Abstract:
A method of manufacturing a printed circuit board (PCB) and the PCB are provided. The method includes: filling a resin in a via-hole formed at a substrate from one surface side of the substrate; emitting light for a predetermined period of time to the resin filled in the via-hole from the other surface side of the substrate; and applying another resin on the other surface of the substrate.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
     This application claims priority from Korean Patent Application No. 10-2012-0054452, filed on May 22, 2012, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
     BACKGROUND 
     1. Field 
     Apparatuses and methods consistent with exemplary embodiments relate to a printed circuit board (PCB), and more particularly, to a PCB and a method of manufacturing the same. 
     2. Description of the Related Art 
     In order to manufacture a semiconductor package, a substrate on which a semiconductor chip including electrical circuits is to be mounted is required. The substrate has a circuit pattern on one surface or both surfaces thereof to transmit an electrical signal from the semiconductor chip to an external device or to receive an electrical signal from an external device. In order to electrically connect the circuit patterns formed on both surfaces of the substrate, a plurality of via-holes are formed in the substrate and are plated. Empty spaces of the via-holes after the plating are filled with a resin. 
     The resin filled in the via-holes is cured. The resin is recessed while being cured. Once the resin filled in the via-holes is recessed, when the semiconductor chip is mounted on the substrate, an adhesive force between the semiconductor chip and the substrate is reduced. In order to prevent the resin filled in the via-holes from being recessed, a method of flattening the resin has been developed. 
     A method of flattening a resin filled in via-holes is disclosed in Japanese Patent Application Publication No. hei 11-340626 (hereinafter, referred to as a reference). The reference discloses a method of filling a resin in via-holes and applying ultraviolet light to an entire surface of a substrate. As such, once the ultraviolet light is applied to the entire surface of the substrate, the ultraviolet light may affect a circuit pattern formed on the substrate, thereby reducing the conductivity of the circuit pattern. 
     SUMMARY 
     One or more exemplary embodiments provide a PCB that flattens a resin filled in a via-hole and a method of manufacturing the PCB. 
     According to an aspect of an exemplary embodiment, there is provided a method of manufacturing a PCB, the method including: filling a resin in a via-hole formed at a substrate from one surface side of the substrate; emitting light for a predetermined period of time to the resin filled in the via-hole from the other surface side of the substrate; and applying another resin on the other surface of the substrate. 
     To emit the light, there may be provided a mask which is patterned such that the light is blocked from being emitted to the area where the via-hole is not formed and the light is applied to the via-hole. The mask may be disposed over the other surface of the substrate, and the light can be emitted to the mask. 
     The other resin may be applied on the other surface of the substrate two times. 
     The applying the other resin two times may include: applying resin on the other surface of the substrate a first time; curing the substrate a first time; applying resin on the other surface of the substrate a second time; and curing the substrate a second time. 
     According to an aspect of another exemplary embodiment, there is provided a method of manufacturing a PCB, the method including: filling a resin in a via-hole formed at a substrate from one surface side of the substrate; applying hot air for a predetermined period of time to the resin filled in the via-hole from the other surface side of the substrate; and applying another resin on the other surface of the substrate. 
     To apply the hot air, there may be provided a mask which is patterned such that the hot air is blocked from being applied to the area where the via-hole is not formed and the hot air is applied to the via-hole. The mask may be disposed over the other surface of the substrate, and the hot air is applied to the mask. 
     The other resin may be applied on the other surface two times. 
     The applying the other resin two times may include: applying resin on the other surface of the substrate a first time; curing the substrate a first time; applying resin on the other surface of the substrate a second time; and curing the substrate a second time. 
     After the patterning at least one surface of the substrate, the method may further include curing the substrate. 
