Patent Application
20220230938
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.
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' 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.
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
In the illustrated configuration of
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
In some embodiments, the planar power module 14 of
As described in detail herein, the planar power module 14 shown in
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
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
Referring briefly to
The manifold housing 16 shown in
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
The first jet impingement plate 25 of
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
With respect to the respective first and second jet impingement plates 25 and 125 of
Referring briefly to
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
Referring to
An alternative configuration to the embodiment of
Recovery of heated coolant 20 in the embodiment of
Yet another embodiment of the power module assembly 10 is shown in
The coolant inlet slots 50A of
Referring now to
Block B104 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→M1 in
With respect to the sacrificial material used in block B104, 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
In some embodiments, the sacrificial material used as part of block B104 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 B104 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 B106, which is arrived at from block B104 upon the solidifying or hardening of the sacrificial material at block B104, 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→M2”. The method 100 proceeds to block B108 once this sequence is complete.
Block B108 entails injecting a dielectric polymer molding material into the second mold to thereby form the manifold housing 16 of
With respect to the manifold housing 16 shown in
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 B110, the method 100 next includes removing the power module assembly 10 of
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
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.
