Patent Publication Number: US-11641725-B2

Title: Heat dissipator and communications device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/685,019, filed on Nov. 15, 2019, which is a continuation of International Application No. PCT/CN2018/081169, filed on Mar. 29, 2018, which claims priority to Chinese Patent Application No. 201710349131.4, filed on May 17, 2017. All of the aforementioned patent applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     This application relates to a heat dissipation apparatus, and in particular, to a heat dissipator and a communications device. 
     BACKGROUND 
     With continuous increasing of power of a heat emitting apparatus (for example, a chip) in a communications device, the heat emitting apparatus generates an increasing amount of heat in a running process. Therefore, an increasingly strict requirement is posed on a heat dissipator configured to perform heat dissipation on the heat emitting apparatus. Currently, a heat dissipator can be mainly classified into a micro channel heat dissipator and a jet flow heat dissipator that combines a jet flow technology and a micro channel. 
     However, heat dissipation efficiency of the heat dissipator is relatively low because of a structure of the heat dissipator. Therefore, how to improve heat dissipation efficiency of the jet flow heat dissipator is a problem that urgently needs to be resolved currently. 
     SUMMARY 
     Embodiments of this application provide a heat dissipator and a communications device, so as to improve heat dissipation efficiency of the heat dissipator. 
     To achieve the foregoing objective, the following technical solutions are used in the embodiments of this application. 
     According to a first aspect, a heat dissipator is disclosed. The heat dissipator includes a cover plate, an orifice plate, and a base plate that are stacked in sequence. A distribution cavity is disposed between the orifice plate and the cover plate, a heat exchange cavity is disposed between the orifice plate and the base plate, and through holes are disposed on the orifice plate, so that the distribution cavity communicates with the heat exchange cavity by using the through holes. A plurality of pin fins facing the orifice plate are disposed on a surface of the base plate in the heat exchange cavity, gaps between the plurality of pin fins constitute a fluid passage, and the pin fins include a combination pin fin and a flow guiding pin fin. The combination pin fin is in contact with the orifice plate, and the flow guiding pin fin corresponds to the through hole and has a gap with the through hole. 
     In the heat dissipator provided in this embodiment of this application, there is the gap between the flow guiding pin fin and the through hole of the orifice plate, and the combination pin fin is separately in contact with the base plate and the orifice plate. Therefore, when heat dissipation is performed on the heat dissipator, after being jetted into the gap between the flow guiding pin fin and the through hole, a fluid whose temperature is less than a temperature of a heat emitting apparatus enters a fluid passage constituted by the combination pin fin and the flow guiding pin fin, to participate in heat exchanging. In this way, a quantity of fluids that directly flow out of the heat exchange cavity without passing through the fluid passage constituted by the combination pin fin and the flow guiding pin fin is reduced, and fluid utilization is increased. Therefore, the heat dissipator provided in this embodiment of this application can improve heat dissipation efficiency of the heat dissipator. 
     It should be noted that, to prevent the through hole from being blocked, the flow guiding pin fin may alternatively not be disposed on the surface of the base plate in the heat exchange cavity. In other words, the pin fins can include the combination pin fin being in contact with the orifice plate. 
     In a possible design, the gap between the flow guiding pin fin and the through hole is greater than or equal to 0.1 mm. In other words, a difference between a height of the combination pin fin and a height of the flow guiding pin fin is greater than or equal to 0.1 mm. In this way, at a location corresponding to the through hole, sufficient space may be reserved for a fluid to enter the heat exchange cavity, so that the fluid can be smoothly jetted into the fluid passage constituted by the combination pin fin and the flow guiding pin fin. In addition, after the fluid passes by a distance greater than or equal to 0.1 mm, a speed of the fluid may be relatively slowed down, so as to reduce impact on the flow guiding pin fin, and avoid abrasion of the flow guiding pin fin that is caused by long-term impact of a high-speed fluid. 
     In a possible design, an elastic gasket may be disposed between the combination pin fin and the orifice plate, so that the combination pin fin is in contact with the orifice plate by using the elastic gasket. After the heat dissipator is manufactured, the elastic gasket elastically deforms under pressure of the combination pin fin and the orifice plate, so that the elastic gasket is separately in close contact with the combination pin fin and the orifice plate, thereby compensating for deficiency that the combination pin fin is not in contact with the orifice plate because of impact of processing precision. 
     In a possible design, a shape of a cross section of each combination pin fin is a square, a circle, or a rhombus. 
     In a possible design, a shape of a cross section of each flow guiding pin fin may also be a square, a circle, or a rhombus. 
     The square, the circle, or the rhombus is symmetrical, so as to help design and process the heat dissipator, and help implement industrialized production of the heat dissipator. However, these examples are of course non-limiting and the shape of the cross section of each combination pin fin and/or each flow guiding pin fin may include any shape. 
     In a possible design, a feature size of each combination pin fin is less than or equal to 1 mm, and the feature size=4×an area of a cross section of the combination pin fin/a perimeter of the cross section of the combination pin fin. 