     According to an aspect of another exemplary embodiment, there is provided a PCB manufactured by using one of the above methods. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which: 
         FIG. 1  is a flowchart illustrating a method of manufacturing a PCB according to an exemplary embodiment; 
         FIGS. 2A through 2D  are cross-sectional views illustrating an operation of filling a via-hole in the method of  FIG. 1  according to an exemplary embodiment; 
         FIG. 3A  is a cross-sectional view illustrating a state where a resin is coated on a surface of the substrate according to an exemplary embodiment; 
         FIG. 3B  is a cross-sectional view illustrating a state where the substrate of  FIG. 3A  is cured according to an exemplary embodiment; 
         FIG. 4  is a cross-sectional view for explaining a method of coating a liquid resin on the substrate by using screen printing according to an exemplary embodiment; 
         FIGS. 5A and 5B  are cross-sectional views for explaining a method of coating a liquid resin on the substrate by using roll coating according to an exemplary embodiment; 
         FIG. 6  is a cross-sectional view for explaining a method of applying light to the substrate according to an exemplary embodiment; 
         FIG. 7  is a cross-sectional view illustrating a result obtained by applying light to the substrate by using the method of  FIG. 6  exemplary embodiments; 
         FIG. 8  is a cross-sectional view illustrating a state where a resin is coated on the other surface of the substrate according to an exemplary embodiment; 
         FIGS. 9A through 9D  are cross-sectional views for explaining a method of coating a resin on the other surface of the substrate two times according to an exemplary embodiment; 
         FIG. 10  is a cross-sectional view illustrating the PCB manufactured by using the method according to an exemplary embodiment; 
         FIG. 11  is a flowchart illustrating a method of manufacturing the PCB according to another exemplary embodiment; 
         FIG. 12  is a cross-sectional view for explaining a method of applying hot air to a substrate according to an exemplary embodiment; 
         FIG. 13A  is a cross-sectional view illustrating a substrate when a resin filled in a via-hole is flattened in a conventional method; and 
         FIG. 13B  is a cross-sectional view illustrating a substrate when a resin filled in a via-hole is flattened in a method according to exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The inventive concept will become more apparent to one of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same members. 
       FIG. 1  is a flowchart illustrating a method of manufacturing a PCB  202 , according to an exemplary embodiment. Referring to  FIGS. 1-3B , the method includes operations  111  through  131 . 
     In operation  111 , a via-hole  221  formed at a substrate  210  is filled in by a resin  241 . The via-hole  221  may be filled in by coating the resin  241 . 
     A plurality of the via-holes  221  may be formed at the substrate  210 . For convenience, the following description will be made on the assumption that one via-hole  221  is formed at the substrate  210 . 
     In order to form the via-hole  221  at the substrate  210 , the following four processes may be performed. 
     In a first process, referring to  FIG. 2A , the substrate  210 , including a core substrate  201  and copper layers  211  and  212  formed on both surfaces of the core substrate  201 , is prepared. The copper layers  211  and  212  may be replaced with metal layers each having conductivity. The core substrate  201  may be formed of one or a combination of insulating materials such as glass cloth, epoxy resin, polyimide, polymer, liquid crystal polymer, polytetrafluoroethylene (PTFE), poly(methyl methacrylate), and polycarbonate. The core substrate  201  has a flat shape. The core substrate  201  may be formed of a rigid material or a flexible material. 
     Adhesive layers (not shown) may be formed between the copper layer  211  and the core substrate  201  and/or between the copper layer  212  and the core substrate  201 . Due to the adhesive layers, the copper layers  211  and  212  are attached to the core substrate  201 . The copper layers  211  and  212  may be formed by stacking copper plates having the same size as that of the core substrate  201  on the adhesive layers or by depositing a copper material on the core substrate  201  by using vacuum deposition. Examples of the vacuum deposition may include sputtering, thermal evaporation, and e-beam deposition. 
     Since the copper layers  211  and  212  are used as media through which current flows when electroplating is performed, it is preferable, but not necessary, that the copper layers  211  and  212  are thin to reduce costs. To this end, thin copper layers may be stacked on both surfaces of the core substrate  201  or the copper layers  211  and  212  staked on the core substrate  201  may be polished to be thin. 
     In a second process, referring to  FIG. 2B , the via-hole  221 , which vertically passes through the substrate  210 , is formed. The vial-hole  221  may be formed by using a drill or by using a laser beam. 
     In a third process, referring to  FIG. 2C , a first copper plating layer  231  is formed on an inner wall of the via-hole  221  by using electroless plating. The first copper plating layer  231  is formed to have a thickness less than that of each of the copper layers  211  and  212 . 
