Patent Publication Number: US-2022230938-A1

Title: Power module with vascular jet impingement cooling system

Description:
The present disclosure relates to packaging for a two-sided power semiconductor electronic component, referred to hereinafter as a power module for simplicity. More particularly, the present disclosure related to packaging systems and methodologies for conducting a suitable heat transfer fluid/coolant to one or more major surfaces of such a power module for the purpose of thermal regulation. 
     As appreciated in the art, power modules containing one or more semiconductor switching dies are used in a wide variety of high-voltage electrical systems. For example, a power inverter module is employed within a dual direct current (DC) and alternating current (AC) electrical system. Representative high-voltage electrical systems include electrified powertrains and stationery powerplants in which a DC output voltage from a high-voltage DC battery pack is used to energize one or more phase windings of an electric motor. Power modules are likewise used in DC-DC voltage converters for the purpose of providing an application-suitable DC output voltage. 
     Within a typical power module resides a set of semiconductor switching dies disposed within a multi-layered substrate, with the switching dies housing one or more insulated-gate bipolar transistors (IGBTs), metal-oxide silicon field effect transistors (MOSFETs), power diodes, thyristors, or other application-suitable semiconductor switches. Collectively, the switches of the power module are used to perform a high-speed/high-power switching function of the type noted generally above when converting AC power to DC power, or vice versa. 
     The substrate includes electrically conductive layers that function as electrical connections to the various switching dies. Each substrate is typically constructed of a thermally conductive material to facilitate heat transfer away from the sensitive semiconductor switching components. The transferred heat is then dissipated from external surfaces of the power module. Two-sided cooling may be facilitated using a complimentary two-sided cooling system, for instance by clamping the power module between a pair of opposing cooling jackets and employing thermal interface material at interfacing surfaces between the cooling jacket and power module. However, such an approach may be less than optimal in terms of thermal resistance, weight, and packaging size. 
     SUMMARY 
     A vascular jet cooling system is disclosed herein for use with a planar power module. The present solution employs sacrificial molding and polymer encapsulation of a planar power module to facilitate fabrication of a self-contained manifold housing. Within the manifold housing, jet impingement plates serve as nozzle-based or slot-based coolant jets by directing coolant onto an exposed major surface of the planar power module for the purpose of regulating the temperature thereof. 
     As appreciated in the art, a power module is commonly used as a core component of a power inverter, a direct current-to-direct current (DC-DC) converter, and other types of integrated power conversion systems. Heat is generated during the ongoing high-speed switching operations used to convert an alternating current (AC) input voltage to a DC output voltage, or vice versa, or to convert a DC input voltage to a higher or lower DC output voltage. The low-profile arrangement of a flat/planar power module in particular has the effect of concentrating heat into a smaller volume, with heat radiating from one or both major surfaces of the power module depending on the internal configuration. Thermal management is often a bottleneck to efforts toward decreasing the size of a given power module while increasing its power density. Optional two-sided cooling within the confines of the disclosed manifold housing in accordance with the present teachings is thus directed toward eliminating the above-noted thermal management bottleneck and providing other benefits as described below, with one-sided cooling possible in other configurations. 
     The vascular jet cooling system described herein includes at least one jet impingement plate arranged in a dielectric polymer molding material. A portion of the jet impingement plate is embedded in the polymer molding material to help control the plates&#39; relative position, e.g., using an overmolding process. Different plate configurations, possibly accompanied by incorporation of external cooling fins on the power module, may be used to enhance desirable heat transfer properties within the scope of the disclosure. 
     In a particular embodiment, a power module assembly is disclosed for use with an external coolant supply, with the latter proving a suitable heat transfer fluid, and with the fluid referred to hereinafter as coolant for simplicity. The power module assembly includes a planar power module having oppositely-disposed first and second major surfaces, and a manifold housing encapsulating the planar power module therewithin. The manifold housing defines a coolant inlet port configured to fluidly connect to the coolant supply and receive heat transfer fluid/coolant therefrom, an internal cavity in fluid communication with the inlet port and containing the power module, and a coolant outlet port. The coolant inlet port is in fluid communication with the internal cavity, while the coolant outlet port is configured to connect to the coolant supply and direct the coolant thereto, i.e., upon discharge of heated coolant from the manifold housing. 
