Abstract:
An apparatus is provided for supporting a PCB substrate during printing. The apparatus includes first and second fixing units that cooperate to edge-clamp the substrate. The first fixing unit includes a first movable plate, a first actuator, and a first stopper that limits outward movement of the first movable plate. The second fixing unit includes a second movable plate, a second actuator, and a second stopper that limits outward movement of the second movable plate. When printing the substrate from the first edge to the second edge, the first and second fixing units operate so that the second actuator moves the second movable plate outwardly to contact the second stopper, and the first actuator moves the first movable plate inwardly to press the substrate toward the second movable plate. When printing the substrate from the second edge to the first edge the first and second fixing units operate oppositely.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2006-0100013, filed on Oct. 13, 2006, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to printed circuit boards (PCBs). More particularly, the present invention relates to an apparatus for supporting a PCB substrate while a printing apparatus applies solder paste on a surface of the substrate, and a method of forming the PCB using the apparatus. 
         [0004]    2. Description of the Related Art 
         [0005]    Various electronic components are mounted on a surface of a printed circuit board (PCB). Conventionally, PCBs are mass-produced by automated equipment through various processes including a screen printing process, a component mounting process, a reflow process, etc. 
         [0006]    In the screen printing process of PCB mass production, solder paste in a melted state is applied in a predetermined pattern on a substrate surface so that various electronic components of various shapes may be surface-mounted on the PCB to be in communication with each other. The solder paste is applied using an apparatus called a screen printer. The screen printer presses the solder paste supplied on a mask or a screen having a predetermined pattern with a squeegee and applies the pressed solder paste on the PCB. 
         [0007]    When the solder paste is applied on the substrate, a PCB supporting apparatus operates to fix (i.e., hold stationary, clamp or secure) the PCB so that the PCB does not move. The PCB supporting apparatus includes an air cylinder pressing a side surface of the PCB to fix the PCB in order to minimize a movement of the PCB during a printing process. 
         [0008]      FIG. 1  is a plan view illustrating a conventional PCB supporting apparatus and  FIG. 2  is a side view illustrating the PCB supporting apparatus of  FIG. 1 . 
         [0009]    The conventional PCB supporting apparatus presses side surfaces or edges of a PCB  10  to fix the PCB  10 . The conventional PCB supporting apparatus includes a stationary plate  11  supporting one edge of the PCB  10  and a movable plate  12  pressing the other edge of the PCB  10 . The movable plate  12  is operated by an air cylinder  13  to press the other edge of the PCB  10 . When the PCB  10  is pressed and fixed between the stationary plate  11  and the movable plate  12 , a printing operation of applying solder paste on the PCB  10  is then performed. 
         [0010]    In the printing operation of applying solder paste on the PCB  10 , the solder paste that is supplied on a mask or screen is pressed on the PCB  10  by a squeegee. Therefore, a pressure is applied to the PCB  10  in a printing direction, that is, a direction towards where the squeegee presses the solder paste on the PCB  10 . 
         [0011]    A squeezing pressure ranges from 3 to 20 kg/cm 2 . On the other hand, the pressure applied to the movable plate  12  by the air cylinder  13  is at the most approximately 2 kg/cm 2 . Therefore, when the printing operation of applying solder paste on the PCB  10  is performed and a high squeezing pressure is applied while the air cylinder  13  presses and supports the PCB  10  with low pressure, the PCB  10  may move when, for example, the printing direction is from the stationary plate  11  toward the movable plate  12 . 
         [0012]    If the PCB  10  moves in the printing direction when printing for minute components (e.g., having dimensions of approximately 0.3-0.6 mm) is performed on the PCB  10 , a small movement of the PCB  10  in the printing direction greatly affects the printing operation, and thus degrades the printing quality. 
         [0013]    The pressure applied to the PCB  10  by the air cylinder  13  may be increased in order to prevent the PCB  10  from moving, but the PCB  10  may be bent, bowed or damaged due to the applied high pressure. 
