Thermal Management of Circuit Boards

Abstract

The present application relates to thermal management of circuit boards. A semiconductor assembly system includes a motherboard and a cooling system mounted to the motherboard. The cooling system includes sidewalls protruding from the motherboard. A daughterboard extends between the sidewalls and is spaced from the motherboard. The sidewalls and the daughterboard define a cooling channel on the motherboard. A connector is attached to the daughterboard and is configured to receive a semiconductor device daughterboard. The connector has contacts to electrically couple the semiconductor device daughterboard to the daughterboard.

Description

[0001] CROSS REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 043,712, filed on June 24, 2020, the entirety of which is incorporated herein by reference. Technical Field

[0003] The present technology relates to thermal management of semiconductor devices attached to circuit boards. More particularly, some embodiments of the present technology relate to apparatus and techniques for cooling modular components on circuit boards. Background Art

[0004] As manufacturing and design techniques improve, computing components are becoming smaller and more powerful. It is desirable to position components as close together as possible on circuit boards and circuit boards for modular devices to allow for smaller size products and / or provide increased capabilities within the products. Some components, such as power management integrated circuits, generate a lot of heat. Heat can be trapped between the components and the circuit board, which can damage some components or cause system degradation. Therefore, heat can become a limiting factor in component design and system design. Summary of the invention

[0005] According to one aspect of the present technology, a semiconductor component system is provided. The semiconductor component system includes a motherboard, a cooling system, and a connector. The cooling system is mounted to the motherboard and includes sidewalls protruding from the motherboard, a sub-motherboard extending between the sidewalls and spaced apart from the motherboard, wherein the sidewalls and the sub-motherboard define a cooling channel on the motherboard. The connector is attached to the sub-motherboard and is configured to receive a semiconductor device sub-board, wherein the connector has contacts to electrically couple the semiconductor device sub-board to the sub-motherboard.

[0006] According to another aspect of the present technology, a semiconductor component system is provided. The semiconductor component system includes a motherboard, a heat sink, and a connector. The heat sink is configured to physically separate the semiconductor device daughter board from the motherboard through a cooling channel between at least one semiconductor device daughter board and the motherboard. The heat sink includes at least one opening extending from a first end of the cooling channel to a second end of the cooling channel to pass air or cooling fluid between the motherboard and the semiconductor device daughter board. The connector is attached to the heat sink and configured to receive the semiconductor device daughter board, wherein the connector has contacts to electrically couple the semiconductor device daughter board to the heat sink.

[0007] According to another aspect of the present technology, a method for operating a semiconductor assembly system is provided, comprising: transmitting a signal from a daughter board device having a semiconductor device to a mother board separated from the daughter board device through a heat sink having a cooling channel; and driving a cooling medium through the cooling channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Many aspects of the present technology may be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale. Instead, emphasis is placed on illustrating the principles of the present technology.

[0009] Figure 1A is an isometric view of a semiconductor assembly system according to the present technology.

[0010] Figure 1B is an isometric view of another embodiment of a semiconductor assembly system according to the present technology.

[0011] Figure 1C is an isometric view of yet another embodiment of a semiconductor assembly system according to the present technology.

[0012] Figure 2 According to the present technology Figure 1A An end view of a semiconductor assembly system of an embodiment of a cooling system is shown in FIG.

[0013] Figure 3 is a side view of a semiconductor component system enclosed in a housing according to the present technology.

[0014] Figure 4 is an isometric view of a semiconductor assembly system using a closed-loop cooling system in accordance with the present technology. DETAILED DESCRIPTION

[0015] Specific details of several embodiments for cooling circuit boards mounted in close proximity to each other are described below. In one example, a heat sink separates one or more semiconductor device daughter boards from a motherboard. The heat sink may include a daughter board and a vertical wall. The heat sink forms a cooling channel that allows a cooling fluid (e.g., air) to flow between the motherboard and the daughter board. The cooling channel may be open or may have fins therein to provide an increased surface area, which may improve heat transfer when air flows through the cooling channel. The daughter board may be connected to the daughter board using a connector formed of a thermally conductive material to further facilitate heat transfer from the daughter board to the heat sink. In another example, a closed system may circulate a cooling fluid through the cooling channel. Thus, different cooling media (e.g., air or another cooling fluid, such as a liquid) may be moved through the cooling channel to manage the temperature of the circuit board.