     In a possible design, a ratio of a height to the feature size of each combination pin fin is greater than or equal to 5. 
     In a possible design, a ratio of a gap between two adjacent combination pin fins to each of feature sizes of the combination pin fins ranges from 1:0.9 to 1:1.1. 
     In a possible design, a feature size of each flow guiding pin fin is less than or equal to 1 mm, and the feature size=4×an area of a cross section of the flow guiding pin fin/a perimeter of the cross section of the flow guiding pin fin. 
     In a possible design, a ratio of a height to the feature size of each flow guiding pin fin is greater than or equal to 5. 
     In a possible design, a ratio of a gap between two adjacent flow guiding pin fins to each of feature sizes of the combination pin fins ranges from 1:0.9 to 1:1.1. 
     Because a size and distribution density of the combination pin fin and those of the flow guiding pin fin fall within the foregoing value range, a quantity of combination pin fins and a quantity of flow guiding pin fins per unit volume may be increased while it is ensured that a fluid can smoothly flow, so as to increase a contact area between the fluid and the combination pin fin and a contact area between the fluid and the flow guiding pin fin, and further increase heat dissipation efficiency of the heat dissipator. 
     It should be noted that a feature size is four times of a ratio of an area of a cross section of a pin fin to a perimeter of the cross section of the pin fin. For example, when a shape of the cross section of the pin fin (e.g., the combination pin fin and/or the flow guiding pin fin) is a circle, a feature size of the pin fin=4πR 2 /2πR=2R. In other words, the feature size of the circle is a diameter D of the circle, R is a radius of the circle, and D is the diameter of the circle. When a shape of the cross section of the pin fin (e.g., the combination pin fin and/or the flow guiding pin fin) is a rectangle, a feature size of the rectangle=4AB/2(A+B), where A is a width of the rectangle, and B is a length of the rectangle. 
     In a possible design, the base plate, the combination pin fin, and the flow guiding pin fin may be made of aluminum alloy, brass, or red copper by using an integrated forming technology. In a case of same fluid utilization, a higher heat dissipation coefficient of a material of which the base plate, the combination pin fin, or the flow guiding pin fin is made leads to higher heat dissipation efficiency of the heat dissipator. Therefore, when the base plate, the combination pin fin, and the flow guiding pin fin are made of aluminum alloy, brass, or red copper having a relatively high heat dissipation coefficient, heat dissipation efficiency of the heat dissipator can be further improved 
     In a possible design, a diameter of the through hole ranges from 0.2 mm to 2.0 mm. In this way, a high-speed jetting stream can be formed after a fluid flows through the through hole, so as to increase a quantity of fluids that are jetted into the bottom of the fluid passage, properly reduce working pressure of the distribution cavity, and improve security of the heat dissipator. 
     In a possible design, the heat dissipator may be classified into a single-phase heat dissipator and a phase-change heat dissipator based on a heat dissipation manner. No phase change occurs on a fluid (which is always in a liquid state) of the single-phase heat dissipator in a heat exchange process, and a phase change occurs on a heat dissipation fluid (which is gasified from a liquid state to a gas state) of the phase-change heat dissipator in a heat exchange process. 
     Alternatively, the heat dissipator may be classified into a distributed heat dissipator and a single-pass heat dissipator based on a flow manner of a fluid. 
     In a possible design, when the heat dissipator is the distributed heat dissipator, partition plates that face the cover plate and that are in contact with the cover plate are disposed on a surface of the orifice plate in the distribution cavity of the heat dissipator, the partition plates partition the distribution cavity into a plurality of inflow cavities and a plurality of outflow cavities, and the inflow cavities and the outflow cavities separately communicate with the heat exchange cavity by using the through holes; and the inflow cavities are provided with a fluid inlet, and the outflow cavities are provided with a fluid outlet. After the fluid is jetted from one inflow cavity into the heat exchange cavity by using the through hole for heat exchanging, the fluid flows from the heat exchange cavity to an outflow cavity adjacent to the inflow cavity by using the through hole, so as to shorten a path through which the fluid flows in the fluid passage constituted by the combination pin fin and the flow guiding pin fin. This is especially applied to the phase-change heat dissipator, and the distributed heat dissipator can reduce a possibility that the heat exchange cavity is dried out. In addition, because there are a plurality of outflow cavities, there are also a plurality of through holes communicating with the outflow cavities, so that a fluid obtained after the heat exchanging can flow into the outflow cavities by using the plurality of through holes, thereby reducing internal pressure of the heat exchange cavity. 
     In a possible design, the partition plates may be in a sawtooth shape or a spiral shape. Correspondingly, the partition plates partition the distribution cavity into a plurality of sawtooth inflow cavities and a plurality of sawtooth outflow cavities, or partition the distribution cavity into a plurality of spiral inflow cavities and a plurality of spiral outflow cavities. Compared with the spiral partition plate, the sawtooth partition plate has a simple structure, and pressure of the inflow cavities is evenly distributed, so that a heat dissipator having a sawtooth partition plate is more practical. 
