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The invention relates to a radiation board adopted for use on heat generating elements of electronic devices, and particularly to a radiation board that is easy to fabricate at a low cost.
With continuous advances in semiconductor manufacturing techniques, the number of transistors in electronic elements and chip sets of electronic products is increasing. Electricity consumption and heat generated by the electronic elements have become urgent issues to be resolved.
Among the heat generating elements in electronic products, heat generated by the central processing unit (CPU) is most significant. Researching on heat dissipation techniques for the heat generating elements of electronic products is known in the art. FIG. 1 illustrates a conventional radiation device consisting of an upper lid 11 and a lower lid 12 that are coupled to form a housing compartment to house a conductive plate 13, a spacer 14 with cubical strips formed thereon and a flow channel plate 15. The housing compartment is divided into a plurality of flow passages to hold fluid. The fluid absorbs the heat generated by the heat-generating element and flows in the housing compartment. FIG. 2 depicts another radiation technique that has a case 20 housing a plurality of cubical members 21. Fluid is filled in the case 20 and channeled by the cubical members 21 to circulate inside the case 20. FIG. 3 shows yet another radiation technique that has a case 30 housing channel members 31 formed in special geometric shapes to channel a fluid to circulate in the case 30.
All the radiation devices mentioned above aim to distribute the heat energy of the heat-generating element evenly to the entire device to achieve heat dissipation. While they have some degree of effect, they consist of many elements and have complicated structures. Fabrication is difficult, production yield is undesirable and production cost is high. Thus there is still room for improvement.
The primary object of the invention is to provide a radiation board adopted for use on electronic products that is easier to fabricate at a lower cost.
The radiation board according to the invention mainly includes a case and a lid. The case has an inner wall forming a plurality of circulation channels and a bulged longitudinal strip between two neighboring circulation channels. The lid is bonded to the longitudinal strips and seals the case to keep an operation fluid in the case. The lid has miniature flutes corresponding to the circulation channels that are much smaller than the circulation channels. One side of the lid is in contact with a heat-generating element to transfer the heat that it generates during operation to the operation fluid filled in the case. A portion of the operation fluid is vaporized. Through the miniature flutes, the vaporized operation fluid is cooled and re-condensed into the liquid phase operation fluid, and circulated in the case through the circulation channels. Hence the heat generated by the heat-generating element during operation is evenly distributed on the entire device to achieve an improved heat dissipation effect.
The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.
FIG. 1 is a schematic view of a conventional radiation device.
FIG. 2 is a schematic view of another conventional radiation device.
FIG. 3 is a schematic view of yet another conventional radiation device.
FIG. 4 is an exploded view of the radiation board of the invention.
FIGS. 5A and 5B are fragmentary sectional and enlarged views of the radiation board of the invention.
Referring to FIGS. 4, 5A and 5B, the radiation board according to the invention is adopted for use on electronic products. It includes a case 40 and a lid 50. The case 40 has an inner wall forming a plurality of parallel circulation channels 41. The outer surface of the case 40 corresponding to circulation channels 41 has a plurality of radiation fins 60. Every two neighboring circulation channels 41 are interposed by a bulged longitudinal strip 43. There is a cross channel 42 running across the distal ends of the circulation channels 41 to allow the circulation channels 41 to communicate with one another.
The lid 50 is bonded tightly to the longitudinal strip 43 and seals the case 40 on one side. On the lid 50 there is a plurality of parallel miniature flutes 51 corresponding to the circulation channels 41. The miniature flutes 51 are smaller than the circulation channels 41, and are formed in a V-shape cross-section with an included angle of about 60 degrees. Moreover, the surface of the miniature flutes 51 is treated to make it coarse.
As the lid 50 is sealed on the case 40, the operation fluid 70 is confined in the case 40 and may flow freely among the circulation channels 41, cross channel 42 and miniature flutes 51. Many substances may serve as the operation fluid 70. Water and acetone are most commonly used.
The radiation board of the invention may be mounted onto the heat-generating element 80 of an electronic product to transfer and disperse the heat generated by the heat-generating element 80 during operation. When in use, first keep one side of the lid 50 in close contact with the heat-generating element 80; heat generated by the heat-generating element 80 is transferred through the lid 50 to the operation fluid 70 filled in the case 40; a portion of the operation fluid 70 absorbs the heat and becomes a vapor and liquid mixture, or is vaporized, depending on the kind of operation fluid 70 and the level of thermal energy provided by the heat-generating element 80. That is, the operation fluid 70 is vaporized if it absorbs enough heat. After the operation fluid 70 has absorbed the heat and filled in the closed space formed by the case 40 and the lid 50, it flows in the circulation channels 41, cross channel 42 and miniature flutes 51 under natural convection caused by differing temperatures and densities. The vaporized operation fluid 70 circulates in the case 40 due to channeling of the circulation channels 41. The coarse surface of the miniature flutes 51 helps to condense the vaporized operation fluid 70 into a liquid. Hence the heat generated by the heat-generating element 80 during operation is evenly distributed to the entire device and an improved heat dissipation effect is achieved.
Compared with the conventional heat radiation apparatus that are difficult to fabricate, have low production yields and high costs, the radiation board of the invention may be fabricated at a lower cost, and has an improved production yield.
While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.