     Within the structure of the manifold housing, a jet impingement plate is arranged in the internal cavity adjacent to a major surface. The jet impingement plate is configured to direct the coolant passing through the coolant inlet port onto the major surface. Some configurations could use two such jet impingement plates, i.e., parallel first and second jet impingement plates. In such an embodiment, the first and second jet impingement plates are arranged in the internal cavity adjacent to respective first and second major surfaces, and are configured to direct the coolant passing through the coolant inlet port onto the respective first and second major surfaces. 
     The jet impingement plate may be optionally configured as a nozzle plate, in which case the openings include discrete nozzles. Such nozzles, along a center axis thereof, may be cylindrical, tapered, conical, or of various other profiles as described herein. 
     The vascular jet cooling system may be characterized by an absence of o-rings. 
     Each jet impingement plate may be constructed of metal and co-molded with the dielectric polymer molding material of the manifold housing. The metal may include copper, brass, and/or aluminum in optional embodiments. 
     The jet impingement plate in other embodiments is constructed from the dielectric polymer molding material. The dielectric polymer molding material could include, by way of example, an epoxy-based molding compound, a silicon based-molding compound, or a phenolic based molding compound, or various other materials as set forth herein. 
     A power module assembly is also disclosed herein that includes the above-noted planar power module and the vascular jet cooling system. The planar power module may be constructed as a semiconductor switching device, e.g., a half-bridge inverter, in some configurations. 
     A method for constructing a power module assembly includes, in an exemplary embodiment, positioning the planar power module, a first jet impingement plate, and a second jet impingement plate in a first mold, with the first and second jet impingement plates defining respective sets of openings configured to direct a coolant onto a respective major surface of the power module. The method includes injecting a sacrificial material into the first mold, and removing the planar power module and the first and second jet impingement plates from the first mold after the sacrificial material hardens or solidifies. 
     The method in this embodiment also includes placing the planar power module, the first jet impingement plate, the second jet impingement plate, and the sacrificial material into a second mold, and thereafter injecting a dielectric polymer molding material into the second mold. The dielectric polymer molding material is then allowed to solidify or harden, thereby forming a manifold housing around the planar power module and the jet impingement plates. The method then includes removing the power module assembly from the second mold, and thereafter removing and discarding the sacrificial materials. 
     The above summary does not represent every embodiment or every aspect of this disclosure. Rather, the above features and advantages, and other features and attendant advantages of this disclosure, will be readily apparent from the following detailed description of illustrative examples and modes for carrying out the present disclosure when taken in connection with the accompanying drawings and the appended claims. Moreover, this disclosure expressly includes any and all combinations and sub-combinations of the elements and features presented above and below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic perspective view illustration of a vascular jet cooling system for a planar power module in accordance with an embodiment of the present disclosure. 
         FIG. 1A  is a schematic partial cross-sectional exploded view illustration of the vascular jet cooling system shown in  FIG. 1 . 
         FIG. 2  is a schematic depiction of possible profiles for use in the construction of impingement plates of the vascular jet cooling system shown in  FIG. 1A . 
         FIGS. 3 and 4  are schematic cross-sectional illustrations of the vascular jet cooling system shown in  FIGS. 1 and 2  according to different embodiments. 
         FIG. 5  is a schematic top view illustration of a possible coolant path and nozzle configuration in accordance with a nozzle jet embodiment of the vascular jet cooling system shown in  FIG. 4 . 
         FIG. 6  is a schematic cross-sectional illustration of the vascular jet cooling system shown in  FIGS. 1-5  according to an alternative slot jet embodiment. 
         FIG. 7  is a schematic top view illustration of a possible coolant path and nozzle configuration in accordance with the slot jet embodiment of the vascular jet cooling system shown in  FIG. 6 . 
         FIG. 8  is a flow chart describing a representative embodiment of a method of constructing the vascular jet cooling system of  FIGS. 1-7 . 
         FIG. 9  is a schematic perspective view illustration of optional cooling fins usable as part of the power module contemplated herein. 
     
    
    
     DETAILED DESCRIPTION 
     The present disclosure is susceptible of embodiment in many different forms. Representative examples of the disclosure are shown in the drawings and described herein in detail as non-limiting examples of the disclosed principles. To that end, elements and limitations described in the Abstract, Introduction, Summary, and Detailed Description sections, but not explicitly set forth in the claims, should not be incorporated into the claims, singly or collectively, by implication, inference, or otherwise. 