     In a possible design, the inflow cavities and the outflow cavities are alternately distributed. In this way, a path through which a fluid flows in the fluid passage constituted by the combination pin fin and the flow guiding pin fin can be further shortened. 
     In a possible design, a diameter of a through hole communicating with the inflow cavity is less than a diameter of a through hole communicating with the outflow cavity. A through hole that has a smaller diameter and that communicates with the inflow cavity may increase a fluid speed when a fluid is jetted into the heat exchange cavity, so that the fluid can be jetted into the bottom of the heat exchange cavity by using a gap between flow guiding pin fins. A through hole that has a larger diameter and that communicates with the outflow cavity helps a fluid obtained after heat exchanging to be discharged from the heat exchange cavity, so as to reduce internal pressure of the heat exchange cavity. 
     In a possible design, diameters of through holes communicating with the outflow cavities gradually increase in a direction from approaching the fluid inlet to away from the fluid inlet. This is because a quantity of fluids obtained after heat exchanging gradually increases in the heat exchange cavity in the direction from approaching the fluid inlet to away from the fluid inlet, and the diameters of the through holes communicating with the outflow cavities gradually increase, so as to better help the fluids obtained after the heat exchanging to be discharged from the heat exchange cavity, and further reduce internal pressure of the heat exchange cavity. 
     In a possible design, a height of a flow guiding pin fin corresponding to the inflow cavity is greater than a height of a flow guiding pin fin corresponding to the outflow cavity. In this way, this better helps fluids obtained after heat exchanging aggregate at a location of a through hole communicating with the outflow cavity, so as to help the fluids obtained after the heat exchanging to be discharged from the heat exchange cavity, and further reduce internal pressure of the heat exchange cavity. 
     In a possible design, when the heat dissipator is the single-pass heat dissipator, a distribution cavity of the heat dissipator is provided with a fluid inlet, and a heat exchange cavity of the heat dissipator is provided with a fluid outlet. The single-pass heat dissipator has a simple structure, and implements regular flow of a fluid. 
     In a possible design, diameters of through holes gradually decrease in a direction from approaching the fluid inlet to away from the fluid inlet. This is because a quantity of fluids obtained after heat exchanging gradually increases in the heat exchange cavity in the direction from approaching the fluid inlet to away from the fluid inlet, and the diameters of the through holes gradually decrease, so that the fluids obtained after the heat exchanging can be prevented from reversely overflowing to the distribution cavity by using the through holes. 
     According to a second aspect, a communications device is disclosed. The communications device includes a heat emitting apparatus and the heat dissipator in the foregoing embodiment, and a base plate of the heat dissipator is in contact with the heat emitting apparatus. 
     In the heat dissipator in the communications device provided in this embodiment of this application, there is the gap between the flow guiding pin fin and the through hole of the orifice plate, and the combination pin fin is separately in contact with the base plate and the orifice plate. Therefore, when heat dissipation is performed on the heat dissipator, after being jetted into the gap between the flow guiding pin fin and the through hole, a fluid whose temperature is less than a temperature of a heat emitting apparatus enters a fluid passage constituted by the combination pin fin and the flow guiding pin fin, to participate in heat exchanging. In this way, a quantity of fluids that directly flow out of the heat exchange cavity without passing through the fluid passage constituted by the combination pin fin and the flow guiding pin fin is reduced, and fluid utilization is increased. Therefore, the communications device provided in this embodiment of this application can improve heat dissipation efficiency of the communications device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic structural diagram of a heat dissipator according to an embodiment of this application; 
         FIG.  2    is an exploded diagram of  FIG.  1   ; 
         FIG.  3    is a sectional view of  FIG.  1    in an A-A direction; 
         FIG.  4   a    is a schematic structural diagram of an orifice plate of a heat dissipator according to an embodiment of this application; 
         FIG.  4   b    is a schematic structural diagram in another form of an orifice plate of a heat dissipator according to an embodiment of this application, where through holes are omitted in this figure; 
         FIG.  5    is a schematic structural diagram of a combination pin fin of the heat dissipator in  FIG.  1   ; 
         FIG.  6    is a schematic structural diagram in another form of a heat dissipator according to an embodiment of this application; 
         FIG.  7    is an exploded diagram of  FIG.  6   ; and 
         FIG.  8    is a schematic structural diagram of an orifice plate of the heat dissipator in  FIG.  6   . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following clearly describes the technical solutions in the embodiments of this application with reference to the accompanying drawings in the embodiments of this application. 