     In a fourth process, referring to  FIG. 2D , a second copper plating layer  232  is formed on a surface of the first copper plating layer  231  by using electroplating. Due to the first and second copper plating layers  231  and  232 , the copper layer  211  formed on a bottom surface of the substrate  210  and the copper layer  212  formed on a top surface of the substrate  2140  are electrically connected to each other. That is, as a thickness of a copper plating layer formed on the inner wall of the via-hole  221  is increased due to the second copper plating layer  232 , the copper layer  211  formed on the bottom surface of the substrate  210  and the copper layer  212  formed on the top surface of the substrate  210  are stably electrically connected to each other. 
     Next, a process of cleaning surfaces of the copper layers  211  and  212  may be performed. In order to clean the surfaces of the copper layers  211  and  212 , wet cleaning or plasma processing may be performed. In order to perform the plasma processing, plasma is forced to collide with the surfaces of the copper layers  211  and  212 . Accordingly, surface energy of the copper layers  211  and  212  is increased. Accordingly, when resins  241  and  251  are formed as photoresist layers (see  FIG. 8 ) on the copper layer  212 , an adhesive force between the photoresist layers and the copper layers  211  and  212  is increased, and, thus defects do not occur when patterns of the photoresist layers are formed. 
     Referring to  FIG. 3A , the via-hole  221  (see  FIG. 2D ) is filled in by coating the resin  241  on a surface of the substrate  2140 , for example, the bottom surface of the substrate  210 . As the via-hole  221  is filled with the resin  241 , voids are not formed at the via-hole  241 . The resin  241  coated on the bottom surface of the substrate  210  may include a photo solder resist (the resin  241  is on the inner walls of the via-hole  241  and edge surfaces of the copper layers  211  and/or  212   
     After the resin  241  is coated on the bottom surface of the substrate  210 , the substrate  210  is cured. Once the substrate  210  is cured, the resin  241  filled in the via-hole  210  is recessed to have a recessed portion  246 , as shown in  FIG. 3B . 
     In order to cure the substrate  210 , infrared curing or oven curing may be performed. The infrared curing, which involves curing the substrate  210  by using infrared light, may be performed by preheating the substrate  210  for 1 minute, heating the substrate  210  at 60° C. for 3 minutes, heating the substrate  210  at 70° C. for 3 minutes, heating the substrate  210  at 80° C. for 3 minutes, and cooling the substrate  210  for 1 minute. When the infrared curing is performed, since curing occurs from an inner surface of the resin  241  contacting the substrate  210 , an adhesive force of the resin  241  is increased. The oven curing cures the resin  241  coated on the substrate  210  by putting the substrate  210  into an oven (not shown) which is heated to a predetermined temperature, for example, 300 to 400° C., and heating the substrate  210  for a predetermined period of time. The temperature and the time are exemplary and are not limited, and may vary according to a type of the substrate  210  or a type of equipment. 
     In order to coat the resin  241  on a surface of the substrate  210 , screen printing and roll coating may be used. If a resin to be coated on the substrate  210  is liquid, the screen printing or the roll coating may be used. 
     In the screen printing, referring to  FIG. 4 , a screen mask  401  is disposed over the substrate  210 , and a liquid resin is transferred from the screen mask  401  to the substrate  210 . In this case, the liquid resin is cured by applying heat to the liquid resin. The screen mask  401  includes a screen mesh  411 , a tension mesh  421 , and a fixed frame  431 . The screen mesh  411 , which is a print effect area, has a plurality of holes  413  formed therein. The screen mesh  411  overlaps with the top surface of the substrate  210 , and the liquid resin is transferred to the top surface of the substrate  210  through the screen mesh  411 . The tension mesh  421  enables the screen mesh  411  to be maintained at a constant tensile force. The fixed frame  431  is used to fix the tension mesh  421 . 
     In the roll coating, referring to  FIG. 5A , when the substrate  210  wound on a supply roller  511  is unfastened, and then, wound on a reception roller  512 , a liquid resin  525  may be coated on a surface of the substrate  210  by passing the substrate  210  through a container  521  in which the liquid resin  525  is contained. A thickness of the liquid resin  525  coated on the substrate  210  may be adjusted by adjusting a time and a speed at which the substrate  210  passes through the liquid resin  525 . In order to cure the liquid resin  525  coated on the surface of the substrate  210 , heat may be applied to the substrate  210 . 
