Heat-sinked power semiconductor with folded fin heatsink

Abstract

A heat-sinked power semiconductor assembly includes a semiconductor die; a plurality of pin terminals electrically coupled to the semiconductor die; an encapsulant body at least partially enclosing the semiconductor die and the plurality of pin terminals; and a heat sink, coupled to the assembly, comprising a fin set having a plurality of fin members configured to receive a cooling fluid.

Description

HEAT-SINKED POWER SEMICONDUCTOR WITH FOLDED FIN HEATSINKFIELD

[0001] The present disclosure relates to a heat-sinked power semiconductor with a folded fin heatsink.BACKGROUND

[0002] The present disclosure relates to power semiconductors used with rotating electrical machines. The power semiconductors can be used in a variety of applications, such as to invert direct current (DC) electrical power to angularly displace a rotor assembly with relative to a stator assembly of the rotating electrical machine. Inverting DC electrical power can generate significant amounts of heat, which may reduce the operating efficiency of the rotating electrical machine. It would be helpful to cool the power semiconductors.SUMMARY

[0003] In one embodiment of the present disclosure, a heat-sinked power semiconductor assembly includes a semiconductor die; a plurality of pin terminals electrically coupled to the semiconductor die; an encapsulant body at least partially enclosing the semiconductor die and the plurality of pin terminals; and a heat sink, coupled to the assembly, comprising a fin set having a plurality of fin members configured to receive a cooling fluid.

[0004] In one embodiment of the present disclosure, a heat-sinked power semiconductor assembly includes a semiconductor die; a plurality of pin terminals electrically coupled to the semiconductor die; an encapsulant body at least partially enclosing the semiconductor die and the plurality of pin terminals; a heat sink comprising a fin set having a plurality of fin members configured to receive a cooling fluid; and a heat sink base, having a pair of first walls and a pair of second walls, wherein the fin set is received within the pair of first walls and the pair of second walls.

[0005] In one embodiment of the present disclosure, a heat-sinked power semiconductor assembly including a semiconductor die; a plurality of pin terminals electrically coupled to the semiconductor die; an encapsulant body at least partially enclosing the semiconductor die and the plurality of pin terminals; a heat sink, coupled to the assembly, comprising a fin set having a plurality of fin members configured to receive a cooling fluid; a sealing pad, coupled to the fin set, formed from a compressible material; and an inverter mount having a plurality of cavities shaped to receive heat-sinked power semiconductors, the plurality of cavities each having a first side that is non-parallel to a second side opposite the first side, such that the first side engages a surface of the sealing pad and biases the sealing pad into engagement with the fin set.DRAWINGS

[0006] The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.

[0007] Figure 1 is a perspective view of a heat-sinked power semiconductor constructed in accordance with the teachings of the present disclosure;

[0003] Figure 2 is a side elevation view of the heat-sinked power semiconductor of Figure 1 ;

[0009] Figure 3 is a front elevation view of the heat-sinked power semiconductor of Figure 1 ;

[0010] Figure 4 is a perspective view of a portion of the heat-sinked power semiconductor of Figure 1 , illustrating the construction of a power semiconductor in more detail;

[0011] Figure 5 is a perspective view of a portion of the heat-sinked power semiconductor of Figure 1 , illustrating the heat sink in more detail;

[0012] Figure 6 is a side elevation view of the heat sink;

[0013] Figure 7 is a bottom plan views of the heat sink;

[0014] Figure 8 is a perspective view of a portion of an inverter that employs a plurality of the heat-sinked power semiconductors of Figure 1 ;

[0015] Figure 9 is a perspective view of a portion of an inverter that employs a plurality of the heat-sinked power semiconductors of Figure 1 ;

[0016] Figure 10 is an enlarged portion of Figure 9;

[0017] Figure 11 is a perspective view of an implementation of a heat-sinked power semiconductor;

[0018] Figure 12 is a perspective view of an implementation of a portion of a heat-sinked power semiconductor;

[0019] Figure 13 is a perspective view of an implementation of a heat-sinked power semiconductor;

[0020] Figure 14 is a perspective view of an implementation of a heat-sinked power semiconductor;

[0021] Figure 15 is a perspective view of an implementation of a heat-sinked power semiconductor;

[0022] Figure 16 is a perspective view of an implementation of a heat-sinked power semiconductor; and

[0023] Figure 17 is a cross-sectional view of an implementation of a heat- sinked power semiconductor.

