Patent Publication Number: US-2003228809-A1

Title: Terminals for an electrical socket

Description:
BACKGROUND OF THE INVENTION  
       [0001] 1. Field of the Invention  
       [0002] The present invention relates to a terminal for use in an electrical socket, and particularly to such a terminal which not only has a good desired performance but also can be easily assembled to the electrical socket.  
       [0003] 2. Description of Prior Art  
       [0004] With the miniature trend in computer technology, electrical sockets each of which mainly comprises an insulating housing and a plurality of terminals are becoming smaller and smaller. Due to their small size, the terminals, especially mating beams of the terminals are easily to be damaged because of overlarge stress produced therein when the terminals engage with pins of a complementary electronic package, such as a central processing unit (CPU). Several methods are proposed to solve this problem. One of them, for example as that disclosed in U.S. Pat. Nos. 5,860,838, and 6,227,869, is to modify the structure of the terminals so as to obtain optimal electrical and mechanical performance of the mating beams of the terminals. Another method is to modify the arrangement of the terminals with respect to a base of an insulating housing of the sockets, as disclosed in U.S. Pat. Nos. 4,750,891, and 5,518,426. As disclosed in U.S. Pat. No. 4,750,891, a base plate of an electrical socket defines an array of terminal holes arranged in a lattice-like shape for receiving corresponding terminals therein and the respective rows of the terminal holes are inclined at same angles, preferably 45 degrees, with respect to the respective sides of the base. In this way, not only miniaturization of the pith of adjacent terminals is advanced, but also intended performance of the terminal is obtained. However, the terminals can not be fitted into the lattice-shaped terminal holes of the base plate simultaneously, due to the limitation of existing manufacturing technology for the terminals, thereby complicating the assembly of the terminals. Furthermore, in forming the terminal holes oriented in 45 degrees, core pins of the molding mold should also be oriented in 45 degrees. This introduces a lot of complication in forming the molding mold. On the other hand, U.S. Pat. No. 4,917,614 defines some approach to use a 45 degrees contact in a connector for surface mount to a printed circuit board.  
       [0005] Hence, an improved terminal for use in an electrical socket is required to overcome the disadvantages of the prior art.  
       BRIEF SUMMARY OF THE INVENTION  
       [0006] A main object of the present invention is to provide a conductive terminal for use in an electrical socket, wherein the terminal has good intended performance and can be easily assembled in the socket.  
       [0007] To fulfill the above-mentioned object, a conductive terminal for use in an electrical socket in accordance with the present invention comprises a retaining body retained to a base of an insulating housing of the electrical socket, a soldering portion and a resilient arm both extending from the retaining body. The retaining body is parallel to one lateral side of the base during insertion into the base. The soldering portion extends horizontally from a bottom end of the retaining body for soldering to a printed circuit board. The resilient arm has a body portion connected to one side of the retaining body and a curved beam for conductively contacting with a conductive point of an electronic package. An angle is defined between the retaining body and the body portion of the resilient arm. The angle is an obtuse angle so that the curved beam extends substantially in a diagonal direction of a corresponding terminal hole receiving the terminal, whereby the curved beam can obtain an extended length.  
       [0008] Other objects, advantages and novel features of the invention will become more apparent from the following detailed description of the present embodiment when taken in conjunction with the accompanying drawings. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0009]FIG. 1 is a perspective view of a terminal for use in an electrical socket in accordance with the present invention;  
     [0010]FIG. 2 is a side view of FIG. 1;  
     [0011]FIG. 3 is a front view of FIG. 1;  
     [0012]FIG. 4 is a top view of FIG. 1;  
     [0013]FIG. 5 is an elevational view viewed from a direction indicated by a double-arrow line  5 - 5  of FIG. 4; and  
     [0014]FIG. 6 is a partial top view of the electrical socket of the present invention, having a number (four) of the terminals of FIG. 1 assembled to a base thereof. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0015] Referring to FIG. 1, there is shown a perspective view of a conductive terminal  1  incorporating inventive features of the present invention. The terminal  1  is used for an electrical socket, such as an LGA (Land Grid Array) socket, and electrically connects between an upper and a lower printed circuit boards (PCBs) (not shown).  
     [0016] Further referring to FIGS.  2  to  5 , the terminal  1  has a retaining body  10 , a soldering portion  12  horizontally extending from a lower end  11  of the retaining body  10  for soldering to the lower printed circuit board, and a resilient arm  16  extending from a lateral side  13  of the retaining body  10 , in which an obtuse angle α is formed between a body portion  17  of the resilient arm  16  and the retaining body  10 . The angle a preferably is 145 degrees. The retaining body  10  forms a plurality of barbs  14  at opposite sides  13  thereof, adjacent to the lower end  11  thereof, for retaining the terminal  1  to a terminal hole  24  (FIG. 6) of a base  22  of an insulting housing of the electrical socket  2 .  
     [0017] The resilient arm  16  has the body portion  17  and a curved beam  18  extending from an upper end of the body portion  17 . The resilient arm  16  tapers off from a lower end thereof to an upper end thereof, as best seen in FIG. 4. The curved beam  18  forms an arc free end  19  to conductively contact a corresponding conductive point (not shown) formed on the upper PCB when the upper PCB presses the arc free end  19  downward. Thus, the curved beam  18  needs a length which is sufficiently long to bear the stress generated by the downward pressing force from the upper PCB. To fulfill this demand, as best seen in FIG. 6, the angle a, which is defined between the body portion  17  and the retaining body  10 , is an obtuse angle (145 degrees) in accordance with the preferred embodiment of the present invention. By this arrangement, the curved beam  18  extends substantively in a diagonal direction W of a corresponding terminal hole  24  of the base  22  of the socket  2  so as to obtain its possibly maximal length in the hole  24 , whereby the curved beam  18  can more effectively resist the stress generated by the depressing force of the upper PCB.  
     [0018] In assembly, referring to FIG. 6, the terminals  1  extend from a common contact carrier (not shown) are inserted simultaneously from above of the base  22  into corresponding terminal holes  24  of the base  22 . It is noted that during this insertion course, the retaining bodies  10  of the terminals  1  are parallel to two corresponding opposite side edges (not shown) of the base  2  and a longitudinal direction of the holes  24 . Thus, the assembly of the terminals  1  to the base  2  in accordance with the present invention is just a single operation, which is more simple with respect to the assembly of the terminals in the prior art. Meanwhile, each of the resilient arms  18  extends in the diagonal direction W of a corresponding hole  24 . Thus, the curved beams  18  of the terminals  1  in accordance with the present invention can provide sufficient resiliency to meet the operational requirement in mating the upper PCB with the electrical socket  2 .  
     [0019] It is to be understood, however, that even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.