Abstract:
An LSI package includes an interface module having first and second surfaces and including a wiring board having a first through hole, a driver selectively provided on the second surface, a transmission line connected to the driver, and a first terminal formed on the second surface and connected to the driver, an interposer having a third surface facing the second surface and a fourth surface, and including a signal processor and a second terminal provided on the third surface, a third terminal provided on the fourth surface and a second through hole, the third surface facing the second surface except a region where the driver portion is provided. The interposer is arranged so that the first through hole matches with the second through hole, and a movable guide pin is inserted into the first and second through holes to position the interface module and the interposer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2007-209526, filed Aug. 10, 2007, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    In recent years, it has been demanded that the throughput of an interface connecting LSIs to each other be improved, as an LSI clock frequency increases. To improve the throughput of the interface, the rise of the signal frequency per terminal and the increase of the number of terminals are necessary. However, when the number of the terminals is increased, the area of wiring lines occupied in an LSI package increases, and a wiring length required for the connection tends to increase. On the other hand, when the signal frequency per terminal is raised, the attenuation of an electrical signal per unit length increases, and hence a line length is limited. Therefore, even for a high-speed signal having a high frequency, there is required a contrivance such as the employment of a transmission line or the like in which the attenuation is minimized. 
         [0003]    It is effective to use an optical transmission line as a transmission line which scarcely affects the signal attenuation dependent on the signal frequency. For example, when an optical fiber is used, the signal attenuation due to the transmission through the fiber having a length of about several ten meters can substantially be ignored. When such an optical transmission line is used, it is advantageous to perform electrical/optical signal conversion at a position very close to the LSI. Therefore, there has been investigated a structure in which an optical interface module having a photoelectric conversion function is arranged very close to the LSI package. 
         [0004]    Above all, an LSI package has been proposed in which an interposer (a rewiring substrate) including a signal processing LSI mounted thereon is assembled on a printed wiring board (PWB) by use of a usual mounting step, and then the optical interface module is mounted on the interposer without performing any thermal step later on, whereby the interface module is not thermally influenced (e.g., Jpn. Pat. Appln. KOKAI Publication No. 2004-253456). 
         [0005]    However, in the structure disclosed in the above document, there may be a problem that the positioning of the interface module and the interposer is difficult. For this kind of positioning, there is a method in which reference holes and guide pins are used, but in this method, the guide pins need to be inserted into the plurality of reference holes, respectively. Therefore, clearances are required between the reference holes and the guide pins. This reason is that if the diameter of each guide pin is not smaller than that of the reference hole, the guide pins cannot be inserted into the reference holes, even when a slight deviation (pitch deviation) is produced between the reference holes or between the guide pins. Moreover, the clearances include the pitch deviations and the fluctuations or errors of the hole and pin diameters, and hence they become causes to disturb the highly precise positioning. In consequence, there may be a problem that restrictions are placed on a narrow pitch constitution using a large number of pins for the electrical connection between the interface module and the interposer. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    According to a first aspect of the invention, there is provided an LSI package with an interface module, which includes an interface module having a first surface and a second surface and including a wiring board having a first through hole, a driving element unit selectively provided on the second main surface, a transmission line connected to the driving element unit and configured to transmit and receive a signal, and a first electrical connection terminal formed on the second surface and electrically connected to the driving element unit, an interposer having a third surface facing the second surface and a fourth surface opposite to the third surface, and including a signal processing LSI mounted on the third surface, a second electrical connection terminal provided on the third surface, a mounting board connecting terminal provided on the fourth surface and a second through hole, the interposer being arranged so that the first through hole matches with the second through hole, and a movable guide pin inserted into the first through hole and the second through hole so that the first electrical connection terminal is connected to the second electrical connection terminal, to position the interface module and the interposer, wherein one of the first through hole and the second through hole is a first reference hole, the movable guide pin includes a cylinder portion to be fitted into the other of the first through hole and the second through hole and having a diameter larger than the first reference hole, and a tapered portion including one end to be matched with the cylinder portion and the other end having a diameter smaller than that of the first reference hole, the movable guide pin movable in a direction in which the interposer faces the interface module is provided in a preliminarily fixed state, and the tapered portion of the movable guide pin is pressed to an opening edge of the first reference hole to determine relative positions of the interface module and the interposer in an in-plane direction. 
