Patent Publication Number: US-2023141035-A1

Title: Ultraviolet (uv) light source and method of manufacturing the same

Description:
CROSS-REFERENCE TO THE RELATED APPLICATION 
     This application is based on and claims priority from Korean Patent Application No. 10-2021-0154291, filed on Nov. 10, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. 
     BACKGROUND 
     Embodiments of the present disclosure relate to an ultraviolet (UV) light source and a method of manufacturing the UV light source. 
     Light-emitting diode (LED) chips and LED packages including LED chips have several advantages, such as low power consumption, high brightness, long lifespan, and the like, and thus, areas of use thereof as light sources have gradually increased. 
     Recently, due to the pandemic situation that has been going on since 2020, there is an increasing interest in UV LEDs used for sterilization and disinfection of air, water, or the like. 
     According to the related art, there has been a large number of applications using mercury UV lamps. UV LEDs, which have been recently developed, have a smaller volume, lighter weight, more compact structures, and five or more times longer lifespan than mercury UV lamps. UV LEDs have more freedom with regard to emission wavelengths, lower heat emission, and better energy efficiency than mercury lamps. In addition, UV LEDs do not generate ozone, which is harmful to humans and the environment, and do not require heavy metals such as mercury or the like. 
     SUMMARY 
     Embodiments of the present disclosure provide an ultraviolet (UV) light source, which has improved heat dissipation and light extraction efficiency, and a method of manufacturing the UV light source. 
     According to embodiments of the present disclosure, an ultraviolet (UV) light source is provided. The UV light source includes: a lower housing; an upper housing coupled to the lower housing, the upper housing including a plate portion and a sidewall protruding from the plate portion; a substrate coupled to the upper housing; a light-emitting diode (LED) package on the substrate; a waterproof coating layer on at least a portion of the substrate; and a first waterproof layer between the waterproof coating layer and the upper housing. The LED package includes: an LED chip configured to generate UV light; and a transparent layer including a lower surface facing the LED chip, an upper surface opposite to the lower surface, and a lateral surface connecting the upper surface to the lower surface, wherein at least a portion of the upper surface of the transparent layer is exposed from the waterproof coating layer, and wherein the transparent layer is configured to directly contact a sterilization-target fluid. 
     According to embodiments of the present disclosure, a UV light source is provided. The UV light source includes: an upper housing including a plate portion and a sidewall protruding from the plate portion; a substrate coupled to the upper housing; a light-emitting diode (LED) chip on the substrate and including a transparent layer; a waterproof coating layer on the substrate and at least a portion of the LED chip; and a first waterproof layer between the waterproof coating layer and the upper housing, wherein at least a portion of an upper surface of the transparent layer is exposed from the waterproof coating layer, such that the LED chip is configured to generate UV light that is directly transferred to a sterilization-target fluid without passing through the waterproof coating layer. 
     According to embodiments of the present disclosure, a UV light source is provided. The UV light source includes: an upper housing including a plate portion and a sidewall protruding from the plate portion; a substrate coupled to the upper housing; a light-emitting diode (LED) package on an upper surface of the substrate and including an LED chip configured to generate UV light; a waterproof coating layer on at least a portion of the upper surface of the substrate; a first waterproof layer between the substrate and the upper housing; and a connector connected to the substrate and providing a path for drive power to the LED chip. The LED package further includes: a base layer including a plate portion, which is overlapped with a lower surface of the LED chip, and a dam portion, which is overlapped with a lateral surface of the LED chip; and a transparent layer on the dam portion of the base layer, the transparent layer including a lower surface facing the LED chip, an upper surface opposite to the lower surface of the transparent layer, and a lateral surface connecting the upper surface of the transparent layer to the lower surface of the transparent layer. 
     According to embodiments of the present disclosure, a method of manufacturing a UV light source is provided. The method includes: mounting a light-emitting diode (LED) package on a first side of a substrate; providing a waterproof coating layer on the substrate and the LED package, by providing a waterproof material and curing the waterproof material; coupling the substrate, on which the LED package is mounted, to an upper housing such that a waterproof layer is arranged between the upper housing and the substrate; providing a molding layer on a second side of the substrate, opposite to the first side; and coupling the upper housing to a lower housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG.  1    is a cross-sectional view of an ultraviolet (UV) light source according to example embodiments; 
         FIG.  2    is an exploded perspective view of the UV light source of  FIG.  1   ; 
         FIG.  3    is a partially enlarged cross-sectional view of a region AA of  FIG.  1   ; 
         FIG.  4    is a cross-sectional view of a light-emitting diode (LED) chip; 
         FIG.  5    is a diagram illustrating a water supplier according to example embodiments; 
         FIG.  6    is a diagram illustrating an air supplier according to example embodiments; 
         FIG.  7 A  is a partial cross-sectional view illustrating a portion of a UV light source according to an example embodiment; 
         FIG.  7 B  is a partial cross-sectional view illustrating a portion of a UV light source according to an example embodiment; 
         FIG.  7 C  is a partial cross-sectional view illustrating a portion of a UV light source according to an example embodiment; 
         FIG.  7 D  is a partial cross-sectional view illustrating a portion of a UV light source according to an example embodiment; 
         FIG.  7 E  is a partial cross-sectional view illustrating a portion of a UV light source according to an example embodiment; 
         FIG.  7 F  is a partial cross-sectional view illustrating a portion of a UV light source according to an example embodiment; 
         FIG.  8 A  is a cross-sectional view illustrating a UV light source according to an example embodiment; 
         FIG.  8 B  is a cross-sectional view illustrating a UV light source according to an example embodiment; 
         FIG.  8 C  is a cross-sectional view illustrating a UV light source according to an example embodiment; 
         FIG.  8 D  is a cross-sectional view illustrating a UV light source according to an example embodiment; 
         FIG.  9    is a cross-sectional view of a UV light source according to example embodiments; 
         FIG.  10    is a partially enlarged cross-sectional view of a region BB of  FIG.  9   ; 
         FIG.  11    is a flowchart illustrating a method of manufacturing a UV light source, according to example embodiments; 
         FIG.  12 A  is a first diagram illustrating a method of manufacturing a UV light source, according to example embodiments; 
         FIG.  12 B  is a second diagram illustrating the method of manufacturing the UV light source, according to example embodiments; and 
         FIG.  12 C  is a third diagram illustrating the method of manufacturing the UV light source, according to example embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, non-limiting example embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Like components are denoted by like reference numerals throughout the specification, and repeated descriptions 
     It will be understood that when an element or layer is referred to as being “over,” “above,” “on,” “below,” “under,” “beneath,” “connected to” or “coupled to” another element or layer, it can be directly over, above, on, below, under, beneath, connected or coupled to the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly over,” “directly above,” “directly on,” “directly below,” “directly under,” “directly beneath,” “directly connected to” or “directly coupled to” another element or layer, there are no intervening elements or layers present. 
       FIG.  1    is a cross-sectional view illustrating an ultraviolet (UV) light source  100  according to example embodiments. 