     An embodiment of this application provides a heat dissipator. Referring to  FIG.  1    to  FIG.  8   , the heat dissipator includes a cover plate  10 , an orifice plate  20 , and a base plate  30  that are stacked in sequence. A distribution cavity  40  is disposed between the cover plate  10  and the orifice plate  20 , and a heat exchange cavity  50  is disposed between the orifice plate  20  and the base plate  30 . Through holes  21  through which the distribution cavity  40  communicates with the heat exchange cavity  50  are disposed on the orifice plate  20 . A plurality of pin fins  61  facing the orifice plate  20  are disposed on a surface of the base plate  30  in the heat exchange cavity  50 , and gaps between the plurality of pin fins  61  constitute a fluid passage. As shown in  FIG.  3   , the pin fins  61  include a combination pin fin  62  in contact with the orifice plate  20 , and a flow guiding pin fin  63  that corresponds to the through hole  21  and that has a gap with the through hole  21 . 
     To form the distribution cavity  40  and the heat exchange cavity  50 , for example, as shown in  FIG.  1    to  FIG.  3   , grooves are respectively disposed on an upper surface and a lower surface of the orifice plate  20 . After the cover plate  10 , the orifice plate  20 , and the base plate  30  are stacked and welded together, the cover plate  10  and the base plate  30  respectively seal openings of the upper and lower grooves (disposed on the upper surface and the lower surface of the orifice plate  20 ), so that space in the groove on the upper surface of the orifice plate  20  can be used as the distribution cavity  40 , and space in the groove on the lower surface of the orifice plate  20  can be used as the heat exchange cavity  50 . 
     In the heat dissipator provided in this embodiment of this application, there is the gap between the flow guiding pin fin  63  and the through hole  21  of the orifice plate  20 , and the combination pin fin  62  is separately in contact with the base plate  30  and the orifice plate  20 . Therefore, when heat dissipation is performed on the heat dissipator, after being jetted into the gap between the flow guiding pin fin  63  and the through hole  21 , a fluid, whose temperature is less than a temperature of a heat emitting apparatus, enters a fluid passage constituted by the combination pin fin  62  and the flow guiding pin fin  63 , to participate in heat exchanging. In this way, a quantity of fluids that directly flows out of the heat exchange cavity  50  without passing through the fluid passage constituted by the combination pin fin  62  and the flow guiding pin fin  63  is reduced, and fluid utilization is increased. Therefore, compared with the prior art, the heat dissipator provided in this embodiment of this application can improve heat dissipation efficiency of the heat dissipator. 
     It should be noted that, to prevent the through hole  21  from being blocked, the flow guiding pin fin  63  may alternatively not be disposed on the surface of the base plate  30  in the heat exchange cavity  50 . In other words, the pin fins  61  include the combination pin fins  62  in contact with the orifice plate  20 . 
     In the heat dissipator, there are a plurality of through holes  21 , a plurality of combination pin fins  62 , and a plurality of flow guiding pin fins  63 . It should be noted herein that, although there are a plurality of through holes  21  and a plurality of flow guiding pin fins  63 , it does not mean that the through holes  21  are in a one-to-one correspondence with the flow guiding pin fins  63 . In other words, one through hole  21  may correspond to one flow guiding pin fin  63 , or may correspond to a plurality of flow guiding pin fins  63 . Of course, there examples are not limited herein. It should be further noted that, because a diameter of the through hole  21  is usually greater than a diameter of the flow guiding pin fin  63 , one flow guiding pin fin  63  usually does not correspond to a plurality of through holes  21 . 
     To enable a fluid to be smoothly jetted into the heat exchange cavity  50 , the gap between the flow guiding pin fin  63  and the through hole  21  needs to be greater than or equal to 0.1 mm. For example, the gap between the flow guiding pin fin  63  and the through hole  21  ranges from 0.5 mm to 2.0 mm. In other words, a difference between a height of the combination pin fin  62  and a height of the flow guiding pin fin  63  needs to be greater than or equal to 0.1 mm. In this way, at a location corresponding to the through hole  21 , sufficient space may be reserved for a fluid to enter the heat exchange cavity  50 , so that the fluid can be smoothly jetted into the fluid passage constituted by the combination pin fin  62  and the flow guiding pin fin  63 . In addition, after the fluid passes by a distance greater than or equal to 0.1 mm, a speed of the fluid may be relatively slowed down, so as to reduce impact on the flow guiding pin fin  63 , and avoid abrasion of the flow guiding pin fin  63  that is caused by long-term impact of a high-speed fluid. 
     In a process of manufacturing the heat dissipator, the combination pin fin  62  may not be in contact with the orifice plate  20  because of impact of actual processing precision, and consequently a gap between the combination pin fin  62  and the orifice plate  20  is caused. To avoid such a problem, referring to  FIG.  5   , an elastic gasket  64  may be disposed between the combination pin fin  62  and the orifice plate  20 , so that the combination pin fin  62  is in contact with the orifice plate  20  by using the elastic gasket  64 . After the heat dissipator is processed based on a design size, the elastic gasket  64  elastically deforms under pressure of the combination pin fin  62  and the orifice plate  20 , so that the elastic gasket  64  is separately in close contact with the combination pin fin  62  and the orifice plate  20 , thereby compensating for a deficiency that the combination pin fin  62  is not in contact with the orifice plate  20  because of impact of processing precision, further reducing a quantity of fluids that do not pass through the fluid passage but directly flow out of the heat exchange cavity  50 , and increasing fluid utilization and improving heat dissipation efficiency of the heat dissipator. 