[0016] Figure 1A1 is an isometric view of a semiconductor component system 10 having semiconductor device daughter boards 102 (individually identified as daughter boards 102a, 102b, 102c, and 102d), a motherboard 104, and a circuit board cooling system 50 between the daughter boards 102 and the motherboard 104. The circuit board cooling system 50 may have a heat sink 100 that physically separates the daughter boards 102 and the motherboard 104. The heat sink 100, the daughter boards 102a-102d, and the motherboard 104 may be used within a system such as a computer and are thus enclosed within a housing or case (not shown) along with other components. In some embodiments, the daughter board 102 is a memory module that includes one or more of a power management integrated circuit (IC) 138, a logic die 140, a plurality of memory dies 142 (some of which are indicated as 142a and 142b), and / or other dies and ICs. In other embodiments, one or more of the daughter boards 102 may be separate processor modules (e.g., graphics processors) or combined processor / memory modules. In still other embodiments, the semiconductor component system 10 may be operated by transmitting signals from the daughter boards 102 to the mother board 104 when the heat sink 100 separates the daughter boards 102 and the mother board 104 through cooling channels (discussed further below).

[0017] Components mounted on semiconductor device daughterboard 102 generate heat that can degrade system performance and / or damage system components if the heat exceeds a predetermined threshold. In some embodiments, there may be one daughterboard 102 or more than four daughterboards 102a to 102d. In other embodiments, there may be an additional heat sink 100 (not shown) mounted on motherboard 104, with one or more other daughterboards (not shown) mounted on the additional heat sink 100.

[0018] The heat sink 100 includes a daughter board 106, which is attached to side walls 108, 110 so that the daughter board 106 is spaced apart from the motherboard 104. As shown, although the daughter board 106 is substantially parallel to the motherboard 104 and the side walls 108, 110, the daughter board 106 and the side walls 108, 110 can be mounted at other angles relative to the motherboard 104. The side walls 108, 110 are positioned opposite each other and protrude from and are mounted to the motherboard 104. The daughter board 106 can be made of the same material as the motherboard 104, but other materials can be used. In some embodiments, FR4 and copper signal layers can be used for the motherboard 104 and the daughter board 106. The heat sink 100 defines a platform that separates the daughter boards 102a to 102d from the motherboard 104 accordingly.

[0019] More specifically, the cooling channel 112 is formed between the inner surfaces 114a, 114b, 114c and the sidewalls 108, 110 of the motherboard 104 and the daughterboard 106, respectively. The cooling channel 112 has first and second ends 116, 118, through which airflows 132a, 132b enter and leave the cooling channel 112, respectively. Therefore, the cooling channel 112 has at least one elongated flow path extending between the first and second ends 116, 118.

[0020] The heat sink 100 may further include a plurality of fins 124 (although not all are labeled, but individually identified as 124a, 124b, and 124c) extending substantially vertically within the cooling channel 112 and along the length or a portion of the length of the cooling channel 112. Figure 1A One expected advantage of the embodiment shown in FIG. 1 is that the fins 124 provide more surface area for dissipating heat within the cooling channel 112. The heat sink 100 may also have a conductive plate 136 between the top ends of the fins 124 and the inner surface 114a of the daughter board 106 to assist in heat transfer from the semiconductor device daughter board 102 to the fins 124. In another embodiment, the fins 124 may be attached to at least one of the inner surface 114a of the daughter board 106 and the mother board 104. The sub-channels 126 (although not all labeled, but individually identified as 126a, 126b, and 126c) are formed between the sidewall 110 and the fins 124a, between the fins 124a and the fins 124b, between the fins 124b and the fins 124c, etc. The fins 124 and the conductive plate 136 may be made substantially of metal, such as copper, aluminum, aluminum alloys, or any other suitable material.

[0021] As discussed further below, a fan (e.g. Figure 3 1 (shown in the embodiment of FIG. 1 ) to drive airflow (arrows 132a and 132b) (e.g., cooling medium) through the cooling channels 112. Depending on the position of the fan, air can be pushed or pulled through the cooling channels 112. In operation, some of the heat generated by the daughter board 102 is transferred to the heat sink 100. The airflow 132a, 132b passing through the cooling channels 112 cools the fins 124 (i.e., draws heat away from the fins 124) to manage the temperature of the daughter board 102.

