Abstract:
The present invention relates to a container for holding paste used for making reflow soldering to fix surface mounted components (semiconductors, diodes, resistors, and so on) to a circuit on a printed circuit board. More specifically, the present invention relates to a container for automatically dispensing paste in a paste printer which can make automatic fixed amount dispensing of paste to a stencil of the paste printer. The container comprises a body including an opening, a supply hole in a center of a bottom for supply of the paste, and a press member movably mounted in the body and including a rim, and a sloped portion and a deforming portion both continuous from the rim inwardly, thereby making automatic dispensing of the paste to the upper surface of the stencil through the supply hole.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present invention claims the benefit of priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2008-0050364, filed on May 29, 2008, having a translated title of “CONTAINER FOR AUTOMATICALLY DISPENSING PASTE IN A PASTE PRINTER,” the content of which is incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. The Field of the Invention 
         [0003]    The present invention relates to a container for paste used to make reflow soldering to fix surface mounted components (semiconductors, diodes, resistors, etc.) on a circuit on a printed circuit board. More specifically, the present invention relates to a container for automatically dispensing paste to a stencil of a paste printer. 
         [0004]    2. The Relevant Technology 
         [0005]    In general, in order to make automatic mounting of a component by using a surface mounting device (SMD), it is required to apply paste to a required thickness in the same shape as a pad on the printed circuit board the component to be mounted thereon. 
         [0006]    Accordingly, it is required that the paste is automatically printed on the surface of the printed circuit board in the same shape as the component to be mounted thereon by using the paste printer in an entire process of the surface mounting device. 
         [0007]      FIG. 1  illustrates an operation principle of the paste printer schematically, and  FIG. 2  illustrates a top view of one example of a stencil used for a paste printer, wherein pass through holes  2   a  in the stencil  2  having the same shapes with pads  1   a  printed on a surface of the printed circuit board  1  are formed as shown in  FIG. 2 , and a squeegee  4  is mounted on the stencil to be movable back and forth to scratch the paste  3  applied to the stencil  2  to print the paste on the pad  1   a  in the same shape as the pass through hole  2   a.    
         [0008]    Accordingly, upon putting the squeegee into operation after manual or automatic introduction of the printed circuit board  1  under the stencil  2  having the pads  1   a  thereon facing upward and dipping out and manual application of a fixed amount of the paste  3  from a container (not shown) to an upper surface of the stencil  2 , the squeegee moves along the upper surface of the stencil  2 , scratching the paste  3  from the upper surface of the stencil  2  to transfer a fixed amount of the paste to the pads  1   a  on the printed circuit board  1  through the pass through holes  2   a  in the stencil  2  in a predetermined thickness. Then, in a following component surface mounting process, the surface mounting device mounts the component on the upper surface of the paste automatically, and in a final process of the reflow soldering, the mounted components Mare soldered automatically. 
         [0009]      FIG. 3  illustrates a longitudinal section of the related art paste container  5  for holding the paste  3 , provided with an opening  5   a  closed with a cover  6  so that the worker is required to open the cover  6 , dip out the paste  3  from the container  5  though the opening  5   a , and supply the paste  3  to an upper side of the stencil  2  manually for the transfer of the paste later. 
         [0010]    However, the worker&#39;s manual dipping out and supply of the paste from the container to the stencil in the paste printer requires a man assigned for the supply of the paste without fail, thereby increasing production costs due to additional labor cost and increasing failure of automation of an expensive apparatus. 
         [0011]    Moreover, the dependence of the amount of paste supplied to the upper surface of the stencil on skill of the worker deteriorates the uniformity of quality of products. 
         [0012]    Accordingly, object of the present invention is to provide a container for automatically dispensing paste in a paste printer, which can automatically dispense a fixed amount of paste to an upper surface of a stencil of the paste printer by using separate driving means once the container is loaded over the stencil of the paste printer while the container serves as a container for holding paste in a general storage state. 
         [0013]    Another object of the present invention is to provide a container for automatically dispensing paste in a paste printer, which can automatically dispense a fixed amount of paste for reducing a labor cost, and realizing automation of an expensive apparatus to enable mass production of good quality products. 
       BRIEF SUMMARY OF THE INVENTION 
       [0014]    To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a container for automatically dispensing paste in a paste printer to an upper surface of a stencil comprises a body including an opening, a supply hole in a center of a bottom for supply of the paste, and a cap for closing the supply hole in case of storage or transportation, and opening the supply hole in case of loading the body on the paste printer, and a press member movably mounted in the body, including a rim, and a sloped portion and a deforming portion both continuous from the rim inwardly, for serving as a cover in storage and transportation and moving inwardly by a pressing force of a pusher such that the rim is in close contact with an inside surface of the body for the press member to serve as a piston in a state the container is loaded on the paste printer, thereby making automatic dispensing of the paste to the upper surface of the stencil through the supply hole. 
