Abstract:
The present disclosure further contemplates a system and method that cools metal core printed circuit boards by circulating a liquid coolant so that it contacts the base metal of the metal core printed circuit board. In one example the present disclosure contemplates a direct liquid cooled MCPCB system that may include a liquid cavity creating component coupled to the base plate of a MCPCB allowing a liquid coolant to come into contact with the base plate of the MCPCB for cooling of the MCPCB. The direct liquid cooled MCPCB system may minimize thermal bottlenecks between the electrical components and the cooling fluid while reducing the number of components required in previous liquid cooled electronics systems.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority under 35 U.S.C. §119 based on U.S. Provisional Application No. 62/050,488, filed on Sep. 15, 2014 and U.S. Provisional Application No. 62/051,383, filed on Sep. 17, 2014. The disclosure of both U.S. Provisional Application No. 62/050,488 and U.S. Provisional Application No. 62/051,383 are incorporated herein by reference. 
     
    
     FIELD OF INVENTION 
       [0002]    The present disclosure contemplates a system and apparatus that cools metal core printed circuit boards. The present disclosure further contemplates a system and method that cools metal core printed circuit boards by circulating a liquid coolant so that it contacts the base metal of the metal core printed circuit board. 
       BACKGROUND 
       [0003]    There have been a number of advancements in the field of thermal management for electronic circuit boards. One innovation has been the Metal Core Printed Circuit Board (“MCPCB”). This approach utilizes a layer of thermal conductive metal, such as copper or aluminum, as the base plate for the circuit board construction. The circuits and components are electrically isolated from the base plate by a thin dielectric layer. The close proximity of the base plate to the electronic circuits and electronic components allows the heat to be dissipated from the source more effectively. 
         [0004]    Improvement to the MCPCB approach has included using raised areas on the base plate to protrude through the dielectric layer, providing more thermal attachment options with electronic components, such as soldering or welding. Additional improvements include utilizing thermal transfer vias, made of metals such as copper or aluminum, that allow the transfer of heat through multiple circuit board layers on a single MCPCB. 
         [0005]    MCPCBs require effective thermal management systems for the removal of heat from the base plate. Current liquid cooling systems are designed as self-contained cold plates or heat pipes that are attached to circuit boards or electronic components with methods such as soldering, thermal pastes, thermal adhesives, and mechanical systems. Unfortunately, these conventional systems introduce additional material layers between the thermal transfer fluid and circuit board, which can increase thermal resistance and act as a thermal bottleneck. 
       SUMMARY OF INVENTION 
       [0006]    In one example the present disclosure contemplates a direct liquid cooled MCPCB system that may include a liquid cavity creating component coupled to the base plate of a MCPCB. The direct liquid cooled MCPCB system may cool a MCPCB by coupled to one or more liquid cavity creating components to at least one surface of the MCPCB base plate, allowing a liquid coolant to come into contact with the base plate of the MCPCB for cooling of the MCPCB. The direct liquid cooled MCPCB system may minimize thermal bottlenecks between the electrical components and the cooling fluid while reducing the number of components required in previous liquid cooled electronics systems. This may result in increased thermal dissipation rates, higher possible input temperatures for cooling fluids, lower energy consumption, simplified production methods, and lower production costs. 
         [0007]    In some examples, the present disclosure contemplates a direct liquid cooled MCPCB system that may include a liquid cavity creating component and a fastening mechanism(s). The liquid cavity creating component may serve as a heat pipe allowing liquid coolant to flow in a self-contained system or the liquid cavity creating component may have ports to allow liquid coolant to flow into and out of the direct liquid cooled MCPCB system. In the direct liquid cooled MCPCB system, the liquid cavity creating component may be coupled to the MCPCB using the fastening mechanisms. In some example direct liquid cooled MCPCB systems, the liquid cavity creating component may be coupled to a MCPCB cover and the MCPCB cover may be coupled to the MCPCB using another fastening mechanism. In another example the liquid cavity creating component, the MCPCB cover, and the MCPCB may all be coupled together using only the first fastening mechanism. In some examples where ports are utilized in the direct liquid cooled MCPCB system, the liquid cavity creating component may have a multiple liquid ports, where a liquid coolant may flow into the liquid cavity creating component through one liquid port and the liquid coolant may flow out of the liquid cavity creating component through another liquid port. In some examples, the liquid cavity creating component may have an integrated external thermal interface for removing excess heat from the base plate of the MCPCB, while also absorbing or radiating heat from or to the area surrounding the system. 
