Patent ID: 12193201

DETAILED DESCRIPTION

The example embodiments disclosed herein are illustrative of cooling assemblies, and systems of the present disclosure and methods/techniques thereof. It should be understood, however, that the disclosed embodiments are merely examples of the present disclosure, which may be embodied in various forms. Therefore, details disclosed herein with reference to example cooling systems and associated processes/techniques of fabrication/assembly and use are not to be interpreted as limiting, but merely as the basis for teaching one skilled in the art how to make and use the assemblies/systems and/or alternative assemblies/systems of the present disclosure.

The present disclosure provides for cooling systems, assemblies and methods (e.g., for semiconductor devices; for refrigerant cooling; for cryogenic cooling). More particularly, the present disclosure provides for mini-channel cold plate cooling assemblies, systems and methods for semiconductor devices (e.g., wide-bandgap (WBG) power semiconductor devices), with the cooling assemblies, systems and methods utilizing three-dimensional adaptive flow-paths using bi-metal fins.

As noted above, current practice provides that some conventional system-level thermal designs have become increasingly difficult, because smaller wide-bandgap (WBG) semiconductor device sizes typically result in worse thermal performance. As such, power converter designs can be affected by such disadvantages. As noted, the uniform thermal distribution between devices can be important for the system life cycle and reliability. Typically, the multi-level topology can be a good candidate in order to get an improved performance. This topology can have a complicated configuration, as more WBG devices can be required compared to some conventional two-level (2L) systems. In addition, some multi-level topologies can have an unbalanced current/voltage state. This can cause an unbalanced thermal state on the heatsink or coldplate. Thus, an improved WBG device arrangement and cooling path can be a high priority factor for overall performance.

As such, some conventional multi-pass coldplates have caused severe unbalanced thermal status due to an increased temperature. Some conventional mini-channel coldplates have also caused unbalanced thermal status due to the multi-level topology. As noted, a flow control system can be required in accordance with an unbalanced thermal status. In order to get improved performance and a long life cycle, the present disclosure provides for coldplate assemblies based on adaptive flow control systems and methods.

The present disclosure provides for mini-channel cold plate cooling assemblies, systems and methods that may improve cooling performance and/or enable local cooling control. One benefit of the cooling assemblies and systems of the present disclosure can be achieved by adapting the internal coolant flow-path in three-dimensions (3D) according to the surface temperature. The present disclosure provides for bi-metal fins or strips that operate as both the surface-temperature sensors and actuators without input energy. The bi-metal strips guide the coolant flow to a low-drag channel when the surface temperature is low, and guide the coolant flow to the near-surface channel when the surface temperature is high.

FIG.1is a partial top side perspective view of a cooling assembly10, according to certain embodiments of the present disclosure. In example embodiments, cooling assembly10takes the form of a mini-channel cold plate cooling assembly10for semiconductor devices12(seeFIG.3) (e.g., wide-bandgap (WBG) power semiconductor devices12), with the cooling assembly10utilizing three-dimensional adaptive flow-paths using bi-metal fins14.FIG.2is a cross-sectional side view of the cooling assembly10ofFIG.1.

As shown inFIG.1, cooling assembly10includes cold plate side walls16A-16D, a cold plate top wall18, and a cold plate bottom wall20. In example embodiments, walls16A-16D,18and20are fabricated from aluminum (e.g., aluminum cold plate walls16A-16D,18and20).

The semiconductor devices12of assembly10can be positioned on a substrate22(e.g., printed circuit board (PCB)22or ceramic plate22). In example embodiments, each semiconductor device12is a wide band gap device12(e.g., GaN device12, SiC MOSFET (metal-oxide-semiconductor field-effect transistor) device12, etc.). The substrate22can be positioned on the cold plate top wall18of assembly10.

Side wall16A can include a coolant inlet24, and side wall16D can include a coolant outlet26.

In example embodiments and as shown inFIG.2, a plurality of bi-metal fins14can extend from the top wall18, and a plurality of wall extensions28can extend from bottom wall20. In general, each bi-metal fin14includes a first metal material38and a second metal material40. The first metal material38can be different than the second metal material40.

The plurality of wall extensions28can extend from bottom wall to define a plurality of lower channels30for a coolant31(e.g., fluid or liquid coolant31) introduced to inlet24of assembly10.

Each bi-metal fin14of the plurality of bi-metal fins14can be L-shaped or C-shaped, and can extend from the top wall18to define a plurality of adjustable upper channels32for coolant31. In general, the L-shaped or C-shaped bi-metals fins14include a side wall portion34and a bottom wall portion36.

The bi-metal fins14provide thermal uniformity of assembly10. More particularly, the bi-metal fins14provide for adaptive flow of coolant31through assembly10.