     To form the elastic gasket  64 , for example, the elastic gasket  64  may be pasted on a surface of the combination pin fin  62  or the orifice plate  20  by using a binding agent. Certainly, the elastic gasket  64  may alternatively be formed on a surface of the combination pin fin  62  or the orifice plate  20  by using a fluid-like elastic fluid material through dispensing and curing, among other aspects. 
     After the structure of the heat dissipator is understood, the following describes in detail optional parameters of the combination pin fin  62 , the flow guiding pin fin  63 , and the through hole  21  in the heat dissipator. 
     For a shape of the combination pin fin  62  and a shape of the flow guiding pin fin  63 , a shape of a cross section of each combination pin fin  62  may be a square, a circle, or a rhombus, for example. Likewise, a shape of a cross section of each flow guiding pin fin  63  may also be a square, a circle, or a rhombus, for example. The cross section is a section perpendicular to an axis direction of the combination pin fin  62  or the flow guiding pin fin  63 . These shapes are all symmetrical, so as to help design and process the heat dissipator, and help implement industrialized production of the heat dissipator. 
     There may be a plurality of combination manners of the shape of the cross section of the combination pin fin  62  and the shape of the cross section of the flow guiding pin fin  63 . For example, the cross section of the combination pin fin  62  may be in a square shape, and the cross section of the flow guiding pin fin  63  may also be in a square shape. Alternatively, the cross section of the combination pin fin  62  is in a rhombus shape, and the cross section of the flow guiding pin fin  63  is in a square shape. Both the combinations are allowed. However, likewise, considering processing and design convenience and industrialized production, the shape of the cross section of the combination pin fin  62  is the same as the shape of the cross section of the flow guiding pin fin  63 . 
     For a size and distribution density of the combination pin fins  62  and those of the flow guiding pin fins  63 , a feature size of each combination pin fin  62  is less than or equal to 1 mm, a ratio of a height to the feature size of each combination pin fin  62  is greater than or equal to 5, and a ratio of a gap between two adjacent combination pin fins  62  to each of feature sizes of the combination pin fins ranges from 1:0.9 to 1:1.1; likewise, a feature size of each flow guiding pin fin  63  is less than or equal to 1 mm, a ratio of a height to the feature size of each flow guiding pin fin  63  is greater than or equal to 5, and a ratio of a gap between two adjacent flow guiding pin fins  63  to each of feature sizes of the combination pin fins ranges from 1:0.9 to 1:1.1. Because the size and the distribution density of the combination pin fin  62  and those of the flow guiding pin fin  63  fall within the foregoing value range, a quantity of combination pin fins  62  and a quantity of flow guiding pin fins  63  per unit volume may be increased while it is ensured that a fluid can smoothly flow, so as to increase a contact area between the fluid and the combination pin fin  62  and a contact area between the fluid and the flow guiding pin fin  63 , and further increase heat dissipation efficiency of the heat dissipator. 
     It should be noted that a feature size is four times of a ratio of an area of a cross section of a pin fin to a perimeter of the cross section of the pin fin. For example, when a shape of the cross section of the pin fin (the combination pin fin  62  and/or the flow guiding pin fin  63 ) is a circle, a feature size of the pin fin=4πR 2 /2πR=2R. In other words, the feature size of the circle is a diameter D of the circle, R is a radius of the circle, and D is the diameter of the circle. When a shape of the cross section of the pin fin is a rectangle, a feature size of the rectangle=4AB/2(A+B), where A is a width of the rectangle, and B is a length of the rectangle. 
     In addition to fluid utilization, a heat exchange coefficient of a material of which the heat dissipator is made is also one of important factors that affect heat dissipation efficiency of the heat dissipator. Therefore, for a material of which the base plate  30 , the combination pin fin  62 , or the flow guiding pin fin  63  is made, any one of aluminum alloy, brass, or red copper having a relatively high heat exchange coefficient may be selected. Red copper ranks first and brass ranks second in terms of a heat exchange coefficient. A material of which the combination pin fin  62  is made may be the same as or may be different from a material of which the flow guiding pin fin  63  is made. However, for ease of processing, the base plate  30 , the combination pin fin  62 , and the flow guiding pin fin  63  may be made of a same material by using an integrated forming technology. 
     A diameter of the through hole  21  may range from 0.2 mm to 2.0 mm. This is because if the diameter of the through hole  21  is excessively large (e.g., exceeds 2.0 mm), a jetting speed after a fluid passes through the through hole  21  is reduced, and consequently a jetting stream cannot be formed, the fluid cannot reach the bottom of the heat exchange cavity  50  for exchanging, and heat exchange efficiency is reduced. If the diameter is excessively small (e.g., less than 0.2 mm), a fluid requires very high pressure to pass through the through hole  21 , and consequently working pressure of the distribution cavity  40  is increased. Therefore, it is set that the diameter of the through hole  21  ranges from 0.2 mm to 2.0 mm, so that a high-speed jetting stream can be formed after the fluid flows through the through hole  21 , thereby increasing a quantity of fluids that are jetted into the bottom of the fluid passage, properly reducing working pressure of the distribution cavity  40 , and improving security of the heat dissipator. 
