Abstract:
A burn-in includes a base, a number of contacts received in the base, and a cover pivotally mounted to the base and rotatably moving between an open position and a closed position. The base defines a receiving space and a plurality of recesses adjacent to and communicating with the receiving space. Two hard stoppers are mounted to the recesses of the base and support upwardly the cover.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a burn-in socket, and more particularly to a socket having a hard stopper disposed within a base for precisely controlling a stroke of a contact mounted in the base. 
         [0003]    2. Description of the Prior Art 
         [0004]    Electronic packages are installed in a printed circuit board to construct a complete circuit with continuous functions. To ensure the functionality and reliability of the electronic package during service life, the electronic package must be tested before actual field application. The electronic package in the test usually undergoes an extended period of time at a high temperature, so that any earlier failure of a package can be detected accordingly. A so-called burn-in socket servers for connecting the electronic package to a test printed circuit board. 
         [0005]    Tai Wan Pat No. M324868, issued to Hsiao on Jan. 1, 2008, discloses a typical burn-in socket. The burn-in socket includes a socket body with a plurality of contacts disposed therein, a cover rotatably coupled to the socket body and at least one slider received in the socket body. The socket body defines a receiving space for receiving an IC (integrated circuit) package, and the cover has a driving member. The slider has an end engaging with the driving member and another end extending toward the receiving space. When the burn-in socket is in a closed position, the slider supports the IC package to keep a reliable connection between the burn-in socket and the IC package. The cover comprises a lid that is formed with a frame configuration, a pressing member assembled to a bottom of the lid and a metal fastener on a top of the cover. When the burn-in socket is in a closed position, the cover presses downwardly an upper surface of the IC package to make an electrical connection between the contacts and the IC package. On that condition, the stroke of the contact is related to the configuration of the cover. As the cover is an assembly, a composite tolerance is created between adjacent members of the cover. As we all known, the number of the assembled members is increased, the composite tolerance of the assembly is increased. Thus the length of the contact may be designed in a wide range for the cover may have a large tolerance. As a result, it&#39;s difficult to control the stroke of the contact, so we need to provide a new burn-in socket to overcome this question. 
       SUMMARY OF THE INVENTION 
       [0006]    Accordingly, an object of the present invention is to provide a burn-in socket with a hard stopper disposed within a base for exactly controlling a stroke of contact mounted in the base. 
         [0007]    In order to achieve the object set forth, a burn-in comprises a base defining a receiving space, a plurality of contacts received in the receiving space, and a cover pivotally mounted to the base and rotatably moving between an open position and a closed position relative to the base. At least one separated hard stopper is mounted to the recess of the base and supporting the cover. 
         [0008]    In order to further achieve the object set forth, a burn-in socket comprises a base defining a receiving space, a plurality of contacts received in the receiving space of the base, and a cover pivotally mounted to the base and rotatably moving between an open position and a closed position. The cover has a pressing portion extending into the receiving space when the cover set in the closed position, the pressing portion has a plurality of protrusions extending therefrom. A separated hard stopper is mounted to the base adapted to load with the protrusion of the cover. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is an assembled perspective view of a burn-in socket according to the present invention; 
           [0010]      FIG. 2  is a partially exposed perspective view of a cover of the burn-in socket according to the present invention; 
           [0011]      FIG. 3  is a partially exposed perspective view of a base of the burn-in socket according to the present invention; 
           [0012]      FIG. 4  is a schematic view of the burn-in socket with an IC package thereof, showing the cover at a closed position. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
       [0013]    Reference will now be made to the drawings to describe the present invention in detail. 
         [0014]      FIG. 1  shows a burn-in socket electrically connecting an IC package  4  with a printed circuit board (not shown) and used for testing the IC package  4 . The burn-in socket comprises a base  2 , a plurality of contacts  7  disposed in the base  2 , a cover  3  pivotally mounted to the base  2  and rotating between an open position and a closed position relative to the base  2 , and a heat sink  5  fixed to the cover  3 . 
         [0015]    Referring to  FIG. 3 , the base  2  includes a rectangular frame  20  and a bottom plate  21  positioned at a bottom of the frame  20 . The frame  20  is substantially a rectangular shape and has a receiving space  201  at a center thereof for accommodating the IC package  4 . The frame  20  defines two first recesses  202  communicating with the receiving space  201  but not extending through the frame  20  on two opposite walls thereof. The frame  20  further defines two second recesses  203  similar with the first recesses  202  on the other two opposite walls. The first and the second recesses  202 ,  203  all have bottom walls. A hard stopper  204  is disposed on the bottom wall  2030  of the second recess  203  for engaging with and supporting the cover  3 . The hard stopper  204  is made of metal plate or other hard materials. The hard stopper  204  and the bottom wall  2030  of the second recess  203  each define a pair of corresponding screw holes  2040 ,  2031 , a pair of screws  205  pass through the screw holes  2040 ,  2031  to secure the hard stopper  204  to the bottom wall of the recess  203 . The bottom plates  21  are attached to the bottom of the frame  20  and have a plurality of passageways (not labeled) for receiving and securing the contacts  7 . The bottom plates  21  can also provide a supporting surface to support the IC package  4 . 
         [0016]    Referring to  FIG. 2 , the cover  3  comprises a lid  31  and a cover plate  32 . One end of the lid  31  is pivotally connected to the base  2  by a shaft  6 , the other end of the lid  31  is pivotally connected to the cover plate  32  by a rod  34 . The lid  31  is formed with a frame configuration for locating a pressing member  310 . The lid  31  and the pressing member  310  are connected by bolts (not shown) inserting from a side of the lid  31 . Each of the lid  31  and the pressing member  310  has a through hole  3100  for receiving the heat sink  5 . The cover plate  32  also has a hole (not labeled) corresponding to the through hole  3100 , and the heat sink  5  is assembled to the cover  3  along an up-to-down direction with a contacting surface  50  extending through the through hole  3100 . The pressing member  310  comprises a main body  311  and a pressing portion  312  protruding from a bottom of the main body  311 . Protrusions  3120  extend from the opposite ends of the pressing portion  312  and touch the hard stoppers  204  in the second recesses  203  when the cover  3  is in the closed position. The cover  3  is attached to the base  2  by a latch  33  mounted to one end of the cover plate  32 . 
         [0017]    Referring to  FIG. 4 , the hard stopper  204  in the second recess  203 , so that the hard stopper  204  can support the pressing member  310  when the cover  3  is in the closed position. On that situation, a stroke of the contact  7  caused by being pressed by the IC package  4  which is pressed by the pressing member  310  is therefore depended on the hard stopper  204  and the pressing member  310 , and the stroke is independent of the whole members of the cover  3 . As the members that are utilized to control the stroke of the contacts  7  are reduced, the composite tolerance generated by the members is reduced. Thus the stroke of the contacts  7  can be exactly controlled to avoid over pressing of the contacts  7 . 
         [0018]    As the burn-in socket may need to receive different thickness of the IC packages or assembled with another bottom plate with different contacts, the present burn-in socket just need to mount another hard stopper with a proper thickness to assure a proper mating of the hard stopper with the cover, and not need to change the cover. As a result, the present burn-in socket has a simple structure and a low cost. 
         [0019]    Although the present invention has been described with reference to particular embodiments, it is not to be construed as being limited thereto. Various alterations and modifications can be made to the embodiments without in any way departing from the scope or spirit of the present invention as defined in the appended claims.