Patent Description:
Power electronics refers to the application of solid-state electronics related to the control and conversion of electrical power. This conversion is typically performed by silicon, silicon carbide, and gallium nitride as well as other semiconductor devices that are packaged into power modules. One of the factors associated with power modules is the generation of heat due to electrical power conversion inefficiency. While the heat generated by the power modules is due to many factors, it generally relates an efficiency loss, typically generated as heat. Increased temperatures can result in a reduction in the reliability of the power module performance.

An additional factor for thermal management relates to the packaging of several devices in small form factors. The power density, at which the devices, and thus the module can reliably operate; therefore, depends on the ability to remove this generated heat. The common form of thermal management of power electronics is through heat sinks. Heat sinks operate by transferring the heat away from the heat source of the power module, thereby maintaining the heat source at a lower relative temperature. There are various types of heat sinks known in the thermal management field including air-cooled and liquid-cooled devices as well as phase change devices to ride out transient heat dissipations.

One example of the thermal management of a power module includes the attachment of a heat sink with embedded passages (tubes) to provide liquid cooling of the power module. The heat sink is typically a metallic structure, such as aluminum or copper. A cooling medium is passed through the tubes to cool the power module. The heat sink is typically coupled to the power module base with a thermal interface material (TIM) dispersed there between. The thermal interface material may comprise thermal greases, compliant thermal pads, phase change materials, or the like. <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, and <CIT> discloses cooling arrangements in which one or more heat sinks carrying power component is/are fitted to recesses in a carrier plate through which cooling liquid flows.

In one aspect, the present disclosure relates to a cold plate assembly for an electronic component as defined in the accompanying claims.

In another aspect, the present disclosure relates to a method of forming a cold plate for an electronic component as defined in the accompanying claims.

Aspects of the disclosure described herein are directed to a cold plate assembly for an electronic component where the cold plate assembly has multiple components including a polymer base. For purposes of illustration, the present disclosure will be described with respect to a cold plate assembly for cooling a power module. It will be understood, however, that aspects of the disclosure described herein are not so limited and may have general applicability within the field of electronics.

All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, forward, aft, etc.) are only used for identification purposes to aid the reader's understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of aspects of the disclosure described herein. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and can include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to one another. The exemplary drawings are for purposes of illustration only and the relative dimensions, positions, order and relative sizes reflected in the drawings attached hereto can vary. As used herein, the term "set" or a "set" of elements can be any number of elements, including only one.

<FIG> schematically illustrates an aircraft <NUM> with an avionics system <NUM>, illustrated as an on-board electronics chassis <NUM> (shown in phantom) for housing avionics or avionic components for use in the operation of the aircraft <NUM>. It will be understood that the avionics system <NUM> can include a thermal management member having heat spreaders, heat sinks, heat exchangers, radiators, or heat pipes in non-limiting examples. The electronics chassis <NUM> can house a variety of power modules for avionics electronic components and protects against contaminants, electromagnetic interference (EMI), radio frequency interference (RFI), vibrations, shock and the like. Alternatively, or additionally, the electronics chassis <NUM> can have a variety of avionics mounted thereon. It will be understood that the electronics chassis <NUM> can be located anywhere within the aircraft <NUM>, not just the nose as illustrated.

While illustrated in a commercial airliner, the electronics chassis <NUM> can be used in any type of aircraft, for example, without limitation, fixed-wing, rotating-wing, rocket, commercial aircraft, personal aircraft, and military aircraft. Furthermore, aspects of the disclosure are not limited only to aircraft aspects, and can be included in other mobile and stationary configurations. Non-limiting example mobile configurations can include ground-based, water-based, or additional air-based vehicles.

<FIG> is a cold plate assembly <NUM> including a base plate formed from a polymer and herein referred to as a polymer base <NUM>, and at least one heat sink, or metal adapter <NUM>, illustrated as three metal adapters. An electronic component <NUM> and a substrate <NUM> can be mounted to the metal adapter <NUM>. It should be understood that more or less metal adapters <NUM> can be part of the cold plate assembly <NUM> and more or less electronic components can be mounted to the metal adapter <NUM>.