       SUMMARY OF THE INVENTION 
       [0014]    According to an aspect of the present invention, there is provided an apparatus that supports a substrate during a printing operation for printed circuit board (PCB) formation. An example apparatus includes: a first fixing unit including a first movable plate that engages the first edge of the PCB substrate, a first actuator that moves the first movable plate in a first inward direction toward the first edge and a first outward direction away from the first edge, and a first stopper that limits movement of the first movable plate in the first outward direction; and a second fixing unit including a second fixing unit generally parallel with and spaced apart from the first fixing unit, the second fixing unit including a second movable plate that engages the second edge of the PCB substrate, a second actuator that moves the second movable plate in a second inward direction toward the second edge and a second outward direction away from the second edge, and a second stopper that limits movement of the second movable plate in the second outward direction. When solder paste is printed on the PCB substrate from the first edge to the second edge, the apparatus operates such that the second actuator moves the second movable plate in the second outward direction to contact the second stopper, and the first actuator moves the first movable plate in the first inward direction to press the PCB substrate toward the second movable plate. Similarly, when solder paste is printed on the PCB substrate from the second edge to the first edge, the apparatus operates such that the first actuator moves the first movable plate in the first outward direction to contact the first stopper, and the second actuator moves the second movable plate in the second inward direction to press the PCB substrate toward the first movable plate. 
         [0015]    The apparatus may further include a PCB conveying apparatus that delivers the PCB between the first and second fixing units. 
         [0016]    The apparatus may further include a lower support unit that supports a bottom surface of the PCB and which adjusts the height of the PCB to correspond substantially with the height of the first and second movable plates of the first and second fixing units. 
         [0017]    The apparatus may further include a vacuum nozzle that applies a vacuum pressure to the bottom surface of the PCB. 
         [0018]    The first and second fixing units may be movable relative to each other such that a distance between the first and second fixing units is adjusted to correspond to the width of the PCB. 
         [0019]    According to another aspect of the present invention, there is provided a method of forming of a printed circuit board (PCB) using the apparatus for supporting a PCB, the apparatus including first and second fixing units, the method including: loading a PCB in a predetermined region of the apparatus between the first and second fixing units; determining whether a printing direction of a printing apparatus is a first direction proceeding from a first side of the PCB to a second side of the PCB or a second direction from the second side of the PCB to the first side of the PCB; when the printing direction of the printing apparatus is the second direction, fixing a first fixing unit to support the first side of the PCB, and pressing the PCB toward the first fixing unit with the second fixing unit; when the printing direction is the first direction, fixing the second fixing unit to support the second side of the PCB, and pressing the PCB toward the second fixing unit with the first fixing unit; and performing a printing operation by applying solder paste on the PCB with the printing apparatus. 
         [0020]    The loading of the PCB may include conveying the PCB between the first and second fixing units by a PCB conveying apparatus. 
         [0021]    The performing of the printing operation may include aligning the PCB before applying the solder paste on the PCB. 
         [0022]    The performing of the printing operation may further include supporting the PCB by applying a vacuum to a bottom pressure surface of the PCB after the aligning of the PCB. 
