Abstract:
A high frequency connector, said connector comprising: an insulating body and a plurality of contacts; the insulating body having an inserting portion, a leading portion, and a plurality of slots disposed between the inserting portion and the leading portion for arranging the contacts, said contacts including first contacts and second contacts, and the first contacts being arranged in staggered pattern with the second contacts, wherein the differential characteristic impedance (Zdiff) of the contacts is around 100Ω±15% to improve the whole transmission efficiency.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a high frequency connector, more particularly, relates to a high frequency board end connector having contacts satisfied a condition of the differential characteristic impedance value (Zdiff) between 100Ω±15%. 
         [0003]    2. Description of the Related Art 
         [0004]    Normally, at least a board end electrical connector is disposed on a circuit board or other board end interface for providing at least a cable end electrical connector to connect an external system by a cable. Said board end electrical connector comprising a plurality of contacts and said cable end electrical connector comprising a plurality of corresponding contacts are touched electrically respectively, when the cable end electrical connector is connected to the board end electrical connector therein. 
         [0005]    In high frequency transmission system, the impedance matching between each of transmission pairs having two transmission lines is a very important control variable for maintaining the quality of high speed transmission, that is, the intervals between each of the transmission pairs should be equal as well as possible, in order to balance the electromagnetic interference effect therebetween. 
         [0006]    However, the contacts are designed in different length corresponding to different configuration on a circuit board.  FIG. 1  is the side view of the configuration of two contacts A 1 , A 2  in a traditional electrical connector. Said contacts A 1 , A 2  are configured in a plurality of solder pads on two different array of a circuit board respectively, wherein the contacts A 1  are interposed between each of the contacts A 2 . Therefore, said contacts A 1 , A 2  will generate a staggered distance in section B thereof while they are connected to a circuit board C respectively, for this reason, its impedance won&#39;t be able to maintain a equal distance matching. Furthermore, while the interval (pitch) between those two contacts is increased slightly, said impedance will be too big caused the block in transmission. 
         [0007]    It is thus desirable to provide an electrical connector satisfied the requirements of ideal differential characteristic impedance which can resolve above problem in prior art. 
       SUMMARY OF THE INVENTION 
       [0008]    The object of the present invention is to provide a high frequency connector with excellent impedance characteristic, thus to improve the overall transmission efficiency. 
         [0009]    In order to achieve the aforementioned object, the present invention is to provide a plurality of contacts fixed in slots of an electrical connector to touch electrically with a plurality of contacts of a corresponding electrical connector respectively. Said contacts form a plurality of transmission paths respectively, and, the distance of each of two transmission paths are equal between the inserting portion and the leading portion, to obtain excellent differential impedance matching. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is the side view of the inserting portion of a traditional electrical connector configured in a staggered layout; 
           [0011]      FIG. 2  is the outlook of the embodiment in accordance with the present invention; 
           [0012]      FIG. 2A  is the exploded view of the embodiment in accordance with the present invention; 
           [0013]      FIG. 3  is the outlook of the inserting portion of the embodiment in accordance with the present invention; 
           [0014]      FIG. 4A  is the first contact of the embodiment in accordance with the present invention; 
           [0015]      FIG. 4B  is the second contact of the embodiment in accordance with the present invention; 
           [0016]      FIG. 5  is the top view of the embodiment in accordance with the present invention; 
           [0017]      FIG. 6  is the bottom view of the embodiment in accordance with the present invention; 
           [0018]      FIG. 7  is the illustrative diagram of the configuration between the first contact and the second contact of the embodiment in accordance with the present invention; 
           [0019]      FIG. 8  is the illustrative diagram of the comparison between the configuration of the traditional contact and the configuration of the first and the second contact of the embodiment in accordance with the present invention; and 
           [0020]      FIG. 9  shows the testing results of the present invention and the traditional connector. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]      FIG. 2  is the outlook of the embodiment in accordance with the present invention. The present invention is an electrical connector  10  fixed on an electronic device  40 , said electrical connector  10  comprising an insulating body  20  and a plurality of contacts  30 , wherein said insulating body  20  includes an inserting portion  21 , a leading portion  22  and a plurality of slots  23  which are passing between said inserting portion  21  and said leading portion  22 . Further, all of the contacts  30  are conductors. Said contacts  30  were inserted between the inserting portion  21  and the leading portion  220  and the contacts were defined at least a ground contact (G) to separate each pair of signal contacts (S+, S−) in equal distance (As shown in  FIG. 3 ). 
         [0022]    As shown in  FIGS. 5 and 6 , wherein the leading portion  22  comprises a first connection points array  221  and a second connection points array  222 . Said connection points arrays include a ground contact (G) and two adjacent signal contacts (S+, S−), and, said ground contact (G) and said signal contacts (S+, S−) are arranged in staggered pattern between the first connection points array  221  and the second connection points array  222 . Furthermore, the location of said ground contact (G) is disposed in the middle of those two adjacent signal contacts (S+, S−). 
         [0023]    As shown in  FIGS. 4A and 4B , said contacts  30  include a plurality of first contacts  31  located in each of the first connection points array  221  and a plurality of second contacts  32  located in each of the second connection points array  222  respectively, that is each of said second contacts  32  interposed between each of said first contacts  31  at different point array on leading portion  22 . 
         [0024]    Each of the first contacts  31  comprises a base  311  fixed inside each of said slots  23 , a bending portion  312  bent downwardly from one end of the base  311 , a tail portion  313  extended downwardly from the bending portion  312 , and a contacting portion  314  formed on the other end of the base  311 . The contacting portion  314  is fixed on the inserting portion  21  of the insulating body  20  for contacting electrically with each of the contacts of the corresponding connector, and, the tail portion  313  is electrically connected to a electronic device  40  by the slot 3   23  of the leading portion  22  (as shown in  FIG. 7 ). 
         [0025]    Each of the second contacts  32  comprises a base  321  fixed within the slots  23 , a first bending portion  322  bent downwardly from one end of the base  321 , a second bending portion  323  bent forwardly from the lower end of the first bending portion  322 , a third bending portion  324  bent downwardly from the outer end of the second bending portion  323 , a tail portion  325  extended downwardly from the third bending portion  324  for connecting with an electronic device  40  electrically, and a contacting portion  326  formed on the other end of the base  321 , wherein a horizontal portion  329  was formed between the second bending portion  323  and the third bending portion  324 . The contacting portion  326  is also fixed on the inserting portion  21  of the insulating body  20  for contacting electrically with each of the contacts of the corresponding connector. 
         [0026]    In general, the electronic device is a circuit board having a plurality of solder pads  41  arranged thereon. Each of solder pads  41  form a hole  42  to permit each tail portion  313  of the first contacts  31  and each tail portion  325  of the second contacts  32  to be inserted therein, and the solder pads  41  form a plurality of signal or ground path to permit the first contacts  31  or the second contacts  32  to be welded on each of the solder pads  41  by the leading portion  22  respectively. 
         [0027]    The ideal differential characteristic impedance (Zdiff) of contacts  30  is satisfied between 100Ω±15%. The contacts forming each of the transmission paths between the inserting portion  21  and each of the solder pads  41  on the electronic device  40  are equal in order to achieve impedance matching therebetween, that is, a plurality of the first contacts  31  form the first transmission paths between each of the solder pads  41  of the electronic device  40  and the first connection points array  221 ; and a plurality of second contacts  32  form the second transmission paths between the second connection points array  222  and the electronic device  40 . 
         [0028]    As shown in  FIGS. 6 and 7 , each of the first transmission paths and each of the second transmission paths are spaced in equal distance one another, that is, the height (h) between the horizontal portion  329  of the second contact  32  and the electronic device  40  is almost equal to the space (s′) between the solder pads  41  of said electronic device  40 . 
         [0029]    Normally, the parameters that affect the differential characteristic impedance include: width (w) of conductor, space (s) between two conductors, thickness (t) of conductor and dielectric constant (∈r), etc. The formulae are shown as follows: 
         [0000]    
       