       FIG.  2    is an exploded perspective view of the UV light source  100  of  FIG.  1   . 
       FIG.  3    is a partially enlarged cross-sectional view of a region AA of  FIG.  1   . 
     Referring to  FIGS.  1  to  3   , the UV light source  100  may include a lower housing  110 , an upper housing  120 , a substrate  130 , a light-emitting diode (LED) package  140 , a waterproof coating layer  150 , a first waterproof layer  161 , a second waterproof layer  165 , securing devices  170 , a molding layer  180 , and a connector  190 . 
     According to example embodiments, the UV light source  100  may be configured to generate and emit UV light. According to example embodiments, the UV light source  100  may be configured to generate and emit UV light in a narrow wavelength band. The UV light source  100  generates only UV light in a narrow wavelength band, which is used for disinfection and sterilization, and thus, energy efficiency of the UV light source  100  may be improved. 
     As a non-limiting example, the UV light source  100  may generate UVC light. As a non-limiting example, a wavelength of light generated by the UV light source  100  may range from about 100 nm to about 280 nm. The UV light source  100  may generate UVA light having a wavelength of about 315 nm to about 400 nm or generate UVB light having a wavelength of about 280 nm to about 320 nm. 
     According to example embodiments, the UV light source  100  may be configured to sterilize and disinfect a fluid such as air and water. According to example embodiments, the UV light source  100  may remove viruses, bacteria, and the like, which are included in a sterilization-target fluid, by generating UV light and irradiating the sterilization-target fluid with the UV light. 
     The lower housing  110  may be coupled to the upper housing  120 . The lower housing  110  may protect the substrate  130  and the LED package  140 . The lower housing  110  and the upper housing  120  may be coupled to a container, such as a water tank or the like, for storing a fluid that is a sterilization target. 
     The lower housing  110  may have a hollow cylinder shape. An inner surface of the lower housing  110  may include a first fastening structure  110 C. The first fastening structure  110 C may include screw threads or spiral grooves. The lower housing  110  may discharge heat generated according to an operation of the UV light source  100 . 
     The lower housing  110  and the upper housing  120  that is described below may each include a metal material or a nonmetal material. As a non-limiting example, the metal material may include at least one from among chromium (Cr), molybdenum (Mo), nickel (Ni), aluminum (Al), and stainless steel. As a non-limiting example, the nonmetal material may include one of glass, quartz, sapphire, polycarbonate, polyamide, polypropylene (PP), polyethylene (PE), polycarbonate (PC), polybutylene terephthalate (PBT), polyoxymethylene (POM, also known as polyacetal), a polyphenylene oxide (PPO) resin, and a modified PPO resin. Here, the modified PPO resin includes a resin obtained by mixing PPO with a polystyrene or polyamide resin, has heat resistance, and stably maintains material properties even at a low temperature. 
     The upper housing  120  may include a plate portion  121  and a sidewall  125 . The upper housing  120  may be coupled to the lower housing  110 . The substrate  130  and the LED package  140  may be arranged in an internal space defined by the plate portion  121  and the sidewall  125  of the upper housing  120 . 
     The plate portion  121  may include a flat surface  121 F, which is substantially a plane, an inner circumferential surface  121 I, which defines an opening  121 O exposing the LED package  140 , and an inclined surface  121 S, which connects the inner circumferential surface  121 I to the flat surface  121 F. The flat surface  121 F may horizontally surround the opening  121 O. 
     The area of the opening  121 O may be greater than the area of the LED package  140 . Accordingly, the opening  121 O may expose an entire upper surface  147 U of a transparent layer  147  of the LED package  140 . A planar shape of the opening  121 O may be similar to a planar shape of the LED package  140 . For example, when the planar shape of the LED package  140  is approximately rectangular, the planar shape of the opening  121 O may be approximately rectangular. 
     The inclined surface  121 S may improve a light extraction efficiency of the UV light source  100  by reflecting light emitted through the opening  1210 . 
     The sidewall  125  may protrude from the plate portion  121 . As a non-limiting example, the sidewall  125  may have an approximately cylindrical shape. A fastening structure  125 C may be provided to an inner surface of the sidewall  125 . The fastening structure  125 C may include screw threads or spiral grooves. The fastening structure  125 C may be coupled to the first fastening structure  110 C. 
     The substrate  130  may be coupled to the upper housing  120 . The substrate  130  may be secured to the upper housing  120  by at least one of the securing devices  170 , such as a bolt or the like. The securing devices  170  may be secured to the upper housing  120  in a press fit manner through the substrate  130  and the first waterproof layer  161 . 
     According to example embodiments, the substrate  130  may be a printed circuit board (PCB). The substrate  130  may be designed by, for example, a surface mounting technique. The substrate  130  may include a substrate base  131 , conductive patterns including pads  133 , and an insulating layer  132  surrounding the conductive patterns. 
     The substrate base  131  may include aluminum. Because the substrate base  131  including aluminum has high heat conductivity, the substrate base  131  including aluminum may effectively discharge heat generated by the LED package  140 . Accordingly, an operating temperature of the UV light source  100  may be decreased, and the lifespan of the UV light source  100  may be increased. In addition, because the LED package  140  does not require a separate radiator, the volume of the UV light source  100  may be reduced, and the mechanical strength of the UV light source  100  may be improved. The substrate base  131  may have, but is not limited to, a coefficient of thermal expansion of about 20.0 parts per million (ppm) or more. 
     According to example embodiments, the conductive patterns including the pads  133  may each include a conductive material such as copper or the like. The insulating layer  132  may include, for example, a photosensitive resist. One of the pads  133  may be connected to a cathode of the LED package  140 , and another one of the pads  133  may be connected to an anode of the LED package  140 . 
     According to example embodiments, the pads  133  may provide paths for supplying operating power and signals to the LED package  140 . According to example embodiments, the pads  133  may provide paths for discharging heat generated by the LED package  140 . 
     The LED package  140  may be mounted on the substrate  130 . A plurality of the LED package  140  may be secured and connected to the substrate  130  by external connection solders  148 . The external connection solders  148  may be respectively connected to the pads  133 . 
     Heretofore, although the substrate  130  including the substrate base  131  made of a ceramic material has been described, this is merely a non-limiting example and does not limit the scope of the present disclosure in any way. 
     Those of ordinary skill in the art would also recognize, based on descriptions made herein, that the present disclosure also includes an embodiment where the substrate  130  is a metal-core PCB (MCPCB) including copper, an embodiment where the substrate  130  is a flexible PCB that is flexible and easily transformable into various shapes, and an embodiment where the substrate  130  is a general FR4-type PCB. 
     The LED package  140  may be mounted on the substrate  130 . The LED package  140  may include a base layer  141 , pads  142 , through-electrodes  143 , external connection pads  144 , an LED chip  145 , solders  146 , and a transparent layer  147 . 
     As a non-limiting example, the LED package  140  may be mounted on the substrate  130  by the external connection solders  148 . However, embodiments of the present disclosure are not limited thereto, and the LED package  140  may be mounted on the substrate  130  by eutectic bonding, and in this case, the external connection solders  148  may be omitted. 