         [0007]    According to a second aspect of the invention, there is provided an interface module on which a signal processing LSI is mounted and which is to be mounted on an interposer having a plurality of reference holes for positioning, which include a wiring board, a driving element unit provided on a surface of the wiring board which faces the interface module, a transmission line which transmits and receives a signal to and from the driving element unit, an electrical connection terminal formed on the surface and electrically connected to the driving element unit, and a plurality of movable guide pins each having a cylinder portion and a tapered portion connected to the cylinder portion, the diameter of the cylinder portion being larger than a reference hole provided in the interposer, a diameter of an end portion of the tapered portion which faces the interposer being smaller than that of the reference hole, the plurality of movable guide pins being movable in a direction in which the movable guide pins face the interposer and being provided on the wiring board in a preliminarily fixed state, wherein the tapered portions of the movable guide pins are pressed to opening edges of the reference holes of the interposer, whereby the relative position of the interface module is determined with respect to the interposer in the in-plane direction. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0008]      FIGS. 1A and 1B  are sectional views showing the schematic constitution of an LSI package with an interface module according to a first embodiment; 
           [0009]      FIG. 2  is an enlarged sectional view showing the main part constitution of the LSI package with the interface module according to the first embodiment; 
           [0010]      FIGS. 3A-3D  are sectional views for explaining the principle of a height adjustment mechanism in the first embodiment; 
           [0011]      FIGS. 4A and 4B  are sectional views for explaining a mechanism capable of positioning in an in-plane direction according to the first embodiment; 
           [0012]      FIGS. 5A-5D  are sectional views for explaining a comparative example; 
           [0013]      FIGS. 6A and 6B  are plan views showing the arrangement examples of guide pins and reference holes in the first embodiment; 
           [0014]      FIG. 7  is a perspective view showing the mounting way of the package in the first embodiment; 
           [0015]      FIGS. 8A-8D  are sectional views showing a part of an LSI package with an interface module according to a second embodiment; and 
           [0016]      FIG. 9  is a sectional view showing the main part constitution of an LSI package with an interface module according to a third embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    According to the embodiments of the present invention described hereinafter, an interface module and an interposer can highly precisely be positioned, whereby a narrow pitch interconnection using a large number of pins for electrical connection can be achieved. Embodiments of the present invention will hereinafter be described with reference to the drawings. 
       First Embodiment 
       [0018]      FIGS. 1A and 1B  are sectional views showing the schematic constitution of an LSI package with an interface module according to a first embodiment.  FIG. 1A  shows a state before the interface module is connected, and  FIG. 1B  shows a state after the module is connected.  FIG. 2  is an enlarged sectional view showing the main part constitution of the LSI package with the interface module in the state after the interface module is connected. 
         [0019]    In the drawing, a signal processing LSI  1  is mounted on the surface of an interposer  2 . More specifically, the LSI  1  is electrically connected to the interposer  2  via solder bumps (not shown), and solder bump connecting portions are sealed with an underfill resin  3 . 
         [0020]    The surface of the interposer  2  is provided with a high-speed signal wiring line  4 , and a part of this wiring line  4  is connected to a signal input/output terminal of the LSI  1 . Moreover, a part of the high-speed signal wiring line  4  forms a first electrical connection terminal to be connected to a second electrical connection terminal of the interface module described later. 
         [0021]    The back surface of the interposer  2  is provided with mounting board connecting electrical terminals  5  formed of, for example, a ball grid array (BGA) or the like. The interposer  2  is mounted on a mounting board (not shown) by solder reflow using the electrical terminals  5 . Then, a power voltage, a comparatively low-speed control signal and ground potential (GND) are supplied from the mounting board to the LSI  1  through the interposer  2 . 
         [0022]    In the drawing, an interface module  10  has a transmission line  11  for externally distributing a high-speed signal, and a driving element unit  12  which transmits the signal to the transmission line  11  or receives the signal from the transmission line  11 . 