     For purposes of the present description, unless specifically disclaimed, use of the singular includes the plural and vice versa, the terms “and” and “or” shall be both conjunctive and disjunctive, “any” and “all” shall both mean “any and all”, and the words “including”, “containing”, “comprising”, “having”, and the like shall mean “including without limitation”. Moreover, words of approximation such as “about”, “almost”, “substantially”, “generally”, “approximately”, etc., may be used herein in the sense of “at, near, or nearly at”, or “within 0-5% of”, or “within acceptable manufacturing tolerances”, or logical combinations thereof. 
     Referring to the drawings, wherein like reference numbers refer to like features throughout the several views, an exemplary embodiment of a power module assembly  10  is depicted schematically in  FIGS. 1 and 1A . The power module assembly  10  as set forth herein includes a vascular jet cooling system  12  having a manifold housing  16  and a planar power module  14  encapsulated therewithin, with a representative embodiment of the power module  14  depicted in  FIG. 1A . High-voltage leads  22  and low-voltage gate control pins  24  project radially outward from a manifold housing  16 , i.e., in a generally orthogonal direction relative to a longitudinal axis  11  of the manifold housing  16 . 
     In the illustrated configuration of  FIGS. 1 and 1A , three such high-voltage leads  22  project radially from the planar power module  14 , and are used to connect high-voltage direct current (DC) and alternating current (AC) buses (not shown) to the power module  14 . Three such high-voltage leads  22  are depicted in  FIGS. 1A  projecting from a same or common lateral side  19  of the power module  14  for a representative single phase/half-bridge inverter or other semiconductor switching device embodiment of the power module  14 , and thus the high-voltage leads  22  include a positive (+) and a negative (−) DC high-voltage lead  22 , and a high-voltage AC lead  22 , nominally labeled as U in  FIG. 1 . 
     While “high-voltage” as used herein means “in excess of typical 12-15V auxiliary voltage levels”, e.g., 60V or more, automotive embodiments and other mobile applications typically use voltage levels of 300-400V or more for powering propulsion functions, with such voltage levels being typical high-voltage levels within the scope of the disclosure. Those skilled in the art will appreciate that the present teachings are readily extended to other types of power modules  14 , such as but not limited to multi-phase/full-bridge/6-in-1 type power inverters. For illustrative consistency, a single-phase half-bridge embodiment of the planar power module  14  will be described herein without limiting applications to such a configuration. Other semiconductor switching devices may be used in other embodiments, however, and therefore the half-bridge embodiment is non-limiting and illustrative of the present teachings. 
     The planar power module  14  in a representative embodiment may be configured as a power inverter module for use in a high-voltage electrical system, e.g., an electric powertrain system for a motor vehicle, a powerplant, or another stationary or mobile high-voltage system. As understood in the art and noted generally above, such a power module  14  may include multiple semiconductor switching dies in the form of bipolar transistors, insulated-gate bipolar transistors (IGBTs), metal oxide semiconductor field effect transistors (MOSFETs), thyristors, and/or diodes. Such semiconductor components, not shown but well understood in the art, are encapsulated within the module body  16  as shown in  FIG. 1A  and electrically connected to the high-voltage leads  22  and low-voltage gate control pins  24 . In a typical electrical system, for example that of an electrified vehicle, the high-voltage leads  22  are connected to a propulsion battery pack via positive and negative bus bars, as well as to a corresponding phase winding of a rotary electric machine. Such an electric machine may be embodied as an electric propulsion motor in the example of the electrified motor vehicle. Other stationary or mobile electrical systems may benefit from the power module  14 , and therefore mobile or vehicular applications are exemplary of the present teachings and non-limiting thereof 
     In some embodiments, the planar power module  14  of  FIG. 1  may be of a composite structure, e.g., in the form of a metallized ceramic substrate, which is a ceramic substrate sandwiched between and directly bonded to layers or sheets of metal. The metallized ceramic substrate may be in the form of a direct bonded copper (DBC) or direct bonded aluminum (DBA) ceramic substrate. In either case, the ceramic substrate may be made of a ceramic material, e.g., aluminum-oxide (Al 2 O 3 ), aluminum-nitride (AlN), and/or beryllium oxide (BeO). In DBC ceramic substrates, the ceramic substrate is sandwiched between and directly bonded to layers or sheets of copper (Cu) and/or copper oxide (CuO). In DBA ceramic substrates, the ceramic substrate is sandwiched between and directly bonded to layers or sheets of aluminum (Al). 
