Patent Publication Number: US-2004048523-A1

Title: High elasticity contact for electrical connector and contact carrier

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to contacts used in an electrical connector adapted to connect a printed circuit board (PCB) with an electrical package.  
       [0003] 2. Description of the Prior Art  
       [0004] The size of electrical connectors used in computers is becoming steadily smaller. Such connectors essentially comprise a housing and a plurality of contacts received in the housing. Yet the contacts of the connector need to have long elastically deformable arms, in order to ensure reliable electrical connection between the connector and an electrical package mounted on the connector. A typical such connector is disclosed in Taiwan Patent Publication No. 444960. Referring to FIGS. 6 and 7, the connector comprises a base  8  defining a plurality of passageways  80  adapted to receive corresponding contacts (not shown). Each row of passageways  80  defines a line forming an angle of 45 degrees relative to the sidewall  82  of the connector. This configuration provides each passageway  80  with sufficient space to receive a contact having long elastic arms. However, limited by the present manufacturing technology, this arrangement mode is not appropriate to receive the contacts arrayed in rows or columns correctly at the same time. In addition, as each row of the passageway  80  inclines an angle to the sidewalls  82 , the manufacturing matrix must be designed as the same structure, which obviously increase the difficulty of manufacturing.  
       [0005]FIG. 8 shows a conventional contact  60  for receiving a pin of an electrical package. FIG. 9 shows a plurality of preforms of the contact  60  connected with a carrier strip  70 . The carrier strip  70  is stamped from conductive metallic material, and comprises an operation carrier  66 , a plurality of connecting portions  65  extending from one side of the operation carrier  66 , and a plurality of contacts  60  extending from respective connecting portions  65 . Each contact  60  comprises a medial portion  61 , a solder portion  64  extending from one end of the medial portion  61 , and a spring portion  63  extending from an opposite end of the medial portion  61 . A plurality of barbs  611  is formed on opposite side edges of the medial portion  61 , for interferentially fastening the contact  60  in a corresponding passageway of an electrical connector (not shown). The spring portion  63  is relatively long, providing it with good elasticity. However, in the carrier strip  70 , the spring portions  63  of the performs are parallel to the operation carrier  66 . Thus spaces between preforms are unduly large. This leads to wastage of the conductive metallic material, which increases manufacturing costs.  
       [0006] Hence, a new contact which overcomes the above-described disadvantages is desired.  
       SUMMARY OF THE INVENTION  
       [0007] An object of the present invention is to provide an electrical contact which has high elasticity.  
       [0008] Another object of the present invention is to provide an electrical connector which enables reliable connection between two electrical connectors or two electrical packages.  
       [0009] A further object of the present invention is to provide a carrier strip configured to efficiently contain adjacent electrical contacts having high elasticity.  
       [0010] In order to achieve the first abovementioned object, an electrical contact used in a connector in accordance with a preferred embodiment of the present invention comprises a medial portion, a cantilever extending from a top end of the medial portion, and a solder portion adapted to connect with a PCB extending from an opposite bottom end of the medial portion. The cantilever comprises a vertical body portion, and an arm portion extending obliquely from a distal end of the body portion away from the medial portion. An obtuse angle is defined between the medial portion and the arm portion. An arcuate contact portion is defined at a distal end of the arm portion, for electrically connecting with a conductive pad of the electrical package. When the contact is connected to the electrical package, the body portion and the arm portion cooperatively elastically deform thus providing the contact with excellent elasticity.  
       [0011] In order to achieve the second abovementioned object, a related ball grid array (BGA) connector in accordance with a preferred embodiment of the present invention comprises an insulative housing and a plurality of the above-described contacts received in the housing.  
       [0012] In order to achieve the third abovementioned object, a carrier strip in accordance with a preferred embodiment of the present invention comprises an operation carrier connected with a series of preforms of the above-described contacts. The arm portion of each perform extends beyond a distal end of the body portion of an adjacent perform. In addition, the arm portions of adjacent preforms are substantially parallel to each other. Thus the arm portions of the preforms can be configured to any suitable length to provide desired elasticity thereof.  
       [0013] Other objects, advantages and novel features of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0014]FIG. 1 is an isometric view of a contact for an electrical connector in accordance with a preferred embodiment of the present invention.  
