Patent Publication Number: US-2006017146-A1

Title: IC with stably mounted chip

Description:
FIELD OF THE INVENTION  
      The present invention relates to an IC with stably mounted chip, and more particularly to an IC having a stably mounted chip and a reduced overall thickness, and allowing an additional chip to stack on the first chip.  
     BACKGROUND OF THE INVENTION  
      A conventional IC, as shown in  FIG. 5 , includes a chip  10  and a leadframe  20  located some distance lower than the chip  10 . The leadframe  20  includes a plurality of leads  201  made of a sheet material and arranged at two opposite sides of the leadframe  20  for electrically connecting the chip  10  to external elements. The leads  201  are connected to contacts on the chip  10  via a metal wire  30 , which may be a golden wire. The chip  10  is usually enclosed by an encapsulating compound  40  to complete the IC. In the above-described IC packaging structure, since the leads  201  are bent in configuration, the completed IC has an increased thickness that does not meet the compactness requirement of the current electronic products.  
       FIG. 6  is a sectional view showing the packaging structure of another conventional IC. In the second conventional IC, there is a leadframe  20 ′ having a plurality of leads  201 ′ in the form of a block each. The leads  201 ′ are fixedly adhered to a lower surface of a chip  10 ′ via an adhesive tape  202 ′ each. After the leads  201 ′ are connected to contacts on the chip  10 ′ via a metal wire  30 ′ each, the chip  10 ′ is enclosed in an encapsulating compound  40 ′ to complete the IC. The second conventional IC has a somewhat reduced overall thickness. However, since the chip  10 ′ is still located above the leads  201 ′, the thickness of the completed IC is still large. Moreover, since there is only one chip  10 ′ mounted in the IC in a manner not so stable to ensure a high processing and storing efficiency or to provide multiple functions, the IC does not satisfy the requirement of current electronic products.  
     SUMMARY OF THE INVENTION  
      A primary object of the present invention is to provide an IC having a structure allowing at least one chip to stably mount therein and reduction of an overall thickness of the IC.  
      Another object of the present invention is to provide an IC having a structure allowing two chips to stably stack therein to enable high processing and storing efficiency and multiple functions.  
      To achieve the above and other objects, the IC with stably mounted chip according to the present invention includes a chip, a leadframe, a bridge, and an encapsulating compound. The bridge is a flat arch made of a sheet material and includes a horizontal fixing section and a supporting section downward extended from each end of the fixing section. The chip is adhered to a bottom side of the fixing section of the bridge. The leadframe includes a plurality of leads arranged at two opposite sides of the chip. The encapsulating compound is applied to cover the chip, the bridge, and inner portions of the leads to complete a compact IC having a stably mounted chip and a reduced overall thickness. And, an additional chip may be adhered to a top of the bridge, so that two chips are stably stacked in the IC. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein  
       FIG. 1  is a top plan view showing the packaging structure of an IC according to a first embodiment of the present invention;  
       FIG. 2  is a sectioned front view of the IC of  FIG. 1 ;  
       FIG. 3  is a sectioned side view of the IC of  FIG. 1 ;  
       FIG. 4  is a sectioned front view of an IC according to a second embodiment of the present invention;  
       FIG. 5  is a sectional view showing the packaging structure of a conventional IC; and  
       FIG. 6  is a sectional view showing the packaging structure of another conventional IC. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Please refer to  FIG. 1  that is a top plan view showing the packaging structure of an IC with stably mounted chip according to a first embodiment of the present invention. As shown, the IC includes a chip  1 , a leadframe  2 , a bridge  3 , and an encapsulating compound  4 .  
      Please refer to  FIGS. 1, 2 , and  3  at the same time. The chip  1  is a product formed by known techniques and is therefore not described in details herein. The leadframe  2  includes a plurality of leads  21  arranged at two opposite lateral sides or all four sides of the leadframe  2  to electrically connect to external elements. Each of the leads  21  includes an outer and an inner electrical connecting end  211 ,  212 . The encapsulating compound  4  is an insulating material covering the chip  1  and the inner electrical connecting ends  212  of the leadframe  2 . The bridge  3  is a flat arch or an inverted U-shaped member made of a sheet material, and includes a supporting section  31  downward extended from each end of a horizontal fixing section  32 . The chip  1  is adhered to a bottom side of the fixing section  32  of the bridge  3  via an adhesive layer  5 . In the illustrated first embodiment, the leads  21  of the leadframe  2  are arranged at two opposite lateral sides of the chip  1  and electrically connected at the inner electrical connecting ends  212  to the chip  1  via a metal wire  6  each. After the encapsulating compound  4  is applied to enclose the chip  1 , the chip  1  is stably mounted in the encapsulating compound  4  to complete the IC of the present invention.  
      Since the chip  1  is fixedly adhered to the bottom side of the bridge  3  before being packaged with the leadframe  2 , the chip  1  is stably positioned and well protected during and after the packaging of the IC. Moreover, since the leads  21  arranged at two or four sides of the leadframe  2  are located at lateral outer sides of the chip  1 , allowing the chip  1  to locate at a lower position. In this manner, the completed IC with the chip  1  enclosed in the encapsulating compound  4  has a reduced overall thickness to meet the compactness requirement of current electronic products.  
       FIG. 4  is a sectioned front view of an IC with stably mounted chip according to a second embodiment of the present invention. The second embodiment is generally structurally similar to the first embodiment, except that an additional chip  1 ′ is adhered to a top of the fixing section  32  of the bridge  3 . Therefore, the IC of the present invention may include two stably stacked chips  1 ,  1 ′ to enable high processing and storing efficiency as well as multiple functions thereof.