     The base layer  141  may include, for example, an insulating material such as a ceramic material. The ceramic material may include low temperature co-fired ceramic (LTCC) or high temperature co-fired ceramic (HTCC). As a non-limiting example, the base layer  141  may include AlN, Al 2 O 3 , and the like. According to example embodiments, the base layer  141  may have a high heat conductivity of 140 W/m·K or more. Accordingly, the base layer  141  may effectively discharge heat generated by the LED chip  145 . 
     The base layer  141  may include a plate portion  141 P, which covers a lower surface of the LED chip  145 , and a dam portion  141 D, which covers a lateral surface of the LED chip  145 . According to example embodiments, the base layer  141  may improve the light extraction efficiency of the UV light source  100  by reflecting light generated by the LED chip  145 . 
     The pads  142 , the through-electrodes  143 , the external connection pads  144 , and the external connection solders  148  may provide electrical paths for the LED chip  145 . According to example embodiments, signals and power for driving the LED chip  145  may be provided through the pads  142 , the through-electrodes  143 , the external connection pads  144 , and the external connection solders  148 . 
     The pads  142  may be provided onto an upper surface of the base layer  141 . The external connection pads  144  may be provided onto the lower surface of the base layer  141 . The through-electrodes  143  may pass through the base layer  141  and be connected to the respective pads  142  and the respective external connection pads  144 . One of the pads  142  may be connected to an anode of the LED chip  145 , and another one of the pads  142  may be connected to a cathode of the LED chip  145 . 
     The LED chip  145  may be coupled to the base layer  141  by eutectic bonding. The LED chip  145  may be coupled to the pads  142  by the solders  146 . 
     The transparent layer  147  may be arranged on the dam portion  141 D of the base layer  141 . The transparent layer  147  may include a material having high transmittance with respect to ultraviolet light including UVC. According to example embodiments, the transparent layer  147  may include glass, quartz, or the like. 
     According to example embodiments, the transparent layer  147  may be secured to the dam portion  141 D of the base layer  141 . In one example, a waterproof bonding agent may be provided between the transparent layer  147  and the dam portion  141 D of the base layer  141 . In another example, the transparent layer  147  may be coupled to the dam portion  141 D of the base layer  141  by a hermetic seal. The hermetic seal may be provided by fusion bonding between the transparent layer  147  and the dam portion  141 D of the base layer  141 . The hermetic seal may prevent a fluid such as water from flowing between the transparent layer  147  and the base layer  141 . 
     A lower surface  147 L of the transparent layer  147  may face the LED chip  145 . An upper surface  147 U of the transparent layer  147  may be opposite to the lower surface  147 L of the transparent layer  147 . The upper surface  147 U of the transparent layer  147  may contact a sterilization-target fluid. A lateral surface  147 S of the transparent layer  147  may connect the upper surface  147 U to the lower surface  147 L. 
     Hereinafter, a structure of the LED chip  145  will be described in more detail with reference to  FIG.  4   . 
       FIG.  4    is a cross-sectional view illustrating the LED chip  145 . 
     Referring to  FIG.  4   , the LED chip  145  may include a transparent layer  1451 , a buffer layer  1452 , a first conductivity-type nitride semiconductor layer  1453 , an active layer  1454 , second conductivity-type nitride semiconductor layers  1455  and  1456 , a first electrode  1457 , and a second electrode  1458 . 
     The transparent layer  1451  may be transparent with respect to light generated by the LED chip  145 . As a non-limiting example, the transparent layer  1451  may include sapphire and may be a portion of a growth substrate for forming the LED chip  145 . In the transparent layer  1451  for growth including sapphire, a sapphire substrate is a crystal having electrical insulating properties and having hexa-rhombo R3c symmetry, respectively has lattice constants of 13.001 Å and 4.758 Å in c-axis and a-axis directions, and has a C (0001) plane, an A (1120) plane, an R (1102) plane, and the like. In this case, a C-plane of sapphire substrate allows the growth of a nitride thin layer thereon to be relatively facilitated and is mainly used as a substrate for nitride growth due to stability thereof at high temperature. 
     In another example, the transparent layer  1451  may be provided separately from the growth of a nitride semiconductor layer, and the LED chip  145  may be manufactured based on a growth substrate including a material such as Si, SiC, MgAl 2 O 4 , MgO, LiAlO 2 , LiGaO 2 , GaN, or the like. 
     The buffer layer  1452  may be arranged on the transparent layer  1451 . The buffer layer  1452  may alleviate lattice defects of the first conductivity-type nitride semiconductor layer  1453 , the active layer  1454 , and the second conductivity-type nitride semiconductor layers  1455  and  1456 , which are provided based on the growth substrate. The buffer layer  1452 , for example, may improve crystallinity of the first conductivity-type nitride semiconductor layer  1453  by alleviating a difference in lattice constant between the growth substrate including sapphire and the first conductivity-type nitride semiconductor layer  1453  including gallium nitride. 
     The buffer layer  1452  may include an undoped semiconductor material. As a non-limiting example, the buffer layer  1452  may include undoped GaN, AlN, InGaN, or the like and may be manufactured at a low temperature of about 500° C. to about 600° C. The buffer layer  1452  may have a thickness of tens to hundreds of angstrom (Å). Here, the buffer layer  1452  being undoped means that the buffer layer  1452  has not undergone a separate impurity doping process. The buffer layer  1452  may include impurities at an intrinsic concentration level even when undoped. For example, when a gallium nitride layer is grown by metal organic chemical vapor deposition (MOCVD), the gallium nitride layer may include Si or the like at a level of about 10 14 /cm 3  to about 10 18 /cm 3 . According to embodiments, the buffer layer  1452  may be omitted in some cases. 
     The first conductivity-type nitride semiconductor layer  1453  may be arranged on the buffer layer  1452 , the active layer  1454  may be arranged on the first conductivity-type nitride semiconductor layer  1453 , and the second conductivity-type nitride semiconductor layers  1455  and  1456  may be arranged in the stated order on the active layer  1454 . 
     The first conductivity-type nitride semiconductor layer  1453  may be an n-type nitride semiconductor layer, and each of the second conductivity-type nitride semiconductor layers  1455  and  1456  may be a p-type nitride semiconductor layer. According to some embodiments, the first conductivity-type nitride semiconductor layer  1453  may be a p-type nitride semiconductor layer, and each of the second conductivity-type nitride semiconductor layers  1455  and  1456  may be an n-type nitride semiconductor layer. 
     According to some embodiments, each of the first conductivity-type nitride semiconductor layer  1453  and the second conductivity-type nitride semiconductor layers  1455  and  1456  may include a material satisfying a compositional formula of Al x In y Ga (1-x-y) N (where 0≤x≤1, 0≤y≤1, 0≤x+y≤1). For example, each of the first conductivity-type nitride semiconductor layer  1453  and the second conductivity-type nitride semiconductor layers  1455  and  1456  may include a material such as GaN, AlGaN, InGaN, AlInGaN, or the like. As a non-limiting example, the first conductivity-type nitride semiconductor layer  1453  may include AlGaN doped with an n-type dopant, the second conductivity-type nitride semiconductor layer  1455  may include AlGaN doped with a p-type dopant, and the second conductivity-type nitride semiconductor layer  1456  may include GaN doped with a p-type dopant. 