     In another example of the roll coating, referring to  FIG. 5B , when the substrate  210  wound on the supply roller  511  is unfastened, and then, wound on the reception roller  512 , the liquid resin  525  may be coated on the surface of the substrate  210  by ejecting the liquid resin  525  to the substrate  210  through a nozzle  523 . A thickness of the liquid resin  525  coated on the substrate  210  may be adjusted by adjusting an amount and a force of the liquid resin  525  ejected through the nozzle  523  or a speed at which the substrate  210  is fed. In order to cure the liquid resin  525  coated on the surface of the substrate  210 , heat may be applied to the substrate  210 . 
     In operation  121 , light  613  and  615  (see  FIG. 6 ), for example, ultraviolet light, is emitted for a predetermined period of time to the resin  241  filled in the via-hole  221  on the other surface of the substrate  210 , for example, the top surface of the substrate  210 . When the light  613  and  615  is emitted to the other surface of the substrate  210 , the light  613  is blocked from being emitted to an area where the via-hole  221  is not formed and the light  615  is emitted to the via-hole  221 . That is, a mask  601  that is patterned to block the light  613  from being emitted to the area where the via-hole  221  is not formed and to emit the light  615  to the via-hole  221  is disposed on the top surface of the substrate  210 , and the light  613  and  615  is emitted to the mask  601 . The light  613  and  615  may be ultraviolet light. 
     Referring to  FIG. 6 , the mask  601  is disposed on the substrate  210 , and an ultraviolet light source  611  is disposed on the mask  601 . The mask  601  is formed of a material capable of blocking ultraviolet light. A plurality of holes  605  are formed in the mask  601  in a pattern having the same positions and sizes as a plurality of the via-holes  221  (see  FIG. 2B ) formed at the substrate  210 . Accordingly, the ultraviolet light  613  and  615  emitted by the ultraviolet light source  611  is emitted to only the plurality of via-holes  221  formed at the substrate  210  through the plurality of holes  605  formed at the mask  601 . That is, the mask  601  is manufactured and disposed such that only the via-holes  221  of the substrate  210  are exposed to the ultraviolet light  613  and  615 . 
     The resin  241  filled in each of the via-holes  221  is recessed during the curing. In this state, when the ultraviolet light  615  is emitted to the resin  241  filled in the via-hole  221 , the resin  241  is optically cured and is prevented from being recessed during the curing (see  FIG. 7 ). 
     A speed at which the resin  241  is optically cured varies according to a distance between the mask  601  and the substrate  210 , a time during when the ultraviolet light  615  is emitted to the resin  241  filled in the via-hole  221 , and a force of the ultraviolet light  615 . In this case, it is necessary to set ultraviolet exposure conditions under which the resin  241  filled in the via-hole  221  is sufficiently cured and is prevented from being recessed. 
     A process of disposing the mask  601  over the substrate  210  and exposing the resin  241  filled in the via-hole  221  to the ultraviolet light  615  is simple as described above, and the resin  241  exposed to the ultraviolet light  615  is cured in a short time. That is, a process of flattening the resin  241  filled in the via-hole  221  is simple and takes a short time. 
     In operation  131 , referring to  FIG. 8 , the resin  251  is coated on the top surface of the substrate  210 . The resin  251  may include a photo solder resist. Due to the resin  251  coated on the top surface of the substrate  210 , the recessed portion  246  (see  FIG. 7 ) of the resin  251  filled in the via-hole  221  is filled up. Accordingly, as shown in  FIG. 8 , the resin  251  coated on the top surface of the substrate  210  is flattened. 
     The resin  251  may be coated on the top surface of the substrate  210  only one time or two times. When the resin  251  is coated two times, the flatness of the resin  251  coated on the top surface of the substrate  210  is improved. 
     In order to coat the resin  251  on the top surface of the substrate  210  two times, the following four processes may be performed. 
     In a first process, referring to  FIG. 9A , a resin  261  is coated on the top surface of the substrate  210 . Since the resin  261  is coated on the substrate  210 , the recessed portion  246  (see  FIG. 7 ) of the resin  241  is filled up. In order to coat the resin  261  on the top surface of the substrate  210 , screen printing or roll coating may be used. The screen printing or the roll coating may be performed in the same manner as that described in operation  111 . 
