Patent Application
20070253769
The present invention relates generally to a fastening device, and more particularly to a fastening device for mounting a thermal module onto a heat generating electronic component.
A thermal module includes a die-casting member, a heat pipe, a fin assembly and a strip-like spring member. The die-casting member has a bottom surface contacting with a heat-generating electronic component mounted on a circuit board. The heat pipe includes an evaporator section received in a receiving channel of the die-casting member, and a condenser section contacted with the fin assembly. The spring member includes a middle portion contacting with an upper surface of the die-casting member, and two ends for being attached to the circuit board. When the ends of the spring member are attached to the circuit board, the middle portion of the spring member urges the die-casting member toward the circuit board to mount the thermal module thereon, whereby the die-casting member can have an intimate contact with an electronic component mounted on the circuit board.
In the thermal module, the die-casting member is formed by injecting molten metallic materials into a mold. Such way of producing the die-casting member complexes the manufacture of the thermal module and increases the weight of the thermal module. These factors in turn increase the cost of the thermal module and violate the need of lighter electric products. So a thermal module with lower cost and lighter weight is needed.
The present invention relates to a fastening device for mounting a thermal module onto a heat generating electronic component. According to a preferred embodiment of the present invention, the fastening device includes a base member and a resilient spring member. The base member includes a contacting plate for contacting with the electronic component, and a receiving channel for receiving an evaporating portion of a heat pipe of the thermal module therein. The resilient spring member includes two ends for being attached to a board with the electronic component mounted thereon, and a middle portion contacted with the evaporating portion of the heat pipe to sandwich the evaporating portion of the heat pipe between the base member and the spring member.
Other advantages and novel features of the present invention will become more apparent from the following detailed description of preferred embodiment when taken in conjunction with the accompanying drawings, in which:
Referring to
The base member 14 is formed by stamping a blank plate 14a, shown in
The spring member 15 is made of resilient materials, such as steel, copper, or aluminum. The spring member 15 includes a bulge 151 stamped downwardly from a middle portion thereof, two locating holes 152 symmetrically defined at two sides of the bulge 151, and two pierces 153 defined adjacent to two ends of the spring member 15. As the spring member 15 is mounted to the base member 14, the bulge 151 abuts against an upper surface of the evaporator section 121 of the heat pipe 12, and urges the evaporator section 121 of the heat pipe 12 to move downwardly to intimately contact with the contacting plate 141 of the base member 14. Alternatively, the bulge 151 of the spring member 15 may be canceled, if the thickness D of the evaporator section 121 of the heat pipe 12 is a bit greater than the depth H of the receiving channel 147. Under this condition, a bottom surface of the middle portion of the spring member 15 abuts against the upper surface of the evaporator section 121 of the heat pipe 12, and urges the evaporator section 121 of the heat pipe 12 to intimately contact with the contacting plate 141 of the base member 14.
In assembly of the thermal module 10, the thermal grease is spread in the receiving channel 147 of the base member 14. The evaporator section 121 of the heat pipe 12 is disposed in the receiving channel 147 of the base member 14. The spring member 15 is mounted onto the wings 143 of the base member 14, with the locating pins 144 of the base member 14 extending through the locating holes 152 of the spring member 15. The locating pins 144 are flattened downwardly to abut against an upper surface of the spring member 15. Meanwhile, the bulge 151 of the spring member 15 aligns with the central point O of the base member 14 and intimately abuts against the upper surface of the evaporator section 121 of the heat pipe 12. The bulge 151 of the spring member 15 urges the evaporator section 121 of the heat pipe 12 to move downwardly to intimately contact with the contacting plate 141 of the base member 14. Thus, the evaporator section 121 of the heat pipe 12 is intimately sandwiched between the spring member 15 and the base member 14, and the heat pipe 12 is preassembled to the fastening device 11. Finally, a plurality of fixing members (not shown) such as screws extends through the pierces 153 of the spring member 15 and the circuit board to securely connect with a back plate at a bottom of the circuit board, thereby urging the spring member 15 to distort downwardly toward the circuit board, and thereby fixing the thermal module 10 onto the circuit board with the contacting plate 141 of the base member 14 intimately contacting with the heat-generating component.
In the present invention, the base member 14 of the fastening device 11 is formed by stamping the blank plate 14a. The blank plate 14a is lighter than the die-casting member of the related art. Thus, the weight of the thermal module 10 is decreased. Furthermore, such way of manufacturing the base member 14 simplifies the produce of the thermal module 10, thereby reducing the cost of the thermal module 10. In addition, the locating pins 144 are centrosymmetric to each other in respect to the central point O of the base member 14. This makes the force of the spring member 15 exerted on the evaporator section 121 of the heat pipe 12 be evenly distributed around the central point O of the base member 14. The force is transferred to a central area of a contacting surface between the contacting plate 141 of the base member 14 and the heat-generating electronic component. This prevents a middle portion of the contacting plate 141 of the base member 14 from distorting upwardly in case the force is exerted on sides of the contacting plate 141, which hinders heat conductivity between the base member 14 of the thermal module 10 and the heat-generating electronic component.
FIGS. 4 to 6 show a second embodiment of the present invention. The difference between this embodiment and the first embodiment is: the base member 14b extends a covering plate 148 upwardly from the contacting plate 141. When the spring member 15 is attached to the base member 14, the covering plate 148 is sandwiched between the evaporator section 121 of the heat pipe 12 and the middle portion of the spring member 15. The covering plate 148 contacts with the upper surface of the evaporator section 121 of the heat pipe 12, and disperses the force exerted by the bulge 151 of the spring member 15 over a larger area, thereby preventing the heat pipe 12 from being damaged by a concentrated force at the bulge 151. Moreover, the covering plate 148 increases contacting areas between the evaporator section 121 of the heat pipe 12 and the base member 14, thereby improving heat transfer therebetween. The heat dissipation efficiency of the thermal module 10 is further improved.
In the present invention, the locating pins 144 and the locating holes 152 are respectively formed on the base member 14 and the spring member 15. Alternatively, the locating pins 144 may extend from the spring member 15, while the locating holes 152 may accordingly be defined in the base member 14.
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.