     A plurality of the active layer  1454  may be arranged between the first conductivity-type nitride semiconductor layer  1453  and the second conductivity-type nitride semiconductor layers  1455 . The plurality of the active layer  1454  may emit light having certain energy by recombination of electrons and holes. Each active layer from among the plurality of the active layer  1454  may include a material having an energy band gap that is less than an energy band gap of each of the first conductivity-type nitride semiconductor layers  1453  and the second conductivity-type nitride semiconductor layer  1455 . For example, when each of the first conductivity-type nitride semiconductor layer  1453  and the second conductivity-type nitride semiconductor layer  1455  includes a GaN-based compound semiconductor, each active layer from among the plurality of the active layer  1454  may include an InGaN-based compound semiconductor having an energy band gap that is less than an energy band gap of GaN. According to some embodiments, the plurality of the active layer  1454  may include a multiple quantum well (MQW) structure in which quantum well layers and quantum barrier layers are alternately stacked. According to some embodiments, the plurality of the active layer  1454  may include an alternate stacking structure of InGaN/GaN. However, embodiments of the present disclosure are not limited thereto, and the plurality of the active layer  1454  may include a single quantum well (SQW) structure. 
     The first electrode  1457  may be a cathode of the LED chip  145 . The first electrode  1457  may provide an electrical path with respect to the first conductivity-type nitride semiconductor layer  1453 . The first electrode  1457  may contact the first conductivity-type nitride semiconductor layer  1453 . 
     The second electrode  1458  may be an anode of the LED chip  145 . The second electrode  1458  may provide an electrical path with respect to the second conductivity-type nitride semiconductor layers  1455  and  1456 . The second electrode  1458  may contact the second conductivity-type nitride semiconductor layer  1456 . 
     Each of the first electrode  1457  and the second electrode  1458  may include an Ohmic metal layer, a reflective metal layer, and an under bump metallurgy (UBM) layer. 
     The Ohmic metal layer may provide Ohmic contact to each of the first conductivity-type nitride semiconductor layer  1453  and the second conductivity-type nitride semiconductor layer  1456 . The Ohmic metal layer may include nickel, platinum, gold, and the like. 
     The reflective metal layer may improve optical efficiency of the LED chip  145  by reflecting UV light generated by the active layer  1454  (or active layers). The reflective metal layer may include at least one metal selected from the group consisting of copper (Cu), aluminum (Al), nickel (Ni), silver (Ag), gold (Au), platinum (Pt), tin (Sn), lead (Pb), titanium (Ti), chromium (Cr), paladium (Pd), indium (In), and zinc (Zn), a metal alloy, carbon (C), and the like. 
     The UBL layer may include, for example, grooves for coupling to the solders  146  (see  FIG.  3   ). Accordingly, the first electrode  1457  and the second electrode  1458  may respectively contact the solders  146  (see  FIG.  3   ). 
     Referring again to  FIGS.  1  to  3   , the waterproof coating layer  150  may cover an upper surface of the substrate  130  and a lateral surface of the LED package  140 . The waterproof coating layer  150  may include an encapsulant such as silicone, epoxy, or the like. The waterproof coating layer  150  may isolate the substrate  130 , the LED package  140 , and an electronic component that is mounted on the substrate  130 , from a sterilization-target fluid. 
     The waterproof coating layer  150  may be provided by a dispensing and spraying process. The waterproof coating layer  150  may include silicone, epoxy, and the like. 
     According to example embodiments, the waterproof coating layer  150  may cover the lateral surface  141 S of the base layer  141  and the lateral surface  147 S of the transparent layer  147 . According to example embodiments, the waterproof coating layer  150  may cover the entire lateral surface  147 S of the transparent layer  147 . According to example embodiments, the waterproof coating layer  150  may cover the external connection pads  144  and the external connection solders  148 . 
     According to example embodiments, the waterproof coating layer  150  may expose at least a portion of the upper surface of the LED package  140 . According to example embodiments, the waterproof coating layer  150  may not cover the upper surface of the LED package  140 . 
     According to example embodiments, the waterproof coating layer  150  may expose at least a portion of the upper surface  147 U of the transparent layer  147 . According to example embodiments, the waterproof coating layer  150  may expose the entire upper surface  147 U of the transparent layer  147 . According to example embodiments, the waterproof coating layer  150  may not cover the upper surface  147 U of the transparent layer  147 . According to example embodiments, the waterproof coating layer  150  may not contact the upper surface  147 U of the transparent layer  147 . According to example embodiments, the waterproof coating layer  150  may be apart from the upper surface  147 U of the transparent layer  147 . 
     The waterproof coating layer  150  may include a first portion  150 P 1 , which covers the upper surface of the substrate  130 , and a second portion  150 P 2 , which covers the lateral surface  141 S and the lateral surface  147 S of the LED package  140 . The first portion  150 P 1  may contact the upper surface of the substrate  130 , and the second portion  150 P 2  may contact the lateral surface  141 S and the lateral surface  147 S. As a non-limiting example, the first portion  150 P 1  may have a conformal shape. The first portion  150 P 1  may have a constant thickness. 
     In the present example, the waterproof coating layer  150  may be provided by a dispensing process, a spraying process, an ink-jet process, and the like of a high-viscosity coating material. In the present example, a dynamic viscosity of the coating material for forming the waterproof coating layer  150  may range from about 15000 centipoise (cps) to about 1500000 cps. Accordingly, the second portion  150 P 2  of the waterproof coating layer  150  may have a convex shape. 
     According to example embodiments, UV light of the UV light source  100 , which has passed through the transparent layer  147 , may be directly irradiated onto a sterilization-target fluid such as water, air, and the like without passing through an additional transparent layer. According to example embodiments, the transparent layer  147  may directly contact a sterilization-target fluid such as water, air, and the like. 
     In UV light sources according to the related art, cover windows such as quartz, glass, and the like cover LED packages such that the LED packages are not exposed to fluids. There is a loss of a large amount of light during the process in which UV light emitted from the LED packages passes through an air layer and a transparent layer. 
     According to example embodiments, by covering the substrate  130  and the LED package  140  with the waterproof coating layer  150  that does not cover the upper surface  147 U of the transparent layer  147 , UV light generated by the LED package  140  may be directly transferred to a fluid. Accordingly, a reflection loss generated due to incidence on a cover window and an absorption loss occurring while passing through the cover window may be prevented, and thus, the light extraction efficiency of the UV light source  100  may be improved. 
     In addition, the upper surface  147 U of the transparent layer  147  directly contacts a sterilization-target fluid such as air, water, and the like, and thus, a heat dissipation efficiency of the LED package  140  may be improved. 