         [0008]    In another example the present disclosure contemplates a method for direct cooling of a MCPCB including coupling a liquid cavity creating component to a MCPCB and circulating a liquid coolant through a cavity between the liquid cavity creating component and the base plate of the MCPCB, such that the liquid coolant comes into direct contact with the base plate of the MCPCB. Example methods for direct cooling of a MCPCB may use a self-contained heat pipe to directly cool the base plate of the MCPCB or the method for direct cooling of a MCPCB may use port(s) to circulate the liquid coolant in the cavity between the liquid cavity creating component and the base plate of the MCPCB. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The foregoing and other features of the present disclosure will become more fully apparent from the following description, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only several examples in accordance with the disclosure and are therefore, not to be considered limiting of its scope, the disclosure will be described with additional specificity and detail through use of the accompanying drawings. 
           [0010]    In the drawings: 
           [0011]      FIG. 1  depicts an exploded view of an example direct liquid cooled MCPCB system. 
           [0012]      FIG. 2  depicts a cross-sectional side view of an example direct liquid cooled MCPCB system. 
           [0013]      FIG. 3  depicts a cross-sectional side view of an example direct liquid cooled MCPCB system with an extended external thermal interface. 
           [0014]      FIG. 4  depicts a side perspective view of an example liquid cavity creating component for the direct liquid cooled MCPCB system. 
           [0015]      FIG. 5  depicts an example method for direct cooling of a MCPCB. 
       
    
    
     DETAILED DESCRIPTION 
       [0016]    In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative examples described herein are not meant to be limiting. Other examples may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the Figures, may be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure. 
         [0017]    Turning to the figures in detail,  FIG. 1  and  FIG. 2  depict an example direct liquid cooled MCPCB system  100 . The direct liquid cooled MCPCB system  100  may be comprised of a liquid cavity creating component  111 , a MCPCB cover  112 , a fastening mechanism(s)  113 , a liquid port  115 , a liquid port  116 , and a MCPCB  120 . The MCPCB  120  in the example direct liquid cooled MCPCB system  100  may include a circuit board combined with a base plate  121 . In the direct liquid cooled MCPCB system  100 , the liquid cavity creating component  111  may be coupled to the MCPCB cover  112  and the MCPCB  120  using a fastening mechanism  113 . In some examples, while the liquid cavity creating component  111  is coupled to the MCPCB cover  112  using the fastening mechanism  113 , the MCPCB cover  112  may have a second fastening mechanism for attachment to a MCPCB  120 . The liquid cavity creating component  111  may have an external fastening mechanism  1119  on the exterior surface of the liquid cavity creating component  1112 . The external fastening mechanism  1119  may attach the direct liquid cooled MCPCB system  100  to surrounding structures, for example shelving for indoor farming or server farms. 