[0022] The size of the heat sink 100 may be based on the cooling requirements of the system and the available space. For example, the height 134 of the cooling channel 112 may be determined based on the heat generated by the daughterboard 102, the volume and velocity of air generated by the fan(s), the expected ambient air temperature or cooling air temperature, the length of time the system will be operated, or other factors that affect the amount of heat that the system may generate.

[0023] Providing cooling channels 112 between daughterboard 102 and motherboard 104 can remove heat from the bottom edge of daughterboard 102 in addition to removing heat directly from the components via airflow between daughterboards 102. Therefore, cooling system 50 is expected to reduce the operating temperature of the components compared to systems that only remove heat from above and between daughterboards 120.

[0024] When the semiconductor device sub-boards 102 are memory modules, the distance or pitch between the sub-boards 102 may be smaller, such as approximately 7.6 millimeters (mm). Each of the sub-boards 102 may have high power (e.g., approximately 15 watts) and generate a large amount of heat. Even when fans are used to provide cooling between and on the sub-boards 102, the temperature may rise to unacceptable levels and may cause component failure and performance degradation.

[0025] The semiconductor assembly system 10 may further include connectors 120 (individually identified as 120a, 120b, 120c, and 120d) mounted to an outer surface 122 of the daughter board 106 to receive the daughter boards 102a to 102d and mechanically and electrically connect the daughter boards 102a to 102d to the heat sink 100. The connectors 120a to 102d may include a thermally conductive dielectric material such as a thermally conductive plastic or other high-K dielectric material, FR4 or other plastic material, and electrical contacts. Thus, the connectors 120a to 120d may thermally conduct heat from the daughter boards 102a to 102d to the heat sink 100.

[0026] The cooling system 50 may include traces 128 (some traces are individually identified as 128a, 128b, 128c, and 128d) formed along the outer surfaces 130 of the sidewalls 108, 110 and along the motherboard 106 to electrically couple the contacts of the connector 120 to the motherboard 104. In some embodiments, the traces 128 may be formed along the inner surfaces 114b, 114c of the sidewalls 108, 110. In still further embodiments, the traces 128 (individually identified as 128e, 128f, 128g, and 128h) may be formed along the outer surfaces of the motherboard 106 and the sidewalls 108, 110 and / or within a layer of material of the motherboard 106 and the sidewalls 108, 110 and / or embedded in the material of the motherboard 106 and the sidewalls 108, 110.

[0027] Figure 1B is an isometric view of a semiconductor assembly system 10 having another circuit board cooling system 150 according to the present technology. Figure 1A , 1B Similar reference numerals in 1C refer to similar components, but in Figure 1B and 1C Not all components are indicated.

[0028] The cooling passages 112 of the system 150 are open and do not include Figure 1A Thus, airflow 132 passes through cooling channel 112, for example, through an opening extending from first end 116 of cooling channel 112 to second end 118 of cooling channel 112, as shown in FIG. Figure 1A The airflow 132 in the cooling channel 112 dissipates some of the heat from the heat sink 100 to manage the temperature of the components on the daughterboard 102 .

[0029] As Figure 1A , illustrating traces 128a-128h. Additionally, traces 128i and 128j are shown on the inner surface 114b of the heat sink 100. Thus, in some embodiments, some or all of the traces 128a-128j may electrically couple the contacts of the connector 120 to the motherboard 104.

[0030] Figure 1C A semiconductor assembly system 10 with another embodiment of a circuit board cooling system 170 according to the present technology is shown. In this embodiment, the sidewalls 108 and 110 have one or more openings 180 (shown as 180a, 180b, and 180c in the sidewall 110). More or fewer openings 180 may be used and their placement along the sidewalls 108 and 110 is not limited to the locations shown. Thus, ambient air outside the heat sink 100 may enter through the openings 180 to mix with the air passing through the cooling channels 112 and / or air within the cooling channels 112 may exit the heat sink 100 through the openings 180. The size of the openings 180 may be determined by the system cooling requirements. In some embodiments, some of the sidewalls 108, 110 may have one or more openings 180, while other sidewalls may be solid. Figure 1C The fin 124 is shown in FIG. 1 , but in another embodiment, Figure 1C The cooling passage 112 may be open without fins, such as Figure 1B As shown in .