         [0023]    In the method, the first fixing unit may include a first movable plate that engages the first edge of the PCB substrate, a first actuator that moves the first movable plate in a first inward direction toward the first edge and a first outward direction away from the first edge, and a first stopper that limits movement of the first movable plate in the first outward direction, and the second fixing unit may include a second movable plate that engages the second edge of the PCB substrate, a second actuator that moves the second movable plate in a second inward direction toward the second edge and a second outward direction away from the second edge, and a second stopper that limits movement of the second movable plate in the second outward direction, and the fixing of the first fixing unit and the second fixing unit may be performed using a driving force applied from the first and second actuators 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0024]      FIG. 1  is a plan view illustrating a conventional printed circuit board (PCB) supporting apparatus; 
           [0025]      FIG. 2  is a side view illustrating the conventional PCB supporting apparatus of  FIG. 1 ; 
           [0026]      FIG. 3  is a perspective view illustrating an example printing apparatus including a PCB supporting apparatus according to an embodiment of the present invention; 
           [0027]      FIG. 4  is a partial perspective view illustrating the PCB supporting apparatus illustrated in  FIG. 3 ; 
           [0028]      FIG. 5  is an enlarged perspective view illustrating part “A” of the PCB supporting apparatus illustrated  FIG. 4 ; 
           [0029]      FIG. 6  is a side elevation view illustrating the PCB supporting apparatus with a PCB conveyed illustrated in  FIG. 3 ; 
           [0030]      FIG. 7  is a side elevation view illustrating the PCB supporting apparatus in  FIG. 3  performing a printing operation from front to back invention; 
           [0031]      FIG. 8  is a plan view schematically illustrating an operation state of the PCB supporting apparatus illustrated in  FIG. 7 ; 
           [0032]      FIG. 9  is a side elevation view illustrating the PCB supporting apparatus in  FIG. 3  performing a printing operation from back to front; 
           [0033]      FIG. 10  is a plan view schematically illustrating an operation state of the PCB supporting apparatus illustrated in  FIG. 9 ; and 
           [0034]      FIG. 11  is a flowchart illustrating an example method of forming a PCB using the PCB supporting apparatus. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0035]    The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. 
         [0036]      FIG. 3  is a perspective view illustrating a printing apparatus including an example printed circuit board (PCB) supporting apparatus according to an aspect of the present invention,  FIG. 4  is a perspective view illustrating the PCB supporting apparatus illustrated in  FIG. 3 ,  FIG. 5  is an enlarged perspective view illustrating part “A” of the PCB supporting apparatus illustrated  FIG. 4 , and  FIG. 6  is a side elevation view illustrating the PCB supporting apparatus with a PCB conveyed illustrated in  FIG. 3 . For sake of convenience, the terms substrate and PCB will be used somewhat interchangeably herein since it should be appreciated that the present apparatus receives substrates for the purpose of facilitating the printing of circuit traces thereon and, thereby, forming PCBs. 
         [0037]    Referring to  FIGS. 3 through 6 , the PCB supporting apparatus includes a first fixing unit  110  and a second fixing unit  120 . The PCB supporting apparatus fixes (i.e., holds stationary, clamps, retains, secures) the PCB  90  between the first and second fixing units  110  and  120  while the printing apparatus performs a printing operation (i.e., applying solder paste) on the PCB  90 . Therefore, the first and second fixing units  110  and  120  are configured to be generally parallel to each other, spaced apart a predetermined distance, and facing each other so as to support the first edge  91  (front edge according to arrow labelled “FRONT” in  FIG. 3 ) and the second edge  92  (back edge according to arrow labelled “BACK” in  FIG. 3 ) of the PCB  90 , respectively. 
         [0038]    The first fixing unit  110  of the PCB supporting apparatus supports the first edge  91  of the PCB  90  and includes a first movable plate  112 , a first actuator  113  and a first stopper  114 . The first movable plate  112  of the first fixing unit  110  is movably mounted, coupled or otherwise configured on a first guide unit  111  for horizontal movement in the y-axis direction. As shown in  FIG. 4 , the first guide unit  111  is mounted on a base  100 . The first movable plate  112  of the first fixing unit  110  may move along the y-axis in an inward (i.e., backward) direction towards the first edge  91  of the PCB  90 , and an outward (i.e., frontward) direction away from the first edge  91  of the PCB  90 . As best illustrated in  FIGS. 3 and 4 , the first movable plate  112  extends in the x-axis direction along a substantial length of the guide unit  111 . 
         [0039]    Various means or devices may be employed to move the first movable plate  112  of the first fixing unit  110  in the y-axis direction on the first guide unit  111  but in the illustrated embodiment, a linear movement guide  115  and guide block  116  are used to facilitate movement of the first movable plate  112  in an inward and outward direction on the first guide unit  111 . The linear movement guide  115  is mounted on the first guide unit  111 , and a slidable guide block  116  is coupled to the linear movement guide  115  and is mounted on the first movable plate  112 . Therefore, the first movable plate  112  may move in an inward and outward direction along with the linear movement guide  115 . 