     Table 1 shows operating performances of illumination devices as comparison examples according to the related art and the UV light source  100  according to example embodiments. 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Comparison 
                 Comparison 
                 Experimental 
               
               
                   
                 Example 1 
                 Example 2 
                 Example 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 Light extraction efficiency 
                 100 
                 97 
                 116 
               
               
                 Operating temperature 
                 36.3° C. 
                 37.5° C. 
                 33.5° C. 
               
               
                 (30 mA) 
               
               
                 Operating temperature 
                 62.6° C. 
                 66.7° C. 
                 53.4° C. 
               
               
                 (100 mA) 
               
               
                   
               
            
           
         
       
     
     In Table 1, in the illumination device of Comparison Example 1, an LED package was covered by a cover window, and in the illumination device of Comparison Example 2, an LED chip was directly mounted on a substrate such as a PCB substrate and was covered by a cover window. An illumination device of Experimental Example is substantially the same as the illumination device, that is, the UV light source  100 , described with reference to  FIGS.  1  to  3   . 
     In Table 1, data regarding light extraction efficiencies is dimensionless values normalized such that the light extraction efficiency of the illumination device of Comparison Example 1 becomes 100. From Table 1, it was confirmed that the light extraction efficiency of the illumination device of Experimental Example was improved by about 16% as compared with the light extraction efficiency of the illumination device of Comparison Example 1. In the case of Comparison Example 2, it was confirmed that the light extraction efficiency was reduced because the LED chip was not packaged by a ceramic substrate or the like. 
     In the case of being driven by a current of 30 mA, it was confirmed that the operating temperature of the illumination device of Experimental Example was decreased by about 7.7% in terms of Celsius temperature as compared with the operating temperature of the illumination device of Comparison Example 1. In addition, in the case of being driven by a current of 100 mA, it was confirmed that the operating temperature of the illumination device of Experimental Example was decreased by about 14.6% in terms of Celsius temperature as compared with the operating temperature of the illumination device of Comparison Example 1. 
     In the case of Comparison Example 2, because the LED chip was directly mounted on the substrate such as a PCB substrate, and thus, the heat dissipation efficiency was decreased, it was confirmed that the respective operating temperatures in driving conditions of 30 mA and 100 mA were increased as compared with Comparison Example 1. 
     From Table 1, it was confirmed that the light extraction efficiency and heat dissipation efficiency of the UV light source  100  according to example embodiments were improved. 
     The first waterproof layer  161  may be arranged between the waterproof coating layer  150  and the upper housing  120 . The first waterproof layer  161  may include, for example, rubber. As the substrate  130  is coupled to the upper housing  120 , the waterproof coating layer  150  and the upper housing  120  may apply a certain pressure to the first waterproof layer  161 . Accordingly, the first waterproof layer  161  may secure the isolation of the substrate  130  and the LED package  140  from a sterilization-target fluid such as water or the like. 
     The substrate  130  and the first waterproof layer  161  may be coupled and secured to the upper housing  120  by the securing devices  170 . 
     The second waterproof layer  165  may be arranged between the plate portion  121  of the upper housing  120  and the lower housing  110 . The second waterproof layer  165  may contact an outer surface of the sidewall  125 . The first waterproof layer  161  may include, for example, rubber. As the lower housing  110  is coupled to the upper housing  120 , the lower housing  110  and the upper housing  120  may apply a certain pressure to the second waterproof layer  165 . Accordingly, the second waterproof layer  165  may secure the isolation of the substrate  130  and the LED package  140  from a sterilization-target fluid such as water or the like. 
     The molding layer  180  may be provided onto the lower surface of the substrate  130 . The molding layer  180  may include epoxy, silicone, and the like. 
     The connector  190  may be connected to the substrate  130 . The connector  190  may be electrically connected to the LED package  140  via the substrate  130 . As a non-limiting example, the substrate  130  may be a double-side wiring substrate and may be electrically connected to each of the LED package  140  arranged on the upper surface thereof and the connector  190  arranged on the lower surface thereof. 
       FIG.  5    is a diagram illustrating a water supplier  10  according to example embodiments. 
     Referring to  FIGS.  1  and  5   , the water supplier  10  may include a container  20 , which stores a fluid such as water W or the like, and the UV light source  100 . 
     The container  20  may store the water W. The water supplier  10  may be configured to supply the water W stored in the container  20  to the outside thereof. According to example embodiments, the container  20  may include an inner wall  20  W defining an opening for mounting the UV light source  100 . The UV light source  100  coupled to the container  20  may sterilize a fluid such as the water W by irradiating the fluid such as the water W in the container  20  with UV light. 
     According to example embodiments, one or more of the UV light source  100  may be coupled to the inner wall  20 W. According to example embodiments, the lower housing  110  of the UV light source  100  may contact an outer surface  20 E of the container  20 . According to example embodiments, the second waterproof layer  165  of the UV light source  100  may contact an inner surface  20 I of the container  20 . According to example embodiments, when the UV light source  100  is installed to the container  20 , the second waterproof layer  165  may be arranged between the inner surface  201  of the container  20  and the lower surface of the upper housing  120 . According to example embodiments, the second waterproof layer  165  may be pressed by the inner surface  201  of the container  20  and the lower surface of the upper housing  120 . Accordingly, the second waterproof layer  165  may prevent a fluid such as the water W from reaching the substrate  130  and the LED package  140  through a space between the inner surface  201  of the container  20  and the lower surface of the upper housing  120 . The first waterproof layer  161  may prevent a fluid such as the water W from reaching the substrate  130  and the LED package  140  through a space between the lower surface of the upper housing  120  and the waterproof coating layer  150 . 
     One or more of the UV light source  100  may be provided in the container  20 , in which a fluid such as the water W is stored, while being suspended by a wire  191 . 
       FIG.  6    is a diagram illustrating an air supplier  11  according to example embodiments. 
     Referring to  FIGS.  1  and  6   , the air supplier  11  may include a flow path  21 , which stores a fluid such as air, and the UV light source  100 . 
     The flow path  21  may provide a path for air AR to move according to an operation of the air supplier  11 . There may be water vapor included in the air AR, and dew D caused by condensation of water vapor, inside the flow path  21 . According to example embodiments, the UV light source  100  may be coupled to the flow path  21 . According to example embodiments, the flow path  21  may include an inner wall  21 W defining an opening for mounting the UV light source  100 . The UV light source  100  may sterilize a fluid (e.g., the the air AR) by irradiating the fluid in the flow path  21  with UV light. 