[0031] Figure 2 According to the present technology, a cooling system 50 ( Figure 1A ) is an end view of a semiconductor assembly system 10 of an embodiment of the present invention. Figure 1A In addition to Figure 1A In addition to or instead of the trace 128 shown in Figure 1A128 shown in the figure, the traces connecting the daughterboard 102 and the motherboard 104 may also extend through the cooling channel 112. For example, the trace circuit boards 202 (individually identified as 202a, 202b, 202c, and 202d) may be positioned in the cooling channel 112 in place of some of the fins 124. In some embodiments, the trace circuit board 202 may have trace lines that are integral to (e.g., formed on and / or within) a substrate made of FR4, although other materials may be used. As shown, each of the daughterboards 102 may have a corresponding trace circuit board 202. In another embodiment, one of the trace circuit boards 202 may transmit signals for more than one daughterboard 102.

[0032] In some embodiments, the cooling system 50 may have fins 124 interspersed with trace circuit boards 202 in the cooling channel 112. Thus, sub-channels may be formed between adjacent items within the cooling channel 112. For example, the sub-channel 204a is formed between the sidewall 110 and the fin 124a, the sub-channel 204b is formed between the fin 124a and the trace circuit board 202a, and the sub-channel 204c is formed between the trace circuit board 202a and the fin 124b.

[0033] In operation, as cooling air moves through cooling channel 112 to the other end, the air passes through sub-channel 204 along fins 124 and trace circuit board 202. The air within cooling channel 112 draws heat away from fins 124 and trace circuit board 202 to manage the temperature of components on daughterboard 102.

[0034] In another embodiment, only the trace circuit board 202 may be mounted within the cooling channel 112. In this configuration, there are no other cooling fins within the cooling channel 112. Thus, sub-channels are formed between one of the sidewalls and adjacent trace circuit boards 202 and between adjacent trace circuit boards 202. Likewise, air passing through the sub-channels in the cooling channel 112 will draw heat away from the trace circuit board 202 to manage the temperature of the components on the daughter board 102.

[0035] Figure 3 A side view of a semiconductor assembly system 10 enclosed within a housing 300 according to the present technology is shown. The sidewall 110 of the heat sink 100 is indicated with dots. In many cases, multiple circuit board cooling systems 50 can be enclosed within the housing 300. For example, multiple heat sinks 100 can be mounted on a motherboard 104, and each heat sink 100 can connect one or more daughter boards 102 to the motherboard 104.

[0036] The fan 302 may be mounted inside the housing 300 or outside the housing 300, as shown. The fan 302 blows ambient air 304 into the housing 300 through an air inlet 306. A portion of the airflow passes along the daughterboard 102 (arrow 308), while another portion of the airflow passes through the cooling channel 112 (arrow 310). The upper portion of the airflow (arrow 308) passes between adjacent daughterboards 102 and between adjacent heat sinks 100. The housing 300 has one or more air outlets 312 (indicated as 312a, 312b, and 312c) or vents through which heated air leaves the housing 300. One expected advantage of the embodiment shown in FIGS. 1 to 3 is that by providing an open channel 112 between the motherboard 104 and the daughterboard 102, the airflow passes under the daughterboard 102 to further remove heat from the components. This may reduce the temperature of all components within the housing.

[0037] Figure 4 FIG. 1 is an isometric view of a semiconductor assembly system 10 using a closed-loop cooling system 400 and a circuit board cooling system 50 according to the present technology. Figure 1A Like reference numerals refer to like components in the Figure 4 Not all components are shown. The heat sink 100 includes a motherboard 106 and sidewalls 108 and 110 forming a cooling channel 112. The heat sink 100 may have a cooling channel 112 having a Figure 1A The fins 124 shown in FIG. 1 and the cooling channels 112 may not be as Figure 1B The traces 128a to 128h or other traces (not shown) on or within the material of the heat sink 100 may provide electrical connection and communication between the daughter board 102 and the mother board 104.