In an aspect of the disclosure herein the electronic component <NUM> is standardized such as a commercial off the shelf (COTS) part so that the shape, holes, and features of the electronic component <NUM> are matched to the metal adapter <NUM>. Non-limiting examples of the electronic component <NUM> can include insulated gate bipolar Transistors (IGBT), metal oxide semiconductor field effect transistors (MOSFET), diodes, metal semiconductor field effect transistors (MESFET), and high electron mobility transistors (HEMT) used for applications not limited to avionics applications, automotive and sea applications, oil and gas applications, medical, or the like. According to aspects of the disclosure herein, the electronic component <NUM> can be manufactured from a variety of semiconductors, non-limiting examples of which include as example silicon, silicon carbide, gallium nitride, or gallium arsenide. The electronic component <NUM> can generate steady-state or transient heat loads during operation. The cold plate assembly <NUM> is mounted to a polymer base <NUM>. The cold plate assembly <NUM> can be located in the electronics chassis <NUM> (<FIG>).

The substrate <NUM> can be provided to avoid electrical short circuits and to perform heat exchange between the metal adapter <NUM> and the electronic component <NUM>. The substrate <NUM> can be an electrically isolating and thermally conductive layer, such as a ceramic layer. Non-limiting examples of the ceramic layer can include aluminum oxide, aluminum nitride, beryllium oxide, and silicon nitride. In one non-limiting example, the metal adapter <NUM> can be directly bonded to the substrate <NUM>. The substrate <NUM> can be coupled to the metal adapter <NUM> and the electronic component <NUM> using a number of techniques, including but not limited to, brazing, diffusion bonding, soldering, pressure contact such as clamping to provide a simple assembly process, or bonding with a thin layer of thermal interface material (TIM). The TIM optimizes the contact interface between solid components by increasing conduction heat transfer between the components and reducing the effect of thermal expansion between the components with dissimilar coefficient of thermal expansion It should be noted herein that the exemplary arrangement described with respect to <FIG> is for illustrative purposes only and not meant to be limiting.

The polymer base <NUM> can be formed to include at least one mounting aperture <NUM> to enable the metal adapter <NUM> to be affixed to polymer base <NUM> at corresponding metal adapter holes <NUM>, by way of non-limiting example with bolts <NUM>. The manner in which the metal adapter <NUM> coupled to the polymer base <NUM> enables direct cooling to the metal adapter <NUM> from cooling fluid within the polymer base <NUM>. Contact between the metal adapter <NUM> and the polymer base <NUM> can improve thermal dissipation of the cold plate assembly <NUM>.

The polymer base <NUM> can be additively manufactured. An additive manufacturing (AM) process is where a component is built layer-by-layer by successive deposition of material. AM is an appropriate name to describe the technologies that build 3D objects by adding layer-upon-layer of material, whether the material is metal or non-metal. AM technologies can utilize a computer, 3D modeling software (Computer Aided Design or CAD), machine equipment, and layering material. Once a CAD sketch is produced, the AM equipment can read in data from the CAD file and lay down or add successive layers of liquid, powder, sheet material or other material, in a layer-upon-layer fashion to fabricate a 3D object. It should be understood that the term "additive manufacturing" encompasses many technologies including subsets like 3D Printing, Rapid Prototyping (RP), Direct Digital Manufacturing (DDM), layered manufacturing and additive fabrication. Non-limiting examples of additive manufacturing that can be utilized to form an additively-manufactured component include powder bed fusion, vat photopolymerization, binder jetting, material extrusion, directed energy deposition, material jetting, electric pulses through a laser induced plasma channel, or sheet lamination. Other manufacturing techniques can be considered such as molding. In addition, after forming the cold plate, the polymer base <NUM> can be plated with a base metal such as nickel or another metal. The metallic plating can form a leak proof polymer base <NUM>. It should be understood that various types of plating methods can be utilized to plate the polymer base <NUM>.