     According to example embodiments, the UV light source  100  may be coupled to the inner wall  21 W of the flow path  21 . According to example embodiments, the lower housing  110  of the UV light source  100  may contact an outer surface  21 E of the flow path  21 . According to example embodiments, the second waterproof layer  165  of the UV light source  100  may contact an inner surface  21 I of the flow path  21 . According to example embodiments, when the UV light source  100  is mounted to the flow path  21 , the second waterproof layer  165  may be arranged between the inner surface  211  of the flow path  21  and the lower surface of the upper housing  120 . According to example embodiments, the second waterproof layer  165  may be pressed by the inner surface  211  of the flow path  21  and the lower surface of the upper housing  120 . Accordingly, the second waterproof layer  165  may prevent a fluid such as the dew D and the air AR from reaching the LED package  140  and the substrate  130  through a space between the inner surface  211  of the flow path  21  and the lower surface of the upper housing  120 . The first waterproof layer  161  may prevent a fluid such as the air AR from reaching the substrate  130  and the LED package  140  through a space between the lower surface of the upper housing  120  and the waterproof coating layer  150 . 
       FIG.  7 A  is a partial cross-sectional view illustrating a portion of a UV light source according to other example embodiments and illustrates a portion corresponding to  FIG.  3   . 
     Because components shown in  FIG.  7 A , except for a waterproof coating layer  151 , are substantially the same as described with reference to  FIG.  3   , repeated descriptions thereof are omitted. 
     Referring to  FIG.  7 A , the waterproof coating layer  151  may include a first portion  151 P 1 , which covers the upper surface of the substrate  130 , and a second portion  151 P 2 , which covers the lateral surface  141 S and the lateral surface  147 S of the LED package  140 . As a non-limiting example, the first portion  151 P 1  may have a conformal shape. The first portion  151 P 1  may have a constant thickness. 
     In the present example, a dynamic viscosity of a coating material for forming the waterproof coating layer  151  may range from about 5000 cps to about 10000 cps. The waterproof coating layer  151  may be provided by a dispensing process, a spraying process, an ink-jet process, and the like of a coating material including silicone, epoxy, and the like. The second portion  151 P 2  of the waterproof coating layer  151  may include an inclined plane. 
       FIG.  7 B  is a partial cross-sectional view illustrating a portion of a UV light source according to other example embodiments and illustrates a portion corresponding to  FIG.  3   . 
     Because components shown in  FIG.  7 B , except for a waterproof coating layer  152 , are substantially the same as described with reference to  FIG.  3   , repeated descriptions thereof are omitted. 
     Referring to  FIG.  7 B , the waterproof coating layer  152  may include a first portion  152 P 1 , which covers the upper surface of the substrate  130 , and a second portion  152 P 2 , which covers the lateral surface  141 S and the lateral surface  147 S of the LED package  140 . As a non-limiting example, the first portion  152 P 1  may have a conformal shape. The first portion  152 P 1  may have a constant thickness. 
     In the present example, the waterproof coating layer  152  may be provided by a dispensing process, a spraying process, an ink-jet process, and the like of a low-viscosity coating material. In the present example, a dynamic viscosity of a coating material for forming the waterproof coating layer  152  may range from about 1 cps to about 5000 cps. Accordingly, the second portion  152 P 2  of the waterproof coating layer  152  may have a concave shape. The waterproof coating layer  152  may include silicone, epoxy, and the like. 
       FIG.  7 C  is a partial cross-sectional view illustrating a portion of a UV light source according to other example embodiments and illustrates a portion corresponding to  FIG.  3   . 
     Because components shown in  FIG.  7 C , except for a waterproof coating layer  153 , are substantially the same as described with reference to  FIG.  3   , repeated descriptions thereof are omitted. 
     Referring to  FIG.  7 C , the waterproof coating layer  153  may include silicone, epoxy, and the like. The waterproof coating layer  153  may include a first portion  153 P 1 , which covers the upper surface of the substrate  130 , and a second portion  153 P 2 , which covers the lateral surface  141 S and the lateral surface  147 S of the LED package  140 . As a non-limiting example, the first portion  153 P 1  may have a conformal shape. The first portion  153 P 1  may have a constant thickness. 
     As a non-limiting example, the second portion  153 P 2  of the waterproof coating layer  153  may partially cover the upper surface  147 U of the transparent layer  147 . According to example embodiments, the second portion  153 P 2  of the waterproof coating layer  153  may cover an edge portion of the upper surface  147 U of the transparent layer  147 . According to example embodiments, the second portion  153 P 2  of the waterproof coating layer  153  may contact the edge portion of the upper surface  147 U of the transparent layer  147 . According to example embodiments, the waterproof coating layer  153  may expose a central portion of the upper surface  147 U of the transparent layer  147 . According to example embodiments, the waterproof coating layer  153  may be apart from the central portion of the upper surface  147 U of the transparent layer  147 . 
     According to example embodiments, a portion of the waterproof coating layer  153 , which contacts the upper surface  147 U of the transparent layer  147 , may overlap the dam portion  141 D of the base layer  141  in a vertical direction (for example, a direction that is perpendicular to the upper surface of the substrate  130 ). According to example embodiments, the portion of the waterproof coating layer  153 , which contacts the upper surface  147 U of the transparent layer  147 , may be apart from an optical path of a luminous flux generated by the LED chip  145 . According to example embodiments, the portion of the waterproof coating layer  153 , which contacts the upper surface  147 U of the transparent layer  147 , may be farther from the LED chip  145  in a horizontal direction (for example, a direction that is parallel to the upper surface of the substrate  130 ) than a distance from the LED chip  145  to an inner surface  141 DI of the dam portion  141 D of the base layer  141  in the horizontal direction. Accordingly, even though the portion of the waterproof coating layer  153  is arranged on the upper surface  147 U of the transparent layer  147 , the deterioration of light extraction efficiency of the UV light source may be prevented. 
       FIG.  7 D  is a partial cross-sectional view illustrating a portion of a UV light source according to other example embodiments and illustrates a portion corresponding to  FIG.  3   . 
     Because components shown in  FIG.  7 D , except for a waterproof coating layer  154 , are substantially the same as described with reference to  FIG.  3   , repeated descriptions thereof are omitted. 
     Referring to  FIG.  7 D , the waterproof coating layer  154  may include silicone, epoxy, and the like. The waterproof coating layer  154  may include a first portion  154 P 1 , which covers the upper surface of the substrate  130 , and a second portion  154 P 2 , which covers the lateral surface  141 S and the lateral surface  147 S of the LED package  140 . As a non-limiting example, the first portion  154 P 1  may have a conformal shape. The first portion  154 P 1  may have a constant thickness. 
     As a non-limiting example, the second portion  154 P 2  of the waterproof coating layer  154  may not cover the upper surface  147 U of the transparent layer  147 . According to example embodiments, the second portion  154 P 2  of the waterproof coating layer  154  may cover a portion of the lateral surface  147 S of the transparent layer  147 . According to example embodiments, the second portion  154 P 2  of the waterproof coating layer  154  may cover a lower portion of the lateral surface  147 S of the transparent layer  147  and may not cover an upper portion of the lateral surface  147 S of the transparent layer  147 . According to example embodiments, the second portion  154 P 2  of the waterproof coating layer  154  may contact the lower portion of the lateral surface  147 S of the transparent layer  147  and may be apart from the upper portion of the lateral surface  147 S of the transparent layer  147 . According to example embodiments, the second portion  154 P 2  of the waterproof coating layer  154  covers a bonding portion between the base layer  141  and the transparent layer  147 , and thus, waterproofing of the LED package  140  against a sterilization-target fluid may be secured. 