     As described in detail herein, the planar power module  14  shown in  FIG. 1A  is encapsulated within and co-molded with a manifold housing  16  of the vascular jet cooling system  12 . An exemplary orientation of the manifold housing  16 , in a representative xyz/Cartesian reference frame, is one in which the longitudinal axis  11  is arranged along the nominal x axis, i.e., lengthwise. A height dimension of the manifold housing  16  is thus arranged along the z-axis, with the y-axis describing the width. 
     The manifold housing  16  includes a coolant inlet port  15  and a coolant outlet port  17 , with the coolant inlet port  15  and the coolant outlet port  17  being coaxially arranged along the longitudinal axis  11  in the exemplary configuration of  FIG. 1 . The orientation and coaxial positioning of the coolant inlet port  15  and the coolant outlet port  17  are enabled due to the high-voltage leads  22  being on the same side of the planar power module  14 . Other embodiments, such as full-bridge or 6-in-1 embodiments of power module  14 , may have multiple AC leads  22  projecting from an adjacent surface of the power module  14 , in which case the coolant inlet port  15  and the coolant outlet port  17  may be positioned above or below the plane of the power module  14 . 
     The coolant inlet port  15  is configured to fluidly connect to a coolant supply  21 , e.g., a reservoir of an application suitable heat transfer fluid/coolant  20 . As part of the disclosed operation of the vascular jet cooling system  12 , the coolant  20  is directed under pressure through the manifold housing  16 , such as by circulation via a coolant pump (not shown). Coolant  20  enters the manifold housing  16  through the coolant inlet port  15 , with the inlet flow direction indicated in  FIG. 1  by arrow II. Heat generated by high-speed switching operations within the planar power module  14  of  FIG. 1A  is transferred to the circulating coolant  20  as the coolant  20  impinges upon the power module  14  and passes through the manifold housing  16 . The heated coolant  20  ultimately exits the manifold housing  16  via the coolant outlet port  17  as indicated in  FIG. 1  by arrow OO. In this manner, the planar power module  14  is cooled by an impingement operation of the vascular jet cooling system  12 . 
     Referring briefly to  FIG. 9 , heat transfer efficiency enabled by the present disclosure may be enhanced by increasing the surface area of the planar power module  14 . For instance, a representative first major surface  30  of the power module  14  may be equipped with surface asperities  70 , exemplified in  FIG. 9  as a set of cooling fins  72 . The cooling fins  72  are spaced apart from each other by troughs  74 , with an even spacing shown for illustrative simplicity. Other surface asperities  70  may be used within the scope of the disclosure, including evenly distributed or unevenly distributed surface roughness, variation in the height and/or width of the cooling fins  72 , etc. Thus, the smooth appearance of the power module  14  in  FIGS. 1 and 1A  is itself exemplary and non-limiting. 
     The manifold housing  16  shown in  FIG. 1A , which is a partial cross-sectional view of the power module assembly  10  shown in  FIG. 1  taken along cut-line AA, is constructed of an electrically insulating/dielectric polymer molding material. Non-limiting exemplary materials of construction include epoxy-based molding compound, a silicon-based molding compound, or a phenolic based molding compound. The manifold housing  16  defines therein an internal cavity  23  in fluid communication with the coolant inlet port  15  of  FIG. 1 . The internal cavity  23 , shown as a generally rectangular chamber bounded by the manifold housing  16 , thus contains the power module  14 . The coolant outlet port  17 , which is in fluid communication with the internal cavity  23 , is configured to connect to the coolant supply  21  of  FIG. 1 , e.g., via a network of clamps, hoses/tubing, valves, etc. In its various embodiments, the vascular jet cooling system  12  of  FIGS. 1 and 1A  may be characterized by an absence of o-rings, with internal sealing occurring solely via integral formation of the constituent components. 