         [0023]    The transmission line  11  is constituted of an optical fiber, an optical wave guide, or a fine coaxial line. In a case where the optical fiber is used as the transmission line  11 , there are many advantages that transmission loss through the optical fiber having a length of several ten meters can substantially be ignored as compared with the fine coaxial line and that the diameter of the fiber can be decreased to realize miniaturization and that ground line can be separated for transmission and reception. 
         [0024]    In the driving element unit  12 , optical devices such as a light emitting device and a light receiving device and an interface IC are embedded. Moreover, a wiring line from the optical device to the interface IC is drawn internally (an LSI  1  side) from an inner wiring line  14 , and is connected to a second electrical connection terminal  16 . The electrical connection terminal  16  is electrically connected to a part (the first electrical connection terminal) of the wiring line  4  formed on the interposer  2 . 
         [0025]    An opening is provided in the center of the interface module  10 . When the interface module  10  is mounted on the interposer  2 , the signal processing LSI  1  is inserted into this opening so that the upper surface of the signal processing LSI  1  has a height substantially equal to that of the upper surface of the interface module  10 . In consequence, the signal processing LSI  1  and the interface module  10  are cooled by a common heat sink  7 . 
         [0026]    The interposer  2  is provided with a circular positioning reference hole  21  extending in a substantially vertical direction with respect to the surface of the interposer  2 . On the other hand, a guide pin  22  having a diameter larger than that of the reference hole  21  is pressed into a holding hole  23 , and is thus preliminarily fixed (semi-fixed) to the interface module  10 . The distal end of the guide pin  22  is tapered, and the pin is thinned toward the distal end thereof. The diameter of the distal end of the pin is smaller than that of the reference hole  21 . The holding hole  23  has a diameter substantially equal to that of the main body (a cylinder portion) of the guide pin  22 , and is extended through the surface of the interface module  10  in a substantially vertical direction. In consequence, the guide pin  22  is movable in a direction in which the interface module  10  faces the interposer  2 . 
         [0027]    It is to be noted that a part of the rear end of the guide pin  22  is pressed into the holding hole  23 , and is preliminarily fixed (semi-fixed) so that the pin does not fall off. Moreover, when a predetermined or more force is applied to the distal end of the guide pin  22 , the guide pin  22  moves backwards. 
         [0028]    To mount the interface module  10  on the interposer  2 , in a state in which the tapered portion of the guide pin  22  is pressed onto the opening edge of the reference hole  21 , the interface module  10  and the interposer  2  are relatively positioned with respect to each other in a lateral direction. At this time, the electrical wiring line  14  of the interface module  10  needs to be securely electrically connected to the electrical wiring line  4  of the interposer  2  via the electrical connection terminal  16 , so that a space (in the vertical direction in the drawing) between the interface module  10  and the interposer  2  needs to be adjusted into a predetermined height. 
         [0029]    On the other hand, the position of the guide pin  22  in a height direction in which the pin comes in contact with the opening edge of the reference hole  21  depends on relative positional deviation, hole diameter or guide pin diameter, and hence does not become constant. Therefore, a height adjustment mechanism is required for setting the space to a predetermined value. This height adjustment mechanism is realized as follows. The mechanism will be described with reference to  FIGS. 3A to 3D . 
         [0030]    First, as shown in  FIG. 3A , the interface module  10  is set from the upside so that the distal end of the guide pin  22  enters the reference hole  21  of the interposer  2 . Then, as shown in  FIG. 3B , when the tapered portion of the guide pin  22  is pressed onto the opening edge of the reference hole  21 , the center positions of the guide pin  22  and the reference hole  21  are self-aligned and guided to substantially match with each other. At this time, the electrical connection terminal  16  is not connected to the electrical wiring line  4 . Here, the guide pin  22  may be inserted into the holding hole  23  and fixed tentatively. Alternatively, the guide pin may be pressed into the holding hole  23  immediately before the interface module  10  is connected to the interposer  2 . 
         [0031]    Subsequently, as shown in  FIG. 3C , the interface module  10  is pressed to increase a load, whereby the preliminarily fixed (semi-fixed) guide pin  22  starts sliding upwards in the holding hole  23 . Then, as shown in  FIG. 3D , while holding the relative positions of the interface module  10  and the interposer  2  in the in-plane direction, the space between the interface module  10  and the interposer  2  is narrowed. Finally, when the electrical connection terminal  16  comes in contact with the electrical wiring line  4 , the load is scattered over a plurality of electrical connection terminals  16  to stop the sliding of the guide pin  22 , whereby the positioning and the electrical connection are completed. 