         [0018]    In the direct liquid cooled MCPCB system  100 , the liquid cavity creating component  111  may have liquid ports  115 ,  116 . The liquid coolant may flow into the liquid cavity creating component  111  through one liquid port  115  and the liquid coolant may flow out of the liquid cavity creating component  111  through another liquid port  116 . When using liquid ports  115 ,  116  in the liquid cavity creating component  111 , the direct liquid cooled MCPCB system  100  may remove heat generated by a MCPCB  120  by one or more surfaces of the base plate  121  as a direct contact area for liquid coolant. The containment of liquid coolant may be managed by one or more liquid cavity creating component  111  that interface with the base plate  121  of the MCPCB  120  where the interior surface of the liquid cavity creating component  1111  forms sealed cavity with base plate  121  of the MCPCB  120 . The sealed cavity may be formed using a gasket  117 , where the gasket may be coupled to the base plate  121  of the MCPCB  120  and also coupled to the liquid cavity creating component  111 . The liquid cavity creating component  111  may form a self-contained system, such as a heat pipe, or may be designed with one or more liquid ports, for example the liquid port  115  and the liquid port  116  shown in  FIG. 1 , to allow for the inlet and outlet of liquid coolant or gas coolant in an open or closed loop system. 
         [0019]    In some examples, the direct liquid cooled MCPCB system may use a self-contained heat pipe design where the liquid coolant circulates through the liquid cavity between the liquid cavity creating component  111  and the base plate  121  of the MCPCB  120  using known methods such as, but not limited to, gravity, capillary pressure, or a mechanical agitator. In the example direct liquid cooled MCPCB system with the self-contained heat pipe design there are no inlet or outlet ports in the liquid cavity creating component  111 . 
         [0020]    The liquid cavity creating component  111  may be made of any thermally conductive material, such as aluminum or copper. The liquid cavity creating component  111  and the MCPCB cover  112  may be manufactured using many methods including but not limited to extrusion, machining, photochemical etching, molding, three-dimensional printing, and laser etching. The fastening mechanism  113  and other fastening mechanisms may vary among many methods, including but not limited to adhesives, soldering, ultrasonic welding, laser welding, and mechanical systems as depicted in  FIGS. 1-3 . The direct liquid cooled MCPCB system  100  may use any type of liquid coolant, including but not limited to water, deionized water, glycols, Betaine, Halomethanes, and/or dielectric fluid. The direct liquid cooled MCPCB system  100  may use gas coolants in conjunction with the liquid coolant. The interior surface of the liquid cavity creating component  1111 , the exterior surface of the liquid cavity creating component  1112 , the base plate of the MCPCB  121 , the interior surface of the MCPCB cover  1121 , and the exterior surface of the MCPCB cover  1122  may have any number of features that benefit performance, functionality, or manufacturing. These features include but are not limited to textured surfaces, channels, protrusions, fins, thermal coatings, corrosion resistant coatings, tubing, tubing connectors, tubing locks, gaskets, and electrical connections. 
         [0021]    The ports in the liquid cavity creating component  111 , such as liquid ports  115 ,  116  shown in  FIG. 1  and  FIG. 4 , may interface with hose attachments  1150 ,  1160  as shown in  FIGS. 1 and 4 . The interface between the liquid ports  115 ,  116  in the liquid cavity creating component  111  and the hose attachments  1150 ,  1160  may be sealed using known methods, such as, but not limited to an O-ring. The hose attachments  1150 ,  1160  depicted and any other hose attachments may interface with the liquid cavity creating component using any know attachment method, such as, but not limited to, adhesives, soldering, ultrasonic welding, laser welding, and mechanical systems. 
         [0022]    The direct liquid cooled MCPCB system  100  may also integrate an external thermal interface  118  with the liquid cavity creating component  111  as shown in  FIG. 3 . The external thermal interface  118  may include features on the exterior surface of the liquid cavity creating component  1112  that increase the exterior surface area of the liquid cavity creating component  111 , improving thermal transfer rates with the surrounding area. These features include but are not limited to surface textures, holes, fins, rods, and wings. The external thermal interface  118  may be a feature of the same piece the liquid cavity creating component  111  is made from as shown in  FIG. 3 . However, in some examples, the external thermal interface  118  may be a component that is attached to the liquid cavity creating component  111  by methods including but not limited to adhesives, soldering, three-dimensional printing, ultrasonic welding, laser welding, and mechanical systems. Example methods to produce the external thermal interface  118  include but are not limited to extrusion, machining, laser cutting, liquid cutting, molding, and stamping. The external thermal interface  118  may be made of high thermal conducting solids, such as aluminum, copper, or ceramic. 