         [0040]    The first actuator  113  of the first fixing unit  110  is mounted on the first guide unit  111  and is connected to the first movable plate  112  to supply a driving force to the first movable plate  112 . In an embodiment, the first actuator  113  of the first fixing unit  110  comprises an air (i.e., pneumatic) cylinder, and a cylinder rod  117  of the air cylinder is connected to the first movable plate  112  through a connecting block  118 . Therefore, when the cylinder rod  117  of the air cylinder extends or retracts by an operation of the first actuator  113 , a driving force is transferred to the first movable plate  112 , and thereby moving the first movable plate  112  on the first guide unit  111 . In other embodiments, the first actuator  113  may be other suitable devices such as electric actuators, hydraulic actuators, etc. 
         [0041]    The first stopper  114  of the first fixing unit  110  is mounted on an outer portion of the linear movement guide  115 . The first stopper  114  limits an outward movement of the first movable plate  112  away from the first edge  91  of the PCB  90 . When the first movable plate  112  moves outward away from the first edge  91  of the PCB  90  due to the first actuator  113  and reaches the first stopper  114 , the first movable plate  112  is stopped. Therefore the first movable plate  112  cannot move outward away from the first edge  91  of the PCB  90  anymore due to the first stopper  114 . In such a stopped state, the first movable plate  112  is configured to best support the first edge  91  of the PCB  90 . 
         [0042]    The second fixing unit  120  of the PCB supporting apparatus is configured generally parallel to, and spaced apart from the first fixing unit  110  to support the second edge  92  of the PCB  90 . The second fixing unit  120  includes a second movable plate  122 , a second actuator  123  and a second stopper  124  (refer to  FIGS. 7 and 9 ). As can be appreciated, the second fixing unit  120  of the PCB supporting apparatus is substantially similar to or a substantial mirror-image of the first fixing unit  110 . 
         [0043]    The second movable plate  122  of the second fixing unit  120  is mounted on a second guide unit  121  mounted on the base  100  and can horizontally move along the y-axis direction. The second movable plate  122  may move in an inward (i.e., frontward) direction towards the second edge  92  of the PCB  90 , and an outward (i.e., backward) direction away from the second edge  92  of the PCB  90 . As best illustrated in  FIGS. 3 and 4 , the second movable plate  122  extends in the x-axis direction along a substantial length of the second guide unit  121 . 
         [0044]    The second movable plate  122  is moved by the second actuator  123 , and is coupled to a linear movement guide (not shown) mounted in the second guide unit  121  to move in an inward or outward direction towards and away from the second edge  92  of the PCB  90 . The second stopper  124  is mounted on the linear movement guide to limit an outward movement of the second movable plate  122  away from the second edge  92  of the PCB  90 . 
         [0045]    In an embodiment, the first and second fixing units  110   120  may be movable relative to each other on the base  100  such that a distance between the first and second guide units  111 ,  121  may be adjusted. As best shown in  FIGS. 3 and 4 , in one embodiment, the second guide unit  121  may move by sliding along a guide  191  of the base  100 , and may be driven by a motor  192  to move toward or away from the first guide unit  111 . 
         [0046]    A PCB conveying apparatus  130  may be mounted between the first and second fixing units  110  and  120 . In an embodiment, the PCB conveying apparatus  130  may include a first conveyor belt  131  mounted on the first guide unit  111  and a second conveyor belt  132  mounted on the second guide unit  121  (refer to  FIG. 6 ). The first conveyor belt  131  supports a bottom surface of one side of the PCB  90  proximate to edge  91 , and the second conveyor belt  132  supports a bottom surface of the other side of the PCB  90  proximate to edge  92 . Therefore, when the first and second conveyor belts  131  and  132  rotate, the PCB  90  is conveyed, oriented, configured or otherwise delivered between the first and second fixing units  110  and  120 . 
