Patent Publication Number: US-2005124186-A1

Title: Electronic device having adapter and connection method thereof

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to an electronic device having an adapter, and in particular to an electronic device having an adapter accommodating electronic elements disposed on a circuit board.  
      2. Description of the Related Art  
      In surface mount technology (SMT) the leads of an electronic element are soldered to the surface on which the electronic element is positioned. Hence, no holes are required on the circuit board, enabling placement of electronic elements on both sides thereof. SMT frequently employs ball grid array (BGA) and leadless chip carrier (LCC) technologies.  
      In BGA technology, solder balls are placed between an electronic element (chip) and a circuit board. The circuit board is heated to melt the solder balls. Thereby, the chip is electrically connected to the circuit board. In addition to electrical connection of an electronic element and a circuit board, BGA technology can also be applied to electrical connection of two circuit boards. As shown in  FIG. 1   a , an array of solder balls  14  is placed between a circuit board  10  bearing an electronic element  16  and a circuit board  20 . The circuit board  10  is heated to melt the solder balls  14  to electrically connect the circuit boards  10  and  20 . Signals are thereby transmitted from the circuit board  10  to the circuit board  20 .  
      As shown in  FIG. 1   b , the circuit board  10  further bears another electronic element  18  on the other side thereof, and the height of the electronic element  18  is greater than the diameter of the solder ball  14  making the electrical connection of the circuit board  10  and  20  impossible. Therefore, a connection structure is needed between the circuit boards  10  and  20  when both sides of the circuit board  10  bear electronic elements. (The required electrical connection therebetween is normally made possible by BGA technology.)  
      In addition to BGA technology, leadless chip carrier (LCC) technology can also be applied to electrical connection of the circuit boards  10  and  20 . The main features of LCC technology are shown in  FIG. 1   c . Grooves  120  are defined on one edge of a circuit board  100  and metal pads  140  corresponding to the grooves  120  are disposed on circuit board  20 . Solder is placed on the metal pad  140 . When the circuit boards  100  and  20  are heated, the solder is melted and rises up along the groove  120  due to capillary force until the solder solidifies to complete the electrical connection of the circuit boards  100  and  20 . When the other side of the circuit board  100  bears an electronic element  180 , electrical connection is difficult to achieve with LCC technology, as shown in  FIG. 1   d . Thus, a connection structure is needed to electrically connect the circuit boards  100  and  20 .  
     SUMMARY OF THE INVENTION  
      Accordingly, an object of the invention is to provide an electronic device having an adapter connecting one circuit board provided with electronic elements on both sides thereof to another circuit board.  
      BGA technology or LCC technology can be applied to electrical connection in the invention.  
      The electronic device of the invention comprises a first circuit board, a first electronic element disposed on the first circuit board, a first adapter having a first surface, a second surface and a recess, and a second circuit board, wherein the first adapter is electrically connected to the first and second circuit boards and disposed therebetween, the first electronic element is accommodated by the recess.  
      In BGA technology, the electronic device further comprises a plurality of first solder balls disposed on the first surface and electrically connected to the first circuit board, and a plurality of second solder balls disposed on the second surface and electrically connected to the second circuit board.  
      In LCC technology, a plurality of first grooves are defined on the periphery of the first circuit board and longitudinally extends perpendicular to the first and second circuit boards, and a plurality of second grooves corresponding to the first grooves are defined on the periphery of the first adapter and longitudinally extends perpendicular to the first and second circuit boards.  
      In another aspect, BGA and LCC technology can be combined. Thus, a plurality of first solder balls are disposed on the first surface and electrically connected to the first circuit board, and a plurality of third grooves are defined on peripheral of the first adapter and longitudinally extend perpendicular to the first and second circuit boards.  
      The first adapter may use metal connectors to electrically connect the first and second circuit boards rather than BGA or LCC technology, wherein the first adapter further has a plurality of connectors comprising a first contacting portion, a second contacting portion and a connecting portion. The connecting portion is embedded in the first adapter, the first contacting portion and the second contact portion are protruding over the first adapter to contact the first surface and the second surface respectively. The first contacting portion, the second contacting portion and the connecting portion can be integrally formed.  
      A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein;  
       FIG. 1   a  is a schematic view showing BGA technology applied to electrical connection of circuit boards as referenced in the Related Art;  
       FIG. 1   b  is a schematic view showing BC-A technology inapplicable to a circuit board with electronic elements on both sides;  
       FIG. 1   c  is a schematic view showing LCC technology applied to electrical connection of circuit boards as referenced in the Related Art;  
       FIG. 1   d  is a schematic view showing LCC technology inapplicable to a circuit board with electronic elements on both sides;  
       FIG. 2   a  is a schematic view of the first embodiment of the invention;  
       FIG. 2   b  is a front view of the first embodiment of the invention;  
       FIG. 2   c  is a top view of the first embodiment of the invention;  
       FIG. 3   a  is a schematic view of the second embodiment of the invention;  
       FIG. 3   b  is a front view of the second embodiment of the invention;  
       FIG. 3   c  is a top view of the second embodiment of the invention;  
       FIG. 4   a  is a schematic view of the third embodiment of the invention;  
       FIG. 4   b  is a front view of the third embodiment of the invention;  
       FIG. 4   c  is a top view of the third embodiment of the invention;  
       FIG. 5  is a schematic view of the fourth embodiment of the invention;  
       FIG. 6   a  is a schematic view of the fifth embodiment of the invention;  
       FIG. 6   b  is a perspective view of the fifth embodiment of the invention; and  
       FIG. 6   c  is cross section along A-A line of  FIG. 6   b.   