     Within the scope of the present disclosure, the vascular jet cooling system  12  includes at least one jet impingement plate, i.e., one or both of a first jet impingement plate  25  and a separate second jet impingement plate  125 . That is, while two-sided cooling may be used in accordance with the present teachings, e.g., when heat is radiated from the first major surface  30  and the second major surface  130 , embodiments may be contemplated in which one of the first or second major surfaces  30  or  130  is cooled. Those skill in the art will appreciate that one of the jet impingement plates  25  or  125  could be eliminated in such an embodiment, with coolant  20  directed through the remaining jet impingement plate  25  or  130  to cool the respective major surface  30  or  130 . Thus, single-side cooling is possible within the scope of the disclosure. 
     In a non-limiting two-sided cooling configuration as shown, the respective first and second jet impingement plates  25  and  125  are arranged parallel to each other within the internal cavity  23  of the manifold housing  16 . The respective first and second jet impingement plates  25  and  125  are co-molded/overmolded with the manifold housing  16  as described below with particular reference to  FIG. 8 , and constructed of an application-suitable material. In a possible construction, the first and second jet impingement plates  25  and  125  are constructed of metal, such as but not limited to copper, brass, or aluminum. Alternatively, the respective first and second jet impingement plates  25  and  125  may be constructed from a polymer material, which may be the same dielectric polymer molding material used to construct the manifold housing  16 . 
     The first jet impingement plate  25  of  FIG. 1A  defines a first set of openings  26 . As explained below with reference to the remaining Figures, the first set of openings  26  directs coolant  20  passing through the coolant inlet port  15  of  FIG. 1  onto a first major surface  30  of the planar power module  14 . Similarly, the second jet impingement plate  125  defines a second set of openings  126 , with the second set of openings  126  being configured to direct the coolant  20  passing through the coolant inlet port  15  of  FIG. 1  onto a second major surface  130  of the power module  14 . Heat generated from rapid switching of semiconductor switching dies (not shown) located within the power module  14  radiates to the respective first and second major surfaces  30  and  130 , and is transferred to the coolant  20  impinged thereon, with the heated coolant  20  ultimately circulated out of the internal cavity  23  and through the coolant outlet port  17  as the coolant outlet flow (arrow OO). 
     To this end, the internal cavity  23  may be divided into upper and lower cavity chambers  123  and  223 . Upon entering the manifold housing  16  through the coolant inlet port  15  of  FIG. 1 , under pressure from an external battery operated or engine-driven coolant pump (not shown), the coolant  20  passes into the respective upper and lower cavity chambers  123  and  223 . As the upper and lower cavity chambers  123  and  223  are equally sized and equidistant from the planar power module  14  disposed within the internal cavity  23 , coolant flow and heat transfer are approximately equalized across the first and second major surfaces  30  and  130 . 
     With respect to the respective first and second jet impingement plates  25  and  125  of  FIG. 1A , the sets of openings  26  and  126  collectively perform a vascular jet impingement function to radiantly cool the planar power module  14  from both sides, i.e., from its respective first and second major surfaces  30  and  130 . In a possible construction, the first and second jet impingement plates  25  and  125  are embedded in the dielectric polymer molding material of the manifold housing  16 , e.g., via overmolding. While the sets of openings  26  and  126  are shown as circular orifices for illustrative simplicity, those skilled in the art will appreciate that various shapes and configurations of the sets of openings  26  and  126  may be used within the scope of the disclosure to enhance heat transfer. 
     Referring briefly to  FIG. 2 , representative axial profiles  28  are shown for the respective first and second sets of openings  26  and  126 , with the profiles  28  shown relative to the flow direction, i.e., arrows II and OO, which is along a center axis of the various openings  26  and  126 . The profiles  28  may include a twisting or corkscrew-type profile  128  to impart momentum in a transverse direction, possibly enabling improved plume angle and penetration control, or a converging/diverging profile  228  to accelerate then decelerate flow of the coolant  20 . Such a configuration may facilitate control of plume angle and entrainment. Other representative profiles  28  may include a defined complex profile  328  to control cavitation or flow separation, or possibly providing the sets of openings  26  and  126  with a roughness profile  428  to impart a desired degree of turbulence and promote atomization. 
