Patent Document

BACKGROUND OF THE INVENTION 
     1. Field of The Invention 
     The present invention relates to a zero insertion force socket for a CPU package which is fixed on a frame with the pins thereof inserted into the socket with substantially zero insertion force and being capable of in electrical connection with contacts received in the socket when the socket is changed from a loosened state to a tightened state. 
     2. Related Art 
     Conventional zero insertion force (ZIF) sockets are usually installed with an actuation mechanism for controlling insertion/withdrawal of a CPU package. This actuation mechanism is normally controlled by a handle which is operated in a horizontal manner thereby positioning the socket between a loosened state and a tightened state as disclosed in the U.S. patent application Ser. No. 09/131,140 which is assigned to the same assignee of the present application. In the loosened state the socket is prepared for insertion of the CPU package or withdrawal thereof with substantially zero insertion force. In the tightened state, the socket firmly secures pins of the CPU package therein preventing withdrawal of the CPU package. This ZIF socket works well if the CPU package is directly positioned thereon. However, if the CPU package is fixed in a frame with the pins thereof extending downward into the socket, the movement of the cover with respect to the base will force the pins of the CPU package to move thus damaging the pins of the CPU package due to the retention of the CPU package in the frame. 
     It is requisite to provide a new ZIF socket which can eliminate the damaging problem as described. 
     SUMMARY OF THE INVENTION 
     The primary purpose of the present invention is to provide a zero insertion force socket which is operative to move contacts therein to be in contact with pins of a CPU package fixed on an external frame without moving the pins of the CPU package. 
     Another purpose of the present invention is to provide an electrical assembly having a CPU package fixed on a frame, with pins of the CPU package inserted into a socket with substantially zero insertion force and being in contact with contacts movably received in the socket. 
     In accordance with one aspect of the present invention, a socket comprises a base having a plurality of lower passageways each of which receives a contact which has an upper section extending upward beyond the base. A cover has a plurality of upper passageways each of which is in communication with one of the lower passageways and adjacent to a retention aperture which accommodates the upper section of the contact. The cover is movably engaged with the base so that when the cover is moved with respect to the base, each contact will be bent by the cover. 
     In accordance with another aspect of the present invention, an electrical assembly comprises an electrical package fixed in a frame with a plurality of pins extending from the electrical package while not blocked by the frame. A socket comprises a cover movably engaged with a base, wherein the cover defines a plurality of upper passageways communicating with corresponding lower passageways defined in the base, and a plurality of contacts each are partially received in the lower passageway and partially engaged with the cover. Each pin of the electrical package is inserted into a communicated pair of the upper passageway and the lower passageway and remains stationary when the upper passageway is moved with respect to the communicated lower passageway. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a zero insertion force socket in accordance with the present invention; 
     FIG. 2 is an enlarged partial view of FIG. 1 including a portion of a CPU package; 
     FIG. 3A is a perspective view of a contact used in the present invention; 
     FIG. 3B is a side view of the contact of FIG. 3; 
     FIG. 4A is a schematic view showing the socket of the present invention is in a neutral state; 
     FIG. 4B is a schematic view taken from another direction showing the socket is in the neutral state of FIG. 4A; 
     FIG. 5A is a schematic view showing the socket of the present invention is in a loosened state; 
     FIG. 5B is a schematic view taken from another direction showing the socket is in the loosened state of FIG. 5A; 
     FIG. 6A is a schematic view showing the socket of the present invention is in a tightened state; and 
     FIG. 6B is a schematic view taken from another direction showing the socket is in the tightened state of FIG.  6 A. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a ZIF socket in accordance with the present invention comprises a rectangular base  1 , a rectangular cover movably connected to the base  1 , and a cam lever  3  pivotally received between the cover  2  and the base  1  for selectively driving the cover  2  to move along opposite directions of a virtual line  6  parallel to opposite sides of the cover  2 . The cover  2  has a hole  20  which is bound by a forward follower side portion  21 , a backward follower side portion  26  and two parallel walls (not labeled) between the side portions  21 ,  26 . The cam lever  3  has a cam  3 A formed at one end thereof comprising a pivot  31  extending downward for pivotally engaging with the base  1 . The cam  3 A is confined in the hole  20  of the cover  2  and comprises a forward driving portion  32  operative to move the cover  2  forward on the forward follower side portion  21  thereof, and a backward driving portion  33  operative to move the cover  2  backward on the backward follower side portion  26  thereof. 
