Patent Publication Number: US-2006005944-A1

Title: Thermoelectric heat dissipation device and method for fabricating the same

Description:
BACKGROUND OF THE INVENTION  
      The present invention is related to a thermoelectric heat dissipation device and a method for fabricating the thermoelectric heat dissipation device. More particularly, the present invention is related to a thermoelectric heat dissipation device including a combination of a cryogenic chip and a heat sink in form of fins or flat plates and a method for fabricating the heat dissipation device.  
      The technology of electronic components is developed very fast, especially, the main component of a computer, central processing unit (CPU). The size of CPU is tended to miniaturize but the performance and the efficiency thereof is progressed. Due to the miniaturization of CPU, the heat generated from the power consumption when the CPU is operating is rapidly accumulated so as to increase the temperature of the CPU. Thus, if the heat is not adequately removed from the CPU, the CPU is overheated to levels that degrade the life and reliability of the computer, or worse to crash the CPU. Thus, heat dissipation of CPU is a significant issue during the operation of computers.  
      One of the heat dissipation devices on the market is utilization of a fan to couple to the enclosure of electronic apparatus. This heat dissipation device is designed to exhaust the hot air from the enclosure of the apparatus in order to replenish it with fresh air. Thus, the heat generated from the operation of the electronic components in the enclosure of an electronic apparatus will be dissipated. However, the efficiency of the heat dissipation of this kind of one-way fan is not satisfied because the environment temperature may not be lower than the interior temperature in the enclosure of an electronic apparatus, such as in summer time, the room temperature is high as 35 centigrade degrees. Thus, utilization of one-way fan for air-convection with high-temperature fresh air is inefficient, because the electronic components are still operated in an environment with high temperature. The efficiency cannot be improved by adding one-way fans to the apparatus.  
      Another one commercial heat dissipater for removing the heat generated from the electronic component is a device combined a base and a heat sink. The heat sink is coupled to the surface of the electronic components via the base for heat transfer. The heat is conducted via the heat sink and then transferred to the environment. A fan can be added to the heat sink to improve the efficiency of the heat transfer of the heat sink.  
      There is another one commercial electric heat dissipation device. As shown in  FIG. 1 , this kind of commercial heat dissipation device includes a cryogenic chip for heat exchange. A heat conducting surface is integrated with an afore-mentioned heat dissipation device. The heat generated from the electronic components is exchanged by the cryogenic chip to the surface of the heat conduct surface, and then is transferred to the integrated heat dissipation device. The heat thus is dissipated by the heat dissipation device or an additional fan. However, the cryogenic chip of the electronic heat dissipation device is consisted of an upper ceramic plate, a bottom ceramic plate and a P-N semiconductive material electric coupled therebetween. The heat conductivity of the ceramic material is lower than metal or a high heat conductivity material. Besides, because the heat is indirectly transferred from the plate to the heat dissipation device, the efficiency of heat conductivity of the electronic heat dissipation device is unsatisfied.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention is to provide a method for fabricating a thermoelectric heat dissipation device. The method includes the steps of providing a base plate, a thermoelectric semiconductive element connected to the base plate and a heat sink in form of plates or fins with one surface coated an electric insulation coating and patterned conductive lines, and adhering the heat sink to the thermoelectric semiconductive element. This thermoelectric heat dissipation device conducts the heat dissipation by direct heat transfer.  
      The present invention is further to provide a thermoelectric heat dissipation device. The present device includes a theremoelectric semiconductive element as a cryogenic chip and a heat sink. The cooling surface of the cryogenic chip is directly electrically connected to the heat sink which is in form of plates or fins, and the other surface of the cryogenic chip is adhered to a base plate. The base plate of the device is utilized to connect to the surface an electronic component for heat exchange.  
      Because the heat sink of the thermoelectric heat dissipation device is directly connected to the heat dissipating surface of the thermoelectric semiconductive element for transferring the heat exchanged from the electronic component to the semiconductive element, the efficiency of heat dissipation of the device is enhanced and the cost thereof is lowered compared with the prior thermoelectric device.  
      These and other objectives of the present invention will become obvious to those of ordinary skill in the art after reading the following detailed description of preferred embodiments.  
      It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      These as well as other features of the present invention will become more apparent upon reference to the drawings therein:  
       FIG. 1  is a perspective view of a conventional structure of a cryogenic chip and a heat sink;  
       FIG. 2  is a cross-sectional view of a base plate of the embodiment of the present invention;  
       FIG. 3  is a cross-sectional view of a base plate and a thermoelectric semiconductive element combined according to the embodiment of the present invention;  
       FIG. 4  is a cross-sectional view of a heat sink of the embodiment of the present invention; and  
       FIG. 5  is a cross-sectional view of the assembly of a heat sink and a thermoelectric semiconductive element of the embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.  
      FIGS.  2  to  5  are shown a preferred embodiment of the present invention to fabricate a thermoelectric heat dissipation device. The process of the present invention includes the step of providing a base plate  1 . The upper surface of the base plate  1  is patterned a plurality of conductive lines  41  for connecting with a thermoelectric semiconductive element  2  and providing the electrical connection of multiple P-N posts of semiconductive material  21  and  22 , as shown in  FIG. 1 . The upper surface is utilized to connect the thermoelectric semiconductive element  2 .  