[0038] The cooling system 400 may be a closed system that drives a cooling fluid through the heat sink 100. The cooling system 400 may have a cooling module 404 and a fluid containment system 402a, 402b, such as a pipe, hose, or other enclosed system component, that transfers the cooling fluid from the fluid cooling module 404 and through the cooling channel 112. The fluid containment system 402 prevents the cooling fluid from contacting the heat sink 100 and the motherboard 104.

[0039] The temperature of the cooling fluid entering the cooling channel 112 may be lower than the temperature within the cooling channel 112. The temperature of the cooling fluid increases as the cooling fluid moves through the cooling channel 112. In some embodiments, the fluid cooling system 400 may be a two-phase system such that when the cooling fluid leaves the cooling channel 112, the temperature of the cooling fluid has increased to its evaporation point and when it re-enters the first end 116, it has condensed back to a liquid state.

[0040] The fluid cooling module 404 may be mounted on or near the motherboard 104 or may be external to the motherboard 104. The fluid cooling module 404 may include a pump mechanism 406 to circulate the cooling fluid through the fluid containment system 402 and a cooling mechanism 408 that cools the cooling fluid to a lower or predetermined temperature before recirculating the cooling fluid through the fluid containment system 402. In some embodiments, the fluid cooling module 404 may also have a reservoir 410 to hold the cooling fluid until it is at a desired temperature or to mix the returned cooling fluid with the lower temperature cooling fluid.

[0041] Although only one heat sink 100 is shown connected to the fluid cooling module 404, in other embodiments, the fluid cooling module 404 may be configured to provide cooling fluid to multiple heat sinks 100 simultaneously. For example, multiple heat sinks 100 may be aligned on the motherboard 104 so that their respective cooling channels 112 are aligned. A single fluid containment system 402 may route cooling fluid through more than one cooling channel 112 before returning the cooling fluid to the fluid cooling module 404. In other configurations, the fluid containment system 402 may have a manifold that divides the fluid flow into multiple branches that are fluidly connected to route cooling fluid through multiple cooling channels 112 of multiple heat sinks 100.

[0042] The present disclosure is not intended to be exhaustive or to limit the present technology to the precise form disclosed herein. Although specific embodiments are disclosed herein for illustrative purposes, various equivalent modifications are possible without departing from the present technology, as will be recognized by those skilled in the relevant art. In some cases, numerous well-known structures and functions are not shown or described in detail to avoid unnecessarily obscuring the description of the embodiments of the present technology. Although the steps of the method can be presented in a specific order herein, alternative embodiments can perform the steps in different orders. Similarly, certain aspects of the present technology disclosed in the context of a specific embodiment can be combined or eliminated in other embodiments. In addition, although the advantages associated with certain embodiments of the present technology may have been disclosed in the context of those embodiments, other embodiments may also exhibit such advantages, and not all embodiments necessarily exhibit such advantages or other advantages disclosed herein to fall within the scope of the present technology. Therefore, the present disclosure and associated technology may encompass other embodiments that are not explicitly shown or described herein.

[0043] Throughout this disclosure, the singular terms "one", "an" and "the" include plural reference objects unless the context clearly indicates otherwise. Similarly, unless the word "or" is clearly limited to only represent a single item that is mutually exclusive with other items about a list of two or more items, the use of "or" in this list should be interpreted as including any single item in (a) the list, (b) all items in the list, or (c) any combination of items in the list. In addition, the term "comprising" is used throughout to represent at least including (several) listed features, so that any more number of the same features and / or other features of additional types are not excluded. References to "one embodiment", "some embodiments" or similar expressions herein represent that the specific features, structures, operations or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present technology. Therefore, the appearance of such phrases or expressions herein does not necessarily all refer to the same embodiment. In addition, various specific features, structures, operations or characteristics can be combined in any suitable manner in one or more embodiments.

[0044] From the foregoing, it will be apparent that specific embodiments of the technology have been described herein for purposes of illustration, but that various modifications may be made without departing from the scope of the invention.The technology is not limited, except as by the appended claims.