         [0032]    Here, the guide pin  22  is provided with the tapered portion, and this tapered portion is brought into the opening edge of the reference hole  21 . Therefore, even if there are variations in the pin diameter and hole diameter, the center of the guide pin  22  finally substantially matches with the center of the reference hole  21 . Therefore, the package is not influenced by the variations of the pin diameter and hole diameter. 
         [0033]    A mechanism for the positioning by use of a pair of guide pin  22  and reference hole  21  has been described above. However, when the pair of guide pin and reference hole are used, deviation is produced owing to the direction of rotation around the axis of the guide pin  22  as a rotary shaft. Therefore, in a usual pattern which is not uniform in the direction of rotation, for example, a concentric circle pattern, the positioning cannot be performed. Therefore, two or more pairs of pins and holes at minimum are necessary. A case where two pairs of pins and holes are used will further be described with reference to  FIGS. 4A and 4B  and  FIGS. 5A to 5D . 
         [0034]    When a plurality of positioning pins are used, the pitch between the guide pins  22  usually does not match with that between the reference holes  21 . Therefore, as shown in  FIGS. 4A and 4B , one of the pitches becomes large.  FIG. 4A  shows a case where the pitch between the guide pins  22  is larger, and  FIG. 4B  shows a case where the pitch between the reference holes  21  is larger. As seen from  FIGS. 4A and 4B , in either case, the interface module is guided so that the center positions of the two guide pins  22  substantially match with those of the reference holes  21 . Therefore, the positions of the electrodes of the interposer  2  and interface module  10  are determined based on the center positions, whereby the influences of positional deviations due to the pitch deviations of the guide pins  22  and reference holes  21  can be eliminated. 
         [0035]    On the other hand, a method of inserting, into a reference hole  121 , a guide pin  122  having a diameter smaller than that of the reference hole  121  as in a comparative example is shown in  FIGS. 5A to 5D . In this case, when a pitch between the guide pins  122  is large as shown in  FIG. 5A , or when a pitch between the reference holes  121  is large as shown in  FIG. 5B , the guide pins  122  need to be inserted into the reference holes  121 . Therefore, as shown in  FIG. 5C , a clearance  120  between the guide pin  122  and the reference hole  121 , corresponding to a maximum pitch deviation, is necessary. Then, as shown in  FIG. 5D , a center position deviation A corresponding to the maximum pitch deviation is produced, and a positioning error is unnecessarily added, so that it becomes difficult to perform highly precise positioning. 
         [0036]    Next, an arrangement relation between the guide pins  22  and the reference holes  21  will be described with reference to  FIGS. 6A and 6B . 
         [0037]    In  FIG. 6A , the arrangement of the guide pins  22  and the reference holes  21  is set to the vicinity of the diagonal line of a substrate. In this case, the center position of the substrate substantially matches with the center positions between the guide pins  22  and between the reference holes  21 , so that there are many advantages. For example, when the package is assembled with an automatic machine, the rotary center is advantageously substantially matched. 
         [0038]    When two pairs of guide pins and reference holes are used, there remains a component rotating around a line connecting the two pairs to each other as an axis. Therefore, in consideration of a large possibility of eccentricity in a case where a load is applied, as shown in  FIG. 6B , more than two pairs of guide pins  22  and reference holes  21  may be used. In this case, the clearances formed by the tapered portion may be large to such an extent that the tapered portions of the remaining guide pins  22  are pressed onto the reference holes  21  with respect to the relative position determined by two of the plurality of pairs. Moreover, the load can be supported by a plurality of guide pins. In consequence, there is an advantage that the balance of the load improves. 
         [0039]    It is to be noted that when a pair of guide pin  22  and reference hole  21  are used, they deviate in the direction of rotation, and cannot be positioned, but a stop for regulating the deviation in the direction of rotation may be provided so that this deviation is eliminated. In this case, the central position cannot be defined, but only one point of an engagement portion can be matched. Therefore, in the interposer  2  and the interface module  10 , a wiring line pattern or the like may be formed based on the reference hole  21  and the guide pin  22 . 