A cooling manifold <NUM> having a coolant passage <NUM>, illustrated in phantom, can be provided within the polymer base <NUM> and includes an inlet <NUM> and an outlet <NUM>. An upper surface <NUM> can define a first cooling interface <NUM> of the polymer base <NUM>. The first cooling interface <NUM> can be is fluidly coupled to the coolant passage <NUM>, by way of non-limiting example, via at least one recess <NUM>, illustrated as multiple recesses <NUM>, within the upper surface <NUM>. A first structure <NUM>, by way of non-limiting example a plurality of channels <NUM> can be formed in the at least one recess <NUM>. The plurality of channels <NUM> can be formed from a set of walls <NUM>, arranged in any desired pattern, such as a zig-zag pattern as illustrated. The at least one recess <NUM> can further include a periphery groove <NUM> in which an elastomeric seal <NUM> can be received. By way of non-limiting example the elastomeric seal <NUM> can be a gasket or O-ring.

A lower surface <NUM> of the metal adapter <NUM> faces the polymer base <NUM> when assembled. The lower surface <NUM> can define a second cooling interface <NUM> for mating with the first cooling interface <NUM>. A second structure <NUM> can be formed on the second cooling interface <NUM>. By way of non-limiting example, the second structure is a set of fins <NUM> extending from the lower surface <NUM> and defining at least a portion of the second cooling interface <NUM>. When assembled, the second structure <NUM> can be received within the at least one recess <NUM>. Together, the first and second structures <NUM>, <NUM>, illustrated as the plurality of channels <NUM> and the set of fins <NUM>, can form interconnected channels <NUM>, which can be microchannels. An upper surface <NUM> of the metal adapter <NUM> can be flat and smooth.

Turning to <FIG>, a schematic top view of the polymer base <NUM> more clearly illustrates the interconnected channels <NUM> formed. The set of walls <NUM> cross and the set of fins <NUM> (illustrated in phantom) can be oriented orthogonally with respect to each other. While illustrated in this manner, it should be understood that the set of walls <NUM> and the set of fins <NUM> can intersect each other at any angle.

The coolant passage <NUM> can include an inlet plenum <NUM> fluidly coupling the inlet <NUM> to the at least one recess <NUM> via at least one connecting channel <NUM>, more specifically an inlet connecting channel 46a. The coolant passage <NUM> can further include an outlet plenum <NUM> fluidly coupling the outlet <NUM> to at least one recess <NUM> via an additional connecting channel <NUM>, more specifically an outlet connecting channel 46b. While illustrated as generally orthogonally oriented with respect to each other, it should be understood that the inlet plenum <NUM> and the outlet plenum <NUM> can be fluidly coupled via the connecting channels 46a, 46b at any orientation.

In an aspect of the disclosure herein, a cooling fluid (C) flows through the plurality of channels <NUM> to cool the cold plate assembly <NUM>. The cooling fluid (C) can be any suitable cooling fluid, by way of non-limiting example a mixture of propylene glycol and water. Preferably, the cooling fluid (C) can include <NUM> percent by weight of propylene glycol and <NUM> percent by weight of water. The cooling fluid (C) can also include other electrically conductive or non-electrically conductive liquids. It is further contemplated that the cooling fluid (C) can include a gaseous medium or a phase change (liquid-to-vapor or viscous-solid-to-liquid). Accordingly, when the electronic component <NUM> and the metal adapter <NUM> are disposed on the polymer base <NUM>, the cooling fluid (C) flowing through the cooling manifold <NUM> of the polymer base <NUM> provides cooling to the electronic component <NUM>.

A method <NUM> for cooling the cold plate assembly <NUM> can include introducing a cooling fluid flow at <NUM>, by way of non-limiting example the cooling fluid (C) as described herein, through the at least one inlet <NUM> of the polymer base <NUM>. At <NUM> flowing the cooling fluid (C) through the cooling manifold <NUM> and at <NUM> distributing the cooling fluid flow (C) between the polymer base <NUM> and the metal adapter <NUM>. Distribution of the cooling fluid flow (C) between the polymer base <NUM> and the metal adapter <NUM> can occur as the cooling fluid flow (C) flows through the interconnected channels <NUM> formed by the plurality of channels <NUM> and the set of fins <NUM>. The method further includes at <NUM> exhausting the cooling fluid flow (C) from the at least one outlet <NUM>. It should be understood that the cooling fluid flow (C) that is exhausted from the at least one outlet <NUM> is relatively hotter than the cooling fluid flow (C) that was introduced to the at least one inlet <NUM> due to a heat exchange between the metal adapter <NUM> and the polymer base <NUM>. The cold plate assembly <NUM> is therefore cooled. The method can further include distributing the cooling fluid (C) to the plurality of channels <NUM> via the inlet connecting channels 46a and draining the cooling fluid (C) via the outlet connecting channels 46b.