Claims

1. A semiconductor component system, comprising: motherboard; a cooling system mounted to the motherboard, the cooling system comprising sidewalls protruding from the motherboard, a daughter board extending between the sidewalls and spaced apart from the motherboard, wherein the sidewalls and the daughter board define a cooling channel on the motherboard, the cooling channel comprising at least one opening extending from a first end of the cooling channel to a second end of the cooling channel for conveying air or cooling fluid between the motherboard and the daughter board; a second cooling system mounted to the motherboard, the second cooling system comprising second sidewalls protruding from the motherboard, a second daughter board extending between the second sidewalls and spaced apart from the motherboard, wherein the second sidewalls and the second daughter board define a second cooling channel on the motherboard, the second cooling channel comprising at least one opening extending from a first end of the second cooling channel to a second end of the second cooling channel for conveying the air or cooling fluid between the motherboard and the second daughter board; and A connector is attached to the daughter board and is configured to receive a semiconductor device daughter board, wherein the connector has contacts to electrically couple the semiconductor device daughter board to the daughter board.

2. The system according to claim 1, further comprising: at least one fin within the cooling channel extending along at least a portion of the length of the cooling channel to form at least two sub-channels; and Traces extend along the daughter board and the sidewalls to electrically couple the connector to the motherboard.

3. The system of claim 2, wherein the traces are formed along the sidewalls and an outer surface of the motherboard.

4. The system of claim 2, wherein the traces are formed along the sidewalls and an inner surface of the daughter board.

5. The system of claim 2, wherein the traces are formed within the sidewalls and layers of the motherboard.

6. The system of claim 2, further comprising at least one trace circuit board extending through the cooling channel between the daughter board and the mother board, the traces being integrally formed with the trace circuit board.

7. The system of claim 1, further comprising a fluid containment system extending through the cooling channel to move a cooling fluid through the cooling channel.

8. The system of claim 1, wherein the connector comprises a thermally conductive dielectric.

9. A semiconductor component system, comprising: motherboard; a heat sink configured to physically separate the semiconductor device daughter board from the motherboard through at least one cooling channel between the semiconductor device daughter board and the motherboard, the heat sink including at least one opening extending from a first end of the cooling channel to a second end of the cooling channel to pass air or cooling fluid between the motherboard and the semiconductor device daughter board; a connector attached to the heat sink and configured to receive the semiconductor device daughter board, wherein the connector has contacts to electrically couple the semiconductor device daughter board to the heat sink; and a second heat sink configured to physically separate the second semiconductor device daughter board from the motherboard through at least a second cooling channel between the second semiconductor device daughter board and the motherboard, the second heat sink comprising at least one opening extending from a first end of the second cooling channel to a second end of the second cooling channel to pass the air or cooling fluid between the motherboard and the second semiconductor device daughter board, wherein the heat sink further comprises: two side walls attached to the motherboard; a daughter board extending between the two side walls and to which the connector is mounted; and A trace electrically couples the connector and the motherboard, the trace extending along at least one of the outer surface, the inner surface, and within the layers of the two sidewalls and the motherboard.

10. The system of claim 9, further comprising a plurality of fins extending vertically within the cooling channel, the plurality of fins further extending along at least a portion of the cooling channel between the first end and the second end.

11. The system of claim 10, further comprising a conductive plate in the cooling channel between the plurality of fins and the heat sink, the conductive plate and the plurality of fins being formed of metal.

12. The system of claim 9, further comprising at least one trace circuit board extending through the cooling channel to electrically couple the contacts of the connector to the motherboard.

13. The system of claim 9, further comprising: a second connector attached to the heat sink and configured to receive a second semiconductor device daughterboard, wherein the second connector has second contacts to electrically couple the second semiconductor device daughterboard to the heat sink; and A second trace electrically couples the second connector and the motherboard, the second trace extending along at least one of the outer surface and the inner surface of the sidewall and the motherboard and within the layer of the sidewall and the motherboard, the trace and the second trace being formed separately from each other.

14. The system of claim 9, wherein the connector comprises a thermally conductive dielectric.

15. The system of claim 9, further comprising a fluid containment system to drive a cooling fluid through the cooling channel.

16. A method for operating a semiconductor assembly system as claimed in claim 9, the method comprising: transmitting a signal from the semiconductor device daughter board to the motherboard separate from the semiconductor device daughter board through the heat sink having the cooling channel; and A cooling medium is driven through the cooling passage.

17. The method of claim 16, wherein said driving said cooling medium further comprises flowing air through said cooling passage.

18. The method of claim 16, wherein said driving said cooling medium further comprises pumping a cooling fluid through said cooling passage.

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