[0024] Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.DETAILED DESCRIPTION

[0025] With reference to Figures 1 through 3, an exemplary heat-sinked power semiconductor is generally indicated by reference numeral 10. The heat- sinked power semiconductor 10 can include a power semiconductor 12 and heat sink 14.

[0026] With reference to Figures 1 through 4, the power semiconductor 12 can be any type of power semiconductor, such as a transistor. For example, the power semiconductor 12 could be an Insulated Gate Bipolar Transistor (IGBT), but in the particular example provided is a Metal Oxide Semiconductor Field Effect Transistor (MOSFET). The power semiconductor 12 can include a semiconductor die 20, a plurality of pin terminals 22, a plate terminal 24, and an encapsulant body 26. The semiconductor die 20 can have a plurality of semiconductor terminals (not specifically shown) that are each electrically coupled to an associated one of the pin terminals 22. In the example provided, the semiconductor die 20 has four semiconductor terminals that comprise a gate (not specifically shown), a source sense (not specifically shown), a source (not specifically shown), and a drain (not specifically shown). Each of the pin terminals 22 is formed of an electrically conductive metal material, such as copper, and can be electrically coupled to an associated one of the semiconductor terminals. For example, each of the pin terminals 22 can be bonded to an associated one of the semiconductor terminals with a solder material to thereby electrically and physically couple the pin terminal 22 to the associated one of the semiconductor terminals. Alternatively, one or more bond wires 30 could be employed to electrically couple one of the pin terminals 22 to an associated one of the semiconductor terminals. The plate terminal 24 can be electrically coupled to one of the pin terminals 22 and could be directly mounted to one of the semiconductor terminals. In the example provided, the pin terminal 22a is electrically coupled to the gate, the pin terminal 22b is electrically coupled to the source sense, the pin terminal 22c is electrically coupledto the source, and the pin terminal 22d is electrically coupled to both the drain and the plate terminal 24. The plate terminal 24 is formed of a suitable electrically conductive metal material, such as copper. The encapsulant body 26 is formed of an encapsulant material that is disposed over the semiconductor die 20. The semiconductor die 20 and the bond wires 30 are fully encapsulated in the encapsulant material, and the pin terminals 22 are partly encapsulated in the encapsulant material. Optionally, the plate terminal 24 can be partly encapsulated in the encapsulant material.

[0027] With reference to Figures 5 through 7, the heat sink 14 can have a body or heat sink base 40 and a fin set 42 that is fixedly coupled to and project outwardly from the heat sink base 40. The heat sink base 40 can be formed of an appropriate material, such as copper and can be formed in a shape that is configured to receive the fin set 42. In this regard, the heat sink base 40 defines a recess or cavity 44 into which the fin set 42 can be received. The cavity 44 is open on at least two ends to permit a flow of cooling fluid to pass through the cavity 44.

[0028] In the particular example provided, the heat sink base 40 has a rectangular tubular configuration with a pair of first walls 46, which are parallel to one another, and a pair of second walls 48 that are parallel to one another and perpendicular to the first walls 46. Each of the second walls 48 is fixedly coupled to respective ends of the first walls 46. It will be appreciated that the heat sink base 40 could be formed of a tubular material having a different cross-sectional shape (e.g., triangular, round, square, oval), or that the heat sink base 40 could beformed so that one or more of the sides of the heat sink base 40 is at ieast partly “open”, for example as a channel.

