Abstract:
An electrical system includes a first substrate having a first contact portion thereon and a second substrate having a second contact portion thereon. An electrical connector is arranged between the first and second substrates for establishing electrical connection therebetween. The electrical connector includes a plurality of wafer stacked together and each wafer includes at least a passageway defined therein having ends facing the first and second substrates. Each passageway has a terminal moveably supported therein and has end contacting portions electrically contacting with first and second contact portions of said first and second substrates. The terminal includes an arm abutting against an inner side of the passageway.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an electrical connector, and more particularly to an electrical connector configured by wafers including moveable contacts thereby featuring simple, reliable connections. 
     DESCRIPTION OF THE PRIOR ART 
     Making an electrical connector by means of wafers has been known to the industry. However, all contacts are fixedly and securely attached to a wafer, typically as disclosed as below. 
     U.S. Pat. No. 5,993,259 issued to Stokoe et al discloses an electrical connector of such application. The connector disclosed in the &#39;259 patent includes a plurality of modularized wafers bounded together. As shown in FIG. 4 of the &#39;259 patent, the terminals are stamped from a metal sheet, then embedded within an insulative material to form the wafer. 
     U.S. Pat No. 6,083,047 issued to Paagman discloses an approach to make a high-density connector by introducing the use of printed circuit board. According to teaching of the &#39;047 patent, conductive traces are formed on surfaces of the printed circuit board in a mirror-image arrangement, typically shown in FIG. 12. 
     As known to the skilled in the art, electrical connection between two terminals is generally facilitated by normal force exerted from one terminal to the other. However, since surface of the terminal could be contaminated by dust or oxidation, it is preferable to generate a wiping displacement between two terminals during mating. With the wiping displacement between the terminals, dust or oxidation on the terminal could be wiped out, thereby ensuring reliable electrical connection between two mated terminals. 
     The suggestions disclosed above have solder tails soldered to the printed circuit board, while connecting portions make connection through wiping. 
     In addition, since the terminals are fixedly embedded to the wafer, normal force provided by the terminals is then fixed. 
     Another problem of the prior art is that during the engagement of the terminals and the printed circuit board, there is a possibility of collapse of the terminals because an end of the terminal is soldered to the printed circuit board, especially to the terminals with tiny configuration and dimension. In addition, conventional arrangement of the terminal is always parallel to direction of the inserted printed circuit board. 
     Co-pending U.S. patent application entitled to “Electrical Connector”, commonly assigned to the same assignee and filed on May 15, 2001, Ser. No. 09/858,841, discloses an electrical connector having terminals moveably mounted on terminal supports. The specification is attached as for reference. 
     SUMMARY OF THE INVENTION 
     It is an objective of this invention to provide an electrical connector configured by a plurality of wafers. The number of wafers can be increased accordingly to meet different applications. 
     Another objective of this invention is to provide a wafer in which terminals are dynamically received within passageways thereof thereby properly avoiding collapse of the terminals by movement of the terminal within the passageway. 
     In order to achieve to the objectives set forth, an electrical system in accordance with the present invention includes a first substrate having a first contact portion thereon and a second substrate having a second contact portion thereon. An electrical connector is arranged between the first and second substrates for establishing electrical connection therebetween. The electrical connector includes a plurality of wafer stacked together and each wafer includes at least a passageway defined therein having ends facing the first and second substrates. Each passageway has a terminal moveably supported therein and has end contacting portions electrically contacting with the first and the second contact portions of said first and second substrates. The terminal includes an arm abutting against an inner side of the passageway. 
    
    
     SUMMARY OF THE DRAWINGS 
     Other objectives and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a front view of a wafer in accordance with the present invention before a daughter is inserted; 
     FIG. 2 is similar to FIG. 1 with the daughter card inserted; 
     FIG. 3 is a perspective view of a connector configured by sixteen wafers of FIG. 1; 
     FIG. 4 is a bottom view of FIG. 3; 
     FIGS. 5A to  5 C are illustrations showing the daughter card is electrically connected to the motherboard via the connector in accordance with the present invention; 
     FIG. 6 is a bottom view of a wafer in accordance with a second embodiment of the present invention; and 
     FIG. 7 is a front view of FIG.  6 . 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 and 2, a wafer  10  in accordance with the present invention comprises a base portion  11 , of a desired thickness, having a card receiving passageway  12  extending from a top surface  11   a  thereof. The base portion  11  further defines first and second passageways  13 , and  14 , symmetrically arranged with respect to the card receiving passageway  12  and in to a bottom surface  11   b  of the base portion  11 . The base portion  11  further defines a recess  19  extending upward from the bottom surface  11   b  and merging with end portions  13   a ,  14   a  of the passageways  13 ,  14 . 
     First and second terminals  21 ,  22  are received in the passageways  13 ,  14 , respectively. The terminal  21  ( 22 ) includes a base portion  21   a  ( 22   a ), first and second contact portions  21   b ,  21   c  ( 22   b ,  22   c ). Each terminal  21  ( 22 ) further includes an arm  21   d  ( 22   d ) extending from the base portion  21   a  ( 22   a ), respectively. The length of the terminal  21  ( 22 ) is arranged longer than the length of the passageway  13  ( 14 ). As it can be readily seen from FIG. 1, the first contact portion  21   b  ( 2   b ) of the terminal  21  ( 22 ) extends into the recess  19  and flush to the bottom surface  11   b , while the second contact portion  21   c  ( 22   c ) extends into the card receiving passageway  12 . 