         [0040]      FIG. 7  is a perspective view showing the mounting state of the package provided with a high-speed interface module according to the present embodiment. 
         [0041]    After the interposer  2  including the signal processing LSI  1  mounted thereon is mounted together with another mounting component on a mounting board  30 , the interface module  10  is mounted on the interposer  2  as shown by an arrow in the drawing. At this time, the guide pins  22  of the interface module  10  are aligned with the reference holes  21  of the interposer  2 , whereby the interface module  10  and the interposer are precisely positioned. It is to be noted that reference number  32  is a wiring line on the mounting board  30 , and  33  is a chip component. Moreover, the ends of the transmission lines  11  including optical fibers opposite to the optical interface module  10  are connected to an optical connector  31  for connection to external optical fibers. 
         [0042]    Thus, the optical connector  31  is connected to a place away from the optical interface module  10 , whereby mounting restrictions imposed by the enlarged optical connector structure can be solved. 
         [0043]    Moreover, after finishing electrical mounting by a method of soldering the interposer  2  on which the signal processing LSI  1  is mounted together with the other mounting components (e.g., chip components such as a capacitor and a reactance, peripheral LSI and IC, etc.) by a usual reflow step or fitting these components into sockets, the interface module  10  can be attached later only by mechanical connection without adding any thermal history to the module. Therefore, the transmission lines for use in the interface module  10  can be selected without being limited by any mounting step. Therefore, an appropriate material can be selected in accordance with a transmission distance, frequency or cost, and the whole cost can effectively be decreased. 
         [0044]    As described above, according to the present embodiment, the interposer  2  is provided with the reference hole  21  for positioning, whereas the interface module  10  is provided with the preliminarily fixed (semi-fixed) guide pin  22  having a tapered thinned shape in which the diameter of a cylinder portion is larger than that of the reference hole  21  and the diameter of a distal end is smaller than that of the reference hole  21 . In consequence, the interposer  2  and the interface module  10  can precisely be positioned in an in-plane direction in a state in which the tapered portion of the guide pin  22  is pressed onto the circumferential edge of the reference hole  21  on the surface of the substrate. In addition, the guide pin  22  is slid into the holding hole  23  so that a predetermined space is made between the interface module  10  and the interposer  2 , whereby the space between the interface module  10  and the interposer  2  can be adjusted (height adjustment). Therefore, the pitch narrowing involving a large number of pins for electrical connection can be achieved, and the LSI package with the interface module capable of transmitting a large capacity can be realized. 
         [0045]    Moreover, only the reference holes  21  may be formed in the interposer  2 , so that the existing LSI package assembly step (e.g., the reflow step or the like) may be applied as it is. This also produces an advantage that line adjustment or reconstruction does not have to be performed. 
       Second Embodiment 
       [0046]      FIGS. 8A to 8D  are sectional views showing a part of an LSI package with an interface module according to a second embodiment of the present invention. It is to be noted that the same components as those of  FIGS. 3A to 3D  are denoted with the same reference numbers, and detailed description thereof is omitted. Moreover, the steps of  FIGS. 8A to 8D  correspond to those of  FIGS. 3A to 3D , respectively. 
         [0047]    The present embodiment is different from the first embodiment in that the middle portion of a guide pin  22  between the preliminarily fixed (semi-fixed) main body portion of the pin and the tapered portion thereof is provided with a stop portion  24  having a diameter which is discontinuously larger than that of the main body portion. That is, the distal end (the minimum diameter) of the tapered portion of the guide pin  22  is smaller than the diameter of a reference hole  21 , and the proximal end (the maximum diameter) of the tapered portion is larger than the reference hole  21  and is also larger than a holding hole  23 . In this case, the diameter of the main body of the guide pin  22  (the diameter of a portion to be inserted into the holding hole  23 ) does not have to be necessarily larger than the reference hole  21 . As long as the minimum diameter of the tapered portion of the main body of the guide pin  22  is smaller than the reference hole  21  and the maximum diameter of the tapered portion is larger than the reference hole  21 , the diameter of the main body of the guide pin  22  may be smaller than that of the reference hole  21 . 