     The heat dissipator provided in this embodiment of this application may be classified into a single-phase heat dissipator and a phase-change heat dissipator based on a heat dissipation manner. For the two heat dissipation manners, the structure of the heat dissipator does not need to be changed. A difference between the two heat dissipation manners lies in whether a state of a fluid changes in a heat dissipation process. Specifically, in a heat dissipation process, no phase change occurs on a fluid in a liquid state of the single-phase heat dissipator when the fluid performs heat exchanging with the combination pin fin  62 , the flow guiding pin fin  63 , and the base plate  30 . In other words, the fluid can always be in a liquid state. However, in a heat dissipation process, a phase change occurs on a fluid in a liquid state of the phase-change heat dissipator when the fluid performs heat exchanging with the combination pin fin  62 , the flow guiding pin fin  63 , and the base plate  30 . In other words, the fluid is gasified (or vaporized) to gas. Because a large amount of heat is absorbed in a fluid gasification process, heat dissipation efficiency of the phase-change heat dissipator is higher than that of the single-phase heat dissipator, and is more applicable to heat dissipation of a heat emitting apparatus with high power. 
     The heat dissipator provided in this embodiment of this application may be classified into a distributed heat dissipator and a single-pass heat dissipator based on a flow manner of a fluid. Thus, structures of the two heat dissipators can be different. 
     In the distributed heat dissipator, a flow manner of a fluid is as follows: The fluid flows in from the distribution cavity  40  and flows out of the distribution cavity  40 . Referring to  FIG.  1    to  FIG.  5   , partition plates  22  that face the cover plate  10  and that are in contact with the cover plate  10  are disposed on the surface of the orifice plate  20  in the distribution cavity  40 , the partition plates  22  partition the distribution cavity  40  into a plurality of inflow cavities  41  and a plurality of outflow cavities  42 , and the inflow cavities  41  and the outflow cavities  42  separately communicate with the heat exchange cavity  50  by using the through holes  21 . The inflow cavities  41  are provided with a fluid inlet  43 , and the outflow cavities  42  are provided with a fluid outlet  44 . 
     A process in which heat dissipation is performed on the heat emitting apparatus by using the distributed heat dissipator is as follows: A fluid enters the inflow cavity  41  in the distribution cavity  40  from the fluid inlet  43 , and under internal pressure of the distribution cavity  40 , flows through the through hole  21  communicating with the inflow cavity  41  and then is jetted into the fluid passage constituted by the combination pin fin  62  and the flow guiding pin fin  63 . The fluid performs heat exchanging with the combination pin fin  62 , the flow guiding pin fin  63 , and the base plate  30 . Under internal pressure of the heat exchange cavity  50 , the fluid obtained after the heat exchanging flows out of the heat exchange cavity  50  from the through hole  21  communicating with the outflow cavity  42  and then enters the outflow cavity  42 , and flows out of the fluid outlet  44 . 
     For the distributed heat dissipator, after the fluid is jetted from one inflow cavity  41  into the heat exchange cavity  50  by using the through hole  21  for heat exchanging, the fluid flows from the heat exchange cavity  50  to an outflow cavity  42  adjacent to the inflow cavity  41  by using the through hole  21 , so as to shorten a path through which the fluid flows in the fluid passage constituted by the combination pin fin  62  and the flow guiding pin fin  63 . This is especially applied to the phase-change heat dissipator, and the distributed heat dissipator can reduce a possibility that the heat exchange cavity is dried out. In addition, because there are a plurality of outflow cavities  42 , there are also a plurality of through holes  21  communicating with the outflow cavities  42 , so that a fluid obtained after the heat exchanging can flow into the outflow cavities  42  by using the plurality of through holes  21 , thereby reducing internal pressure of the heat exchange cavity  50 . 
     For example, the partition plates  22  may be in a sawtooth shape. As shown in  FIG.  4   a   , the sawtooth partition plates  22  partition the distribution cavity  40  into a plurality of sawtooth inflow cavities  41  that communicate with each other and a plurality of sawtooth outflow cavities  42  that communicate with each other. Alternatively, the partition plates  22  may be in a spiral shape. As shown in  FIG.  4   b   , the spiral partition plates  22  partition the distribution cavity  40  into a plurality of spiral inflow cavities  41  that communicate with each other and a plurality of spiral outflow cavities  42  that communicate with each other. Compared with the spiral partition plate  22 , the sawtooth partition plate  22  has a simple structure, and pressure of the inflow cavities  41  is evenly distributed, so that a heat dissipator having a sawtooth partition plate  22  is more practical. 