     In a second process, referring to  FIG. 9B , the substrate  210  is cured. When the substrate  210  is cured, the resin  261  coated on the top surface of the substrate  210  is cured. As the resin  261  is cured, a volume of the resin  261  filled in the via-hole  221  is reduced and recessed to have a recessed portion. In this case, a depth of the recessed portion is less than a depth of the recessed portion  246  in operation  111 . In order to cure the substrate  210 , infrared curing or oven curing may be performed. The infrared curing or the oven curing may be performed in the same manner as that described in operation  111 . 
     In a third process, referring to  FIG. 9C , a resin  271  is coated on the top surface of the substrate  210 . That is, the resin  271  is coated on the resin  261  coated on the substrate  210 . Since the resin  271  is coated on the substrate  210 , the recessed portion of the resin  261  filled in the via-hole  221  on the top surface of the substrate  210  is filled up. In order to coat the resin  271 , screen printing or roll coating may be used. The screen printing or the roll coating may be performed in the same manner as that described in operation  111 . 
     In a fourth process, referring to  FIG. 9D , the substrate  210  on which the resin  271  is coated is cured again. When the substrate  210  is cured, the resin  271  coated on the top surface of the substrate  210  is cured. As the resin  271  is cured, a volume of the resin  271  coated on the via-hole  221  is reduced and recessed to have a recessed portion. In this case, a depth of the recessed portion is less than a depth of the recessed portion in the second process. In order to pre-cure the substrate  210 , infrared curing or oven curing may be performed. The infrared curing or the oven curing may be performed in the same manner as that described in operation  111 . 
     As described above, since the resin  251  is coated two times on the top surface of the substrate  210 , the resin  251  coated on the via-hole  221  on the top surface of the substrate  210  is flattened. 
     Referring to  FIG. 10 , the resin  251  is coated on the top surface of the substrate  210  and both surfaces of the substrate  210  are patterned, thereby completing manufacture of the PCB  202 . In order to pattern the both surfaces of the substrate  210 , a photoresist may be coated on the both surfaces of the substrate  210  and then masking, exposure, development, and etching may be performed. Since the both surfaces of the substrate  210  may be patterned by using a general method, a detailed explanation of the general method is not given. According to another exemplary embodiment, only one surface may be patterned to complete manufacture of the PCB  202   
     After the both surfaces of the substrate  210  are patterned, the PCB  202  may be cured again. When the PCB  202  is cured at this time, the resins  241  and  251  coated on the PCB  202  are completely cured. In this case, the resin  241  filled in the via-hole  221  on a surface, that is, the bottom surface, of the PCB  202  is cured and is recessed to a predetermined depth. A semiconductor chip needed to manufacture a semiconductor package is attached to the other surface, that is, the top surface, of the PCB  202 . Thus, even when the resin  241  filled in the via-hole  221  on the surface of the PCB  202  is recessed, the semiconductor package is not affected. In order to cure the PCB  202  after the substrate  210  is patterned, infrared curing or oven curing may be used. The infrared curing or the oven curing may be performed in the same manner as that described in operation  111 . 
       FIG. 11  is a flowchart illustrating a method of manufacturing the PCB  202 , according to another embodiment. Referring to  FIG. 11 , the method includes operations  1111  through  1131 . Operations  1111  and  1131  are the same as operations  111  and  131 , and thus, only operation  1121  will be explained to avoid a repeated explanation. 
     In operation  1121 , hot air is applied for a predetermined period of time to the resin  251  filled in the via-hole  221  on the top surface of the substrate  210  (see  FIG. 12 ). When the hot air is applied to the top surface of the substrate  210 , the hot air is blocked from being applied to an area where the via-hole  221  is not formed and the hot air is applied to the via-hole  221 . A mask  1201 , which is patterned such that the hot air is blocked from being applied to the area where the via-hole  221  is not formed and the hot air is applied to the via-hole  221 , is disposed over the top surface of the substrate  210  (see  FIG. 12 ) and the hot air is applied to the mask  1201 . 
