Patent Publication Number: US-2017350657-A1

Title: Heat spreader with a liquid-vapor separation structure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to cooling technology and more particularly, to a heat spreader with a liquid-vapor separation structure. 
     2. Description of the Related Art 
     With the continuous growing trend of global electronics industry market, many electronic products (such as LED light module, computers and mobile phones, etc . . . ) have become an indispensable part of people&#39;s lives. However, with continuous development of these electronic products, in order to achieve enhanced product performance, the product composition units are easy to produce large amounts of heat during operation. When these product composition units have a certain degree of waste heat accumulated therein, the working efficiency of these electronic products will be lowered, or the lifespan of these electronic products will be shortened. Therefore, most electronic products have heat pipes or heat spreaders (vapor chambers) mounted in their heat-generating units and incorporated with radiation fins or cooling fans to form a cooling system for quick dissipation of waste heat. A heat pipe is one-dimensional and linear structure that transfers heat from one single point to another while a heat spreader (vapor chamber) is a plate that spreads heat from one point to a two-dimensional area. A heat spreader can rapidly and evenly spread out heat energy, accelerating thermal cycle efficiency. Therefore, heat spreaders (vapor chambers) have better thermal performance than heat pipes. Taiwan Patent Publication No. 1476361 discloses a heat spreader and the formation of the wick structure of the heat spreader. According to this design, the heat spreader comprises a bottom panel, a cover panel, a plurality of support projections, a wick structure and a working fluid. The cover panel is closed on the bottom panel and sealed such that an accommodation chamber is defined in between the cover panel and the bottom panel. The support projections are directly formed on the inner wall of the bottom panel or cover panel. The wick structure is coated on the surface of each support projection, the inside wall of the bottom panel and the inside wall of the cover panel. The working fluid is filled in the accommodation chamber to enhance the thermal conducting efficiency and speed of the heat spreader. 
     Although the heat spreader uses the support projections to enhance its supporting strength, the arrangement of the support projections makes the wick structure to exhibit an undulating configuration. During thermal cycling, the working fluid must go through apertures in the wick structure in between the support projections. This undulating structure will affect the reflux rate of the working fluid. Further, the working fluid flows in the accommodation chamber in a liquid-vapor coexistence manner. The flowing of the liquid phase and vapor phase of the working fluid in different directions may also cause a reduction in the mass flux during thermal cycling, further affecting the cooling effect. 
     Further, because the support projections of the aforesaid prior art heat transfer respectively consist of two solid semi-spheres of unequal radius and arranged spaced away from one another, if the heat spreader is mounted in a space that needs to bear a load or tends to be compressed, the stress point will be focused on the top side of the semi-spheres, thus, if the heat spreader is compressed, the pressure cannot be evenly distributed in all directions, leading to structural damage. Therefore, an improvement on the structural support of a heat spreader is desired. 
     SUMMARY OF THE INVENTION 
     The present invention has been accomplished under the circumstances in view. It is the main object of the present invention to provide a heat spreader with a liquid-vapor separation structure, which has multiple vapor passages and at least one liquid passage arranged therein to constrain the vapor phase and liquid phase of a working fluid to flow in different passages, increasing the mass flux of the working fluid in the vapor-liquid circulation system to achieve better heat dissipation performance. 
     It is another object of the present invention to provide a heat spreader with a liquid-vapor separation structure, which has multiple spacer members arranged therein and abutted between at least one first panel and a second panel thereof to form a strong support structure, achieving a better supporting effect. 
     To achieve these and other objects of the present invention, a heat spreader with a liquid-vapor separation structure comprises at least one first panel, a second panel, a plurality of spacer members, at least one piece of first wick, and a working fluid. The second panel bonded with the at least one first panel, defining with the at least one first panel at least one enclosed accommodation chamber therebetween. The spacer members are abutted between the at least one first panel and the second panel and arranged spaced apart from one another in the at least one enclosed accommodation chamber, defining a plurality of vapor passages and at least one liquid passage. The spacer members divide the at least one enclosed accommodation chamber into a heat-absorbing zone and condensing zone. The heat-absorbing zone and the condensing zone are disposed in communication with each other through the vapor passages and the at least one liquid passage. The at least one piece of first wick material has a part thereof disposed in the at least one liquid passage, and the other part thereof respectively disposed in the heat-absorbing zone and the condensing zone. The working fluid is filled in the at least one enclosed accommodation chamber. 
     Thus, the arrangement of the multiple vapor passages and the at least one liquid passage in the heat spreader effectively overcomes the problem of low mass flux of working fluid in the prior art designs due to vapor-liquid co-existence, achieving better working fluid cycle efficiency and enhancing heat dissipation performance. 
     Further, the spacer members are elongated members stopped between the first panel and the second panel. When compared to the support structure consisting of two solid semi-spheres of unequal radius of the prior art design, the invention provides a better supporting effect. 