       FIG.  7 E  is a partial cross-sectional view illustrating a portion of a UV light source according to other example embodiments and illustrates a portion corresponding to  FIG.  3   . 
     Because components shown in  FIG.  7 E , except for a waterproof coating layer  155 , are substantially the same as described with reference to  FIG.  3   , repeated descriptions 
     Referring to  FIG.  7 E , the waterproof coating layer  155  may include silicone, epoxy, and the like. The waterproof coating layer  155  may include a first portion  155 P 1 , which covers the upper surface of the substrate  130 , and a second portion  155 P 2 , which covers the lateral surface  141 S of the LED package  140 . As a non-limiting example, the first portion  155 P 1  may have a conformal shape. The first portion  155 P 1  may have a constant thickness. 
     As a non-limiting example, the second portion  155 P 2  of the waterproof coating layer  155  may not cover the upper surface  147 U and the lateral surface  147 S of the transparent layer  147 . According to example embodiments, the second portion  155 P 2  of the waterproof coating layer  155  may be apart from the transparent layer  147 . According to example embodiments, the waterproof coating layer  155  may partially cover the lateral surface  141 S of the base layer  141 . According to example embodiments, the waterproof coating layer  155  may cover a lower portion of the lateral surface  141 S of the base layer  141  and may not cover an upper portion of the lateral surface  141 S of the base layer  141 . According to example embodiments, the waterproof coating layer  155  may contact the lower portion of the lateral surface  141 S of the base layer  141  and may be apart from the upper portion of the lateral surface  141 S of the base layer  141 . According to example embodiments, because the base layer  141  is bonded to the transparent layer  147  by a hermetic seal, even when the waterproof coating layer  155  does not cover a border between the base layer  141  and the transparent layer  147 , the LED package  140  may provide waterproofing of the LED chip  145 . 
       FIG.  7 F  is a partial cross-sectional view illustrating a portion of a UV light source according to other example embodiments and illustrates a portion corresponding to 
     Because components shown in  FIG.  7 F , except for a waterproof coating layer  156 , are substantially the same as described with reference to  FIG.  3   , repeated descriptions thereof are omitted. 
     Referring to  FIG.  7 F , the waterproof coating layer  156  may include silicone, epoxy, and the like. The waterproof coating layer  156  may cover the upper surface of the substrate  130 . According to example embodiments, the waterproof coating layer  156  may have a conformal shape. According to example embodiments, the waterproof coating layer  156  may have a constant thickness. According to example embodiments, the waterproof coating layer  156  may not cover the lateral surface  141 S and the lateral surface  147 S of the LED package  140 . According to example embodiments, the waterproof coating layer  156  may be apart from the lateral surface  141 S and the lateral surface  147 S of the LED package  140 . 
       FIG.  8 A  is a cross-sectional view illustrating a UV light source  101  according to other example embodiments. 
     Referring to  FIG.  8 A , the UV light source  101  may include the lower housing  110 , an upper housing  120 ′, the substrate  130 , the LED package  140 , the waterproof coating layer  150 , the first waterproof layer  161 , the second waterproof layer  165 , a securing device  171 , the molding layer  180 , and the connector  190 . 
     Because the lower housing  110 , the substrate  130 , the LED package  140 , the waterproof coating layer  150 , the first waterproof layer  161 , the second waterproof layer  165 , the molding layer  180 , and the connector  190  are substantially the same as described with reference to  FIGS.  1  to  3   , repeated descriptions thereof are omitted. 
     The upper housing  120 ′ is substantially similar to the upper housing  120  of  FIG.  1    except for a groove  125 G formed in the sidewall  125 ′. 
     According to example embodiments, a securing device  171  may be coupled to the groove  125 G of the upper housing  120 ′ and thus secure the substrate  130  and the first waterproof layer  161 . According to example embodiments, the securing device  171  may have a ring shape and may include a protrusion  171 P for being coupled to the groove  125 G in an interference fit manner. 
       FIG.  8 B  is a cross-sectional view illustrating a UV light source  102  according to other example embodiments. 
     Referring to  FIG.  8 B , the UV light source  102  may include the lower housing  110 , an upper housing  120 ″, a substrate base  131 , the LED package  140 , the waterproof coating layer  150 , the first waterproof layer  161 , the second waterproof layer  165 , the molding layer  180 , and the connector  190 . 
     Because the lower housing  110 , the LED package  140 , the waterproof coating layer  150 , the first waterproof layer  161 , the second waterproof layer  165 , the molding layer  180 , and the connector  190  are substantially the same as described with reference to  FIGS.  1  to  3   , repeated descriptions thereof are omitted. 
     As a non-limiting example, the substrate base  131  may be a single-side PCB. The substrate base  131  may include a circuit pattern formed only on an upper surface thereof, which faces the LED package  140 . Each of the LED package  140  and the connector  190  may be arranged on the upper surface of the substrate base  131 . The connector  190  may be connected to the LED package  140  via the circuit pattern formed on the upper surface of the substrate base  131 . 
     According to example embodiments, the upper housing  120 ″ may include a plate portion  121 ′ and the sidewall  125 . 
     According to example embodiments, the plate portion  121 ′ is similar to the plate portion  121  of  FIG.  1    but may include a recess  121  R for accommodating the connector  190 . 
       FIG.  8 C  is a cross-sectional view illustrating a UV light source  103  according to other example embodiments. 
     Referring to  FIG.  8 C , the UV light source  103  may include the lower housing  110 , the upper housing  120 , the substrate  130 , the LED package  140 , a waterproof coating layer  157 , the first waterproof layer  161 , the second waterproof layer  165 , the molding layer  180 , and the connector  190 . 
     Because the lower housing  110 , the substrate  130 , the LED package  140 , the first waterproof layer  161 , the second waterproof layer  165 , the molding layer  180 , and the connector  190  are substantially the same as described with reference to  FIGS.  1  to  3   , repeated descriptions thereof are omitted. 
     The waterproof coating layer  157  may include silicone, epoxy, and the like. According to example embodiments, the waterproof coating layer  157  may cover a portion of the upper surface of the substrate  130 . According to example embodiments, the waterproof coating layer  157  may cover a central portion of the upper surface of the substrate  130  and may not cover an edge portion of the upper surface of the substrate  130 . 
     According to example embodiments, the waterproof coating layer  157  may not be arranged between the plate portion  121  of the upper housing  120  and the upper surface of the substrate  130 . According to example embodiments, only the first waterproof layer  161  may be arranged between the plate portion  121  of the upper housing  120  and the upper surface of the substrate  130 . According to example embodiments, the upper surface of the first waterproof layer  161  may contact the plate portion  121  of the upper housing  120 , and the lower surface of the first waterproof layer  161  may contact the substrate  130 . 