         [0015]    The present invention has following advantageous effects. 
         [0016]    First, the closure of the supply hole in the center of the bottom of the body with the cap and the press member covering the body in a general state permits safe storage and transportation of the paste. 
         [0017]    Second, if the cap is removed from the supply hole, the body is loaded on the paste printer, and the press member is pressed down with the pusher, the press member serves as a piston by a pressing force of the pusher and it permits automatic dispensing of the paste to the upper surface of the stencil without addition of worker, thereby reducing production costs. 
         [0018]    Third, the automatic dispensing of the paste to the upper side of the stencil permits improvement of quality. 
         [0019]    These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only illustrated embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
           [0021]      FIG. 1  illustrates a principle of a paste printer, schematically; 
           [0022]      FIG. 2  illustrates a plan view an exemplary stencil used for a paste printer; 
           [0023]      FIG. 3  illustrates a longitudinal section of a related art paste container; 
           [0024]      FIG. 4  illustrates a perspective sectional view of a container in accordance with one embodiment of the present invention; 
           [0025]      FIGS. 5A and 5B  illustrate cross sectional views of the container in  FIG. 4  respectively, wherein 
           [0026]      FIG. 5A  illustrates a cross sectional view of the container in  FIG. 4  with the paste filled therewith, and 
           [0027]      FIG. 5B  illustrates a cross sectional view of the container in  FIG. 4  with the paste pressed down by a pressing member pushed with a pusher in a state a supply hole is opened; 
           [0028]      FIG. 6  illustrates a cross sectional view of a pressing member in accordance with an embodiment of the present invention; and 
           [0029]      FIG. 7  illustrates a partial section of a body of a container in accordance with an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]    Reference will now be made in detail to the specific embodiments of the present invention, examples of which are illustrated in the accompanying drawings  FIGS. 4 to 7 . Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. 
         [0031]      FIG. 4  illustrates an exploded perspective view of a container in accordance with an embodiment of the present invention, and  FIGS. 5A and 5B  illustrate cross sectional views of the container in  FIG. 4  respectively. 
         [0032]    Referring to  FIGS. 4 ,  5 A and  5 B, the container includes a body  11  having an opening  11   a  and a supply hole  11   b  in a center of a bottom for supply of paste  3 , with a cap  12  for closing the supply hole  11   b  in case of storage or stop of operation to prevent the paste from being discharged from the container, and opening in case of loading the body  11  on the paste printer (not shown) to dispense a fixed amount of the paste. 
         [0033]    Since the cap  12  opens/closes the supply hole  11   b  in the center of the bottom of the body  11 , the bottom of the body  11  is required to be flat even if the supply hole  11   b  in the body  11  is closed for convenience of use and storage. 
         [0034]    Therefore, the bottom of the body  11  is curved inwardly to form a recessed portion  13  as shown in  FIGS. 4 and 5 , or an annular rim  14  is projected from the bottom of the body  11  as shown in  FIG. 7  and the cap  12  closes the supply hole  11   b.    
         [0035]    According to this, even if the supply hole  11   b  is closed with the cap  12 , the cap  12  does not project beyond a bottom surface of the body  11  (a surface in contact with the top surface of a storage container or table). 
         [0036]    Though the cap  12  which closes the supply hole  11   b  may be simple one, it is preferable that the cap  12  has a connection piece  15  formed as one unit fastened to a bottom surface of the body  11  for preventing the cap  12  from losing for closing the supply hole  11   b  again when the paste filled in the body  11  is not used at a time. 
         [0037]      FIGS. 4 and 5 , which illustrate an embodiment of the present invention, show an example in which one end of the connection piece  15  fastened to the bottom surface of the body  11 . 
         [0038]    If a boss  16  having a holding hole  16   a  is formed on the recessed portion  13  of the body  11 , a ball  17  is formed on the connection piece  15 , which will be placed in the holding hole  16   a , and the ball  17  is pressed fit in the holding hole  16   a  to make the ball  17  deformed and inserted in the holding hole  16   a  without requiring separate jig, the cap  12  can become movable around the ball  17 . 
         [0039]    There is a press member  18  movably mounted in the body  11 , and includes a flange  18   a , a rim  18   b , a sloped portion  18   c  and a deforming portion  18   d  both continuous from the rim  18   b  inwardly, for serving as a cover in storage and transportation and moving inwardly by a pressing force of a pusher  19  in a state the container is loaded on the paste printer. In this instance, the rim  18   b  is in close contact with an inside circumference of the body  11  for the press member to serve as a piston. 
         [0040]    Since a material of the press member  18  will be selected such that the press member  18  enables to serve as a cover in storage and transportation and to serve as the piston as the member  18  is deformed by the pressing force of a pusher  19 , the material of the press member  18  will not be defined. 
         [0041]      FIG. 6  illustrates a cross sectional view of a pressing member in accordance with an embodiment of the present invention. 
         [0042]    Referring to  FIG. 6 , a structure of the pressing member  18  enables a rim  18   b  to make close contact with an inside circumferential surface of the body  11  even without a flange. This type of press member  18  also is adequate to serve as a cover in a general state and serves as a piston in a process the paste  3  is supplied, automatically. 
         [0043]    It is preferable that an angle between the rim  18   b  and the sloped portion  18   c  of the press member  18  is 30˜40°. 
         [0044]    If the angle between the rim  18   b  and the sloped portion  18   c  is smaller than 30°, deformation of a portion in contact with the inside circumferential surface of the body  11  becomes greater in a process the press member  18  is pressed down and deformed by the pusher  19 , to make the press member  18  to fail secure pressing down of the paste, leaving the paste  3  on the inside circumferential surface of the body  11 , and permitting leaking of the paste  3  between the inside circumferential surface of the body  11  and a contact surface of the press member  18  if severe. 
         [0045]    If the angle between the rim  18   b  and the sloped portion  18   c  is greater than 40°, while deformation of the portion in contact with the inside circumferential surface of the body  11  is small in a process the press member  18  is pressed down and deformed by the pusher  19 , because a diameter of the supply hole  11   b  through which the paste  3  is discharged following the pressing down of the pusher  19  on the press member  18  is small to exert a high pressure to the inside of the body  11 , to break or deform the body  11 , it is preferable that the angle of the sloped portion is 30˜40°. 
         [0046]    If the recessed portion  13  is formed in the bottom of the body  11 , it is preferable that a bottom surface of the press member  18  has a recessed portion  20  in conformity with the recessed portion  13  in the body  11 . 
         [0047]    This is for full discharge of the paste  3  from the body  11  through the supply hole  11   b  as the bottom of the body  11  and the bottom surface of the press member  18  are in conformity with each other. 
         [0048]    However, referring to  FIG. 7 , which illustrates another embodiment of the present invention, when the bottom of the body  11  is flat owing to formation of the annular ring  14 , it is evident that the recessed portion in the bottom surface of the press member  18  is not required, but the press member  18  has a flat bottom surface, too. 
         [0049]    The operation of the container for automatically dispensing paste in a paste printer according to the present invention will be described. 
         [0050]    Referring to  FIG. 5A , when it is intended to store or transport the paste  3  in the body  11 , the supply hole  11   b  in the bottom of the body  11  is closed with the cap  12 , to prevent the paste  3  from being discharged or from setting caused by contact with air. 
         [0051]    In this state, if it is intended to make automatic dispensing of the paste  3  to the stencil  2  of the paste printer from the body  11 , the body  11  is clamped over the stencil  2  with known clamping means (not shown). 
         [0052]    Then, after removing the cap  12  to open the supply hole  11   b , the ball  17  placed in the holding hole  16   a  in the boss  16  is turned to place the cap  12 , connected to the ball  17  with the connection piece  15 , away from the supply hole  11   b  so that the paste  3  being discharged through the supply hole  11   b  does not interfere with the cap  12 . 
         [0053]    In this instance, since no external force is applied to the press member  18  that closes the opening  11   a , the press member  18  serves as a cover. 
         [0054]    In this state, if the pusher  19  is moved down by a predetermined stroke with a cylinder (not shown) for automatic supply of the paste  3  to the upper surface of the stencil  2  from the body  11 , because the deforming portion  18   d  of the press member  18  is deformed by the pressing force of the pusher to deform and move down the flange  18   a  of the press member  18 , covering the body, into the body  11  as shown in  FIG. 5B , the rim  18   b  is brought into close contact with the inside circumferential surface of the body  11 , forming a shape similar to a piston. 
         [0055]    In case of the press member  18  shown in  FIG. 6  as another embodiment of the present invention, when the pusher  19  pushes a central portion of the press member  18 , the rim  18   b  is deformed outwardly such that a point the rim  18   b  and the sloped portion  18   c  meets, i.e., a portion of the rim  18   b  that meets with the inside circumferential surface of the body, makes close contact with the inside circumferential surface of the body. 
         [0056]    Along with this, if the press member  18  moves down by a predetermined stroke owing to the pressing force of the pusher  19 , the paste  3  is supplied from the body  11  to the upper surface of the stencil  2  by a fixed amount through the supply hole  11   b  in the bottom of the body  11 . 
         [0057]    The amount of the paste  3  can be fixed by adjusting the stroke of the press member  18  which moves down by the pressing force of the pusher  19 . 
         [0058]    When it is intended to stop the supply of the paste  3  for a time period due to maintenance of the printer or finish of the printing in the middle of accurate dispensing of the paste  3  to the upper surface of the stencil  2  according to above operation, if the supply hole  11   b  is closed with the cap  12 , setting of the paste  3  in the body  11  is prevented as the press member  18  which serves as the piston closes the opening  11   a  of the body  11 . 
         [0059]    It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. 
         [0060]    The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.