     In still other configurations, the sets of openings  26  and  126  may have an asymmetric profile  528  to enable better mass distribution and flow control, with flow velocity (V)  550  representing such control. Alternatively, the first and second sets of openings  26  and  126  may be provided with a linear geometric transition profile  628  along their respective axes for mass distribution control and improved structural integrity. These and other profiles may be envisioned, with construction of profiles having a high level of geometric complexity enabled using additive manufacturing techniques. 
     As described below, the first and second jet impingement plates  25  and  125  of  FIG. 1A  may be optionally configured as discrete nozzle plates, in which case the sets of openings  26  and  126  are discrete/individual nozzles having one of the profiles  28  of  FIG. 2 , a straight cylindrical profile, or another suitable profile  28 . Example nozzle plate-configurations for the first and second jet impingement plates  25  and  125  are depicted in  FIGS. 3-5  and described in detail below. Alternatively, the first and second jet impingement plates  25  and  125  may be configured as slot plates as shown in  FIGS. 6 and 7 , in which case the respective first and second sets of openings  26  and  126  are constructed as elongated, continuous slots. 
     Referring to  FIG. 3 , the power module assembly  10  is depicted in a schematic cross-sectional view along the indicated xz axes of the above-noted xyz reference frame. Inlet flow (arrow II) of the coolant  20  enters the manifold housing  16  via the coolant inlet port  15 , external structure of which is omitted for clarity but depicted in  FIG. 1 . The coolant  20  divides at a terminal end  31  of the coolant inlet port  15  before passing through the first and second sets of openings  26  and  126  onto the planar power module  14 , abbreviated “PEC” for “power electronic component”, e.g., a half-bridge or full-bridge power inverter module. Heated coolant  20  then exits the manifold housing  16  via the coolant outlet port  17  as outlet flow (arrow OO). A downstream heat exchanger (not shown) could be used to extract the heat and return the coolant  20  to the coolant supply  21  of  FIG. 1  for recirculation to the coolant inlet port  15 , as will be appreciated by those skilled in the art. 
     An alternative configuration to the embodiment of  FIGS. 1-3  is shown in  FIGS. 4 and 5 . Here, the first set of openings  26  is serviced by inlet fluid channels  34 ,  134  that are connected to or integrally formed with a respective coolant manifold  40  and  140 , with a representative configuration of the coolant manifold  40  depicted schematically in  FIG. 5 . Coolant manifold  140 , shown in  FIG. 5 , is representative of the coolant manifold  140 , and therefore is illustrative of the relevant structural features thereof. A similar network of outlet channels  35  and  135  is created for recovering the coolant  20 . While the perspective of  FIG. 4  illustrates the first set of openings  26  used to direct coolant  20  onto the planar power module  14 , similar openings  26  are shown in  FIG. 5  for the purpose of extracting the heated coolant  20 . 
     Recovery of heated coolant  20  in the embodiment of  FIGS. 4 and 5  may be aided by suction or purposeful orientation that favors the heated coolant  20  being directed in the desired manner. Also, while the internal cavity  23  is shown with air pockets to better illustrate injection of a conical jet of coolant  20  and subsequent impingement upon the power module  14 , the internal cavity  23  may be completely filled with coolant  20  in an actual embodiment, depending on the size of the internal cavity  23  and the injection rate of the coolant  20 . 
     Yet another embodiment of the power module assembly  10  is shown in  FIGS. 6 and 7 . Here, the nozzle jet configuration of  FIGS. 2-5  is replaced with a slot plate embodiment of the first and second jet impingement plates  25  and  125  described above, i.e., as slot plates  225 A and  225 B. In the depicted embodiment, coolant  20  enters from a coolant manifold  400 , as indicted at II in  FIG. 6 . A representative configuration of the coolant manifold  400  is depicted in a schematic plan view illustration in  FIG. 7 . The admitted coolant  20  (arrow II) is conducted along the full lengths of the coolant inlet slots  50 A, each being elongated continuous openings as opposed to discrete opening as in the earlier described embodiments, and onto the exposed first major surface  30  of the planar power module  14 . A similar coolant manifold  400  would be positioned to perform the same function for the exposed second major surface  130  of  FIG. 6 . Heated coolant  20  then passes into the adjacent coolant outlet slots  50 B, where the heated coolant  20  ultimately passes out of the manifold housing  16  as outlet flow (arrow OO). 