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     First Embodiment  
      As shown in  FIG. 2   a , a first circuit board  200  bears an electronic element  26  on one side thereof and another electronic element  28  on the other side thereof. The first circuit board  200  is electrically connected to a second circuit board  20  via an adapter  29 , and the electronic element  28  is accommodated in a recess  23  of the adapter  29 .  
      As shown in  FIGS. 2   b  &amp;  2   c , BGA technology is applied. A plurality of solder balls  22  are disposed on one surface of the adapter  29  and a plurality of solder balls  24  are disposed on the other surface of the adapter  29 . Upon assembly, the solder balls  22  contact the first circuit board  200  and the solder balls  24  contact the second circuit board  20 . The solder balls  22 ,  24  are melted to complete the electrical connection of the first circuit board  200 , the adapter  29  and the second circuit board  20 .  
     Second Embodiment  
      As shown  FIG. 3   a , an electronic element  36  is disposed on one side of a first circuit board  300  and an electronic element  38  is disposed on the other side thereof. The first circuit board  300  is electrically connected to a second circuit board  20  via an adapter  39 , and the electronic element  38  is accommodated in a recess  33  of the adapter  39 .  
      LCC technology is applied in this embodiment as shown in  FIGS. 3   b  &amp;  3   c . A plurality of grooves  32  are defined on the periphery of the adapter  39  and a plurality of metal pads  34  corresponding to the grooves  32  are disposed on the first circuit board  300 . Upon assembly, solder is placed on the metal pads  34  and heated to melt. The melted solder rises up along the grooves  32  due to capillary force until the solder solidifies to complete the electrical connection of the is circuit board  300  and the adapter  39 . The electrical connection of the adapter  39  and the second circuit board  20  is completed with the same method. Solder is placed on metal pads (not shown) of the second circuit board  20 , corresponding to the grooves  32  and heated to melt. The melted solder rises up along the grooves  32  until the solder solidifies to complete the electrical connection.  
     Third Embodiment  
      In this embodiment, BGA technology and LCC technology are combined. As shown in  FIG. 4   a , a first circuit board  200  bearing electronic elements  26  and  28  is electrically connected to the second circuit board  20  via an adapter  49  wherein the electronic element  28  is accommodated in a recess  43  of the adapter  49 .  
      As shown  FIGS. 4   b  &amp;  4   c , a plurality of grooves  42  are defined on periphery of the adapter  49 , and a plurality of solder balls  44  are disposed on the adapter  49  and contacts the first circuit board  200 . Thereby, BGA technology is applied to the connection of the first circuit board  200  and the adapter  49  as described in the first embodiment, and LCC technology is applied to the connection of the adapter  49  and the second circuit board  20  as described in the second embodiment.  
     Fourth Embodiment  
      The first circuit board  200  bears electronic elements  26  &amp;  28  on both sides thereof. If an electronic element  52  is disposed on the second circuit board  20  and the first circuit board  200  must be connected to the second circuit board  20  at the position of the electronic element  52 , a connection structure having two adapters is needed.  
      As shown in  FIG. 5 , a first adapter  501  and a second adapter  502  are disposed between the first circuit board  200  and the second circuit board  20 . The electronic element  28  is accommodated in a first recess  5013  of the first adapter  501 , and the electronic element  52  is accommodated in a second recess  5023  of the second adapter  502 . BGA technology is applied in this embodiment. Therefore, a plurality of solder balls  5012  are disposed between the first circuit board  200  and the first adapter  501 , and a plurality of solder balls  5014  are disposed between the first adapter  501  and the second adapter  502 , and a plurality of solder balls  5024  are disposed between the second adapter  502  and the second circuit board  20 . The solder balls  5012 ,  5014  and  5024  are heated and melted to complete the electrical connection of the first circuit board  200  and the second circuit board  20 .  
     Fifth Embodiment  
      As shown in  FIG. 6   a , the first circuit board  200  bears the electronic element  26  on one side thereof and the electronic element  28  on the other side thereof. The first circuit board  200  is electrically connected to the second circuit board  20  via an adapter  69  having a recess  63  in which the electronic element  28  is accommodated.  
       FIG. 6   b  is a perspective view of the adapter  69  of the invention.  FIG. 6   c  is cross section along line A-A in  FIG. 6   b . As shown in  FIG. 6   c , a plurality of connectors  64  are mounted on the adapter  69 . The connector  64  is formed by inserting and bending copper sheet or column into the adapter  69  into a C shape. The connector  64  comprises a first contacting portion  641 , a second contacting portion  642  and a connecting portion  643 . The first contacting portion and the second contact portion are protruding over the adapter  69  to contact the first surface and the second surface respectively. The first contacting portion  641  contacts the first circuit board  200  and the second contacting portion  642  contacts the second circuit board  20 . Solder is placed respectively between the first contacting portion  641  and the first circuit board  200  and between the second contacting portion  642  and the second circuit board  20 . The solder is melted to complete the electrical connection of the first and second circuit boards  200  and  20 .  
      As shown in  FIGS. 6   b  and  6   c , the connectors  64  are staggered around the recess  63 . The arrangement of the connectors  64  and the copper trace on the first and second circuit boards  200  and  20  contribute to the shielding effect on the electronic element  28 .  
      The adapter of the invention connects a circuit board having electronic elements on both sides thereof to another circuit board, which cannot be accomplished by the conventional art. Moreover, in the invention, BGA and LCC technology can be applied to the connection. The metal connectors of the invention further contribute to the shielding effect on the electronic elements accommodated in the recess.  
      While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.