Electrical connectors – With coupling movement-actuating means or retaining means in... – Retaining means
Reexamination Certificate
1999-06-28
2001-10-02
Sircus, Brian (Department: 2839)
Electrical connectors
With coupling movement-actuating means or retaining means in...
Retaining means
C439S327000, C439S411000, C361S740000
Reexamination Certificate
active
06296509
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention broadly relates to computer systems, and more particularly, to a computer system where one circuit board is vertically mounted on another circuit board using a torque-limiting screw.
2. Description of the Related Art
A computer system generally comprises a number of circuit boards, which carry a large number of electronic components mounted thereon. A motherboard in a computer system is one such typical circuit board. The motherboard carries one or more processors (or “microprocessors”) along with a number of memory modules inserted into corresponding sockets provided on the motherboard. A motherboard may further include a number of high density sockets, i.e., sockets having a large number of conducting paths. An external circuit board may be inserted into a high density socket on the motherboard to extend, e.g., memory capacity, of the computer system. The external circuit board may be inserted into the corresponding socket on the motherboard manually with or without further tightening by a screw.
Current screw designs, however, allow a user to “overtighten” a screw such that the user may continue rotating the screw head and advancing the screw even when the two objects to be fastened with the screw are already properly fastened. This overtightening may sometimes result in breakage or damage of one or both of the objects being fastened by the screw. This may not be desirable in certain applications, e.g., where two circuit boards in a computer system are to be fastened, or where the breakage or damage may be expensive or time-consuming to repair. Further, the overtightening may result in blunting of the grooves within the screw receiving surface, which may result in a permanently loose joint unless some additional measures are taken to maintain the screw rigidly fastened. Additionally, a loose screw may fall off the joint during transportation or due to vibrations.
In some applications, a circuit board that is vertically mounted on the motherboard may have a high density connecting edge that requires a high engagement force and a small engagement distance during insertion into a corresponding high density connector socket on the motherboard. It may therefore be desirable to limit the applied torque to prevent overtightening while inserting one circuit board into a socket on another circuit board, e.g., the motherboard, using screw type threaded fasteners.
SUMMARY OF THE INVENTION
The problems outlined above may in large part be solved by utilization of a pair of torque-limiting screws to secure one circuit board into a socket on another circuit board, e.g., a motherboard, in a computer system. The pair of torque-limiting screws may be mounted on a first pair of parallel edges of the circuit board. In one embodiment, the torque-limiting screws are mounted on the circuit board using a pair of brackets.
A support structure comprising a pair of grooved channels may be mounted on the motherboard with the pair of grooved channels remaining perpendicular to the motherboard surface and parallel to the direction of insertion of the circuit board. The support structure may be a flat surface or may be a shroud containing one or more CPU (Central Processing Unit) modules with the top surface of the shroud having the grooved channels on its respective edges. The support structure is mounted on the motherboard in such a way as to have the top of the support structure aligned with the socket (on the motherboard) that receives the circuit board.
Each threaded portion of a corresponding torque-limiting screw on the circuit board is brought in front of a corresponding one of the grooved channels on the support structure. The high density connecting edge of the circuit board is maintained in alignment with the longitudinal opening in the socket on the motherboard. The torque-limiting screws may then be fastened into the corresponding grooves by rotating the heads of the respective torque-limiting screws. The high insertion force provided by the torque-limiting screws facilitates secure engagement of the connecting edge of the circuit board into the longitudinal opening of the high density connector slot on the motherboard.
The transmission of excessive torque to the circuit board, and, hence, extended forward movement of the circuit board connecting edge into the socket on the motherboard is however restricted because of the torque-limiting screws. Because of the prevention of “overtightening”, the vertical circuit board may be inserted into the high-density socket on the motherboard without any breakage or damage to the delicate conducting edge of the circuit board.
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Kitlas Kenneth
Leung Winnie C.
Patel Anita
Conley Rose & Tayon PC
Kivlin B. Noäl
Nguyen Son V.
Sircus Brian
Sun Microsystems Inc.
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