[0029] The fin set 42 can define a plurality of fin members 50 and a plurality of crests 52, where each crest 52 connects one of the fin members 50 to an adjacent one of the fin members 50 to give the fin set 42 a pleated configuration. The fin set 42 can be formed of any desired material, such as a sheet of copper, aluminum or stainless steel, for example. In the particular example provided, the fin set 42 is formed of folded copper sheet. If desired, the material that forms the fin set 42 can be perforated, or can be an “expanded” sheet (i.e., a sheet that is cut and stretched to form a regular pattern of mesh-like material) or a mesh-like in its configuration.

[0030] The fin set 42 can be received in the cavity 44 in the heat sink base 40 and can be fixedly and thermally coupled to the heat sink base 40. For example, some or ail of the crests 52 can be soldered, brazed, welded, or sintered with silver- or copper-based sinter techniques to an associated interior surface of one of the first wails 46. An exterior surface of one of the first walls 46 can be fixedly and thermally coupled to the plate terminal 24, for example through soldering, brazing or sintering.

[0031] With reference to Figures 8-10, a portion of an inverter 60 for an electric motor (not shown) is illustrated. Except as described herein, the inverter 60 can be configured in a manner that is disclosed in international (PCT) Patent Application No. PCT / US2022 / 019900 filed March 11 , 2022 or U.S. Application No. 17 / 838396 filed June 13, 2022, the disclosures of which are incorporated byreference as if fully set forth in detail herein, in brief, the inverter 60 includes an inverter mount 62, a plurality of the heat-sinked power semiconductors 10, and a plurality of bus bars that include a plurality of bus bars, including a positive bus bar 64, a negative bus bar 66 and a plurality of phase bus bars 68.

[0032] The inverter mount 62 is formed of an insulating plastic material and defines a base 70, an outer circumferential wall 72, an intermediate circumferential wall 74, an inner circumferential wall 76 and a plurality of cavities 78 that are disposed radially between the outer circumferential wall 72 and the intermediate circumferential wall 74. The cavities 78 are spaced circumferentially apart from one another about the intermediate circumferential wail 74. A plurality of sets of terminal receptacles (not specifically shown) are formed through the base 70, and each set of terminal receptacles intersects a corresponding one of the cavities. Each of the heat-sinked power semiconductors 10 is received into a corresponding one of the cavities 78, with the pin terminals 22 of the power semiconductor 12 being received in the terminal receptacles such that the pin terminals 22 extend through the base 70. It will be appreciated that the pin terminals 22 can be mechanically and electrically coupled to the positive bus bar 64, the negative bus bar 66 and the phase bus bars 68 to electrically couple the power semiconductors 12 to the bus bars.

[0033] A cooling fluid can be provided to the interior of the heat sink bases40 and to the fin sets 42 in any desired manner. In the example provided, a plurality of coolant ports 80 are formed through the intermediate circumferential wall 74 and permit a cooling fluid to flow from an annular region between the innercircumferential wall 76 and the intermediate circumferential wall 74 into each of the cavities 78. in this regard, each coolant port 80 fluidly connects an associated one of the cavities 78 with the annular region between the inner circumferential wall 76 and the intermediate circumferential wall 74.

[0034] Turning to Figure 11 , another implementation of a heat-sinked power semiconductor 10’ is shown. The heat-sinked power semiconductor 10’ can include a power semiconductor 12 and heat sink 14’. The heat sink 14’ can include a fin set 42’ that defines a plurality of fin members 50 and a plurality of crests 52, where each crest 52 connects one of the fin members 50 to an adjacent one of the fin members 50 to give the fin set 42’ a pleated configuration. In one implementation, a fin set 42’ can include 22 fin members 50. The fin set 42’ can be unbounded by walls and configured to directly bond or couple with an outer surface of the power semiconductor 12. For example, the fin set 42’ could fixedly couple to the encapsulant body 26 or the plate terminal 24. In one Implementation, one or more of the crests 52 can directly bond with the plate terminal 24, such as by soldering or welding. The fin set 42’ can be formed of any desired material, such as a sheet of copper, aluminum or stainless steel, for example. In one implementation, the fin set 42' is formed of folded copper sheet.