     Other advantages and features of the present invention will be fully understood by reference to the following specification in conjunction with the accompanying drawings, in which like reference signs denote like components of structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded view of a heat spreader in accordance with a first embodiment of the present invention. 
         FIG. 2  is a front view of the first embodiment of the present invention, illustrating the internal structure of the heat spreader. 
         FIG. 3  is a longitudinal sectional view taken along line  3 - 3  of  FIG. 2 . 
         FIG. 4  is a cross sectional view of the heat spreader in accordance with the first embodiment of the present invention. 
         FIG. 5  is a front view illustrating the internal structure of a heat spreader in accordance with a second embodiment of the present invention. 
         FIG. 6  is a front view illustrating the internal structure of a heat spreader in accordance with a third embodiment of the present invention. 
         FIG. 7  is an exploded view of a part of the heat spreader in accordance with the third embodiment of the present invention. 
         FIG. 8  is a schematic side view of the heat spreader in accordance with the third embodiment of the present invention. 
         FIG. 9  is an exploded view of a heat spreader in accordance with a fourth embodiment of the present invention. 
         FIG. 10  illustrates cylindrical support blocks arranged in the heat-absorbing zone and the condensing zone of heat spreader in accordance with the fourth embodiment of the present invention. 
         FIG. 11  illustrates long columnar support blocks arranged in the heat-absorbing zone of heat spreader in accordance with the fourth embodiment of the present invention. 
         FIG. 12  illustrates long columnar support blocks arranged in the heat-absorbing zone and the condensing zone of heat spreader in accordance with the fourth embodiment of the present invention. 
         FIG. 13  is an exploded view of a heat spreader in accordance with a fifth embodiment of the present invention. 
         FIG. 14  is an exploded view of an alternate form of the heat spreader in accordance with the fifth embodiment of the present invention, illustrating the second wick material disposed in the second panel within the heat-absorbing zone. 
         FIG. 15  is an exploded view of another alternate form of the heat spreader in accordance with the fifth embodiment of the present invention, illustrating the second wick material disposed in the second panel within the heat-absorbing zone and the condensing zone. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1-4 , a heat spreader with a liquid-vapor separation structure in accordance with a first embodiment of the present invention is shown. The heat spreader  10  comprises at least one first panel  11 , a second panel  12 , a plurality of spacer members  13 , at least one piece of first wick material  14  and a working fluid (not shown). 
     The at least one first panel  11  is bonded to the second panel  12 . In this first embodiment, the number of the at least one first panel  11  is 1. Further, the first panel  11  and the second panel  12  define therebetween at least one enclosed accommodation chamber  121 . In this first embodiment, the number of the at least one accommodation chamber  121  is 1. Further, at least one vapor discharge tube  19  is disposed in the connection area between the first panel  11  and the second panel  12 . In this first embodiment, the number of the at least one vapor discharge tube  19  is 1. The vapor discharge tube  19  has one end thereof disposed in communication with the accommodation chamber  121 , and an opposite end thereof extended out of the heat spreader  10  and blocked. 
     The multiple spacer members  13  are disposed inside the accommodation chamber  121  and abutted between the first panel  11  and the second panel  12 . Further, the spacer members  13  are arranged spaced apart from one another, thereby defining a plurality of vapor passages  141  and at least one liquid passage  142 . In this first embodiment, the number of the at least one liquid passage  142  is 2. Further, the multiple spacer members  13  device the accommodation chamber  121  into a heat-absorbing zone H and a condensing zone C. The heat-absorbing zone H and the condensing zone C are disposed in communication with each other by means of the multiple vapor passages  141  and the two liquid passages  142 . Further, a heat-insulating zone A is defined in the accommodation chamber  121  between the heat-absorbing zone H and the condensing zone C. The multiple spacer members  13  are mounted in the heat-insulating zone A. In the present first embodiment of the present invention, the multiple spacer members  13  have an elongated shape; the multiple vapor passages  141  and the two liquid passages  142  respectively exhibit an elongated shape (see  FIGS. 1, 2 and 4 ). 
     The at least one piece of first wick material  14  has a part thereof mounted in the two liquid passages  142 . In this first embodiment of the present invention, the number of the at least one piece of first wick material  14  is 2. The other part of these two pieces of first wick material  14  is disposed in the heat-absorbing zone H and the condensing zone C. In this first embodiment of the present invention, these two pieces of first wick material  14  have an elongated shape. Further, these two pieces of first wick material  14  fill up the liquid passages  142 . These two pieces of first wick material  14  can be fiber tows, copper powder or copper mesh (not shown). In this first embodiment of the present invention, these two pieces of first wick material  14  are fiber tows (see  FIGS. 1 and 2 ) 
     The working fluid is filled in the accommodation chamber  121 . Since technical filed of the working fluid is obvious to any person skilled in the art and difficult to display in the figure, it is unnecessary to repeat them here. 