         [0047]    The PCB supporting apparatus may further include a lower support unit  140  (refer to  FIG. 6 ) that is configured to support a bottom surface of the PCB  90 . The lower support unit  140  supports the bottom surface of the PCB  90  by moving in an upward direction under the PCB  90 , and thus may adjust the height of the PCB  90  to generally correspond to the height of the first and second movable plates  112  and  122  such that the PCB  90  is, for example, substantially coplanar with the plates  112 ,  122 . That is, when the PCB  90  is conveyed between the first and second fixing units  110  and  120 , the lower support unit  140  rises to support the PCB  90  and adjust the height of the PCB  90 . 
         [0048]    The lower support unit  140  includes a vertical movable plate  141  that moves in upward and downward directions from the base  100 . The lower support unit  140  further includes support wings  142  and support pins  143  that extend in an upward direction from the vertical movable plate  141 . The support wings  142  support both sides of the bottom surface of the PCB  90 , and the support pins  143  support a center portion of the bottom surface of the PCB  90 . 
         [0049]    The PCB supporting apparatus may further include a vacuum nozzle  150  that vertically fixes the PCB  90  by applying a vacuum to the bottom surface of the PCB  90 . The vacuum nozzle  150  can move in upward or downward directions together with the lower support unit  140 , such that the vacuum nozzle  150  fixes the PCB  90  by applying vacuum pressure to the bottom surface of the PCB  90  after the support wings  142  and the support pins  143  contact the bottom surface of the PCB  90 . 
         [0050]    An operation of the apparatus for supporting the PCB having the above-mentioned structure will now be described. 
         [0051]    The PCB  90  is loaded on the PCB conveying apparatus  130  of the PCB supporting apparatus, and conveyed between the first and second fixing units  110  and  120 . Before loading the PCB  90 , a distance between the first and second guide units  111  and  121  may be adjusted to generally correspond to the width of the PCB  90  (i.e., the distance between edges  91  and  92 ) by moving, for example, in one embodiment, the second guide unit  121  toward or away from the first guide unit  111 . 
         [0052]    Front and back ends of the bottom surface of the PCB  90  are supported by the first and second conveyor belts  131  and  132  of the PCB conveying apparatus  130 . Therefore, when the first and second conveyor belts  131  and  132  of the PCB conveying apparatus  130  rotate, the PCB  90  is conveyed between the first and second fixing units  110  and  120 . 
         [0053]    The first and second conveyor belts  131  and  132  of the PCB conveying apparatus  130  are configured to be lower than the first and second fixing plates  112  and  122 , such that the PCB  90  does not interfere with other parts such as the first and second fixing plates  112  and  122  while being conveyed by the first and second conveyor belts  131  and  132 . The lower support unit  140  adjusts the height of the conveyed PCB  90  to be substantially coplanar with the plates  112 ,  122  of first and second fixing units  110  and  120 . When the lower support unit  140  moves in an upward direction under the PCB  90 , the PCB  90  is supported by the support wings  142  and the support pins  143  that extend upward from the vertical movable plate  141 . The lower support unit  140  rises until the first and second sides of the PCB  90  are substantially coplanar with the first and second movable plates  112  and  122 . 
         [0054]      FIG. 7  is a side elevation view illustrating the PCB supporting apparatus in  FIG. 3  performing a printing operation in a front to back printing direction, and  FIG. 8  is a plan view schematically illustrating an operation state of the PCB supporting apparatus illustrated in  FIG. 7 . 
         [0055]    When the PCB  90  is substantially coplanar with the first and second movable plates  112  and  122 , the PCB  90  is supported therebetween according to a printing direction. In a printing operation, solder paste is applied on a surface of the PCB  90 . When solder paste is pressed on the PCB  90  by a squeegee, the printing direction of the solder paste may be from front to back of the PCB  90  or from back to front of the PCB  90 . A pressure is applied to the PCB  90  in the printing direction due to the squeegee, which causes the PCB  90  to move in the printing direction. To prevent movement of the PCB  90 , the moving direction of the PCB  90  is determined according to the printing direction, and the first and second fixing units  110  and  120  operate in order to prevent a movement of the PCB  90 . 