       FIG. 12  is a cross-sectional view for explaining a method of applying hot air to the substrate  210 . Referring to  FIG. 12 , the mask  1201  is disposed on the substrate  210  and a heater  1211  is disposed over the mask  1201 . The mask  1201  is formed of a material capable of blocking hot air  1213 . A plurality of holes  1205  are formed at the mask  1201  in a pattern having the same positions and sizes as a plurality of the via-holes  221  formed at the substrate  210 . Accordingly, hot air  1213  and  1215  emitted from the heater  1211  is applied to only the plurality of via-holes  221  formed at the substrate  210  through the plurality of holes  1205  formed in the mask  1201 . That is, the mask  1201  is manufactured and disposed such that only the via-holes  221  of the substrate  210  are exposed to the hot air  1213  and  1215 . 
     The resin  241  is filled in each of the via-holes  221  of the substrate  210 . As the hot air  1215  is applied to the via-hole  221 , the resin  241  filled in the via-hole  221  is cured and loses its volume. That is, a central portion of the via-hole  221  is maximally recessed as shown in  FIG. 12 . 
     A speed at which the resin  241  filled in the via-hole  221  is cured varies according to a distance between the mask  1201  and the substrate  1201 , a time during when the hot air  1215  is applied to the via-hole  221 , and a force of the hot air  1215 . In this case, it is necessary to set conditions under which the resin  241  filled in the via-hole  221  is sufficiently cured and maximally recessed. 
     Once the resin  241  filled in the via-hole  221  is maximally recessed, the resin  251  filled in the via-hole  221  on the top surface of the substrate  210  may be flattened. 
     A process of disposing the mask  1201  over the substrate  210  and exposing the resin  241  filled in the via-hole  221  to the hot air  1215  is simple as described above and the resin  241  exposed to the hot air  1215  is cured in a short time. That is, a process of flattening the resin  241  filled in the via-hole  221  is simple and takes a short time. 
     After operation  1131  in which the resin  251  is coated on the top surface of the substrate  210 , both surfaces of the substrate  210  may be patterned as shown in  FIG. 10 . In order to pattern the both surfaces of the substrate  210 , a photoresist may be coated on the both surfaces of the substrate  210  and then masking, exposure, development, and etching may be performed. Since the both surfaces of the substrate  210  may be patterned by using a general method, a detailed explanation of the general method is not given. 
     After the both surfaces of the substrate  210  are patterned, the substrate  210  may be cured. When the substrate  210  is cured at this time, the resins  241  and  251  coated on the substrate  210  are completely cured. In this case, the resins  241  filled in the via-hole  221  on the bottom surface, of the substrate  210  is cured and recessed to a predetermined depth. Since a semiconductor chip needed to manufacture a semiconductor package is attached to the top surface of the substrate  210 , even when the resin  241  filled in the via-hole  221  on the bottom surface of the substrate  210  is recessed, the semiconductor package is not affected. In order to cure the substrate  210  at this time, infrared curing or oven curing may be used. The infrared curing or the oven curing may be performed in the same manner as that described in operation  111 . 
       FIGS. 13A and 13B  are cross-sectional views illustrating a PCB  203  and  202  in which a resin  256  is flattened in a conventional method and the PCB  202  in which a resin  255  is flattened in a method according to the above exemplary embodiments. Referring to  FIGS. 13A and 13B , the resin  256  filled in a via-hole on a top surface of the PCB  203  is not completely flattened whereas the resin  255  filled in a via-hole on a top surface of the PCB  202  is completely flattened. 
     According to the exemplary embodiments, when a PCB is manufactured, a resin is filled in a substrate in which a via-hole is formed and ultraviolet light or hot air is applied to only the resin. Accordingly, the resin filled in the substrate is maximally recessed. 
     As described above, when the resin filled in the substrate is maximally recessed, the resin is coated on the substrate and the resin filled in the via-hole is flattened. 
     A process of flattening the resin is simple and takes a short time. Also, since the PCB is manufactured when the resin coated on the via-hole is flattened, a defective rate perceived by customers may be reduced. Also, overall costs for manufacturing the PCB may be reduced. 
     While the inventive concept has been particularly shown and described with reference to exemplary embodiments thereof using specific terms, the embodiments and terms have been used to explain the inventive concept and should not be construed as limiting the scope of the inventive concept defined by the claims. Accordingly, it will be understood by one of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the inventive concept as defined by the following claims.