     To further shorten the path through which the fluid flows in the fluid passage constituted by the combination pin fin  62  and the flow guiding pin fin  63 , referring to  FIG.  4   a   , it may be set that the inflow cavities  41  and the outflow cavities  42  are alternately distributed. In this way, the path through which the fluid flows in the fluid passage constituted by the combination pin fin  62  and the flow guiding pin fin  63  can be further shortened. Tests have shown that the setting may basically avoid a dry-out possibility. 
     As shown in  FIG.  4   a   , a diameter of a through hole  21  communicating with the inflow cavity  41  is less than a diameter of a through hole  21  communicating with the outflow cavity  42 . For example, the diameter of the through hole  21  communicating with the inflow cavity  41  may range from 0.2 mm to 0.5 mm, and the diameter of the through hole  21  communicating with the outflow cavity  42  may range from 1.5 mm to 2.0 mm. A through hole  21  that has a smaller diameter and that communicates with the inflow cavity  41  may increase a fluid speed when a fluid is jetted into the heat exchange cavity  50 , so that the fluid can be jetted into the bottom of the heat exchange cavity  50  by using a gap between flow guiding pin fins  63 . A through hole  21  that has a larger diameter and that communicates with the outflow cavity  42  helps a fluid obtained after heat exchanging to be discharged from the heat exchange cavity  50 , so as to reduce internal pressure of the heat exchange cavity  50 . 
     In the distributed heat dissipator, there is at least one fluid inlet  43 , and the fluid inlet  43  may be disposed on a side surface of the inflow cavity  41 . For example, it is assumed that the inflow cavity  41  includes a plurality of side surfaces. When there is one fluid inlet  43 , the fluid inlet  43  is located on one side surface of the inflow cavity  41 . However, when there are a plurality of fluid inlets  43 , the plurality of fluid inlets  43  may be located on a same side surface of the inflow cavity  41 , or may be located on different side surfaces of the inflow cavity  41 . 
     Likewise, there is at least one fluid outlet  44 , and the fluid outlet  44  may be disposed on a side surface of the outflow cavity  42 . For example, it is assumed that the outflow cavity  42  includes a plurality of side surfaces. When there is one fluid outlet  44 , the fluid outlet  44  is located on one side surface of the outflow cavity  42 . However, when there are a plurality of fluid outlets  44 , the plurality of fluid outlets  44  may be located on a same side surface of the outflow cavity  42 , or may be located on different side surfaces of the outflow cavity  42 . 
     When the fluid inlets  43  are located on the same side surface of the inflow cavity  41 , to enable the fluid obtained after the heat exchanging to be more easily discharged from the heat exchange cavity  50 , referring to  FIG.  2    and  FIG.  4   a   , diameters of through holes  21  communicating with the outflow cavities  42  gradually increase in a direction from approaching the fluid inlet  43  to away from the fluid inlet  43 . This is because a quantity of fluids obtained after heat exchanging gradually increases in the heat exchange cavity  50  in the direction from approaching the fluid inlet  43  to away from the fluid inlet  43 , and the diameters of the through holes  21  communicating with the outflow cavities  42  gradually increase, so as to help the fluids obtained after the heat exchanging to be discharged from the heat exchange cavity  50 , and further reduce internal pressure of the heat exchange cavity  50 . 
     Likewise, to further help fluids obtained after heat exchanging to be discharged, referring to  FIG.  3   , a height of a flow guiding pin fin  63  corresponding to the inflow cavity  41  may be greater than a height of a flow guiding pin fin  63  corresponding to the outflow cavity  42 . In this way, this better helps the fluids obtained after the heat exchanging aggregate at a location of a through hole  21  communicating with the outflow cavity  42 , so as to help the fluids obtained after the heat exchanging to be discharged from the heat exchange cavity  50 , and further reduce internal pressure of the heat exchange cavity  50 . 
     For the single-pass heat dissipator, a flow manner of a fluid is as follows: The fluid flows in from the distribution cavity  40  and flows out of the heat exchange cavity  50 . Referring to  FIG.  6    to  FIG.  8   , the distribution cavity  40  is provided with a fluid inlet  43 , and the heat exchange cavity  50  is provided with a fluid outlet  44 . 
     A process in which heat dissipation is performed on the heat emitting apparatus by using the single-pass heat dissipator is as follows: A fluid enters the distribution cavity  40  from the fluid inlet  43 , and flows through the through holes  21  under internal pressure of the distribution cavity  40  and then is jetted into the fluid passage of the heat exchange cavity  50 . The fluid performs heat exchanging with the combination pin fin  62 , the flow guiding pin fin  63 , and the base plate  30 . Under internal pressure of the heat exchange cavity  50 , the fluid obtained after the heat exchanging flows out of the heat exchange cavity  50  from the fluid outlet  44  of the heat exchange cavity  50 . The single-pass heat dissipator has a simple structure, and implements regular flow of a fluid. 