     The cover  2  defines a plurality of upper passageways  200  each of which is adjacent to a corresponding retention aperture  210  defined through the cover  2 . Referring to FIG. 2, each upper passageway  200  has a main portion  200 A and a branch portion  200 B communicating with the main portion  200 A, wherein the main portion  200 A is conical for facilitating insertion of CPU pins  81  extending from a CPU  8 . The main portion  200 A is circular and has a diameter greater than the width of the branch portion  200 B for indicating and guiding a user to insert the CPU pin  81  thereinto. 
     Referring to FIG. 4B, the base  1  defines a plurality of lower passageways  10  (only one is shown) each of which has a lower narrow portion  100  extending downward through the base  1 . Each lower passageway  10  communicates with a corresponding upper passageway  200  and receives a contact  5  therein, wherein the contact  5  exposes to exterior via the lower narrow portion  100 . 
     Referring to FIGS. 3A and 3B, the contact  5  comprises an upper straight section  51  connected to a middle diverged section  52 , a contacting section  53  extending from an intersection between the upper section  51  and the diverged section  52 . An engagement section  54  extends from two sides of the diverged section  54 . A solder tail  55  extends downward from the engagement section  54 . 
     Referring to FIGS. 4A, each lower passageway  10  (shown by phantom line) has opposite side narrow portions  10 A for firmly retaining the engagement section  54  of the contact  5 . Further referring to FIG. 42, each lower narrow portion  100  of the lower passageway  10  has a diverged portion  10 B defined at a lower end thereof. When assembling, the contact  5  is top loaded into the lower passageway  10  and the cover  2  is then assembled to the base  1 , with each retention aperture  210  thereof accommodating the upper section  51  of the contact  5 . The retention aperture  210  is diverged at a lower portion which is bound by opposite tapered walls  210 A. A solder ball  9  is then soldered to the soldering tail  55  of the contact  5  and partially received in the diverged portion  10 B partially extending outward beyond the diverged portion  10 B. The solder ball  9  is then soldered onto conductive traces of a printed circuit board (not shown) to which the socket is mounted. The lower narrow portion  100  of the lower passageway  10  can effectively prevent wicking problem during soldering procedure due to its narrow width. The socket is in a neutral state as shown in FIGS. 4A and 4B, wherein the contact  5  remains straight and the socket is not ready for receiving CPU pins  81  inserted therein. 
     Also referring to FIGS. 5A and 5B, the cover  2  is driven by the cam lever  3  to a loosened state in which a vertical space constituted by the main portion  200 A of the upper passageway  200  and the lower passageway  10  can receive the CPU pin  81  extending from the CPU  8  with substantially zero insertion force. The CPU  8  is in advance fixed in a frame  7  before the pins  81  thereof being inserted into the socket. The upper section  51  of the contact  5  is bent by the cover  2  especially by one of the tapered walls  210 A bounding the engagement aperture  210 . The engagement section  54  can absorb most of the tension due to the bending of the upper section  51  thereby preventing the solder ball  9  from being damaged when the socket is changed from the neutral state to the loosened state. Under this situation, the contacting section  53  is in an disengagement position which is away from the engagement position where the contacting section  53  substantially mechanically and electrically connects to the corresponding pin  81 . 
     After the CPU pins  81  is inserted into the socket, the socket may be operated from the loosened state to a tightened state as shown in FIGS. 6A and 6B. When the socket is changed from the loosened state to the tightened state, the cover  2  is driven by the cam lever  3  thereby bending the contact  5  from the upper section  51  thereof and rendering the contacting section  53  thereof to be in contact with the CPU pin  81 . The CPU pin  81  remains stationary when the cover  2  moves from the loosened state to the tightened state. The branch portion  200 B of the upper passageway  200  provide a free space allowing the cover  2  to move with respect to the CPU pin  81  without forcing the CPU pin  81  to move accordingly. Specifically, the contact  5  is driven by one of the tapered walls  210 A bounding the engagement aperture  210 . The base  1  and the CPU  8  remain stationary when the cover  2  is moved from the loosened state to the tightened state. 
     While the present invention has been described with reference to a specific embodiment, the description is illustrative of the invention and is not to be construed as limiting the invention. Therefore, various modifications to the present invention can be made to the preferred embodiment by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claims.

Technology Category: 5