         [0056]    When the printing direction is from the first edge  91  of the PCB  90  to the second edge  92  of the PCB  90 , that is, from front to back, the PCB  90  tends to move backward due to pressure from the printing apparatus. In this case, the second movable plate  122  supporting the second edge  92  of the PCB  90  and the second stopper  124  operate such that the PCB  90  does not move in the printing direction. 
         [0057]    In this case, the second actuator  123  operates to move the second movable plate  122  in an outward direction such that a rear surface of the second movable plate  122  contacts the second stopper  124 . When the rear surface of the second movable plate  122  contacts the second stopper  124 , the second movable plate  122  cannot move anymore in an outward direction since the second stopper limits the outward movement of the second movable plate  122 . 
         [0058]    When the second movable plate  122  and the second actuator  123  has stopped operating, the first actuator  113  operates to move the first movable plate  112  in an inward direction, and thereby pressing or clamping the PCB  90  between the plates  112 ,  122 . As shown in  FIGS. 7 and 8 , the PCB  90  is supported by the support wings  142  and the support pins  143  of the lower support unit  140 , but is not fixed. Accordingly, when the first movable plate  112  presses the first edge  91  of the PCB  90 , the PCB  90  moves toward the second movable plate  122  and thus the second edge  92  contacts the second movable plate  122 . 
         [0059]    In this state, since the second edge  92  of the PCB  90  contacts the second movable plate  122  and the PCB  90  does not move further in a backward direction. Accordingly, the PCB supporting apparatus can stably support the PCB  90  during the printing operation. 
         [0060]      FIG. 9  is a side elevation view illustrating the PCB supporting apparatus in  FIG.3  performing a printing operation in a back to front printing direction, and  FIG. 10  is a plan view schematically illustrating an operation state of the PCB supporting apparatus illustrated in  FIG. 9 . 
         [0061]    When the printing direction is from the second edge  92  to the first edge  91  of the PCB  90 , that is, from back to front, the PCB  90  tends to move in the printing direction (frontwardly) due to pressure applied by the printing apparatus. In this case, the first movable plate  112  supporting the first edge  91  of the PBC  90  and the first stopper  114  operate such that the PCB  90  does not move frontwardly. 
         [0062]    In this case, the PCB  90  is fixed in an opposite manner to the PCB as shown in  FIGS. 7 and 8 . That is, the first actuator  113  operates to move the first movable plate  112  in an outward direction such that a rear surface of the first movable plate  112  contacts the first stopper  114 . When the rear surface of the first movable plate  112  contacts the first stopper  114 , the first movable plate  112  is fixed and thus cannot move further in an outward direction since the first stopper  114  limits the outward movement of the first movable plate  112 . 
         [0063]    When the first movable plate  112  is fixed and thus the first actuator  113  has stopped operating, the second actuator  123  operates to move the second movable plate  122  in an inward direction, thereby pressing or clamping the PCB  90  against the first movable plate  112 . As illustrated in  FIGS. 9 and 10 , the PCB  90  is supported by the support wings  142  and the support pins  143  of the lower support unit  140 , but is not fixed. Accordingly, when the second movable plate  122  presses the second edge  92 , the PCB  90  moves toward the first movable plate  112  and thus the first edge  91  contacts the first movable plate  112 . 
         [0064]    In this state, since the first edge  91  of the PCB  90  contacts the first movable plate  112  and the PCB  90  does not move anymore in a forward direction. Accordingly, the PCB supporting apparatus can stably support the PCB  90  during the printing operation. 
         [0065]    When the PCB  90  is supported between the first and second fixing units  110  and  120  according to the printing direction, the vacuum nozzle  150  operates to support the PCB  90  such that a vertical orientation thereof is maintained by applying a vacuum pressure to the bottom surface of the PCB  90 . 