<FIG> is a flow chart illustrating a method <NUM> of forming the cold plate assembly <NUM> including at <NUM> manufacturing the polymer base <NUM> with the cooling manifold <NUM> having an inlet <NUM> and an outlet <NUM> extending between the coolant passage <NUM> and with the first cooling interface <NUM>. At <NUM> manufacturing the metal adapter <NUM> with the second cooling interface <NUM> configured to mount the electronic component <NUM>. At <NUM> mating the second cooling interface <NUM> with the first cooling interface <NUM>. The cooling manifold <NUM> can be designed to minimize pressure drop due to hydraulic loses related to inlet, outlet, and bend as well as frictional losses and hydraulic diameter considerations.

Additionally, the method <NUM> can include forming the at least one recess <NUM> and forming a set of walls <NUM> within the at least one recess <NUM> to form the plurality of channels <NUM>. By way of non-limiting example, the set of walls <NUM> can be formed in a zig-zag pattern. Also, forming the set of fins <NUM> to extend from the second cooling interface <NUM> and be received in the at least one recess <NUM> to form the interconnected channels <NUM>. The metal adapter <NUM> can be formed with a smooth and flat upper surface <NUM>. When assembled, the elastomeric seal can prevent leaking from the cooling manifold <NUM> between the upper surface <NUM> and the lower surface <NUM>. It is further contemplated that the method <NUM> can include plating the cold plate assembly <NUM> as described herein to further mitigate leaking. The polymer base <NUM> of the cold plate assembly <NUM> can be plated with a metal such as nickel to avoid cold plate leakage vis-a-vis the porous nature of additive manufacturing.

<FIG> is a cold plate assembly 10a similar to cold plate assembly <NUM> in both form and function as described herein. Cold plate assembly 10a includes multiple pairs of recesses 32a, 32b formed in a polymer base 12a, and at least one heat sink, or metal adapter 14a, illustrated as three metal adapters each having a pair of sets of fins 40a, 40b extending from the lower surface <NUM> of the metal adapter 14a. The pair of sets of fins 40a, 40b face the polymer base 12a when assembled. When assembled the pair of sets of fins 40a, 40b can be received within the corresponding pair of recesses 32a, 32b. While one pair of recesses 32a, 32b and one pair of sets of fins 40a, 40b are illustrated. It should be understood that two additional pairs are located in the exemplary cold plate assembly 10a beneath the additional metal adapters 14a illustrated.

It should be understood that the method <NUM> as described herein can further include cooling via the pair of recesses 32a, 32b and the pair of sets of fins 40a, 40b. It is therefore contemplated that an intermediate connecting channel 46c can fluidly couple the pair of recesses 32a, 32b enabling the cooling fluid (C) as described herein to flow between the plurality of channels <NUM> formed in the corresponding recesses 32a, 32b.

Furthermore, the method <NUM> can include forming the multiple recesses 32a, 32b and the multiple sets of fins 40a, 40b as illustrated in <FIG>.

<FIG> is a cross-section taken along line VI-VI of <FIG> to more clearly illustrate the arrangement of the polymer base 12a and metal adapter 14a when assembled. It should be understood that a cross-sectional view of the cold plate assembly <NUM> would be similar. The cooling fluid flow (C) can flow along the set of walls <NUM> and is distributed into the pair of set of fins 40a, 40b cooling the metal adapter <NUM>. It can also more clearly be seen that the cooling fluid flow (C) flows between the pair of recesses 32a, 32b via the intermediate connecting channel 46c.

Turning to <FIG>, another cold plate assembly <NUM> is illustrated. The cold plate assembly <NUM> is similar to the cold plate assembly <NUM>, therefore, like parts will be identified with like numerals increased by <NUM>, with it being understood that the description of the like parts of the cold plate assembly <NUM> applies to the cold plate assembly <NUM>, unless otherwise noted.

