Abstract:
A package structure that uses a bump posited type lead frame is disclosed. The package structure uses a lead frame having holes thereon for accommodating conductive bumps of a chip or a positioning film having openings thereon for accommodating conductive bumps of a chip or both to avoid the flow and deformation of the conductive bumps during bonding so as to prevent the electrical property of the package structure from degradation and increase the reliability of the chip package.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a lead frame package structure, and more particularly to a package structure module of bump posited type lead frame.  
         [0003]     2. Description of the Related Art  
         [0004]     Owing to the demands and availability of electronic products with multifunction as well as the development of semiconductor technology, the package technologies of advanced commercial semiconductor devices must advance toward simplified processes, minimized structure size, high integration, strengthened electrical connection and high thermal conductivity from conventional package processes, large-size structure and limited electrical characteristics. For lead frame package technologies, conventional lead frame packages which bond a chip having bumps onto a lead frame with pre-plated silver thereon to complete electrical connection and to form a flip chip package structure have several drawbacks. For example, positioning and bonding of the bumps onto the lead frame usually lack accuracy so that the electrical connection and package reliability are degraded and the yield ratio is also decreased. Moreover, even the positioning of the bumps dose not cause any bonding issue, due to the wettability and fluidity of the bumps, the bumps still could be bonded onto the lead frame inaccurately so as to result in the degradation of electrical property of the package structure.  
         [0005]     In view of the drawbacks mentioned with the prior art, there is a continued need to develop new and improved package structure that overcomes the disadvantages associated with prior art. The requirements of this invention are that it solves the problems mentioned above.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006]     It is therefore an object of the invention to provide a package structure with pre-etched holes formed on leads of a lead frame used as bump positioning and bonding to avoid the degradation of electrical property resulting from the dislocations of chip bumps and increase the reliability of the chip package.  
         [0007]     It is another object of this invention to provide a package structure with a positioning film on a lead frame used as bump positioning to avoid the degradation of electrical property resulting from the dislocation of chip bumps and increase the reliability and life time of the chip package.  
         [0008]     It is a further object of this invention to provide a package structure with pre-etched holes formed on leads of a lead frame and a positioning film on the lead frame used as bump positioning and bonding to avoid the degradation of electrical property resulting from the dislocations of chip bumps and increase the reliability and life time of the chip package.  
         [0009]     To achieve these objects, and in accordance with the purpose of the invention, the invention provides a package structure comprising a chip having conductive bumps and a lead frame having holes thereon for accommodating the conductive bumps, the chip bonds to the lead frame via the conductive bumps.  
         [0010]     In one embodiment of the invention, the package structure comprises a chip having conductive bumps and a lead frame, and a positioning film on the lead frame, the chip bonds to the lead frame via the conductive bumps, the positioning film having openings for accommodating the conductive bumps.  
         [0011]     In another embodiment of the invention, the package structure comprises a chip having conductive bumps, a lead frame having holes thereon for accommodating the conductive bumps and a positioning film on the lead frame, the chip bonds to the lead frame via the conductive bumps, the positioning film have openings for accommodating the conductive bumps, each the opening is superimposed on each the hole.  
         [0012]     The invention also provides a lead frame module of a package structure comprising a lead frame comprising leads having holes thereon for accommodating conductive bumps of a chip and a positioning film on the lead frame, the chip bonds to the lead frame via the conductive bumps; the positioning film have openings for accommodating the conductive bumps, each the opening is superimposed on each the hole.  
         [0013]     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The present invention is best understood by reference to the following detailed description when read in conjunction with the accompanying drawings.  
         [0015]      FIG. 1  shows a top view of a package structure;  
         [0016]      FIG. 2A  shows a bottom view of the first embodiment of the package structure;  
         [0017]      FIG. 2B  shows a cross sectional view of the first embodiment of the package structure of the invention;  
         [0018]      FIG. 3A  shows a bottom view of the second embodiment of the package structure;  
         [0019]      FIG. 3B  shows a cross sectional view of the second embodiment of the package structure of the invention;  
         [0020]      FIG. 4A  shows a view of the third embodiment of the package structure;  
         [0021]      FIG. 4B  shows a cross sectional view of the third embodiment of the package structure of the invention;  
         [0022]      FIG. 5A  shows a top view of a corner of the lead frame corresponding to the first and second embodiment of the invention; and  
         [0023]      FIG. 5B and 5C  show a top view and a cross sectional view of only one lead having one hole thereon respectively. 