[0035] Figure 12 depicts another implementation of the fin set 42’. The fin set 42' can define a plurality of fin members 50 and a plurality of crests 52', where each crest 52’ connects one of the fin members 50 to an adjacent one of the fin members 50 to give the fin set 42 a creased fold configuration. The creased fold can be created by mechanically reducing the thickness of a sheet of material usedto form the fin set 42’ at periodic intervals or distances coinciding with the position along the sheet where crests 52' will exist in an assembled form. The sheet of material, such as copper, aluminum, or stainless steel, can be roll formed to reduce the thickness of the sheet at the location where the crests 52’ will be formed. The crests 52’ can later be bent approximately 180 degrees at these locations. The process through which the sheet is periodically reduced in thickness can create notches 86 on a face surface 88 of a fin member 50 and on an opposing face surface 90 of an adjacent fin member 50. The notches 86 can demark the beginning and ending of the reduced thickness length of the sheet. When the sheet is bent to create the fin set 42’ and the crests 52’, the notch 86 on the face surface 88 of the fin member 50 and the notch 86 on the opposing face surface 90 of an adjacent fin member 50 can position the face surface 88 and the opposing face surface 90 closer together relative to implementations without the notches 88. Such a configuration can increase the thermal conductivity of the fin set 42’ given a reduced distance between face surfaces 89, 90, thereby increasing convection and concentrating more cooling surface near the heat-sinked power semiconductor.

[0036] Figures 13-17 depict an implementation of the heat-sinked power semiconductor 10’ received within the inverter mount 60. The heat-sinked power semiconductor 10’ can be attached with a sealing pad 82 such that the sealing pad 82 abuts a first side 84 of the cavity 78 and the heat-sinked power semiconductor 10’ abuts a second side 86 of the cavity 78 that faces the first side 84. The sealing pad 82 can be substantially square or rectangular in shape when observed from aplan view, and have a height that can be selected based on an amount of force exerted by the sealing pad 82 on the heat-sinked power semiconductor 10'. The sealing pad 82 can be formed from a compressible material capable of withstanding the temperatures of the fluid flowing over the heat-sinked power semiconductor 10’. In one implementation, the sealing pad 82 can be formed from a closed-cell foam or a compressible elastomeric material. The sealing pad 82 can be compressed so that its outer surface closely abuts the fin set 42’ and forms a fluid-tight seal between he sealing pad 82 and the fin set 42’ to prevent the flow of fluid through the cavity 78 at locations other than the fin set 42’. The outer surface of the encapsulating body 26 can closely conform to the shape of the cavity 78 receiving the heat-sinked power semiconductor 10’ so that when the heat- sinked power semiconductor 10’ is received within the cavity 78, a fluid-tight seal exists between the encapsulating body 26 and the cavity 78. The first side 84 can have a surface that is non-parallel relative to the second side 86, such that when the heat-sinked power semiconductor 10’ and the sealing pad 82 are received within the cavity 78, the sealing pad 82 can be compressed and biased into a sealing engagement with the fin set 42’ of the heat-sinked power semiconductor 10’ by the non-parallel first side 84. That is, as the heat-sinked power semiconductor 10’ and the sealing pad 82 are moved into position such that the terminals extend through the terminal receptacles, the non-parallel first side 84 presses the sealing pad 82 into compression with the fin set 42’. In one implementation, the first side 84 of the cavity 78 can be angled relative to the second side 86 by an angle somewhere between 10-20 degrees.

[0037] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.