     In practice, the bottom surface  11   b  is rested on a mother board  31  (FIGS. 5A to  5 C) on which conductive pads  32 ,  33  are provided. When the wafer  10  is securely mounted onto the motherboard  31 , the first contact portions  21   b ,  22   b  are in contact with the conductive pads  32 ,  33  respectively, while the second contact portion  21   c ,  22   c  extend into the card receiving passageway  12 . 
     When a daughter card  35  having conductive pads  36 ,  37  thereon is inserted into the card receiving passageway  12  and in contact with the second contact portions  21   c ,  22   c , the terminals  21 ,  22  are forced to move along the passageways  13 ,  14 , respectively, such that the first contact portions  21   b ,  22   b  wipe over the conductive pads  32 ,  33 . In addition, since the second contact portions  21   c ,  22   c  are driven into the passageways  13 ,  14 , the second contact portions  21   c ,  22   c  wipe over the conductive pads  36 ,  37 , respectively. Accordingly, reliably electrical connections between the contact portions  21   b ,  22   b ,  21   c , and  22   c  and the conductive pads  32 ,  33 ,  36 , and  37  are achieved. 
     In addition to the wiping motion occurring between the first and second contact portions  21   b ,  22   b ,  21   c , and  22   c  and the conductive pads  32 ,  33 ,  36  and  37 , dynamic motion of the terminals  21 ,  22  within the passageways  13 ,  14  can also effectively reduce the possibility of the collapse of the terminals  21 ,  22  during the engagement with the daughter card  35 . As shown in FIG. 1, prior to the engagement, the base portion  21   a ,  22   a  of the terminals  21 ,  22  are straight. During the engagement, the base portion  21   a  deforms such that the first contact portions  21   b ,  22   b  wipes over the conductive pads  32 ,  33  thereby preventing terminals  21 ,  22  from stubbing and yielding, as shown in FIG.  2 . Without this dynamic motion and subsequent wiping action of the first contact portions  21   b ,  22   b  with respect to the conductive pads  32 ,  33 , it is possible that the terminals  21 ,  22  may stub, yield and collapse. In addition, the provision of the arms  21   d ,  22   d  will also force the base portion  21   a ,  22   a  back to its original position once the daughter card  35  is withdrawn from the card receiving passageway  12 . This results in excellent mechanical performance even though the size of the terminals  21 ,  22  can be quite small. 
     In addition, since the passageways  13 ,  14  are in slant arrangement and the terminals  21 ,  22  are obliquely supported in the passageways  13 ,  14 , , the first contact portions  21   b ,  22   b  contact the conductive pads  32 ,  33  angularly. Accordingly, the wiping motion of the first contact portions  21   b ,  22   b  with respect to the conductive pads  32 ,  33  occurs without causing excess stress to the terminals  21 ,  22  thereby properly avoiding permanent deformation of the terminals  21 ,  22 . 
     Furthermore, the provision of the recess  19  release the extension of the first contact portions  21   b ,  22   b  of the terminals  21 ,  22 . As the second contact portions  21   c ,  22   c  of the terminals  21 ,  22  displace normal to the daughter card they retreat into the passageways  13 ,  14  while engaging with the daughter card  35 . This forces the first contact portions  21   b ,  22   b  to extend into the recess  19 . Without the provision of the recess  19 , the wiping motion is limited to a short distance, while with the provision of the wiping movement, the wiping movement of the contact portions  21   b ,  22   b  can be properly extended. However, the recess  19  can also be replaced by an enlarged portion of each passageways  13 ,  14 . 
     In the above described embodiment, the passageways  13 ,  14  are arranged in the same plane, while in a second embodiment, the passageways  113 ,  114  can be arranged oppositely on first and second surfaces  110   a ,  110   b  of a wafer  110  according to a second embodiment of the present invention. Each passageway  113  ( 114 ) is provided with an enlarged portion  113   a  ( 114   a ) for extension of contact portions  121   b  ( 122   b ) of the terminals  121  ( 122 ), as clearly shown in FIGS. 6 and 7. The terminals  21 ,  22  assembled therein are same as the first embodiment. The wafer  110  also defines a card receiving passageway  112  for receiving a daughter card therein. 
     FIGS. 3 and 4 are views showing a connector  1  configured by sixteen wafers  10  disclosed above. As it can be readily seen, the wafer  10  is defined with holes  16 . When the wafers  10  are assembled, a fastening device (not shown) can extend through to each hole to securely attach the wafers  10  together. Similarly, many external geometric shapes attached to each wafer would provide alternative methods of attaching the wafers  10  together. 
     FIGS. 5A to  5 C detailedly illustrate how the daughter card  35  is electrically connected to a motherboard  31  by the connector  1  disclosed above. 
     It can be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.