One benefit of cooling assembly10can be achieved by adapting the internal coolant31flow-path in three-dimensions (3D) according to the surface temperature of top wall18(e.g., via heat from devices12). The bi-metal fins or strips14operate as both the surface-temperature sensors and actuators without input energy. The bi-metal fins14guide the coolant31flow to a respective lower channel30(e.g., low-drag lower channel30) when the surface temperature of top wall18is low or decreased, and guide the coolant31flow to a respective upper channel32when the surface temperature of top wall18is high or increased.

The lower channels30can operate as bypass channels for coolant31. In example embodiments, the deformation of the bi-metal fins14changes the cross-sectional area of each respective upper and lower channels30,32(e.g., mini-channels30,32). Due to such adaptive geometry of each bi-metal fin14, the coolant31flow faces a non-uniform flow blockage through the channels30,32of assembly10, which forces the coolant31flow to make more up and down motions of coolant31through assembly10. Consequently, the internal flow of coolant31through assembly10becomes three-dimensional through assembly10. For example, a decreased flow of coolant31at an upper channel32can remain cold, and increased coolant31flow is then able to reach the respective lower channel30more easily.

The adjustable internal flow-path of coolant31includes two adjustable layers, e.g., the plurality of lower channels30and the plurality of upper channels32. The heat sources of devices12can be plated on or with respect to the top wall18.

The L-shaped or C-shaped bi-metal fins14can be mounted on or with respect to the top wall18for the local coolant31flow control. The cross-sectional area of each respective channel30,32thereby varies due to the deformation of the bi-metal fins14.

For example and as shown inFIG.2, when the top wall18temperature increases at a specific area of the top wall18, the bottom wall portion36of each respective bi-metal fin14proximal to such area bends down and increases the cross-sectional area of such respective upper channel32, thereby increasing the amount of coolant31through such respective upper channel32.

Moreover and as shown inFIG.2, when the top wall18temperature decreases at a specific area of the top wall18, the bottom wall portion36of each respective bi-metal fin14proximal to such area bends up and decreases the cross-sectional area of such respective upper channel32, thereby decreasing the amount of coolant31through such respective upper channel32.

In example embodiments and as shown inFIG.2, when the top wall18is at a neutral temperature (e.g., room temperature of about 20° C.), the bi-metal fins14are in a neutral position, and the bottom wall portion36can be substantially planar or horizontal.

It is noted that due to the viscous effect of coolant31proximal to wall18,20, the flow resistance and flow rate of coolant31can be determined by the respective channel30,32cross-sectional area.

The adaptation or adjustment of each channel30,32cross-sectional area allows the coolant31flow path to be determined/adjusted (e.g., between a dominant layer of lower channel30flows and a dominant layer of upper channel32flows.

It is noted that specific metals for the bi-metal fins14can be selected according to the coolant31and/or top wall18temperatures.

In example embodiments, the width of each flow channel30,32can be smaller than the size of the respective heat source from devices12(e.g., GaN and/or SiC devices12).

There are many benefits of the assemblies10and associated systems/methods, including, without limitation: increased coolant flow can be concentrated to a locally hot area, which can effectively cool the specific area; assembly10can prevent over-cooling by partially blocking the upper channels32when the surface of wall18is too cold; and/or due to the benefit of the bi-metal fins14, no power input is needed for temperature sensing and flow actuating of assembly10.

FIG.3is a side perspective view of another example cooling assembly100, according to the present disclosure. Similar to the assembly10ofFIG.1, example cooling assembly100can take the form of a mini-channel cold plate cooling assembly100for semiconductor devices12(e.g., wide-bandgap (WBG) power semiconductor devices12), with the cooling assembly100utilizing three-dimensional adaptive flow-paths using bi-metal fins114.

FIG.4is an exploded view of the cooling assembly100ofFIG.3.

Similar to assembly10, the example cooling assembly100includes cold plate side walls116A-116D, a cold plate top wall118, and a cold plate bottom wall120(e.g., aluminum cold plate walls116A-116D,118and120).

The semiconductor devices112of assembly100can be positioned on a substrate122(e.g., printed circuit board (PCB)122or ceramic plate122). In example embodiments, each semiconductor device112is a wide band gap device12(e.g., GaN device112, SiC MOSFET device112, etc.). The substrate122can be positioned on the cold plate top wall118. Side wall116A can include a coolant inlet124for coolant131, and side wall116D can include a coolant outlet126for coolant131.

In example embodiments and as shown inFIG.3, a plurality of bi-metal fins114can extend from the top wall118.

In certain embodiments, each bi-metal fin114includes a first section138A of first metal material138, a first section140A of second metal material140, a second section138B of first metal material138, and a second section140B of second metal material140.

The first section138A can be secured to first section140A (e.g., via adhesive or bonding material or the like), and the second section138B can be secured to second section140B (e.g., via adhesive or bonding material or the like).

Each bi-metal fin114can be secured or mounted with respect to the top wall118, with each fin114extending from the wall118. In some embodiments, it is noted that fins114may not be secured to bottom wall120.