      The thermoelectric element  2  is connected to one surface of the base plate  1  by a cooling surface  23  thereof, as shown in  FIG. 3 . Such that, the patterned conductive lines  41  is further electrically connected to a plurality of sets of P-N posts  21 ,  22  of the semiconductive element  2 .  
      Furthermore, a heat conductive element  3  is provided. The heat conductive element  3  is made of material with high heat conductivity but without electric conductivity. In a preferred embodiment, the heat conductive element  3  can be made of a metal with high heat conductivity. The surface  31  of the heat conductive element  3  for combining with the thermoelectric semiconductive element  2  is coated an inert coating  33 , such as an anodic coating. Thus, the coating  31  is heat conductive but is not electric conductive, as shown in  FIG. 4 . In a prefer embodiment of the present invention, the conductive element  3  includes the surface  31  patterned a plurality of conductive lines  42 , as shown in  FIG. 4 . The conductive lines  42  are utilized to connect to the thermoelectric semiconductive element  2  and to provide the electrical connection between P-N posts  21  and  22  of the semiconductive material.  
      The surface  31  of the heat conductive element  3  with the patterned conductive lines  42  is combined to the top surface  24  of the thermoelectric element  2 . The P-N posts of the semiconductive material are electrically connected to the surface  31  via the patterned lines  42 , as shown in  FIG. 5 .  
      According to the above description, a thermoelectric heat dissipation device is fabricated, as shown in  FIG. 5 . The heat dissipation device includes the thermoelectric semiconductive element  2  as a cryogenic chip and a heat sink  3 . The thermoelectric heat dissipation device is connected with an electronic component via base plate  1  thereof. Thus, the heat generated from the electronic components can be exchanged from the base plate  1  to the top of the thermoelectric semiconductive element  2  and then transferred to the heat sink  3  for heat dissipation. Accordingly, the heat can be directly transferred and dissipated to enhance the efficiency of the cryogenic chip. Moreover, in a preferred embodiment, the heat sink  3  can be directly adhered to the top surface  24  of the thermoelectric semiconductive element  2 . Comparing with the utilization of conventional cryogenic chip, no heat dissipation plate is needed to combine the heat sink  3  and the semicoductive element  2 . Thus, the dissipation device of the present invention is less costly and the fabrication thereof is less complicated.  
      A thermoelectric heat dissipation device fabricated by the above method is described hereinafter. The construction of the thermoelectric heat dissipation device is shown in FIGS.  2  to  5 , as a preferred embodiment.  
       FIG. 5  shows a thermoelectric heat dissipation device. The device includes a thermoelectric semicondutive element  2 , a base plate  1  for adhering to the semiconductive element  2 , and a heat sink  3  connected to the thermoelectric semiconductive element  2 . The base plate  1  provides a surface to adhere the thermoelectric semiconductive element  2 , as shown in  FIG. 2 . The base plate  1  is made by the material with heat conductivity but without electric conductivity. In the embodiment shown in  FIG. 2 , the base late  1  is preferably made of ceramic material. The base plate  1  is molded in a form of a plate. Thus, two surfaces are provided. The upper surface is utilized to be as an adhering surface for connecting the thermoelectric semiconductive element  2  and be patterned a plurality of conductive lines  41  for electrically connecting the P-N posts  21 ,  22  of the element  2 .  
      The thermoelectric semiconductive element  2  includes a plurality of sets of P-N posts  21 ,  22 . The element  2  is so called a cryogenic chip. For heat change, the P-N posts  21 ,  22  are able to absorb the heat from one end and transfer the heat to the other end under electricity. In a preferred embodiment, the thermoelectric seminconductive element  2  includes a cooling end  23  for adhere to the surface of the base plate  1  and a dissipation end  24 .  
      The heat sink  3 , in a preferred embodiment, is made from material with high heat conductivity but is electrically insulated. In another embodiment, as shown in  FIG. 4 , the heat sink is made from metal with high heat conductivity. When the heat sink  3  is made from metal, the surface  31  for adhering to the thermoelectric semiconductive element  2  should be coated an inert coating  33 , such as anodic coating, for electric insulation.  
      The heat sink  3  described hereinbefore, as shown in  FIG. 4 , can be molded as a construction consisting of surface  31  and fins  32 . Optionally, the heat sink  3  can further includes an upper plate. The surface  31  of the heat sink  3  is able to adhere with the thermoelectric semiconductive element  2 . As shown in  FIG. 4 , a plurality of electric lines  42  are patterned on the surface  31  for electrically connecting with the P-N posts  21 ,  22  of the thermoelectric semiconductive element.  
      The thermoelectric heat dissipation device fabricated by the method describe herein is able to enhance the efficiency of heat dissipation when comparing with the combination of cryogenic chip and heat sink of prior art because the heat sink  3  is directly adhered to the heat dissipation surface  24  of the thermoelectric semiconductive element  2  for heat exchange the heat from the surface  24  to heat sink  3 .  
      While an illustrative and presently preferred embodiment of the invention has been described in detail herein, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.