation of the lens  150 . 
     The protruding resin blocking portion  171  may be formed by using various methods. For example, the protruding resin blocking portion  171  may be formed by using a photolithography method, a screen printing method, or the like. 
       FIGS. 5A through 5D  are exemplary diagrams for explaining another method of manufacturing an LED package  10  The LED package  10  has a substantially similar structure as in the above-described example for  FIGS. 4A-4D . However, the concaved resin blocking portion  173  is formed on the PCB  100  instead of the protruding resin blocking portion  171 . 
     The concaved resin blocking portion  173  may be disposed outside an edge of the contact portion  230  like the protruding resin blocking portion  171  according to the above-described example. The concaved resin blocking portion  173  prevents the leaking transparent resin  1500 ′ from reaching the contact terminal  130  through the gap ‘g’. In detail, during the formation of the lens  150 , when the transparent resin  1500  leaks out of the mold  200  through the gap ‘g’, the leaking transparent resin  1500 ′ is accommodated in the concaved resin blocking portion  173  before reaching the contact terminal  130 , as shown in  FIG. 5C . As long as the amount of the leaking transparent resin  1500 ′ that is accommodated in the concaved resin blocking portion  173  does not exceed the volume of the concaved resin blocking portion  173 , the transparent resin  1500  may not reach the contact terminal  130 . Thus, a contact failure of the contact terminal  130 , which may be caused when the transparent resin  1500  reaches the contact terminal  130 , may be prevented. 
     That is, during the manufacturing of the LED package  10 , the transparent resin  1500  injected into the mold  200  may be primarily blocked by the contact portion  230  formed on the mold  200  and may be secondarily blocked by the concaved resin blocking portion  173 , thereby preventing the transparent resin  1500  from reaching the contact terminal  130 . 
     The concaved resin blocking portion  173  is spaced apart from the contact portion  230  in a horizontal direction and is continually formed along an external circumference of the contact portion  230 . Thus, movement of the leaking transparent resin  1500 ′ may be effectively prevented regardless of a position of the gap ‘g’ that is formed between the contact portion  230  and the PCB  100  during the formation of the lens  150 . 
     The concaved resin blocking portion  173  may be formed by using various methods. For example, the concaved resin blocking portion  173  may be formed by using a photolithography method. 
     Example 1 
     In this example of manufacturing the LED package  10 , the PCB  100  and the mold  200  are prepared. The LED chip  110  is mounted on the mounting portion  101  of the PCB  100 . The contact terminal  130  is disposed on an edge portion of the PCB  100 . The mold  200  includes the convex portion  210  having a convex shape as an inner shape and the contact portion  230  that contacts the PCB  100 . 
     The PCB  100  and the mold  200  contact each other and then silicon (Si) as the transparent resin  1500  is injected into the convex portion  210  through the transparent resin injection port  250 . After the silicon is complexly filled in the convex portion  210 , the silicon is hardened at a high temperature to form the lens  150  on the PCB  100 . 
     Comparative Example 1 
     As with a conventional method, a PCB has an upper surface on which no step difference between the contact portion  230  of the mold  200  and the contact terminal  130  is formed. 
     Example 1 
     The PCB  100  has an upper surface on which a protrusion between the contact portion  230  of the mold  200  and the contact terminal  130  is formed to have a height of about 30 μm and the protruding resin blocking portion  171  is formed of UV ink. The protruding resin blocking portion  171  is formed by using a photolithography method. 
       FIG. 6  is a schematic plan view of the LED package  10  according to Comparative Example 1.  FIG. 7  is a schematic plan view of the LED package  10  according to Example 1. 
     In the LED package  10  according to Comparative Example 1, silicon  1500 ′ is shown leaking through the gap ‘g’ (see  FIG. 4C ) formed between the mold  200  and the PCB  100  and reaching the contact terminal and thus contaminating the contact terminal  130 , as shown in  FIG. 6 . 
     However, in the LED package  10  according to Example 1, although the silicon  1500 ′ partially leaks out of the mold  200 , movement of the silicon  1500 ′ is restricted by the protruding resin blocking portion  171 . Thus, it is confirmed that the silicon  1500 ′ does not reach the contact terminal  130 . That is, the silicon  1500 ′ that leaks through the gap ‘g’ in this Example 1 does not contaminate the contact terminal  130 . Example 1 was repeated about 180 times by using an injection molding method and repeated about 252 times by using a compression molding method. However, it is confirmed with each repeated example, that the silicon  1500 ′ that leaks out of the mold  200  does not reach the contact terminal  130  at all. 
     While the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present teachings.