After securing fins114to wall118, the first and second sections140A,140B of second metal material140are positioned proximal to one another.

FIG.7is a cross-sectional side view of cooling assembly100where each bi-metal fin114is in the neutral position. In some embodiments, each bi-metal fin114is substantially flat in the neutral position (e.g., the coolant131temperature equals the room temperature of assembly100). In other embodiments, it is noted that each bi-metal fin114has a very small elongated O-shaped gap in the middle area between first and second sections140A,140B in the neutral position, as discussed below. It is noted that the temperature of the flat formation of bi-metal fins114can be determined by the coolant131temperature.

For example, when the coolant131temperature is the same as the room temperature of assembly100, the metal material first sections138A,140A are the same length (e.g., length from wall118towards wall120), and second sections138B,140B are the same length. However, when there is colder or hotter coolant131relative to room temperature of assembly100, one of the metal materials138,140should be shorter than other metal material. This means that the bi-metal fin114can be flat when the coolant131temperature is the same as the room temperature of assembly100. However, it is noted that for considering an effective flow and pressure control of assembly100, the initial formation of fins114(e.g., when the coolant131temperature is the same as the room temperature) can be very slightly elongated O-shaped in the middle area between first and second sections140A,140B.

As shown inFIGS.8and10, when the temperature of the coolant131surrounding a bi-metal fin114is increased (e.g., via device112relative to wall118), sections138A,138B,140A,140B of both metal materials138,140of fin144are curved, thereby forming elongated O-shaped gap142in the middle area between first and second sections140A,140B of fin114. This gap142allows more coolant131to flow through this hot area of assembly100. Thus, the cooling performance of assembly100can be improved by flowing more coolant through gaps142of fins114proximal to hot areas of assembly100, to cool such hot areas. When the coolant131returns close or to room temperature of assembly, the fins114return to the neutral position as discussed above.

The material selection for fins114can be as follows. For deformation of fins114, the change in length can be determined by the bi-metal thickness of the fins114, the thermal expansion coefficient of the materials138,140, and the temperature difference between the bi-metal fin114and the coolant131. It is noted that sections138A and140A are securely bonded to one another, and sections138B and140B are securely bonded to one another. It is also noted that the thermal expansion coefficient of the materials138,140can be a design factor for developing the elongated O-shaped gap142of fins114.

After analysis of the thermal expansion coefficients of the materials138,140, it is noted that Al is a good candidate for thermal expansion, and Ti or Ni is less thermally expansive than Al. Thus, Al and Ni, or Al and Ti are good combinations for materials138,140to form the elongated O-shaped gap142of fins114, as discussed above.

There are many benefits of the assemblies100and associated systems/methods, including, without limitation: increased coolant flow can be concentrated to a locally hot area, which can effectively cool the specific area; assembly100can prevent over-cooling by partially blocking areas when the surface of wall118is too cold; and/or due to the benefit of the bi-metal fins114, no power input is needed for temperature sensing and flow actuating of assembly100.

It is noted that at least a portion of the example assemblies10,100and/or the bi-metal fins14,114can be utilized for refrigerant cooling (e.g., temperatures of 3 to 5° C. (37 to 41° F.) and/or for cryogenic cooling (e.g., cryogenic temperatures below 120 K (−153° C.)).

While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or may be presently unforeseen may arise to applicants or others skilled in the art. Accordingly, the appended claims as filed and as they may be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.

The ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other (e.g., ranges of “up to 25 wt. %, or, more specifically, 5 wt. % to 20 wt. %”, is inclusive of the endpoints and all intermediate values of the ranges of “5 wt. % to 25 wt. %,” etc.). “Combinations” is inclusive of blends, mixtures, alloys, reaction products, and the like. The terms “first,” “second,” and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms “a” and “an” and “the” do not denote a limitation of quantity and are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. “Or” means “and/or” unless clearly stated otherwise. Reference throughout the specification to “some embodiments”, “an embodiment”, and so forth, means that a particular element described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments. A “combination thereof” is open and includes any combination comprising at least one of the listed components or properties optionally together with a like or equivalent component or property not listed.

Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of skill in the art to which this application belongs. All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

Although the systems and methods of the present disclosure have been described with reference to example embodiments thereof, the present disclosure is not limited to such example embodiments and/or implementations. Rather, the systems and methods of the present disclosure are susceptible to many implementations and applications, as will be readily apparent to persons skilled in the art from the disclosure hereof. The present disclosure expressly encompasses such modifications, enhancements and/or variations of the disclosed embodiments. Since many changes could be made in the above construction and many widely different embodiments of this disclosure could be made without departing from the scope thereof, it is intended that all matter contained in the drawings and specification shall be interpreted as illustrative and not in a limiting sense. Additional modifications, changes, and substitutions are intended in the foregoing disclosure. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the disclosure.