     After understanding the structural details of this first embodiment of the present invention, the application of this first embodiment is explained hereinafter. 
     As illustrated in  FIGS. 1-4 , when the heat spreader  10  is at work, the heat-absorbing zone H transfers heat energy to the accommodation chamber  121 , causing the working fluid in the two pieces of first wick material  14  to be vaporized into vapor phase. The working fluid will then go through the multiple vapor passages  141  in between the multiple spacer members  13  in the form of vapor phase, and then diffuses into the condensing zone C. When reached the condensing zone C, the working fluid can be reduced to liquid phase and adhered to the condensing zone C, and then guided by the two fiber tows of the first wick material  14  through the two liquid passages  142  between the condensing zone C and the heat-absorbing zone H to flow back to the heat-absorbing zone H. The multiple vapor passages  141  and the two liquid passages  142  constrain the vapor phase and liquid phase working fluid to flow in different passages, increasing the mass flux of the working fluid in the vapor-liquid circulation system. The multiple spacer members  13  are abutted between the first panel  11  and second panel  12  of the heat spreader  10  to form a sturdy support structure, achieving a better supporting effect. The use of the two elongated pieces of first wick material  14  in the heat spreader  10  effectively accelerates the circulation of the working fluid in the heat spreader  10 . Physically, using fiber tows for the two pieces of first wick material  14  achieves more mass flux of the working fluid than that using sintered copper powder and copper mesh. 
     Accordingly, by the above-described first embodiment of the present invention, it is apparent that the arrangement of the multiple vapor passages  141  and the two liquid passages  142  in the heat spreader  10  effectively overcomes the problem of low mass flux of working fluid in the prior art designs due to vapor-liquid co-existence, achieving better working fluid cycle efficiency and enhancing heat dissipation performance. 
     As stated above, the multiple spacer members  13  are elongated members abutted between the first panel  11  and second panel  12  of the heat spreader  10 . When compared to the support structure consisting of two solid semi-spheres of unequal radius of the prior art design, the invention provides a better supporting effect. 
     Referring to  FIG. 5 , a heat spreader  20  in accordance with a second embodiment of the present invention is shown. This second embodiment is substantially similar to the aforesaid first embodiment with the exceptions as follows: 
     The second panel  22  has a second wick material  28  sintered thereto. This second wick material  28  can be disposed in the second panel  22  within the heat-absorbing zone H 2  and/or the condensing zone C 2 . In this second embodiment, the two pieces of first wick material  24  are disposed in contact with the second wick material  28 . 
     The second wick material  28  can be selected from copper powder or copper mesh. In this second embodiment, the second wick material  28  is a copper mesh. 
     In this second embodiment, a respective certain area of the second wick material  28  is respectively sintered to the heat-absorbing zone H 2  and the condensing zone C 2  in the second panel  22  of the heat spreader  20 , enabling the heat-absorbing zone H 2  to have a relatively higher working fluid carrying capacity. Further, the second wick material  28  effectively and evenly carries the working fluid, enhancing the evapotranspiration efficiency of the working fluid. Further, the arrangement of the second wick material  28  in the condensing zone C 2  inside the second panel  22  significantly increases the working fluid carrying capacity of the condensing zone C 2 , improving the reflux efficiency of the working fluid during cycling. The other structural features of this second embodiment and the effect this second embodiment can achieve are same as the aforesaid first embodiment, and thus, it is unnecessary to repeat them here. 
     Referring to  FIGS. 6-8 , a heat spreader  30  in accordance with a third embodiment of the present invention is shown. This third embodiment is substantially similar to the aforesaid first embodiment with the exceptions as follows: 
     The second panel  32  further comprises at least one recessed portion  322  located in the condensing zone C 3 . In this third embodiment, the number of the at least one recessed portion  322  is 2; the second panel  32  further has a third wick material  38  sintered thereto and located at a bottom side of each of the two recessed portion  322 . Further, the third wick material  38  is connected with the first wick material  34 . Further, the height of the two recessed portions  322  is greater than the height from the at least one first panel  31  to the second panel  32  (see  FIG. 8 ). In this third embodiment, the number of the at least one first panel  31  is 2. These two first panels  31  are bonded to the second panel  32 . Further, two enclosed accommodation chambers  321  are defined between the two first panels  31  and the second panel  32 . Each accommodation chamber  321  has arranged therein a plurality of spacer members  33 , a heat-absorbing zone H 3 , a condensing zone C 3 , a plurality of vapor passages  341 , two liquid passages  342 , two pieces of first wick material  38  and a working fluid (not shown). 
     The third wick material  38  can be selected from copper powder or copper mesh. In this third embodiment, the third wick material  38  is made from copper mesh. 