         [0023]    Depending on the external surface temperature of the system, the external thermal interface  118  may cause the temperature of the surrounding area to increase or decrease. If the external surface temperature of the direct liquid cooled MCPCB system  100  is below the surrounding area temperature, for example, the external thermal interface  118  will absorb heat from the surrounding area. If the external surface temperature of the direct liquid cooled MCPCB system  100  is above the surrounding area temperature, the external thermal interface  118  will radiate heat to the surrounding area. The rate of thermal transfer may be increased by utilizing a larger number of external thermal interface  118 , a larger sized external thermal interface  118 , or both, in order it increase surface area. The rate of thermal transfer may also be increased through the use of one or more fluid movers, such as but not limited to fans, pumps, sprayers, and propellers. 
         [0024]    As shown in  FIG. 3  the liquid cavity creating component  111  of the direct liquid cooled MCPCB system  100  may lack a MCPCB cover  112  and the liquid cavity creating component  111  may be coupled directly to the MCPCB  120  using a MCPCB fastening means  119 . The base plate  121  of the MCPCB  120  and the interior surface of liquid cavity creating component  1111  form the liquid cavity for the liquid coolant. The liquid coolant may flow in and out of the liquid cavity creating component  111  through liquid ports  115 ,  116 . A gasket or other known sealing means may be used to seal the cavity formed between the base plate  121  of the MCPCB  120  and the interior surface of liquid cavity creating component  1111 . 
         [0025]    As shown in  FIG. 3 , many kinds of MCPCB  120  may be used in the direct liquid cooled MCPCB system  100  and the MCPCB  120  may have many configurations.  FIG. 3  depicts a MCPCB that includes a light emitting diode (LED)  123 , LED housing  122 , a LED heat sink  124 , an LED bond wire  125 , and a dielectric layer  126 . 
         [0026]    The internal temperature of the direct liquid cooled MCPCB system  100  may be controlled through means including but not limited to liquid coolant flow rate, input liquid coolant temperature, type of liquid coolant in the system, and power consumption of the electronic components. The temperatures within the direct liquid cooled MCPCB system  100  and the surrounding area may be monitored and controlled through a number of devices, including but not limited to thermostats, thermometers, gauges, flow controllers, electronic processors, and heat exchangers. The temperature monitoring and controlling devices may be included as devices within or attached to the direct liquid cooled MCPCB system  100 , or independently located. In addition to the benefit of dual temperature control for electronic devices and their surrounding areas, some examples may reduce the number of total components needed to accomplish both tasks, simplifies the manufacturing process, reduces thermal bottlenecks, lowers the total cost of production, and reduces energy consumption. 
         [0027]      FIG. 5  depicts an example method for direct cooling of a MCPCB  200 . The method for direct cooling of a MCPCB  200  may include coupling a liquid cavity creating component to a MCPCB  201  and circulating a liquid coolant through a cavity between the liquid cavity creating component and the base plate of the MCPCB  202 . The method for direct cooling of a MCPCB allows the liquid coolant to come into contact with the base plate of the MCPCB  202 . The method for direct cooling of a MCPCB  200  may use a self-contained heat pipe to directly cool the base plate  121  of the MCPCB  120  or the method for direct cooling of a MCPCB  200  may use a ports to circulate the liquid coolant in the cavity between the liquid cavity creating component  111  and the base plate  121  of the MCPCB  120 . 
         [0028]    While various aspects and examples have been disclosed herein, other aspects and examples will be apparent to those skilled in the art. The various aspects and examples disclosed herein are for purposes of illustration and are not intended to be limiting. 
         [0029]    What is claimed is: