Patent Publication Number: US-2007113717-A1

Title: Cutting fixture for printed circuit board mounted with electronic components

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a cutting fixture for printed circuit boards, and more particularly to a cutting fixture for printed circuit boards mounted with electronic components.  
      2. Description of Related Art  
      With rapid development of the science and technology, along with rapidly increasing demands for electronic products with multiple functions, modular designs and modular fabrication processes for printed circuit boards have become a mainstream on account of factors such as the economic efficiency and the production cost.  
      In a conventional modular fabrication process for printed circuit boards, a plurality of printed circuit board units is first defined on a whole piece of printed circuit board module. Then, a plurality of circuit structures is formed on the whole piece of printed circuit board module corresponding to the printed circuit board units such that electronic components such as semiconductor chips or other active and passive components can be mounted to the printed circuit board units. Finally, the whole piece of printed circuit board module is fixed to a cutting fixture and a cutting tool is used to cut the whole piece between the printed circuit board units. Thus, the whole piece of printed circuit board module is cut into a plurality of printed circuit boards mounted with electronic components.  
       FIG. 1  is a conventional cutting fixture for a printed circuit board. As shown in  FIG. 1 , the cutting fixture has a grid-shaped plate  11  formed thereon. A plurality of positioning holes  110  is formed in the grid-shaped plate  11 . The positioning holes  110  correspond in position to openings formed on the surface of a printed circuit board module to be cut. A plurality of positioning pins  12  are inserted into and fixed to the positioning holes  110 . The printed circuit board module to be cut can then be fixed to the positioning pins  12  through the openings of the printed circuit board module.  
      Although the above positioning pins can be inserted into different positioning holes according to different types of printed circuit board modules, it may take as much as 2 hours to rearrange the positioning pins to make them correspond in position to a new type of printed circuit board modules in practical fabrication processes, thereby adversely affecting the cutting efficiency. In addition, since the distance between the adjacent positioning holes arranged on the grid-shaped plate is certain and can not be changed, it is almost impossible to completely align the positioning pins with the predefined openings of the printed circuit board module, which not only makes it difficult to fix the printed circuit board module to the cutting fixture, but also leads to too loose or too tight engagement between the positioning pins and the openings. Too loose engagement between the positioning pins and the openings causes the printed circuit board module to displace during the cutting process, while too tight engagement between the positioning pins and the openings increases difficulty of detachment of the printed circuit board module from the cutting fixture and causes the printed circuit board module to tilt during the cutting process. Displacing and tilting of the printed circuit board module are easy to introduce the cutting error during the cutting process, which adversely affects the cutting quality.  
     SUMMARY OF THE INVENTION  
      According to the above defects, an objective of the present invention is to provide a cutting fixture for a printed circuit board mounted with electronic components, which can effectively fix the printed circuit board to the cutting fixture so as to prevent the displacement of the cutting position of the printed circuit board.  
      Another objective of the present invention is to provide a cutting fixture for a printed circuit board mounted with electronic components, through which a printed circuit board mounted with electronic components can be easily attached to or detached from the cutting fixture, thereby increasing the cutting efficiency.  
      A further objective of the present invention is to provide a cutting fixture for a printed circuit board mounted with electronic components, which can efficiently prevent cutting errors, thereby increasing the production yield.  
      To achieve the above and other objectives, the present invention discloses a cutting fixture for a printed circuit board mounted with electronic components. The cutting fixture comprises: a base; and a replaceable cover plate mounted on the base, wherein, the cover plate comprises openings for receiving the electronic components of the printed circuit board, cutting through holes for allowing a cutting tool to pass through, guide blocks for engaging lateral sides of the printed circuit board, and positioning posts for fixing the printed circuit board to the cover plate.  
      The cover plate can be secured to the base by screws and changed to adapt the cutting fixture to different types of printed circuit boards.  
      The openings of the cover plate can respectively receive the electronic components disposed on and extending away from the surface of the printed circuit board. Meanwhile, the size of the openings can be changed according to that of the corresponding electronic components.  
      The cutting through holes of the cover plate allow the cutting tool to be inserted therein such that the cutting tool can cut the printed circuit board along a predefined cutting line.  
      The guide blocks of the cover plate are disposed on lateral sides of the cover plate so as to abut against the printed circuit board. Oblique surfaces can be respectively formed on inner sides of the guide blocks engaging the printed circuit board such that the printed circuit board can be slid to position. The guide blocks further can fix the leftover materials from the cutting process.  
      The positioning posts are mounted on the cover plate corresponding in position to openings predefined in the printed circuit board so as to fix the printed circuit board to the cover plate.  