The cold plate assembly <NUM> includes a polymer base <NUM> and a metal adapter <NUM>, illustrated as three metal adapters. A power module <NUM> including a power module baseplate <NUM> can be mounted to the metal adapter <NUM>. The baseplate <NUM> can be made of a metal or metal matrix composite (MMC). The MMC can include but is not limited to aluminum, copper, aluminum-SiC, aluminum-graphite. The baseplate <NUM> can have a matched coefficient of thermal expansion with electronic component that results in a reliable thermal stress over thermal cycle. The polymer base <NUM> can be additively manufactured.

A cooling manifold <NUM> having a coolant passage <NUM>, illustrated in phantom, can be provided within the polymer base <NUM> and includes an inlet <NUM> and an outlet <NUM>. An upper surface <NUM> can define a first cooling interface <NUM> of the polymer base <NUM>. The first cooling interface <NUM> can be fluidly coupled to the coolant passage <NUM>, by way of non-limiting example, via a set of base slots <NUM> formed within the polymer base <NUM> and fluidly coupled to the coolant passage <NUM>. While illustrated as four base slots, it should be understood that more or less base slots can be part of the set of base slots <NUM> including only one. A lip <NUM> is formed in the upper surface <NUM> of the polymer base <NUM> for receiving the metal adapter <NUM>. The lip <NUM> can prevent the metal adapter <NUM> from moving or sliding during assembly. Fasteners, by way of non-limiting example bolts <NUM>, can hold the power module to the metal adapter <NUM> and the polymer base <NUM>.

The metal adapter <NUM> can extend between a lower surface <NUM> facing the polymer base <NUM> and an upper surface <NUM>. The lower surface <NUM> can define a second cooling interface <NUM> for mating with the first cooling interface <NUM>. A set of adapter slots <NUM> can be formed on the second cooling interface <NUM> and extend at least partially through toward the upper surface <NUM> of the metal adapter <NUM>. The set of adapter slots <NUM> aligns with the set of base slots <NUM> when assembled. An interconnected set of microchannels <NUM> can be formed in the upper surface <NUM> of the metal adapter <NUM> and be fluidly coupled to the set of adapter slots <NUM>. The interconnected set of microchannels <NUM> can be formed as a pair of interconnected sets of microchannels <NUM> as illustrated. While illustrated as a pair of interconnected sets of microchannels <NUM>, it should be understood that more or less interconnected sets of microchannels can be part of the interconnected set of microchannels <NUM> including only one.

The interconnected set of microchannels <NUM> can include a set of orthogonal channels <NUM>, with varying depths. By way of non-limiting example, the sets of orthogonal channels <NUM> can have a maximum depth on one side of the metal adapter <NUM> and as the set of orthogonal channels <NUM> approaches another side of the metal adapter the depth decreases. It is contemplated that the sets of orthogonal channels <NUM> are fluidly connected to the set of adapter slots <NUM>. It is contemplated that the set of orthogonal channels <NUM> are alternating sets such that every other channel is fluidly coupled to a different adapter slot <NUM>.

A set of parallel channels <NUM> can intersect with the set of orthogonal channels <NUM> to form the interconnected set of microchannels <NUM>. In aspects of the disclosure herein, the interconnected set of microchannels <NUM> can have a rectangular or square cross-section. Non-limiting examples of the cross-sectional area shape of the interconnected set of microchannels <NUM> can include circular, triangular, trapezoidal, and u-shaped cross-sections. The interconnected set of microchannels <NUM> can be cast, machined, 3D printed, or etched, and can be smooth or rough in the cooling adapter <NUM>. Roughened channels can have a relatively large surface area to enhance turbulence of the cooling fluid so as to augment thermal transfer therein. In non-limiting examples, the interconnected set of microchannels <NUM> can include features such as dimples, bumps, or the like to increase the roughness thereof. Furthermore, the geometry of the adapter slots <NUM> and the interconnected set of microchannels <NUM> can be designed based on the application, type of cooling medium used, and the ambient temperature. The number of channels can vary depending on the application.

The interconnected set of microchannels <NUM> as described herein are given a more complete exemplary description with regards to geometry in <CIT> referred to therein as a plurality of channels in a manifold plane.