     In this third embodiment, the added structure of the two recessed portions  322  of the heat spreader  30  increase the working fluid storage capacity of the condensing zone C 3 ; the two pieces of first wick material  34  are used to guide the working fluid from the condensing zone C 3  back to the heat-absorbing zone H 3 . Further, changing the number of the component parts of the heat spreader  30  can relatively changing the cooling efficiency. The other structural features of this third embodiment and the effect this third embodiment can achieve are same as the aforesaid first embodiment, and thus, it is unnecessary to repeat them here. 
     Referring to  FIG. 9 , a heat spreader  40  in accordance with a fourth embodiment of the present invention is shown. This fourth embodiment is substantially similar to the aforesaid first embodiment with the exceptions as follows: 
     The second panel  42  further comprises a plurality of support blocks  49  corresponding to the heat-absorbing zone H 4  and/or the condensing zone C 4 . In this fourth embodiment, the support blocks  49  are mounted in the second panel  42  within the heat-absorbing zone H 4 . Further, these support blocks  49  are cylindrical blocks. Further, the number of the at least one piece of first wick material  44  in this fourth embodiment is 4. These support blocks  49  are stopped against the first panel  41 . Further, these support blocks  49  are respectively arranged at two opposite lateral sides of the first wick material  44  within the heat-absorbing zone H 4  to keep the first wick material  44  in position. Further; the support blocks  49  can aligned with one another, or arranged in staggered rows. In this fourth embodiment, the support blocks  49  are aligned with one another. Further, the support blocks  49  are respectively arranged in alignment with the spacer members  43 , forming a plurality of equally spaced support member sets  45 . Further, except the aforesaid configuration, the support blocks  49  can also be arranged in the second panel  42  corresponding to the heat-absorbing zone H 4  and the condensing zone C 4  (see  FIG. 10 ) and, the support blocks  49  can be configured to have a long columnar shape (see  FIGS. 11 and 12 ). 
     In this fourth embodiment, the support blocks  49  of the heat spreader  40  can be arranged in the second panel  42  corresponding to the heat-absorbing zone H 4  and/or the condensing zone C 4  to effectively enhance the structural strength of heat spreader  40 . The other structural features of this fourth embodiment and the effect this fourth embodiment can achieve are same as the aforesaid first embodiment, and thus, it is unnecessary to repeat them here. 
     Referring to  FIG. 13 , a heat spreader  50  in accordance with a fifth embodiment of the present invention is shown. This fifth embodiment is substantially similar to the aforesaid first embodiment with the exceptions as follows: 
     The second panel  52  has multiple support blocks  59  arranged therein corresponding to the heat-absorbing zone H 5  and/or the condensing zone C 5 . In this fifth embodiment, the support blocks  59  are cylindrical blocks arranged in the second panel  52  within the heat-absorbing zone H 5 ; the number of the at least one piece of first wick material  54  is 4. Further, the support blocks  59  are stopped against the first panel  51 , and disposed at two opposite lateral sides of the multiple pieces of first wick material  54  within the heat-absorbing zone H 5  to hold the multiple pieces of first wick material  54  in position. These support blocks  59  can aligned with one another, or arranged in staggered rows. In this fifth embodiment, the support blocks  59  are aligned with one another. Further, the support blocks  59  are respectively arranged in alignment with the spacer members  53 , forming a plurality of equally spaced support member set  55 . 
     Further, except the aforesaid configuration, the support blocks  59  can also be arranged in the second panel  52  corresponding to the heat-absorbing zone H 5  and the condensing zone C 5 . Further, the support blocks  59  can be configured to have a long columnar shape (not shown). 
     The heat spreader  50  in accordance with this fifth embodiment of the present invention further comprises a second wick material  58  located in the second panel  52  corresponding to the heat-absorbing zone H 5  and/or the condensing zone C 5 , and disposed in contact with the at least one piece of first wick material  54 . In this fifth embodiment, the second wick material  58  is disposed in the second panel  52  within the condensing zone C 5 . Further, the number of the at least one piece of first wick material  54  is 4. Except the configuration described above, the second wick material  58  can be simply disposed in the second panel  52  within the condensing zone C 5  (see  FIG. 14 ). Alternatively, the second wick material  58  can be disposed in the second panel  52  within the heat-absorbing zone H 5  and the condensing zone C 5  (see  FIG. 15 ). 
     The structural arrangement of this fifth embodiment significantly increases the working fluid carrying capacity of the heat-absorbing zone H 5  and the condensing zone C 5  while maintaining the structural strength of heat-absorbing zone H 5  and condensing zone C 5  of the heat spreader  50 . The other structural features of this fifth embodiment and the effect this fifth embodiment can achieve are same as the aforesaid first embodiment, and thus, it is unnecessary to repeat them here. 
     Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.