Retention mechanism

[0002] The present invention relates to a retention mechanism, and particularly to a retention mechanism having a simple fixing structure for securely fixing the retention mechanism to a circuit board.

[0003] Conventionally, a CPU package connects with a circuit board through a connector, wherein the CPU package and the connector are horizontally oriented on the circuit board. Such a configuration has a disadvantage that a large amount of the circuit board space is occupied by the connector and the CPU package. Recently, a new type of connector which vertically connects a CPU package to a circuit board was developed. This type of connector requires a vertical retention mechanism for securing the CPU package to the connector. Furthermore, a fixing device is needed for mounting the retention mechanism on the circuit board.

[0004] Referring to FIG. 1, a conventional retention mechanism comprises a pair of leading arms 52 attached at lateral sides of a base frame 51. The base frame 51 forms a pair of bases 53 at lateral sides thereof, each base 53 forming a pair of receiving holes 531 for receiving corresponding engaging members 61 therein. A plurality of screws 62 attaches a pair of locking pads 63 to a circuit board 7. The screws 62 extend through holes 631 in the pads 63, and then locking holes 71 formed in the circuit board 7 to engage with corresponding engaging members 61 for fixing the base frame 51 to the circuit board 7.

[0005] However, the assembly process is complicated, and is not well suited for mass production. Furthermore, the screws 62 are made of metal which requires expensive machining.

[0006] Thus, there is a need for an improved fixing device with fewer, more reliable locking elements for simplifying the manufacturing process.

[0007] A main object of the present invention is to provide a retention mechanism having a fixing device with improved locking elements for facilitating the assembly process.

[0008] To fulfill the above-mentioned object, a fixing device according to a preferred embodiment of the present invention comprises a pair of locking screws and an engaging member. Each locking screw comprises a circular head and a post. The engaging member comprises a base pad and a pair of locking silos formed on lateral sides of the base pad.

[0009] The locking silo extends through a hole of a circuit board and a receiving hole of a retention mechanism, and the locking screw is inserted into a hole of the locking silo. Thus, the locking silo is expanded by the post and an engaging force is provided between the locking silo and the circuit board. Therefore the retention mechanism is securely fixed to the circuit board. For facilitating insertion of the locking screw, the end of the locking screw is formed with a subulate shape and the cap forms a central slot.

[0010] Other objects, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0011] FIG. 1 is an exploded view of a conventional retention mechanism and a circuit board;

[0012] FIG. 2 is an exploded view of a retention mechanism in accordance with the present invention and a circuit board;

[0013] FIG. 3 is a partial, cross-sectional view of a fixing device locking the retention mechanism to the circuit board;

[0014] FIG. 4 is a perspective view of an alternative fixing device; and

[0015] FIG. 5 is a cross-sectional view of the alternative fixing device assembled with the circuit board.

[0016] Referring to FIGS. 2 and 3, a retention mechanism 5 comprises a frame 3 and a pair of retaining arms 32 vertically formed at lateral sides of the frame 3. The frame 3 has a body 31 defining a central channel 311 for receiving a connector (not shown) therein. A CPU package (not shown) will be inserted into the mechanism 5 to electrically connect with a circuit board 4 through the connector, which is well known by those skilled in the art. A pair of bases 33 is formed at lateral sides of the frame 3, each base forming a pair of receiving holes 331. A pair of fixing devices each comprises a pair of locking screws 2 and an engaging member 1. Each locking screw 2 comprises a circular head 21 defining a slot (not labeled) for facilitating a manipulation of the screw 2 by a flat screwdriver (not shown) and a conical threaded post 22 extending downwardly from the head 21. The engaging member 1 comprises a base pad 10 and a pair of locking silos 11 upwardly projecting from lateral sides of the base pad 10. Each silo 11 defines a central hole 12 therein.

[0017] During assembly, the locking silos 11 are extended through corresponding holes 41 in the circuit board 4 and then the receiving holes 331. Thereafter, the locking screws 2 are driven into the corresponding holes 12 of the locking silos 11. Thus, each locking silo 11 is expanded by the post 22 to tightly engage with the bases 33 and the circuit board 4. Therefore the retention mechanism 5 is securely fixed to the circuit board 4.

[0018] FIGS. 4 and 5 illustrate another embodiment of the fixing device. The fixing device comprises an engaging member 1′ and a pair of locking posts 2′. Each locking post 2′ comprises a cap 21′ at a top free end. A truncated cone 23′ forms the transition between the cap 21′ and a cylindrical shank 25′, and a tip portion 24′ is formed at the bottom free end of the locking post 2′. A central slot 241′ is formed in the tip portion 24′ for enhancing the resilience of the tip portion 24′. The slot 241′ divides the tip portion 24′ into two symmetrical halves 242′ each having a slanting, up-facing face 243′. The engaging member 1′ comprises a base pad 10′ and a pair of locking silos 11′ projecting upwardly from lateral sides of the base pad 10′. Each of the locking silos 11′ forms a head 112′ at a top portion thereof. A hole 12′ is defined in each silo 11′. A slot 113′ is defined through the head 112′ to divide the head 112′ into two symmetrical halves 114′ to increase the resilience of the head 112′. Each half 114′ has a slanting, down-facing face 115′.

[0019] During assembly the locking silos 11′ are extended through corresponding holes 41′ in a circuit board 4′ and then receiving holes 331′ of a base 33′ of a retention mechanism. The engaging member 1′ is fixed in position by an engagement between the base 33′ and the slanting, down-facing faces 115′ of the head 112′. The locking posts 2′ are thereafter inserted into the holes 12′ to reach a position as shown in FIG. 5, wherein the tip portions 24′ extend through the holes 12′ and the slanting, up-facing faces 243′ tightly engage with a bottom face (not labeled) of the base pad 10′. Each head 112′ is expanded outwardly by the corresponding truncated cone 23′ to further tightly engage with the base 33′. Thus, the retention mechanism is securely mounted on the circuit board 4′.

[0020] Thus, the fixing device is simplified compared to the conventional design having only two elements, and the assembly process is more effective.

[0021] 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.