     
    
       [0024]     Common reference numerals are used throughout the drawings and detailed description to indicate like elements.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0025]     Referring to  FIG. 1 , a top view of a package structure  100  is shown. In this top view of the package structure  100 , a protecting dielectric material  101  and a chip  102  are shown. The protecting dielectric material  101  comprises a molding compound, but other dielectric material can also be used. Based on the package structure  100  shown in  FIGS. 1 , three embodiments of the package structure of the invention are shown in  FIGS. 2A-2B ,  3 A- 3 B and  4 A- 4 B.  
         [0026]     Referring to  FIG. 2A , a bottom view of the first embodiment of the package structure  100  is shown. In this bottom view of the package structure  100 , a lead frame  103  and a positioning film  104  as well as the protecting dielectric material  101  are shown. The lead frame  103  comprises leads  105  and a die attach pad  106 .  FIG. 2B  shows a cross sectional view of the first embodiment of the package structure of the invention. Particularly,  FIG. 2B  shows a cross sectional view of the left portion of the package structure  100  shown in  FIG. 1  and  FIG. 2A . In this embodiment, the chip  102  bonds onto the lead frame  103  via conductive bumps  108 . The leads of the lead frame  103  have holes  110  for positing the bumps  108 . The number and location of the holes  110  on the lead frame  103  depend on the number and position of the bumps  108  of the chip  102 . For example, each hole  110  can be formed on each lead  105 . The positioning film  104  also has openings superimposed on the hole  110  and the openings are used to fix the bumps  108  so as to prevent the bumps  108  from deformation. The protecting dielectric material  101  is formed between the chip  102  and the lead frame  103 . The holes  110  of the lead frame  103  and the openings of the positioning film  104  are used to avoid the flow and deformation of the bumps  108  during bonding so as to prevent the electrical property from degradation and increase the reliability of the chip package.  
         [0027]     Referring to  FIG. 3A , a bottom view of the second embodiment of the package structure  100  is shown. In this bottom view of the package structure  100 , the lead frame  103  and the protecting dielectric material  101  are shown. The lead frame  103  comprises leads  105  and the die attach pad  106 .  FIG. 3B  shows a cross sectional view of the second embodiment of the package structure of the invention.  FIG. 3B  particularly shows a cross sectional view of the left portion of the package structure  100  shown in  FIG. 1  and  FIG. 3A . In this embodiment, the chip  102  bonds onto the lead frame  103  via conductive bumps  108 . The leads of the lead frame  103  have holes  110  for positing the bumps  108 . The number and location of the holes  110  on the lead frame  103  depend on the number and position of the bumps  108  of the chip  102 . For example, each hole  110  can be formed on each lead  105 . The protecting dielectric material  101  is formed between the chip  102  and the lead frame  103 . The holes  110  of the lead frame  103  are used to avoid the flow and deformation of the bumps  108  during bonding so as to prevent the electrical property from degradation and increase the reliability of the chip package.  
         [0028]     Referring to  FIG. 4A , a view of the third embodiment of the package structure  100  is shown. In this view of the package structure  100 , the lead frame  103  and the positioning film  104  are shown while the chip  102  and the protecting dielectric material  101  are not shown. The lead frame  103  comprises leads  105  and the die attach pad  106 .  FIG. 4B  shows a cross sectional view of the third embodiment of the package structure of the invention. Particularly,  FIG. 4B  shows a cross sectional view of the left portion of the package structure  100  shown in  FIG. 1  and  FIG. 4A . In this embodiment, the chip  102  bonds onto the lead frame  103  via conductive bumps  108 . The positioning film  104  has openings superimposed on the lead frame  103  and the openings are used to fix the bumps  108  so as to prevent the bumps  108  from deformation. The number and location of the openings on the positioning film  104  depend on the number and position of the bumps  108  of the chip  102 . The protecting dielectric material  101  is formed between the chip  102  and the lead frame  103 . The openings of the positioning film  104  are used to avoid the flow and deformation of the bumps  108  during bonding so as to prevent the electrical property from degradation and increase the reliability of the chip package.  
         [0029]     Referring to  FIG. 5A , a top view of a corner of the lead frame  103  corresponding to the first and second embodiment of the invention is shown. As shown in  FIG. 5A , each hole  110  is formed on each lead  105 .  FIG. 5B and 5C  show a top view and a cross sectional view of only one lead  105  having one hole  110  thereon respectively.  
         [0030]     This disclosure provides exemplary embodiments of the present invention. The scope of the present invention is not limited by these exemplary embodiments. Numerous variations, whether explicitly provided for by the specification or implied by the specification, such as variations in structure, dimension, type of material and manufacturing process may be implemented by one of skill in the art in view of this disclosure.