         [0066]    When the supporting of the PCB  90  is established, the PCB  90  may be aligned for a printing operation. In an embodiment, the PCB  90  is aligned for the printing operation with an aligning apparatus  160  that is configured under the base  100  (refer to  FIG. 3 ). The aligning apparatus  160  moves the base  100  in x-axis and y-axis directions or rotates the base  100  to adjust an angle of the base  100 , and thereby adjusting a position of the PCB  90  for the printing operation. 
         [0067]    When the aligning of the PCB  90  is completed, the printing operation is performed to apply solder paste in a predetermined pattern on a surface of the PCB  90 . When the printing operation of the PCB  90  is completed, the PCB  90  is conveyed through the PCB conveying apparatus  130  and discharged from the printing apparatus. Next, another PCB is conveyed through the PCB conveying apparatus  130 , and the above-described operations are repeated. 
         [0068]      FIG. 11  is a flowchart illustrating an example method of forming a PCB according to another aspect of the present invention. 
         [0069]    The example method of forming the PCB according to an embodiment of the present invention includes: loading the PCB into a printing apparatus that includes the forgoing-described supporting apparatus with first and second fixing units (S 100 ), determining a printing direction (S 200 ); relative to the determining step, either first fixing of the PCB (S 300 ) or second fixing of the PCB (S 400 ); aligning the PCB (S 500 ) and printing (S 600 ). 
         [0070]    In operation S 100 , the PCB  90  for a printing operation is loaded on a predetermined region of the printing apparatus that includes the forgoing-described supporting apparatus with first and second fixing units, in between the first and second fixing units. The PCB  90 , which is supplied to a PCB supporting apparatus, may be, for example, conveyed between the first fixing unit  110  and the second fixing unit  120  by the PCB conveying apparatus  130 . Next, the PCB  90  may be moved in an upward direction by the lower support unit  140  so that the height of the PCB  90  is adjusted to generally correspond to the height of the first and second movable plates  112  and  122  of the first and second fixing units  110 ,  120 . 
         [0071]    In operation S 200 , the direction of the printing operation of applying solder paste on a surface of the PCB  90  is determined. The printing direction may be a first direction that proceeds from the first edge  91  of the PCB  90  to the second edge  92  of the PCB  90 , or a second direction that proceeds from the second edge  92  of the PCB  90  to the first edge  91  of the PCB  90 . 
         [0072]    Since pressure is applied to the PCB  90  in the printing direction, an appropriate fixing operation for the PCB is performed depending on the printing direction that is determined in operation S 200 . 
         [0073]    When the printing direction is the second direction, the first fixing operation S 300  is performed. That is, the first movable plate  112  of the first fixing unit  110  is fixed to support the first edge  91  of the PCB  90 , and the second fixing unit  120  presses the PCB  90  towards the first fixing unit  110 . 
         [0074]    When the printing direction is the first direction, the second fixing operation S 400  is performed. That is, the second movable plate  122  of the second fixing unit  120  is fixed to support the second edge  92  of the PCB  90 , and the first fixing unit  110  presses the PCB  90  towards the second fixing unit  120 . 
         [0075]    When the PCB  90  is fixed between the plates  112 ,  122 , the printing operation S 600  is performed. In operation S 600 , solder paste is applied on a surface of the PCB  90  to have a predetermined pattern. The operation S 600  may include or be proceeded by an aligning operation S 500 . In operation S 500 , a position of the PCB  90  is adjusted before applying the solder paste. The operation S 600  may further include a vacuum applying operation (not shown). In the vacuum applying operation, the vacuum nozzle  150  applies a vacuum to the bottom surface of the PCB  90  to prevent the PCB  90  from moving vertically, for example, after the aligning operation S 500 . 
         [0076]    As described above, according to an apparatus for supporting a PCB and the method of forming the PCB, the PCB can be better supported during a printing operation since the PCB supporting is changed depending on a printing direction. 
         [0077]    While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those 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 present invention as defined by the following claims.