         [0048]    According to such a constitution, the relative positions of an interposer  2  and an interface module  10  in an in-plane direction are determined, and then the guide pin  22  starts to slide in the holding hole  23 , whereby electrical connection terminals come in contact with each other to achieve electrical connection. Here, if a large load is applied and the guide pin  22  further slides, the sliding is stopped in the stop portion  24 , so that electrical connecting portions can be inhibited from being excessively collapsed. In consequence, even if eccentricity is produced in the load and a force larger than a designed force is eccentrically applied, the sliding is stopped in the stop portion  24 , and the load is scattered to another guide pin  22 . This produces an effect that the uniform electrical connection can be performed. 
       Third Embodiment 
       [0049]      FIG. 9  is a sectional view showing a part of an LSI package with an interface module according to a third embodiment of the present invention. It is to be noted that the same components as those of  FIG. 2  are denoted with the same reference numbers, and detailed description thereof is omitted. 
         [0050]    In the present embodiment, an interposer  2  is provided with a coarse positioning second reference hole  41  separately from a first reference hole  21 . This reference hole  41  is provided so that the hole extends from the front surface of the interposer  2  to the back surface thereof in a substantially vertical direction. The number of the reference holes  41  may be one or plural, but two or more second reference holes may preferably be required for securely performing coarse adjustment. 
         [0051]    On the other hand, a second guide pin  42  to be inserted into the second reference hole  41  is fixed to an interface module  10 . The diameter of this guide pin  42  is smaller than that of the reference hole  41 . Furthermore, the length of the second guide pin  42  is larger than that of the first guide pin  22 , so that the second guide pin  42  is inserted into the second reference hole  41  before the tapered portion of a first guide pin  22  comes in contact with the opening edge of a first reference hole  21 . 
         [0052]    According to such a constitution, the second guide pin  42  is inserted into the second reference hole  41 , whereby the relative positions of the interface module  10  and the interposer  2  in an in-plane direction can be coarsely adjusted. In consequence, the positioning can be coarsely performed in advance with the second guide pin  42  and the second reference hole  41 , whereby the distal end of the guide pin  22  can be prevented from being detached from the reference hole  21 , and the positioning can quickly and securely be performed. 
         [0053]    It is to be noted that even in the third embodiment, two or more pairs of first guide pins  22  and first reference holes are preferably provided. Moreover, the first guide pin  22  may be provided with a stop portion  24  as shown in  FIGS. 8A to 8D . The upper surface of the interface module  10  may substantially be the same plane as the upper surface of the signal processing LSI (not shown) of the interposer, whereby a heat sink can preferably easily be mounted. 
         [0054]    (Modification) 
         [0055]    It is to be noted that the present invention is not limited to the above embodiments. In the first to third embodiments, a case where a movable guide pin is preliminarily fixed on the side of an interface module has been described. Conversely, the guide pin may preliminarily be fixed on the side of an interposer, and a reference hole may be provided on the side of an interface module. Moreover, a pair of guide pin and reference hole or a plurality of pairs of guide pins and reference holes may be provided. However, to exactly define a central position between the guide pins, two or more pairs are preferable. 
         [0056]    Moreover, a technique for installing the guide pin in a preliminarily fixed state is not limited to a case where the diameter of the main body portion of the guide pin is set to a diameter equal to that of a holding hole to press the guide pin into the holding hole, thereby holding the pin. Alternatively, a mechanism for exclusive use in holding the guide pin in the preliminarily fixed state may be provided. 
         [0057]    In the third embodiment, a stational guide pin is fixed on the side of the interface module, and the reference hole is provided on the side of the interposer, but this may be reversed. Moreover, a movable guide pin and the stational guide pin may be provided on the same side of the interface module or the interposer, or may be provided on both the sides so that the pins face each other. 
         [0058]    Furthermore, the electrical connection terminals are not necessarily limited to bumps, and may have a structure in which stud bumps are formed, and crushed with an ultrasonic wave or the like so that they are bonded. In addition, to improve the reliability of a bonded portion, an underfill resin may be inserted thereto. Further, a cross section of a hole, pin, cylinder portion and so forth may not be a real circle. 
         [0059]    Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.