      Therefore, through the guide blocks and the positioning posts of the cover plate, a printed circuit board can be quickly and accurately mounted to the cutting fixture and securely and steadily hold by the cutting fixture with the electronic components of the printed circuit board being received in the corresponding openings of the cover plate. The displacing and tilting of the printed circuit board are prevented, the mounting time is reduced, and the cutting efficiency and cutting quality are increased. In addition, since the leftover material is fixed to the cutting fixture, cutting accidents are prevented.  
      Furthermore, in the present invention, to cut a different type of printed circuit board, only the cover plate of the cutting fixture needs to be replaced, thereby saving the cutting fixture assembly time. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       FIG. 1  is a diagram of a conventional printed circuit board cutting fixture; and  
       FIG. 2  is a diagram of a cutting fixture for a printed circuit board mounted with electronic components according to the present invention. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
      Hereunder, embodiments of the present invention will be described in full detail with reference to the accompanying drawings.  
      Referring to  FIG. 2 , a cutting fixture used to hold a printed circuit board mounted with electronic components during a cutting process is shown.  
      As seen in  FIG. 2 , the cutting fixture comprises a base  20   b  and a replaceable cover plate  20   a  mounted on the base  20   b . The base  20   b  and the cover plate  20   a  jointly define a receiving space therebetween. The cover plate  20   a  comprises a plurality of openings  21  for receiving the electronic components of the printed circuit board, a plurality of cutting through holes  22  for allowing a cutting tool to pass through, a plurality of guide blocks  23  for engaging lateral sides of the printed circuit board, and positioning posts  24  for fixing the printed circuit board to the cover plate  20   a.    
      The cover plate  20   a  is detachably secured to the base  20   b  by screws or latching components such that the cover plate  20   a  can be easily replaced according to different types of printed circuit boards. That is, to cut a different type of printed circuit board, a user only needs to mount a corresponding cover plate  20   a  on the base  20   b , which increases the assembly speed of the cutting fixture and accordingly increases the cutting efficiency and cutting quality.  
      The openings  21  of the cover plate  20   a  can receive electronic components disposed on and extending away from the surface of the printed circuit board. The electronic components can be different types of active and passive components such as semiconductor chips, conductor components, resistor components and inductor components. Meanwhile, size of the openings  21  can be changed according to that of the electronic components. The openings  21  can further be divided into openings  211  penetrating through the cover plate  20   a  and openings  212  without penetrating through the cover plate  20   a.    
      The cutting through holes  22  of the cover plate  20   a  allow a cutting tool such as a milling cutter to be inserted therein such that the cutting tool can cut the printed circuit board along a predefined cutting line so as to form a plurality of printed circuit board units.  
      The guide blocks  23  are disposed on lateral sides of the cover plate  20   a  and abut against the printed circuit board mounted to the cover plate  20   a  to prevent the displacement of the printed circuit board. Meanwhile, oblique surfaces can be respectively formed on inner sides of the guide blocks  23  that engage the printed circuit board such that the printed circuit board can be slid along the oblique surfaces into position. Further, the leftover materials from the cutting process can be fixed to the guide blocks  23  to avoid cutting accidents.  
      The positioning posts  24  are disposed on the cover plate  20   a  corresponding in position to openings predefined in the printed circuit board such that the printed circuit board can be fixed to the cover plate  20   a  through the positioning posts  24 .  
      Therefore, the cutting fixture of the present invention mainly comprises a base and a cover plate. The cover plate has a plurality of openings formed therein to receive electronic components mounted on a printed circuit board, a plurality of cutting through holes formed therein to allow a cutting tool to pass through, a plurality of guide blocks disposed thereon to engage lateral sides of the printed circuit board and a plurality of positioning posts disposed thereon to fix the printed circuit board to the cover plate. With the help of the guide blocks and the positioning posts, a printed circuit board can be quickly, accurately and steadily fixed to the cover plate with its electronic components received in the corresponding openings of the cover plate, thereby preventing the printed circuit board from displacing and tilting. As a result, the cutting efficiency and cutting quality are increased, while the assembly time and labor cost are reduced. In addition, since the leftover material is fixed to the cutting fixture, cutting accidents are prevented.  
      Furthermore, the cutting fixture of the present can be adapted to different types of printed circuit boards by changing the cover plate. To cut a different type of printed circuit board, only the cover plate of a cutting fixture needs to be replaced. Hence, the fixture assembly time is reduced and the cutting efficiency and cutting quality are increased.  
      The invention has been described using exemplary preferred embodiments. However, it is to be understood that the scope of the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements. The scope of the claims, therefore, should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.