     The coolant inlet slots  50 A of  FIG. 7  are interspaced with coolant outlet slots  50 B, such that a given coolant inlet slot  50 A is immediately adjacent to a neighboring coolant outlet slot  50 B. As shown in  FIG. 6 , terminal ends of the coolant inlet slots  50 A are thus configured as slot jets  226 A and  226 B, with arrows  45  representing the flow of coolant  20  between coolant inlet slots  50 A and adjacent coolant outlet slots  50 B. Each coolant slot  50 A and  50 B has a generally constant cross-section as shown in  FIG. 6 , with the particular profile of the slot jets  226 A and  226 B increased via a tapered reduction in flow area as shown. As depicted, the coolant slots  50 A and  50 B are constructed from the same dielectric polymer molding material used to construct the manifold housing  16 . In other embodiments, however the coolant slots  50 A and  50 B could be constructed of metal or other suitable materials. 
     Referring now to  FIG. 8 , a method  100  for fabricating the power module assembly  10  shown in the representative embodiment of  FIGS. 1-3  commences, in a representative embodiment, with block B 102 . Block B 102  includes positioning the planar power module  14 , the first jet impingement plate  25 , and the second jet impingement plate  125  in a first mold. As explained above, the respective first and second jet impingement plates  25  and  125  define the sets of openings  26  and  126 , which in turn are configured to direct the coolant  20  onto a respective first or second major surface  30  or  130  of the power module  14 . The sequence of block B 102  is abbreviated in  FIG. 8  as  14 ,  25 ,  125 →M 1 , with M 1  representing the above-noted first mold. As understood in the art, such a mold is configured to support and retain the power module  14  and the first and second jet impingement plates  25  and  125  in a desired relative position prior to a subsequent overmolding or co-molding step. The method  100  proceeds to block B 104  once the components have been placed in this manner. 
     Block B 104  includes injecting a sacrificial material into the first mold. The injected sacrificial material is then allowed to solidify or harden, with this sequence abbreviated SAC MAT→M 1  in  FIG. 8 . The method  100  then proceeds to block B 106 . 
     With respect to the sacrificial material used in block B 104 , such a material or combination thereof may be introduced using compression molding, vacuum forming, thermoforming, injection molding, blow molding, profile extrusion, or a combination thereof. The sacrificial material may be introduced in the form of a liquid or relatively soft material, and may be allowed to solidify or harden within the first mold, e.g., by cooling and/or by curing. The sacrificial material contemplated herein is “sacrificial” in the sense of being removable from the first mold without harming the physical and/or structural integrity of the power module  14  and the first and second jet impingement plates  25  and  125  shown in  FIG. 1A . 
     In some embodiments, the sacrificial material used as part of block B 104  may be a material that exhibits a solid phase at ambient temperature, but upon heating to a temperature less than about 175° C., transitions to a liquid phase or a gas phase. The sacrificial material may be a material that exhibits a solid phase at ambient temperature, but thermally decomposes (e.g., pyrolyzes or oxidizes) upon heating to a temperature greater than ambient temperature but less than 175° C. The sacrificial material may be soluble in an aqueous medium (e.g., water) or a nonaqueous medium (e.g., acetone), or dissolved by a chemical etchant such as an acid, e.g., hydrochloric acid, sulfuric acid, and/or nitric acid. 
     Embodiments of the sacrificial material include a metal alloy solder having a melting point less than 175° C., e.g., a tin-based alloy solder. Combustible materials usable in some embodiments of the sacrificial material in block B 104  include black powder, i.e., a mixture of sulfur, charcoal, and potassium nitrate, pentaerythritol tetranitrate, a combustible metal, a combustible oxide, a thermite, nitrocellulose, pyrocellulose, a flash powder, and/or a smokeless powder. Such combustible materials may have flash points of less than 175° C. Examples of water-soluble materials that may be used for the sacrificial material include inorganic salts and/or metal oxides, e.g., sodium chloride, potassium chloride, potassium carbonate, sodium carbonate, calcium chloride, magnesium chloride, sodium sulphate, magnesium sulfate, and/or calcium oxide. Examples of polymeric materials that may be formulated to thermally decompose at temperatures less than 175° C. and thus may be used for the sacrificial material include polylactic acid (PLA), polyethylene terephthalate (PET), biaxially oriented polyethylene terephthalate (BOPET), cellulose, polypropylene, high density or low density polyethylene (HDPE, LDPE), acrylonitrile butadiene styrene (ABS), poly(alkylene carbonate) copolymers, and combinations thereof 
     Block B 106 , which is arrived at from block B 104  upon the solidifying or hardening of the sacrificial material at block B 104 , entails removing the planar power module  14 , the first jet impingement plate  25 , the second jet impingement plate  125 , with the above-described sacrificial materials still in place. The removed components are thereafter placed into a second mold, a process sequence that is abbreviated “SAC MAT,  14 ,  25 ,  125 →M 2 ”. The method  100  proceeds to block B 108  once this sequence is complete. 