         
           
             
               
                 
                   Zo 
                   = 
                   
                     
                       60 
                       
                         
                           
                             0.475 
                              
                             ɛ 
                              
                             
                                 
                             
                              
                             r 
                           
                           + 
                           0.67 
                         
                       
                     
                      
                     
                       ln 
                        
                       
                         ( 
                         
                           
                             4 
                              
                             h 
                           
                           
                             0.67 
                              
                             
                               ( 
                               
                                 
                                   0.8 
                                    
                                   w 
                                 
                                 + 
                                 t 
                               
                               ) 
                             
                           
                         
                         ) 
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   1 
                 
               
             
             
               
                 
                   Zdiff 
                   = 
                   
                     2 
                      
                     
                       Zo 
                        
                       
                         ( 
                         
                           1 
                           - 
                           
                             0.48 
                              
                             
                                
                               
                                 
                                   - 
                                   0.96 
                                 
                                  
                                 
                                   5 
                                   8 
                                 
                               
                             
                           
                         
                         ) 
                       
                     
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   2 
                 
               
             
           
         
       
     
         [0030]    According to the above equations, the width (w) of conductor of the contact is in inverse proportion to the value of the differential characteristic impedance (Zdiff). That is, when the width (w) of both sides of each first contact  31  or each second contact  32  increases, the value of the differential characteristic impedance (Zdiff) decreases. On the contrary, while the width (w) decreases, the value of differential characteristic impedance (Zdiff) increases. Therefore, when the width (w) of conductor and the space (s) of two conductors are constant (suppose the value of differential characteristic impedance is within a ideal range between 100Ω±10%), and the pitch (p) of two contacts is 1.27 mm (p□2×w/2+s□ the amount of the width of each conductor add to the space of two conductors), wherein if the pitch (p) is a constant, the space (s) will increases when the width (w) decreases. As shown in  FIG. 8 , the deposition of the contacts of the present invention is different from that of a prior art, so, we can measure the value of differential characteristic impedance (Zdiff) of the present invention (F 1 ) and that of the prior art (F 2 ) by a Time Domain Reflectometry (TDR). 
         [0031]    From the testing results (as shown in  FIG. 9 ), we can find the differential characteristic impedance (Zdiff) of the prior art (F 2 ) is around 133.16820. Obviously, it has exceeded the limitation of differential characteristic impedance (Zdiff) of 100Ω±15%. While in the present invention (F 1 ), the testing result of the differential characteristic impedance (Zdiff) is around 107.33220. That is, the width (w) of both sides of the contacts is between 0.71-0.97 mm, and the space (s) of two contacts is 0.3-0.56 mm, which will satisfy the condition that the space between any central point of two contacts is 1.27 mm and the differential characteristic impedance (Zdiff) is between 100Ω±15%. Further, theoretically, the dimension error of the height (h) between the horizontal portion  329  of the second contacts and the electronic device and the space (s′) between two solder pads (s′) is within ±15%, the differential characteristic impedance will be in an ideal range. While the present invention has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from its scope. Therefore, it is intended that the present invention not be limited to the particular embodiment disclosed, but that the present invention will include all embodiments falling within the scope of the appended claims.