Claims

IN THE CLAIMS:1 . A heat-sinked power semiconductor assembly, comprising: a semiconductor die; a plurality of pin terminals electrically coupled to the semiconductor die; an encapsulant body at least partially enclosing the semiconductor die and the plurality of pin terminals; and a heat sink, coupled to the assembly, comprising a fin set having a plurality of fin members configured to receive a cooling fluid.

2. The heat-sinked power semiconductor assembly recited in claim 1 , further comprising a sealing pad coupled to the fin set.

3. The heat-sinked power semiconductor assembly recited in claim 2, wherein the sealing pad is a compressible material creating a fluid-resistant seal between the sealing pad and the fin set.

4. The heat-sinked power semiconductor assembly recited in claim 2, wherein the sealing pad is configured to abut a first side of a cavity having a surface that is non-parallel to a second side of the cavity that opposes the first side of the cavity.

5. The heat-sinked power semiconductor assembly recited in claim 1 , wherein the fin set is configured to receive fluid at one end and communicate the fluid to another end of the fin set.

6. The heat-sinked power semiconductor assembly recited in claim 1 , wherein the fin set includes a plurality of crests coupling the fin members.

7. The heat-sinked power semiconductor assembly recited in claim 1 , the fin set comprising a folded planar sheet.

8. The heat-sinked power semiconductor assembly recited in claim 1 , the fin set further comprising a plurality of perforations.

9. The heat-sinked power semiconductor assembly recited in claim 1 , the fin set further comprising one or more notches at a crest of the plurality of fin members.

10. The heat-sinked power semiconductor assembly recited in claim 1 , the fin set further comprising a reduced thickness section in between a face surface of one of the plurality of fin members and an opposite one of the plurality of fin members.

11. A heat-sinked power semiconductor assembly, comprising: a semiconductor die; a plurality of pin terminals electrically coupled to the semiconductor die;an encapsulant body at least partially enclosing the semiconductor die and the plurality of pin terminals; a heat sink comprising a fin set having a plurality of fin members configured to receive a cooling fluid; and a heat sink base, having a pair of first walls and a pair of second walls, wherein the fin set is received within the pair of first walls and the pair of second walls.

12. The heat-sinked power semiconductor assembly recited in claim 11 , wherein the pair of first walls and the pair of second walls are substantially parallel to each other.

13. The heat-sinked power semiconductor assembly recited in claim 11 , wherein the fin set is configured to receive fluid at one end and communicate the fluid to another end of the fin set.

14. The heat-sinked power semiconductor assembly recited in claim 11 , wherein the fin set includes a plurality of crests coupling the fin members.

15. The heat-sinked power semiconductor assembly recited in claim 14, wherein at least some of the plurality of crests are fixedly attached to the heat sink base.

16. The heat-sinked power semiconductor assembly recited in claim 11 , the fin set comprising a folded planar sheet.

17. A heat-sinked power semiconductor assembly, comprising: a semiconductor die; a plurality of pin terminals electrically coupled to the semiconductor die; an encapsulant body at least partially enclosing the semiconductor die and the plurality of pin terminals; a heat sink, coupled to the assembly, comprising a fin set having a plurality of fin members configured to receive a cooling fluid; a sealing pad, coupled to the fin set, formed from a compressible material; and an inverter mount having a plurality of cavities shaped to receive heatsinked power semiconductors, the plurality of cavities each having a first side that is non-parallel to a second side opposite the first side, such that the first side engages a surface of the sealing pad and biases the sealing pad into engagement with the fin set.

18. The heat-sinked power semiconductor assembly recited in claim 16, wherein a fluid-resistant seal exists between the sealing pad and the fin set.

19. The heat-sinked power semiconductor assembly recited in claim 16, wherein the sealing pad is closed-cell foam.

20. The heat-sinked power semiconductor assembly recited in claim 16, wherein the first side of the cavity is angled relative to the second side of the cavity between 10 degrees and 20 degrees.

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