     According to example embodiments, the waterproof coating layer  157  may not contact the lower surface of the first waterproof layer  161 . According to example embodiments, the waterproof coating layer  157  may be apart from the lower surface of the first waterproof layer  161 . 
     According to example embodiments, the waterproof coating layer  157  may cover only a portion of the upper surface of the substrate  130 , the portion being exposed by the opening  121 O of the upper housing  120 . According to example embodiments, the upper surface of the substrate  130  may be covered by the waterproof coating layer  157  and the first waterproof layer  161 . According to example embodiments, the upper surface of the substrate  130  may be covered by one of the waterproof coating layer  157  and the first waterproof layer  161 . According to example embodiments, a portion of the upper surface of the substrate  130  may be covered by the waterproof coating layer  157 , and another portion of the upper surface of the substrate  130  may be covered by the first waterproof layer  161 . 
     According to example embodiments, the waterproof coating layer  157  is provided onto only the portion of the upper surface of the substrate  130 , which is not covered by the first waterproof layer  161 , and thus, the productivity of the UV light source  103  may be improved. 
       FIG.  8 D  is a cross-sectional view illustrating a UV light source  104  according to other example embodiments. 
     Referring to  FIG.  8 D , the UV light source  104  may include the lower housing  110 , the upper housing  120 , the substrate  130 , the LED package  140 , a waterproof coating layer  158 , the first waterproof layer  161 , the second waterproof layer  165 , the molding layer  180 , and the connector  190 . 
     Because the lower housing  110 , the substrate  130 , the LED package  140 , the first waterproof layer  161 , the second waterproof layer  165 , the molding layer  180 , and the connector  190  are substantially the same as described with reference to  FIGS.  1  to  3   , repeated descriptions thereof are omitted. 
     The waterproof coating layer  158  may include silicone, epoxy, and the like. According to example embodiments, the waterproof coating layer  158  may cover the upper surface, a lateral surface, and the lower surface of the substrate  130 . According to example embodiments, the waterproof coating layer  158  may coat the entire substrate  130 . 
     Accordingly, the waterproof coating layer  158  may include a portion arranged between the first waterproof layer  161  and the substrate  130 , a portion arranged between the sidewall  125  of the upper housing  120  and the substrate  130 , and a portion arranged between the substrate  130  and the molding layer  180 . 
     According to example embodiments, the waterproof coating layer  158  covers the entire substrate  130 , and thus, the waterproofing performance of the UV light source  104  may be further improved. 
       FIG.  9    is a cross-sectional view illustrating a UV light source  105  according to example embodiments. 
       FIG.  10    is a partially enlarged cross-sectional view of a region BB of  FIG.  9   . 
     Referring to  FIGS.  9  and  10   , the UV light source  105  may include the lower housing  110 , the upper housing  120 , the substrate  130 , the LED chip  145 , a waterproof coating layer  159 , the first waterproof layer  161 , the second waterproof layer  165 , the molding layer  180 , and the connector  190 . 
     Because the lower housing  110 , the substrate  130 , the first waterproof layer  161 , the second waterproof layer  165 , the molding layer  180 , and the connector  190  are substantially the same as described with reference to  FIGS.  1  to  3   , repeated descriptions thereof are omitted. 
     The LED chip  145  may be mounted directly on the substrate  130 . The LED chip  145  may have a thickness of about 100 nm to about 700 nm. As a non-limiting example, the LED chip  145  may be coupled to the pads  133  via the solders  146 . The LED chip  145  may be coupled to the pads  133  by eutectic bonding and the solders  146  may be omitted. 
     The waterproof coating layer  159  may include silicone, epoxy, and the like. The waterproof coating layer  159  may include a first portion  159 P 1 , which covers the upper surface of the substrate  130 , and a second portion  159 P 2 , which covers the lateral surface of the LED chip  145 . The first portion  159 P 1  of the waterproof coating layer  159  may contact the upper surface of the substrate  130 . The second portion  159 P 2  of the waterproof coating layer  159  may contact the lateral surface of the LED chip  145 . According to example embodiments, the waterproof coating layer  159  may further cover the solders  146 . 
     According to example embodiments, the LED chip  145  is mounted directly on the substrate  130 , and thus, light having passed through the transparent layer  1451  (see  FIG.  4   ) of the LED chip  145  may be directly transferred to a sterilization-target fluid such as water without passing through a transparent layer (e.g., a transparent layer  147  of  FIG.  3   ) of an LED package. In addition, the cost and time required for packaging the LED chip  145  may be reduced, and thus, the productivity of the UV light source  105  may be improved. 
     Those of ordinary skill in the art would also recognize, based on the descriptions made herein, that the present disclosure also includes an embodiment where the waterproof coating layer  159  includes only the first portion  159 P 1  covering the upper surface of the substrate  130 , an embodiment where the second portion  159 P 2  of the waterproof coating layer  159  has a straight slope, and an embodiment where the second portion  159 P 2  of the waterproof coating layer  159  has a concave shape. 
       FIG.  11    is a flowchart illustrating a method of manufacturing a UV light source, according to example embodiments. 
       FIGS.  12 A to  12 C  are diagrams illustrating a method of manufacturing a UV light source, according to example embodiments. 
     Referring to  FIGS.  11  and  12 A , in P 10 , the LED package  140  may be mounted on the substrate  130 . According to example embodiments, passive elements such as a resistor and a capacitor may be further mounted on the substrate  130 . The LED package  140  and the additional passive elements may be coupled to the substrate  130  by a surface mounting technique. According to example embodiments, the connector  190  including the wire  191  may be connected to the substrate  130 . 
     Next, referring to  FIGS.  11  and  12 B , in P 20 , the waterproof coating layer  150  may be provided. Providing the waterproof coating layer  150  may include providing a coating material including silicone, epoxy, and the like by a dispensing and spraying process, and curing the coating material. The coating material may be cured by one of UV curing and thermal curing. The waterproof coating layer  150  may cover the upper surface of the substrate  130  and the lateral surface of the LED package  140 . 
     Next, referring to  FIGS.  11  and  12 C , in P 30 , the substrate  130  on which the LED package  140  is mounted may be coupled to the upper housing  120 . When the substrate  130  is coupled to the upper housing  120 , the first waterproof layer  161  may be arranged therebetween. The substrate  130  may be secured to the upper housing  120  by at least one of the securing devices  170  (see  FIG.  2   ). The substrate  130  may be secured to the upper housing  120  while being located to press the first waterproof layer  161 . 
     Next, referring to  FIGS.  11  and  1   , in P 40 , the molding layer  180  may be provided under the substrate  130 , and the upper housing  120  may be coupled to the lower housing  110 . When the upper housing  120  is coupled to the lower housing  110 , the second waterproof layer  165  may be arranged therebetween. The upper housing  120  and the lower housing  110  may be secured to each other while being located to press the second waterproof layer  165 . 
     While non-limiting example embodiments of the present disclosure have been particularly shown and described, it will be understood that various changes in form and details may be made to embodiments of the present disclosure without departing from the spirit and scope of the present disclosure.