     Block B 108  entails injecting a dielectric polymer molding material into the second mold to thereby form the manifold housing  16  of  FIGS. 1 and 1A , with this sequence abbreviated “INJ PM→M 2 ” in  FIG. 8 . The materials are then allowed to solidify and harden within the second mold, thereby forming the manifold housing  16  around the planar power module  14 , the first jet impingement plate  25 , and the second jet impingement plate  125 . The method  100  proceeds to block B 110  once hardening is complete. 
     With respect to the manifold housing  16  shown in  FIG. 1A , suitable materials of construction may include a thermosetting or a thermoplastic polymeric material in different embodiments. The particular polymer material used for constructing the manifold housing  16  could be introduced into a mold as a liquid or a relatively soft malleable material and allowed to solidify therein by cooling and/or curing. Representative materials of construction of the manifold housing  16  include, but are not limited to, epoxy, silicon, or phenolic as noted above, as well as polyurethane, polyimide, polypropylene, nylon, thermoplastic olefin, polycarbonate, polytetrafluoroethylene, and/or combinations thereof 
     The manifold housing  16  described above may be of a unitary one-piece construction, i.e., formed around the planar power module  14  and the first and second jet impingement plates  25  and  125  in a single manufacturing step. In other embodiments, the manifold housing  16  may be formed as two discrete, symmetrical halves, positioned around the power module  14 , and thereafter bonded to one another using an application-suitable adhesive or sealant, or via ultrasonic welding or weld bonding techniques. The adhesive or sealant used to bond the manifold housing  16  may be constructed of an elastomeric polymeric material cured at room temperature. Such an adhesive/sealant may be a silicon-based polymeric material, e.g., a room-temperature -vulcanizing (RTV) silicone in some embodiments. 
     At block B 110 , the method  100  next includes removing the power module assembly  10  of  FIG. 1  from the second mold, and then removing the sacrificial materials. The end result of block B 110  is the provision of the power module assembly  10 . Removal of the sacrificial materials depends on the particular materials used, with various types described above. Such materials may be water soluble or dissolvable in a particular solvent, for instance, or combustible, frangible, or removable in a host of ways depending on the particular construction, with removal in such embodiments including flushing with the noted water or solvent, application of vibration energy, combustion, etc. Additional machining or finishing techniques may be applied as part of block B 110  to finish the power module assembly  10  as needed, with this sequence abbreviated FNSH ( 10 ) in  FIG. 7 . 
     The present teachings enable construction of a planar power module  14  that can be cooled from both sides by an array of impinging jets, with various examples shown in  FIGS. 1A-7 . The manifold housing  16  shown in the various Figures may support metal or co-molded polymer embodiments of the respective first and second jet impingement plates  25  and  125  of  FIG. 1A , with the manifold housing  16  self-sealing against the power module  14 , i.e., the heat source, to thereby retain coolant  20  within the internal cavity  23 . Self-sealing may be achieved using mechanical pressure, chemical adhesion, or both. Coupled with the various geometries of  FIG. 2  and the alternating channel configurations of  FIGS. 3-7  and the optional external cooling fins  72  of  FIG. 9 , therefore, one may enable two-sided cooling of the power module  14  of FIG.  1 A. These and other benefits will be readily appreciated by those skilled in the art in view of the foregoing disclosure. 
     The detailed description and the drawings or figures are supportive and descriptive of the present teachings, but the scope of the present teachings is defined solely by the claims. While some of the best modes and other embodiments for carrying out the present teachings have been described in detail, various alternative designs and embodiments exist for practicing the present teachings defined in the appended claims. Moreover, this disclosure expressly includes combinations and sub-combinations of the elements and features presented above and below.