     [0015]FIG. 2 is a top elevation view of an operation carrier in accordance with a preferred embodiment of the present invention.  
     [0016]FIG. 3 is a top elevation view of part of a housing of a BGA electrical connector in accordance with a preferred embodiment of the present invention, showing a plurality of contacts of FIG. 1 received in the housing.  
     [0017]FIG. 4 is a cross-sectional view of the housing of FIG. 3 taken along line IV-IV thereof, also showing a bottom solder portion of a contact in the housing connected with a PCB via a solder ball, and an electrical package above the housing ready to be connected with the contact.  
     [0018]FIG. 5 is similar to FIG. 4, but showing the electrical package connected with the contact.  
     [0019]FIG. 6 is a simplified, isometric view of a base of a conventional electrical connector.  
     [0020]FIG. 7 is an enlarged, top elevation view of part of the base of FIG. 6.  
     [0021]FIG. 8 is an isometric view of a conventional contact.  
     [0022]FIG. 9 is a top elevation view of a conventional operation carrier comprising a series of preforms of contacts of FIG. 8. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     [0023] Reference will now be made to the drawing figures to describe the present invention in detail.  
     [0024] Referring to FIGS. 3 and 4, a plurality of electrical contacts  1  in accordance with a preferred embodiment of the present invention are received in an electrical connector for electrically connecting an electrical package  3  with a printed circuit board (PCB)  5 . In a preferred embodiment of the present invention, the electrical connector is a ball grid array (BGA) connector. The connector comprises an insulative housing  2  defining a plurality of passageways  20 , the passageways  20  being parallel to one side of the housing  2 .  
     [0025] Referring also to FIG. 1, each contact  1  comprises a medial portion  10 , a cantilever  12  connecting with a top end of the medial portion  10 , and a solder portion  14  perpendicularly extending from an opposite bottom end of the medial portion  10 . The solder portion  14  electrically connects to a conductive pad  50  of the PCB  5  via a solder ball  4  soldered on the solder portion  14 . A plurality of barbs  100  extends from opposite sides of the medial portion  10 , for interferentially fastening the contact  1  in a corresponding passageway  20  of the housing  2 . The cantilever  12  comprises a body portion  121  extending upwardly from the medial portion  10 , and an arm portion  120  extending obliquely from a distal end of the body portion  121 . An obtuse angle α is defined between the medial portion  10  and the arm portion  120  (see FIG. 3). An arcuate contact portion  122  is defined at a distal end of the arm portion  120 , for electrically connecting with a conductive pad  30  of the electrical package  3 . A rib  124  is formed along a length of the body portion  121 , for reinforcing the cantilever  12 .  
     [0026] Referring also to FIG. 2, a carrier strip  6  comprises an operation carrier  60  connected with a series of preforms of the contacts  1  by a series of interposing connecting portions  601 . The arm portion  120  of the cantilever  12  of each preform extends obliquely from one side edge of a distal end of the body portion  121 . An oblique angle β is defined between the operation carrier  60  and the arm portion  120 . The arm portion  120  extends beyond a distal end of the body portion  121  of an adjacent perform. In addition, the arm portions  120  of adjacent preforms are substantially parallel to each other. Thus a length of each arm portion  120  is not restricted by a proximity of the body portion  121  of the adjacent preform, and is not restricted by configurations of arm portions  120  of adjacent preforms. Accordingly, the arm portions  120  can be configured to any suitable length to provide desired elasticity thereof.  
     [0027] Referring to FIGS. 4 and 5, each contact  1  is received in the housing  2  of the connector. Before the contact  1  is connected to the electrical package  3 , the body portion  121  extends coplanarly from the medial portion  10 , and the arm portion substantially protrudes out from the receiving hole  20  of the housing  2 . When the electrical package  3  is driven down by externally applied force, the conductive pad  30  presses the contact portion  122  and causes the arm portion  120  to elastically deform, which further causes a top part of the body portion  121  to elastically deform toward a middle of the passageway  20 . This cooperative elastic deformation of the arm portion  120  with the body portion  121  provides the cantilever  12  with excellent elasticity.  
     [0028] While the present invention has been described with reference to specific embodiments, the description is illustrative of the invention and is not to be construed as limiting the invention. Various modifications to the present invention can be made to the preferred embodiments by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.