     In the single-pass heat dissipator, there is at least one fluid inlet  43 , and the fluid inlet  43  may be disposed on a side surface of the distribution cavity  40 . For example, it is assumed that the distribution cavity  40  includes a plurality of side surfaces. When there is one fluid inlet  43 , the fluid inlet  43  is located on one side surface of the distribution cavity  40 . However, when there are a plurality of fluid inlets  43 , the plurality of fluid inlets  43  may be located on a same side surface of the distribution cavity  40 , or may be located on different side surfaces of the distribution cavity  40 . 
     Likewise, there is at least one fluid outlet  44 , and the fluid outlet  44  may be disposed on a side surface of the heat exchange cavity  50 . For example, it is assumed that the heat exchange cavity  50  includes a plurality of side surfaces. When there is one fluid outlet  44 , the fluid outlet  44  is located on one side surface of the heat exchange cavity  50 . However, when there are a plurality of fluid outlets  44 , the plurality of fluid outlets  44  may be located on a same side surface of the heat exchange cavity  50 , or may be located on different side surfaces of the heat exchange cavity  50 . 
     When the fluid inlets  43  are located on the same side surface of the distribution cavity  40 , to prevent the fluid obtained after the heat exchanging from overflowing from the through holes  21 , referring to  FIG.  7    and  FIG.  8   , diameters of through holes  21  gradually decrease in a direction from approaching the fluid inlet  43  to away from the fluid inlet  43 . This is because a quantity of fluids obtained after the heat exchanging gradually increases in the heat exchange cavity  50  in the direction from approaching the fluid inlet  43  to away from the fluid inlet  43 , and the diameters of the through holes  21  gradually decrease, so that the fluids obtained after the heat exchanging can be prevented from reversely overflowing to the distribution cavity  40  by using the through holes  21 . A rule that a diameter decreases may be as follows: The diameter may gradually decrease from 0.8 mm to 0.5 mm and then to 0.3 mm, or may gradually decrease from 1.0 mm to 0.8 mm and then to 0.5 mm. The heat dissipator may be designed based on a requirement on internal pressure of the heat exchange cavity  50 . Of course, these examples are not limited herein. 
     To increase entire intensity of the single-pass heat dissipator, referring to  FIG.  7   , a plurality of stiffeners  23  are disposed on the bottom of the distribution cavity  40 . 
     To learn of heat dissipation performance of the heat dissipators, the heat dissipation performance of the heat dissipators is tested, and a test result is as follows: 
     For the distributed heat dissipator using a phase-change heat dissipation manner, the base plate  30 , the combination pin fin  62 , and the flow guiding pin fin  63  are all made of aluminum alloy materials, a fluid is an electronic fluorinated liquid, a quantity of fluids is 0.5 L/min, power of a chip is 300 W, and a contact area between the base plate  30  and the chip is 60 mm×60 mm. Under the foregoing condition, a thermal resistance test is performed on the distributed heat dissipator, and a thermal resistance of the distributed heat dissipator is 0.04° C./W. 
     For the single-pass heat dissipator using a phase-change heat dissipation manner, the base plate  30 , the combination pin fin  62 , and the flow guiding pin fin  63  are all made of brass materials, a fluid is an electronic fluorinated liquid, a quantity of fluids is 0.5 L/min, power of a chip is 300 W, and a contact area between the base plate  30  and the chip is 60 mm×60 mm. Under the foregoing condition, a thermal resistance test is performed on the single-pass heat dissipator, and a thermal resistance of the single-pass heat dissipator is 0.037° C./W. 
     It can be learned from the foregoing tests that, compared with a prior-art jet flow heat dissipator (whose thermal resistance is 0.06° C./W), the thermal resistances of the heat dissipators provided in the embodiments of this application are both less than 0.04° C./W, and heat dissipation performance is improved. 
     According to another aspect, an embodiment of this application provides a communications device. The communications device includes a heat emitting apparatus and the heat dissipator described above, and a base plate of the heat dissipator is in contact with the heat emitting apparatus. The heat dissipator is configured to perform heat dissipation on the heat emitting apparatus. 
     In the heat dissipator in the communications device provided in this embodiment of this application, there is the gap between the flow guiding pin fin and the through hole of the orifice plate, and the combination pin fin is separately in contact with the base plate and the orifice plate. Therefore, when heat dissipation is performed on the heat dissipator, after being jetted into the gap between the flow guiding pin fin and the through hole, a fluid whose temperature is less than a temperature of a heat emitting apparatus enters a fluid passage constituted by the combination pin fin and the flow guiding pin fin, to participate in heat exchanging. In this way, a quantity of fluids that directly flow out of the heat exchange cavity without passing through the fluid passage constituted by the combination pin fin and the flow guiding pin fin is reduced, and fluid utilization is increased. Therefore, the communications device provided in this embodiment of this application can improve heat dissipation efficiency of the communications device. 
     The objectives, technical solutions, and advantageous effects of this application are further described in detail in the foregoing specific implementations. It should be understood that the foregoing descriptions are merely specific implementations of this application, but are not intended to limit the protection scope of this application. Any modification, equivalent replacement, or improvement made based on technical solutions of this application shall fall within the protection scope of this application.