The method <NUM> as described herein can further include forming the set of base slots <NUM> within the polymer base <NUM> to fluidly couple the metal adapter <NUM> to the coolant passage <NUM>. The set of adapter slots <NUM> can be formed on the second cooling interface <NUM> and extend at least partially through the at least one metal adapter <NUM>. The interconnected set of microchannels <NUM> can be formed in the upper surface <NUM> of the metal adapter <NUM> to be fluidly coupled to the set of adapter slots <NUM> to form a cooling fluid passageway <NUM> (<FIG>) between the set of base slots <NUM> and the metal adapter <NUM>.

Turning to <FIG> a cross-section taken along line VIII-VIII of <FIG> more clearly illustrates the arrangement of the polymer base <NUM> and metal adapter <NUM> when assembled. Additionally, the variation of depth as the set of orthogonal channels <NUM> extends between sequential adapter slots <NUM> is more clearly evident. A cooling fluid passageway <NUM> is formed between the coolant passage <NUM> and the metal adapter <NUM> when the set of base slots <NUM> aligns with the set of adapter slots <NUM>. The method <NUM> as described herein can include flowing the cooling fluid flow (C) through the cooling fluid passageway <NUM>. The method <NUM> can further include redistributing the cooling fluid flow (C) among the interconnected set of microchannels <NUM>. As is illustrated, the cooling fluid flow (C) can flow between the polymer base <NUM> and the metal adapter <NUM> via the cooling fluid passageways <NUM> multiple times, first from the polymer base <NUM> to the metal adapter <NUM> and then from the metal adapter <NUM> to the polymer base <NUM> and then back into the metal adapter <NUM> before finally returning to the polymer base <NUM> and exhausting via the outlet <NUM>.

The method <NUM> can further include forming the set of base slots <NUM> within the polymer base <NUM> to fluidly couple the metal adapter <NUM> to the coolant passage <NUM>. The set of adapter slots <NUM> can be formed on the second cooling interface that extend at least partially through the at least one metal adapter. The interconnected set of microchannels <NUM> can be formed in the upper surface <NUM> of the metal adapter <NUM> to be fluidly coupled to the set of adapter slots <NUM>. It is further contemplated that the lip <NUM> is formed in the upper surface <NUM> of the polymer base <NUM> for receiving the metal adapter <NUM>.

Utilizing the cold plate as described herein provides cost savings when compared to machined cold plates. Unlike cold plates manufactured completely from metal components, the cold plate as described herein is a hybrid cold plate that effectively balances material capability with cost and functionality. Short lead times are required for additively manufacturing polymer base which also enables a lighter weight cold plate. In avionics weight decrease is advantageous for fuel efficiency.

Another benefit associated with the polymer base and metal adapter as described herein is the interchangeability of the polymer base and metal adapter with existing cold plates. In this respect, the cooling adapter can be used to replace portions of a cold plate without having to replace an entire power module. This provides an added cost benefit.

Claim 1:
A cold plate assembly (<NUM>, 10a, <NUM>) for an electronic component (<NUM>) comprising:
a polymer base (<NUM>);
a cooling manifold (<NUM>, <NUM>) comprising a coolant passage (<NUM>, <NUM>) within the polymer base (<NUM>) and having an inlet (<NUM>, <NUM>) and an outlet (<NUM>, <NUM>);
a first cooling interface (<NUM>, <NUM>) located in the polymer base (<NUM>) and fluidly coupled to the coolant passage (<NUM>, <NUM>); and
at least one metal adapter (<NUM>, 14a, <NUM>) having a second cooling interface (<NUM>, <NUM>) mating with the first cooling interface (<NUM>, <NUM>) and configured to mount the electronic component (<NUM>), the first cooling interface (<NUM>, <NUM>) comprising at least one recess (<NUM>, 32a, 32b),
characterized in that the cold plate assembly further comprises:
a first structure (<NUM>) formed in the at least one recess (<NUM>, 32a, 32b); and
a second structure (<NUM>) formed on the second cooling interface (<NUM>, <NUM>) and received within the at least one recess (<NUM>, 32a, 32b),
wherein the first and second structures (<NUM>, <NUM>) together form interconnected channels (<NUM>).